An Improved Data Recorder for Scintillation Cameras

A tape-recording system using a variation of pulse-width modulation records up to 28,000 Hz from an Anger camera without spatial or temporal distortion and with less than 1% data loss. Recording and playback may be made at any of five tape speeds: 3¾, 7½, 15, 30, 60 ips, each accommodating a different maximal counting rate. Since only two of four recording tracks are used, the others are available for other input. The replayed data appear in a format identical to the gamma camera signal; hence, any data manipulation performable on the original signal can be carried out on the replay. The system has advantages over other gamma camera recording systems: matrix artifact is eliminated; replay time may be accelerated or decelerated depending upon study objectives; when data are digitized for computer manipulation, data losses caused by deadtime are limited to those intrinsic to the gamma camera itself.