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Lin C, Tsai Y, Chen L, Wang C, Wu C, Chen W, Liang H, Kuo S. Effect of extended field-of-view approaches on the accuracy of stopping power ratio estimation for single-energy computed tomography simulators. J Appl Clin Med Phys 2023; 24:e14010. [PMID: 37170691 PMCID: PMC10476990 DOI: 10.1002/acm2.14010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 04/06/2023] [Accepted: 04/10/2023] [Indexed: 05/13/2023] Open
Abstract
BACKGROUND Extended field-of-view (eFOV) methods have been proposed to generate larger demonstration FOVs for computed tomography (CT) simulators with a limited scanning FOV (sFOV) size in order to ensure accurate dose calculation and patient collision avoidance. Although the efficacy of these strategies has been evaluated for photon applications, the effect of stopping power ratio (SPR) estimation on proton therapy has not been studied. This study investigated the effect of an eFOV approach on the accuracy of SPR to water estimation in homogeneous and heterogeneous phantoms. MATERIALS AND METHODS To simulate patient geometries, tissue-equivalent material (TEM) and customized extension phantoms were used. The TEM phantom supported various rod arrangements through predefined holes. Images were reconstructed to three FOV sizes using a commercial eFOV technique. A single-energy CT stoichiometric method was used to generate Hounsfield unit (HU) to SPR (HU-to-SPR) conversion curves for each FOV. To investigate the effect of rod location in the sFOV and eFOV regions, eight TEM rods were placed at off-center distances in the homogeneous phantom and scanned individually. Similarly, 16 TEM rods were placed in the heterogeneous TEM phantom and scanned simultaneously. RESULTS The conversion curves derived from the sFOV and eFOV data were identical. The average SPR differences of soft-tissue, bone, and lung materials for rods placed at various off-center locations were 3.3%, 4.8%, and 39.6%, respectively. In the heterogeneous phantom, the difference was within 1.0% in the absence of extension. However, in the presence of extension, the difference increased to 2.8% for all rods, except for lung materials, whose difference was 4.8%. CONCLUSIONS When an eFOV method is used, the SPR variation in phantoms considerably increases for all TEM rods, especially for lung TEM rods. This phenomenon may substantially increase the uncertainty of HU-to-SPR conversion. Therefore, image reconstruction with a standard FOV size is recommended.
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Affiliation(s)
- Chang‐Shiun Lin
- Department of Radiation OncologyNational Taiwan University Cancer CenterTaipeiTaiwan
| | - Yi‐Chun Tsai
- Division of radiation oncologydepartment of OncologyNational Taiwan University HospitalTaipeiTaiwan
| | - Liang‐Hsin Chen
- Department of Radiation OncologyNational Taiwan University Cancer CenterTaipeiTaiwan
| | - Chun‐Wei Wang
- Division of radiation oncologydepartment of OncologyNational Taiwan University HospitalTaipeiTaiwan
| | - Chia‐Jung Wu
- Department of Radiation OncologyNational Taiwan University Cancer CenterTaipeiTaiwan
| | - Wan‐Yu Chen
- Department of Radiation OncologyNational Taiwan University Cancer CenterTaipeiTaiwan
| | - Hsiang‐Kung Liang
- Department of Radiation OncologyNational Taiwan University Cancer CenterTaipeiTaiwan
| | - Sung‐Hsin Kuo
- Department of Radiation OncologyNational Taiwan University Cancer CenterTaipeiTaiwan
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Grassi R, Guerra E, Berritto D. Bone fractures difficult to recognize in emergency: May be cone beam computed tomography (CBCT) the solution? LA RADIOLOGIA MEDICA 2023; 128:1-5. [PMID: 36683134 DOI: 10.1007/s11547-022-01584-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 12/20/2022] [Indexed: 01/23/2023]
Abstract
CBCT is an imaging tool represented by an X-ray computed tomography delivering a conic-shape X-rays source. This system produces volumetric data during a single rotation of both X-ray beam and detector around the stationary patient. CBCT is able to produce three-dimensional images as for MDCT, however, accounting some advantages over it: lower radiation dose, faster volumetric dataset acquisition, higher spatial resolution and bone contrast. For these reasons, CBCT has recently been described and adopted for extremities imaging in orthopedics. Misinterpretation of fractures may determine a delayed treatment and poor outcome for patients treated in the ED. CBCT, by easily identifying occult cortical fractures and using a lower dose of radiation, is proposed as an alternative or supplement to direct radiograms, optimizing the cost-effectiveness ratio and limiting the number of unnecessary immobilizations. The first experiences document excellent performance of CBCT in emergency radiology departments, especially thanks to transverse imaging in trauma of the extremities.
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Affiliation(s)
- Roberto Grassi
- Department of Precision Medicine, University of Campania Luigi Vanvitelli, Naples, Italy
| | - Egidio Guerra
- Division of Radiology, "Ospedale Policlinico di Foggia", Foggia, Italy
| | - Daniela Berritto
- Department of Clinical and Experimental Medicine, University of Foggia, Foggia, Italy.
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Hansen CR, Hussein M, Bernchou U, Zukauskaite R, Thwaites D. Plan quality in radiotherapy treatment planning - Review of the factors and challenges. J Med Imaging Radiat Oncol 2022; 66:267-278. [PMID: 35243775 DOI: 10.1111/1754-9485.13374] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 12/14/2021] [Indexed: 12/25/2022]
Abstract
A high-quality treatment plan aims to best achieve the clinical prescription, balancing high target dose to maximise tumour control against sufficiently low organ-at-risk dose for acceptably low toxicity. Treatment planning (TP) includes multiple steps from simulation/imaging and segmentation to technical plan production and reporting. Consistent quality across this process requires close collaboration and communication between clinical and technical experts, to clearly understand clinical requirements and priorities and also practical uncertainties, limitations and compromises. TP quality depends on many aspects, starting from commissioning and quality management of the treatment planning system (TPS), including its measured input data and detailed understanding of TPS models and limitations. It requires rigorous quality assurance of the whole planning process and it links to plan deliverability, assessable by measurement-based verification. This review highlights some factors influencing plan quality, for consideration for optimal plan construction and hence optimal outcomes for each patient. It also indicates some challenges, sources of difference and current developments. The topics considered include: the evolution of TP techniques; dose prescription issues; tools and methods to evaluate plan quality; and some aspects of practical TP. The understanding of what constitutes a high-quality treatment plan continues to evolve with new techniques, delivery methods and related evidence-based science. This review summarises the current position, noting developments in the concept and the need for further robust tools to help achieve it.
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Affiliation(s)
- Christian Rønn Hansen
- Laboratory of Radiation Physics, Odense University Hospital, Odense, Denmark.,Department of Clinical Research, University of Southern Denmark, Odense, Denmark.,Institute of Medical Physics, School of Physics, University of Sydney, Sydney, NSW, Australia.,Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | - Mohammad Hussein
- Metrology for Medical Physics Centre, National Physical Laboratory, Teddington, UK
| | - Uffe Bernchou
- Laboratory of Radiation Physics, Odense University Hospital, Odense, Denmark.,Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Ruta Zukauskaite
- Department of Clinical Research, University of Southern Denmark, Odense, Denmark.,Department of Oncology, Odense University Hospital, Odense, Denmark
| | - David Thwaites
- Institute of Medical Physics, School of Physics, University of Sydney, Sydney, NSW, Australia
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Optimisation of CT scan parameters to increase the accuracy of gross tumour volume identification in brain radiotherapy. JOURNAL OF RADIOTHERAPY IN PRACTICE 2021. [DOI: 10.1017/s1460396920000436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractAim:This study aimed to optimise computed tomography (CT) simulation scan parameters to increase the accuracy for gross tumour volume identification in brain radiotherapy. For this purpose, high-contrast scan protocols were assessed.Materials and methods:A CT accreditation phantom (ACR Gammex 464) was used to optimise brain CT scan parameters on a Toshiba Alexion 16-row multislice CT scanner. Dose, tube voltage, tube current–time and CT dose index (CTDI) were varied to create five image quality enhancement (IQE) protocols. They were assessed in terms of contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR) and noise level and compared with a standard clinical protocol. Finally, the ability of the selected protocols to identify low-contrast objects was examined based on a subjective method.Results:Among the five IQE protocols, the one with the highest tube current–time product (250 mA) and lowest tube voltage (100 kVp) showed higher CNR, while another with a tube current–time product of 150 mA and a tube voltage of 135 kVp had improved SNR and lower noise level compared to the standard protocol. In contouring low-contrast objects, the protocol with the highest milliampere and lowest peak kilovoltage exhibited the lowest error rate (1%) compared to the standard protocol (25%).Findings:CT image quality should be optimised using the high-dose parameters created in this study to provide better soft tissue contrast. This could lead to an accurate identification of gross tumour volume recognition in the planning of radiotherapy treatment.
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Spronk D, Luo Y, Inscoe CR, Lee YZ, Lu J, Zhou O. Evaluation of carbon nanotube x-ray source array for stationary head computed tomography. Med Phys 2021; 48:1089-1099. [PMID: 33382470 DOI: 10.1002/mp.14696] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 11/30/2020] [Accepted: 12/02/2020] [Indexed: 01/12/2023] Open
Abstract
PURPOSE Stationary computed tomography (s-CT) conceptually offers several advantages over existing rotating gantry-based CT. Over the last 40 yr, s-CT has been investigated using different technological approaches. We are developing a s-CT system specifically for head/brain imaging using carbon nanotube (CNT)-based field emission x-ray source array technology. The noncircular geometry requires different assessment approaches as compared to circular geometries. The purpose of the present study is to investigate whether the CNT source array meets the requirements for stationary head CT (s-HCT). METHODS Multiple prototype CNT x-ray source arrays were manufactured based on the system requirements obtained from simulation. Source characterization was performed using a benchtop setup consisting of an x-ray source array with 45 distributed focal spots, each operating at 120 kVp, and an electronic control system (ECS) for high speed control of the x-ray output from individual focal spots. Due to the forward-angled geometry of the linear anode, the projected focal spot shape is expected to vary at wide angle views. A pinhole method was implemented to determine the effective focal spot size (FSS) in the imaging plane at a range of angular viewpoints with a flat panel detector. The output spectrum and half value layer (HVL) were also evaluated for a range of viewing angles to characterize the beam quality across the fan-beam. Dosimetry was performed on a simulated scan to evaluate total exposure. RESULTS The prototype CNT x-ray source array demonstrated adequate specifications for a s-HCT imaging machine. The source array was operated at 120 kVp with long-term stability over a full year of regular laboratory use. Multiple cathode current measurements were used to confirm submicrosecond accuracy with regards to exposure time and subsequently dose control. All 45 focal spots were measured with an average value of 1.26 (±0.04) mm × 1.21 (±0.03) mm (equivalent to IEC 1,0). The x-ray spectrum was found to be appropriately filtered based on sources used in existing rotary CT systems. A stable and reliable output of 0.04 mAs per emitter and a resulting dose of 0.015 mGy per projection were observed over several months of rigorous phantom imaging. Dose per projection was regulated by the ECS and measured with ±0.5% tolerance. CONCLUSIONS The CNT x-ray source array was found to meet the requirements for the proposed stationary head CT scanner, with regard to FSS, beam quality, and dose precision. The remaining challenges are related to the overall system design of a nonrotating CT scanner with distributed sources. The next phase of the project will incorporate multiple CNT source arrays with multirow detectors in a proof-of-concept study and analysis of a fully functional s-HCT system.
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Affiliation(s)
- Derrek Spronk
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Yueting Luo
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Christina R Inscoe
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Yueh Z Lee
- Department of Radiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Jianping Lu
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Otto Zhou
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
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Zalokar N, Žager Marciuš V, Mekiš N. Establishment of national diagnostic reference levels for radiotherapy computed tomography simulation procedures in Slovenia. Eur J Radiol 2020; 127:108979. [PMID: 32302897 DOI: 10.1016/j.ejrad.2020.108979] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 02/25/2020] [Accepted: 03/25/2020] [Indexed: 11/28/2022]
Abstract
PURPOSE To propose national diagnostic reference levels (DRLs) for radiotherapy (RT) computed tomography (CT) localization purposes, compare both CT units used in the largest RT department in the country and to compare gathered results with other published DRLs in order to discover any need of optimization. METHODS In total, 1631 patient data (time spend of 4 months) regarding sex, examination type, total dose-length product (DLP) and CTDIvol was collated on two CT units. Those simulation procedures account for more than 80 % of all simulation procedures performed nationwide. Then, total DLP and CTDIvol was calculated and mean, median and 3rd quartile for both units together were presented to determine national DRLs for simulation procedures. The same data was later compared between both units to discover any potential need for optimization. RESULTS 3rd quartile values of DLP for abdomen, breast, chest, head, head and neck, pelvis and spine were 1116.2, 606.6, 832.4, 1942.4, 969.2, 677.1 and 1042.4 mGy∙cm, respectively. 3rd quartile CTDIvol values for the same sequence of procedures were 18.7, 13.3, 19.2, 76.9, 22.6, 17.9 and 22.2 mGy, respectively. Among the two units, the mentioned dose values were on average significantly higher on one CT unit than on the other unit. CONCLUSIONS When comparing collected dose values with other studies, RT CT DRLs showed that radiation doses from our institution were similar or even lower. Some variations were found between both CT units in certain protocols, so exposure parameters should be reviewed and optimized.
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Affiliation(s)
- Nika Zalokar
- University of Ljubljana, Faculty of Health Sciences, Medical Imaging and Radiotherapy Department, Zdravstvena pot 5, 1000, Ljubljana, Slovenia
| | - Valerija Žager Marciuš
- University of Ljubljana, Faculty of Health Sciences, Medical Imaging and Radiotherapy Department, Zdravstvena pot 5, 1000, Ljubljana, Slovenia; Institute of Oncology Ljubljana, Teleradiotherapy Department, Zaloška cesta 2, 1000 Ljubljana, Slovenia
| | - Nejc Mekiš
- University of Ljubljana, Faculty of Health Sciences, Medical Imaging and Radiotherapy Department, Zdravstvena pot 5, 1000, Ljubljana, Slovenia.
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Wu RY, Williamson TD, Sahoo N, Nguyen T, Ikner SM, Liu AY, Wisdom PG, Lii M, Hunter RA, Alvarez PE, Gunn GB, Frank SJ, Hojo Y, Zhu XR, Gillin MT. Evaluation of the high definition field of view option of a large-bore computed tomography scanner for radiation therapy simulation. Phys Imaging Radiat Oncol 2020; 13:44-49. [PMID: 32551371 PMCID: PMC7302052 DOI: 10.1016/j.phro.2020.03.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Background and purpose Computed tomography (CT) scanning is the basis for radiation treatment planning, but the 50-cm standard scanning field of view (sFOV) may be too small for imaging larger patients. We evaluated the 65-cm high-definition (HD) FOV of a large-bore CT scanner for CT number accuracy, geometric distortion, image quality degradation, and dosimetric accuracy of photon treatment plans. Materials and methods CT number accuracy was tested by placing two 16-cm acrylic phantoms on either side of a 40-cm phantom to simulate a large patient extending beyond the 50-cm-diameter standard scanning FOV. Dosimetric accuracy was tested using anthropomorphic pelvis and thorax phantoms, with additional acrylic body parts on either side of the phantoms. Two volumetric modulated arc therapy beams (a 15-MV and a 6-MV) were used to cover the planning target volumes. Two-dimensional dose distributions were evaluated with GAFChromic film and point dose accuracy was checked with multiple thermoluminescent dosimeter (TLD) capsules placed in the phantoms. Image quality was tested by placing an American College of Radiology accreditation phantom inside the 40-cm phantom. Results The HD FOV showed substantial changes in CT numbers, with differences of 314 HU–725 HU at different density levels. The volume of the body parts extending into the HD FOV was distorted. However, TLD-reported doses for all PTVs agreed within ±3%. Dose agreement in organs at risk were within the passing criteria, and the gamma index pass rate was >97%. Image quality was degraded. Conclusions The HD FOV option is adequate for RT simulation and met accreditation standards, although care should be taken during contouring because of reduced image quality.
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Affiliation(s)
- Richard Y. Wu
- Departments of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
- Corresponding author at: Department of Radiation Physics, Box 94, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, United States.
| | - Tyler D. Williamson
- Departments of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Narayan Sahoo
- Departments of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Trang Nguyen
- Departments of Imaging and Radiation Oncology Core, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Shane M. Ikner
- Departments of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Amy Y. Liu
- Departments of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Paul G. Wisdom
- Departments of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - MingFu Lii
- Departments of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Rachel A. Hunter
- Departments of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Paola E. Alvarez
- Departments of Imaging and Radiation Oncology Core, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - G. Brandon Gunn
- Departments of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Steven J. Frank
- Departments of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Yoshifumi Hojo
- Departments of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - X. Ronald Zhu
- Departments of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Michael T. Gillin
- Departments of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
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Ota S. [16. Commissioning of a Computed Tomography Simulator: A Single-institution Experience]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2020; 76:413-422. [PMID: 32307369 DOI: 10.6009/jjrt.2020_jsrt_76.4.413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Affiliation(s)
- Seiichi Ota
- Radiotherapy Unit, Division of Radiological Technology, University Hospital, Kyoto Prefectural University of Medicine
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Rezaee M, Letourneau D. Assessment of Image Quality and Dosimetric Performance of CT Simulators. J Med Imaging Radiat Sci 2019; 50:297-307. [PMID: 31176438 DOI: 10.1016/j.jmir.2019.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 01/09/2019] [Accepted: 01/17/2019] [Indexed: 11/18/2022]
Abstract
BACKGROUND CT simulator for radiation therapy aims to produce high-quality images for dose calculation and delineation of target and organs at risk in the process of treatment planning. Selection of CT imaging protocols that achieve a desired image quality while minimizing patient dose depends on technical CT parameters and their relationship with image quality and radiation dose. For similar imaging protocols using comparable technical CT parameters, there are also variations in image quality metrics between different CT simulator models. Understanding the relationship and variation is important for selecting appropriate imaging protocol and standardizing QC process. Here, we proposed an automated method to determine the relationship between image quality and radiation dose for various CT technical parameters. MATERIAL AND METHOD The impact of scan parameters on various aspects of image quality and volumetric CT dose index for a Philips Brilliance Big Bore and a Toshiba Aquilion One CT scanners were determined by using commercial phantom and automated image quality analysis software and cylindrical radiation dose phantom. RESULTS AND DISCUSSION Both scanners had very similar and satisfactory performance based on the diagnostic acceptance criteria recommended by ACR, International Atomic Energy Agency, and American Association of Physicists in Medicine. However, our results showed a compromise between different image quality components such as low-contrast and spatial resolution with the change of scanning parameters and revealed variations between the two scanners on their image quality performance. Measurement using a generic phantom and analysis by automated software was unbiased and efficient. CONCLUSION This method provides information that can be used as a baseline for CT scanner image quality and dosimetric QC for different CT scanner models in a given institution or across sites.
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Affiliation(s)
- Mohammad Rezaee
- Department of Medical Physics, Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Canada.
| | - Daniel Letourneau
- Department of Medical Physics, Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Canada; Department of Radiation Oncology, Faculty of Medicine, University of Toronto, Toronto, Canada
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