The air dose outside of buildings due to primary and scattered radiation released by atomic bombs in Hiroshima and Nagasaki was estimated as a function of distance from the hypocenter. Neutron dose was estimated from 6oCo activity in iron imbedded in concrete and gamma dose from thermoluminescence in bricks and tiles.The precision (coefficient of variation) of estimation was less than 0.11 for y-rays and less than 0.15 for neutrons. The results as compared with York's values(l) show only a minor difference for y and agree with that for neutrons in Nagasaki, but a large difference of approximately 50 per cent for neutrons and 30-70 per cent for y-rays at distances from 500 to 1500 m from the hypocenter for Hiroshima. Therefore the total air dose was almost equal to York's value in Nagasaki, but less than half in Hiroshima.
We evaluated the predictive relevance of several biomarkers on the survival of patients with stage III colorectal cancer treated with adjuvant chemotherapy of oral fluoropyrimidines. This was a multicenter phase II trial on adult patients with histologically confirmed resected stage III (Dukes' C) colorectal cancer. Patients received oral doxifluridine (800 mg/m2/day) in 3 divided doses, or oral uracil/tegafur (UFT) (400 mg/m2/day) in 2 divided doses for 5 days, every 7 days for 12 months with a 5-year follow-up. Outcome measures were disease-free survival and tissue markers [thymidine phosphorylase (TP), dihydropyrimidine dehydrogenase (DPD) protein levels and TP, DPD, thymidylate synthase (TS) and orotate phosphoribosyltransferase (OPRT) mRNA levels in tumor samples and TS tandem-repeat type in blood samples]. There was a significant association between the intratumoral TP/DPD enzyme ratio and disease-free survival when the model included the drug, the parameter and the interactions between them [hazard ratio (HR)=2.76; P=0.00469]. The 5-year disease-free survival rate was statistically significantly higher in patients with high TP/DPD ratios [median ≥2.63: 71.9%; 95% confidence interval (CI) 61.4-80.0] compared to patients with low TP/DPD ratios (<2.63: 57.0%; 95% CI 46.3-66.3) (log-rank P=0.0277) following adjuvant therapy with oral fluoropyrimidines. No significant association was observed between the intratumoral TP/DPD enzyme ratio (cut-off value 2.0) and the disease-free survival rate in the doxifluridine group; primary endpoint (log-rank P=0.6850). The magnitude of the intratumoral TP/DPD enzyme ratio may be a potential indicator for the individualization of postoperative adjuvant chemotherapy with oral fluoropyrimidines for stage III colorectal cancer.
Epidemiological study of carcinogenesis of thorotrast was made in the following three ways of survey. 1) Prospective study: Of 147 thorotrast patients surveyed, 3 cases of liver cancer (cholangiocareinoma), 2 cases of liver cirrhosis and 1 case of leukemia were found, while, of 1,678 of non injected cases, 1 case of leukemia, 5 cases of liver cirrhosis and no liver cancer occurred more frequently in the thorotrast group than in controls.2) Retrospective study: Of 466 liver cancer patients surveyed, 4 or 0.85% had thorotrast shadow in the roentgenogram of the upper abdomen , while, of 1,938 controls, 1 or 0.07% the thorotrast shadow. Statistically, the thorotrast maintaining rate is higher in liver cancer patients than in contols.3) Autopsy case study: Of 38 autopsied cases of thorotrast, 21 were primary liver malignancy, which consisted of 4 hepatomas (19%), 14 cholangiocarcinomas (67%) and 3 endotheliomas (14%). As compared with the autopsy cases of Japanese, cholangiocarcinoma and endothelioma are extremely frequent in thorotrast cases with a statistically significant difference.Radiation carcinogenesis in man has been studied by the present research group since 1961. Of the results obtained, relationship between medical external irradiation and consequent human cancer was already published elsewhere in 1963 (Takahashi et al.1). The purpose of this paper is to describe a statistical study on carcinogenesis in patients who were irradiated for a long time by the internally introduced thorotrast, colloidal thorium dioxyde (Oka) ,2 for the diagnostic aid.
The gamma-ray dose from the radioactivity induced in soil and building materials by neutrons was estimated on the basis of the experimental data. l'he chemical compositions of soil and building materials collected from Hiroshima and Iiagasaki were determined by an activation analysis. It was found that 24Xa and 5"Mn contributed mainly to the gamma-ray dose from the radioactivity induced in soil. The dose received by a person who entered the hypocenter area in Hiroshima one day after the bombing and remained there 8 fir would have been 3 rads. The doses at distances of 500 m and I000 m from the hypocenter in Hiroshima were 18% and 0.07% respectively, of that at the hypocenter. The accumulated gamma-ray dose from immediately after the explosion of the A-bombs to infinity was about 80 rads at the hypocenter in Hiroshima, and about 30 rads in Nagasaki.
The broad-beam attenuation coefficients for lead, iron, heavy concrete and ordinary concrete were evaluated using the X-ray beams from a 32 MeV betatron, a 3 1 iMeV betatron and a 6 lMeV linear accelerator for the purpose of the design of the protective shielding to be placed around high enexgy accelerators. Attenuations in these materials were determined by measuring the ionization in a cavity in a water phantom behind various thicknesses of materials.The variation in tenth-value thickness with field size for these materials is discussed on the basis of data obtained from the attenuation measurements. The tenth-value thickness for these materials is shown as a function of X-ray energy. The tenth-value thicknesses determined using the three X-ray generators are compared.
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