title: Lacrimal Glands May Represent Organs at Risk for Radionuclide Therapy of Prostate Cancer with [(177)Lu]DKFZ-PSMA-617.
abstract: Calculating the absorbed dose is important for the determination of risk and therapeutic benefit of internal radiation therapy. The aim of this study was to perform image-based absorbed dose calculation for critical organs during the first cycle of [(177)Lu]DKFZ-PSMA-617 therapy in a small cohort of patients with metastatic prostate cancer.
  
  
  
  Nine patients with a history of prostate cancer documented by histopathology and radiologic evidence of metastatic diseases underwent radioligand therapy with [(177)Lu]DKFZ-PSMA-617. Conjugated planar whole-body scintigraphies acquired at 0.5, 24, 48, 72, and 168 h post-injection were analyzed by regions of interest, and time-activity curves were generated for various organs. Cumulated activities and residence times were calculated by bi-exponential fit of the time-activity curves. Mean absorbed doses were finally estimated using OLINDA/EXM1.1™. Additionally, the uncertainty when omitting the last measurement (168 h p.i.) was studied.
  
  
  
  The following mean absorbed doses were calculated: 2.82 mGy/MBq for the lacrimal glands, 0.72 mGy/MBq for the salivary glands, 0.53 mGy/MBq for the kidneys, and 0.42 mGy/MBq for the nasal mucous membrane. Omitting the last measurement resulted in a mean deviation of 10 to 25 % for absorbed dose values as compared to the ones received by analyzing all measurements.
  
  
  
  Absorbed organ doses of [(177)Lu]DKFZ-PSMA-617 therapy are not likely to be critical for kidneys, salivary glands, and the nasal mucous membrane. The lacrimal glands may represent the dose-limiting organs. Whole-body scintigraphy appears sufficient for dose estimation, but late measurements are mandatory, if accurate dose calculation is required.
authors.affiliation: Department of Nuclear Medicine, University Hospital of Cologne, Kerpener Str. 62, Cologne, 50937, Germany. melanie.hohberg@uk-koeln.de.
authors.forename: Melanie
authors.initials: M
authors.lastname: Hohberg
authors.affiliation: Department of Nuclear Medicine, University Hospital of Cologne, Kerpener Str. 62, Cologne, 50937, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Eschner
authors.affiliation: Department of Nuclear Medicine, University Hospital of Cologne, Kerpener Str. 62, Cologne, 50937, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Schmidt
authors.affiliation: Department of Nuclear Medicine, University Hospital of Cologne, Kerpener Str. 62, Cologne, 50937, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Dietlein
authors.affiliation: Department of Nuclear Medicine, University Hospital of Cologne, Kerpener Str. 62, Cologne, 50937, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Kobe
authors.affiliation: Department of Nuclear Medicine, University Hospital of Cologne, Kerpener Str. 62, Cologne, 50937, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Fischer
authors.affiliation: Department of Nuclear Medicine, University Hospital of Cologne, Kerpener Str. 62, Cologne, 50937, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Drzezga
authors.affiliation: Department of Nuclear Medicine, University Hospital of Cologne, Kerpener Str. 62, Cologne, 50937, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Wild
mesh_terms: D000368:Aged; D003710:Demography; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D007765:Lacrimal Apparatus / Q000000981:diagnostic imaging*; D008187:Lutetium; D008297:Male; D008875:Middle Aged; D009942:Organometallic Compounds / Q000737:chemistry*; D058958:Organs at Risk / Q000528:radiation effects*; D017430:Prostate-Specific Antigen; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D013997:Time Factors; D014018:Tissue Distribution / Q000528:radiation effects; D051598:Whole Body Imaging
chemical_list: C000622701:177Lu-DKFZ-PSMA-617; D009942:Organometallic Compounds; D008187:Lutetium; D017430:Prostate-Specific Antigen
keywords: Dosimetry; Lacrimal glands; PSMA; Prostate cancer; Radioligand radiation therapy