The determination of natural radioactive nuclides was carried out for 7 travertine samples collected from Tamagawa hot spring by means of the non-distructive γ-ray spectrometry and of the α-ray spectrometry. From the former measurements, the relative activity strength, due to228Ra, 226Ra, and228Th, and their ratios was obtained in comparison with the photopeak strength due to respective daughters, 228Ac, 214Bi, and212Pb, and with the results from a monazite sand standard. One travertine sample was engaged to the α-ray spectrometric determination of Th isotopes after the chemical purification using a234Th-yield tracer. On the basis of the resultant absolute content of228Th, the228Ra and228Th contents in the remainder samples were evaluated to be the range of 3-80 Bq (81-2160pCi) /g and 2-20Bq (54-540pCi) /g, respectively. These radioactive nuclides were verified to exist almost within a Hokutolite small crystals up to 90% and there are apparently the radioactive disequilibrium relations between228Ra and228Th among freshly deposited travertines. The presence of227Ac in Hokutolite was also suggested from the detection of227Th owing to 215Po-αpeak.
Serum ferritin level was evaluated as a marker for estimating the effect of the radiotherapy. The ferritin level was determined by a radioimmunoassay (SPAC ferritin kit) in sera obtained serially from 37 patients with various malignant neoplasma before and after radiotherapy. The changes in the ferritin level were investigated in comparison with various clinical findings. The decision for significant changes in the ferritin level was made by the sensitivity which is a diff erence value necessary to discriminate 2 values at confidence level of 95%. Out of 11 cases with clinical evidence of distant metastasis, the ferritin level was decreased in only one case (9%) and increased or unchanged in the rest. On the other hand, out of 26 cases without evidence of metastasis it was decreased in 9 cases (35%) and unchanged in 12 cases (46%) . The ferritin level was either decreased (64%) or unchanged (36%) in all the 11 cases with operation prior to radiotherapy, while out of 26 cases without operation (inoperable) it was decreased in only 3 cases (12%) . In all 5 cases with radiosensitive tumors as judged by tumor size, the ferritin level was either decreased (40%) or unchanged (60%) . Out of 28 cases with radioresistant tumors it was decreased in only 4 cases (14%) . All of these results indicated that serial measurements of the ferritin level is usefull for estimating the therapeutic effectiveness in radiotherapy.
Both conventional67Ga scintigraphy and67Ga emission computed tomography (ECT) were performed in 36 patients with bronchogenic carcinoma to evaluate clinical significance of67Ga-ECT as an adjunctive method. Each patient received 111-185MBq (3-5mCi) of67Ga-citrate intravenously. A rotation γcamera (Shimadzu LFOV-E) was used for ECT study, and a γ camera (Searle LFOV) was used for conventional scintigraphy. The detectability of 67Ga scintigraphy with ECT in primary tumors and regional lymph node metastases was compared retrospectively with that of conventional67Ga scintigraphy alone. There was little improvement in detection of primary and metastatic lesions by adding67Ga-ECT. Only 3 primary tumors were demonstrated more distinctly by67Ga-ECT. However, there was no lesion which was detected only by67Ga-ECT. Our data indicate that inclusion of67Ga-ECT in the routine examination is unnecessary in cases with bronchogenic carcinoma.
125I-labeled gastrin with high immunological activity and high specific radioactivity of 22.2-25.9 GBq (600-700mCi) /mg (0.5 iodine atom/1 gastrin molecule) was prepared by chloramine-T method using the amount of 100 molar ratio of chloramine-T to gastrin. As results of gastrin radioimmunoassay with polyethylene glycol (PEG) method, intra-and interassay coefficient of variation (C. V.) were 3.6-7.6% and 5.7-10.4%, respectively. The average recoveries of 2 levels of gastrin added to serum samples were 104±11.9% and 105±9.7%. The correlation coefficient of gastrin values obtained with dextrancoated charcoal (DCC) method and present method was γ=0.973. Antibody used in this study have a characteristic to strongly recognize the tyrosin residue at 12 position and the methionyl residue at 15 position on gastrin (1-17) .