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K E R, Krishnan M. Surface dose measurement and comparison between TLD and OSLD during modified re constructive mastectomy irradiation. Biomed Phys Eng Express 2024; 10:045025. [PMID: 38714180 DOI: 10.1088/2057-1976/ad47fd] [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: 12/13/2023] [Accepted: 05/07/2024] [Indexed: 05/09/2024]
Abstract
Radiotherapy (RT) is one of the major treatment modalities among surgery and chemotherapy for carcinoma breast. The surface dose study of modified reconstructive constructive Mastectomy (MRM) breast is important due to the heterogeneity in the body contour and the conventional treatment angle to save the lungs and heart from the radiation. These angular entries of radiation beam cause an unpredictable dose deposition on the body surface, which has to be monitored. Thermoluminescent dosimeter (TLD) or optically stimulated luminescent dosimeter (nano OSLD) are commonly preferable dosimeters for this purpose. The surface dose response of TLD and nano OSLD during MRM irradiation has been compared with the predicted dose from the treatment planning system (TPS). The study monitored 100 MRM patients by employing a total 500 dosimeters consisting of TLD (n = 250) and nano OSLD (n = 250), during irradiation from an Elekta Versa HD 6 MV Linear accelerator. The study observed a variance of 3.9% in the dose measurements for TLD and 3.2% for nano OSLD from the planned surface dose, with a median percentage dose of 44.02 for nano OSLD and 40.30 for TLD (p value 0.01). There was no discernible evidence of variation in dose measurements attributable to differences in field size or from patient to patient. Additionally, no variation was observed in dose measurements when comparing the placement of the dosimeter from central to off-centre positions. In comparison, a minor difference in dose measurements were noted between TLD and nano OSLD, The study's outcomes support the applicability of both TLD and nano OSLD as effective dosimeters during MRM breast irradiation for surface dose evaluation.
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Affiliation(s)
- Ratheesh K E
- Department of Medical Physics, Centre for Interdisciplinary Research, D. Y. Patil Education Society (Deemed to be University), Kolhapur, Maharashtra, India
| | - Mayakannan Krishnan
- Department of Medical Physics, Centre for Interdisciplinary Research, D. Y. Patil Education Society (Deemed to be University), Kolhapur, Maharashtra, India
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Ratheesh KE, Mayakannan K. Angular dependence of the TL and OSL dosimeters in the clinical 6 MV photon Beam. Appl Radiat Isot 2023; 202:111073. [PMID: 37890243 DOI: 10.1016/j.apradiso.2023.111073] [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: 05/06/2023] [Revised: 10/05/2023] [Accepted: 10/16/2023] [Indexed: 10/29/2023]
Abstract
The angular response of luminescent dosimeters (LD), in particular TLD and OSLD, has been compared by applying 6 MV X-ray photons from Versa HD clinical linear accelerator. The study admitted for the irradiation of TLD (n = 475) and OSLD (n = 475) under phantom set up in various gantry angles from 00 to ±900 and various field sizes from 10 x 10 cm2 to 30 x 30 cm2. The variance in the output was observed between 4.4% for TLD and 3.9% for OSLD. A significant deviation from the desired output was detected, towards the angle of incidents, at ±800 to ±900. Additionally, there is no evidence of variation in the dose measurement due to the difference in field size. These results demonstrate a good approximation to the vendor-specified tolerance limits, justifying the use of these LDs within angular incidents of radiation up to ±700. The TLD and OSLD better dose-response is achieved to a gantry angle up to ±700 from the perpendicular incidents. The result shows that both TLD and OSLD could be used as dosimeters for a treatment field that does not extend beyond ±700 beam angle.
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Affiliation(s)
- K E Ratheesh
- D. Y. Patil Education Society (Deemed to be University), Kolhapur, Maharashtra, India
| | - Krishnan Mayakannan
- D. Y. Patil Education Society (Deemed to be University), Kolhapur, Maharashtra, India.
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Assessment of Fetal Dose and Health Effect to the Fetus from Breast Cancer Radiotherapy during Pregnancy. Life (Basel) 2022; 12:life12010084. [PMID: 35054476 PMCID: PMC8780279 DOI: 10.3390/life12010084] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/30/2021] [Accepted: 01/05/2022] [Indexed: 01/26/2023] Open
Abstract
Decision for radiotherapy during the first trimester of pregnancy may occur, as patients may not realize their pregnancy at the very early stage. Since radiation dose can affect fetal development, the aim of this study was to evaluate fetal dose and associated deterministic effects and risks to the fetus from breast cancer radiotherapy of an 8-week pregnant patient. PHITS (Particle and Heavy Ion Transport code System) Monte Carlo simulation and the J-45 computational pregnancy phantom were used to simulate breast cancer radiotherapy from a 6 MV TrueBeam linear accelerator using the three dimensional-conformal radiotherapy (3D-CRT) technique with a prescribed dose to the planning target volume (PTV) of 50 Gy. Once the fetal dose was evaluated, the occurrence of the deterministic effects and risks for developing stochastic effects in the fetus were assessed using the recommendations of NCRP Report No. 174, AAPM Report No. 50, and ICRP Publication 84. The fetal dose was evaluated to be 3.37 ± 2.66 mGy, suggesting that the fetus was expected to have no additional deterministic effects, while the risks for developing cancer and malfunctions were similar to that expected from exposure to background radiation. The comparison with the other studies showed that accurate consideration of fetal position and size was important for dose determination in the fetus, especially at the early pregnancy stage when the fetus is very small.
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Wang L, Qiu G, Yu J, Zhang Q, Man L, Chen L, Zhang X, Ren Q, Xu H, Hua X. Effect of auto flash margin on superficial dose in breast conserving radiotherapy for breast cancer. J Appl Clin Med Phys 2021; 22:60-70. [PMID: 34028963 PMCID: PMC8200433 DOI: 10.1002/acm2.13287] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 02/15/2021] [Accepted: 04/25/2021] [Indexed: 11/13/2022] Open
Abstract
Purpose To investigate the dose‐effect of Auto Flash Margin (AFM) on breast cancer's superficial tissues based on the Treatment Planning System (TPS) in the breast‐conserving radiotherapy plan. Methods A total of 16 breast‐conserving patients with early stage breast cancer were selected, using the X‐ray Voxel Monte Carlo (XVMC) algorithm. Then, every included case plan was designed using a 2 cm‐AFM (the value of AFM is 2 cm) and N‐AFM (without AFM). Under the condition of ensuring the same configuration of #MU and collimator, the absorbed dose after a simulated inspiratory motion was calculated again using the new plan center, which moved backward to the linac source. The dose difference between the measurement points between AFM and N‐AFM groups was compared. Results In the dose results, PTVV50Gy of the AFM group was superior to that of the N‐AFM group, PTVD2%, PTVDmean, Lung_IpsiV20Gy, Lung_IpsiDmean, and BodyDmax. Also, the dose results of the N‐AFM group were significantly higher than those of the AFM group. However, there was no significant difference between Lung_ContraV5Gy, HeartDmean, and Breast_ContraV10Gy in the two groups. In the collimator alignments at the same angle between groups, the AFM group formed an apparent air region outside the collimator compared with the N‐AFM group. In the XVMC algorithm feature parameter, the AFM group had less #MU, higher QE, and slightly longer optimization time. The #segments of both groups were close to the 240 control points preset by the plan. The validation results of EBT3 film in both groups were more significant than 95%, meeting the clinical plan's application requirements. The difference in film results between groups was mainly reflected in the dose distribution at the near‐source. 4DCT was used to summarize the maximum and minimum inspiratory motion distances of 7.31 ± 0.45 and 3.42 ± 0.91 mm respectively. Conclusions These results suggest that the AFM function application could significantly reduce the possibility of insufficient tumor target caused by inspiratory motion and ensure sufficient tumor target exposure.
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Affiliation(s)
- Lu Wang
- Department of Radiotherapy, Anshan Cancer Hospital, Anshan, Liaoning, China
| | - Gang Qiu
- Department of Oncology Ward 2, Hebei General Hospital, Shijiazhuang, Hebei, China
| | - Jianhe Yu
- Department of Oncology Ward 3, Xinghua People's Hospital, Taizhou, Jiangsu, China
| | - Qunhui Zhang
- Surgical oncology, Anshan Cancer Hospital, Anshan, Liaoning, China
| | - Li Man
- Medical oncology, Anshan Cancer Hospital, Anshan, Liaoning, China
| | - Li Chen
- Department of Radiotherapy, Anshan Cancer Hospital, Anshan, Liaoning, China
| | - Xiaoxiao Zhang
- Department of Radiotherapy, Anshan Cancer Hospital, Anshan, Liaoning, China
| | - Qun Ren
- Department of Oncology Ward 3, Xinghua People's Hospital, Taizhou, Jiangsu, China
| | - Hongxia Xu
- Department of Oncology Ward 3, Xinghua People's Hospital, Taizhou, Jiangsu, China
| | - Xiaolong Hua
- Department of Radiotherapy, Xinghua People's Hospital, Taizhou, Jiangsu, China
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Kern A, Bäumer C, Kröninger K, Mertens L, Timmermann B, Walbersloh J, Wulff J. Determination of surface dose in pencil beam scanning proton therapy. Med Phys 2020; 47:2277-2288. [PMID: 32037577 DOI: 10.1002/mp.14086] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 02/03/2020] [Accepted: 02/03/2020] [Indexed: 11/11/2022] Open
Abstract
PURPOSE/OBJECTIVE Quantification of surface dose within the first few hundred water equivalent µm is challenging. Nevertheless, it is of large interest for the proton therapy community to study dose effects in the skin. The experimental determination is affected by the detector properties, such as the detector volume and material. The International Commission on Radiation Units and Measurements in its report 39 recommends assessing the skin dose at a depth of 0.07 mm. The aim of this study is the estimation of the absorbed dose at and around a depth of 70 µm. We used various dosimetric approaches in conjunction with proton pencil beam scanning delivery to determine the skin dose in a clinical setting. MATERIAL/METHODS Five different detectors were tested for determining the surface dose in water: EBT3 and HD-V2 GAFCHROMIC™ radiochromic film, LiF:Mg,Ti thermoluminescent dosimeter, IBA PPC05 plane-parallel ionization chamber, and PTW 23391 extrapolation chamber. The irradiation setup consisted of quasi-monoenergetic scanned proton pencil beams with kinetic energies of 100, 150, and 226.7 MeV, respectively. Radiochromic films were placed within a vertical stack and in wedge geometry and were analyzed with FilmQA Pro™ adopting triple channel dosimetry. The extrapolation chamber PTW 23391, which served as a reference in the current work, was used in a conventional ionization chamber setup with a fixed electrode gap of 2 mm. Three Kapton® entrance windows with thicknesses of 25, 50, and 75 µm were employed. Thermoluminescent dosimeters were provided as powder and were pressed onto a sheet of aluminum. Furthermore, the Monte Carlo code TOol for PArticle Simulation (TOPAS) in version 3.1.p2 was used to model an IBA pencil beam scanning nozzle and score dose to water in a water phantom. RESULTS The resulting depth dose curves were normalized to their 100% dose at the reference depth of 3 cm. We obtained the skin doses with the extrapolation chamber and with TOPAS. For the experimental approach this resulted in 79.7 ± 0.3%, 86.0 ± 0.6%, and 87.1 ± 0.1% for the proton energies 100, 150, and 226.7 MeV, respectively. The results for TOPAS were 80.1 ± 0.2% (100 MeV), 87.1 ± 0.5% (150 MeV), and 86.9 ± 0.4% (226.7 MeV), respectively. Based on the experimental results of the skin dose, we provided a clinically relevant surface extrapolation factor for the common measurement methods. This allows the result of the first measurement depth of a detector to be scaled to the dose at the skin depth. Most practical would be the use of the surface extrapolation factor for the PPC05 chamber, due to its direct reading, the wide availability in clinics and the low uncertainties. The calculated factors were 0.986 ± 0.004 for 100 MeV, 0.961 ± 0.008 for 150 MeV, and 0.963 ± 0.003 for 226.7 MeV. CONCLUSIONS In this study, dissimilar experimental approaches were evaluated with respect to measurements at depths close to the surface. The experimental depth dose curves are in good agreement with the simulation with TOPAS Monte Carlo. To the author's knowledge this was the first experimental determination of the skin dose according to the International Commission on Radiation Units and Measurements 39 definition in proton pencil beam scanning.
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Affiliation(s)
- A Kern
- West German Proton Therapy Center Essen (WPE), Essen, 45147, Germany.,University Hospital Essen, Essen, 45147, Germany.,Experimentelle Physik IV, TU Dortmund University, Dortmund, 44227, Germany.,West German Cancer Center (WTZ), Essen, 45147, Germany
| | - C Bäumer
- West German Proton Therapy Center Essen (WPE), Essen, 45147, Germany.,University Hospital Essen, Essen, 45147, Germany.,Experimentelle Physik IV, TU Dortmund University, Dortmund, 44227, Germany.,West German Cancer Center (WTZ), Essen, 45147, Germany.,German Cancer Consortium (DKTK), Heidelberg, 69120, Germany
| | - K Kröninger
- Experimentelle Physik IV, TU Dortmund University, Dortmund, 44227, Germany
| | - L Mertens
- University Medical Center Mannheim, University of Heidelberg, Mannheim, 68167, Germany
| | - B Timmermann
- West German Proton Therapy Center Essen (WPE), Essen, 45147, Germany.,University Hospital Essen, Essen, 45147, Germany.,West German Cancer Center (WTZ), Essen, 45147, Germany.,German Cancer Consortium (DKTK), Heidelberg, 69120, Germany.,Clinic for Particle Therapy, Essen, 45147, Germany
| | - J Walbersloh
- Materialprüfungsamt Nordrhein-Westfalen, Dortmund, 44287, Germany
| | - J Wulff
- West German Proton Therapy Center Essen (WPE), Essen, 45147, Germany.,University Hospital Essen, Essen, 45147, Germany.,West German Cancer Center (WTZ), Essen, 45147, Germany
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Chow JCL, Owrangi AM. A surface energy spectral study on the bone heterogeneity and beam obliquity using the flattened and unflattened photon beams. Rep Pract Oncol Radiother 2015; 21:63-70. [PMID: 26900360 DOI: 10.1016/j.rpor.2015.11.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 09/30/2015] [Accepted: 11/05/2015] [Indexed: 11/28/2022] Open
Abstract
AIM Using flattened and unflattened photon beams, this study investigated the spectral variations of surface photon energy and energy fluence in the bone heterogeneity and beam obliquity. BACKGROUND Surface dose enhancement is a dosimetric concern when using unflattened photon beam in radiotherapy. It is because the unflattened photon beam contains more low-energy photons which are removed by the flattening filter of the flattened photon beam. MATERIALS AND METHODS We used a water and bone heterogeneity phantom to study the distributions of energy, energy fluence and mean energy of the 6 MV flattened and unflattened photon beams (field size = 10 cm × 10 cm) produced by a Varian TrueBEAM linear accelerator. These elements were calculated at the phantom surfaces using Monte Carlo simulations. The photon energy and energy fluence calculations were repeated with the beam angle turned from 0° to 15°, 30° and 45° in the water and bone phantom. RESULTS Spectral results at the phantom surfaces showed that the unflattened photon beams contained more photons concentrated mainly in the low-energy range (0-2 MeV) than the flattened beams associated with a flattening filter. With a bone layer of 1 cm under the phantom surface and within the build-up region of the 6 MV photon beam, it is found that both the flattened and unflattened beams had slightly less photons in the energy range <0.4 MeV compared to the water phantom. This shows that the presence of the bone decreased the low-energy photon backscatters to the phantom surface. When both the flattened and unflattened photon beams were rotated from 0° to 45°, the number of photon and mean photon energy increased. This indicates that both photon beams became more hardened or penetrate when the beam angle increased. In the presence of bone, the mean energies of both photon beams increased. This is due to the absorption of low-energy photons by the bone, resulting in more beam hardening. CONCLUSIONS This study explores the spectral relationships of surface photon energy and energy fluence with bone heterogeneity and beam obliquity for the flattened and unflattened photon beams. The photon spectral information is important in studies on the patient's surface dose enhancement using unflattened photon beams in radiotherapy.
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Affiliation(s)
- James C L Chow
- Department of Radiation Oncology, University of Toronto, Toronto, ON M5G 2M9, Canada; Radiation Medicine Program, Princess Margaret Caner Center, University Health Network, Toronto, ON M5G 2M9, Canada
| | - Amir M Owrangi
- Department of Radiation Oncology, University of Toronto, Toronto, ON M5G 2M9, Canada; Department of Medical Physics, Sunnybrook Health Sciences Center, Toronto ON M4N 3M5, Canada
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Chow JC, Owrangi AM. Dosimetric dependences of bone heterogeneity and beam angle on the unflattened and flattened photon beams: A Monte Carlo comparison. Radiat Phys Chem Oxf Engl 1993 2014. [DOI: 10.1016/j.radphyschem.2014.03.041] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Evaluating the relevance of dosimetric considerations to patient instructions regarding skin care during radiation therapy. JOURNAL OF RADIOTHERAPY IN PRACTICE 2013. [DOI: 10.1017/s1460396913000241] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
AbstractIntroductionPatient teaching in radiation therapy may include restrictions on applying skin products owing to concerns that the presence of such materials may increase skin dose. These restrictions may create unnecessarily complicated and conflicting self-care instructions.PurposeTo determine what thickness of skin product is necessary to produce a clinically meaningful dose increase to the skin, and provide recommendations for evidence-based patient instructions.MethodsDosimetric measurements and Monte Carlo simulations were used to calculate skin dose under 0–1·5 mm thicknesses of two common classes of skin product for a variety of treatment geometries. The thickness of product required to produce a clinically significant dose increase to the skin was determined.ResultsThe thickness of product required to create a clinically meaningful dose increase was >0·7 mm for 10 × 10 cm2 fields and >1·5 mm for 1 × 1 cm2 fields. A typical application of product would be only 0·3 mm.ConclusionIt seems unrealistic to anticipate patients using sufficiently large quantities of skin product to be of clinical concern. We therefore recommend that there are no dosimetric reasons to restrict the use of these types of skin products during radiation therapy for common treatment scenarios.
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Alnawaf H, Butson M, Yu PKN. Measurement and effects of MOSKIN detectors on skin dose during high energy radiotherapy treatment. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2012; 35:321-8. [PMID: 22972481 DOI: 10.1007/s13246-012-0153-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2012] [Accepted: 06/28/2012] [Indexed: 12/01/2022]
Abstract
During in vivo dosimetry for megavoltage X-ray beams, detectors such as diodes, Thermo luminescent dosimeters (TLD's) and MOSFET devices are placed on the patient's skin. This of course will affect the skin dose delivered during that fraction of the treatment. Whilst the overall impact on increasing skin dose would be minimal, little has been quantified concerning the level of increase in absorbed dose, in vivo dosimeters produce when placed in the beams path. To this extent, measurements have been made and analysis performed on dose changes caused by MOSKIN, MOSFET, skin dose detectors. Maximum increases in skin dose were measured as 15 % for 6 MV X-rays and 10 % for 10 MV X-rays at the active crystal of the MOSKIN device which is the thickest part of the detector. This is compared to 32 and 26 % for a standard 1 mm thick LiF TLD at 10 × 10 cm(2) field size for 6 and 10 MV X-rays respectively. Radiochromic film, EBT2 has been shown to provide a high resolution 2 dimensional map of skin dose from these detectors and measures the effects of in vivo dosimeters used for radiotherapy dose assessment.
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Affiliation(s)
- Hani Alnawaf
- Centre for Medical Radiation Physics, Illawarra Health and Medical Research Institute, University of Wollongong, Northfields Ave, Gwynneville, NSW, Australia
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Practical considerations for reporting surface dose in external beam radiotherapy: a 6 MV X-ray beam study. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2012; 35:271-82. [DOI: 10.1007/s13246-012-0145-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Accepted: 05/28/2012] [Indexed: 11/25/2022]
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Walters J, Ryan S, Harmon JF. Characterization of differences in calculated and actual measured skin doses to canine limbs during stereotactic radiosurgery using Gafchromic film. Med Dosim 2012; 37:201-7. [DOI: 10.1016/j.meddos.2011.07.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 07/01/2011] [Accepted: 07/21/2011] [Indexed: 11/30/2022]
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Chakarova R, Gustafsson M, Bäck A, Drugge N, Palm Å, Lindberg A, Berglund M. Superficial dose distribution in breast for tangential radiation treatment, Monte Carlo evaluation of Eclipse algorithms in case of phantom and patient geometries. Radiother Oncol 2012; 102:102-7. [DOI: 10.1016/j.radonc.2011.06.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 06/08/2011] [Accepted: 06/12/2011] [Indexed: 10/18/2022]
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Jin H, Hsi W, Yeung D, Li Z, Mendenhall NP, Marcus RB. Dosimetric characterization of whole brain radiotherapy of pediatric patients using modulated proton beams. J Appl Clin Med Phys 2011; 12:3308. [PMID: 21587172 PMCID: PMC5718672 DOI: 10.1120/jacmp.v12i2.3308] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Revised: 12/02/2010] [Accepted: 11/29/2010] [Indexed: 12/11/2022] Open
Abstract
This study was designed to investigate dosimetric variations between proton plans with (PPW) and without (PPWO), a compensator for whole brain radiotherapy (WBRT). The retrospective study on PPW and PPWO in Eclipse and XiO systems and photon plans (XP) using controlled segments in Pinnacle system was performed on nine pediatric patients for craniospinal irradiations. DVHs and derived metrics, such as the homogeneity index (HI), the doses to 2%(D2%) and 5%(D5%) volumes, and mean dose (Dmean) of the whole brain (i.e., PTV), and the organs at risk (OARs) such as lens and skull, were obtained. The PPW plans from both Eclipse and XiO systems uncovered the following advantages: (1) encompassing a cribriform plate area with the 100% isodose line was better than either PPWO or XP, according to calculated two‐dimensional distributions of one patient; (2) the mean value of D5% for lens was reduced to 23.6% of DP from 54.1% for PPWO or 41.6% for XP; and (3) the mean value of Dmean for skull was reduced to 94.8% of DP from either 98.4% for PPWO or 98.3% for XP. However, the PPW plans also exposed several disadvantages including: (1) the HI of PTV increased to 7.7 from 4.7 for PPWO or 3.7 for XP; (2) D2% to PTV increased to 108.8% of DP from 104.8% for PPWO or 105.1% for XP; and (3) D5% to the skull increased to 104.9% of DP from 101.6% for PPWO or 103.4% of for XP. One‐half of the observed variations were caused by different penumbra on lateral profiles and distal fall‐off depth doses of protons in Eclipse and XiO. Because the utilization on the sharp proton distal fall‐off was limited for WBRT, the difference between PPW and PPWO or XP indicated no distinguishable improvement by using a compensator in proton plans. PACS number: 87.55.‐x
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Affiliation(s)
- Hosang Jin
- University of Florida Proton Therapy Institute, Jacksonville, Florida 32206, USA.
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Chow JCL, Jiang R, Leung MKK. Dosimetry of oblique tangential photon beams calculated by superposition/convolution algorithms: a Monte Carlo evaluation. J Appl Clin Med Phys 2010; 12:3424. [PMID: 21330989 PMCID: PMC5718594 DOI: 10.1120/jacmp.v12i1.3424] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 09/14/2010] [Accepted: 09/24/2010] [Indexed: 11/23/2022] Open
Abstract
Although there are many works on evaluating dose calculations of the anisotropic analytical algorithm (AAA) using various homogeneous and heterogeneous phantoms, related work concerning dosimetry due to tangential photon beam is lacking. In this study, dosimetry predicted by the AAA and collapsed cone convolution (CCC) algorithm was evaluated using the tangential photon beam and phantom geometry. The photon beams of 6 and 15 MV with field sizes of 4 × 4 (or 7 × 7), 10 × 10 and 20 × 20 cm², produced by a Varian 21 EX linear accelerator, were used to test performances of the AAA and CCC using Monte Carlo (MC) simulation (EGSnrc-based code) as a benchmark. Horizontal dose profiles at different depths, phantom skin profiles (i.e., vertical dose profiles at a distance of 2 mm from the phantom lateral surface), gamma dose distributions, and dose-volume histograms (DVHs) of skin slab were determined. For dose profiles at different depths, the CCC agreed better with doses in the air-phantom region, while both the AAA and CCC agreed well with doses in the penumbra region, when compared to the MC. Gamma evaluations between the AAA/CCC and MC showed that deviations of 2D dose distribution occurred in both beam edges in the phantom and air-phantom interface. Moreover, the gamma dose deviation is less significant in the air-phantom interface than the penumbra. DVHs of skin slab showed that both the AAA and CCC underestimated the width of the dose drop-off region for both the 6 and 15 MV photon beams. When the gantry angle was 0°, it was found that both the AAA and CCC overestimated doses in the phantom skin profiles compared to the MC, with various photon beam energies and field sizes. The mean dose differences with doses normalized to the prescription point for the AAA and CCC were respectively: 7.6% ± 2.6% and 2.1% ± 1.3% for a 10 × 10 cm2 field, 6 MV; 16.3%± 2.1% and 6.7% ± 2.1% for a 20 × 20 cm2 field, 6 MV; 5.5% ± 1.2% and 1.7% ± 1.4% for a 10 × 10 cm2, 15 MV; 18.0% ± 1.3% and 8.3% ± 1.8% for a 20 × 20 cm², 15 MV. However, underestimations of doses in the phantom skin profile were found with small fields of 4 × 4 and 7 × 7 cm² for the 6 and 15 MV photon beams, respectively, when the gantry was turned 5° anticlockwise. As surface dose with tangential photon beam geometry is important in some radiation treatment sites such as breast, chest wall and sarcoma, it is found that neither of the treatment planning system algorithms can predict the dose well at depths shallower than 2 mm. The dosimetry data and beam and phantom geometry in this study provide a better knowledge of a dose calculation algorithm in tangential-like irradiation.
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Affiliation(s)
- James C L Chow
- Department of Radiation Oncology, University of Toronto and Radiation Medicine Program, Toronto, ON, Canada.
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Skin dose study of chest wall treatment with tomotherapy. Jpn J Radiol 2009; 27:355-62. [DOI: 10.1007/s11604-009-0357-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Accepted: 07/30/2009] [Indexed: 11/26/2022]
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Panettieri V, Barsoum P, Westermark M, Brualla L, Lax I. AAA and PBC calculation accuracy in the surface build-up region in tangential beam treatments. Phantom and breast case study with the Monte Carlo code penelope. Radiother Oncol 2009; 93:94-101. [DOI: 10.1016/j.radonc.2009.05.010] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Revised: 05/05/2009] [Accepted: 05/10/2009] [Indexed: 11/30/2022]
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Costa AM, Barbi GL, Bertucci EC, Ferreira H, Sansavino SZ, Colenci B, Caldas LVE. In vivo dosimetry with thermoluminescent dosimeters in external photon beam radiotherapy. Appl Radiat Isot 2009; 68:760-2. [PMID: 19819151 DOI: 10.1016/j.apradiso.2009.09.039] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The ultimate check of the actual dose delivered to a patient in radiotherapy can only be achieved by using in vivo dosimetry. This work reports a pilot study to test the applicability of a thermoluminescent dosimetric system for performing in vivo entrance dose measurements in external photon beam radiotherapy. The measurements demonstrated the value of thermoluminescent dosimetry as a treatment verification method and its applicability as a part of a quality assurance program in radiotherapy.
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Affiliation(s)
- Alessandro M Costa
- Departamento de Física e Matemática, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
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Hardcastle N, Soisson E, Metcalfe P, Rosenfeld AB, Tomé WA. Dosimetric verification of helical tomotherapy for total scalp irradiation. Med Phys 2008; 35:5061-8. [DOI: 10.1118/1.2996288] [Citation(s) in RCA: 31] [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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