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RADIATION PROTECTION IN RADIOTHERAPY. IAEA Training Material on Radiation Protection in Radiotherapy. Part 3: Radiation Biology PRACTICAL EXERCISE. Objectives of Part 3. To understand the various effects of radiation on human tissues
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RADIATION PROTECTION IN RADIOTHERAPY IAEA Training Material on Radiation Protection in Radiotherapy Part 3: Radiation BiologyPRACTICAL EXERCISE
Objectives of Part 3 • To understand the various effects of radiation on human tissues • To appreciate the difference between high and low dose; deterministic and stochastic effects • To gain a feel for the order of magnitude of dose and effects • To appreciate the risks involved in the use of ionizing radiation as a starting point for a system of radiation protection Part 3, Practical 1
Part 3: Radiation Biology IAEA Training Material on Radiation Protection in Radiotherapy Practical 1: Calculation of cancer incidence
Contents + Objective • Appreciate the order of magnitude of radiation induced cancer for relatively small additional long term exposures • Perform a simple calculation using information given in the lecture Part 3, Practical 1
How many additional cancers would we expect in a population of 1000 people exposed to 5mSv per year for 20years? …and how does this compare with the normal cancer mortality rate? Part 3, Practical 1
Assumptions • Risk of cancer mortality is 0.05 per Sv (as per ICRP report 60 for low dose rate exposure of the total population) • 1,000 people are exposed to 5 mSv/y for 20 y Part 3, Practical 1
Questions? Let’s get started... Part 3, Practical 1
Example for Risk Calculation • Expected additional cancer deaths is 0.05 [cancers/Sv]x0.005[Sv/y]x20[y]x1,000[people] = 5 additional cancer deaths due to radiation Part 3, Practical 1
Example for Risk Calculation • Expected additional cancer deaths is 5 additional cancer deaths due to radiation • General population: 23% of all deaths due to cancer • Therefore have 230 expected cancer deaths due to other causes... • Can we pick 5 additional ones??? Part 3, Practical 1
Other interesting points... • This assumes stochastic effects only • Radiation induced cancer are not distinguishable from other cancers (at least not at present) • Illustration of the difficulty of producing good epidemiological evidence • Calculations become more complex for individual tissue exposures vs. whole body exposures Part 3, Practical 1