3D BrachyView System

Prostate cancer is quickly becoming the most common form of cancer across the globe, and is commonly treated with low dose rate brachytherapy due to its curative measures and highly conformal dose delivery. It is important to ensure there is a means of real time monitoring of the dose and seed placements when radioactive seeds are implanted in the prostate gland during a low dose rate brachytherapy treatment. The BrachyView system presents as a unique system that provides the capability of 3D seed reconstruction within an intraoperative setting. In this thesis the BrachyView system is tested for its suitability, accuracy and the system is further developed so that its application in real-time intraoperative dosime-try can become a reality. The system was tested with a clinically relevant number of seeds, 98, where previously the system had only been tested with a maximum number of 30 seeds. The BrachyView system was able to reconstruct 91.8% of implanted seeds from the 98 seed dataset with an average overall discrepancy of 3.65 mm without the application of the baseline subtraction algorithm, however with its application to the data the detection efficiency was improved to 100% and an overall positional accuracy of 11.5%, correlating to a reduced overall discrepancy of 3.23 mm, was noted. It was found that with seed numbers of 30 or lower that the addition of a background subtrac-tion algorithm was not necessary, whereas for datasets containing a clinically relevant number of seeds the application of a background subtraction algorithm was paramount to reducing the noise, scatter and means for identification of newly implanted seeds that may be masked by those seed previously implanted

BrachyView: Verification of LDR patient plans - Hardware optimisation

BrachyView is a novel in-body imaging system developed with the objective to provide real-time intraoperative dosimetry for low dose rate (LDR) prostate brachytherapy treatments. Seed positions can be reconstructed after implantation by the means of a high-resolution pinhole gamma camera. The obtained dataset is then combined with conventional trans-rectal ultrasound (TRUS) imaging to locate the effective source position within the prostate volume. This study presents a comparison of two data sets containing 96 and 98 I-25 brachytherapy sources and readout by two different pin-hole collimators with 800 m and 500 m, respectively. This study aims to assess the effect on reconstruction of large pinholes which allow for large Field of View (FoV) and statistics of counts on the seed\u27s projections. It was found that 100% of seeds were reconstructed by the means of the 500 m collimator. Results from the 800 m data showed that only 70% of seeds were reconstructed with a total 3D discrepancy of 8.20 mm in respect to CT data and an increased reconstructed position inaccuracy

BrachyView: Reconstruction of seed positions and volume of an LDR prostate brachytherapy patient plan using a baseline subtraction algorithm

Purpose: BrachyView is a novel in-body imaging system developed with the objective to provide real-time intraoperative dosimetry for low dose rate (LDR) prostate brachytherapy treatments. The BrachyView coordinates combined with conventional transrectal ultrasound (TRUS) imaging, provides the possibility to localise the effective position of the implanted seeds inside the prostate volume, providing a unique tool for intra-operative verification of the quality of the implantation. This research presents the first complete LDR brachytherapy plan reconstructed by the BrachyView system and is used to evaluate the effectiveness of an imaging algorithm with baseline subtraction. Methods: A plan featuring 98 I-125 brachytherapy seeds, with an average activity of 0.248 mCi, were implanted into a prostate gel phantom under TRUS guidance. Images of implanted seeds were obtained by the BrachyView after the implantation of seeds. The baseline subtraction algorithm is applied as a pixel-to-pixel counts subtraction and is applied to every second projection obtained after the implantation of each needle. Seed positions and effectiveness of the baseline reconstruction in the identification of seeds were verified by a high-resolution post-implant CT scan. Results: A complete brachytherapy plan has been reconstructed with a 100% detection rate. This is possible due to the effectiveness of the baseline subtraction, with its application an overall increase of 11.3% in position accuracy and 8.2% increase in detection rate was noted. Conclusion: It has been demonstrated that the BrachyView system shows the potential to be a solution to providing clinics with the means for intraoperative dosimetry for LDR prostate brachytherapy treatments

BrachyView: Development of an algorithm for real-time automatic LDR brachytherapy seed detection

© 2020 Institute of Physics and Engineering in Medicine. BrachyView is a novel in-body imaging system developed to provide real-time intraoperative dosimetry for low dose rate prostate brachytherapy treatments. Seed positions can be reconstructed after in-vivo implantation using a high-resolution pinhole gamma camera inserted into the patient rectum. The obtained data is a set of 2D projections of the seeds on the image plane. The 3D reconstruction algorithm requires the identification of the seed\u27s centre of mass. This work presents the development and techniques adopted to build an algorithm that provides the means for fully automatic seed centre of mass identification and 3D position reconstruction for real-time applications. The algorithm presented uses a local feature detector, speeded up robust features, to perform detection of brachytherapy seed 2D projections from images, allowing for robust seed identification. Initial results have been obtained with datasets of 30, 96 and 98 I-125 brachytherapy seeds implanted into a prostate gel phantom. It can detect 97% of seeds and correctly match 97% of seeds. The average overall computation time of 2.75 s per image and improved reconstruction accuracy of 22.87% for the 98 seed dataset was noted. Elimination processes for initial false positive detection removal have shown to be extremely effective, resulting in a 99.9% reduction of false positives, and when paired with automatic frame alignment and subtraction procedures allows for the effective removal of excess counts generated by previously implanted needles. The proposed algorithm will allow the BrachyView system to be used as a real-time intraoperative dosimetry tool for low dose rate prostate brachytherapy treatments