Manual treatment planning in brachytherapy is time-consuming and highly dependent on the skill of the planner. To be able to perform the planning efficiently and to give the patient the best possible brachytherapy treatment, new methods need to be developed. New methods need to be validated carefully. This thesis aims to validate and advance high dose-rate brachytherapy planning methods.

Current treatment planning methods were studied and used for comparison. An in-house-developed post-adjustment tool was validated for prostate brachytherapy, with the goal to reduce high-dose volumes while preserving target coverage and avoiding increased organ-at-risk doses. Additionally, an inverse treatment planning method for cervical brachytherapy was developed using clinically available optimisation tools.

Validation was performed using established and novel dose metrics, supported by oncologist’s observer studies. Statistical methods from diagnostic radiology were adapted for comprehensive analysis of the observer studies—marking their first application in radiation therapy.

Results confirmed that the post-adjustment tool effectively reduced high-dose volumes in prostate brachytherapy, while preserving the target coverage and the dose to the organs-at-risk. The inverse cervical brachytherapy method was successfully implemented in two clinical systems, with treatment plans scored equal to manual plans in the observer study. These two new methods could make it possible to use inverse methods for cervical brachytherapy, and to perform inverse prostate brachytherapy without manual adjustments. This will make the treatment planning process faster and less dependent on the skill of the treatment planner.