title: [166Dy]Dy/166Ho hydroxide macroaggregates: an in vivo generator system for radiation synovectomy.
abstract: Radiation synovectomy is an effective treatment in patients suffering from inflammatory-rheumatoid and degenerative joint diseases. The aim of this work was to examine the feasibility of preparing dysprosium-166 (166Dy)/holmium-166(166Ho) hydroxide macroaggregates ([166Dy]Dy/166Ho-HM) as an in vivo generator for radiation synovectomy evaluating whether the stability of 166Dy-HM and 166Ho-HM complexes is maintained when the daughter 166Ho is formed. The Monte Carlo (MCNP4B) theoretical depth dose profile for the in vivo [166Dy]Dy/166Ho generator system in a joint model was calculated and compared with that produced by 90Y, 153Sm and 166Ho. 166Dy was obtained by neutron irradiation of enriched 164Dy2O3 in a Triga Mark III reactor. Macroaggregates were prepared by reaction of [166Dy]DyCl3 with 0.5 M NaOH in an ultrasonic bath. [166Dy]Dy/166Ho-HM was obtained with radiochemical purity >99.5% and with the majority of particles in the 2-5 microm range. In vitro studies demonstrated that the radio-macroaggregates are stable in saline solution and human serum without a significant change in the particle size over 14 d, suggesting that no translocation of the daughter nucleus occurs subsequent to beta- decay of 166Dy. Biological studies in normal rats demonstrated high retention in the knee joint even 7 d after [166Dy]Dy/166Ho-HM administration. The Monte Carlo (MCNP4B) theoretical depth dose profiles in a joint model, showed that the in vivo [166Dy]Dy/166Ho generator system would produce 25% and 50% less radiation dose to the articular cartilage and bone surface, respectively, than that produced by 90Y or pure 166Ho in a treatment with the same therapeutic dose to the synovium surface. Despite that 153Sm showed the best depth dose profile sparing doses to healthy tissues, the use of 166Dy could provide the advantage of being applied in patients that cannot be reached within a few hours from a nuclear reactor and to produce less radiation exposure to the medical personnel during the radiopharmaceutical administration.
authors.affiliation: Departamento de Materiales Radiactivos, Instituto Nacional de Investigaciones Nucleares, Km. 36.5 Carretera Mexico-Toluca, Ocoyoacac, Estado de Mexico, CP 52045, Mexico. gff@nuclear.inin.mx
authors.forename: G
authors.initials: G
authors.lastname: Ferro-Flores
authors.forename: O
authors.initials: O
authors.lastname: Hernández-Oviedo
authors.forename: C
authors.initials: C
authors.lastname: Arteaga de Murphy
authors.forename: J I
authors.initials: JI
authors.lastname: Tendilla
authors.forename: F
authors.initials: F
authors.lastname: Monroy-Guzmán
authors.forename: M
authors.initials: M
authors.lastname: Pedraza-López
authors.forename: K
authors.initials: K
authors.lastname: Aldama-Alvarado
mesh_terms: D000818:Animals; D001172:Arthritis, Rheumatoid / Q000532:radiotherapy; D004419:Dysprosium / Q000737:chemistry / Q000302:isolation & purification / Q000493:pharmacokinetics* / Q000627:therapeutic use; D005240:Feasibility Studies; D006695:Holmium / Q000737:chemistry / Q000302:isolation & purification / Q000493:pharmacokinetics* / Q000627:therapeutic use; D006801:Humans; D007553:Isotope Labeling / Q000379:methods*; D007592:Joint Diseases / Q000532:radiotherapy; D007596:Joints / Q000378:metabolism*; D046911:Macromolecular Substances / Q000138:chemical synthesis / Q000302:isolation & purification / Q000627:therapeutic use; D008297:Male; D008657:Metabolic Clearance Rate; D009928:Organ Specificity; D011868:Radioisotopes / Q000737:chemistry / Q000302:isolation & purification / Q000493:pharmacokinetics* / Q000627:therapeutic use; D019275:Radiopharmaceuticals / Q000138:chemical synthesis / Q000302:isolation & purification / Q000493:pharmacokinetics* / Q000627:therapeutic use; D051381:Rats; D014018:Tissue Distribution
chemical_list: D046911:Macromolecular Substances; D011868:Radioisotopes; D019275:Radiopharmaceuticals; D004419:Dysprosium; D006695:Holmium