Permanent breast seed implant (PBSI) brachytherapy technique was recently introduced as an alternative to high dose
rate (HDR) brachytherapy and involves the permanent implantation of radioactive <sup>103</sup>Palladium seeds into the surgical
cavity of the breast for cancer treatment. To enable accurate seed implantation, this research introduces a gamma camera
based on a hybrid amorphous selenium detector and CMOS readout pixel architecture for real-time imaging of
<sup>103</sup>Palladium seeds during the PBSI procedure. A prototype chip was designed and fabricated in 0.18-μm n-well CMOS
process. We present the experimental results obtained from this integrated photon counting readout pixel.
Bone autografts are routinely employed in the reconstruction of facial deformities resulting from trauma, tumor ablation or congenital malformations. The combined use of post- operative 3D CT and SPECT imaging provides a means for quantitative in vivo evaluation of bone graft volume and osteoblastic activity. The specific objectives of this study were: (1) Determine the reliability and accuracy of interactive computer-assisted analysis of bone graft volumes based on 3D CT scans; (2) Determine the error in CT/SPECT multimodality image registration; (3) Determine the error in SPECT/SPECT image registration; and (4) Determine the reliability and accuracy of CT-guided SPECT uptake measurements in cranial bone grafts. Five human cadaver heads served as anthropomorphic models for all experiments. Four cranial defects were created in each specimen with inlay and onlay split skull bone grafts and reconstructed to skull and malar recipient sites. To acquire all images, each specimen was CT scanned and coated with Technetium doped paint. For purposes of validation, skulls were landmarked with 1/16-inch ball-bearings and Indium. This study provides a new technique relating anatomy and physiology for the analysis of cranial bone graft survival.
It is known that the human visual system has varying sensitivity to different spatial frequencies. We are attempting to develop a better understanding of the interaction between the target and surround in a visual detection task, by changing the properties of the surround in frequency space. In our experiments, a known target is superimposed on a bandwidth- limited Gaussian noise background. The size, brightness, and position of the target are kept constant. The experimental design is a `Signal Known Exactly' ROC experiment. For each background the observer knows that there is a 50% probability that the target is present. The observer is asked to state a confidence level from 1 to 5 that a target is present in a given background. Detection performance for backgrounds with different frequency content is compared using the area under the ROC curve. The results of these experiments indicate that performance varies markedly as the frequency content of the background is changed. Observer performance dropped to a minimum when the background frequency was close to the frequency of maximum contrast sensitivity of the human visual system.