Effects of body contours on the setup errors of the Catalyst HD optical surface imaging system-guided radiotherapy
10.3760/cma.j.issn.112271-20221212-00482
- VernacularTitle:不同部位体表轮廓对Catalyst HD体表光学系统引导放疗摆位的影响
- Author:
Xinyao DAI
1
;
Yu CHENG
;
Panpan CAO
;
Haiyan PENG
;
Fu JIN
Author Information
1. 重庆大学附属肿瘤医院肿瘤放射治疗中心，重庆 400030
- Keywords:
Radiotherapy;
Surface guided radiotherapy;
Catalyst HD;
Body surface contour;
Setup error
- From:
Chinese Journal of Radiological Medicine and Protection
2023;43(9):689-697
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To explore the influence of the contours of different parts of the human body on the setup errors of Catalyst HD optical surface imaging (OSI) system-guided radiotherapy.Methods:Using the 3D printing technology, arc- and oval arc-shaped phantoms with base angles of 5°-45° (step length: 5°) were designed to simulate the contours of different body parts of patients. A Catalyst HD system was employed for monitoring, during which the gains and integration time of the system were adjusted. The treatment couches were manually moved (range: -5 mm to 5 mm, with a step length of 2 mm). The ratios of transverse to longitudinal dimensions of all phantoms were recorded. The recorded items also included couch value errors in the anterior-posterior (AP), inferior-superior (SI), and left-right (LR) directions for transversely and longitudinally placed phantoms, as well as the setup errors monitored using the Catalyst HD system. Then, this study presented an analysis of the correlation between phantoms for different body contours and the gains and integration time of the Catalyst HD system. The purpose was to compare the setup errors under the two different placement conditions of phantoms and to analyze the correlation between the monitored values of the Catalyst HD system and couch values.Results:There was a significant linear negative correlation between the gain and the logarithm of integration time required for monitoring using the Catalyst HD system, with a slope of -0.001. There was a certain functional relationship between the intercept and the ratio of the transverse to longitudinal dimensions of the phantoms. Under the same gain, the integration time decreased with an increase in the base angles of phantoms. The Catalyst HD system showed different monitoring accuracy under different placement conditions of the phantoms ( Z = -8.59 to -0.02, P < 0.05), with the monitoring accuracy in the LR and AP directions higher in the transverse position. The correlation between the monitored values of the Catalyst HD system and the actual couch values increased in the LR and SI directions with an increase in the base angle of the phantoms, showing a strong correlation in the case of base angles of ≥ 25°. Furthermore, the correlation was always significant in the AP direction ( R > 0.9). Conclusions:When the best surface images are obtained using the Catalyst HD system, the gains and integration time of the system are correlated with body surface contours. The Catalyst HD system shows high monitoring accuracy in the AP direction. This system shows high accuracy in all directions when the ratios of transverse to longitudinal dimensions are ≤ 2 or the base angles ≥ 25°.
