Week 8 Flashcards
What is another Term for ‘Radiation Life-Shortening and how can it be observed’?
- Radiological ageing
2. Observed by comparison of mortality curves of irradiated and non irradiated animals or humans?
How does radiation reduce remaining life expectancy for acute exposure and protracted exposure?
1-5% reduction in remaining life expectancy per Sv for acute exposure
< 1% per Sv for protracted exposure
Other than animals, what are two human populations, in which life shortening has been evident?
- US radiologists
2. And the A-bomb survivors
Do reductions in life expectancy, occur due to radiation induced cancer? If not why?
No- life shortening is not attributable to cancer alone, also due to age specific diseases.
Where do we get our information regarding radiocarcinogenesis?
- Nuclear Weapons
- Medical Radiotherapy
- Medical Imaging
- Natural Environment
What is the Mouse Study? What did it show?
Mice were irradiated with differing amounts of radiation at 7 days of age.
The graph clearly shows an increased relative risk with increased radiation dose.
Is there much information on the effects of IR on the developing embryo?
Human data is scare for studying the effects, most data comes from mice.
What can irradiation during development of the embryo cause? (name all 4).
- Pre- and neo natal death
- growth retardation
- abnormalities
- post-natal induction of cancer
What are the in Utero Effects of radiation?
- As cells divide rapidly during gestation. Radiation damage will express itself early and embryos are more radiation sensitive than adults.
- They have an increased chance of these effects occurring due to their increased life expectancy (babies have longer to lyf to live)
What is the ICRP? What are their two recent reports?
International Commission on Radiological Protection.
- ICRP report 77
- ICRP 90 (Addresses biological effects of prenatal irradiation)
What does the nature and magnitude of the effect depend on? (in embryonic radiation)
Three stages;
- The preimplantation Stage
- The organogenesis stage
- The fetal Stage
What is the Preimplantation stage? What amount of dose can kill?
- is the period from conception until the fertilised egg attaches to uterus wall (0-9days).
- Pre natal death is a significant risk.
- 0.05 Gy can kill (mouse data) LD50/30 - 1 Gy
In the preimplantation stage, is the embryo survives, will it develop normally?
Yes. Radiation is an ‘all or nothing’ effect.
What is organogenesis? When does this occur?
- The stage in which the fetus develops major organs. Peak incidence of abnormalities occur early in organogenesis.
- occurs at 10days-6 weeks
Throughout organogenesis, which organ system is most sensitive?
The Central Nervous System
