Three gamma annihilation using radioiodine-124 for PET hypoxia imaging: Pilot study

Hypoxic solid tumours have a poor prognosis and little curability when treated with radiation therapy. Consequently, evaluation of oxygen levels in solid tumours is required to increase the proportion of patients who experience treatment success. The three gamma annihilation of radioiodine −124 (¹²⁴I) during positron emission tomography (PET) can be used to diagnose hypoxia in solid tumours. ¹²⁴I is the focus of this study, which intends to evaluate its role in detecting hypoxia in samples with various oxygen concentrations. At King Faisal Specialist Hospital and Research Center (KFSH&RC) in Saudi Arabia, a system was set up to monitor the yield of the three gamma using High Purity Germanium (HPGe) radiation detectors. These detectors, operating under the same conditions as one another, were used to record the triple coincidence. 5.0 mL of water was treated with oxygen and nitrogen gases to produce oxygenated and deoxygenated samples. In measuring the relative three gamma to two gamma yield, the peak to valley and peak to peak methods were compared. The three gamma coincidence was increased by 23% in deoxygenated sample compared to oxygenated one. The results of this study illustrated that the three gamma detection was increased in deoxygenated samples (hypoxia).