A new clock distribution network using CMOS Single-Photon avalanche diodes (SPAD) in combination with free space optics is proposed. The system can work without special implementation of optical waveguides. It consists of an optical source with 660 MHz operation, which in the receiver end is composed of three parallel SPADs biased in quench, hold-off and recharge phases. With the pipeline analogues implementation of SPADs and a logic cell output a 660 MHz clock source can be achieved. The proposed system is post layout simulated in 180nm CMOS technology. The power consumption of 6. 74 mW for each SPAD cell, electrical jitter of 237 fs and skew of 43 ps is resulted.

Aims and background: In three dimensional conformal radiotherapy (3DCRT), treatment planning is based on computerized tomography (CT) images. However, the data obtained from CT may not be sufficient in target delination. The purpose of this study is to show the differences between the radiotherapy (RT) plans which were done with positron Emission tomography (PET) fusion or not. Methods: Patients with lung cancer between February 2009 and January 2012 at our institution were assessed retrospectively. Sixty patients who were treated with 3DCRT, CT simulation images were registrated with PET images. For each patient target volumes were determined and normal tissues were revised. Wilcoxon Signed Rank Test was used to compare the two groups. Results: For gross tumor volume (GTV), clinical target volume (CTV) and planning target volume (PTV); median volume values, median mean dose values and median maximum dose values were significantly different according to use of PET. About normal tissue doses; mean lung dose (MLD), lung V20, mean and maximum esophagus dose, V50 and V60, mean heart dose and maximum medulla spinalis dose were analyzed. Conclusion: Within these parameters there were statistically significant difference except in maximum dose of esophagus and V60. In our study, we observed decreased target volumes and higher dose distrubutions for target volumes in PET registrated RT plans. According to these data, it is possible to say that optimal RT plans can be formed for lung cancer by using PET registration.

In Single Photon Emission Computed Tomography (SPECT), collimator selection, optimization, and also geometric calibration have a major impact on the acquired image quality and also on an accurate detectability and diagnosis. The collimator optimization phenomena consider some parameters such as field of view, resolution, sensitivity, resolution at depth, septal thickness and penetration for a specific application task. While the parallel hole collimator is usually used in SPECT and planar imaging but due to the limited solid angle covered by the collimator, the system sensitivity and resolution were highly reduced. Meanwhile, other types of collimators such as pin-hole, multi-pin-hole, slant and slit-slat collimators were introduced with a trade-off between sensitivity and resolution. This article reviews improvements on collimators also by considering the geometry and geometric calibration methods for improving the image quality in single photon Emission Computed tomography.

Anosmia following head trauma is relatively common and in many cases is persistent and irreversible. The ability to objectively measure such a decline in smelling, for both clinical and medicolegal goals, is very important. The aim of this study was to find results of brain Single Photon Emission Computed Tomography (SPECT) in anosmic subjects after closed head trauma. This case-control cross sectional study was conducted in a tertiary referral University Hospital. The brain perfusion state of nineteen anosmic patients and thirteen normal controls was evaluated by means of the SPECT with 99mtc- ECD infusionbefore and after olfactory stimulation. The orbitofiontal lobe of the brain was assumed as the region of interest and changes in perfusion of this area before and after the stimulations were compared in two groups. The mean of brain perfusion in controls before and after the stimulation was 8.26% 0±19% and 9.89%± 0.54%, respectively (P<0.0001). Among patients group, these quantities were 7.97%±1.05% and 8.49%± 1.5%, respectively (P<0.004). The difference between all the measures in cases and controls were statistically significant (P<0.0001). There were no differences in age and sex between two groups. The brain SPECT is an objective technique suitable for evaluating anosmia following the head trauma and it may be used with other diagnostic modalities.

A 65-year-old man presented with intermittent abdominal pain for three months. Abdominal ultrasonography revealed a mass in the body of the pancreas. Moreover, abdominal contrast-enhancing Computed tomography revealed a homogenously enhancing mass in the body of the pancreas. Scan findings were in favor of the neuroendocrine tumor, and the serum chromogranin level was slightly raised (111. 9 ng/ml, normal <98). He had no history of vomiting, jaundice, melena, hematemesis, constipation, diarrhea, weight gain, weight loss, loss of appetite, and fever. He also had no symptoms related to the excessive production of catecholamines, such as hypertension. The patient was referred for Ga-68 DOTANOC positron Emission tomography-Computed tomography (Ga-68 DOTANOC PET-CT) for further evaluation. The scan was done to rule out metastatic disease or other synchronous lesions to plan surgical excision. The Ga-68 DOTANOC PET-CT revealed a pancreatic lesion with no other abdominal lesions. We noted multiple tracer avid soft tissue lesions on both sides of the neck that were not diagnosed previously. This case report demonstrates a rare case with multiple paragangliomas diagnosed by the Ga-68 DOTANOC PET-CT. This finding could lead to changes in patient management.

The use of Positron Emission Tomography (PET) with Computed Tomography (PET/CT) is rapidly expanding in childhood cancers including brain tumors, lymphomas, soft tissue tumors, and bone tumors such as osteosarcoma and Ewing sarcoma, thyroid cancers and rare tumors. Clinical applications of PET/CT in children with brain tumors include: to evaluate for recurrent tumor, to differentiate between recurrent tumor and post-treatment necrosis, to localize the areas of high grade disease in order to guide biopsy and treatment planning. Clinical applications of PET/CT in children with lymphomas include: initial staging of patients to determine the extent of disease, to determine response to chemotherapy or radiation therapy, post-chemotherapy assessment for patients with advanced stage of aggressive non-Hodgkin′s lymphoma, and Hodgkin′s lymphoma with residual CT abnormalities or initial bulky disease, to plan the duration of chemotherapy for patients with Hodgkin′s and non-Hodgkin′s lymphoma, and to plan the duration and the type of treatment for limited stage of aggressive lymphoma. FDG uptake is generally greater in higher grade than lower grade lymphomas. FDG-PET reveals disease sites that are not detected by conventional staging methods, resulting in upstaging of disease with potential therapeutic review.FDG-PET is useful for assessing the need for bone marrow biopsy, and residual or recurrent soft tissue masses seen on CT after therapy. Clinical applications of PET/CT in children with sarcomas include: to evaluate the primary soft tissue mass prior to biopsy to identify high grade areas and to guide biopsy, for staging of locally advanced high grade soft tissue sarcomas, for detecting of suspected local recurrence of soft tissue sarcoma after definitive treatment, for staging of Ewing′s sarcoma, and for initial staging and evaluation of potential recurrence in osteosarcoma. Clinical applications of PET/CT in children with neuroblastomainclude: evaluation of the extent of viable tumor tissue in primary tumor, staging and disease evaluation of MIBG-negative tumors, evaluation of residual mass or primary site for recurrent or residual tumor at post-treatment stage particularly if conventional studies are not helpful or equivocal, as well as evaluation for local recurrence or distant metastases at post-treatment stage or marrow transplantation. [11C]-Hydroxyephedrine ([11C]-HED), an analogue of norepinephrine, and [11C]-epinephrine PET have also been used in evaluating neuroblastoma. Uptake of these tracers is demonstrated within minutes after tracer administration, an advantage over MIBG imaging. In osteosarcoma and Ewing’s sarcoma, FDG-PET may play an important role in monitoring response to therapy. Another diagnostic role may be in assessing patients with suspected metastatic disease. Clinical applications of PET/CT in children with thyroid cancers include: detection and localization of suspected recurrence after definitive therapy in patients with elevated thyroglobulin levels and negative radioiodine scan (papillary and follicular carcinomas). Thyroid “incidentalomas” found on 18 FDG scanning appear to have a high rate of malignancy and should be assessed by fine-needle aspiration. Clinical applications of PET/CT in children with rare tumors include: monitoring hepatoblastomas during and after therapy by FDG-PET.

Introduction: In Single Photon Emission Computed Tomography (SPECT), the projection data used for image reconstruction are distorted by several factors, including attenuation and scattering of gamma rays, collimator structure, data acquisition method, organ motion, and washout of radiopharmaceuticals. All these make reconstruction of a quantitative SPECT image very difficult. Simulation of a SPECT system is a convenient method to assess the impact of these factors on the image quality.Materials and Methods: The SIMIND Monte Carlo program was employed to simulate a Siemens E.CAM SPECT system. Verification of the simulation was performed by comparing the performance parameters of the system. The verified system was used for SPECT simulations of homogenous and inhomogeneous voxelized phantoms in conjugation with hardware modifications. The resulting data were compared with those obtained from the simulated system without any modifications. Image quality was assessed by comparing the Structural SIMularity index (SSIM), contrast, and resolution of images.Results: The energy spectra acquired from both simulated and real SPECT systems demonstrated similar energy peak regions. The resulting full-widths-at-half-maximums were 13.92 keV for the simulation and 13.58 keV for experimental data, corresponding to energy resolutions of 9.95% and 9.61 %, and with calculated sensitivities of 85.39 and 85.11 cps/MBq, respectively. Better performance parameters were obtained with a hardware-modified system constructed using a 0.944 cm thickness NaI (TI) crystal covered by a layer of 0.24 cm aluminum, a slat of 4.5 cm Pyrex as a backscattering medium, and a parallel hole collimator of Pb-Sb alloy with 2.405 cm thickness.Conclusion: The modeling of a Siemens E.CAM SPECT system was performed with the SIMIND Monte Carlo code. Results obtained with the code are in good agreement with experimental results. The findings demonstrate that the proposed hardware modifications in the system appear to be suitable for further improvement of the performance parameters of the system, indicating that future investigations can be conducted on using the system for supplementary studies on image improvement in the field of nuclear medicine.

Background: Single photon Emission Computed tomography (SPECT) imaging is widely implemented in nuclear medicine for detecting coronary artery diseases. To increase the accuracy of the diagnosis, it is necessary to improve the quality of the SPECT images that can be degraded by noise. The aim of this study was to evaluate the effectiveness of using different filters such as Butterworth, Gaussian, Wiener with kernel sizes 3×3 and 5×5, and Median Modified Wiener Filters (MMWF with kernel sizes 3×3 and 5×5 to improve the quality of myocardial perfusion SPECT images with 99mTc-MIBI. Methods: A Siemens Symbia T2 dual head SPECT/CT scanner equipped with a low-energy and high-resolution collimator (LEHR) was used for collecting data for this cross-sectional-applied study. The noise ratio (SNR), peak to noise ratio (PSNR) and contrast to noise ratio (CNR) were the indices used to asses the quality of the myocardial perfusion SPECT images of 30 patients after the filters mentioned above have been applied to the images. Findings: Wiener filter with kernel size of 5×5 4. 90 ±,0. 69 and 2. 65 ±,0. 57 were found be the highest SNR and CNR indices respectively. However, it had the lowest PSNR in the range of 29. 93 ±,3. 13 (dB). In addition, the highest PSNR values were associated with the Gaussian filter as 50. 09 ±,10. 63 (dB). Conclusion: The results of this study show that the wiener filter of kernel size of 5×5 outperformed the others to improve the quality of myocardial perfusion SPECT images used in this study.