ESTRO 37 Abstract book

ESTRO 37

S579

Figure: Cost-Effectiveness Analysis Curves

implantation by the means of a high-resolution pinhole gamma camera 1 . The BrachyView dataset combined with conventional 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. An imaging algorithm for baseline subtraction has been implemented to allow for the reconstruction of a full treatment plan with 98 seeds implanted. The overall accuracy of the seed recon- struction algorithm is tested against a CT scan of the phantom after the completion of the implantation. Material and Methods The probe consists of a 1mm thick tungsten cylindrical collimator, containing three single cone pinholes of 500µm in diameter, situated above three Timepix pixelated silicon detectors. To assess the capabilities of the BrachyView system an LDR treatment plan consisting of 98 seeds (I-125 with average activity of 0.248mCi) were implanted into a prostate gel phantom. TRUS images, automatic segmentation and rendering were performed to reconstruct the 3D shape and position of the prostate, utilising transversal 2.5mm thick ultrasound slicing. BrachyView data was acquired for three minutes after each needle implantation to compensate for the low activity of the seeds. A CT study with O-MAR (orthopaedic metal artefact reduction) was completed post implantation to provide a reference for comparison of the BrachyView reconstructed seed positions. Results When compared to the seed positions obtained by the CT scan the BrachyView seed reconstruction showed that the average discrepancies were 2.4 mm, 1.35 mm and 1.2 mm in the x, y and z coordinate directions, respectively. Where 74% and 95% of the seeds are reconstructed within 1.5 mm and 2.0 mm of discrepancy, respectively. Seeds are also co-registered with the TRUS 3D image and displayed within the prostate volume.

Conclusion WW CXB

is likely to be cost-effective compared to both alone and RS. These findings support the use of

WW EBRT

CXB boost as an adjunct to a WW strategy.

Poster: Brachytherapy: Miscellaneous

PO-1030 BrachyView: verification of a full LDR brachytherapy patient plan in a prostate gel phantom T. Brennen 1 , M. Petasecca 1 , D.L. Cutajar 1 , A. Bece 2 , J. Bucci 2 , S. Alnaghy 1 , M. Favoino 3 , M. Tartaglia 3 , F. Carriero 3 , J. Jakubek 4 , S. Pospisil 4 , K. Loo 1 , M. Safavi- Naeini 1 , M. Lerch 1 , A.B. Rozenfeld 1 1 University of Wollongong, CMRP, Wollongong, Australia 2 St George Hospital, St George Cancer Care Centre, Kogarah, Australia 3 Advanced Computer System Pty Ltd, Research, Rome, Italy 4 Czech Technical University of Prague, Institute of Experimental and Applied Physics, Prague, Czech Republic Purpose or Objective BrachyView is a novel in-body imaging system developed with the objective to provide real-time intraoperative dosimetry for LDR prostate brachytherapy treatments. The system can reconstruct seed positions after

Figure 1: CT and BrachyView reconstructed seed discrepancies after co-registration, with average x, y and z errors