Scattered radiation from dental metallic crowns in head and neck radiotherapy.

We aimed to estimate the scattered radiation from dental metallic crowns during head and neck radiotherapy by irradiating a jaw phantom with external photon beams. The phantom was composed of a dental metallic plate and hydroxyapatite embedded in polymethyl methacrylate. We used radiochromic film measurement and Monte Carlo simulation to calculate the radiation dose and dose distribution inside the phantom. To estimate dose variations in scattered radiation under different clinical situations, we altered the incident energy, field size, plate thickness, plate depth and plate material. The simulation results indicated that the dose at the incident side of the metallic dental plate was approximately 140% of that without the plate. The differences between dose distributions calculated with the radiation treatment-planning system (TPS) algorithms and the data simulation, except around the dental metallic plate, were 3% for a 4 MV photon beam. Therefore, we should carefully consider the dose distribution around dental metallic crowns determined by a TPS.

[Clinical problems of alcoholics with a history of methamphetamine abuse].

The authors studied the clinical problems of alcoholics with a history of methamphetamine abuse as compared with alcoholics with no history. The samples were in- and out-patients of Kanagawa Prefectural Center of Psychiatry, Serigaya Hospital, from January to December 1992. This study covered 26 alcoholics who had abused methamphetamine from 1 to 40 years before, with an average age at admission was 43.5 years. This compared with a 50.4 year average for 89 alcoholics who had no history of methamphetamine abuse. Hepatitis C antibodies (HCVAb) were significantly more commonly observed in ex-methamphetamine abusers than in non-abusers (73.1% vs. 18.0%). Hepatitis B antigens (HBsAg) were no more common among abusers than non-abusers (0% vs. 2.2%). Blood transfusion history tended to be greater in ex-methamphetamine abusers than non-abusers (38.5% vs. 29.2%) but the difference did not reach conventional levels of statistical significance. Ex-abusers often wore tattoos (23.1%) whereas none of the non-abusers did, a significant difference. Significantly more ex-methamphetamine abusers were diagnosed as suffering from alcoholic hallucinosis than non-abusers (42.3% vs. 7.9%). As more ex-methamphetamine abusers than non-abusers were living alone (61.5% vs. 31.5%), were on welfare (61.5% vs. 23.8%), and living in skid-row areas (15.4% vs. 5.6%), the authors concluded that their living conditions were unstable.