ABSTRACT
Background: in this study, human absorbed dose of a newly introduced bone imaging agent, 68Ga-[4-[[[bis[phosphonomethyl]]carbamoyl]methyl]-7,10-bis [carboxymethyl]-1,4,7,10-tetraazacyclododec-1-yl] acetic acid [68Ga-BPAMD], was estimated based on the rats data
Materials and Methods: 68Ga was obtained from the 68Ge/68Ga generator and it's radionuclidic and radiochemical purities were investigated. 68Ga-BPAMD complex was prepared at optimal conditions and the radiochemical purity was studied using instant thin layer chromatography [ITLC] method. The final preparation was injected to the normal rats and the biodistribution of the complex was followed up to 120 min post injection. The accumulated activity for animal organs was calculated. Finally, the human absorbed dose of the complexes was estimated by RADAR Method
Results: 68Ga-BPAMD complex was prepared in high radiochemical purity [>99%, ITLC] at optimal conditions. The biodistribution of the complex demonstrated that the main remained radioactivity would considerably accumulate into the bones. The results showed the highest amounts of absorbed dose on the bone surface [0.253 mGy/MBq] and in the bone marrow [0.250 mGy/MBq], while the other organs would receive an insignificant absorbed dose after injection of the 68Ga-BPAMD complex
Conclusion: the comparison of dosimetric results for 68Ga-BPAMD with other complexes shows this complex is a safer agent for bone scanning. This property as well as other characteristics such as the high resolution images of the positron emission tomography [PET] scanning and the availability of 68Ga in the form of 68Ge/68Ga generator, make this complex as a suitable agent for PET bone imaging
ABSTRACT
In megavoltage radiotherapy rooms, ordinary concrete is usually used due to its low construction costs, although higher density concrete are sometimes used, as well. The use of high-density concrete decreases the required thickness of the concrete barrier; hence, its disadvantage is its high cost. In a nuclear reactor, neutron radiation is the most difficult to shield. A method for production of economic high-density concrete with appropriate engineering properties would be very useful. Galena [PbS] mineral was used to produce of a high-density concrete. Galena can be found in many parts of Iran. Two types of concrete mixes were produced. The water-to-concrete [w/c] ratios of the reference and galena concrete mixes were 0.53 and 0.25, respectively. To measure the gamma radiation attenuation of Galena concrete samples, they were exposed to a narrow beam of gamma rays emitted from a cobalt-60 therapy unit. The Galena mineral used in this study had a density of 7400 kg/m[3]. The concrete samples had a density of 4800 kg/m[3]. The measured half value layer thickness of the Galena concrete samples for cobalt- 60 gamma rays was much less than that of ordinary concrete [2.6 cm compared to 6.0 cm]. Furthermore, the galena concrete samples had significantly higher compressive strength [500 kg/cm[2] compared to 300 kg/cm[2]]. The Galena concrete samples made in our laboratories had showed good shielding/engineering properties in comparison with all samples made by using high-density materials other than depleted uranium. Based on the preliminary results, Galena concrete is maybe a suitable option where high-density concrete is required in megavoltage radiotherapy rooms as well as nuclear reactors