Deterministic effect
| Deterministic effect |
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| See also |
Deterministic effects are the effects of radiation on exposed individual that have a threshold dose value below which they do not appear. For example, cataract, blood count changes, erythema, infertility as given in. Above the threshold dose value, the severity of the deterministic effect is increased as the dose is increased. This may be included by either acute or chronic exposure[1].
The impacts of radiation exposure from nuclear power are primarily stochastic. Even in the accident at Chernobyl, relatively few workers received high enough acute radiation doses to cause either death within a few months or other deterministic effects. Much larger populations were exposed to lower doses. The predicted appearance of cancer in these populations is delayed, typically by more than 10 years after the time of exposure and it is not possible to identify specific individual victims[2].
Types of deterministic effects
Radiation effects are classified as:
- Early effects
- Late effects
Early effects have a threshold dose, above which it will be seen, whereas late effects have no dose limits. Early deterministic effect occurs every time a certain radiation dose level or threshold dose exceeded. Therefore, the risk of deterministic effects attributed to the exposures likely to be encountered in diagnostic nuclear medicine procedures is nil. Deterministic effects include reddening of the skin, sterility, cataracts, radiation sickness, and even death if the dose is high-dose levels exceed. Late effects happen only to a certain percentage of individuals in a group that is exposed to a given hazard. The principal stochastic effect from radiation doses associated with diagnostic nuclear medicine is cancer. Hereditary effects manifested in the offspring of exposed individuals are less likely. Incident of cancer in radiation workers is not more than in general population[3].
Absorbed doses in radiology
To understand the significance of deterministic effects in diagnostic radiology, it is necessary to know the dosed patients or staff might receive. In general the dose are no more than a few tens of mGy, indicating little significance of threshold does in diagnostic radiology. Computed tomography scans can result in relatively high eye doses in the region of several tens of mGy. Although this may be much less than the threshold dose, the possibility of the patient having several scans over their lifetime linked to the cumulative nature of the effect makes it good practice to use techniques that will minimize the dose to the lens[4].
Footnotes
References
- Allisy-Roberts P.J., Williams J., (2007),Farr's Physics for Medical Imaging, Elsevier Health Sciences, Edinburgh.
- Bodansky D., (2007), Nuclear Energy: Principles, Practices, and Prospects, Springer, Seattle.
- Prakash D., (2014), Nuclear Medicine: A Guide for Healthcare Professionals and Patients, Springer, Mumbai.
- Sureka C.S., Armpilia Ch., (2017), Biology for Medical Physicists,CRC Press, New York.
Author: Klaudia Piotrowska
