e. saeedzadeh

One of the most significant and common methods for early detection of breast cancer in the world is lymphoscintigraphy. In clinical trials, [99mTc]Tc-phytate has shown remarkable results for the detection of metastatic axillary lymph nodes prior to surgery. It is expected that the introduction and development of an appropriate alternative radiopharmaceutical including 67Ga for lymphoscintigraphy will be an important deal in the clinic as the half-life of 67Ga is longer than that of 99mTc (78.25 hours versus 6 hours). Radiolabeling of phytic acid with 67Ga is conducted in this study. Based on radioactive thin layer chromatography (RTLC), the radiochemical purity (RCP) was estimated at >99%. The final product represented satisfactory stability under human serum conditions, which was calculated to be greater than 89% during 3 days of study. Pre-clinical studies confirmed the urinary system as the main excretion route for radiopharmaceuticals. A human estimation dosimetry study based on preclinical data was also presented.

While the conventional parallel-hole collimators are widely used in myocardial perfusion imaging (MPI) with SPECT, they are suboptimal in balancing the existing sensitivity-resolution compromise. Therefore, multi-pinhole collimation has been proposed to address the problem. In the present study, a channel multi-pinhole collimated SPECT scanner is modeled and then simulated using the GATE Monte Carlo simulation. The multi-pinhole collimator comprises eight apertures. The material, diameter, and height of the apertures were assumed to be varying. A comparison with conventional single-pinhole was also conducted. The results show that increasing the hole diameter leads to degraded spatial resolution for the multi-pinhole collimator. Compared to the single-pinhole, the multi-pinhole collimators suffer from projection overlapping and thus deteriorated spatial resolution. The findings confirm that the channel multi-pinhole collimators outperform the single-pinhole apertures by providing much higher sensitivity at the expense of slightly lower spatial resolution and therefore would be the collimator of choice for MPI with SPECT.

The present study intended to determine and report patient effective dose on the basis of patients and exposure data.

A nationwide computed tomography (CT) survey was provided as a report of patient doses in 2015-2016. Scan details were collected for nearly 2,000 adults and children in four age groups subjected to CT examinations. From total 565 CT scanners in different models in Iran, 120 different scanners were sampled. ImpactDose software was used to calculate the effective dose (ED) by collecting the necessary data also as an alternative fast method, the ED was estimated by multiplying dose length product (DLP) and a conversion factor.

There was a high variation in doses received by patients. The estimated EDs by the DLP and conversion factor were lower (except for sinus protocol) than those by ImpactDose software (p=0.014). The mean EDs were 1.09, 0.66, 7.70 and 13.29 mSv for adult patients’ procedures of head, sinus, chest and abdomen-pelvis, respectively. In terms of CTDIvol and DLP, in Iran the mean effective doses were significantly lower than other countries.

Publishing guidelines and exposure tables according to patient situations is necessary to decrease variations in doses and exposure parameters. Since the DLP conversion factor leads to a considerable discrepancy in calculating ED, when there is a need for precise dose calculations, the DLP conversion factor should not be used. Furthermore, it is suggested that ED be used as DRL, instead of CTDIvol.