Evaluating the feasibility of palliative radiotherapy planning for symptomatic bone metastases using diagnostic...

Patients with symptomatic bone metastases often require urgent palliative radiotherapy, yet conventional treatment planning workflows involving computed tomography (CT) simulation can delay the treatment planning. The purpose of this study is to utilize diagnostic CT for palliative radiotherapy treatment planning in patients with bone metastases in order to reduce the time between physician consultation and treatment planning.

We retrospectively collected data from 27 eligible patients treated for bone metastases at Mount Sinai Hospital between April 2020 and May 2023. From the original treatment plans, contours, beam arrangements, and administered monitor units (MUs) were transferred from the planning CT to the diagnostic CT for dose calculation. Plan quality was evaluated using target volume coverage metrics, including planning target volume (PTV) V95%, PTV mean dose, and global hotspots.

Out of all the patients in our database, four patients were excluded due to absence of a prior diagnostic CT scan, and three patients were excluded since the entire target volume was not within the diagnostic CT field of view. In total, 26 treatment plans from 20 patients were compared with the original plans. The potential reduction in wait time was estimated by subtracting the average time from initial consult to CT simulation, which was approximately 6.5±1.2 days in this cohort. For all 26 diagnostic CT plans, the mean PTV V95% was 95.3%±0.2%. Compared to the original plans, mean V95% decreased by 1.3%±0.7% and global hotspots increased by 1.80%±0.004% in the diagnostic CT plans.

Our study demonstrated that treatment planning with diagnostic CT is feasible in the palliative radiotherapy setting for patients with bone metastases. This approach may reduce the time between physician consultation and treatment planning, thereby enabling timely relief for patients with symptomatic bone metastases.