Radiation doses from 51Cr-bleomycin.

Extensive studies were made of long-term whole-body retention, plasma concentration, urinary excretion and organ retention of 51Cr in rats after intravenous injection of 51Cr-bleomycin. A similar but less extensive investigation was performed on rabbits, and whole-body retention, plasma concentration and urinary excretion was also followed in patients given 51Cr-bleomycin for diagnostic purposes. From an analysis of the collected information it followed that integrated whole-body and organ retention, corrected for radioactive decay, is similar in man and rabbit, and higher by a factor of about 2 in the rat. Doses to organs and whole body in man were calculated using the MIRD methodology and assuming conservatively that the kinetic data derived in rats are applicable to man. The organ and whole-body MIRD doses after 51Cr-bleomycin administration are comparable to those after 67Ga-citrate and the effective dose equivalent from a diagnostic amount of 740 MBq of the 51Cr complex amounts to about 6 mSv. However, the subcellular distribution in the liver of 51Cr, administered in the form of 51Cr-bleomycin, indicated a significant enrichment of 51Cr in the nuclei and in the DNA over mean concentrations in the liver cells. Also, the quality factor for Auger electrons, emitted by 51Cr, when assessed on the basis of the Q vs. LET relationship, as proposed by ICRP, was substantially higher than unity. Doses calculated for cell nuclei and the DNA in the liver cells were higher than the cell-averaged values by a factor 2.5 and 5, respectively, and the corresponding dose equivalents by a factor of 9 and 24. The effective dose equivalent, estimated on the basis of dose equivalents to cell nuclei and the DNA, amounted to 33 and 83 mSv per examination (740 MBq of 51Cr-bleomycin), respectively.

Comparative evaluation of renoscintigraphic properties and plasma clearance of 99MTc-DADS (99mTc-N,N'-bis/mercaptoacetamido ethylenediamine), 99mTc-DTPA and 131I-o-hippuran.

Plasma clearance of 99mTc-N,N'-bis (1,2-mercaptoacetamido) ethylenediamine (DADS), 99mTc-DTPA and 131I-o-hippuran (OIH) was determined in rabbits from blood-concentration decay curves after single i.v. injection of the compounds. Dynamic scintigraphy was performed using the same three compounds, and "activity" curves were compared as observed over kidney ROIs. Both clearance values and renoscintigraphic curves were similar for 99mTc-DADS and 99mTc-DTPA but evidently different from those of OIH. Biliary excretion of 99mTc-DADS was also observed. It appears that, in contrast to other authors, 99mTc-DADS cannot serve as a substitute for 131I-o-hippuran.

Direct assessment of effective renal plasma flow from renoscintigraphy with a gamma camera and an on-line computer.

A concept of a kidney uptake coefficient (UC) of 131I-o-hippurate was developed by analogy from the corresponding kidney clearance of blood plasma in the early period after injection of the hippurate. The UC for each kidney was defined as the count-rate over its ROI at a time shorter than the peak in the renoscintigraphic curve divided by the integral of the count-rate curve over the "blood"-ROI. A procedure for normalization of both curves against each other was also developed. The total kidney clearance of the hippurate was determined from the function of plasma activity concentration vs. time after a single injection; the determinations were made at 5, 10, 15, 20, 30, 45, 60, 75 and 90 min after intravenous administration of 131I-o-hippurate and the best-fit curve was obtained by means of the least-square method. When the UC was related to the absolute value of the clearance a positive linear correlation was found (r = 0.922, p greater than 0.99). Using this regression equation the clearance could be estimated in reverse from the uptake coefficient calculated solely on the basis of the renoscintigraphic curves without blood sampling. The errors of the estimate are compatible with the requirement of a fast appraisal of renal function for purpose of clinical diagnosis.

An attempt to use the Tc-99m-thiodisuccinic acid (TDSA) complex in renoscintigraphy. II. In vivo studies.

In the study the usefulness of Tc-99m-TDSA complex for renoscintigraphy was investigated. The results suggest that the complex undergoes elimination primarily via glomerular filtration similarly to Cr-51-EDTA and Tc-99-DTPA. Respective renoscintigraphic curves were obtained.

Oviduct patency control by means of 133Xe-solution.

The authors describe a radioisotopic method for the oviduct patency control in patients suffering from primary or secondary sterility. The application of 133Xe causes at least about 3-4 times less radiation than hysterosalpingographical tests. Ease of interpretation facility, painlessness and comparability of the results were noticed.