The characteristics of dose at mass interface on lung cancer Stereotactic Body Radiotherapy (SBRT) simulation

10th International Seminar on Medical Physics; 1st AMDI International Oncology Symposium

物理学;医药卫生

Wulansari, I.H.^1 ; Wibowo, W.E.^2 ; Pawiro, S.A.^1

Departement of Physics, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, Depok, West-Java

16424, Indonesia^1

Radiotherapy Departement, National General Hospital Cipto Mangunkusumo, Jakarta

10430, Indonesia^2

关键词: Convolution algorithm;    Error prediction;    Gafchromic EBT;    Motion amplitudes;    Motion direction;    Prediction errors;    Stereotactic body radiotherapy;    Treatment planning systems;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/851/1/012028/pdf
DOI  :  10.1088/1742-6596/851/1/012028

学科分类：卫生学

来源: IOP

【 摘 要 】

In lung cancer cases, there exists a difficulty for the Treatment Planning System (TPS) to predict the dose at or near the mass interface. This error prediction might influence the minimum or maximum dose received by lung cancer. In addition to target motion, the target dose prediction error also contributes in the combined error during the course of treatment. The objective of this work was to verify dose plan calculated by adaptive convolution algorithm in Pinnacle3at the mass interface against a set of measurement. The measurement was performed using Gafchromic EBT 3 film in static and dynamic CIRS phantom with amplitudes of 5 mm, 10 mm, and 20 mm in superior-inferior motion direction. Static and dynamic phantom were scanned with fast CT and slow CT before planned. The results showed that adaptive convolution algorithm mostly predicted mass interface dose lower than the measured dose in a range of -0,63% to 8,37% for static phantom in fast CT scanning and -0,27% to 15,9% for static phantom in slow CT scanning. In dynamic phantom, this algorithm was predicted mass interface dose higher than measured dose up to -89% for fast CT and varied from -17% until 37% for slow CT. This interface of dose differences caused the dose mass decreased in fast CT, except for 10 mm motion amplitude, and increased in slow CT for the greater amplitude of motion.