The purpose of this study was to determine the attenuation characteristics of tomographic imaging tables and to evaluate these effects on prone and supine imaging of the heart, using a cardiac phantom. Methods: Table attenuation as a function of imaging angle was measured in seven different types of tomographic imaging tables, by imaging 99mTc and 201Tl line sources placed at various distances above the center-line of the table. Three imaging tables exhibiting low, medium and high attenuation were further studied using a cardiac phantom filled with 201Tl to see the effects of attenuation on myocardial image quality. Studies were performed under three conditions: no table, table above phantom (prone imaging) and table beneath phantom (supine imaging). Circumferential count profiles were generated from short-axis slices of the myocardium. Results: Most SPECT tables attenuated only 5%-10% (99mTc) and 8%-12% (201Tl) at an angle of 180° (face of detector parallel to table). At angles of 90° and 270°, however, table attenuation was highly dependent on the tables' design and material content. From the cardiac phantom studies, short-axis circumferential count profiles showed no significant difference for low-attenuation tables and a slight difference (<5%) in the septal region for medium-attenuation tables. In prone imaging, high-attenuation tables caused a reduction in counts in the antero- lateral wall (>10%) and in the septum (>5%). Conclusion: Table attenuation characteristics should be considered when comparing studies from different systems and in establishing a normal database for 201Tl polar maps. High- attenuation tables should be used with caution in cardiac studies.
|Original language||English (US)|
|Number of pages||5|
|Journal||Journal of Nuclear Medicine|
|State||Published - Jan 1 1995|
- single-photon emission computed tomography
- tomographic table