Hayley Mack
Alfred Health Radiation Oncology
Radiation Therapist

Vanessa Panettieri
Medical Physicist
Alfred Health Radiation Oncology

Annette Haworth
Professor
University of Sydney

Jeremy Millar
Radiation Oncologist
Alfred Health Radiation Oncology

Bronwyn Matheson
Radiation Oncologist
Alfred Health Radiation Oncology

Max Hanlon
PhD Candidate
RMIT University

Rick Franich
Professor
RMIT University

Ryan Smith
Medical Physicist
Alfred Health Radiation Oncology

Background & Purpose.

High dose-rate (HDR) brachytherapy treatment verification is important, but technically difficult. Errors would have significant clinical impact on the patient. Pre-treatment imaging can provide information to ensure the implanted catheters are in the correct position prior to dose delivery. In vivo source tracking during treatment provides further verification that the treatment is delivered to the patient as prescribed.

We report a clinical study of our experience with our novel Brachytherapy Image-Guided Verification (BIGV) flat panel detector (FPD) based system for HDR prostate brachytherapy.

Materials & Method.

A FPD was mounted in our treatment couch. The patient was positioned with the target region (prostate) centred over the imaging area. Radio-opaque markers were inserted into selected catheters and we acquired an AP image of the implant for comparison with the treatment planning system (TPS). Treatment commenced after the correct planned catheter positions were confirmed. During treatment patient exit radiation was acquired with FPD imaging. The exact dynamically-tracked position of the source inside the patient was determined with image-processing and was compared to the treatment plan.

Results.

Well defined pre-treatment imaging geometry allowed registration with the TPS and quantitative evaluation of potential catheter displacement. Source tracking during treatment provided a visual verification that treatment was proceeding as planned. Processing of the delivered source dwell positions verified correct treatment plan delivery. Delivered dose was reconstructed to compare with the planned TPS dose.

Conclusion.

Visual in vivo source tracking provided confidence the planned treatment was delivered as prescribed and processing confirmed the treatment was delivered free of potential human related errors. The present and future of this system improves safety standards by allowing routine treatment verification in HDR brachytherapy across a range of clinical applications.


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