Analysis of different fixation devices in precision radiotherapy for prostate cancer under bowel and bladder preparation protocol
10.3760/cma.j.cn113030-20210802-00282
- VernacularTitle:肠道膀胱准备下不同固定方式对前列腺癌精准放疗影响
- Author:
Sijuan HUANG
1
;
Ziyue ZHONG
;
Hao TANG
;
Yang LIU
;
Mengxue HE
;
Xuan GUO
;
Liru HE
;
Zhiyue LIN
;
Wenyan YAO
;
Senkui XU
;
Xin YANG
Author Information
1. 中山大学肿瘤防治中心/华南肿瘤学国家重点实验室/肿瘤医学协同创新中心/广东省鼻咽癌诊治研究重点实验室，广州 510060
- Keywords:
Prostatic Neoplasms;
Fixation;
Setup error;
Bowel and bladder preparation protocol
- From:
Chinese Journal of Radiation Oncology
2022;31(8):716-721
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To provide evidence for the selection of fixation devices and CTV to PTV margins (M ptv) in precision radiotherapy for pelvic tumors by analyzing three fixation devices in precision radiotherapy for prostate cancer. Methods:From April 2015 to December 2020, 133 prostate cancer patients treated with pelvic drainage area irradiation in our center were retrospectively analyzed. The patients were fixed with 1.2m vacuum bag (n=39), 1.8m vacuum bag (n=44) and personalized prone plate by our center (n=50). Each patient was asked to complete our bowel and bladder preparation process before positioning and radiotherapy. The registration of CBCT to planned CT before each treatment adopted the same registration box and algorithm. Setup errors in the SI, LR and AP directions under qualified bowel and bladder conditions were recorded. Setup errors in three directions under three fixation devices and corresponding M ptv values were analyzed. The correlation between setup errors with age and body mass index (BMI) was analyzed. Results:Analysis of 3333 setup errors data showed: in the SI and LR directions, the mean setup errors of 1.2m vacuum bag (3.26mm, 2.34mm) were greater than those of 1.8m vacuum bag (2.51mm, P<0.001; 1.90mm, P<0.001), and personalized prone plate (3.07mm, P=0.066; 2.10 mm, P=0.009). In the AP direction, the mean setup errors of 1.2m vacuum bag (supine)(2.20mm) were smaller than those of 1.8m vacuum bag (3.33mm, P<0.001) and personalized prone plate (3.61mm, P<0.001). The setup errors of 1.8m vacuum bag in all directions were smaller than those of personalized prone plate (P≤0.028). According to Van Herk's expansion formula, the M ptv of 1.2m vacuum bag in three directions was approximately 4 mm. The M ptv of 1.8m vacuum bag and personalized prone plate in the SI and LR directions was approximately 3 mm, and more than 5 mm in the AP direction. The setup errors were not correlated with age or BMI. Conclusions:From the setup errors results of three devices, 1.8m vacuum bag is the best, followed by personalized prone plate. And supine position is better than prone position in the AP direction.
