Journal of the Korean Society of Radiology (한국방사선학회논문지)

The Korean Society of Radiology (한국방사선학회)
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Evaluation of Absorbed Dose according to the Use of Bolus in Opposite Breast during Radiation Therapy of Breast Cancer using VMAT

VMAT를 이용한 유방암 방사선치료 시 반대편 유방의 Bolus 사용에 따른 흡수선량 평가

  • Kim, Jong-Bo (Department of Radiation Oncology, Dongnam Ins. of Radiological & Medical Science) ;
  • Shin, Sang-Hwa (Department of Radiological Science, Catholic University of Pusan)
  • 김종보 (동남권원자력의학원 방사선종양학과) ;
  • 신상화 (부산가톨릭대학교 방사선학과)
  • Received : 2018.10.25
  • Accepted : 20181131
  • Published : 2018.11.30
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Abstract

Although the development of radiation therapy techniques has made the treatment more precise, exposure by radiation is unavoidable beyond the treatment site. In this study, we wanted to evaluate the absorbed dose according to the thickness of the bolus on the opposite side of the treatment in radiation treatment for breast cancer and to analyze the effect of dose reduction. An experiment was conducted on Rando phantom using VMAT treatment methods. Five points of A, B, C, D, and E were selected for the breast opposite the treatment, and when the dosimeters of 5, 10, 15, and 20 mm were used. The highest absorbed dose at point D closest to the treatment point was measured and lowest at point B furthest from the treatment point. The mean absorbed dose was 8.61 cGy When the bolus is not used and 8.10, 7.94, 8.06, and 8.10 cGy Depending on the thickness of the bolus. In this study, bolus was intended to be used to analyze the dose-reducing effects of breasts on the other side of the treatment. The results of the study showed the effect of dose reduction and the appropriate bolus thickness should be set up to reduce the dose in normal tissues.

방사선치료 기법의 발전으로 치료가 더욱 정밀해졌음에도 불구하고 치료 부위 외에도 방사선에 의해 피폭되는 것은 피할 수 없다. 이에 본 연구에서는 유방암의 방사선치료 시 치료 반대편 유방의 bolus 두께에 따른 흡수선량을 평가하고 선량 저감 효과에 대해 분석하고자 하였다. 실험 및 방법으로 Rando phantom을 대상으로 VMAT 치료방법을 이용하여 실험을 진행하였다. 치료 반대편 유방에 A, B, C, D, E의 5개 지점을 선정하여 bolus를 사용하지 않았을 때와 5, 10, 15, 20 mm의 bolus를 사용하였을 때의 선량을 유리선량계를 사용해 평가하였다. 그 결과, 치료지점과 가장 가까운 지점에서 높은 흡수선량이 측정되었으며 치료지점과 가장 먼 B 지점에서는 가장 낮게 측정되었다. 평균 흡수선량은 bolus를 사용하지 않았을 때 8.61 cGy 그리고 두께에 따라 8.10, 7.94, 8.06, 8.10 cGy로 나타났다. 연구 결과 선량 저감 효과를 확인할 수 있었으며, 본 연구를 바탕으로 적절한 bolus 두께를 설정하여 정상조직의 선량 저감화를 위해 노력해야 할 것이다.

Keywords

BSSHB5_2018_v12n6_763_f0001.png 이미지

Fig. 1. Rando phantom.

BSSHB5_2018_v12n6_763_f0002.png 이미지

Fig. 2. Bolus(5 mm) and glass dosimeter(measuring point A, B, C, D, E).

BSSHB5_2018_v12n6_763_f0003.png 이미지

Fig. 3. Absorbed dose at measurement point.

Table 1. Dose comparison according to bolus thickness by 1 fraction dose

BSSHB5_2018_v12n6_763_t0001.png 이미지

Table 2. Dose comparison according to bolus thickness by total prescription dose

BSSHB5_2018_v12n6_763_t0002.png 이미지

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