방사선 치료 시 종양선량을 예측하는 방법에 관한 연구

• 영문명: A study on in-vivo dosimetry for radiation therapy
• 발행기관: 고려대학교 보건과학연구소
• 저자명: 최종학(JongHak Choi) 고현식(HyunSik Ko) 이병구(BungGu Lee) 김유현(YouHyun Kim)
• 간행물 정보: 『보건과학논집』保健科學論集 Vol.29 No.2, 31~36쪽, 전체 6쪽
• 주제분류: 의약학 > 의학일반
• 파일형태: PDF
• 발행일자: 2003.12.01

영문 초록

  The aim of this study is to develop a simple method which computes in-vivo doses from transmission doses measured during patient treatment using an ionization chamber.
  Energy fluence and the dose that reach the chamber positioned behind the patient is modified by three factors : patient attenuation, inverse square attenuation, and scattering. We adopted a straightforward empirical approach using a phantom transmission factor (PTF) which accounts for the contribution from all three factors. It was done as follows.
  First of all, the phantom transmission factor was measured as a simple ratio of the chamber reading measured with and without a homogeneous phantom in the radiation beam according to various field sizes(r<SUB>p</SUB>) and phantom thickness(T<SUB>p</SUB>).
  Secondly, we used the concept of effective field to the cases with irregular fields. The effective field size is calculated by finding the field size that produces the same value of PTF to that for the irregular field. The hypothesis is that the presence of irregular field can be accommodated to a certain extent by altering the field size. Thirdly, the center dose at the prescription depth can be computed using the new TMR(r<SUB>p,eff</SUB>) and Sp(r<SUB>p,eff</SUB>) from the effective field size. After that, when TMR(d, r<SUB>p,eff</SUB>) and Sp(r<SUB>p,eff</SUB>) are acquired, the tumor dose is as follows.
  D<SUB>center</SUB> = D<SUB>t</SUB>/PTF(d<SUB>g</SUB>, T<SUB>p</SUB>) × ( SCD/SAD)² × S<SUB>p</SUB>(r<SUB>p,eff</SUB>) × TMR(d, r<SUB>p,eff</SUB>)
  As the field size increased, the errors showed a tendency to increase. Generally, with this method the absolute midline dose was predicted with an accuracy of about 2.53% and 2.37% for 6 ㎹ and 10MV X-rays.
  A simple method of in-vivo dose reconstruction and verification was developed. The efficacy of this method is limited by the field size. Thus, the method developed in this study should be used with care for relatively large field sizes. Further clinical test awaits this study.

목차

Abstract
Ⅰ. 서론
Ⅱ. 재료 및 방법
Ⅲ. 결과 및 고찰
Ⅳ. 결론
참고문헌