Saree Alnaghy
Centre for Medical Radiation Physics, University of Wollongong
PhD Student

Mitra Safavi-Naeini
Research Associate ANSTO
Centre for Medical Radiation Physics, University of Wollongong

Dean Cutajar
Research Associate Post Doc
Centre for Medical Radiation Physics, University of Wollongong

Stuart George
Research Associate Post Doc
Centre for Medical Radiation Physics, University of Wollongong

Andrew Howie
Senior Medical Physicists
St George Cancer Care Centre, St George Hospital

Andre Bece
Radiation Oncologist Register
St George Cancer Care Centre, St George Hospital

Joseph Bucci
Radiation Oncologist
St George Cancer Care Centre, St George Hospital

Jan Jakubek
Chief scientist Advacam s.r.o
Institute of Experimental and Applied Physics, Czech Technical University of Prague

Stanislav Pospisil
Director Institute of Experimental and Applied Physics
Institute of Experimental and Applied Physics, Czech Technical University of Prague

Michael Lerch
Head of Physics
Centre for Medical Radiation Physics, University of Wollongong

Marco Petasecca
Senior lecturer
Centre for Medical Radiation Physics, University of Wollongong

Anatoly Rosenfeld
Director of CMRP
Centre for Medical Radiation Physics, University of Wollongong

Background/Purpose In high dose rate (HDR) prostate brachytherapy, accurate source placement within the prostate is vital in providing excellent dose coverage of the prostate. Current imaging techniques for seed position verification are limited in either spatial resolution or ability to provide source positioning information during treatment. BrachyView is a novel, in-body imaging system which aims to provide, high-resolution source tracking in HDR brachytherapy during intraoperative treatment. The major focus of this study was a pre-clinical evaluation of the developed real-time reconstruction software and image fusion between Transrectal ultrasound (TRUS) and BrachyView. Methods The BrachyView probe consists of a tungsten cylindrical shell with seven double cone pinholes drilled into the surface of the probe. The pinholes have a diameter of 0.5 mm with a tungsten thickness 4 mm. An edgeless quad hybrid pixilated silicon detector, Timepix is assembled and embedded within the tungsten collimator. Each detector has a size of 256 × 256 pixels, with a pixel size of 55 × 55 µm2. A full HDR treatment plan was administered within a CIRS tissue-equivalent ultrasound prostate gel phantom. TRUS was used to image the prostate. The BrachyView probe was placed in-phantom to track the HDR dwell positions in real-time. A CT scan of the experimental configuration was performed. CT data of the experimental configuration were used along with the treatment planning system to determine the planned dwell locations. Image co-registration between the BrachyView and TRUS coordinate system was also performed using the CT dataset. Results The temporal resolution of the BrachyView system showed a minimum frame rate of 0.28 s/frame, limiting source reconstruction to dwell times greater than 0.3 s, resulting in reconstruction of 175 source dwell positions out of a possible 200. Discrepancies between the planned locations and the BrachyView system were found to be within 1 mm for 78% of the 175 reconstructed dwell positions. A successful fusion between the reconstructed source locations and prostate volume was performed using the developed 3D visualisation software. Conclusion BrachyView data showed excellent agreement with the planned dwell positions with 78% of the reconstruction falling within submillimeter of their nominal location. This study shows the BrachyView system is capable of tracking the HDR source in real-time when overlaid with the TRUS images, it provides dwell position and anatomical information without the need of external radiation imaging for source position verification.


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