COMPARISON BETWEEN CLINICAL DOSIMETRIC PLATFORMS IN NET PATIENTS TREATED WITH PRRT

Background: This work aims to quantitatively compare the main clinical platforms developed for Metabolic RadioTherapy (MRT). Data analysis concerned dosimetric monitoring of patients who benefited from Lu-177-DOTATOC PRRT treatments, specifically kidneys and significant lesions (ROIs). We compared calculated absorbed doses between a pure voxel dosimetry approach [1], HMS® OLINDA/EXM 2.0, PLANET® Onco Dose and MIM® MRT [2]. MIM® MRT allows voxel dosimetry both patient-specific and phantom based. Material and Methods: We analyzed data of 10 NET patients treated with personalized activity, performing sequential SPECT-CT dosimetry at 3 time points. To obtain dose rates with our voxel dosimetry approach, the convolution [1] between the Dose Voxel Kernel (DVK) and patient SPECT data was performed for each time point. Then, the dose-rate curves have been fitted with a bi-exponential function and by integrating this function, the absorbed doses were derived. Finally, we compared these results with those returned by the clinical platforms, processing the same ROIs for each patient. Preliminary Results: The comparison highlights a discrepancy between the voxel dosimetry approach and PLANET® Onco Dose and MIM® MRT, when the phantom-based voxel dosimetry approach is used. Moreover, notice that, only if MIM® MRT employs the patient-specific voxel dosimetry approach, results agree with the other two procedures, since in both the workflow passes through the convolution of SPECT/CT patient images with Lu-177 dose point kernel [1]. A discrepancy in dosimetry results appears when different workflows are used. An overestimation of absorbed doses within kidneys seems to appear when a phantom-based voxel dosimetry approach is used. For significant lesions, however, it seems not to be a systematic trend. Results need to be validated by increasing the patient cohort dimension.