The document discusses the evolution of radiation dose standards over time from the discovery of x-rays in 1895. Early researchers did not understand the biological effects of radiation and suffered injuries. Formal standards began in the early 1900s and continued to be refined through the 1900s based on new research findings. The standards set limits on radiation exposure for occupational workers and the general public based on balancing radiation risks and the benefits of practices involving radiation sources.

1. Radiation Protection Standard Pawitra Masa-at 4937092 SIRS/M March 2, 2007

2. A Brief History of Radiation Wilhelm Conrad Roentgen (above) discovered x rays in 1895 in Wurzburg, Germany. Also shown is his laboratory and a radiograph of a hand that he made in 1896 after his only public lecture on the discovery of x rays.

3. Antoine Henri Becquerel discovered radioactivity in 1896 in Paris. He is shown here in his laboratory.

4. A Brief History of Radiation In 1896, x-ray devices and radioactive materials were applied in physics, chemistry, and medicine. In the very early days, the users of x-rays were unaware That large radiation doses could cause serious biological effects They also had no instruments to measure the strength of the radiation fields. Instead, the calibration of x-ray tubes were based on the amount of skin reddening (erythema) produced when the operator placed a hand directly in the x-ray beam

5. It was common for the hands of the early radiologists to receive exceptionally high radiation doses. The loss of fingers, as shown in the photograph above, was sometimes the result.

6. Evolution of radiation dose standard In July 1896 , only one month after the discovery of x rays, a severe case of x-ray induced dermatitis was published In 1902 , the first dose limit of about 10 rad per day (or 3000 rad/year), was recommended. In 1903 , animal studies had shown that x rays could produce cancer and kill living tissue

7. Evolution of radiation dose standard In 1924 at a meeting of the American Roentgen Ray Society, Arthur Mutscheller recommended a “tolerance dose limit” for radiation workers (about 70 rem/year) & published in 1925 A tolerance dose was "assumed to be a radiation dose to which the body can be subjected without production of harmful effects.”

8. Evolution of radiation dose standard In 1930’s with the definition of exposure limits became quantitative. They were set to avoid deterministic effect such as skin erythema The first formal standard for protecting people from radiation sources The recommended limit on dose rate was expressed as 0.1 roentgen/day

9. Evolution of radiation dose standard In 1940’s The dose limits for radiation sources outside of the body (external sources) were augmented by a limit on the amount of radium a person could tolerate inside the body

10. Evolution of radiation dose standard After World War II In 1949 the United States, Canada, and Great Britain held a conference at Chalk River, and then published the Tripartite report A number of new concepts concerning the measurement of dose had been developed through animal studies. absorbed dose (rad) dose-equivalent (rem), relative biological effectiveness (RBE),

11. The Tripartite report also recommended standards for internal and external radiation protection, including A dose limit on… the bone-marrow  about 15 rem/year the skin  about 30rem/year Evolution of radiation dose standard

12. In 1950’s report of excess leukemia’s in Japan atom bomb survivors began to emerge established possibility of stochastic effects. in the early 1950s recommended standards for annual dose limits to the public. occupational dose limit = 5 rem/year public dose limit = 500 mrem/year Evolution of radiation dose standard

13. Evolution of radiation dose standard In 1960 , the Federal Radiation Council recommended an annual general public dose limit of 500 mrem/year In 1961 , The ICRP defined a system of dose control consisting of three parts : Justification of practices & expose situations. Optimization of protection of exposed persons. Limitation of individual dose and risk.

14. Evolution of radiation dose standard In 1977 ICRP (in report # 26) established dose limit for radiation protection based on risk assesment. In 1991 ICRP (in report # 60) revised these limit (based on analysis in BEIR V report 1990, UNSCEAR 1988)

15. Evolution of radiation dose standard

16. Estimates of Probability for cancer death Estimates of Probability for cancer death for period 1950-1985 changed for 4 reasons. The new dosimetry of Japanese data. More cancers observed over the year. Different radiation effects modeling. Different risk modeling accounting foe age.

17. Japanese - A bomb Survivors Most important single group studied because of their large number, the case with which hey have been followed, and the fact that people of all ages and both sexes recieveed a wide range of dose Approximately 150,000 to 220,000 people died within 4 months of bombing.

18. Japanese - A bomb Survivors 280,000 survived the immediate effect the two weapons, Of those: ~ 90,000 have been followed up carefully ~24,000 had died by late 1980’s (~5000 deaths were caused by cancer)

19. Type of Exposure Occupational exposure Medical exposure Public exposure Potential exposure

20. Type of Exposure Occupational exposure All exposures of workers incurred in the course of their work with the exception of exposures excluded from the Standards and exposures from practices or sources exempted by the Standards.

21. Type of Exposure Medical exposure Exposure incurred by patients as part of their own medical or dental diagnosis or treatment by persons voluntarily helping in the support and comfort of patients by volunteers in a programme of biomedical research involving their exposure.

22. Type of Exposure Public exposure Exposure incurred by members of the public from radiation sources, excluding any occupational or medical exposure and the normal local natural background radiation but including exposure from authorized sources and practices and from intervention situations.

23. Type of Exposure Potential exposure Exposure that is not expected to be delivered with certainty but that may result from an accident at a source or owing to an event or sequence of events of a probabilistic nature, including equipment failures and operating errors.

24. Dose limit Aim of Radiation Protection To limit the probability of stochastic effect Main concern are cancer, damage to embryo/fetus In the spirit of a International commission on Radiological Protection 1991’s report (ICRP 60) For occupationally exposed persons 20 mSv/year (whole body) average over 5 years with 50 mSv in single year For member of the public 1 msv/year

25. Comparison of dose limit (mSv/y) - 50 - 500 reminder 50 50 500 500 Hand & feet 50 50 500 500 skin 15 50 150 150 Lens for eye Equivalent dose 1 5 20 50 Effective dose No.60 No.26 No.60 No.26 public Occupation Term

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