3D Printed Custom Applicators for HDR BT (DISCO)

To demonstrate the feasibility of successfully simulating, planning and treating a HDR BT gynaecological patient with a 3D-printed internal mould, such that there is a dosimetric and/or clinical benefit for the patient relative to the current standard of care (cylindrical vaginal applicator). Successful treatment indicated by achieving no adverse events or difference to standard of care, and dosimentic comparisons of the 3D printed applicator plan to the cylinder plan are equivalent or better. Feasibility also determined by achieving no logistical or design issues in using the 3D printed applicators clinically.

RT acute and late side effects will be assessed and quantified using CTCAE criteria via clinician assessment and PROs

The plan quality of treatment plans generated for 3D-printed moulds and cylindrical applicators will be compared using dosimetric indices including target coverage (D90, Dose Homogeneity index) and organs at risk doses (D2cc, D1cc and point max) as well as patient comfort. statistical analysis (p-value) and comparison with international guidelines will be used to assess the quality of the treatment plans.

Feasibility of a pre-planned MR-only procedure will be determined using any of the patients that are accrued to the study who have both a CT and MRI performed at the time of simulation. The applicator and treatment plan will be generated based on the MRI and both compared to the CT-based plan and applicator. Feasibility will be indicated by generating equivalent plan quality and applicators from both methods.

The initial and final CT plan dosimetry will be compared to determine the feasibility of an initial CT-only process. Clinically insignificant differences between the plan dosimetry metrics and all within clinical tolerances will be used to quantify the difference. statistical analysis (p-value) will be used to assess the quality of the treatment plans.

The feasibility of an optimised 3D-printed applicator design based on the cylinder fitting procedure will be assessed by comparison of the 3D-printed clinical applicators with applicators derived from CT/MR of the vault in a relaxed state with an expansion applied based on the size of the cylinder applied in the fitting procedure. Feasibility will be determined by looking for a correlation between the size of the 3D printed clinical applicators and the size of the cylinders tolerated by the patient in the fitting procedure.

Procedure times will be recorded as per ARIA carepath tasks and time taken within the 3D-printed custom applicator workflow compared to the standard of care cylinder applicator workflow with equivalent or less time taken deemed acceptable

Costs associated with the 3D-printed design process will be defined and compared with the standard of care process via economic analysis of the resourcing and unit-price estimates in each arm of the respective workflows

Patient experience and acceptability of the 3D-printed simulation and treatment processes will be assessed with the EORTC QLQ-C30 questionnaires and success measured by comparison with the standard of care vaginal cylinder process. Questionnaires include questions with a scale of 1-4 where a higher number indicates a worse experience and a scale of 1-7 where a lower number indicates a worse experience.