In order to study the migration behavior of85Srunder discontinuous water-flow condition in a natural aerated zone, the migration experiments were carried out by a column method, in which deionized water was intermittently fed into a sandy soil layer traced with85Sr. The migration velocity of cationic85Srwas increased when the times of flow interruption increased. This was probably attributed to the decrease in the distribution coefficient of85Srwith increasing concentration ofCa2+which was eluted from the soil into interstitial water during the interrupted period. Values of the distribution coefficient were estimated from the concentration of coexistentCa2+in effluent. The reducing tendency for distribution coefficient with the interruption times agreed well between the estimated values and the values determined from the migration velocity of85Srin the soil layer.
In radioimmunotherapy, an algorithm is proposed for the purpose of calculating three-dimensional absorbed dose distributions of non-water equivalent tissues. The three-dimensional absorbed dose distribution due to the algorithm, is given by convolution of the threedimensional dose matrix for a unit cubic voxel containing unit cumulated activity, with the three-dimensional matrix of the cumulated activity distribution given by the same voxel size above. The three-dimensional dose matrix for the unit voxel source, is calculated from the β- or photon-dose point kernel in the corresponding tissue. Present work theoretically showed that β- and photon-dose point kernels in non-water equivalent tissue can be calculated by applying a scaling factor on distance to each dose point kernel in water. In consequence, present calculation algorithm is essentially the same as the algorithm for water that authors have already developed. Computer simulations were performed using the MIRD lung phantom, and the agreement obtained between the results of present work and the MIRD method, supported the validity of the proposed calculation algorithm.
First-pass radionuclide ventriculography (FRNV) followed by myocardial SPECT with99mTc-MIBI was performed on 9 patients with coronary artery disease at rest and ATP infusion. When99mTc-MIBI (740 MBq) was injected, FRNV was simultaneously performed and left ventricular function was evaluated. One hour after the injection of99mTc-MIBI, myocardial SPECT was performed. Agreements in findings with regard to the presence or absence of myocardial ischemia or infarction were 19 out of 27 (70%) segments. Left ventricular ejection fraction (LVEF) decreased (p<0.01) in the patients with multi vessel disease during ATP infusion. The wall motion abnormality during ATP infusion showed improvement after coronary bypass surgery (CABG) . Improvement of regional wall motion or LVEF (regional EF) may reflect post CABG improvement.
We investigated the performance of a low-energy (LE) collimator and a medium-energy (ME) collimator in201Tlradiopharmaceutical scintigraphic imaging contaminated with202Tlwhich emittes higher energy photons (440 keV) . Using these collimators, energy spectra, planar images and SPECT images were acquired for three201Tlradiopharmaceutical sources. From the result of the energy spectra measurement, the LE collimator had a large amount of septral penetration by the high energy photons from202Tl, compared with the ME collimator, but both collimators showed the almost same energy distribution at201HgX-ray energy region. In planar and SPECT imaging using single-energy window (W1 : 71 keV±15%), both collimators had the same contrast values for some cold lesions, but for dual-energy window (W1 plus W2 : 167 keV±10%) the ME collimator gave better contrast values than the LE one. In conclusion, the LE collimator is suitable for the single-energy window (W1) imaging and the use of the ME collimator is recommended for the dual-energy window (W1+W2) imaging.
The comparative study of the blood clearance tests of99mTc-Phytate (99mTc-P) and indocyanine green (ICG) was undertaken in liver-injured rats with α-naphthylisothiocyanate (ANIT) . The blood clearances of99mTc-P and ICG in rats decreased with the increase in dose of ANIT and with the time elapsed after ANIT administration. As compared with the blood clearance test of ICG, the blood clearance test of99mTc-P in rats was found to be more sensitive in detection of the hepatic dysfunction with mildly damaged stage, but to be equally accurate in detection of the hepatic dysfunction with severely damaged stage induced by ANIT.