Evaluation of International Atomic Energy Agency Technical Report Series-483 Detector-specific Output Correction Factor for Various Collimator Systems.

Autor: Kannan M; Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India., Saminathan S; Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India., Chandraraj V; Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India., Raj DG; Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India., Ganesh KM; Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India.
Jazyk: angličtina
Zdroj: Journal of medical physics [J Med Phys] 2023 Jul-Sep; Vol. 48 (3), pp. 281-288. Date of Electronic Publication: 2023 Sep 18.
DOI: 10.4103/jmp.jmp_59_23
Abstrakt: Aim: In this study, a 6MV flattening filter (FF) and 6MV FF Free (FFF) photon beam small-field output factors (OF) were measured with various collimators using different detectors. The corrected OFs were compared with the treatment planning system (TPS) calculated OFs.
Materials and Methods: OF measurements were performed with four different types of collimators: Varian Millennium multi-leaf collimator (MLC), Elekta Agility MLC, Apex micro-MLC (mMLC) and a stereotactic cone. Ten detectors (four ionization chambers and six diodes) were used to perform the OF measurements at a depth of 10 cm with a source-to-surface distance of 90 cm. The corrected OF was calculated from the measurements. The corrected OFs were compared with existing TPS-generated OFs.
Results: The use of detector-specific output correction factor (OCF) in the PTW diode P detector reduced the OF uncertainty by <4.1% for 1 cm × 1 cm S clin . The corrected OF was compared with TPS calculated OF; the maximum variation with the IBA CC01 chamber was 3.75%, 3.72%, 1.16%, and 0.90% for 5 mm stereotactic cone, 0.49 cm × 0.49 cm Apex mMLC, 1 cm × 1 cm Agility MLC, and 1 cm × 1 cm Millennium MLC, respectively.
Conclusion: The technical report series-483 protocol recommends that detector-specific OCF should be used to calculate the corrected OF from the measured OF. The implementation of OCF in the TPS commissioning will reduce the small-field OF variation by <3% for any type of detector.
Competing Interests: There are no conflicts of interest.
(Copyright: © 2023 Journal of Medical Physics.)
Databáze: MEDLINE
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