Determination of radiation dose from patients undergoing Tc-99m Sestamibi nuclear cardiac imaging

4th International Conference on Computational and Experimental Science and Engineering (ICCESEN) -- OCT 04-08, 2017 -- Kemer, TURKEY --To date, myocardial perfusion (MP) has been utilized to assess the adequacy of blood flow to the myocardium in order to determine the ischemic heart diseases. With the advent of SPECT/CT, MP became the most common investigation in the field of nuclear cardiology with more accuracy and details. Thallium-201 and Technetium-99m (Tc-99m) have been early used in cardiac nuclear imaging. Half-life of Tc-99m is 6 h, and its energy is 140 keV, while the half-life of Tl-201 is as longer as 73 h, its X-ray energies range between 69 and 81 kV in addition to gamma rays of 135 keV and 167 keV. The purpose of the present study was to explore the radiation dose rates emitted from the patients following Tc-99m sestamibi injection. To achieve that, the radiation emanated to the environment was measured at different distances from patients and various time intervals for 20 patients using GM counter. The mean radioactivity administered to the patients was 391.1 MBq (10.6 mCi), with a range between 276.8 MBq to maximum of 515.4 MBq. Radiation dose rate was found 9.07 mu Sv h(-1) at 1 m distance from the patient's chest level after 7.6 min, then decayed to 7.93 mu Sv h(-1) after 36.5 min, and 7.83 mu Sv h(-1) later to 66.4 min. It was concluded that 1 m distance from the patients sounds sensibly adequate to maintain the occupational dose within the safe limit following Tc-99m sestamibi injection, while verification of public dose rate <= 1 mu Sv h(-1) at 1 m distance from the patient prolongs to 14 h following Tc-99m injection.WOS:0004788945000382-s2.0-8506148905

Evaluation of renal function in low-dose cyclosporine-treated patients using technetium-99m diaminocyclohexane: a cationic tubular excretion agent

Technetium-99m diaminocyclohexane (DACH) is a new tubular agent excreted via a cationic transport mechanism, like cyclosporine-A (CsA), It is expected that Tc-99m-DACH will permit effective assessment of tubular function in CsA-treated patients. To establish the pharmacokinetic characteristics of Tc-99m-DACH and to ascertain whether this new agent is useful in CsA-treated patients, 11 healthy volunteers and 15 CsA-treated patients underwent renal imaging and clearance studies using Tc-99m-DACH and chromium-51 ethylene diamine tetra-acetic acid (EDTA). 99mTc-DACH yielded satisfactory dynamic renal images in all participants. The mean plasma clearance of Tc-99m-DACH was significantly greater than that of Cr-51-EDTA In volunteers (109.4+/-19.7 ml/min versus 86.6+/-13.7 ml/min, P<0.05). However, the urinary excretion of 99mTc-DACH at 90 min was significantly lower than that of Cr-51-EDTA (46.1%+/-9.3% versus 53.1%+/-8.6%, P<0.05), most probably due to its partial parenchymal retention. The elimination half-life of Tc-99m-DACH was significantly increased in CsA-treated patients in comparison to volunteers, and consequently the plasma clearance values were significantly suppressed in these patients, in contrast to Cr-51-EDTA and endogenous creatinine clearance values. In conclusion, our findings indicate that Tc-99m-DACH, as a sensitive marker of cationic tubular function, could be used to monitor renal haemodynamics in patients receiving CsA treatment

Comparison of 18F-fluorodeoxyglucose PET/CT findings with vascular endothelial growth factors and receptors in colorectal cancer

The purpose of this study was to evaluate the association of F-18-fluorodeoxyglucose (FDG)-PET/CT findings with the vascular endothelial growth factor (VEGF) family and its receptor (VEGFR) levels in metastatic and nonmetastatic colorectal cancer (CRC). Fluorine-18 FDG-PET/CT scans were performed for initial staging and restaging of patients with CRC. FDG-PET/CT findings of tumor (such as the presence of a primary tumor, the lymphatic or distance metastases, and the maximum standardized uptake value (SUVmax) of the primary tumor), serum VEGF A-C-D-E levels, and serum VEGF receptor 1-2-3 levels were analyzed. A total of 63 patients were included into the study (35 males, mean age 61.3 +/- 11.9 years). Patients were divided into two groups, based on positive and negative PET/CT findings. Patients were also categorized according to the presence of metastasis. All evaluated parameters were significantly higher in the PET/CT-positive group than the PET/CT-negative group (p < 0.001). All those parameters were also positively correlated with each other. The highest correlation for SUVmax of primary tumor was found with VEGFR-3 (p < 0.001, r = 0.665). Patients with metastases had high levels of VEGF-D, VEGF-A, VEGF-C, VEGF-E, and VEGFR-3 than those without metastases. These parameters had better specificity and sensitivity values than the SUVmax of the primary tumor for detection of metastases. However, VEGF-D was the best indicator of metastasis in all of those parameters (VEGF-D vs SUVmax; sensitivity 100 vs 100 %; specificity 76 vs 76 %; AUC 0.903 vs 0.835; p < 0.001, respectively). Vascular endothelial growth factor family and its receptors were significantly higher in metastatic CRC patients. VEGF-D was the best indicator of metastasis than all VEGF family, VEGFR-3, and primary tumor SUVmax. VEGF family (A-C-D-E) and VEGFR-3 may help to determine the prognosis and management of CRC