[en] ¹³¹I is one of the most important radionuclides used in nuclear medicine. The accompanying isotope ¹²⁹I with insignificant activities in ¹³¹I-pharmaceuticals, produced in THOR, were determined in terms of ¹²⁹I/¹³¹I ratio by neutron activation analysis. The detection limit of ¹²⁹I can be lowered to order of 0.1 Bq, superior to conventional radiometric methods. The ¹²⁹I/¹³¹I ratios in the ¹³¹I-pharmaceuticals, were measured to be in the range from 3.9 to 8.3

[en] Addition of Mn(II) at 2.5 microM or higher to stationary-phase cultures of Deinococcus radiodurans IR was found to trigger at least three rounds of cell division. This Mn(II)-induced cell division (Mn-CD) did not occur when the culture was in the exponential or death phase. The Mn-CD effect produced daughter cells proportionally reduced in size, pigmentation, and radioresistance but proportionally increased in activity and amount of the oxygen toxicity defense enzymes superoxide dismutase and catalase. In addition, the concentration of an Mn-CD-induced protein was found to remain high throughout the entire Mn-CD phase. It was also found that an untreated culture exhibited a growth curve characterized by a very rapid exponential-stationary transition and that cells which had just reached the early stationary phase were synchronous. Our results suggest the presence of an Mn(II)-sensitive mechanism for controlling cell division. The Mn-CD effect appears to be specific to the cation Mn(II) and the radioresistant bacteria, deinococci

[en] Lipiodol has important diagnostic and therapeutic uses in hepatoma. However, the mechanisms of its selective, prolonged retention in hepatoma cells is not well understood. Therefore, using oil-red O, light and electron microscopy and neutron activation analysis we have determined that HepG2 cells are characterized by lipiodol deposition and emulsification on the cell surface, action uptake of lipodol by endocytosis, and prolonged intracellular retention. These findings may have major clinical significance in the development of a new treatment for hepatoma patients

[en] We measured the radiation damage and its recovery of undoped BGO crystals. A radiation dose of up to 2 Mrad makes the scintillation light output decrease by 20%, but recovers to 100% with a time constant of 1 h. A radiation dose of 10 Mrad makes the scintillation light output decrease by 30%, and recover to 90% with a time constant of 10 h

[en] We checked the performance of undoped BGO crystals under extremely high dose conditions (dosage up to 88 Mrad). The light outputs of the crystals drop by ∼30% after receiving 10 Mrad of γ-ray dose but remain stable throughout the rest of the test. The self-recovery behavior of BGO under 20 Mrad has also been studied. The reduced variation in light output from pre-radiated BGOs, together with a fixed recovery limit, indicate that a pre-radiation process may be helpful to stabilize the BGO performance in a low dose environment

[en] A refined method for the measurement of protein-bound iodine (PBI) in blood serum was demonstrated by the use of epithermal neutron activation analysis (ENAA). PBI in ammonium sulfate-precipitated serum protein, after epithermal neutron activation was determined by high resolution γ-ray spectrometry. From our results, the PBI concentration was 67.8 ± 2.2 ng/mL. Good agreement was obtained with published data, ranging from 40 to 80 ng/mL, which had been obtained using different analytical techniques. The validity of these techniques for PBI has been born out by a very good accuracy and simplicity without temperature dependence. (Author)

[en] A refined method for the measurement of protein-bound iodine (PBI) in blood serum was demonstrated by the use of epithermal neutron activation analysis (ENAA). PBI in ammonium sulfate-precipitated serum protein, after epithermal neutron activation, was determined by high resolution γ-ray spectrometry. From the authors' results, the PBI concentration was 67.8 ± 2.2 ng/mL. Good agreement was obtained with published data, ranging from 40 to 80 ng/mL, which had been obtained using different analytical techniques. The validity of these techniques for PBI has been borne out by a very good accuracy and simplicity without temperature dependence. (author)

[en] We check the scintillation light yield of all BGO crystals used for the Extreme Forward Calorimeter (EFC) at BELLE. The percentage spread of the distribution is only 6%. The nonuniformity of the light yields measured lengthwise for the forward EFC is close to 13% and is ∼0% for the backward EFC. The test crystals, two per ingot, from mass-production are subjected to the radiation hardness test. The results obtained at BINP and NTU are in good agreement. Some EFC crystals, selected randomly, show the light yields drop about 25-50% after receiving 1 krad dose and remain stable afterwards. There is little sensitivity to the rate that the 1 krad dose is received, since the recovery process is very slow, in the order of days to weeks

[en] In our research, a radioactive boron compound, B-I-131-lipiodol, that can be selectively retained in hepatoma cells was prepared. Combining the effect of α particles produced by boron neutron capture reaction with the β particles released by radionuclides in the radioactive boron compounds will produce a synergistic killing effect on cancer cells. Human hepatoma HepG2 cell cultures were used to examine the stability and the intracellular distribution of the radioactive boron drug. Microscopes were used to examine the interaction and retention of B-I-131-lipiodol globules in the individual hepatoma cell. Moreover, ICP-AES and NaI scintillation counter were performed to determine boron concentrations and I-131 radioactivity, respectively. Results showed that B-I-131-lipiodol with a boron concentration and a specific radioactivity ranged from 500-2000 ppm and 0.05-10 mCi/mL respectively was stably retained in serum. The radiochemical purity of B-I-131-lipiodol was 98%. After supplement with a medium containing B-I-131-lipiodol, the HepG2 cells had intracellular B-I-131-lipiodol globules in the cytoplasm as seen by inverted light microscope, the I-131 and boron can be stably retained in HepG2 cells. (author)

[en] Boron neutron capture therapy (BNCT) is a cancer treatment modality using a nuclear reactor and a boron compound drug. In Taiwan, Tsing Hua open-pool reactor (THOR) has been modulated for the basic research of BNCT for years. A new BNCT beam port was built in 2004 and used to prepare the first clinical trial in the near future. This work reports the microdosimetry study of the THOR BNCT beam by means of the tissue equivalent proportional counter (TEPC). Two self-fabricated TEPCs (the boron-doped versus the boron-free counter wall) were introduced. These dual TEPCs were applied to measure the lineal energy distributions in air and water phantom irradiated by the THOR BNCT mixed radiation field. Dose contributions from component radiations of different linear energy transfers (LETs) were analyzed. Applying a lineal energy dependent biological weighting function, r(y), to the total and individual lineal energy distributions, the effective relative biological effectiveness (RBE), neutron RBE, photon RBE, and boron capture RBE (BNC RBE) were all determined at various depths of the water phantom. Minimum and maximum values of the effective RBE were 1.68 and 2.93, respectively. The maximum effective RBE occurred at 2 cm depth in the phantom. The average neutron RBE, photon RBE, and BNC RBE values were 3.160±0.020, 1.018±0.001, and 1.570±0.270, respectively, for the THOR BNCT beam.