title: Time- and dose-related changes in the thickness of skin in the pig after irradiation with single doses of thulium-170 beta particles.
abstract: Time-related changes in skin thickness have been evaluated in the pig using a noninvasive ultrasound technique after exposure to a range of single doses of 0.97 MeV beta particles from (170)Tm plaques. The reduction in relative skin thickness developed in two phases; the separation into two phases was statistically justified only after 120 Gy (P = 0.04). The first phase was between 12 weeks and 24 weeks after irradiation. No further changes were seen until 48-60 weeks after irradiation, when a second phase of skin thinning was observed. No further changes in relative skin thickness were seen in the follow-up period of 104 weeks. The timing of these phases of relative skin thinning was totally independent of the radiation dose; however, the severity of each phase of radiation-induced skin thinning was related to the dose. The pattern of changes was similar to that reported previously after irradiation with 2.27 MeV beta particles from (90)Sr/(90)Y, but the degree of dermal thinning was less for a similar skin surface dose. From a comparison of the depth-dose distribution of the beta particles from the two radionuclides, it was concluded that the target cell population responsible for both the first and second phase of skin thinning in pig skin after irradiation may be located at approximately 800 microm depth. This corresponds to an area in the reticular dermis in pig skin and may be the appropriate site at which to measure the average dose to the dermal tissue.
authors.affiliation: Normal Tissue Radiobiology Research Group, Research Institute (University of Oxford), Churchill Hospital, Oxford OX3 7LJ, United Kingdom.
authors.forename: M
authors.initials: M
authors.lastname: Rezvani
authors.forename: J W
authors.initials: JW
authors.lastname: Hopewell
authors.forename: J H
authors.initials: JH
authors.lastname: Wilkinson
authors.forename: S
authors.initials: S
authors.lastname: Bray
authors.forename: G M
authors.initials: GM
authors.lastname: Morris
authors.forename: M W
authors.initials: MW
authors.lastname: Charles
mesh_terms: D000818:Animals; D001284:Atrophy / Q000000981:diagnostic imaging / Q000209:etiology; D001610:Beta Particles / Q000009:adverse effects*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D011868:Radioisotopes / Q000009:adverse effects*; D011874:Radiometry; D012867:Skin / Q000000981:diagnostic imaging / Q000473:pathology* / Q000528:radiation effects*; D013326:Strontium Radioisotopes / Q000009:adverse effects; D013552:Swine; D013932:Thulium / Q000009:adverse effects*; D013997:Time Factors; D014463:Ultrasonography; D015021:Yttrium Radioisotopes / Q000009:adverse effects
chemical_list: D011868:Radioisotopes; D013326:Strontium Radioisotopes; D015021:Yttrium Radioisotopes; D013932:Thulium