Recently the new method of γ-ray imaging by holography has been studied at several nuclear medical laboratories. This holography is very simple type; On axis Fresnel zone plate made by lead (2 mm thickness) is placed between γ-ray source and a detector, and its shadow is recorded as a hologram. The hologram obtained is illuminated by parallel beam of He-Ne laser (6328 Å), and image of radioisotope distribution in the object is reconstructed by diffraction. The better the resolution of the shadow hologram, the better reconstructed images are obtained. So that the detector recording γ-ray hologram must be selected seriously. In this paper, three kinds of medical X-ray film were used as the detector of hologram to compare film sensitivity. Generally these medical X-ray films have poor sensitivity for γ-rays of99mTc. In order to intensify the, film sensitivityy for γ-rays of99mTc, combinations with six kinds of intensifying screens were studied. In result, good film sensitivity was obtained by RP (Kodak Co.) film combinating with KZ-S fluorescent intensifying screen. The fluorescent screen was better than fluorometallic screens with similar properties. Using this film-screen combination, shadow holograms could be recorded for 2-3 minutes and images could be optically reconstructed.
The thyroid scanning with99mTc-pertechnetate has been widely used to the morphological examination of the thyroid, especially of the thyroid nodule, as first choice, because of marked reduction in the radiation exposure to the thyroid and less time consumption than131I-iodide. Twenty-two patients who was scanned with both of99mTc-pertechnetate (1 mCi to 2 mCi administered) and131I-iodide (100 μCi to 200 μCi administered) within one month from January, 1974 to January, 1975 have been presented here. The followings have resulted: 1) Thyroid scanning with 131I-iodide is better in eighty-three percents of patients with low twenty-four hour131I-uptake. 2) Both of99mTc-scan and131I-scan is equal in the scanning value in hyperthyroidism. 3) 99mTc-scan is more variable in the scanning quality than131I-scan. 4) 131I-scan may be excellent to the early post-operative menagement of thyroid cancer, in the visualization of the remnant thyroid and metastatic lymphnodes in the neck. It has not been discussed in the relation with the administered dosages of the radioiodide that the previous reports were different in the estimation of99mTc-scan and131I-scan in the hypothroidism. For the thyroid scanning with the diagnostic value is possible with both of the RAIU and the administered dosage of the radioiodide. Our result of131I better in the low RAIU may be attributable to 100μCi to 200μCi of the administered radioiodide.
Usefullness of Quantisorb, measuring total serum thyroxine, was evaluated in 67 subjects with or without thyroid abnormalities and pregnant women. Intraassay and interassay reproducibility was satisfactory; CV were ±3.8% and ±3.9% respectively. Preincubation time had no significant effects on Quantisorb values. In normal subjects, Quantisorb values were 8.8±0.7 μg/dl with rare overlap with those of hyperthyroid sera and overlap with those of hypothyroid sera in half cases. Quantisorb values showed good correlation with Triosorb values and Tetrasorb values with the exception of the pregnant cases, which revealed lower Triosorb values and higher Tetrasorb values. Both values (Quantisorb and Tetrasorb), however, were not always consistent. A good correlation was observed between Quantisorb values and T7 values (r=+0.94, p<0.001) in pregnant women as well as in the subjects with abnormal thyroid function and in the normal. Quantisorb test is characterized that it does not require the extraction of thyroxine and that the values are not affected by TBG levels and that only 0.1 ml of serum is necessary in the measurement. It might be one of the valuable tests for thyroid function.
Usefullness of Triosorb M test, measuring thyroid function indirectly, was evaluated in 82 subjects with or without thyroid abnormalities and pregnant women. A satisfactory reproducibility was obtained in intraassay and interassay; C. V. were ±1.71% and ±2.44% respectively. Triosorb M values were affected by the changes of incubation time and temperature, especially by the latter. Triosorb M values dropped significantly of hyperthyroid sera as incubation temperature rose, while values rose slightly of hypothyroid sera. Incubation time had almost the same effects on hyper-and hypothyroid sera values. A good correlation was observed between Triosorb M values and Triosorb values, incubated at 20°C or 25°C for 20 min. Incubated at 25°C, Triosorb M values were lower than those of Triosorb test of the same hyperthyroid sera. Incubated at 20°C, both tests showed very similar values each other of hyperthyroid sera as well as hypothyoid and normal sera. In normal subjects, Triosorb M values were 27.9±2.3% with rare overlap with those of hyperthyroid and moderate overlap with those of hypothyroid. Triosorb M test requires only 0.5 ml of serum and can be carried on in a short time with strict controlling the incubation temperature and time, and might be one of the usefull examinations of thyroid function.
Conventional HTSH radioimmunoassay kits requires long incubation time (four days for first incubation and one day for second incubation at low temperature) . This long incubation time is thought to reduce the clinical applicability of the HTSH radioimmunoassay kits. Recently rapid processing procedure of the kits is suggested by the manufacturer (two days method, Daiichi Radioisotopes Co., Ltd.) . The authors also tried to develop rapid processing procedure of the HTSH radioimmunoassay kits and performed basic study of the procedure. Bound percent of the zero samples decreased exponentially according to the increase in first incubation volume (0.2-0.7 ml) . This decrease in bound percent was larger in low standard HTSH concentration than in high standard HTSH concentration. Bound percent of the standard HTSH tubes differed little when first incubation temperature was changed from 20 to 30°C for 24 hours incubation, and it was considered that one could choose any temperature between 20 and 30°C in the first incubation for 24 hours. When sample HTSH concentration was expected to be low, especially under 5μU/ml, higher incubation temperature was thought to be desirable. In the second incubation, bound percent of zero samples and samples of high, middle and low HTSH concentration differed little between incubation period of three hours and seven hours at 25°C. Bound percent of zero samples differed little between incubation temperature of 4 and 10°C for 24 hours. Addition of HTSH free serum (carrier serum) to the standard HTSH tubes was necessary to correct the effect of nonspecific binding of HTSH-125I to the protein. This was especially important in assay of low (under 10μU/ml) HTSH samples. From these results, rapid processing procedure of HTSH radioimmunoassay kits should be as follows: (1) First incubation volume should be 0.4 ml. (2) First incubation temperature could be chosen any points between 20 and 30°C for incubation period of 24±4 hours. (3) Second incubation temperature and period after addition of second antibody could be chosen from each one of the followings; (a) at 25°C for 5±2 hours (two days method when combined with first incubation at 25°C for 20 hours), (b) at 4°C for 24 hours (three days method) . (4) Centrifuge at 3000 rpm for 30 minutes immediately after addition of 0.5 ml of phosphate buffer. Both of the above two rapid processing procedures revealed satisfactory reproducibility and recovery rates.
For the purpose to examine the sensitivities of Limulus test and inhibitory factors in the radiopharmaceuticals, the following procedures were employed. 1) Twenty radiopharmaceuticals commonly used were examined by Limulus lysate (Pre-gel) . 2) In order to detect the inhibitory factors, several doses of endotoxin (E. coli) were added to the radiopharmaceuticals before Limulus test and the results were compared with control study using saline solution of endotoxin. 3) When the pH of the reaction solution lay out of a suitable range (6.0-7.5), pH was adjusted by Tris-HCl buffer before reaction. As the result, 1) The sensitivity of control Limulus test using Pre-gel was positive at the concentration of 10-3μg/ml of endotoxin. 2) Limulus test could be applied with its sensitivity and without inhibitory reactions on99mTcO4-, 99mTc-albumin, 99mTc-MAA, 99mTc-Sn-colloid, 131I-hippurate, Na131I, Na251CrO4, 67Ga-citrate and57Co-bleomycin as they were supplied. 3) 111In-DTPA, 99mTc-phytate, 99mTc-pyrophosphate, 99mTc-DTPA, 131I-PVP, 59FeCl3, Na-phosphate (32P), 198Au-colloid and75Se-selenomethionine needed to be adjusted their pH to avoid inhibition. 4) Benzyl alcohol in the radiopharmaceutical showed inhibitory effect at the concentration more than 1%. Commonly used169Yb-DTPA was found to be evaluated by this test with the sensitivity of 2.5×10-3μg/ml due to addition of little amount of benzyl alcohol. 5) 131I-BSP showed intense inhibition on gelation reaction. 6) Contaminations of endotoxin were detected in99mTc-albumin, 99mTc-Sn-colloid, 131I-hippurate, Na131I, Na251CrO4, 198Au-colloid, 57Co-bleomycin and75Se-selenomethionine.