ESTRO 2024 - Abstract Book

S5924

RTT - Service evaluation, quality assurance and risk management

ESTRO 2024

Figure 1. Workstation arrangement during oART MRgRT with the CPW tasks. For instance, in the re-contouring phase, the MP updates electronic densities, the RO re-contours the therapy target, and the RTT is responsible for reviewing the contouring done by automated tools for the OARs and manually adjusting them if needed. All the procedures occur simultaneously.

Material/Methods:

A sample of 51 consecutive patients treated with MRIdian (ViewRay, Cleveland, Ohio) system was considered for this analysis. The oART phase was followed by RO, MP, and RTT with more than 5 years of experience on the MRgRT system. Treatment time data were collected over a two-month period following the CPW implementation. The total treatment session time (T_tot) was evaluated as the time elapsed from the patient's entry into the treatment room to his exit. The time required for the following oART workflow steps was prospectively registered and split in 7 seven steps: patient entry (PIt); patient set-up (SUt), MR image matching (Mt); daily MR Re-contouring (Ct); daily MR Re-planning (Pt); treatment delivery (Dt) and patient exit (PEt). Total machine time (TM_tot) was assessed by subtracting from the total time (Ttot) the time each patient spent dressing and undressing (PIt+ PEt), as this variable may differ among centers based on their room architecture and availability of dedicated changing rooms. The results obtained were then compared with the findings in the existing literature in order to evaluate possible differences in the timing of oART-MRgRT.

Results:

180 oART treatment fractions were evaluated between February 2023 and April 2023, representing a range of diverse clinical indications, including Nodes (24%), Lung (21%), Rectum (18%), Pancreas (16%), Liver (11%), Other (4%), Adrenal (3%), and Prostate (2%). The majority (77%) of these treatment fractions were administered with stereotactic fractionation (dose per fraction > 5Gy), while 23% were administered with conventional fractionation. Time statistics of the different workflow steps is provided in Figure 2. Most of the time appeared to be dedicated to treatment delivery, with an average Dt of 0:17 ± 0:07. The plan adaptation time with the CPW was on average 11 minutes (Ct = 0:06±0:04 and Pt = 0:05±0:04). The mean Ttot for oART treatments was 0:43±0:12 and mean TM_tot was 0:37±0:11.

TM_tot difference was statistically significant (p < 0.05) between oART treatment delivery administered in Breath Hold Inspiration (BHI) with a mean time of 0:40 ± 0:12 and in Free Breathing (FB) with a mean time of 0:33 ± 0:08.