|
KMID : 1164220180300010017
|
|
Journal of Korean Society for Radiotherapeutic Technology
2018 Volume.30 No. 1 p.17 ~ p.25
|
|
|
Dosimetric comparison for Prostate VMAT of weight and photon energy change
|
|
Jo Guang-Sub
Kim Min-Woo
Baek Min-Gyu
Chae Jong-Pyo
Ha Se-Min
Lee Sang-Bong
|
|
|
Abstract
|
|
|
Purpose : To compare the radiation doses of prostate cancer patients according to changes in abdominal body shape and energy during Volumetric modulated arc therapy(VMAT).
Materials and Methods : Seven patients with prostate cancer were enrolled in this study. VMAT treatment plan was established at 6, 10, and 15 MV while changing from -2.0 cm to 2 cm by 0.5 cm. Conformal index(CI), homogeneous index(HI), Dmax, D95 %, D50 % and D2 % of PTV were examined in order to evaluate the change of dose in the target organ according to body shape change. Normal organ of the femoral head, rectum and bladder was analyzed to evaluate dose changes.
Results : The dose of Dmax 6 MV in PTV increased to 107.2 % in 1.0 cm body shape reduction, and 10 MV and 15 MV dose increased to 107.1 % and 107.0 % in 1.5 cm body reduction, respectively. The dose of D50 % 6 MV in PTV decreased to 99.64 % in 1.0 cm body shape increase, and in 10 MV and 15 MV dose decreased to 99.79 % and 99.97 % in 1.5 cm body increase, respectively. In 2.0 cm body type increase, the dose was decreased to 99.30 % and 99.52 %, respectively. Doses for rectum and bladder gradually increased with decreasing weight, and dose decreased with decreasing weight. 6 MV, and V70Gy at 10 MV increased from 11.50 % to 12.76 % when the external shape decreased by 2.0 cm. The bladder V70Gy also increased from 14.0 % to 15.2 %. It was also shown that the dose increased as the body weight decreased in the femoral head.
Conclusion : In the treatment of VMAT, dose distribution can be changed according to the change of abdominal shape. SSD and CBCT were used to decrease the body shape by more than 1cm or more than 1.0 cm at 6 MV and the body shape by more than 1.5 cm or more than 1.5 cm at 10 MV or 15 MV. It is considered that a new treatment plan should be established through re-simulation.
|
|
|
KEYWORD
|
|
|
body shape change, Volumetric modulated arc therapy, Prostate Cancer
|
|
|
FullTexts / Linksout information
|
|
|
|
|
Listed journal information
|
|
|
|
|