Simulation-free radiotherapy on the MR-linac in prostate cancer.

OBJECTIVES

The radiotherapy (RT) pathway faces bottlenecks. The Rapid Adaptive and Cost-Effective Radiotherapy (RACE) study evaluates the feasibility of using diagnostic MRI (dMRI) scans for planning prostate MRI-guided adaptive RT (MRIgART).

METHODS

We audited prostate cancer patients treated with 5-fraction (#) stereotactic body radiotherapy (SBRT) between March 2023 and January 2024, assessing dMRI for RT planning suitability. Planning suitability required a T2-weighted sequence for target/organs at risk (OAR) delineation and a large field-of-view (LFOV). Scans were classified as RT plan suitable or as having specific issues (incomplete body coverage or slice thickness >10 mm). Workflow analysis from RT referral to first fraction estimated potential time savings with simulation-free RT (SFRT). Case studies illustrated identified issues and proposed solutions.

RESULTS

dMRIs were available for 93% of patients, with scans originating from various hospitals and conducted on 1.5 Tesla (T) or 3 T MRI scanners. Ideal image characteristics for RT planning were met in 38% of MRIs. Issues such as cropped field of view (FOV) and low slice resolution were identified, but proposed solutions could increase the number of patients with suitable scans to 87%.

CONCLUSIONS

The findings suggest that with appropriate technical solutions, most dMRI scans can be adapted for RT planning purposes.

ADVANCES IN KNOWLEDGE: The study highlights the potential of SFRT to reduce treatment delays and improve cost-effectiveness.