ESTRO 2025 - Abstract Book

S4072

RTT - Patient care, preparation, immobilisation and IGRT verification protocols

ESTRO 2025

Eliminating rectal preparation did not significantly increase rectal volume, inter or intrafraction motion, providing confidence to continue without invasive preparation. Wider impact on patient and hospital burden will be investigated.

Keywords: Rectal preparation, prostate cancer, motion, IGRT

1854

Digital Poster The application of SGRT on pediatrics radiation therapy fei jiang, xiansong sun, ke hu, jie qiu, fuquan zhang Radiotherapy, Peking Union Medical College Hospital, beijing, China

Purpose/Objective: Body thermoplastic is our main immobilization solution for pediatric radiation therapy in our department. However, the tightness of the thermoplastic may cause patient’s discomfort and some of the sedated patients were awakened when the thermoplastic is locked which may disrupt the treatment workflow. Hence, we would like to investigate the potential of the use of SGRT with customized polyurethane foam casting in pediatric cases. Material/Methods: 14 pediatric patients (age range: 2-13-year-old) with 16 malignancies (head and neck:1, thorax:4, pelvis:7, upper limb:2 lower limb:2) were selected randomly. Customized polyurethane foam casting was introduced for all the patients. Patients were positioned guided by SGRT system to the threshold of less than 1mm and 1 degree. Daily CBCT was acquired. 6D positioning errors and pre-CBCT SGRT delta values were recorded, and the real time intra fractional monitoring data was retrieved. SPSS 21.0 was used for data analysis. Results: A total of 227 fractions of CBCT and SGRT data were analyzed. Wilcoxon Signed-Rank test was used as the positioning errors data of both CBCT and SGRT were not normally distributed (Shapiro-Wilk test). The result (Table 1) showed statistically significant (p<0.01) in lateral, longitudinal, vertical and pitch directions. Spearman correlation analysis (Table 2) has shown strong correlation in all six directions. The mean and standard deviation of intra-fractional motion were 0.01±0.04cm, -0.01±0.06cm, 0.01±0.04cm, -0.02±0.32° ， 0.09±0.54° ， -0.03±0.3° in lateral, longitudinal, vertical, pitch, roll and yaw directions. None of the patients moved beyond the threshold value (±3mm/3°) during the treatment.

Table 1 Statistical analysis of CBCT and SGRT positioning errors of 14 pediatric patients Spatial Direction CBCT SGRT Z p

＜ 0.01

Lateral (cm)

0.14(0.04,0.21)

0.07(0.03,0.09)

-10.983

＜ 0.01

Longitudinal (cm)

0.19(0.07,0.27)

0.11(0.03,0.16)

-12.535

＜ 0.01

Vertical (cm)

0.17(0.06,0.26)

0.11(0.03,0.16)

-11.887

＜ 0.01

Pitch (°)

0.46(0.20,0.7)

0.54(0.30,0.70)

-5.665

Roll (°)

0.55(0.2,0.8)

0.53(0.30,0.70)

-2.189

0.029

Yaw (°)

0.42(0.20,0.60)

0.44(0.20,0.60.0 -2.231

0.026

Table 2 Correlation analysis of CBCT and SGRT positioning errors of 14 pediatric patients