A portable cadmium telluride multidetector probe for cardiac function monitoring

A 200 g portable probe containing a square array of 16 CdTe detectors+preamplifiers and a collimator has been used for ventricular function studies. A bias voltage of 30 V yielded long term stability. An interface included the 16 amplifiers, discriminators and counters, and 2 leads ECG channels. The counting rate characteristics of each detector was studied to calculate a software correction matrix of the raw data. 70 non-ambulatory patients were injected with 370 MBq of ⁹⁹Tc. At first a gamma camera yielded a reference ventricular curve and the adjustment of the probe position on the chest. The patients in supine position were studied at rest for 5 min and underwent three increasing 25 W steps of exercise and recovered for 6 min. At rest the ventricular curves were clearly depicted, and different response patterns were observed during exercise. A full Holter ambulatory system is now on project