Comparison Of Methods Of µ-Map Generation: Mr-Based Method In Pet/Mr Imaging Versus Pseudo-Ct Method In Radiotherapy Dose Planning

ABSTRACT The main objective of this study was to compare the similarities and differences in MRbased and pseudo CT µ-map generation in PET/MR and radiotherapy respectively. The study sought to look at ways attenuation correction could be done on PET hybrid imaging systems and compare them in various ways so as to improve treatment and patient care. The methodology involved patient selection, image processing and generation of both µmaps for PET-attenuation correction and pseudo CT for radiotherapy dose planning from computational software packages. MR-based µ-maps were successfully been generated and could be used to correct for attenuation in PET. Pseudo CTs were also successfully generated and could be used in radiotherapy for dose planning. For head images, it was observed that MR- based µ-maps over-estimated the bone as compared to CT µ-map for two patients, with deviations of 4.0% and 4.2%. Also, for head images, it was observed that the µ-values of bone for both MR-based and CT µ-maps were dynamic and had continuous values. For the pelvis, it was found that the pseudo-CT underestimated the bone volume as compared to CT µ-map in five patients, with deviations of 18.7%, 21.3%, 9.6%, 14% and 10%. It was observed that the µ-values of bone for pseudo-CT were not dynamic and also did not have continuous values as compared to CT µ-map. It was also observed from the pelvis studies that the µ-values for muscle were more dynamic and had a greater range in CT µ-map than the pseudo CT and MRI µ-map.