A Comparison of Thyroid Scintigrams between by Scanner and by Camera

The most characteristic value of scintillation camera is its high sensitivity compared that of scanner. Consequently the time needed to get scintigrams is shortened specially in high dose distribution of radioisotopes, just as to have heart pool dynamic scintigrams with one second intervals. In this paper another view point of scintillation camera, the problem of resolution, is discussed on the thyroid scintigrams. Phantom studies are shown in scintigrams both by scanners and cameras using line phantom (Fig. 2) . The evaluations of the scintigrams by scanner are depend on many factors, they are energies selected, crystal size, nature and dose of radioisotopes, representation system and geometry and efficiency of collimators. To have the complete evaluation, the scintigrams must be discussed as a matrix of all of these factors, but in this paper mainly because of its complexity, each factors are discussed separately (Fig. 3-8) . On camera the distance between collimators, multiparallel hole and pinhole, are examined (Fig. 9-10) . The clinical data are also shown as scintigrams by both apparatuses (Fig. 11-15) . As a result, the thyroid scintigrams by camera with pinhole collimator is usually superior that of scanner in the point of resolution and clinical evaluation. The procedures and time needed are also summarized and in busy clinics the camera is suggested as a more preferable apparatus in thyroid scintigram study.