ESTRO 2024 - Abstract Book

S5586

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

ESTRO 2024

15 esophageal radiotherapy patients (Group A) were randomly selected (cervical: 4, thoracic: 6, abdominal: 5). All patients were positioned with a vac-bag (Klarity, China) underneath. SGRT system (AlignRT, UK) was used as a marker less positioning guidance. CBCT was acquired and shifts in 6 DOF were recorded. Another 15 esophageal patients’ (Group B) CBCT with the comparable criteria were retrieved retrospectively (cervical: 4, thoracic: 6, abdominal: 5). These patients were aligned using tattoos and skin markings previously. Both groups of CBCT data were calculated and compared.

Results:

A total of 347 and 357 CBCT images were analyzed for Group A and B. The average of positioning errors was calculated as table shown below. The result has shown that the positioning accuracy of Group A was superior to Group B and it was statistically significance in lateral, longitudinal, pitch and roll directions (P<0.05).

Absolute

Setup Error

Vrt (cm)

Lng (cm)

Lat (cm)

Yaw (deg)

Roll (deg)

Pitch (deg)

(Mean±SD)

Group A

0.16±0.12

0.17±0.14

0.16±0.15

0.55±0.46

0.53±0.43

0.64±0.51

Group B

0.18±0.16

0.31±0.25

0.21±0.20

0.51±0.48

0.94±0.62

1.24±0.94

p value

0.223

<0.001

<0.001

0.252

<0.001

<0.001

Conclusion:

Marker-less positioning workflow is accurate and consistent for esophageal radiotherapy patients despite it is not a superficial tumour. It can improve patient’s treatment experience with better cosmetic outcome and quality of life. Most importantly, it does not comprise treatment accuracy and possibly reduces the CBCT frequency in our center.

Keywords: non-superficial tumor, SGRT, accuracy

References:

1. Heinzerling JH, Hampton CJ, Robinson M, Bright M, Moeller BJ, Ruiz J, et al. Use of surface-guided radiation therapy in combination with IGRT for setup and intrafraction motion monitoring during stereotactic body radiation therapy treatments of the lung and abdomen. Journal of Applied Clinical Medical Physics 2020;21:48–55. https://doi.org/10.1002/acm2.12852. 2. Mueller B, Song Y, Chia-Ko W, Hsu H-Y, Zhai X, Tamas P, et al. Accuracy and Efficiency of Patient Setup Using Surface Imaging versus Skin Tattoos for Accelerated Partial Breast Irradiation. Advances in Radiation Oncology 2023;8:101183. https://doi.org/10.1016/j.adro.2023.101183.

3. Sarudis S, Karlsson A, Bäck A. Surface guided frameless positioning for lung stereotactic body radiation therapy. Journal of Applied Clinical Medical Physics 2021;22:215–26. https://doi.org/10.1002/acm2.13370.