Quantitative Radiocardiography

L. DONATO, D. F. ROCHESTER, M. L. LEWIS, J. DURAND, J. O. PARKER, R. M. HARVEY
1962 Circulation  
ON THE BASIS of theoretical considerations previously presented' a method has been developed for the measurement of cardiac output, right ventricular and pulmonary blood volumes. The present paper deals with a description of the instrumentation and of the procedure employed to secure radiocardiograms and with the technic of analysis of the curves. Method Instrumentation Time activity curves are recorded by means of a scintillation counter, with a NaI crystal 11/2 inches in diameter, located in
more » ... ameter, located in a lead collimator with a straight bore of the same diameter. The crystal surface is recessed 10 cm. from the external opening of the collimating channel. The efficiency distribution for this collimated counter is represented in figure 1 of the previous paper.1 This distribution was determined by means of a point source suspended in a cylinder of water to simulate the chest. With this collimator, activity anywhere in the four heart cavities may contribute to the counting rate. Since the fraction of the lungs included in the field is small and the counting efficiency of this fraction is considerably less than that of any heart cavity, the contribution of the lungs to the precordial counting rate is minimal. Pulses from the photomultiplier tube are amplified and fed into a counting ratemeter and into a scaling circuit. The output of the ratemeter is fed into a multichannel electronic recorder, with monitoring oscilloscope, which is adjusted so that there is approximately 1 mm. paper deflection for 800 counts per minute when the 100,000 epm scale of the ratemeter is utilized. The response both of the ratemeter and the recorder is linear. A paper speed of 2.5 cm. per second is generally used for record-
doi:10.1161/01.cir.26.2.183 fatcat:eesuynh2jjb5pbjwlgylmy6tvm