IN-VIVO ESTIMATION OF RADIATION-DOSE IN RENAL PELVIS AND PARENCHYMA DURING RENOGRAPHY

A method is presented for the determination of the spatio-temporal dis tribution of the radionuclide in the kidney and estimation of the dose in the renal pelvis wall and parenchyma, during renograms, on the bas is of real data. A protocol was formulated by means of which the proce ssing of the frames acquired in the various stages of the renogram ena bles the determination of the mass of the renal pelvis and the parench yma as well as the time distribution of radioactivity in these compart ments. The proposed methodology was applied to 30 normal subjects and 35 patients with obstructive nephropathy, acute and chronic obstructiv e uropathy and hydronephrosis. Our results, when compared with the MIR D dose estimations for the entire kidney showed slight deviations in n ormals, whereas very significant deviations were observed in the cases with pathology. This is due to the fact that the mass of the 'source' and 'target' organs as well as the biodistribution of the radiopharma ceuticals are essential in dose determination and were completely diff erent in our calculations from those used in the MIRD estimations. Com paring the absorbed dose in renal parenchyma and pelvis wall with that estimated in vivo for the kidney considered as a system of one compar tment, we found large differences only in abnormal cases. Differences were also noted between the absorbed dose in the aforementioned renal compartments depending on the considered abnormal renal states.