title: Uncertainty propagation for SPECT/CT-based renal dosimetry in (177)Lu peptide receptor radionuclide therapy.
abstract: A computer model of a patient-specific clinical (177)Lu-DOTATATE therapy dosimetry system is constructed and used for investigating the variability of renal absorbed dose and biologically effective dose (BED) estimates. As patient models, three anthropomorphic computer phantoms coupled to a pharmacokinetic model of (177)Lu-DOTATATE are used. Aspects included in the dosimetry-process model are the gamma-camera calibration via measurement of the system sensitivity, selection of imaging time points, generation of mass-density maps from CT, SPECT imaging, volume-of-interest delineation, calculation of absorbed-dose rate via a combination of local energy deposition for electrons and Monte Carlo simulations of photons, curve fitting and integration to absorbed dose and BED. By introducing variabilities in these steps the combined uncertainty in the output quantity is determined. The importance of different sources of uncertainty is assessed by observing the decrease in standard deviation when removing a particular source. The obtained absorbed dose and BED standard deviations are approximately 6% and slightly higher if considering the root mean square error. The most important sources of variability are the compensation for partial volume effects via a recovery coefficient and the gamma-camera calibration via the system sensitivity.
authors.affiliation: Department of Medical Radiation Physics, Clinical Sciences Lund, Lund University, S-221 85 Lund, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Gustafsson
authors.forename: Gustav
authors.initials: G
authors.lastname: Brolin
authors.forename: Maurice
authors.initials: M
authors.lastname: Cox
authors.forename: Michael
authors.initials: M
authors.lastname: Ljungberg
authors.forename: Lena
authors.initials: L
authors.lastname: Johansson
authors.forename: Katarina Sjögreen
authors.initials: KS
authors.lastname: Gleisner
mesh_terms: D015902:Gamma Cameras; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007668:Kidney / Q000000981:diagnostic imaging*; D009010:Monte Carlo Method; D015282:Octreotide / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000627:therapeutic use; D009942:Organometallic Compounds / Q000493:pharmacokinetics / Q000627:therapeutic use*; D019047:Phantoms, Imaging; D011874:Radiometry / Q000379:methods; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D018000:Receptors, Peptide / Q000378:metabolism*; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D035501:Uncertainty
chemical_list: D009942:Organometallic Compounds; D019275:Radiopharmaceuticals; D018000:Receptors, Peptide; C447941:lutetium Lu 177 dotatate; D015282:Octreotide