Development of the Algorithm for On-line Dosimetry System for High Energy Radiation Treatment

고에너지 방사선치료용 on-line 선량측정시스템을 위한 알고리즘의 개발

  • Wu, Hong-Hyun (Department Therapeutic Radiology, Seoul National University College Medicine) ;
  • Ha, Sung-Whan (Department Therapeutic Radiology, Seoul National University College Medicine)
  • 우홍균 (서울대학교 의과대학 치료방사선과학교실) ;
  • 하성환 (서울대학교 의과대학 치료방사선과학교실)
  • Published : 1997.09.30

Abstract

Purpose: The objective of this study is to develop an algorithm for estimation of tumor dose using measured transmission dose as a part of the development of on-line dosimetry system. Materials and Methods: Data of transmission dose were measured under various FS, Tp and PCD with a special water phantom for 6 MV and 10 MV X-ray. SCD (source-chamber distance) was set to 150 cm. Measurements were conducted with a 0.125 cc ion chamber. Results: Using measured data and regression analysis, two algorithms were developed for estimation of expected reading for measured data. Algorithm 1 consisted of the quadratic function of PCD and the tertiary function of AlP (area-perimeter ratio). Algorithm 2 consisted of the tertiary function of log(A/P)and the tertiary function of PCD. Algorithm 2 required less data set and was more accurate in comparing expected and observed dose. Conclusion: Using the algorithm developed, transmission dose can be estimated for any exposure condition, i.e. any given Tp, PCD and FS with high accuracy. To complete this algorithm, further developments are needed regarding the beam modifying device, the tissue inhomogeneity and the irregular body surface.