Kwantifisering van radionukliedverspreiding deur planare beelding met 'n sintillasiekamera

[摘要] English: In this study attenuation and scatter correction techniques in planar imaging wereinvestigated as well as the practical implementation of these techniques in clinicalstudies.The attenuation correction technique that was investigated was the geometrical meanmethod where an iterative method was used to determine the attenuation coefficient.This adaptation made the attenuation correction method independent of depth. In thisstudy the depth dependence of the geometrical mean method was solved which is animportant contribution.The three-energy window scatter correction technique was investigated with MonteCarlo methods for planar imaging. These simulations showed that the scattercorrection method under corrects by approximately 10%. The scatter correctiontechnique cannot be performed on it's own but must be used in conjunction with theattenuation correction method.The overall effect of the quantitation (attenuation and scatter correction) wasdetermined in two ways. First a known amount of activity was imaged. Then thecorrection was applied to the images. Subsequently the corrected activity obtainedfrom the latter images was compared to the known value. The calculated activity was98,6 % of the known activity value. Secondly clinical studies were performed wherethe bladder activity was quantitated in vivo and correlated to the in vitro measuredvalue. In this case the correlation coefficient was 0,996.The quantitation technique was applied to the clinical determination of the glomerularfiltration rate. The quantitation technique was compared to the routine method thatrequires handling of urine. The correlation coefficient was 0.96 and the linearregression line had a slope ofO.91 and a y-axis intercept of4.8l. The quantitation ofthe bladder activity leads to a simplification of the clinical study procedure since thephysical handling of urine can be eliminated. The accuracy of this method dependson the conversion factor that compensates for the difference between the sensitivity ofthe camera and the well counter. This factor must be checked on a regular basis toensure the accuracy of this method.The bladder as source organ was used in this study. The bladder is a relative isolatedorgan and therefor the influence of radioactive uptake in other organs is relativelysmall. If these quantitations are applied to organs that are not isolated, i.e. the heartwhere the liver can influence it, this problem has to be address.In this project a quantitative planar imaging technique was investigated that correctsfor attenuation and scatter and thereby facilitates depth independent corrections.

[发布机构] University of the Free State