James K. Langan

Urokinase in Pulmonary Embolism

THE use of thrombolytic enzymes or their activators has been proposed as a treatment of thromboembolic diseases such as pulmonary embolism. Using streptokinase as the plasminogen activator, Johnson...

Radioactive xenon in the differential diagnosis of pulmonary embolism.

LUNG SCANNING after the intravenous injection of radioactive particles is a useful procedure in the diagnosis of pulmonary embolism (1). At times the diagnosis cannot be made with certainty on the basis of the scan alone, since other diseases of the lung often result in pulmonary avascularity (2). The occurrence of the characteristic pattern of concave defects at the lateral borders of the lungs without evidence of a corresponding parenchymal lesion on the chest radiograph makes the diagnosis of pulmonary embolism more certain (3), but this is not a constant finding. The differential diagnosis between pulmonary embolism and chronic obstructive pulmonary disease is particularly difficult. For example, in a study of 62 patients with pulmonary emphysema, 95 per cent of the patients had regions of decreased pulmonary arterial blood flow as revealed by lung scanning (4). Such decreases in pulmonary arterial blood flow have been encountered in other pulmonary diseases, but the frequent finding of a normal chest...

Nuclear medicine practices in the 1950s through the mid-1970s and occupational radiation doses to technologists from diagnostic radioisotope procedures.

AbstractData on occupational radiation exposure from nuclear medicine procedures for the time period of the 1950s through the 1970s is important for retrospective health risk studies of medical personnel who conducted those activities. However, limited information is available on occupational exposure received by physicians and technologists who performed nuclear medicine procedures during those years. To better understand and characterize historical radiation exposures to technologists, the authors collected information on nuclear medicine practices in the 1950s, 1960s, and 1970s. To collect historical data needed to reconstruct doses to technologists, a focus group interview was held with experts who began using radioisotopes in medicine in the 1950s and the 1960s. Typical protocols and descriptions of clinical practices of diagnostic radioisotope procedures were defined by the focus group and were used to estimate occupational doses received by personnel, per nuclear medicine procedure, conducted in the 1950s to 1960s using radiopharmaceuticals available at that time. The radionuclide activities in the organs of the reference patient were calculated using the biokinetic models described in ICRP Publication 53. Air kerma rates as a function of distance from a reference patient were calculated by Monte Carlo radiation transport calculations using a hybrid computational phantom. Estimates of occupational doses to nuclear medicine technologists per procedure were found to vary from less than 0.01 &mgr;Sv (thyroid scan with 1.85 MBq of administered 131I-iodide) to 0.4 &mgr;Sv (brain scan with 26 MBq of 203Hg-chlormerodin). Occupational doses for the same diagnostic procedures starting in the mid-1960s but using 99mTc were also estimated. The doses estimated in this study show that the introduction of 99mTc resulted in an increase in occupational doses per procedure.

Tomographic imaging with the scintillation camera in the detection and characterization of brain lesions.

Abstract In a preliminary evaluation of 50 patients suspected of having neurological disease, tomography contributed significantly to the diagnosis, location, and delineation of mass lesions of the brain. Further evaluation of tomography is in progress.

A Display and Storage System for Radionuclide Imaqes1

The system of data processing and storage of scanning and camera images described in this report is one which we have used in our department for the past three years. This system has a number of unique advantages: (a) all original data are retained in the department; (b) scintillation camera and rectilinear scan images are viewed life-size in the same format: (c) file space is greatly reduced; (d) retrieval and analysis of data are facilitated; and (e) duplicate copies can be made quickly, easily, and cheaply. Scintillation camera oscilloscope images are recorded directly on 35 mm film, using a single-lens reflex camera (Fig. 1). Only the amount of film needed for one patient is loaded into the camera, so that the results are available before the patient leaves the department. We have selected 35 mm film that can be processed within ninety seconds. Kodak High Contrast Copy Film is used for brain scans. For dynamic studies, when higher film speed or a wider gray scale is needed, Kodak RAR 2498 is used. Rec...