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Madden L, Roberts N, Jelen U, Dong B, Holloway L, Metcalfe P, Rosenfeld A, Li E. In-line MRI-LINAC depth dose measurements using an in-house plastic scintillation dosimeter. Biomed Phys Eng Express 2021; 7. [PMID: 33530066 DOI: 10.1088/2057-1976/abe295] [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: 10/08/2020] [Accepted: 02/02/2021] [Indexed: 11/12/2022]
Abstract
Plastic scintillation dosimeters (PSDs) have many properties that make them desirable for relative dosimetry with MRI-LINACs. An in-house PSD, Farmer ionisation chamber and Gafchromic EBT3 film were used to measure central axis percentage depth dose distributions (PDDs) at the Australian MRI-LINAC Mean errors were calculated between each detector's responses, where the in-house PSD was on average within 0.7% of the Farmer chamber and 1.4% of film, while the Farmer chamber and film were on average within 1.1% of each other. However, the PSD systematically over-estimated the dose as depth increased, approaching a maximum overestimation of the order of 3.5% for the smallest field size measured. This trend was statistically insignificant for all other field sizes measured; further investigation is required to determine the source of this effect. The calculated values of mean absolute error are comparable to the those of trusted dosimeters reported in the literature. These mean absolute errors, and the ubiquity of desirable dosimetric qualities inherent to PSDs suggest that PSDs in general are accurate for relative dosimetry with the MRI-LINAC. Further investigation is required into the source of the reported systematic trends dependent on field-size and depth of measurement.
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Affiliation(s)
- Levi Madden
- Centre for Medical Radiation Physics, University of Wollongong, NSW 2522, Australia.,Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia
| | - Natalia Roberts
- Centre for Medical Radiation Physics, University of Wollongong, NSW 2522, Australia.,Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia
| | - Urszula Jelen
- GenesisCare St Vincent's Clinic, Darlinghurst, NSW 2010, Australia
| | - Bin Dong
- Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia
| | - Lois Holloway
- Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia.,Liverpool Cancer Therapy Centre, Liverpool, NSW 2170, Australia.,Macauthur Cancer Therapy Clinic, Campbelltown, NSW 2560, Australia
| | - Peter Metcalfe
- Centre for Medical Radiation Physics, University of Wollongong, NSW 2522, Australia.,Illawarra Medical and Health Research Institute, University of Wollongong, NSW 2522, Australia
| | - Anatoly Rosenfeld
- Centre for Medical Radiation Physics, University of Wollongong, NSW 2522, Australia.,Illawarra Medical and Health Research Institute, University of Wollongong, NSW 2522, Australia
| | - Enbang Li
- Centre for Medical Radiation Physics, University of Wollongong, NSW 2522, Australia
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