Measurement of photon attenuation from different cardiac chambers

TL;DRAbstract

Accounting for the attenuation (AT) of photons within cardiac chambers is crucial to accurate non-geometric volume determinations from gated blood pool scintigraphy. Previous techniques to determine AT for each patient have assumed an attenuation factor of 0.15/cm for Tc-99m, the value of water. To verify this, the authors determined the AT at various tissue distances (TD) in vivo. As a point source they used the balloon of a 5 French Swan-Ganz catheter which could reproducibly be filled with a constant amount of Tc-99m and could be placed within the left or right cardiac chambers. The exact location of the balloon, once inflated, and the TD from the balloon to the collimator of a small field-of-view Anger camera was determined using biplane orthogonal fluoroscopy. AT was determined by counting the inflated Tc-99m filled balloon in air and dividing that value by the counts of the same balloon within the heart. The authors positioned the balloon in the apex of the right and left ventric

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