This
study describes the development of a simple method to assess inter-fractional
deviations of delivered proton beams in treatment rooms. To monitor the
treatment beam, we measured the field-by-field beam fluences by attaching the
EBT3 film to the snout, followed by a simple constancy check based on
comparisons between the reference beam fluences (acquired during the
pre-treatment quality assurance process) and the test beam fluences (acquired
during treatment). The feasibility of the proposed treatment beam-monitoring
system was confirmed by evaluating 12 treatment fields for each of six patients
(brain, liver, prostate, lung, cranial and spinal area, and head and neck). The
constancy of the treatment beams was verified by using a gamma index analysis to
compare three measurements per field with the reference beam fluence. On the
basis of the 3%/3 mm criterion, the average gamma-index passing rates for all
measurements were over 99.6%. These results suggest that the constancy of
fractional proton beams delivered to patients in treatment rooms can be
verified with EBT3 film-based proton-beam monitoring system that can be easily
attached to the treatment nozzle and is cost effective.
Seonghoon Jeong
Proton Therapy Center, National Cancer
Center, Goyang Korea
Myonggeun Yoon∗
Department of Bio-convergence Engineering,
Korea University, Seoul, Korea
Kwangzoo Chung†
Department of Radiation Oncology, Samsung Medical
Center, School of Medicine, Sungkyunkwan University, Seoul, Korea
Journal of the Korean Physical
Society, Vol. 76, No. 8, April 2020, pp. 769∼773