Dosimetric Variability Across a Library of Computational Tumor Phantoms

The MIRD Schema for Radiopharmaceutical Dosimetry: A Review

“…Three-dimensional suborgan dosimetry is doable using voxel S values (35), as is cellular and subcellular dosimetry using cell S values and the MIRDcell software (38,39). With ongoing advances in radiopharmaceutical therapy, adaptation of the MIRD schema to patient-specific dosimetry, including tumor dosimetry (41), is well under way, with scaling of reference anatomicmodel organ S values to individualized S values and firstorder calculation of tumor self-doses (19,25). Further, the MIRD committee is now addressing the radiation biology of radiopharmaceutical therapy (3) (including a-particle therapy (42)) and the methodologies for acquisition of the relevant time-activity data for patient-specific dosimetry (43)(44)(45).…”

“…Importantly, in addition to its traditional hard-copy resources-the peer-reviewed MIRD pamphlets and associated publications-the MIRD committee has created and is expanding the MIRDsoft website for providing a suite of freely downloadable software tools for radiopharmaceutical dosimetry. MIRDsoft currently hosts MIRDcalc (for organ-level and tumor dosimetry, including such novel features as error propagation) (19,25) and MIRDcell (for not only cellular and subcellular dosimetry but also bioeffect modeling) (38,39). Near-term additions to MIRDsoft will include MIRDfit (for curve fitting, with error propagation, of radiopharmaceutical time-activity data), MIRDy90 (for 90 Y-microsphere dosimetry for radioembolic therapy of liver tumors), MIRDrelease (for assessment of the releasability of radiopharmaceutical therapy patients and of the duration of postrelease precautions), and MIRDct (for individualized CT dosimetry).…”

“…For several source-target pairs, in fact, the differences in S values are up to 10-fold. Modern implementations of the MIRD schema (including the MIRDcalc software (19,25)) generally use the S values for the family of ICRP voxel-based phantoms (18).…”

“…Alternatively, various mathematic formulas may be applied to estimate, approximately, patient-specific organ S values from those of reference anatomic models. A first-order approach for such estimation has been implemented in MIRDcalc (19,25). The OLINDA/EXM computer program also includes an adjustment for organ size for organ-level dosimetry (31).…”

Lesion Dosimetry for [177Lu]Lu-PSMA-617 Radiopharmaceutical Therapy Combined with Stereotactic Body Radiotherapy in Patients with Oligometastatic Castration-Sensitive Prostate Cancer

“…Optimal threshold depends on multiple factors such as lesion size and lesion-tobackground ratio (42). RCs also depend on factors other than the volume of the object, such as shape and activity distribution, with the dependence being largest for extreme departures from spheric geometry (43). No account was taken of nonuniform RPT dose distribution.…”