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UNSCEAR ve BEIR V komitelerine göre ICRP çalışanlar için 8 x 10 -2 / sv yüksek dozlar ve doz hızları için ; 4 x 10 - 2 / sv düşük dozlar ve doz hızları için azla kanser görülme oranı belirlemişlerdir.
Genel popülasyon için biraz daha fazla risk hesaplanmıştır ( genç etkileşimler nedeniyle); yüksek dozlar ve doz hızları için 10 x 10 - 2 / sv 5 x 10 - 2 / sv düşük doz ve doz hızları için tahmin edilmektedir
İn-utero tanısal X-R alanlarda lösemi ve çocukluk çağı kanserlerinin ortaya çıkması 1.5 faktör kadar artmaktadır. Bu çocukluk çağı kanserlerinin az gözükmesi nedeniyle oldukça yüksek bir orandır. Ama Gy başına % 6 lık absulü riski yansıtır ki erişkin tahminlerinden farklı değildir
Best overall estimate of total radiation induced cancer mortality
a. 100 cases/rad/106 persons exposed (0.01%)
b. US Normal is 160,000 cases/106 persons (16%) -- for all cancers
Majority of our human data base
a. Japanese A-bomb survivors
b. Medically irradiated patients for both benign and cancer disease
c. medically internally administered radioactive materials
d. early radiologists and radiotherapist
Key Points continued
From L. J. Kleinsmith, Principles of Cancer Biology . Copyright (c) 2006 Pearson Benjamin Cummings. Types of DNA damage caused by ionizing radiation
Ionizing Radiation Carcinogenic effects discovered how? Occupationally exposed, patients exposed to diagnostic and therapeutic radiation and atomic bomb survivors Malignant epitheliomas of the skin - early X-ray and radium workers In 1895 and 1898 1914 - 108 cases were reported 1944 case of leukemias in radiologists increased and was then associated
25-30 years after whole body or trunk exposure
Increased incidence of leukemias
Saliary glands cancer
From L. J. Kleinsmith, Principles of Cancer Biology . Copyright (c) 2006 Pearson Benjamin Cummings. Cancer Incidence and death rates in atomic bomb survivors in Japan
From L. J. Kleinsmith, Principles of Cancer Biology . Copyright (c) 2006 Pearson Benjamin Cummings. Dose-response curves relating radiation exposure to cancer rates in atomic bomb survivors in Japan
1920s in a watch factory in Orange, New Jersey
Radium and mesothorium were painted on watch dials to illuminate the dials
Guess what happened
Another example is thorium - a contrast agent 2x and 6x for liver and leukemias
Childhood irradiation in head/neck - thymus incidence 83-fold greater rate
From L. J. Kleinsmith, Principles of Cancer Biology . Copyright (c) 2006 Pearson Benjamin Cummings. Sources of annual exposure to ionizing radiation in the United States
Risk of Dying from Various Activities Activity Cause of Death Risk of Death (per 10 6 per year) Smoking 1 pack/day all causes 3500 Canoeing for 20 h drowning 200 Traveling 1500 mi by car accident 40 Fishing drowning 10 Eating choking 8 5000 miles by plane accident 5 Chest X-ray cancer (radiation) 1 Living near nuclear cancer (radiation) <0.1 Power plant
Radyasyonun embryo ve fetus üzerindeki etkileri
Turai e.a. BMJ 328, march 2004: Medical response to radiation incidents and radionuclear threats. ‘ Events that expose people to radiation are rare, but the threat of radiation injury is increasing. Doctors should know how to recognize and manage suspected exposure or contamination’
Prevention is better dan healing! Especially for ‘preventable’ professional applications!
Radiation Carcinogenesis : The latent period; Dose response; malignancies in prenatally exposed children; Second tumors in radiotherapy patients. Risk estimates in the human; BEIR and UNSCEAR Committees; Calculations based on risk estimates.
· Heritable effects of radiation: Single gene mutations; Chromosome aberrations; Relative vs. absolute mutation risk; Doubling dose; Heritable effects in humans; Risk estimates for heritable effects.
Radiation effects in the developing embryo and fetus: Intrauterine death; Congenital abnormalities and neonatal death; Growth retardation; Microcephaly; Mental retardation; Dependence of the above effects on dose, dose-rate and stage in gestation; Human experience of pregnant women exposed to therapeutic doses.
Nuclide Total Mass of Nuclide Total Activity of Nuclide Daily Intake of Found in the Body Found in Body Nuclide Uranium 90 µg 1.1 Bq 1.9 µg Thorium 30 µg 0.11 Bq 3 µg Potassium-40 17 mg 4.4 kBq 0.39 mg Radium 31 pg 1.1 Bq 2.3 pg Carbon-14 95 µg 15 kBq 1.8 µg Tritium 0.06 pg 23 Bq 0.003 pg Polonium 0.2 pg 37 Bq 0.6 µg Natural Radioactivity in Your Body
Size of Critical Target DNA Human Cell Nucleus Yeast Cell
Comparative Radiosensitivity of Living Organisms Factors that Influence LD 50 Biological and Physical
Radiation Biology 30-100 Trillion Cells at Risk
Different Cell Types
Different Cell Cycle
Different Cell Targets
LD/50 = 4 Gy 4 Gy = 67 calories 67 calories = 3 ml sip of 60°C coffee