Setup time analysis for stereotactic body radiotherapy in O-ring linear accelerator without rotational correction.

Area of Science:

• Radiation Oncology
• Medical Physics

Background:

• Stereotactic body radiotherapy (SBRT) requires precise patient positioning.
• The absence of automatic rotational correction presents challenges in setup accuracy.

Purpose of the Study:

• To analyze setup time (ST) and on-board imaging frequency in SBRT for abdomen, lung, and spine.
• To evaluate the impact of rotational errors on SBRT setup without automatic correction.

Main Methods:

• Retrospective analysis of 53 SBRT patients (28 abdomen, 19 lung, 6 spine) treated over 230 sessions.
• Evaluation of setup time and Cone-Beam CT (CBCT) frequency using an O-ring gantry accelerator.

Main Results:

• Mean ST: 7.7±7.4 min overall; 9.2±9.2 min (abdomen), 6.3±4.1 min (lung), 5.5±3.3 min (spine).
• Median CBCT use was 2 per patient; 96% received 1-3 CBCTs.
• Setup times predominantly fell within 0-20 minutes (95.7%).

Conclusions:

• Managing rotational errors is a key challenge in SBRT without automatic correction.
• Accurate knowledge of rotational errors can facilitate treatment delivery.
• Setup times are generally manageable, but rotational errors require careful consideration.