Optimizing the target detectability of cone beam CT performed in image-guided radiation therapy for patients of different body sizes.

Purpose: The target detectability of cone beam computed tomography (CBCT) performed in image-guided radiation therapy (IGRT) was investigated to achieve sufficient image quality for patient positioning over a course of treatment session while maintaining radiation exposure from CBCT imaging as low as reasonably achievable (ALARA).

Methods: Body CBCT scans operated in half-fan mode were acquired with three different protocols: CBCT , CBCT , and CBCT , which resulted in weighted CT dose index (CTDI ) of 0.36, 1.