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To determine the baseline incidence, prevalence, and characteristics of thyroid nodules in the population living around the Chernobyl nuclear power plant and to compare the findings with unexposed populations.Prevalence study. Population samples from seven highly contaminated villages were compared with six nearby control villages of the same size and type. The data were obtained as part of the International Chernobyl Project conducted in 1990.The study was conducted 4.5 years after the Chernobyl reactor accident that released large quantities of radionuclides, including radioiodine.Population samples of approximately 100 persons residing in both highly contaminated villages and control villages since the accident were compared. Individuals were selected on the basis of birth date as being 5, 10, 40, or 60 years old at the time of the study. All persons selected underwent a thyroid examination.None.Two main outcome measures were used, both for thyroid nodularity: clinical palpation and high-resolution ultrasonography.There was no significant difference in thyroid nodularity between the study groups. Nodules were palpated in 0.7% of children and 2.9% of adults. Discrete nodules were found by ultrasonography in 0.5% of children and 14.9% of adults. Multinodular goiter was found in 3% of adults. Nodules were more common in females.Four and a half years after the Chernobyl accident, the incidence, prevalence, and characteristics of thyroid nodules were the same in population samples from both highly contaminated and control settlements and similar to results reported for unexposed populations in other countries.

Three hundred and sixteen patients with solitary or dominant thyroid nodules were imaged both with technetium-99m- (99mTc) pertechnetate and iodine-123 (123I). The images were preferred, but differences were small and in 27%-58% of the cases there was no difference in quality between the two radionuclides. Discrepancies between 99mTc and 123I images were found in 5%-8% of cases, twice as often in multinodular goiters as in single nodules. Cytologic/histologic examination was performed on all nodules but no correlation was found between the pathology and the type of discrepancy. Twelve carcinomas were found (4%) but none in nodules showing a discrepancy. There was great variation among the observers about the preference for radionuclides and about the existence or type of discrepancies. The slightly better overall quality of 123I scans is probably not of diagnostic significance and does not justify the routine use of 123I instead of 99mTc. Routine reimaging of 99mTc hot nodules with radioiodine for cancer detection does not appear to be necessary.

It is essential that emergency physicians understand ways to manage patients contaminated by radioactive materials and/or exposed to external radiation sources. Contamination accidents require careful surveys to identify the metabolic pathway of the radionuclides to guide prognosis and treatment. The level of treatment required will depend on careful surveys and meticulous decontamination. There is no specific therapy for the acute radiation syndrome. Prophylactic antibodies are desirable. For severely exposed patients treatment is similar to the supportive care given to patients undergoing organ transplantation. For high-dose extremity injury, no methods have been developed to reverse the fibrosing endarteritis that eventually leads to tissue death so frequently found with this type of injury. Although the Three Mile Island episode of March 1979 created tremendous public concern, there were no radiation injuries. The contamination outside the reactor building and the release of radioiodine were negligible. The accidental fuel element meltdown at Chernobyl, USSR, resulted in many cases of acute radiation syndrome. More than 100,000 people were exposed to high levels of radioactive fallout. The general principles outlined here are applicable to accidents of that degree of severity.

Summary In the quantitative precipitin reaction anti-XI-HSGG is precipitated by sera collected from seven patients at various times before and after treatment with total body radiation. The data are insufficient to determine whether the effects described are due to a direct effect on preformed proteins and/or an effect on the rate of synthesis of pre-existing protein. These studies may provide an approach to a better understanding of radiation-altered immunologic mechanisms in human beings.

We evaluated 1,266 persons who had received external radiotherapy for benign diseases in childhood. The evaluation used detailed questionnaires completed by trained interviewers and neoplastic disease registry data. The control population included 958 age-, sex-, race-, and disease-matched persons who had not received radiotherapy and 9,865 family members of the two study groups. An excess number of clinically important thyroid neoplasms, both benign and malignant, was noted in the irradiated group.

Newly synthesized Tc-99m dichlorobis(1,2-dimethylphosphino)ethane (DMPE) was investigated as a myocardial imaging agent with respect to its kinetics (dependent on both time and regional coronary blood flow), its percent organ uptake, and its imaging characteristics in the anesthetized dog. Most of these data are compared with those of Tl-201. Blood clearance of the two agents is essentially the same. Compared with Tl-201, Tc-99m DMPE shows faster overall kinetics, higher heart-to-lung ratio, equally good correlation with a wide range of regional blood flows, and higher liver uptake. At the time of peak myocardial uptake, the mean heart uptake of Tl-201 is 4.3%, compared with 2.9% for Tc-99m DMPE, yet only 0.9% uptake of Tc-99m DMPE is found in the lung as compared with 3.3% for Tl-201. These differences result in a heart-to-lung ratio of 2:1 for Tc-99m DMPE and 1:1 for Tl-201, based on the data obtained from the time-activity curve. The quantitative findings are supported by the superior quality of Tc-99m DMPE images of both normal and infarcted dog heart. The high hepatic uptake of Tc-99m DMPE is not a serious problem if images are obtained within 5-60 min after dose. These basic kinetic studies suggest that Tc-99m DMPE is a promising myocardial imaging agent.

The cost-effectiveness of pulmonary imaging (lung scan) on the management of 2,023 patients was studied. Prior and postscan probabilities of pulmonary embolism (PE) were obtained from referring physicians. After the scan, anticoagulant therapy (ACT) was appropriately changed in 20% of the patients and confirmed in 67%. The incremental cost of scanning was $124 per patient when the prior probability was 0.01-9.99%, dropping to $38 when the probability was 10-25%. Hospitalization and ACT cost was reduced when the prior probability was 25.01-99.99%. The greatest benefit in lives saved was when the prior probability was 25-74.99%; 1.5% of this probability group would survive as a result of the change in management attributable to the scan, at a cost of $117 per life saved. The benefit:risk ratio, as measured by lives saved compared to estimates of lives lost due to radiation exposure, was of the order of 6,000:1.

Etidronate and pyrophosphate, labeled with Tc-95m and Tc-99m, were studied in experimentally infarcted mongrel dogs. A distribution study was conducted 2 hr after simultaneous administration of both agents in two groups of dogs. In one group, the injection was made 15 min after release of a 2-hr coronary arterial ligation. Another group was injected 48 hr after release of the ligation. The uptakes for each radiopharmaceutical and the ratio of uptakes for each sample were computed. The data show pyrophosphate to be a superior agent for the imaging of acute myocardial infarcts because of the higher uptake by infarcted myocardium and the greater contrast between infarcted myocardium and neighboring organs.

The 14C-tripalmitin breath test has been used routinely in our institution for the diagnosis of fat malabsorption as well as for the differential diagnosis of malabsorption due to pancreatic insufficiency. The test was performed in 124 patients over a period of about three years. The sensitivity and specificity of the test for fat malabsorption were better than 85.7 and 87.0%, respectively, with the efficiency better than 86.4%. When used in conjunction with Viokase administration, the test is useful as a means of separating pancreatic malabsorption patients from patients with other forms of malabsorption.

The diagnosis of intrahepatic aneurysm was suspected following radioisotope scintigraphic studies. A patient developed abdominal pain following blunt abdominal trauma. The scintigrams of the liver revealed a large intrahepatic defect and separation between lung and liver. Angiogram revealed a large false aneurysm of the right hepatic artery.

Detection of breast disease at an early stage was evaluated with 131CsCl. The tissue distribution study showed that malignant tumors could be distinguished from both benign and normal tissue by the degree of 131Cs concentration. However, the external counting method was not sensitive enough to warrant general application to patients with a suspected malignant tumor of the breast. False-positive breast study findings using radionuclides, such as 131CsCl, require close follow-up study in view of possible malignant changes in benign disease of the breast.

An information-theoretic pattern recognition method was used to construct descriptive models of data related to 1,674 radioisotope lung scan referrals for the purpose of assessing lung scan influence on diagnosis and management of pulmonary embolism. It was observed that, relative to other clinical information available prior to the scan, the lung scan significantly improved the ability of the models to predict diagnostic and management outcomes, implying that the lung scan has significant influence on these clinical decisions.

129CsCl was investigated as an agent for imaging tumors of the lung, and based on the results of 56 patients studied, it has proved to be highly sensitive in detecting primary malignant tumors of the lung. The differentiation between pulmonary malignant lesions and tuberculosis appears to be feasible. However, false-positive images in patients with benign conditions are inevitable.

Thallium-201, 129Cs, 43K, and 81Rb were evaluated as "static" myocardial-imaging agents. Optimal settings of the scintillation camera were determined for each agent. Accumulation for good-quality images can be started as early as 5 min after the dose with 43K, 10 min with 201T1, and 30 min with 129Cs. Imaging times were comparable for 43K, 129Cs, and 201T1 (using the 80-keV x-rays). High-energy photons from the 81Rb preparation, largely from 82mRb contaminant, made it impossible to obtain an interpretable image without the addition of more shielding. Absorbed radiation dose from 81Rb is lower than that from 43K, 129Cs, and 201T1. The highest background activity was observed with 81Rb, followed by 43K, 129Cs, and 201T1 in that order. Overall, 201T1 was best suited for imaging acute myocardial infarction with currently available equipment, and 129Cs was next best. However, because of instrument setting and commercially obtained preparations, 81Rb could not be properly compared with the other radionuclides in our study.

This paper describes a Society of Nuclear Medicine sponsored study of 2,023 patients which compares two methods, logistic regression (LR) and entropy minimax pattern detection (EMPD), to evaluate efficacy. Lung scans, used in determining or excluding a diagnosis of pulmonary embolism (PE), were utilized to create the data set. The LR analysis, presented here, shows that lung scan findings have significant influence on the referring physician's diagnostic thinking. Models were developed for the probability of a signout diagnosis of PE, and equal patient groups tested the validity of these regression equations. Individual models developed on each patient group yielded similar results. This analysis shows that the lung scan results affect the therapeutic management of the patients in a beneficial direction. A comparison of the sensitivity, specificity, and predictive values of EMPD and LR was done. EMPD predicts a signout diagnosis on only 41% of cases before lung scan and 71% after lung scan; LR provides a prediction of the signout diagnosis on 100% of cases. An advantage of EMPD is that it does not require prior probability estimates. However, LR uses this estimate, thus incorporating intuitive knowledge not evaluated by EMPD.

It is customary to use the LD50 response as a criterion for the evaluation of chemical radioprotection. The increased urinary excretion of deoxycytidine (CdR) in irradiated rats has been shown to be a linear dose--response relationship up to 200 R, thus making it possible to consider such a response as a criterion for chemical radioprotection evaluation at sub-lethal irradiation levels. Rats were subjected to 200 R X-irradiation with various chemical protectors and without chemical protectors, urine was collected 24 hours after irradiation, and the CdR levels in the urine analysed. A dose-reduction factor (DRF) was determined for 24-hour urinary excretions of CdR for chemically protected and non-protected rats. The DRF values are within 6 per cent of those reported by other investigators using LD50 as the response criterion for serotonin, cysteine, MEA and PAPP but differ for WR-2721 and WR-2823. Agreement using WR-2721 and WR-2823 compounds is only obtained when the toxicity effect of the compound is taken into consideration.

After intravenous administration of Tc-99m DMPE the flow-dependent kinetics were studied in dogs during induced ischemia and during induced maximal reactive hyperemia. A control group was also studied. Mean time-activity curves obtained from the myocardial wall were compared within the same intervention group and also with other groups. During reactive hyperemia, there was a rapid and absolute increase in uptake followed by a rapid washout, whereas during ischemia there was a slow and decreased uptake followed by a slow washout. The magnitude of Tc-99m DMPE uptake during reactive hyperemia was slightly less than that of Tl-201, but the decreased uptake with ischemia was about equal for the two agents. Following maximal uptake in the myocardium the effective half-life of Tc-99m DMPE was one-third to one-fourth that of Tl-201. The similar kinetics of Tc-99m DMPE compared to Tl-201 suggests its usefulness in the evaluation of ischemic heart disease.

A Gamut is defined as a complete list of anything. As utilized here, it indicates a complete list of the possible causes of a particular scintigram finding. The procedure for developing a Gamut is discussed, ant its use as a tool for instructing residents in nuclear medicine is described. Sample Gamuts are presented and the Gamut approach to scintigram differential diagnosis is described.

Individual observers interpreted images in order to assess their accuracy and sources of error. Seventy-six liver images were presented to nine readers for interpretation. Readers of differing experience participated in the study: four radiology residents, three fellows in nuclear medicine, and two full-time nuclear medicine physicians. A higher incidence of false-positive reading was more common in inexperienced observers (11-50%) and the most correct readings were obtained by staff physicians (88% overall percentage accuracy). Heterogeneity in radionuclide uptake was the most frequently ill-defined nature was the most common false-positive finding in normal cases. Early stages of cirrhosis, mild hepatitis, and rare diseases such as hepatic sarcoidosis were difficult to detect. Skill of interpretation improved with experience, especially in judging heterogeneity of an ill-defined nature, and the rate of accurate readings was proportional to the level of training of the observer.

CONTRIBUTIONS to medical sciences depend on the willingness of the research physician to use the computer as a matter-of-fact tool, just as he uses the microscope and other instruments. Where such conditions exist, contributions of some importance may be expected to emerge. At the University of Cincinnati Medical Center a computer has been used in such fashion for 5 years and one can already point to the direction in which future developments will take place. Criteria selected for our program are statistical as well as medical and serve to eliminate variables of no further interest in a consecutive search among possible multiple associations. Internal safety checks are built into the program which gauge the accuracy with which relevant associations are selected by the program. The output of the program consists of a partially written report of variables found to be associated, relevant tables, and an index of possible associations that were eliminated as unimportant together with reasons for their rejection. The basic outline of the program and its detailed application to a study of thyroid disease will be described.

A synopsis of scheduled extravehicular activities (EVA) for a nominal Skylab mission is presented with an overview of EV workstation equipment developed for the program. Also included are the unprogrammed extravehicular activities and supporting equipment that was quickly developed and retrofitted in a series of successful operations to salvage the crippled Skylab Cluster during the Skylab 1 Mission. Because EVA appears to be a requirement for the Space Shuttle Program, candidate EV workstations are discussed in terms of effective and economical Shuttle payload servicing and maintenance. Several such concepts, which could provide a versatile, portable EV support system, are presented.

Space tools and supporting equipment developed for past and current missions are summarized, along with projected tool and powered maneuvering aid requirements for future earth orbital missions. These tools, designed for functions such as general maintenance, replacement and repair, are reviewed and classified according to their intended application. A synopsis of the Skylab on-orbit maintenance requirements is presented, and the tools necessary for accomplishing the maintenance functions are listed. The proposed missions for future Earth Orbital Systems are summarized, and the potential functions (e.g., Remove/Replace, Cargo Transfer, etc.) are outlined. The current tool and support technology status is compared with future requirements for crew equipment to determine if these future requirements can be adequately satisfied. Of particular interest is a discussion of the augmentation of the astronaut with teleoperators (remote manipulator systems).

A number of reports have suggested the wider use of Iodine-123 as the ideal radioisotope of iodine because of its theoretical advantages. A short Half-life of 13,3 h, a primary gamma photon of 159 keV of high abundance and absence of beta particle emission result in a dose reduction variously estimated at 30–100 fold over commonly used Iodine-131. In addition, the low energy 159 keV gamma and a lesser abundant 28 keV X-ray offer promise of improved imaging resolution utilizing low energy high resolution collimators.