An evaluation of isocentre shift magnitude and treatment site on image-guided radiation therapy online decision analysis times.

Abstract

The ability to capture more anatomical detail in cone-beam computed tomography (CBCT) imaging compared to kilovoltage (kV) and megavoltage (MV) imaging, has seen a documented shift towards CBCT image verification and staff adopting more extensive image analysis processes. The timeframe associated with assessing online CBCT images, termed the online decision analysis time, if drawn out, can affect treatment efficiency and accuracy. This study aimed to determine the current CBCT online decision analysis time at Radiation Oncology Princess Alexandra Ipswich Road (ROPAIR) and investigate the influence of isocentre shift magnitude and treatment site considerations on this timeframe. This retrospective clinical audit collected treatment parameters from 202 CBCT images over 2 treatment days. The online decision analysis time was calculated by subtracting the image acquisition timestamp from the image verification shift application timestamp. The quantitative data were analysed using mean, standard deviation, and range in the following categories: all CBCTs, CBCTs grouped by isocentre shift magnitude and CBCTs grouped by treatment site. Content analysis was performed on staff comments made during image analysis. The average online decision analysis time was 2:37 ± 1:28 min. On average approximately, head and neck, spine and extremity treatment sites measured 1 min, pelvis, breast, and chest measured 2-3 min with abdomen measuring 4 min. Common categories reported in staff comments included anatomical changes, repositioning, and organs at risk size. The results provide baseline online decision analysis times. Further refinement is required to determine if the image match method, treatment site considerations, and rotational discrepancies influence this timeframe.