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Shiau AC, Hsu SM, Huang PY, Chen CP, Huang YT, Lien KY, Chen CP, Fan SH, Jeng SC, Chen HH, Liang JA. Dosimetry audits in Taiwan radiotherapy departments. BJR Open 2021; 3:20210002. [PMID: 35707755 PMCID: PMC9185846 DOI: 10.1259/bjro.20210002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 03/12/2021] [Accepted: 03/16/2021] [Indexed: 11/05/2022] Open
Abstract
Objectives: This study examines the practice of the regulation of Standards for Medical Exposure Quality Assurance (SMEQA) in Taiwan based on on-site quality audit for radiation therapy systems from 2016 to 2019. Methods: 81 radiation therapy departments, 141 linacs, 9 γ knife systems, 34 high dose rate brachytherapy systems, 20 Tomotherapys, and 6 Cyberknives were audited yearly. Data collection and analysis for each institute’s documents including QA procedure, ion chamber and electrometer calibration reports, and a questionnaire relating to machine type and staffing, were requested first and reviewed by auditors. On-site SMEQA core item measurements, including beam output, beam profile and energy constancy for external beam therapy systems, and the source strength, positioning, and timer accuracy for brachytherapy systems were audited second. More than 300 photon beams and more than 400 electron beams were measured each year. Results: There were approximately 8.9 radiotherapy units per million population, and 1.2 medical physicists per unit in Taiwan. For the output measurements, more than 78 and 75% of the photon beams and electron beams, respectively, from linacs were with deviations within ±1.0%. Photon beams have lower beam quality measurement deviations than electron beams. Including in-plane and cross-plane measurements, more than 90 and 85% photon and electron beams, respectively, were with flatness consistency within 1.0%. All audit measurements were within the SMEQA acceptance criteria. Conclusions: According to SMEQA regulations on-site QA audits were successfully carried out from 2016 to 2019 for all Taiwan radiotherapy units. The measurement results showed high quality machine performance in Taiwan. Advances in knowledge: Dosimetry audits with directly acquired measurement readings have lower uncertainties; allow immediate feedback, discussion, and adjustment in a timely manner. In addition to regulation system establishment and education and training implementation, the machine quality is closely related to machine maintenance implementation.
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Affiliation(s)
- An-Cheng Shiau
- Department of Radiation Oncology, China Medical University Hospital, Taichung, Taiwan
- Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan
- Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, Taiwan
| | - Shih-Ming Hsu
- Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Pei-Yun Huang
- Department of Radiation Oncology, Taoyuan Armed Forces General Hospital, Taoyuan, Taiwan
| | - Chiu-Ping Chen
- Department of Radiation Oncology, Taipei Medical University-associated Wan-Fang Hospital, Taipei, Taiwan
| | - Yi-Ting Huang
- Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Ke-Yu Lien
- Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Chin-Ping Chen
- Department of Radiation Protection, Atomic Energy Council, Taipei, Taiwan
| | - Shung-Hwei Fan
- Department of Radiation Protection, Atomic Energy Council, Taipei, Taiwan
| | - Shiu-Chen Jeng
- Department of Radiation Oncology, Taipei Medical University Hospital, Taipei, Taiwan
| | - Ho-Hsing Chen
- Department of Radiation Oncology, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Ji-An Liang
- Department of Radiation Oncology, China Medical University Hospital, Taichung, Taiwan
- Department of Medicine, China Medical University, Taichung, Taiwan
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Ade N, du Plessis FCP. Dose comparison between Gafchromic film, XiO, and Monaco treatment planning systems in a novel pelvic phantom that contains a titanium hip prosthesis. J Appl Clin Med Phys 2017; 18:162-173. [PMID: 28741892 PMCID: PMC5874810 DOI: 10.1002/acm2.12141] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 06/05/2017] [Accepted: 06/09/2017] [Indexed: 11/29/2022] Open
Abstract
The presence of metallic prostheses during external beam radiotherapy of malignancies in the pelvic region has the potential to strongly influence the dose distribution to the target and to tissue surrounded by the prostheses. This study systematically investigates the perturbation effects of unilateral titanium prosthesis on 6 and 15 MV photon beam dose distributions using Gafchromic EBT2 film measurements in a novel pelvic phantom made out of a stack of nylon slices. Comparisons were also made between the film data and dose calculations made on XiO and Monaco treatment planning systems. The collapsed cone algorithm was chosen for the XiO and the Monte Carlo algorithm used on Monaco is XVMC. Transmission measurements were taken using a narrow‐beam geometry to determine the mass attenuation coefficient of nylon = 0.0458 cm2/g and for a water‐equivalent RW3 phantom, it was 0.0465 cm2/g. The perturbation effects of the prosthesis on dose distributions were investigated by measuring and comparing dose maps and profiles. The magnitude of dose perturbations was quantified by calculating dose enhancement and reduction factors using field sizes of 3 × 3, 5 × 5, 10 × 10, and 15 × 15 cm2. For the studied beams and field sizes, dose enhancements between 21 and 30% and dose reductions between 15 and 21% were observed at the nylon‐prosthesis interface on the proximal and distal sides of the prosthesis for film measurements. The dose escalation increases with beam energy, and the dose reduction due to attenuation decreases with increasing beam energy when compared to unattenuated beam data. A comparison of film and XiO depth doses for the studied fields gave relative errors between 1.1 and 23.2% at the proximal and distal interfaces of the Ti prosthesis. Also, relative errors < 4.0% were obtained between film and Monaco dose data outside the prosthesis for 6 and 15 MV lateral opposing fields.
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Affiliation(s)
- Nicholas Ade
- Medical Physics Department, University of the Free State, Bloemfontein, South Africa
| | - F C P du Plessis
- Medical Physics Department, University of the Free State, Bloemfontein, South Africa
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Charles PH, Crowe SB, Kairn T, Kenny J, Lehmann J, Lye J, Dunn L, Hill B, Knight RT, Langton CM, Trapp JV. The effect of very small air gaps on small field dosimetry. Phys Med Biol 2012; 57:6947-60. [DOI: 10.1088/0031-9155/57/21/6947] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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