Iodine-131 (I-131) mostly used in nuclear medicine for radioiodine ablation (RAI) therapy and hyperthyroid treatment. Patient was orally ingested I-131 and warded within 3 to 4 days for RAI therapy, whereas outpatient for hyperthyroid treatment. Radioactive waste from patient’s body such as urine and feces were eliminated from the ward into delay tank. Delay tank is an underground system to reduce radioactivity of contaminated I-131 clinical waste water at certain level before will be discharged into ordinary sewage system. Delay tank indirectly restricted the number of patient admission due to its periodical clearance and small volume size. Thus, a new technique to extract I-131 radionuclide with contaminated mixtures in solid form from the delay tank has been proposed as an alternative for clinical waste water management in nuclear medicine. Radioactive clinical waste water samples from delay tank were mixed with Graphene Oxide (GO) with varies in concentrations before filtered using micro pore filter paper. After 15 – 30 minutes, the radioactivity of the water residue left beneath the filter paper were counted using well counter. The measurements were repeated on fourth, eighth, twelfth and sixteenth days, which is significant to the natural decay of I-131 radionuclide. The water residue radioactivity decreases over the concentration of GO throughout the experiment. The mixtures of GO:I-131 (sediment formed on the filter paper) were analyzed using Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-rays (EDX) for morphology and elemental analysis. FESEM image revealed the maximum GO concentration produced high agglomeration morphology. EDX shows I-131 and other elements were attracted to GO layered sheets. The results showed that the GO had high sorption capacities in the removal of radionuclides, which was attributed to the large number of oxygen-containing functional groups on the surface or edge sites.

Advances in iterative image reconstruction enable absolute quantification of SPECT/CT studies by incorporating compensations for collimator-detector response, attenuation, and scatter. This study aimed to assess the quantitative accuracy of SPECT/CT based on different levels of 99m Tc activity (low/high) using different SUV metrics (SUV mean , SUV max , SUV 0.6 max , and SUV 0.75 max [the average values that include pixels greater than 60% and 75% of the SUV max in the volume of interest, respectively]). Methods: A Jaszczak phantom equipped with 6 fillable spheres was set up with low and high activity ratios of 1:4 and 1:10 (background-to-sphere) on background activities of 10 and 60 kBq/mL, respectively. The fixedsize volume of interest based on the diameter of each sphere was drawn on SPECT images using various metrics for SUV quantification purposes. Results: The convergence of activity concentration was dependent on the number of iterations and application of postfiltering. For the background-to-sphere ratio of 1:10 with a low background activity concentration, the SUV mean metric showed an underestimation of about 38% from the actual SUV, and SUV max exhibited an overestimation of about 24% for the largest sphere diameter. Meanwhile, bias reductions of as much as 26% and 27% for SUV 0.6 max and SUV 0.75 max , respectively, were observed. SUV max gave a more accurate reading than the others, although points that exceeded the actual value were detected. At 1:4 and 1:10 background activity of 10 kBq/mL, a low activity concentration attained a value close to the actual ratio. Use of 2 iterations and 10 subsets without postfiltering gave the most accurate values for reconstruction and the best image overall. Conclusion: SUV max is the best metric in a high-or low-contrast-ratio phantom with at least 2 iterations, 10 subsets, and no postfiltering.

This paper reports the ability of graphene oxide (GO) as a radionuclide adsorbent material for an alternative approach in nuclear medicine radioactive waste management. Notable physicochemical properties of GO mainly consist of oxygen-containing functional groups on its basal plane and edges site in the form of epoxy, hydroxyl, and carboxyl groups, making it a promising candidate for radionuclide extraction material from aqueous solution. Herein, GO was synthesised via a simplified Hummers method. The radioactive clinical waste, which is urine, was collected right after the scanning procedure and mixed with GO in various concentrations: 1 mg/ml, 1.5 mg/ml, 2 mg/ml, 2.5 mg/ml, and 3 mg/ml. The mixture was then filtered using micropore filter paper, leaving sediments on the filter paper and wastewater residues. The radioactivity of sediment and water residue was determined by using a well counter after 3, 6, 9, and 12 hours of filtration process. The activities of the sediment and water residues were found to be decreased with increasing GO concentrations. The FESEM image revealed high agglomeration structure when the sample was treated with GO of 3 mg/ml concentration. Further analysis via EDX showed the presence of other elements in the urine, which led to its attraction to the GO-layered sheets. This analysis also confirmed the presence of oxygen-functioning group in GO that facilitated the agglomeration process and solidified the radionuclide waste.