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Nowadays, the irradiation of blood and blood products, as well as sterilization of pharmaceuticals and biological materials used in the medical industry, are being carried out in developed countries and some developing countries. Usually for this purpose, self-contained dry source storage irradiators containing cesium-137 or cobalt-60 gamma ray sources with activity up to 3 kCi are used as blood irradiator facilities. In this research, an attempt was made to use the MCNPX code to perform the calculations related to the nuclear design of a blood irradiator facility using cobalt-60 line sources in two parts of iso-dose curves and shielding according to internationally accepted standards. The dose uniformity ratio inside the irradiation chamber was about 2 and the external dose rate at a distance of 5 cm from the surface of the gamma cell device was about 36 µSv/h and below the allowable limit. The results showed that the iso-dose curves were completely symmetric and the delivered dose increased near the cobalt-60line sources while decreasing as the distance away from the line sources and closer to the cylindrical axis of the irradiation chamber. In addition, the results showed that the designed lead shield with an average thickness of 30 cm easily blocks the gamma rays and in terms of health physics, working with such a blood irradiator will not pose any risk of radiation to employees.

The single- and double-side dose distributions of 10 MeV electron beam irradiation were measured and extensively analyzed to optimize the irradiation process for medical and health care products. To this end, the optimal penetration depth and depth dose distribution curves of an electron beam were measured and analyzed in three uniform materials with varying densities: a PE board, Chevrolet board, and high-density high-pressure foam board. The results demonstrated that the dose uniformity ratio range of double-side irradiation was approximately 1.0–2.6. The maximum acceptable dose variation for medical and health care products should be a minimum of 2.6 times that of the minimum sterilization dose. A region on the depth curve of an electron beam dose could be selected according to the ratio between the maximum acceptable dose and the minimum sterilization dose; alternatively, the absorbed dose for health care products could be controlled by optimizing the packaging form to improve the irradiation mode and pretreatment of the product. This study demonstrated the importance of effective radiation sterilization for medical and health care products.

Irradiated star apples at the minimum absorbed dose of 400 Gy for phytosanitary purpose in Vietnam have been already approved to import to US. In this study, the fresh star apples were treated with electron beams at doses of 0.4, 0.6, 0.8 and 1.0 kGy to evaluate its effect on quality of fruits. The results showed that electron beam radiation doses of 0.4 kGy and 0.6 kGy did not affect to the surface color and percentage of weight loss of fruits. There was significant difference in overall acceptability score with the values of 3.95, 3.92 and 2.45 between irradiated fruits at 0.4, 0.6 kGy and the control (0 kGy) respectively after 6 days in storage at the ambient conditions (temperature of 26±1oC and humidity of 85-90%). Thus, dose range between 0.4 and 0.6 kGy should be used to extend the shelf life of star apple fruits. Because of the low penetration depth of electron beams onto products, dose uniformity ratio (DUR) in the standard carton box for packaging the star apple fruits as well as absorbed doses outside and inside of fruits were calculated.