The feasibility of real-time biologically adaptive trans-rectal ultrasound-based high-dose-rate prostate brachytherapy

High dose rate prostate brachytherapy (HDRPBT) is a treatment that is performed by inserting hollow catheters through the perineum and into the prostate, followed by insertion of a radioactive source into the catheters to generate a 3-dimensional radiation dose distribution in the prostate. HDRPBT treatments can be planned using either computed tomography (CT) based planning or real-time transrectal ultrasound (TRUS) based planning. Clinically, HDRPBT has shown improved clinical outcomes when used as a dose boost in conjunction with external beam radiation therapy (EBRT) compared to HDRPBT alone. Regardless of the HDRPBT regimen, the geometric accuracy of treatment delivery is one of the most important parameters for tumour control and acute/late effects. Importantly, the geometric position of the delivered radioactive source needs to align closely with the geometric position in the treatment planning system (TPS), inaccuracy in delivered source position compared to planned source position can lead inadequate biochemical progression free survival and increased dose to organs at risk (OAR) potentially causing acute and/or late effects.

Currently, for HDRPBT there is a deficiency of clinically available treatment verification. EBRT has several different treatment verification mechanics such as image guidance and gated breathing techniques that HDR brachytherapy does not have. Therefore, there are two current shortcomings for HDRPBT that many research groups are attempting to solve; the lack of in-vivo source tracking (IVST) and image guidance clinically (analogous to image guided radiation therapy), and lack of solutions for treatment adaptation based on IVST (when to modify and interrupt treatment if detected errors are too large from the expected TPS source positions).

The aim of this thesis is to investigate potential approaches to utilising IVST information for a clinical benefit. This will be achieved by optimising, modifying and analysing patient DICOM data using both the TPS and independent software. Additionally, the aim is to further develop the Magic Plate 987 produced by the Centre for Medical Radiation physics to prepare it for robust and accurate IVST.