Basics of biological effects of ionizing radiation

Transcription

1 ANSN Regional Workshop on Medical Response to Radiological Emergency Handling Complex Situations 1-4 October 2013, Chiba, Japan Basics of biological effects of ionizing radiation Hideo Tatsuzaki, M.D., Ph.D. National Institute of Radiological Sciences (NIRS)

2 Contents (Tatsuzaki) What is an ionizing radiation Types of radiation Characteristics of radiation and radioactive materials Quantities and unit Usage of radiation Background Types of exposure Biological effect

3 What is ionizing radiation?

4 Radiation source radiation object

5 Atom Atom nucleus is made from protons and neutorons Electron Proton Neutron Helium atom (From Newton mook: The periodic table, 2007)

6 Ionization & Excitation Ionization Excitation electron Nucleus of atom proton + Neutron Electron -

7 Energy deposit

8 (from NIRS; Reference Document on Education and Self-Study Related to Radiation Medicine in Medical Education (Provisional Translation), Apr 2012)

9 alpha-ray & beta-ray Track of alpha-ray Track of beta-ray range range Just a nuclei of Helium at high energy Just a electron at high energy

10 Electron tracs (from ICRU report 86, Journal of ICRU 11(2), 2011)

11 Characteristics of radiation or radioactive materials

12 Radioactivity and radiation light Capacity to emit light Unit for Brightness Lux (lx) Unit for light source Candela (Cd) Radiation effect Sievert (Sv) radiation Radioactive material Capacity to emit radiation (radioactivity) Unit for racioactivity Bequrel (Bq)

13

14 (from NIRS; Reference Document on Education and Self-Study Related to Radiation Medicine in Medical Education (Provisional Translation), Apr 2012)

15 (from NIRS; Reference Document on Education and Self-Study Related to Radiation Medicine in Medical Education (Provisional Translation), Apr 2012)

16 (from NIRS; Reference Document on Education and Self-Study Related to Radiation Medicine in Medical Education (Provisional Translation), Apr 2012)

17 AIR TISSUE 2cm Alpha μ m 10s of meters m Beta Gamma mm

18 Origin of radiation Radioisotopes Sealded e.g. Ir-192 Accellerator Non-sealded e.g. Tc-99m X-ray generator

19 (from NIRS; Reference Document on Education and Self-Study Related to Radiation Medicine in Medical Education (Provisional Translation), Apr 2012) (( 独 ) 放射線医学総合研究所 : 医学教育における被ばく医療関係の教育 学習のための参考資料 ( 改訂 ) より )

20 Example of half life Radioisotpes Half life Sodium Na h Radon Rn days Iodine I days Cobalt Co years Strontium Sr years Cesium Cs years Radium Ra years Plutonium Pu k years Uranium U Bil years

21 Quantities and Units

22 Radioactivity, Radiation & Unit Radioactivity Capacity or nature to emit radiation Strength of radioactivity Materials emitting radiation (radioactive materials) Radiation Electro-magnetic wage or particle beam which conducts energy Radioactive materials Radioactivity (Bq) ((Ci)) Radiation Absorbed dose (Gy) Physical energy Equivalent dose(sv) Biological effect to tissue or organ( 等価 ) Effective dose(sv) Effect to whole body system( 実効線量 )

23 (from NIRS; Reference Document on Education and Self-Study Related to Radiation Medicine in Medical Education (Provisional Translation), Apr 2012)

24 (from NIRS; Reference Document on Education and Self-Study Related to Radiation Medicine in Medical Education (Provisional Translation), Apr 2012)

25 Where do they use radiation?

26 Usage of radiation Compound synthesis Modification of characteristics of plastic Maturation control Breeding Foods conservation X-ray examination Diagnosis of diseases Cancer therapy Non destractive test Check welding Measure thickness Gaugeing Tital or water current survey Chemical analysis Radioisotope battery Modified from Japan Atomic Energy Relations Organization

27 Radiations in daily life from space 0.39 msv/y from earth 0.48 msv/y from diet 0.29 msv/y Inhalation Radon gas etc msv/y We live in average annual dose of 2.4 msv of natural environmental radiation (1-10 msv/y) from UNSCEAR 2000; world average

28 Radiation in daily life Screening of stomach cancer upper GI 0.6mSv Chest X ray CT (computer tomography) 6.9mSv Screening by chest X ray 0.05mSv

29 (from )

30 Radiation protection and dose limit

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33 Types of exposure Acute exposure: receive radiation in a short time Chronic exposure: receive radiation in a protracted time Generally, acute exposure cause more effect than chorionic exposure with same absorbed dose

34 Measurements

35 Survey meter

36 Measurements Surface contamination (CPM Bq/cm 2 ) External exposure ambient dose equivalent (Sv)

37 Components of a human body nucleus tissue cell organ body

38 Radiation cell Cell damage by radiation Nucleus in cell chromosome Helical ladder structure after unwinding 放射線 Double helix of DNA in choromosome DNA=main target molecule

39 Structure and duplication of DNA Structure of DNA Duplication of DNA

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41 Colony formation Survival curve (from Hall EJ, Radiobiology for the radiologist, 2000)

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43 Dose rate effect (From EJ Hall, Radiobiology for the radiologist 5 th, 2000)

44 Dose rate effect of chromosomal aberrations Dicentric Dicentric and fragment chromosome observed on mouse exposed by long term exposure of low dose rate radiation (Yoshida, Hayata; Cross-over Research Report, 2009; From NIRS training school text) ( 放医研人材育成センターテキストより )

45 -- transformation -- A: A normal untransformed colony of hamster embryo cells. Contact inhibition+ B: A colony of radiationtransformed hamster embryo cells. (from EJ Hall, Radiobiology for the radiologist, 2000)

46

47 Basic Radiation Biology Concepts Bergonie J and Tribondeau L (1906) Cells that are immature and undifferentiated and actively dividing are more radiosensitive. (De quelques resultats de la radiotherapie et essai de fixation dune technique rationelle. CR Acad Sci. 1906;143:983) Stomach mucosa, basal layer of skin, stem cells 1. The more differentiated cells is, the less sensitive it is. 2. Actively proliferating cells are most sensitive. 3. Radio-sensitivity is proportional to duration of mitotic and development activity

48 END Hideo Tatsuzaki, M.D., Ph.D. National Institute of Radiological Sciences (NIRS)