Harry M. Cullings Radiation Effects Research Foundation Hiroshima and Nagasaki, Japan. EURADOS Winter School Milan, Italy February 11,

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1 Harry M. Cullings Radiation Effects Research Foundation Hiroshima and Nagasaki, Japan EURADOS Winter School Milan, Italy February 11,

2 Selection of Life Span Study cohort Available data Calculation of free-in-air kerma Calculation of shielding by Terrain Buildings Survivor s own body Adjustments of dose estimates for error EURADOS Winter School Milan, Italy February 11,

3 Population based Both sexes, all ages No selection due to medical or occupational conditions that might cause bias Size ~120,000 ~94,000 in cities during bombings ~2/3 in Hiroshima, 1/3 in Nagasaki Extensive attention to dosimetry Rigorous follow-up Sub-cohort clinical study: Adult Health Study (AHS) EURADOS Winter School Milan, Italy February 11,

4 Identify all persons in 1950 national census who had been in Hiroshima or Nagasaki during bombing Create a Master Sample of those still living in H or N and meeting other criteria Form LSS from Master Sample by random sampling Include all within 2.5 km of bomb Age and sex-matched random sample of those between 2.5 and 10 km EURADOS Winter School Milan, Italy February 11,

5 Key data such as sex and date of birth were taken from various survey instruments Radiation Questionnaire, Migration Questionnaire Master Sample Questionnaire (MSQ) MSQ had much additional information Location and shielding at time of bomb Injuries Medical symptoms potentially related to radiation exposure Occupation Residential history EURADOS Winter School Milan, Italy February 11,

6 Background: Digital Map 25000, Geographical Survey Institute of Japan, Circles of black dots at 2 and 3 km from hypocenter. Color key, in order of drawing, starting with bottom layer: dark gray = unknown dose, pink < 5 mgy, purple 5 to 100, blue 100 to 200, green 200 to 500, yellow 500 to 1,000, orange 1,000 to 2,000, red > 2,000. EURADOS Winter School Milan, Italy February 11,

7 Collected on ~100% of those < 1.6 km in Hiroshima and < 2 km in Nagasaki ~42% of those between 1.6 and 2 km in Hiroshima Details of location and shielding at time of bomb Structural shielding For some survivors in Nagasaki, terrain shielding EURADOS Winter School Milan, Italy February 11,

8 Align ~15,000 neighborhood diagrams from survivors shielding histories to orthophoto mosaic much work! EURADOS Winter School Milan, Italy February 11,

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10 Type of Shielding No shielding history or no DS02 model Shielding history and DS02 model Dose Dose not Dose Dose not estimated estimated estimated estimated Inside 44,844 5,548 House 12,858 0 School Other wooden building Fact ory 205 (Hiroshima) Concrete 696 building 652 (Nagasaki) Outside 19,919 In open 415* 1,139 0 Near building 3,104 1 Near small hill No shielding information 2, Not in city 26,580 0 Column totals 93,719 7,062 19,532 8 Total 120,321 *in open at < 2 km without thermal injury to exposed skin EURADOS Winter School Milan, Italy February 11,

11 Prompt Source Delayed Source Transport Hypocenter Shielding EURADOS Winter School Milan, Italy February 11,

12 Free-In-Air fluences CF FIA kerma TF Shielded kerma CF Shielded fluences Organ fluences CF Organ dose EURADOS Winter School Milan, Italy February 11,

13 fia kerma, Gy 1000 Hiroshima 1000 Nagasaki ground distance, m ground dis tance, m neutron gamma neutron gamma EURADOS Winter School Milan, Italy February 11,

14 -ray dose in Nagasaki is ~ 3x Hiroshima at closer distances ranging down to ~ 2x Hiroshima at long distances Neutron dose in Nagasaki ranges from 44% to 68% of that in Hiroshima depending on distance The neutron/ -ray dose ratio is considerably less for internal organs due to strong attenuation of neutrons in the body EURADOS Winter School Milan, Italy February 11,

15 % % 10 Hiroshima 10 Nagasaki ground distance, m ground distance, m fia kerma marrow dose shielded kerma colon dose fia kerma marrow dose shielded kerma colon dose EURADOS Winter School Milan, Italy February 11,

16 Contours shown are at elevations of 0, 5, 10, 15, 20, 30,, 90, 100, 120,, 320, 340 m (by 5 m intervals to 20 m, 10 m intervals to 100 m, 20 m intervals to 340 m). The white circle has radius 2 km. EURADOS Winter School Milan, Italy February 11,

17 3 km 2 km 3 km 2 km Key: terrain -ray transmission factor < blue green yellow orange EURADOS Winter School Milan, Italy February 11,

18 Persons inside houses have 9-parameter data on floor occupied, slant penetration distance, etc. Persons outside but near buildings have globe data on portions of solid angle subtended by buildings in various directions relative to bomb Model house cluster created for DS86 Various positions inside and outside of houses were calculated for various azimuthal orientations relative to bomb and recalculated for DS02 Results in ~1,200 shielding calculations Methods are used to match a survivor s data to a particular calculation EURADOS Winter School Milan, Italy February 11,

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22 DS02 added a school model larger rooms and fewer interior walls than houses DS02 factory model Two types of buildings Work benches and machine tools Worker is assumed to be standing or sitting until arrival of blast wave (fluences at 1 m ht) Then lying on ground (fluences at 15 cm ht) EURADOS Winter School Milan, Italy February 11,

23 HOB horizon point elevation survivor s elevation 12 m Adjusted ground distance hypocenter EURADOS Winter School Milan, Italy February 11,

24 Based on 1983-vintage stylized phantoms Infant, child, adult only No pregnant woman (use non-pregnant uterine dose currently) 15 organs: bladder, brain, breast, colon, eye lens, liver, lung, ovaries, pancreas, red bone marrow, skeleton, stomach, testes, thyroid, uterus New binational working group formed in 2015 to look at revised organ dose calculations EURADOS Winter School Milan, Italy February 11,

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26 Gy No shielding Average house shielding Ground distance, m Human LD 50 ICRP annual limit for workers Average annual dose from natural background, Japan (excluding radon) EURADOS Winter School Milan, Italy February 11,

27 N ,671 in-city members of LSS with known doses Weighted absorbed colon dose, mgy, neutron wt = 10 EURADOS Winter School Milan, Italy February 11,

28 Classical or measurement error: D obs = D true + error RERF conventionally assumes 35% lognormal error Due primarily to inaccuracy of survivor recall regarding location and shielding Leads to biased regression estimates if not corrected Berkson or grouping error: D true = D obs + error Typically less of a problem than measurement error Substantial in RERF data due to use of a limited number of shielding models by DS02, etc. Considerably larger for those without shielding histories EURADOS Winter School Milan, Italy February 11,

29 RERF currently uses a regression calibration & substitution method based on the 35% lognormal error assumption i.e., replace D obs with E(D true D obs ) Dose uncertainty is an active area of RERF statistical research with external collaborators Especially use of biodosimetry EURADOS Winter School Milan, Italy February 11,

30 Correction Factors Shielded kerma, Gy Hiroshima Nagasaki Hiroshima Nagasaki EURADOS Winter School Milan, Italy February 11,

31 DS86 and DS02 Reports available online at Cullings HM et al. Dose estimation for the atomic bomb survivor studies: its evolution and present status. Radiation Research 166, Cullings HM et al. DS02R1: Improvements to atomic bomb survivors input data and implementation of Dosimetry System 2002 (DS02) and resulting changes in estimated doses. Health Physics, to appear EURADOS Winter School Milan, Italy February 11,