Verification of motion induced thread effect during tomotherapy using gel dosimetry

8th International Conference on 3D Radiation Dosimetry

Edvardsson, Anneli^1 ; Ljusberg, Anna^1 ; Ceberg, Crister^1 ; Medin, Joakim^2 ; Ambolt, Lee^2 ; Nordström, Fredrik^2 ; Ceberg, Sofie^2

Medical Radiation Physics, Lund University, Lund, Sweden^1

Radiation Physics, Skåne University Hospital, Lund, Sweden^2

关键词: Absorbed dose distribution;    Breathing motions;    Gel dosimetry;    Motion devices;    Motion function;    Polyacrylamide gels;    Spiral pattern;    Static modes;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/573/1/012048/pdf
DOI  :  10.1088/1742-6596/573/1/012048

来源: IOP

【 摘 要 】

The purpose of the study was to evaluate how breathing motion during tomotherapy (Accuray, CA, USA) treatment affects the absorbed dose distribution. The experiments were carried out using gel dosimetry and a motion device simulating respiratory-like motion (HexaMotion, ScandiDos, Uppsala, Sweden). Normoxic polyacrylamide gels (nPAG) were irradiated, both during respiratory-like motion and in a static mode. To be able to investigate interplay effects the static absorbed dose distribution was convolved with the motion function and differences between the dynamic and convolved static absorbed dose distributions were interpreted as interplay effects. The expected dose blurring was present and the interplay effects formed a spiral pattern in the lower dose volume. This was expected since the motion induced affects the preset pitch and the theoretically predicted thread effect may emerge. In this study, the motion induced thread effect was experimentally verified for the first time.