Computer analysis of compton scattering images: acquisition, restoration and application in patients with pulmonary edema

In Pisa, at the Istituto di Elaborazione dell ' Informazione, in cooperation with the Istituto di Fisiologia Clinica, a tomographic method that allows the visualization of frontal and sagittal planes of a chest was developed, in order to detect regional lung density changes due to pathologica1 processes [1]. Sectional visualization of the chest is obtained by employing a collimated linear source of gamma photons and a gamma camera as imaging device - to detect the Compton scattering at 90° to the primary beam. Imaging 90° scattered rays provide a view of the anatomical crossection corresponding to the path of the primary rays in chest tissues. Chest tomographic views with 500 K counts are ,obtained in 1 or 2 min with the spatial resolution of the gamma camera and with tissue density discrimination of 12% on average, as shown by phantom studies. The maximum estimated radiation dose to the patient is about 0.09 rads for each view. This radiation load is comparable to that of standard chest x-ray and considerably less than that of conventional or computerized x-ray tomography.