Accuracy of the Quantification of Organ Activity from Planar Gamma Camera Images

Abstract

The accuracy in determination of organ activity of (99m)Tc was investigated, with activity estimated from gamma camera images of phantoms, using the conjugate view method. The accuracy depends on several parameters such as the choice of background correction method, the accuracy in determination of the effective attenuation coefficient and the thickness of the body and organs and on the determination of the gamma camera sensitivity. The background correction method has a major influence on the quantification of the activity. Methods which take the volume of the source organ into consideration are recommended. The discrepancy in the determined organ activity varied between an underestimation of 26% and an overestimation of 16% in the MIRD phantom, depending on which organ was studied and on the correction method used. To correct for absorption and scattering, an effective attenuation coefficient was used. A theoretical analysis showed that a change in the effective attenuation coefficient of 0.01 cm(-1) resulted in a 15% change in the calculated activity. Also the thickness of the body and the organ of interest influences the calculated activity. A 2 cm deviation in the body thickness causes a deviation of approximately 10% in the calculated activity. The quantification is improved if the attenuation coefficient is determined by transmission measurements.

Dosimetric results in treatments of neuroblastoma and neuroendocrine tumors with 131I‐metaiodobenzylguanidine with implications for the activity to administer

“…The main contribution to Drm was the crossabsorbed dose from the remainder of the body, and the relative standard deviation for Drm 190 was thus also estimated to be 20%. These uncertainties are in line with values suggested by others 33,34 .…”

Pre-therapeutic dosimetry of normal organs and tissues of 177Lu-PSMA-617 prostate-specific membrane antigen (PSMA) inhibitor in patients with castration-resistant prostate cancer

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Pediatric radiation dosimetry for positron‐emitting radionuclides using anthropomorphic phantoms

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