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Large MJ, Bashiri A, Dookie Y, McNamara J, Antognini L, Aziz S, Calcagnile L, Caricato AP, Catalano R, Chila D, Cirrone GAP, Croci T, Cuttone G, Dunand S, Fabi M, Frontini L, Grimani C, Ionica M, Kanxheri K, Liberali V, Maurizio M, Maruccio G, Mazza G, Menichelli M, Monteduro AG, Morozzi A, Moscatelli F, Pallotta S, Passeri D, Pedio M, Petringa G, Peverini F, Piccolo L, Placidi P, Quarta G, Rizzato S, Sabbatini F, Servoli L, Stabile A, Talamonti C, Thomet JE, Tosti L, Villani M, Wheadon RJ, Wyrsch N, Zema N, Petasecca M. Characterization of a flexible a-Si:H detector for in vivo dosimetry in therapeutic x-ray beams. Med Phys 2024; 51:4489-4503. [PMID: 38432192 DOI: 10.1002/mp.17013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 01/24/2024] [Accepted: 02/18/2024] [Indexed: 03/05/2024] Open
Abstract
BACKGROUND The increasing use of complex and high dose-rate treatments in radiation therapy necessitates advanced detectors to provide accurate dosimetry. Rather than relying on pre-treatment quality assurance (QA) measurements alone, many countries are now mandating the use of in vivo dosimetry, whereby a dosimeter is placed on the surface of the patient during treatment. Ideally, in vivo detectors should be flexible to conform to a patient's irregular surfaces. PURPOSE This study aims to characterize a novel hydrogenated amorphous silicon (a-Si:H) radiation detector for the dosimetry of therapeutic x-ray beams. The detectors are flexible as they are fabricated directly on a flexible polyimide (Kapton) substrate. METHODS The potential of this technology for application as a real-time flexible detector is investigated through a combined dosimetric and flexibility study. Measurements of fundamental dosimetric quantities were obtained including output factor (OF), dose rate dependence (DPP), energy dependence, percentage depth dose (PDD), and angular dependence. The response of the a-Si:H detectors investigated in this study are benchmarked directly against commercially available ionization chambers and solid-state diodes currently employed for QA practices. RESULTS The a-Si:H detectors exhibit remarkable dose linearities in the direct detection of kV and MV therapeutic x-rays, with calibrated sensitivities ranging from (0.580 ± 0.002) pC/cGy to (19.36 ± 0.10) pC/cGy as a function of detector thickness, area, and applied bias. Regarding dosimetry, the a-Si:H detectors accurately obtained OF measurements that parallel commercially available detector solutions. The PDD response closely matched the expected profile as predicted via Geant4 simulations, a PTW Farmer ionization chamber and a PTW ROOS chamber. The most significant variation in the PDD performance was 5.67%, observed at a depth of 3 mm for detectors operated unbiased. With an external bias, the discrepancy in PDD response from reference data was confined to ± 2.92% for all depths (surface to 250 mm) in water-equivalent plastic. Very little angular dependence is displayed between irradiations at angles of 0° and 180°, with the most significant variation being a 7.71% decrease in collected charge at a 110° relative angle of incidence. Energy dependence and dose per pulse dependence are also reported, with results in agreement with the literature. Most notably, the flexibility of a-Si:H detectors was quantified for sample bending up to a radius of curvature of 7.98 mm, where the recorded photosensitivity degraded by (-4.9 ± 0.6)% of the initial device response when flat. It is essential to mention that this small bending radius is unlikely during in vivo patient dosimetry. In a more realistic scenario, with a bending radius of 15-20 mm, the variation in detector response remained within ± 4%. After substantial bending, the detector's photosensitivity when returned to a flat condition was (99.1 ± 0.5)% of the original response. CONCLUSIONS This work successfully characterizes a flexible detector based on thin-film a-Si:H deposited on a Kapton substrate for applications in therapeutic x-ray dosimetry. The detectors exhibit dosimetric performances that parallel commercially available dosimeters, while also demonstrating excellent flexibility results.
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Affiliation(s)
- Matthew James Large
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, New South Wales, Australia
| | - Aishah Bashiri
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, New South Wales, Australia
- School of Physics, Najran University, Najran, Saudi Arabia
| | - Yashiv Dookie
- Shoalhaven Cancer Care Centre, Nowra, New South Wales, Australia
| | - Joanne McNamara
- Shoalhaven Cancer Care Centre, Nowra, New South Wales, Australia
| | - Luca Antognini
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Photovoltaics and Thin-Film Electronics Laboratory (PV-Lab), Neuchâtel, Switzerland
| | - Saba Aziz
- INFN Sezione di Lecce, via per Arnesano, Lecce, Italy
- Department of Mathematics and Physics "Ennio de Giorgi", University of Salento, Via per Arnesano, Lecce, Italy
| | - Lucio Calcagnile
- INFN Sezione di Lecce, via per Arnesano, Lecce, Italy
- Department of Mathematics and Physics "Ennio de Giorgi", University of Salento, Via per Arnesano, Lecce, Italy
| | - Anna Paola Caricato
- INFN Sezione di Lecce, via per Arnesano, Lecce, Italy
- Department of Mathematics and Physics "Ennio de Giorgi", University of Salento, Via per Arnesano, Lecce, Italy
| | | | - Deborah Chila
- INFN Sezione di Firenze, Florence, Italy
- Department of Experimental and Biomedical Clinical Science "Mario Serio", University of Florence, Florence, Italy
| | | | | | | | - Sylvain Dunand
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Photovoltaics and Thin-Film Electronics Laboratory (PV-Lab), Neuchâtel, Switzerland
| | - Michele Fabi
- INFN Sezione di Firenze, Florence, Italy
- DiSPeA, Università di Urbino Carlo Bo, Urbino, Italy
| | - Luca Frontini
- INFN Sezione di Milano, Via Celoria 16, Milan, Italy
| | - Catia Grimani
- INFN Sezione di Firenze, Florence, Italy
- DiSPeA, Università di Urbino Carlo Bo, Urbino, Italy
| | | | - Keida Kanxheri
- INFN Sezione di Perugia, Perugia, Italy
- Dip. di Fisica e Geologia dell'Università degli Studi di Perugia, Perugia, Italy
| | | | - Martino Maurizio
- INFN Sezione di Lecce, via per Arnesano, Lecce, Italy
- Department of Mathematics and Physics "Ennio de Giorgi", University of Salento, Via per Arnesano, Lecce, Italy
| | - Giuseppe Maruccio
- INFN Sezione di Lecce, via per Arnesano, Lecce, Italy
- Department of Mathematics and Physics "Ennio de Giorgi", University of Salento, Via per Arnesano, Lecce, Italy
| | | | | | - Anna Grazia Monteduro
- INFN Sezione di Lecce, via per Arnesano, Lecce, Italy
- Department of Mathematics and Physics "Ennio de Giorgi", University of Salento, Via per Arnesano, Lecce, Italy
| | | | | | - Stefania Pallotta
- INFN Sezione di Firenze, Florence, Italy
- Department of Experimental and Biomedical Clinical Science "Mario Serio", University of Florence, Florence, Italy
| | - Daniele Passeri
- INFN Sezione di Perugia, Perugia, Italy
- Dip. di Ingegneria dell'Università degli studi di Perugia, Perugia, Italy
| | - Maddalena Pedio
- INFN Sezione di Perugia, Perugia, Italy
- CNR-IOM, Perugia, Italy
| | | | - Francesca Peverini
- INFN Sezione di Perugia, Perugia, Italy
- Dip. di Fisica e Geologia dell'Università degli Studi di Perugia, Perugia, Italy
| | | | - Pisana Placidi
- INFN Sezione di Perugia, Perugia, Italy
- Dip. di Ingegneria dell'Università degli studi di Perugia, Perugia, Italy
| | - Gianluca Quarta
- INFN Sezione di Lecce, via per Arnesano, Lecce, Italy
- Department of Mathematics and Physics "Ennio de Giorgi", University of Salento, Via per Arnesano, Lecce, Italy
| | - Silvia Rizzato
- INFN Sezione di Lecce, via per Arnesano, Lecce, Italy
- Department of Mathematics and Physics "Ennio de Giorgi", University of Salento, Via per Arnesano, Lecce, Italy
| | - Federico Sabbatini
- INFN Sezione di Firenze, Florence, Italy
- DiSPeA, Università di Urbino Carlo Bo, Urbino, Italy
| | | | | | - Cinzia Talamonti
- INFN Sezione di Firenze, Florence, Italy
- Department of Experimental and Biomedical Clinical Science "Mario Serio", University of Florence, Florence, Italy
| | - Jonathan Emanuel Thomet
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Photovoltaics and Thin-Film Electronics Laboratory (PV-Lab), Neuchâtel, Switzerland
| | | | - Mattia Villani
- INFN Sezione di Firenze, Florence, Italy
- DiSPeA, Università di Urbino Carlo Bo, Urbino, Italy
| | | | - Nicolas Wyrsch
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Photovoltaics and Thin-Film Electronics Laboratory (PV-Lab), Neuchâtel, Switzerland
| | - Nicola Zema
- INFN Sezione di Perugia, Perugia, Italy
- CNR Istituto struttura della Materia, Rome, Italy
| | - Marco Petasecca
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, New South Wales, Australia
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A Large Area Pixelated Silicon Array Detector for Independent Transit In Vivo Dosimetry. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12020537] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A large area pixelated silicon array detector named “MP987” has been developed for in vivo dosimetry. The detector was developed to overcome the non-water equivalent response of EPID (Electronic Portal Imaging Device) dosimetry systems, due to the shortfalls of the extensive corrections required. The detector, readout system and software have all been custom designed to be operated independently from the linac with the array secured directly above the EPID, to be used in combination with the 6 MV imaging system. Dosimetry characterisation measurements of percentage depth dose (PDD), dose rate dependence, radiation damage, output factors (OF), profile measurements, linearity and uniformity were performed. Additionally, the first pre-clinical tests with this novel detector of a transit dosimetry characterization and a collapsed IMRT (intensity-modulated radiation therapy) study are presented. Both PDD and OF measurements had a percentage difference of less than 2.5% to the reference detector. A maximum change in sensitivity of 4.3 ± 0.3% was observed after 30 kGy of gamma accumulated dose. Transit dosimetry measurements through a homogeneous Solid Water phantom had a measured dose within error of the TPS calculations, for field sizes between 3 × 3 cm2 and 10 × 10 cm2. A four-fraction collapsed IMRT plan on a lung phantom had absolute dose pass fractions between the MP987 and TPS (treatment planning system) from 94.2% to 97.4%, with a 5%/5 mm criteria. The ability to accurately measure dose at a transit level, without the need for correction factors derived from extensive commissioning data collection procedures, makes the MP987 a viable alternative to the EPID for in vivo dosimetry. This MP987 is this first of its kind to be successfully developed specifically for a dual detector application.
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Alharthi T, George A, Arumugam S, Holloway L, Thwaites D, Vial P. An investigation of the IQM signal variation and error detection sensitivity for patient specific pre-treatment QA. Phys Med 2021; 86:6-18. [PMID: 34049118 DOI: 10.1016/j.ejmp.2021.05.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 04/11/2021] [Accepted: 05/03/2021] [Indexed: 11/19/2022] Open
Abstract
PURPOSE To evaluate the Integral Quality Monitor (IQM) as a clinical dosimetry device for detecting photon beam delivery errors in clinically relevant conditions. MATERIALS AND METHODS The IQM's ability to detect delivery errors introduced into clinical VMAT plans for two different treatment sites was assessed. This included measuring 103 nasopharynx VMAT plans and 78 lung SBRT VMAT plans with introduced errors in gantry angle (1-5°) and in MLC-defined field size and field shift (1-5 mm). The IQM sensitivity was compared to ArcCheck detector performance. Signal dependence on field position for on-axis and asymmetrically offset square field sizes from 1 × 1 cm2 to 30 × 30 cm2 was also investigated. RESULTS The IQM detected almost all introduced clinically-significant MLC field size errors, but not some small gantry angle errors or most MLC field shift errors. The IQM sensitivity was comparable to the ArcCheck for lung SBRT, but worse for the nasopharynx plans. Differences between IQM calculated/predicted and measured signals were within ± 2% for all on-axis square fields, but up to 60% for the smallest asymmetrically offset fields at large offsets. CONCLUSION The IQM performance was consistent and reproducible. It showed highest sensitivity to the field size errors for these plans, but did not detect some clinically-significant introduced gantry angle errors or most MLC field shift errors. The IQM calculation model is still being developed, which should improve small offset-field performance. Care is required in IQM use for plan verification or online monitoring, especially for small fields that are off-axis in the detector gradient direction.
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Affiliation(s)
- Thahabah Alharthi
- Institute of Medical Physics, School of Physics, The University of Sydney, Sydney, New South Wales, Australia; School of Medicine, Taif University, Taif, Saudi Arabia; Liverpool and Macarthur Cancer Therapy Centers, Liverpool, NSW, Australia; Ingham Institute for Applied Medical Research, Sydney, NSW, Australia.
| | - Armia George
- Liverpool and Macarthur Cancer Therapy Centers, Liverpool, NSW, Australia.
| | - Sankar Arumugam
- Liverpool and Macarthur Cancer Therapy Centers, Liverpool, NSW, Australia; South Western Sydney Clinical School, University of New South Wales, Sydney, NSW, Australia.
| | - Lois Holloway
- Institute of Medical Physics, School of Physics, The University of Sydney, Sydney, New South Wales, Australia; Liverpool and Macarthur Cancer Therapy Centers, Liverpool, NSW, Australia; Ingham Institute for Applied Medical Research, Sydney, NSW, Australia; South Western Sydney Clinical School, University of New South Wales, Sydney, NSW, Australia; Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia.
| | - David Thwaites
- Institute of Medical Physics, School of Physics, The University of Sydney, Sydney, New South Wales, Australia.
| | - Phil Vial
- Liverpool and Macarthur Cancer Therapy Centers, Liverpool, NSW, Australia; Ingham Institute for Applied Medical Research, Sydney, NSW, Australia; Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia.
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Petrucci E, Radici L, Borca VC, Ferrario S, Paolini M, Pasquino M. Delta 4 Discover transmission detector: A comprehensive characterization for in-vivo VMAT monitoring. Phys Med 2021; 85:15-23. [PMID: 33945949 DOI: 10.1016/j.ejmp.2021.04.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 04/13/2021] [Accepted: 04/18/2021] [Indexed: 11/16/2022] Open
Abstract
OBJECTIVE To investigate the dosimetric behaviour, influence on photon beam fluence and error detection capability of Delta4 Discover transmission detector. METHODS The transmission detector (TRD) was characterized on a TrueBeam linear accelerator with 6 MV beams. Linearity, reproducibility and dose rate dependence were investigated. The effect on photon beam fluence was evaluated in terms of beam profiles, percentage depth dose, transmission factor and surface dose for different open field sizes. The transmission factor of the 10x10 cm2 field was entered in the TPS's configuration and its correct use in the dose calculation was verified recalculating 17 clinical IMRT/VMAT plans. Surface dose was measured for 20 IMRT fields. The capability to detect different delivery errors was investigated evaluating dose gamma index, MLC gamma index and leaf position of 15 manually modified VMAT plans. RESULTS TRD showed a linear dependence on MU. No dose rate dependence was observed. Short-term and long-term reproducibility were within 0.1% and 0.5%. The presence of the TRD did not significantly affect PDDs and profiles. The transmission factor of the 10x10 cm2 field size was 0.985 and 0.983, for FF and FFF beams respectively. The 17 recalculated plans met our clinical gamma-index passing rate, confirming the correct use of the transmission factor by the TPS. The surface dose differences for the open fields increase for shorter SSDs and greater field size. Differences in surface dose for the IMRT beams were less than 2%. Output variation ≥2%, collimator angle variations within 0.3°, gantry angle errors of 1°, jaw tracking and leaf position errors were detected. CONCLUSIONS Delta4 Discover shows good linearity and reproducibility, is not dependent on dose rate and does not affect beam quality and dose profiles. It is also capable to detect dosimetric and geometric errors and therefore it is suitable for monitoring VMAT delivery.
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Affiliation(s)
| | - Lorenzo Radici
- Medical Physics Department, A.S.L. TO4, 10015 Ivrea, TO, Italy
| | | | | | - Marina Paolini
- Radiotherapy Department, A.S.L. TO4, 10015 Ivrea, TO, Italy
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Xu P, Geng C, Shu D, Tang X, Liu H, Tian F, Ye H. Two-dimensional dose distribution measurement based on rotational optical fiber array: A Monte Carlo simulation study. RADIAT MEAS 2021. [DOI: 10.1016/j.radmeas.2021.106556] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Ade N, du Plessis FCP. Out-of-field scattering from the Integral Quality Monitor® in megavolt photon beams. Appl Radiat Isot 2020; 168:109449. [PMID: 33317891 DOI: 10.1016/j.apradiso.2020.109449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 09/24/2020] [Indexed: 11/26/2022]
Abstract
PURPOSE To investigate out-of-field scattered doses from the Integral Quality Monitor (IQM) transmission detector in megavoltage photon beams. MATERIALS AND METHODS We measured out-of-field point doses for 20 × 20 cm2 6-15 MV photon beams using 10 × 2 cm2 Gafchromic EBT3 film strips placed across the surfaces of 5-cm thick water-equivalent RW3 slabs. The films were placed at 10 cm intervals from the central axis (CAX) of each beam, up to 1.0 m away on opposite sides of the CAX. The measurements were conducted at 80 cm and 100 cm source-to-surface distances (SSD) without the IQM, and were repeated with the IQM in the paths of the beams. Measurements were also performed at 90 cm SSD for 20 × 20 and 30 × 30 cm2 15 MV fields. Surface dose profiles were then constructed from the measurements for each beam setup with and without the IQM to examine the differences in scattered dose off-axis. The dose profile for each beam setup was normalised to dose maximum measured on the CAX. RESULTS Overall, surface dose profiles acquired with the IQM in the paths of the beams were higher than the corresponding profiles without the IQM. The out-of-field dose increased with increase in photon energy, field size, and shorter SSDs, and decreased with off-axis distance. At 80 cm SSD for the 20 × 20 cm2 field, the IQM-induced surface dose ranged from -0.6% ÷ 1.9%, -0.3% ÷ 3.0%, and 0.3% ÷ 6.8% for 6, 10, and 15 MV beams, respectively. CONCLUSION The higher surface dose profiles measured with the IQM attached to the linac compared to the profiles without the IQM indicates that the device is acting as an additional source of scattered radiation.
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Affiliation(s)
- Nicholas Ade
- Medical Physics Department, University of the Free State, Bloemfontein, 9300, South Africa.
| | - F C P du Plessis
- Medical Physics Department, University of the Free State, Bloemfontein, 9300, South Africa
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Nguyen THT, Yokoyama H, Kojima H, Isomura N, Takemura A, Ueda S, Noto K. Effect of an integral quality monitor on 4-, 6-, 10-MV, and 6-MV flattening filter-free photon beams. J Appl Clin Med Phys 2020; 22:76-91. [PMID: 33270985 PMCID: PMC7856493 DOI: 10.1002/acm2.13106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 10/29/2020] [Accepted: 11/02/2020] [Indexed: 12/04/2022] Open
Abstract
Purpose To investigate the effect of an integral quality monitor (IQM; iRT Systems GmbH, Koblenz, Germany) on 4, 6, 10, and 6‐MV flattening filter‐free (FFF) photon beams. Methods We assessed surface dose, PDD20,10, TPR20,10, PDD curves, inline and crossline profiles, transmission factor, and output factor with and without the IQM. PDD, transmission factor, and output factor were measured for square fields of 3, 5, 10, 15, 20, 25, and 30 cm and profiles were performed for square fields of 3, 5, 10, 20, and 30 cm at 5‐, 10‐, and 30‐cm depth. Results The differences in surface dose of all energies for square fields of 3, 5, 10, 15, 20, and 25 cm were within 3.7% whereas for a square field of 30 cm, they were 4.6%, 6.8%, 6.7%, and 8.7% for 4‐MV, 6‐MV, 6‐MV‐FFF, and 10‐MV, respectively. Differences in PDD20,10, TPR20,10, PDD, profiles, and output factors were within ±1%. Local and global gamma values (2%/2 mm) were below 1 for PDD beyond dmax and inline/crossline profiles in the central beam region, respectively. The gamma passing rates (10% threshold) for PDD curves and profiles were above 95% at 2%/2 mm. The transmission factors for 4‐MV, 6‐MV, 6‐MV‐FFF, and 10‐MV for field sizes from 3 × 3 to 30 × 30 cm2 were 0.926–0.933, 0.937–0.941, 0.937–0.939, and 0.949–0.953, respectively. Conclusions The influence of the IQM on the beam quality (in particular 4‐MV X‐ray has not verified before) was tested and introduced a slight beam perturbation at the surface and build‐up region and the edge of the crossline/inline profiles. To use IQM in pre‐ and intra‐treatment quality assurance, a tray factor should be put into treatment planning systems for the dose calculation for the 4‐, 6‐, 10‐, and 6‐MV flattening filter‐free photon beams to compensate the beam attenuation of the IQM detector.
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Affiliation(s)
- Trang Hong Thi Nguyen
- Division of Health Sciences, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
| | - Haruna Yokoyama
- Department of Radiological Technology, Kanazawa University Hospital, Kanazawa, Japan
| | - Hironori Kojima
- Department of Radiological Technology, Kanazawa University Hospital, Kanazawa, Japan
| | - Naoki Isomura
- Department of Radiological Technology, Kanazawa University Hospital, Kanazawa, Japan
| | - Akihiro Takemura
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Shinichi Ueda
- Department of Radiological Technology, Kanazawa University Hospital, Kanazawa, Japan
| | - Kimiya Noto
- Department of Radiological Technology, Kanazawa University Hospital, Kanazawa, Japan
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Rosenfeld AB, Biasi G, Petasecca M, Lerch MLF, Villani G, Feygelman V. Semiconductor dosimetry in modern external-beam radiation therapy. Phys Med Biol 2020; 65:16TR01. [PMID: 32604077 DOI: 10.1088/1361-6560/aba163] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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C M, F C P DP. X-Ray Beam Segment Size and Entrance Location Effects on the Integral Quality Monitor (IQM®) Signal and Usefulness in Predicting Complex Segment Output Signals. J Biomed Phys Eng 2020; 10:395-410. [PMID: 32802788 PMCID: PMC7416101 DOI: 10.31661/jbpe.v0i0.1162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 06/12/2019] [Indexed: 11/16/2022]
Abstract
Background: The Integral Quality Monitor (IQM®) is an independent online dosimetry device attached to the treatment machine to monitor the accuracy of radiation delivery. Objective: This study investigates the influence of beam segment size and displacement as projected onto the IQM chamber on the signals and determine how individual signals can be added to get a combined segment signal made up of smaller segments. Material and Methods: This is an experimental original research type of study. IQM response maps were generated by irradiating the IQM sensitive area with small elementary segments and measuring their corresponding signals per monitor unit (MU). The output signal/MU was measured for regular and irregular fields and compared with the predicted signal/MU obtained from decomposing the open segment into a set of smaller regular segments and summing their signals from their respective response maps. The dependence of signals on segment size, shape, location and combination was investigated. Results: Predicted signals were calculated within 95-98 % accuracy for regular fields and 90-98% for irregular fields. More uniform fluence contain distribution for larger segments was observed. Response maps were consistent with the geometrical symmetry in the chamber’s wedge shape and the symmetry in the linac fluence. Conclusion: The field decomposition method allows the pre-calculation of known segment output signals per MU within 2% error, although the accuracy drops significantly for smaller, irregular fields. A method of correcting predicted signals in smaller segments needs to be laid down to get a better match with measured signals.
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Affiliation(s)
- Mahuvava C
- PhD, Department of Medical Physics, Faculty of Health Sciences, University of the Free State, P.O. Box 339, Bloemfontein, 9300 South Africa
| | - Du Plessis F C P
- PhD, Department of Medical Physics, Faculty of Health Sciences, University of the Free State, P.O. Box 339, Bloemfontein, 9300 South Africa
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Esposito M, Villaggi E, Bresciani S, Cilla S, Falco MD, Garibaldi C, Russo S, Talamonti C, Stasi M, Mancosu P. Estimating dose delivery accuracy in stereotactic body radiation therapy: A review of in-vivo measurement methods. Radiother Oncol 2020; 149:158-167. [PMID: 32416282 DOI: 10.1016/j.radonc.2020.05.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 05/08/2020] [Accepted: 05/10/2020] [Indexed: 12/25/2022]
Abstract
Stereotactic body radiation therapy (SBRT) has been recognized as a standard treatment option for many anatomical sites. Sophisticated radiation therapy techniques have been developed for carrying out these treatments and new quality assurance (QA) programs are therefore required to guarantee high geometrical and dosimetric accuracy. This paper focuses on recent advances on in-vivo measurements methods (IVM) for SBRT treatment. More specifically, all of the online QA methods for estimating the effective dose delivered to patients were compared. Determining the optimal IVM for performing SBRT treatments would reduce the risk of errors that could jeopardize treatment outcome. A total of 89 papers were included. The papers were subdivided into the following topics: point dosimeters (PD), transmission detectors (TD), log file analysis (LFA), electronic portal imaging device dosimetry (EPID), dose accumulation methods (DAM). The detectability capability of the main IVM detectors/devices were evaluated. All of the systems have some limitations: PD has no spatial data, EPID has limited sensitivity towards set-up errors and intra-fraction motion in some anatomical sites, TD is insensitive towards patient related errors, LFA is not an independent measure, DAMs are not always based on measures. In order to minimize errors in SBRT dose delivery, we recommend using synergic combinations of two or more of the systems described in our review: on-line tumor position and patient information should be combined with MLC position and linac output detection accuracy. In this way the effects of SBRT dose delivery errors will be reduced.
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Affiliation(s)
- Marco Esposito
- S.C. Fisica Sanitaria Firenze-Empoli, Azienda Sanitaria USL Toscana Centro, Italy.
| | | | - Sara Bresciani
- Medical Physics, Candiolo Cancer Institute - FPO IRCCS, Turin, Italy
| | - Savino Cilla
- Medical Physics Unit, Gemelli Molise Hospital, Campobasso, Italy
| | - Maria Daniela Falco
- Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Cristina Garibaldi
- Radiation Research Unit, European Institute of Oncology IRCCS, Milan, Italy
| | - Serenella Russo
- S.C. Fisica Sanitaria Firenze-Empoli, Azienda Sanitaria USL Toscana Centro, Italy
| | - Cinzia Talamonti
- University of Florence, Dept Biomedical Experimental and Clinical Science, "Mario Serio", Medical Physics Unit, AOU Careggi, Florence, Italy
| | - Michele Stasi
- Medical Physics, Candiolo Cancer Institute - FPO IRCCS, Turin, Italy
| | - Pietro Mancosu
- Medical Physics Unit of Radiotherapy Dept., Humanitas Clinical and Research Hospital - IRCCS, Rozzano, Italy
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12
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Albert S, Brivio D, Aldelaijan S, Sajo E, Hesser J, Zygmanski P. Towards customizable thin-panel low-Z detector arrays: electrode design for increased spatial resolution ion chamber arrays. Phys Med Biol 2020; 65:08NT02. [PMID: 32187595 DOI: 10.1088/1361-6560/ab8109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The purpose of the present development is to employ 3D printing to prototype an ion chamber array with a scalable design potentially allowing increased spatial resolution and a larger active area. An additional goal is to design and fabricate a custom size thin-panel detector array with low-Z components. As a proof of principle demonstration, a medium size detector array with 30 × 30 air-vented ion chambers was 3D-printed using PLA as frame for the electrodes. The active-area is 122 mm × 120 mm with 4 × 4 mm2 spatial resolution. External electrodes are cylindrical and made from conductive PLA. Internal electrodes are made from microwire. The array is symmetric with respect to the central plane and its thickness is 10 mm including build-up/-down plates of 2.5 mm thickness. Data acquisition is realized by biasing only selected chamber rows and reading only 30 chambers at a time. To test the device for potential clinical applications, 1D dose profiles and 2D dose maps with various square and irregular fields were measured. The overall agreement with the reference doses (film and treatment planning system) was satisfactory, but the measured dose differs in the penumbra region and in the field size dependence. Both of these features are related to the thin walls between neighboring ion chambers and different lateral phantom scatter in the detector panel vs homogeneous material. We demonstrated feasibility of radiation detector arrays with minimal number of readout channels and low-cost electronics. The acquisition scheme based on selected row or column 'activation' by bias voltage is not practical for 2D dosimetry but it allows for rapid turn-around when testing of custom arrays with the aid of multiple 1D dose profiles. Future progress in this area includes overcoming the limitations due high chamber packing ratio, which leads to the lateral scattering effects.
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Affiliation(s)
- Steffen Albert
- Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States of America. Heidelberg University, Heidelberg, Germany. University of Massachusetts Lowell, MA, United States of America
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13
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Mahuvava C, Du Plessis FCP. External beam patient dose verification based on the integral quality monitor (IQM ®) output signals. Biomed Phys Eng Express 2020; 6:035014. [PMID: 33438659 DOI: 10.1088/2057-1976/ab5f55] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND The Integral Quality Monitor (IQM®) can essentially measure the integral fluence through a segment and provide real-time information about the accuracy of radiation delivery based on comparisons of measured segment signals and pre-calculated reference values. However, the present IQM chamber cannot calculate the dose in the patient. AIM This study aims to make use of IQM field output signals to calculate the number of monitor units (MUs) delivered through an arbitrary treatment field in order to convert Monte Carlo (MC)-generated dose distributions in a patient model into absolute dose. METHODS XiO and Monaco treatment planning systems (TPSs) were used to define treatment beam portals for cervix and esophagus conformal radiotherapy as well as prostate intensity-modulated radiotherapy for the translation of patient and beam setup information from DICOM to DOSXYZnrc. The planned beams were simulated in a patient model built from actual patient CT images and each simulated integral field/segment was weighted with its MUs before summation to get the total dose in the plan. The segment beam weights (MUs) were calculated as the ratio of the open-field IQM measured signal and the calculated signal per MU extracted from chamber sensitivity maps. These are the actual MUs delivered not just MUs set. The beam weighting method was evaluated by comparing weighted MC doses with original planned doses using profile and isodose comparisons, dose difference maps, γ analysis and dose-volume histogram (DVH) data. RESULTS γ pass rates of up to 98% were found, except for the esophagus plan where the γ pass rate was below 45%. DVH comparisons showed good agreement for most organs, with the largest differences observed in low-density lung. However, these discrepancies can result from differences in dose calculation algorithms or differences in MUs used for dose weighting planned by the TPS and MUs calculated using IQM field output signals. To test this, a 4-field box DOSXYZnrc MC simulation weighted with planned (XiO) MUs was compared with the same simulation weighted with IQM-based MUs. Dose differences of up to 5% were found on the isocentre slice. For XiO versus MC, up to 7% dose differences were found, indicating additional error due to limitations of XiO's superposition algorithm. Dose differences between MC Monaco and MC EGSnrc were less than 3%. CONCLUSIONS The most valuable comparison was MC versus MC as it eliminated algorithm discrepancies and evaluated dose differences precisely according to beam weighting. For XiO TPS, care must be taken as dose differences may also arise due to limitations in XiO's planning software, not merely due to differences in MUs. Overall, the IQM was successfully used to compute beam dose weights to accurately reconstruct the patient dose using unweighted MC beams. Our technique can be used for pre-treatment QA provided each segment output is known and an accurate linac source model is available.
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Affiliation(s)
- Courage Mahuvava
- Medical Physics Department, Faculty of Health Sciences, University of the Free State, P O Box 339, Bloemfontein 9300, South Africa
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14
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Alnaghy SJ, Causer T, Roberts N, Oborn B, Jelen U, Dong B, Gargett M, Begg J, Liney G, Petasecca M, Rosenfeld AB, Holloway L, Metcalfe P. High resolution silicon array detector implementation in an inline MRI-linac. Med Phys 2020; 47:1920-1929. [PMID: 31917865 DOI: 10.1002/mp.14016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 01/06/2020] [Accepted: 01/07/2020] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Dynamic dosimaging is a concept whereby a detector in motion is tracked with magnetic resonance imaging (MRI) to validate the amount and position of dose in a radiation therapy treatment on an MRI-linac. This work takes steps toward the realization of dynamic dosimaging with the novel high resolution silicon array detector: MagicPlate-512 (M512). The performance of the M512 was assessed in a 1.0 T inline MRI-linac, without simultaneous imaging and then during an imaging sequence, both during dosimetry. MR images were acquired to determine the effect of the detector and its components on image quality. METHODS Beam profiles were measured using the M512 on the Australian MRI-Linac and a comparison made with Gafchromic EBT3 film to investigate any intrinsic magnetic field effects in the silicon. The M512 has 512 sensitive volumes, each 0.5 × 0.5 × 0.037 mm3 in dimension, organized in a two-dimensional array. Small field sizes up to 4.2 × 3.8 cm2 were investigated in both solid water and then solid lung phantoms. Beam profiles taken at 1.0 T were compared to 0 T conditions, and also to profiles taken during a gradient echo (GRE) imaging sequence. Differences in 80%-20% penumbral width and full width at half maximum (FWHM) were investigated. Localizer MR images were acquired of the detector adjacent to a water phantom. RESULTS Good agreement was observed between the M512 and film, with average differences in penumbral width and FWHM of <1 mm in the absence of the imaging sequence. Concurrent imaging widened the penumbra by up to 1.2 mm due to RF noise affecting the detector; film profiles were unchanged. Magnetic resonance images were affected by noise, in particular, due to the large amount of aluminum present, as well as from the USB cable, which acted as an antenna. Unfortunately, due to these issues, suitable dynamic dose imaging was not achieved with the current M512/phantom configuration and the MRI-linac. However, progress was made toward achieving this goal for future work. CONCLUSIONS The M512 silicon array detector successfully measured high-resolution beam profiles in agreement with Gafchromic film to within an average of <1 mm on the first MRI-linac in Australia. More effective noise reduction will be required for the achievement of dynamic dosimaging in the future.
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Affiliation(s)
- Sarah J Alnaghy
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, 2522, Australia.,Ingham Institute for Applied Medical Research, Liverpool, NSW, 2170, Australia
| | - Trent Causer
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, 2522, Australia.,Illawarra Cancer Care Centre, Wollongong Hospital, Wollongong, NSW, 2500, Australia
| | - Natalia Roberts
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, 2522, Australia.,Ingham Institute for Applied Medical Research, Liverpool, NSW, 2170, Australia
| | - Brad Oborn
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, 2522, Australia.,Illawarra Cancer Care Centre, Wollongong Hospital, Wollongong, NSW, 2500, Australia
| | - Urszula Jelen
- Ingham Institute for Applied Medical Research, Liverpool, NSW, 2170, Australia.,Department of Medical Physics, Liverpool and Macarthur Cancer Therapy Centre, Liverpool, NSW, 2170, Australia
| | - Bin Dong
- Ingham Institute for Applied Medical Research, Liverpool, NSW, 2170, Australia.,Department of Medical Physics, Liverpool and Macarthur Cancer Therapy Centre, Liverpool, NSW, 2170, Australia
| | - Maegan Gargett
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, 2522, Australia.,Northern Sydney Cancer Centre, Royal North Shore Hospital, St. Leonards, NSW, 2065, Australia
| | - Jarrad Begg
- Ingham Institute for Applied Medical Research, Liverpool, NSW, 2170, Australia.,Department of Medical Physics, Liverpool and Macarthur Cancer Therapy Centre, Liverpool, NSW, 2170, Australia.,South Western Sydney Clinical School, University of New South Wales, Liverpool, NSW, 2170, Australia
| | - Gary Liney
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, 2522, Australia.,Ingham Institute for Applied Medical Research, Liverpool, NSW, 2170, Australia.,Department of Medical Physics, Liverpool and Macarthur Cancer Therapy Centre, Liverpool, NSW, 2170, Australia.,South Western Sydney Clinical School, University of New South Wales, Liverpool, NSW, 2170, Australia
| | - Marco Petasecca
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Anatoly B Rosenfeld
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Lois Holloway
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, 2522, Australia.,Ingham Institute for Applied Medical Research, Liverpool, NSW, 2170, Australia.,Illawarra Cancer Care Centre, Wollongong Hospital, Wollongong, NSW, 2500, Australia.,Department of Medical Physics, Liverpool and Macarthur Cancer Therapy Centre, Liverpool, NSW, 2170, Australia.,South Western Sydney Clinical School, University of New South Wales, Liverpool, NSW, 2170, Australia.,Institute of Medical Physics, University of Sydney, Camperdown, NSW, 2505, Australia
| | - Peter Metcalfe
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, 2522, Australia.,Ingham Institute for Applied Medical Research, Liverpool, NSW, 2170, Australia
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15
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Utitsarn K, Biasi G, Stansook N, Alrowaili ZA, Petasecca M, Carolan M, Perevertaylo VL, Tomé WA, Kron T, Lerch MLF, Rosenfeld AB. Two-dimensional solid-state array detectors: A technique for in vivo dose verification in a variable effective area. J Appl Clin Med Phys 2019; 20:88-94. [PMID: 31609090 PMCID: PMC6839376 DOI: 10.1002/acm2.12744] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 07/25/2019] [Accepted: 09/16/2019] [Indexed: 11/24/2022] Open
Abstract
Purpose We introduce a technique that employs a 2D detector in transmission mode (TM) to verify dose maps at a depth of dmax in Solid Water. TM measurements, when taken at a different surface‐to‐detector distance (SDD), allow for the area at dmax (in which the dose map is calculated) to be adjusted. Methods We considered the detector prototype “MP512” (an array of 512 diode‐sensitive volumes, 2 mm spatial resolution). Measurements in transmission mode were taken at SDDs in the range from 0.3 to 24 cm. Dose mode (DM) measurements were made at dmax in Solid Water. We considered radiation fields in the range from 2 × 2 cm2 to 10 × 10 cm2, produced by 6 MV flattened photon beams; we derived a relationship between DM and TM measurements as a function of SDD and field size. The relationship was used to calculate, from TM measurements at 4 and 24 cm SDD, dose maps at dmax in fields of 1 × 1 cm2 and 4 × 4 cm2, and in IMRT fields. Calculations were cross‐checked (gamma analysis) with the treatment planning system and with measurements (MP512, films, ionization chamber). Results In the square fields, calculations agreed with measurements to within ±2.36%. In the IMRT fields, using acceptance criteria of 3%/3 mm, 2%/2 mm, 1%/1 mm, calculations had respective gamma passing rates greater than 96.89%, 90.50%, 62.20% (for a 4 cm SSD); and greater than 97.22%, 93.80%, 59.00% (for a 24 cm SSD). Lower rates (1%/1 mm criterion) can be explained by submillimeter misalignments, dose averaging in calculations, noise artifacts in film dosimetry. Conclusions It is possible to perform TM measurements at the SSD which produces the best fit between the area at dmax in which the dose map is calculated and the size of the monitored target.
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Affiliation(s)
- Kananan Utitsarn
- Centre for Medical Radiation Physics (CMRP)University of WollongongWollongongNSWAustralia
- Department of Medical ServicesLopburi Cancer HospitalLopburiThailand
| | - Giordano Biasi
- Centre for Medical Radiation Physics (CMRP)University of WollongongWollongongNSWAustralia
| | - Nauljun Stansook
- Centre for Medical Radiation Physics (CMRP)University of WollongongWollongongNSWAustralia
- Department of RadiologyFaculty of MedicineMahidol UniversityBangkokThailand
| | - Ziyad A. Alrowaili
- Centre for Medical Radiation Physics (CMRP)University of WollongongWollongongNSWAustralia
- Physics DepartmentCollege of ScienceJouf UniversitySakakaSaudi Arabia
| | - Marco Petasecca
- Centre for Medical Radiation Physics (CMRP)University of WollongongWollongongNSWAustralia
| | - Martin Carolan
- Illawarra Cancer Care Centre (ICCC)Wollongong HospitalWollongongNSWAustralia
| | | | - Wolfgang A. Tomé
- Department of Radiation OncologyAlbert Einstein College of MedicineNew York CityNYUSA
| | - Tomas Kron
- Centre for Medical Radiation Physics (CMRP)University of WollongongWollongongNSWAustralia
- Department of Physical SciencesPeter MacCallum Cancer CentreMelbourneVic.Australia
- Sir Peter MacCallum Cancer InstituteUniversity of MelbourneMelbourneVic.Australia
| | - Michael L. F. Lerch
- Centre for Medical Radiation Physics (CMRP)University of WollongongWollongongNSWAustralia
| | - Anatoly B. Rosenfeld
- Centre for Medical Radiation Physics (CMRP)University of WollongongWollongongNSWAustralia
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16
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Mahuvava C, Du Plessis FCP. Integral quality monitor (IQM
®
) signal correction factors for small fields to predict larger irregular segment output signals. Med Phys 2019; 46:5848-5860. [DOI: 10.1002/mp.13831] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 08/07/2019] [Accepted: 09/09/2019] [Indexed: 11/09/2022] Open
Affiliation(s)
- Courage Mahuvava
- Medical Physics Department Faculty of Health Sciences University of the Free State P.O. Box 339 Bloemfontein 9300South Africa
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17
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Nascimento L, Crijns W, Goveia G, Mirotta Z, Souza L, Vanhavere F, Saldarriaga Vargas C, De Saint-Hubert M. 2D reader for dose mapping in radiotherapy using radiophotoluminescent films. RADIAT MEAS 2019. [DOI: 10.1016/j.radmeas.2019.106202] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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18
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Oderinde OM, du Plessis F. Sensitivity of the IQM and MatriXX detectors in megavolt photon beams. Rep Pract Oncol Radiother 2019; 24:462-471. [DOI: 10.1016/j.rpor.2019.07.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 06/12/2019] [Accepted: 07/11/2019] [Indexed: 10/26/2022] Open
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19
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Sarkar V, Paxton A, Kunz J, Szegedi M, Nelson G, Rassiah‐Szegedi P, Zhao H, Huang YJ, Su F, Salter BJ. A systematic evaluation of the error detection abilities of a new diode transmission detector. J Appl Clin Med Phys 2019; 20:122-132. [PMID: 31385436 PMCID: PMC6753730 DOI: 10.1002/acm2.12691] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 06/19/2019] [Accepted: 07/20/2019] [Indexed: 02/02/2023] Open
Abstract
Transmission detectors meant to measure every beam delivered on a linear accelerator are now becoming available for monitoring the quality of the dose distribution delivered to the patient daily. The purpose of this work is to present results from a systematic evaluation of the error detection capabilities of one such detector, the Delta4 Discover. Existing patient treatment plans were modified through in‐house‐developed software to mimic various delivery errors that have been observed in the past. Errors included shifts in multileaf collimator leaf positions, changing the beam energy from what was planned, and a simulation of what would happen if the secondary collimator jaws did not track with the leaves as they moved. The study was done for simple 3D plans, static gantry intensity modulated radiation therapy plans as well as dynamic arc and volumetric modulated arc therapy (VMAT) plans. Baseline plans were delivered with both the Discover device and the Delta4 Phantom+ to establish baseline gamma pass rates. Modified plans were then delivered using the Discover only and the predicted change in gamma pass rate, as well as the detected leaf positions were evaluated. Leaf deviations as small as 0.5 mm for a static three‐dimensional field were detected, with this detection limit growing to 1 mm with more complex delivery modalities such as VMAT. The gamma pass rates dropped noticeably once the intentional leaf error introduced was greater than the distance‐to‐agreement criterion. The unit also demonstrated the desired drop in gamma pass rates of at least 20% when jaw tracking was intentionally disabled and when an incorrect energy was used for the delivery. With its ability to find errors intentionally introduced into delivered plans, the Discover shows promise of being a valuable, independent error detection tool that should serve to detect delivery errors that can occur during radiotherapy treatment.
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Affiliation(s)
| | | | | | | | | | | | - Hui Zhao
- University of UtahSalt Lake CityUTUSA
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20
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Alnaghy SJ, Causer T, Gargett M, Roberts N, Petasecca M, Oborn BM, Rosenfeld AB, Holloway L, Metcalfe P. A feasibility study for high-resolution silicon array detector performance in the magnetic field of a permanent magnet system. Med Phys 2019; 46:4224-4232. [PMID: 31246282 DOI: 10.1002/mp.13686] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 05/27/2019] [Accepted: 06/17/2019] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Magnetic field effects on dose distribution and detector functionality must be well understood. The detector utilized to investigate these magnetic field effects was the DUO silicon array detector; the performance of this high spatial resolution detector was assessed under these conditions. The results were compared to Gafchromic EBT3 film to highlight any intrinsic magnetic field effects in the silicon. The results were also compared to previously published MagicPlate-512 (M512) data. The DUO has an improved spatial resolution (200 µm) over the M512 (2 mm). METHODS A permanent magnet named Magnetic Apparatus for RaDiation Oncology Studies (MARDOS) paired with a standard linear accelerator (linac) enables either transverse (1.2 T) or inline (0.95 T) orientations of the magnetic field with respect to the radiation beam. A 6 MV Varian 2100C Linac provided the radiation component for the measurements. The DUO detector has 505 sensitive volumes (each volume measuring 800 × 40 × 100 µm3 ) organized in two orthogonal, linear arrays. The DUO was embedded in a solid water phantom in the first set-up and then a solid lung phantom in the second set-up and placed between the magnet cones. Beam profiles were compared under the magnetic field conditions and 0 T. Small field sizes from 0.8 × 0.8 cm2 up to 2.3 × 2.3 cm2 were investigated. The size of the air gap above the sensitive volumes of the DUO was investigated in the transverse orientation to assess the anticipated magnetic field effects. Full width at half maximum (FWHM), 80-20% penumbral widths and maximum dose differences between detectors and between the presence/absence of a magnetic field were investigated. Symmetry was also assessed for investigation of profile skewness under the transverse field. RESULTS The penumbral widths measured by the DUO detector demonstrated good agreement with film and the M512 to within an average of 0.5 mm (within uncertainty: ±1 mm). The static inline magnetic field had minimal effect on the profiles in solid water. As expected, the lower density of solid lung meant that this material was more susceptible to demonstrating magnetic field effects in the dose deposited. The greatest penumbral narrowing due to the inline field (0.7 mm) occurred in lung. Central axis dose increase was greatest in lung (maximum: 9%). The transverse field widened penumbra, most notably in the solid lung phantom, by a maximum of 2.3 mm. The largest asymmetry due to the transverse field (4.6%) was also in solid lung. When the air gap above the DUO was filled with bolus, the dose maximum measured by the DUO was within 1.4% of film. CONCLUSIONS The DUO detector has been shown to be successful in accurately describing the dose changes for small field sizes to within a 200-µm resolution in an environment resembling that of an MRI-linac. The DUO measurements were in agreement with both film and the M512 measurements, and therefore the DUO was found to be an appropriate alternative to the M512, with improvement in terms of its higher spatial resolution. MARDOS provided a suitable environment for these preliminary tests before progressing to the MRI-linac.
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Affiliation(s)
- Sarah J Alnaghy
- Centre for Medical Radiation Physics, University of Wollongong, New South Wales (NSW), Wollongong, 2522, Australia.,Ingham Institute for Applied Medical Research, Liverpool, NSW, 2170, Australia
| | - Trent Causer
- Centre for Medical Radiation Physics, University of Wollongong, New South Wales (NSW), Wollongong, 2522, Australia.,Ingham Institute for Applied Medical Research, Liverpool, NSW, 2170, Australia.,Illawarra Cancer Care Centre, Wollongong Hospital, Wollongong, NSW, 2500, Australia
| | - Maegan Gargett
- Centre for Medical Radiation Physics, University of Wollongong, New South Wales (NSW), Wollongong, 2522, Australia.,Northern Sydney Cancer Centre, Royal North Shore Hospital, St. Leonards, NSW, 2065, Australia
| | - Natalia Roberts
- Centre for Medical Radiation Physics, University of Wollongong, New South Wales (NSW), Wollongong, 2522, Australia.,Ingham Institute for Applied Medical Research, Liverpool, NSW, 2170, Australia
| | - Marco Petasecca
- Centre for Medical Radiation Physics, University of Wollongong, New South Wales (NSW), Wollongong, 2522, Australia
| | - Brad M Oborn
- Centre for Medical Radiation Physics, University of Wollongong, New South Wales (NSW), Wollongong, 2522, Australia.,Illawarra Cancer Care Centre, Wollongong Hospital, Wollongong, NSW, 2500, Australia
| | - Anatoly B Rosenfeld
- Centre for Medical Radiation Physics, University of Wollongong, New South Wales (NSW), Wollongong, 2522, Australia
| | - Lois Holloway
- Centre for Medical Radiation Physics, University of Wollongong, New South Wales (NSW), Wollongong, 2522, Australia.,Ingham Institute for Applied Medical Research, Liverpool, NSW, 2170, Australia.,Illawarra Cancer Care Centre, Wollongong Hospital, Wollongong, NSW, 2500, Australia.,Department of Medical Physics, Liverpool and Macarthur Cancer Therapy Centre, Liverpool, NSW, 2170, Australia.,South Western Sydney Clinical School, University of New South Wales, Liverpool, NSW, 2170, Australia.,Institute of Medical Physics, University of Sydney, Camperdown, NSW, 2505, Australia.,Central Clinical School, University of Sydney, Camperdown, NSW, 2505, Australia
| | - Peter Metcalfe
- Centre for Medical Radiation Physics, University of Wollongong, New South Wales (NSW), Wollongong, 2522, Australia.,Ingham Institute for Applied Medical Research, Liverpool, NSW, 2170, Australia
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21
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Oderinde OM, Du Plessis F. Sensitivity evaluation of two commercial quality assurance systems to organ-dose variations of patient-specific VMAT plans. JOURNAL OF RADIATION RESEARCH AND APPLIED SCIENCES 2019. [DOI: 10.1080/16878507.2019.1618080] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Oluwaseyi M. Oderinde
- Department of Medical Physics, University of the Free State, Bloemfontein Republic of South Africa
| | - Freek Du Plessis
- Department of Medical Physics, University of the Free State, Bloemfontein Republic of South Africa
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22
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Razinskas G, Wegener S, Greber J, Sauer OA. Sensitivity of the IQM transmission detector to errors of VMAT plans. Med Phys 2018; 45:5622-5630. [DOI: 10.1002/mp.13228] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 09/28/2018] [Accepted: 09/28/2018] [Indexed: 11/09/2022] Open
Affiliation(s)
- Gary Razinskas
- Radiation Oncology University of Wuerzburg Josef‐Schneider‐Str. 11 97080 Wuerzburg Germany
| | - Sonja Wegener
- Radiation Oncology University of Wuerzburg Josef‐Schneider‐Str. 11 97080 Wuerzburg Germany
| | - Johannes Greber
- Radiation Oncology University of Wuerzburg Josef‐Schneider‐Str. 11 97080 Wuerzburg Germany
| | - Otto A. Sauer
- Radiation Oncology University of Wuerzburg Josef‐Schneider‐Str. 11 97080 Wuerzburg Germany
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23
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Biasi G, Petasecca M, Guatelli S, Martin EA, Grogan G, Hug B, Lane J, Perevertaylo V, Kron T, Rosenfeld AB. CyberKnife ® fixed cone and Iris™ defined small radiation fields: Assessment with a high-resolution solid-state detector array. J Appl Clin Med Phys 2018; 19:547-557. [PMID: 29998618 PMCID: PMC6123130 DOI: 10.1002/acm2.12414] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 05/13/2018] [Accepted: 06/18/2018] [Indexed: 11/18/2022] Open
Abstract
Purpose The challenges of accurate dosimetry for stereotactic radiotherapy (SRT) with small unflattened radiation fields have been widely reported in the literature. In this case, suitable dosimeters would have to offer a submillimeter spatial resolution. The CyberKnife® (Accuray Inc., Sunnyvale, CA, USA) is an SRT‐dedicated linear accelerator (linac), which can deliver treatments with submillimeter positional accuracy using circular fields. Beams are delivered with the desired field size using fixed cones, the InCise™ multileaf collimator or a dynamic variable‐aperture Iris™ collimator. The latter, allowing for field sizes to be varied during treatment delivery, has the potential to decrease treatment time, but its reproducibility in terms of output factors (OFs) and dose profiles (DPs) needs to be verified. Methods A 2D monolithic silicon array detector, the “Octa”, was evaluated for dosimetric quality assurance (QA) for a CyberKnife system. OFs, DPs, percentage depth‐dose (PDD) and tissue maximum ratio (TMR) were investigated, and results were benchmarked against the PTW SRS diode. Cross‐plane, in‐plane and 2 diagonal dose profiles were measured simultaneously with high spatial resolution (0.3 mm). Monte Carlo (MC) simulations with a GEANT4 (GEometry ANd Tracking 4) tool‐kit were added to the study to support the experimental characterization of the detector response. Results For fixed cones and the Iris, for all field sizes investigated in the range between 5 and 60 mm diameter, OFs, PDDs, TMRs, and DPs in terms of FWHM measured by the Octa were accurate within 3% when benchmarked against the SRS diode and MC calculations. Conclusions The Octa was shown to be an accurate dosimeter for measurements with a 6 MV FFF beam delivered with a CyberKnife system. The detector enabled real‐time dosimetric verification for the variable aperture Iris collimator, yielding OFs and DPs consistent with those obtained with alternative methods.
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Affiliation(s)
- Giordano Biasi
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, 2522 NSW, Australia
| | - Marco Petasecca
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, 2522 NSW, Australia
| | - Susanna Guatelli
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, 2522 NSW, Australia
| | - Ebert A Martin
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, 2522 NSW, Australia.,Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, Australia.,School of Physics and Astrophysics, University of Western Australia, Crawley, WA, Australia
| | - Garry Grogan
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, Australia
| | - Benjamin Hug
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, Australia.,School of Physics and Astrophysics, University of Western Australia, Crawley, WA, Australia
| | - Jonathan Lane
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, Australia
| | | | - Tomas Kron
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, 2522 NSW, Australia.,Peter MacCallum Cancer Centre, Melbourne, VIC, Australia.,Sir Peter MacCallum Cancer Institute, University of Melbourne, Melbourne, VIC, Australia
| | - Anatoly B Rosenfeld
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, 2522 NSW, Australia
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Poder J, Cutajar D, Guatelli S, Petasecca M, Howie A, Bucci J, Rosenfeld A. HDR brachytherapy in vivo source position verification using a 2D diode array: A Monte Carlo study. J Appl Clin Med Phys 2018; 19:163-172. [PMID: 29855128 PMCID: PMC6036394 DOI: 10.1002/acm2.12360] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 03/21/2018] [Accepted: 04/18/2018] [Indexed: 11/23/2022] Open
Abstract
PURPOSE This study aims to assess the accuracy of source position verification during high-dose rate (HDR) prostate brachytherapy using a novel, in-house developed two-dimensional (2D) diode array (the Magic Plate), embedded exactly below the patient within a carbon fiber couch. The effect of tissue inhomogeneities on source localization accuracy is examined. METHOD Monte Carlo (MC) simulations of 12 source positions from a HDR prostate brachytherapy treatment were performed using the Geant4 toolkit. An Ir-192 Flexisource (Isodose Control, Veenendaal, the Netherlands) was simulated inside a voxelized patient geometry, and the dose deposited in each detector of the Magic Plate evaluated. The dose deposited in each detector was then used to localize the source position using a proprietary reconstruction algorithm. RESULTS The accuracy of source position verification using the Magic Plate embedded in the patient couch was found to be affected by the tissue inhomogeneities within the patient, with an average difference of 2.1 ± 0.8 mm (k = 1) between the Magic Plate predicted and known source positions. Recalculation of the simulations with all voxels assigned a density of water improved this verification accuracy to within 1 mm. CONCLUSION Source position verification using the Magic Plate during a HDR prostate brachytherapy treatment was examined using MC simulations. In a homogenous geometry (water), the Magic Plate was able to localize the source to within 1 mm, however, the verification accuracy was negatively affected by inhomogeneities; this can be corrected for by using density information obtained from CT, making the proposed tool attractive for use as a real-time in vivo quality assurance (QA) device in HDR brachytherapy for prostate cancer.
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Affiliation(s)
- Joel Poder
- Centre of Medical Radiation PhysicsUniversity of WollongongWollongongNSWAustralia
- St George Hospital Cancer Care CentreKogarahNSWAustralia
| | - Dean Cutajar
- Centre of Medical Radiation PhysicsUniversity of WollongongWollongongNSWAustralia
- St George Hospital Cancer Care CentreKogarahNSWAustralia
| | - Susanna Guatelli
- Centre of Medical Radiation PhysicsUniversity of WollongongWollongongNSWAustralia
| | - Marco Petasecca
- Centre of Medical Radiation PhysicsUniversity of WollongongWollongongNSWAustralia
| | - Andrew Howie
- St George Hospital Cancer Care CentreKogarahNSWAustralia
| | - Joseph Bucci
- St George Hospital Cancer Care CentreKogarahNSWAustralia
| | - Anatoly Rosenfeld
- Centre of Medical Radiation PhysicsUniversity of WollongongWollongongNSWAustralia
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Khan M, Heilemann G, Kuess P, Georg D, Berg A. The impact of the oxygen scavenger on the dose-rate dependence and dose sensitivity of MAGIC type polymer gels. ACTA ACUST UNITED AC 2018. [DOI: 10.1088/1361-6560/aab00b] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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26
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Pasler M, Hernandez V, Jornet N, Clark CH. Novel methodologies for dosimetry audits: Adapting to advanced radiotherapy techniques. Phys Imaging Radiat Oncol 2018; 5:76-84. [PMID: 33458373 PMCID: PMC7807589 DOI: 10.1016/j.phro.2018.03.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 03/08/2018] [Accepted: 03/08/2018] [Indexed: 11/25/2022] Open
Abstract
With new radiotherapy techniques, treatment delivery is becoming more complex and accordingly, these treatment techniques require dosimetry audits to test advanced aspects of the delivery to ensure best practice and safe patient treatment. This review of novel methodologies for dosimetry audits for advanced radiotherapy techniques includes recent developments and future techniques to be applied in dosimetry audits. Phantom-based methods (i.e. phantom-detector combinations) including independent audit equipment and local measurement equipment as well as phantom-less methods (i.e. portal dosimetry, transmission detectors and log files) are presented and discussed. Methodologies for both conventional linear accelerator (linacs) and new types of delivery units, i.e. Tomotherapy, stereotactic devices and MR-linacs, are reviewed. Novel dosimetry audit techniques such as portal dosimetry or log file evaluation have the potential to allow parallel auditing (i.e. performing an audit at multiple institutions at the same time), automation of data analysis and evaluation of multiple steps of the radiotherapy treatment chain. These methods could also significantly reduce the time needed for audit and increase the information gained. However, to maximise the potential, further development and harmonisation of dosimetry audit techniques are required before these novel methodologies can be applied.
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Affiliation(s)
- Marlies Pasler
- Lake Constance Radiation Oncology Center Singen-Friedrichshafen, Germany
| | - Victor Hernandez
- Department of Medical Physics, Hospital Sant Joan de Reus, IISPV, Tarragona, Spain
| | - Núria Jornet
- Servei de RadiofísicaiRadioprotecció, Hospital de la Santa CreuiSant Pau, Spain
| | - Catharine H. Clark
- Department of Medical Physics, Royal Surrey County Hospital, Guildford, Surrey, UK
- Metrology for Medical Physics (MEMPHYS), National Physical Laboratory, Teddington, Middlesex, UK
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Biasi G, Petasecca M, Guatelli S, Hardcastle N, Carolan M, Perevertaylo V, Kron T, Rosenfeld AB. A novel high-resolution 2D silicon array detector for small field dosimetry with FFF photon beams. Phys Med 2017; 45:117-126. [PMID: 29472075 DOI: 10.1016/j.ejmp.2017.12.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 12/13/2017] [Accepted: 12/15/2017] [Indexed: 11/19/2022] Open
Abstract
PURPOSE Flattening filter free (FFF) beams are increasingly being considered for stereotactic radiotherapy (SRT). For the first time, the performance of a monolithic silicon array detector under 6 and 10 MV FFF beams was evaluated. The dosimeter, named "Octa" and designed by the Centre for Medical Radiation Physics (CMRP), was tested also under flattened beams for comparison. METHODS Output factors (OFs), percentage depth-dose (PDD), dose profiles (DPs) and dose per pulse (DPP) dependence were investigated. Results were benchmarked against commercially available detectors for small field dosimetry. RESULTS The dosimeter was shown to be a 'correction-free' silicon array detector for OFs and PDD measurements for all the beam qualities investigated. Measured OFs were accurate within 3% and PDD values within 2% compared against the benchmarks. Cross-plane, in-plane and diagonal DPs were measured simultaneously with high spatial resolution (0.3 mm) and real time read-out. A DPP dependence (24% at 0.021 mGy/pulse relative to 0.278 mGy/pulse) was found and could be easily corrected for in the case of machine specific quality assurance applications. CONCLUSIONS Results were consistent with those for monolithic silicon array detectors designed by the CMRP and previously characterized under flattened beams only, supporting the robustness of this technology for relative dosimetry for a wide range of beam qualities and dose per pulses. In contrast to its predecessors, the design of the Octa offers an exhaustive high-resolution 2D dose map characterization, making it a unique real-time radiation detector for small field dosimetry for field sizes up to 3 cm side.
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Affiliation(s)
- G Biasi
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - M Petasecca
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - S Guatelli
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - N Hardcastle
- Peter MacCallum Cancer Centre, Melbourne, Australia
| | - M Carolan
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia; Illawarra Cancer Care Centre, Wollongong Hospital, Wollongong, NSW, Australia
| | | | - T Kron
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia; Peter MacCallum Cancer Centre, Melbourne, Australia; Sir Peter MacCallum Cancer Institute, University of Melbourne, Australia
| | - A B Rosenfeld
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia.
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Marrazzo L, Arilli C, Pasler M, Kusters M, Canters R, Fedeli L, Calusi S, Casati M, Talamonti C, Simontacchi G, Livi L, Pallotta S. Real-time beam monitoring for error detection in IMRT plans and impact on dose-volume histograms : A multi-center study. Strahlenther Onkol 2017; 194:243-254. [PMID: 29255923 DOI: 10.1007/s00066-017-1245-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 11/25/2017] [Indexed: 11/26/2022]
Abstract
PURPOSE This study aimed to test the sensitivity of a transmission detector for online dose monitoring of intensity-modulated radiation therapy (IMRT) for detecting small delivery errors. Furthermore, the correlation of changes in detector output induced by small delivery errors with other metrics commonly employed to quantify the deviations between calculated and delivered dose distributions was investigated. METHODS Transmission detector measurements were performed at three institutions. Seven types of errors were induced in nine clinical step-and-shoot (S&S) IMRT plans by modifying the number of monitor units (MU) and introducing small deviations in leaf positions. Signal reproducibility was investigated for short- and long-term stability. Calculated dose distributions were compared in terms of γ passing rates and dose-volume histogram (DVH) metrics (e.g., Dmean, Dx%, Vx%). The correlation between detector signal variations, γ passing rates, and DVH parameters was investigated. RESULTS Both short- and long-term reproducibility was within 1%. Dose variations down to 1 MU (∆signal 1.1 ± 0.4%) as well as changes in field size and positions down to 1 mm (∆signal 2.6 ± 1.0%) were detected, thus indicating high error-detection sensitivity. A moderate correlation of detector signal was observed with γ passing rates (R2 = 0.57-0.70), while a good correlation was observed with DVH metrics (R2 = 0.75-0.98). CONCLUSION The detector is capable of detecting small delivery errors in MU and leaf positions, and is thus a highly sensitive dose monitoring device for S&S IMRT for clinical practice. The results of this study indicate a good correlation of detector signal with DVH metrics; therefore, clinical action levels can be defined based on the presented data.
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Affiliation(s)
- Livia Marrazzo
- Medical Physic Unit, Careggi University Hospital, Largo Brambilla 3, 50134, Florence, Italy.
| | - Chiara Arilli
- Medical Physic Unit, Careggi University Hospital, Largo Brambilla 3, 50134, Florence, Italy
| | - Marlies Pasler
- Lake Constance Radiation Oncology Center, Singen-Friedrichshafen, Germany
| | - Martijn Kusters
- Department of Radiation Oncology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Richard Canters
- Department of Radiation Oncology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Luca Fedeli
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
| | - Silvia Calusi
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
| | - Marta Casati
- Medical Physic Unit, Careggi University Hospital, Largo Brambilla 3, 50134, Florence, Italy
| | - Cinzia Talamonti
- Medical Physic Unit, Careggi University Hospital, Largo Brambilla 3, 50134, Florence, Italy
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
| | | | - Lorenzo Livi
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
- Radiation Oncology Unit, Careggi University Hospital, Florence, Italy
| | - Stefania Pallotta
- Medical Physic Unit, Careggi University Hospital, Largo Brambilla 3, 50134, Florence, Italy
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
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Impact of a monolithic silicon detector operating in transmission mode on clinical photon beams. Phys Med 2017; 43:114-119. [PMID: 29195553 DOI: 10.1016/j.ejmp.2017.10.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 10/18/2017] [Accepted: 10/20/2017] [Indexed: 11/21/2022] Open
Abstract
PURPOSE To investigate the effect on surface dose, as a function of different field sizes and distances from the solid water phantom to transmission detector (Dsd), of using the monolithic silicon detector MP512T in transmission mode. METHODS The influence of operating the MP512T in transmission mode on the surface dose of a phantom for SSD 100cm was evaluated by using a Markus IC. The MP512T was fixed to an adjustable stand holder and was positioned at different Dsd, ranging from 0.3 to 24 cm. For each Dsd, measurements were carried out for irradiation field sizes of 5 × 5cm2, 8 × 8 cm2 and 10 × 10 cm2. Measurements were obtained under two different operational setups, (i) with the MP512T face-up and (ii) with the MP512T face-down. In addition, the transmission factors for the MP512T and the printed circuit board were only evaluated using a Farmer IC. RESULTS For all Dsd and all field sizes, the MP512T led to the surface dose increasing by less than 25% when in the beam. For Dsd >18 cm the surface dose increase is less than 5%, and negligible for field size 5 × 5 cm2. The difference in the surface dose perturbation for the MP512T operating face up or operating face down is negligible (<2%) for all field sizes. The transmission factor of the MP512T ranged from 1.020 to 0.9950 for all measured Dsd and field sizes. CONCLUSION The study demonstrated that positioning the MP512T in air between the Linac head and the phantom produced negligible perturbation of the surface dose for Dsd >18 cm, and was completely transparent for 6 MV photon beams.
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Cheung JP, Perez-Andujar A, Morin O. Characterization of the effect of a new commercial transmission detector on radiation therapy beams. Pract Radiat Oncol 2017; 7:e559-e567. [PMID: 28666901 DOI: 10.1016/j.prro.2017.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 03/07/2017] [Accepted: 04/05/2017] [Indexed: 10/19/2022]
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Semiconductor real-time quality assurance dosimetry in brachytherapy. Brachytherapy 2017; 17:133-145. [PMID: 28964727 DOI: 10.1016/j.brachy.2017.08.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 08/22/2017] [Accepted: 08/28/2017] [Indexed: 11/23/2022]
Abstract
With the increase in complexity of brachytherapy treatments, there has been a demand for the development of sophisticated devices for delivery verification. The Centre for Medical Radiation Physics (CMRP), University of Wollongong, has demonstrated the applicability of semiconductor devices to provide cost-effective real-time quality assurance for a wide range of brachytherapy treatment modalities. Semiconductor devices have shown great promise to the future of pretreatment and in vivo quality assurance in a wide range of brachytherapy treatments, from high-dose-rate (HDR) prostate procedures to eye plaque treatments. The aim of this article is to give an insight into several semiconductor-based dosimetry instruments developed by the CMRP. Applications of these instruments are provided for breast and rectal wall in vivo dosimetry in HDR brachytherapy, urethral in vivo dosimetry in prostate low-dose-rate (LDR) brachytherapy, quality assurance of HDR brachytherapy afterloaders, HDR pretreatment plan verification, and real-time verification of LDR and HDR source dwell positions.
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Pasler M, Michel K, Marrazzo L, Obenland M, Pallotta S, Björnsgard M, Lutterbach J. Error detection capability of a novel transmission detector: a validation study for online VMAT monitoring. ACTA ACUST UNITED AC 2017; 62:7440-7450. [DOI: 10.1088/1361-6560/aa7dc7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Influence of the Integral Quality Monitor transmission detector on high energy photon beams: A multi-centre study. Z Med Phys 2017; 27:232-242. [DOI: 10.1016/j.zemedi.2016.10.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 10/02/2016] [Accepted: 10/03/2016] [Indexed: 11/23/2022]
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Vicoroski N, Espinoza A, Duncan M, Oborn BM, Carolan M, Metcalfe P, Menichelli D, Perevertaylo VL, Lerch MLF, Rosenfeld AB, Petasecca M. Development of a silicon diode detector for skin dosimetry in radiotherapy. Med Phys 2017; 44:5402-5412. [DOI: 10.1002/mp.12469] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 06/14/2017] [Accepted: 06/28/2017] [Indexed: 11/06/2022] Open
Affiliation(s)
- Nikolina Vicoroski
- Centre for Medical Radiation Physics; University of Wollongong; Wollongong NSW 2500 Australia
| | - Anthony Espinoza
- Centre for Medical Radiation Physics; University of Wollongong; Wollongong NSW 2500 Australia
| | - Mitchell Duncan
- Centre for Medical Radiation Physics; University of Wollongong; Wollongong NSW 2500 Australia
| | - Bradley M. Oborn
- Centre for Medical Radiation Physics; University of Wollongong; Wollongong NSW 2500 Australia
- Illawarra Cancer Care Centre; Wollongong Hospital; Wollongong NSW 2500 Australia
| | - Martin Carolan
- Centre for Medical Radiation Physics; University of Wollongong; Wollongong NSW 2500 Australia
- Illawarra Cancer Care Centre; Wollongong Hospital; Wollongong NSW 2500 Australia
| | - Peter Metcalfe
- Centre for Medical Radiation Physics; University of Wollongong; Wollongong NSW 2500 Australia
- Illawarra Health and Medical Research Institute - IHMRI; Wollongong NSW 2500 Australia
| | | | | | - Michael L. F. Lerch
- Centre for Medical Radiation Physics; University of Wollongong; Wollongong NSW 2500 Australia
- Illawarra Health and Medical Research Institute - IHMRI; Wollongong NSW 2500 Australia
| | - Anatoly B. Rosenfeld
- Centre for Medical Radiation Physics; University of Wollongong; Wollongong NSW 2500 Australia
- Illawarra Health and Medical Research Institute - IHMRI; Wollongong NSW 2500 Australia
| | - Marco Petasecca
- Centre for Medical Radiation Physics; University of Wollongong; Wollongong NSW 2500 Australia
- Illawarra Health and Medical Research Institute - IHMRI; Wollongong NSW 2500 Australia
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Hoffman D, Chung E, Hess C, Stern R, Benedict S. Characterization and evaluation of an integrated quality monitoring system for online quality assurance of external beam radiation therapy. J Appl Clin Med Phys 2016; 18:40-48. [PMID: 28291937 PMCID: PMC5689870 DOI: 10.1002/acm2.12014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 09/10/2016] [Indexed: 11/16/2022] Open
Abstract
Purpose The aim of this work was to comprehensively evaluate a new large field ion chamber transmission detector, Integral Quality Monitor (IQM), for online external photon beam verification and quality assurance. The device is designed to be mounted on the linac accessory tray to measure and verify photon energy, field shape, gantry position, and fluence before and during patient treatment. Methods Our institution evaluated the newly developed ion chamber's effect on photon beam fluence, response to dose, detection of photon fluence modification, and the accuracy of the integrated barometer, thermometer, and inclinometer. The detection of photon fluence modifications was performed by measuring 6 MV with fields of 10 cm × 10 cm and 1 cm × 1 cm “correct” beam, and then altering the beam modifiers to simulate minor and major delivery deviations. The type and magnitude of the deviations selected for evaluation were based on the specifications for photon output and MLC position reported in AAPM Task Group Report 142. Additionally, the change in ion chamber signal caused by a simulated IMRT delivery error is evaluated. Results The device attenuated 6 MV, 10 MV, and 15 MV photon beams by 5.43 ± 0.02%, 4.60 ± 0.02%, and 4.21 ± 0.03%, respectively. Photon beam profiles were altered with the IQM by < 1.5% in the nonpenumbra regions of the beams. The photon beam profile for a 1 cm × 1 cm2 fields were unchanged by the presence of the device. The large area ion chamber measurements were reproducible on the same day with a 0.14% standard deviation and stable over 4 weeks with a 0.47% SD. The ion chamber's dose–response was linear (R2 = 0.99999). The integrated thermometer agreed to a calibrated thermometer to within 1.0 ± 0.7°C. The integrated barometer agreed to a mercury barometer to within 2.3 ± 0.4 mmHg. The integrated inclinometer gantry angle measurement agreed with the spirit level at 0 and 180 degrees within 0.03 ± 0.01 degrees and 0.27 ± 0.03 at 90 and 270 degrees. For the collimator angle measurement, the IQM inclinometer agreed with a plum‐bob within 0.3 ± 0.2 degrees. The simulated IMRT error increased the ion chamber signal by a factor of 11–238 times the baseline measurement for each segment. Conclusions The device signal was dependent on variations in MU delivered, field position, single MLC leaf position, and nominal photon energy for both the 1 cm × 1 cm and 10 cm × 10 cm fields. This detector has demonstrated utility repeated photon beam measurement, including in IMRT and small field applications.
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Affiliation(s)
- David Hoffman
- Department of Radiation Medicine and Applied Sciences, University of California, San Diego, CA, USA
| | - Eunah Chung
- Department of Radiation Oncology, Samsung Medical Center, Seoul, South Korea
| | - Clayton Hess
- Pediatric Radiation Oncology, Harvard Medical School, Boston, MA, USA
| | - Robin Stern
- Department of Radiation Oncology, University of California, Davis, Sacramento, CA, USA
| | - Stanley Benedict
- Department of Radiation Oncology, University of California, Davis, Sacramento, CA, USA
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Initial experiments with gel-water: towards MRI-linac dosimetry and imaging. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2016; 39:921-932. [PMID: 27815727 DOI: 10.1007/s13246-016-0495-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 10/25/2016] [Indexed: 10/20/2022]
Abstract
Tracking the position of a moving radiation detector in time and space during data acquisition can replicate 4D image-guided radiotherapy (4DIGRT). Magnetic resonance imaging (MRI)-linacs need MRI-visible detectors to achieve this, however, imaging solid phantoms is an issue. Hence, gel-water, a material that provides signal for MRI-visibility, and which will in future work, replace solid water for an MRI-linac 4DIGRT quality assurance tool, is discussed. MR and CT images of gel-water were acquired for visualisation and electron density verification. Characterisation of gel-water at 0 T was compared to Gammex-RMI solid water, using MagicPlate-512 (M512) and RMI Attix chamber; this included percentage depth dose, tissue-phantom ratio (TPR20/10), tissue-maximum ratio (TMR), profiles, output factors, and a gamma analysis to investigate field penumbral differences. MR images of a non-powered detector in gel-water demonstrated detector visualisation. The CT-determined gel-water electron density agreed with the calculated value of 1.01. Gel-water depth dose data demonstrated a maximum deviation of 0.7% from solid water for M512 and 2.4% for the Attix chamber, and by 2.1% for TPR20/10 and 1.0% for TMR. FWHM and output factor differences between materials were ≤0.3 and ≤1.4%. M512 data passed gamma analysis with 100% within 2%, 2 mm tolerance for multileaf collimator defined fields. Gel-water was shown to be tissue-equivalent for dosimetry and a feasible option to replace solid water.
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Li T, Wu QJ, Matzen T, Yin FF, O'Daniel JC. Diode-based transmission detector for IMRT delivery monitoring: a validation study. J Appl Clin Med Phys 2016; 17:235-244. [PMID: 27685115 PMCID: PMC5874094 DOI: 10.1120/jacmp.v17i5.6204] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 06/02/2016] [Accepted: 05/02/2016] [Indexed: 11/23/2022] Open
Abstract
The purpose of this work was to evaluate the potential of a new transmission detector for real‐time quality assurance of dynamic‐MLC‐based radiotherapy. The accuracy of detecting dose variation and static/dynamic MLC position deviations was measured, as well as the impact of the device on the radiation field (surface dose, transmission). Measured dose variations agreed with the known variations within 0.3%. The measurement of static and dynamic MLC position deviations matched the known deviations with high accuracy (0.7–1.2 mm). The absorption of the device was minimal (∼ 1%). The increased surface dose was small (1%–9%) but, when added to existing collimator scatter effects could become significant at large field sizes (≥30×30 cm2). Overall the accuracy and speed of the device show good potential for real‐time quality assurance. PACS number(s): 87.55.Qr
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Alrowaili ZA, Lerch MLF, Petasecca M, Carolan MG, Metcalfe PE, Rosenfeld AB. Beam perturbation characteristics of a 2D transmission silicon diode array, Magic Plate. J Appl Clin Med Phys 2016; 17:85-98. [PMID: 27074475 PMCID: PMC5874939 DOI: 10.1120/jacmp.v17i2.5932] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 12/11/2015] [Accepted: 12/01/2015] [Indexed: 11/23/2022] Open
Abstract
The main objective of this study is to demonstrate the performance characteristics of the Magic Plate (MP) system when operated upstream of the patient in transmission mode (MPTM). The MPTM is an essential component of a real‐time QA system designed for operation during radiotherapy treatment. Of particular interest is a quantitative study into the influence of the MP on the radiation beam quality at several field sizes and linear accelerator potential differences. The impact is measured through beam perturbation effects such as changes in the skin dose and/or percentage depth dose (PDD) (both in and out of field). The MP was placed in the block tray of a Varian linac head operated at 6, 10 and 18 MV beam energy. To optimize the MPTM operational setup, two conditions were investigated and each setup was compared to the case where no MP is positioned in place (i.e., open field): (i) MPTM alone and (ii) MPTM with a thin passive contamination electron filter. The in‐field and out‐of‐field surface doses of a solid water phantom were investigated for both setups using a Markus plane parallel (Model N23343) and Attix parallel‐plate, MRI model 449 ionization chambers. In addition, the effect on the 2D dose distribution measured by the Delta4 QA system was also investigated. The transmission factor for both of these MPTM setups in the central axis was also investigated using a Farmer ionization chamber (Model 2571A) and an Attix ionization chamber. Measurements were performed for different irradiation field sizes of 5×5 cm2 and 10×10 cm2. The change in the surface dose relative to dmax was measured to be less than 0.5% for the 6 MV, 10 MV, and 18 MV energy beams. Transmission factors measured for both set ups (i & ii above) with 6 MV, 10 MV, and 18 MV at a depth of dmax and a depth of 10 cm were all within 1.6% of open field. The impact of both the bare MPTM and the MPTM with 1 mm buildup on 3D dose distribution in comparison to the open field investigated using the Delta4 system and both the MPTM versions passed standard clinical gamma analysis criteria. Two MPTM operational setups were studied and presented in this article. The results indicate that both versions may be suitable for the new real‐time megavoltage photon treatment delivery QA system under development. However, the bare MPTM appears to be slightly better suited of the two MP versions, as it minimally perturbs the radiation field and does not lead to any significant increase in skin dose to the patient. PACS number(s): 87.50.up, 87.53.Bn, 87.55.N, 87.55.Qr, 87.56.Fc.
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Noel CE, Santanam L, Parikh PJ, Mutic S. Process-based quality management for clinical implementation of adaptive radiotherapy. Med Phys 2015; 41:081717. [PMID: 25086527 DOI: 10.1118/1.4890589] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
PURPOSE Intensity-modulated adaptive radiotherapy (ART) has been the focus of considerable research and developmental work due to its potential therapeutic benefits. However, in light of its unique quality assurance (QA) challenges, no one has described a robust framework for its clinical implementation. In fact, recent position papers by ASTRO and AAPM have firmly endorsed pretreatment patient-specific IMRT QA, which limits the feasibility of online ART. The authors aim to address these obstacles by applying failure mode and effects analysis (FMEA) to identify high-priority errors and appropriate risk-mitigation strategies for clinical implementation of intensity-modulated ART. METHODS An experienced team of two clinical medical physicists, one clinical engineer, and one radiation oncologist was assembled to perform a standard FMEA for intensity-modulated ART. A set of 216 potential radiotherapy failures composed by the forthcoming AAPM task group 100 (TG-100) was used as the basis. Of the 216 failures, 127 were identified as most relevant to an ART scheme. Using the associated TG-100 FMEA values as a baseline, the team considered how the likeliness of occurrence (O), outcome severity (S), and likeliness of failure being undetected (D) would change for ART. New risk priority numbers (RPN) were calculated. Failures characterized by RPN ≥ 200 were identified as potentially critical. RESULTS FMEA revealed that ART RPN increased for 38% (n = 48/127) of potential failures, with 75% (n = 36/48) attributed to failures in the segmentation and treatment planning processes. Forty-three of 127 failures were identified as potentially critical. Risk-mitigation strategies include implementing a suite of quality control and decision support software, specialty QA software/hardware tools, and an increase in specially trained personnel. CONCLUSIONS Results of the FMEA-based risk assessment demonstrate that intensity-modulated ART introduces different (but not necessarily more) risks than standard IMRT and may be safely implemented with the proper mitigations.
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Affiliation(s)
- Camille E Noel
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Lakshmi Santanam
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Parag J Parikh
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Sasa Mutic
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63110
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Espinoza A, Petasecca M, Fuduli I, Howie A, Bucci J, Corde S, Jackson M, Lerch MLF, Rosenfelda AB. The evaluation of a 2D diode array in “magic phantom” for use in high dose rate brachytherapy pretreatment quality assurance. Med Phys 2015; 42:663-673. [PMID: 25771556 DOI: 10.1118/1.4905233] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 12/09/2014] [Accepted: 12/16/2014] [Indexed: 11/07/2022] Open
Abstract
PURPOSE High dose rate (HDR) brachytherapy is a treatment method that is used increasingly worldwide. The development of a sound quality assurance program for the verification of treatment deliveries can be challenging due to the high source activity utilized and the need for precise measurements of dwell positions and times. This paper describes the application of a novel phantom, based on a 2D 11 × 11 diode array detection system, named “magic phantom” (MPh), to accurately measure plan dwell positions and times, compare them directly to the treatment plan, determine errors in treatment delivery, and calculate absorbed dose. METHODS The magic phantom system was CT scanned and a 20 catheter plan was generated to simulate a nonspecific treatment scenario. This plan was delivered to the MPh and, using a custom developed software suite, the dwell positions and times were measured and compared to the plan. The original plan was also modified, with changes not disclosed to the primary authors, and measured again using the device and software to determine the modifications. A new metric, the “position–time gamma index,” was developed to quantify the quality of a treatment delivery when compared to the treatment plan. The MPh was evaluated to determine the minimum measurable dwell time and step size. The incorporation of the TG-43U1 formalism directly into the software allows for dose calculations to be made based on the measured plan. The estimated dose distributions calculated by the software were compared to the treatment plan and to calibrated EBT3 film, using the 2D gamma analysis method. RESULTS For the original plan, the magic phantom system was capable of measuring all dwell points and dwell times and the majority were found to be within 0.93 mm and 0.25 s, respectively, from the plan. By measuring the altered plan and comparing it to the unmodified treatment plan, the use of the position–time gamma index showed that all modifications made could be readily detected. The MPh was able to measure dwell times down to 0.067 ± 0.001 s and planned dwell positions separated by 1 mm. The dose calculation carried out by the MPh software was found to be in agreement with values calculated by the treatment planning system within 0.75%. Using the 2D gamma index, the dose map of the MPh plane and measured EBT3 were found to have a pass rate of over 95% when compared to the original plan. CONCLUSIONS The application of this magic phantom quality assurance system to HDR brachytherapy has demonstrated promising ability to perform the verification of treatment plans, based upon the measured dwell positions and times. The introduction of the quantitative position–time gamma index allows for direct comparison of measured parameters against the plan and could be used prior to patient treatment to ensure accurate delivery.
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Espinoza A, Petasecca M, Cutajar D, Fuduli I, Howie A, Bucci J, Corde S, Jackson M, Zaider M, Lerch MLF, Rosenfeld AB. Pretreatment verification of high dose rate brachytherapy plans using the ‘magic phantom’ system. Biomed Phys Eng Express 2015. [DOI: 10.1088/2057-1976/1/2/025201] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Petasecca M, Alhujaili S, Aldosari AH, Fuduli I, Newall M, Porumb CS, Carolan M, Nitschke K, Lerch MLF, Kalliopuska J, Perevertaylo V, Rosenfeld AB. Angular independent silicon detector for dosimetry in external beam radiotherapy. Med Phys 2015; 42:4708-18. [DOI: 10.1118/1.4926778] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Petasecca M, Newall MK, Booth JT, Duncan M, Aldosari AH, Fuduli I, Espinoza AA, Porumb CS, Guatelli S, Metcalfe P, Colvill E, Cammarano D, Carolan M, Oborn B, Lerch MLF, Perevertaylo V, Keall PJ, Rosenfeld AB. MagicPlate-512: A 2D silicon detector array for quality assurance of stereotactic motion adaptive radiotherapy. Med Phys 2015; 42:2992-3004. [DOI: 10.1118/1.4921126] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Gargett M, Oborn B, Metcalfe P, Rosenfeld A. Monte Carlo simulation of the dose response of a novel 2D silicon diode array for use in hybrid MRI-LINAC systems. Med Phys 2015; 42:856-65. [DOI: 10.1118/1.4905108] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Fuduli I, Newall M, Espinoza A, Porumb C, Carolan M, Lerch M, Metcalfe P, Rosenfeld A, Petasecca M. Multichannel Data Acquisition System comparison for Quality Assurance in external beam radiation therapy. RADIAT MEAS 2014. [DOI: 10.1016/j.radmeas.2014.05.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Jong WL, Wong JHD, Ung NM, Ng KH, Ho GF, Cutajar DL, Rosenfeld AB. Characterization of MOSkin detector for in vivo skin dose measurement during megavoltage radiotherapy. J Appl Clin Med Phys 2014; 15:4869. [PMID: 25207573 PMCID: PMC5711095 DOI: 10.1120/jacmp.v15i5.4869] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Revised: 05/19/2014] [Accepted: 05/14/2014] [Indexed: 11/25/2022] Open
Abstract
In vivo dosimetry is important during radiotherapy to ensure the accuracy of the dose delivered to the treatment volume. A dosimeter should be characterized based on its application before it is used for in vivo dosimetry. In this study, we characterize a new MOSFET‐based detector, the MOSkin detector, on surface for in vivo skin dosimetry. The advantages of the MOSkin detector are its water equivalent depth of measurement of 0.07 mm, small physical size with submicron dosimetric volume, and the ability to provide real‐time readout. A MOSkin detector was calibrated and the reproducibility, linearity, and response over a large dose range to different threshold voltages were determined. Surface dose on solid water phantom was measured using MOSkin detector and compared with Markus ionization chamber and GAFCHROMIC EBT2 film measurements. Dependence in the response of the MOSkin detector on the surface of solid water phantom was also tested for different (i) source to surface distances (SSDs); (ii) field sizes; (iii) surface dose; (iv) radiation incident angles; and (v) wedges. The MOSkin detector showed excellent reproducibility and linearity for dose range of 50 cGy to 300 cGy. The MOSkin detector showed reliable response to different SSDs, field sizes, surface, radiation incident angles, and wedges. The MOSkin detector is suitable for in vivo skin dosimetry. PACS number: 87.55.Qr
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Affiliation(s)
- Wei Loong Jong
- Clinical Oncology Unit, Faculty of Medicine, University of Malaya.
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Aldosari AH, Petasecca M, Espinoza A, Newall M, Fuduli I, Porumb C, Alshaikh S, Alrowaili ZA, Weaver M, Metcalfe P, Carolan M, Lerch MLF, Perevertaylo V, Rosenfeld AB. A two dimensional silicon detectors array for quality assurance in stereotactic radiotherapy: MagicPlate-512. Med Phys 2014; 41:091707. [DOI: 10.1118/1.4892384] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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Espinoza A, Beeksma B, Petasecca M, Fuduli I, Porumb C, Cutajar D, Corde S, Jackson M, Lerch MLF, Rosenfeld AB. The feasibility study and characterization of a two-dimensional diode array in “magic phantom” for high dose rate brachytherapy quality assurance. Med Phys 2013; 40:111702. [DOI: 10.1118/1.4822736] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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