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.

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.

Introduction: In vivo dosimetry verification is currently a necessity in radiotherapy centres in Europe countries as one of the tools for patient-specific QA, and now its demand is currently rising in developed countries, such as Malaysia. The aim of this study is to characterize commercial EPID-based dosimetry and its implementation for radiotherapy treatment verification in Malaysia. Materials and Methods: In this work, the sensitivity and performance of a commercially available in vivo dosimetry system, EPIgray® (DOSIsoft, Cachan, France), were qualitatively evaluated prior to its use at our centre. EPIgray response to dose linearity, field size, off-axis, position, and angle dependency tests were performed against TPS calculated dose for 6 MV and 10 MV photon beams. Relative deviations of the total dose were evaluated at isocentre and different depths in the water. EPIgray measured dose was validated by using IMRT and VMAT prostate plan. All calculation points were at the beam isocentre and at points suggested by TG-119 with accepted tolerance of ±10% dose threshold. Results: EPIgray reported good agreement for linearity, field size, off-axis, and position dependency with TPS dose, being within 5% tolerance for both energy ranges. The average deviation was less than ±2% and ±7% in 6 MV and 10 MV photon beams, respectively, for the angle dependency test. A clinical evaluation performed for the IMRT prostate plan gave average agreement within ±3% at the plan isocentre for both energies. While for the VMAT plan, 95% and 100% of all points created lie below ±5% for 6 MV and 10 MV photon beam energy, respectively. Conclusion: In summary, based on the results of preliminary characterization, EPID-based dosimetry is believed as an important tool and beneficial to be implemented for IMRT/VMAT plans verification in Malaysia, especially for in vivo verification, alongside existing pre-treatment verification.