title: Hard beta and gamma emissions of 124I. Impact on occupational dose in PET/CT.
abstract: OBJECTIVE
  The hard beta and gamma radiation of 124I can cause high doses to PET/CT workers. In this study we tried to quantify this occupational exposure and to optimize radioprotection.
  
  
  METHODS
  Thin MCP-Ns thermoluminescent dosimeters suitable for measuring beta and gamma radiation were used for extremity dosimetry, active personal dosimeters for whole-body dosimetry. Extremity doses were determined during dispensing of 124I and oral administration of the activity to the patient, the body dose during all phases of the PET/CT procedure. In addition, dose rates of vials and syringes as used in clinical practice were measured. The procedure for dispensing 124I was optimized using newly developed shielding.
  
  
  RESULTS
  Skin dose rates up to 100 mSv/min were measured when in contact with the manufacturer's vial containing 370 MBq of 124I. For an unshielded 5 ml syringe the positron skin dose was about seven times the gamma dose. Before optimization of the preparation of 124I, using an already reasonably safe technique, the highest mean skin dose caused by handling 370 MBq was 1.9 mSv (max. 4.4 mSv). After optimization the skin dose was below 0.2 mSv.
  
  
  CONCLUSIONS
  The highly energetic positrons emitted by 124I can cause high skin doses if radioprotection is poor. Under optimized conditions occupational doses are acceptable. Education of workers is of paramount importance.
authors.affiliation: Department of Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands. gerrit.kemerink@mumc.nl
authors.forename: G J
authors.initials: GJ
authors.lastname: Kemerink
authors.forename: R
authors.initials: R
authors.lastname: Franssen
authors.forename: M G W
authors.initials: MG
authors.lastname: Visser
authors.forename: C J A
authors.initials: CJ
authors.lastname: Urbach
authors.forename: S G E A
authors.initials: SG
authors.lastname: Halders
authors.forename: M J
authors.initials: MJ
authors.lastname: Frantzen
authors.forename: B
authors.initials: B
authors.lastname: Brans
authors.forename: G J J
authors.initials: GJ
authors.lastname: Teule
authors.forename: F M
authors.initials: FM
authors.lastname: Mottaghy
mesh_terms: D001610:Beta Particles; D001822:Body Burden; D005720:Gamma Rays; D006801:Humans; D007457:Iodine Radioisotopes / Q000032:analysis*; D016273:Occupational Exposure / Q000032:analysis*; D049268:Positron-Emission Tomography; D014057:Tomography, X-Ray Computed; D014915:Whole-Body Counting
chemical_list: D007457:Iodine Radioisotopes