title: Radiation emission from patients treated with holmium-166 radioembolization.
abstract: OBJECTIVE
  To assess the radiation exposure to individuals coming from patients after treatment with holmium-166 ((166)Ho) microspheres.
  
  
  METHODS
  Holmium-166 radioembolization (RE) with escalating whole-liver doses of 20 Gy, 40 Gy, 60 Gy, and 80 Gy was administered to 15 patients. Exposure rates (μSv/h) from patients were measured at 1.0 m distance from a lateral and frontal position at 0, 3, 6, 24, and 48 hours after infusion. The total effective dose equivalent (TEDE) to a maximally exposed contact was calculated in accordance with guidelines of the U.S. Nuclear Regulatory Commission (NRC). Results were extrapolated to a whole-liver dose of 60 Gy used in future treatments.
  
  
  RESULTS
  The median exposure rate at discharge, 48 hours after infusion, measured from a lateral position was 26 μSv/h (range, 7-45 μSv/h). Extrapolated to a whole-liver dose of 60 Gy, none of the exposure rates for the NRC contact scenario, at any time, frontal or lateral, would lead to a TEDE > 5 mSv; all patients may be released directly after treatment. Release after 6 hours is possible without contact restrictions for patients who received up to 7 GBq.
  
  
  CONCLUSIONS
  The TEDE to a contact of patients treated with (166)Ho RE would not exceed the NRC limit of 5 mSv. Contact restrictions 6 hours after treatment are unnecessary for infused activities < 7 GBq.
authors.affiliation: Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.. Electronic address: jipfprince@gmail.com.
authors.forename: Jip F
authors.initials: JF
authors.lastname: Prince
authors.affiliation: Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
authors.forename: Maarten L J
authors.initials: ML
authors.lastname: Smits
authors.affiliation: Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
authors.forename: Gerard C
authors.initials: GC
authors.lastname: Krijger
authors.affiliation: Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
authors.forename: Bernard A
authors.initials: BA
authors.lastname: Zonnenberg
authors.affiliation: Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
authors.forename: Maurice A A J
authors.initials: MA
authors.lastname: van den Bosch
authors.affiliation: Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
authors.forename: Johannes F W
authors.initials: JF
authors.lastname: Nijsen
authors.affiliation: Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
authors.forename: Marnix G E H
authors.initials: MG
authors.lastname: Lam
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D005260:Female; D006695:Holmium / Q000627:therapeutic use*; D006801:Humans; D008113:Liver Neoplasms / Q000532:radiotherapy* / Q000556:secondary*; D008297:Male; D008863:Microspheres; D008875:Middle Aged; D011868:Radioisotopes / Q000627:therapeutic use*; D019275:Radiopharmaceuticals / Q000627:therapeutic use; D011879:Radiotherapy Dosage
chemical_list: D011868:Radioisotopes; D019275:Radiopharmaceuticals; D006695:Holmium