Compton scatter imaging of transverse sections: an overall appraisal and evaluation for radiotherapy planning

A Compton scatter scanner has been developed to image electron density distributions of transverse body sections. The imaging performance of this device has been measured and compared with calculated limits and with the present capabilities of X-ray computed tomographic (CT) scanners. The use of Compton scatter images in radiotherapy dose calculations has been investigated and a calibration curve has also been measured from patient images to convert CT number data to electron densities for tissues in vivo. Images have been produced with a spatial resolution of 0.5 cm and an electron density accuracy of 4.3% for a radiation dose of 0.11 Gy (11 rad) to the patient. However, little potential remains for further development of the Compton scatter technique for whole-body imaging.