Comparison of initial patient setup accuracy between surface imaging and three point localization: A retrospective...

Area of Science:

• Radiation Oncology
• Medical Imaging
• Patient Positioning

Background:

• Traditional patient positioning in radiation therapy relies on subcutaneous tattoos for alignment.
• These tattoos can deviate, leading to inaccuracies in patient setup and requiring image-guided corrections.
• Surface-based imaging offers an alternative by using the entire skin surface for positioning verification.

Purpose of the Study:

• To retrospectively compare the accuracy of patient positioning using surface imaging (C-RAD CatalystHD) versus traditional tattoos.
• To evaluate the magnitude of cone-beam computed tomography (CBCT)-based 3D corrections required for each positioning method.

Main Methods:

• A total of 6000 individual radiation therapy fractions were analyzed.
• Patient positioning data from both tattoo-based and C-RAD CatalystHD surface imaging methods were compared.
• Four treatment sites were evaluated: pelvis/lower extremities, abdomen, chest/upper extremities, and breast.
• Statistical analysis used a paired sample Wilcoxon signed-rank test (P < 0.01).

Main Results:

• Patients positioned with C-RAD CatalystHD required significantly smaller average 3D shift corrections across all evaluated sites compared to those positioned with tattoos.
• Average 3D shift magnitudes for tattoos ranged from 0.9 ± 0.4 cm to 1.4 ± 0.7 cm.
• Average 3D shift magnitudes for CatalystHD ranged from 0.5 ± 0.3 cm to 0.6 ± 0.3 cm.
• Statistically significant differences (P < 0.01) in 3D shifts were observed for all treatment sites.

Conclusions:

• Surface imaging systems, such as C-RAD CatalystHD, result in significantly smaller patient positioning corrections than traditional subcutaneous tattoos.
• Surface-based imaging is a viable and potentially preferable alternative for initial patient setup in radiation therapy.
• This technology may offer improved accuracy and efficiency in radiation treatment delivery.