Biological Effects of Radiation:Types Short note for written examination. Biological Effects of Radiation: The harmful effects caused to human beings and other living beings due to their exposure to radiation is called biological effects of radiation/hazards of radiation. Deterministic Effects: A deterministic effect is one “which increases in severity with increasing absorbed dose in affected individuals.” These effects appear at high dose > 0.5Gy and generally result from cell death. Stochastic Effects: Stochastic effect is one in which “the probability of occurrence increases with increasing absorbed dose rather than its severity.” Somatic Effects: The radiation effects, produced in an exposed individual during his lifetime are called somatic effects Radiation injuries that produced change in somatic cells (all the cells of the body except the reproductive cells) Genetic Effects: The radiation effects produced in the successive generation of the exposed individual are called generic effect Acute Effects: Effects that are seen within minutes, days, or weeks of irradiation are termed as acute effects. Late Effects: Late effects occur predominantly in slow proliferating tissue, and appear after delay of months or years from irradiation.

1. Biological Effects of Radiation:Types
MD. MOSTAK AHMED
B.Sc. RIT(Enrolled)
DMT(Radiology & Imaging)
Deterministic Effects
Stochastic Effects
Somatic Effects
Genetic Effects
Short Answer for written examination
Acute Effects
Late Effects

2. Biological Effects of Radiation
The harmful effects caused to human beings and other living
beings due to their exposure to radiation is called biological
effects of radiation/hazards of radiation.
√ Biological effects on living cells may result in three outcomes :
i. Injured or damaged cells repair themselves, resulting in no residual damage.
ii. Cells die, much like millions of body cells do everyday, being replaced through
normal biological process.
iii. Or the damage is not repaired or misrepaired, so the cell is altered. This
alteration eventually lead to cancer.
Edited & Compiled: Md. Mostak Ahmed, B.Sc RIT, Batch-7

3. Types of Radiation Effects
Deterministic (Non – stochastic) Effects
A deterministic effect is one “which increases in severity with increasing absorbed dose in
affected individuals.” These effects appear at high dose > 0.5Gy and generally result from
cell death.
Deterministic effects are characterized by a Threshold Dose, below which the effect does
not occur. The threshold may be very low and may vary from person to person.
However once the threshold those has been exceeded, the severity increases with dose.
Examples of deterministic effects (doses are given as absorbed dose);-
▪ Skin erythema: 2-5 Gy
▪ Irreversible skin damage: 20-40 Gy
▪ Epilation: 2-5 Gy
▪ Sterility: 3-4 Gy in women and 5 Gy in men
▪ Cataracts: 0.5 Gy
▪ Lethality(Whole body): 3-5 Gy
▪ Fetal Abnormality: 0.1-0.5 Gy
Edited & Compiled: Md. Mostak Ahmed, B.Sc RIT, Batch-7

4. Stochastic Effects
Stochastic effect is one in which “the probability of occurrence increases with
increasing absorbed dose rather than its severity.”
Stochastic means random and the severity of stochastic effect is independent of the
radiation dose. As the radiation dose increases, the chance of the effect occurring
increases.
It has no threshold dose, may occur at low doses and the effect may be seen only
laterr period (10 to 13 years). Such as DNA mutation that can occur at any radiation
dose.
Stochastic effects, such as malignancy, are “all or none.” The cancer produced by a
small dose is the same as a cancer produced by a large dose, but the frequency of
occurrence is less with the smaller dose.
Depending on the type of cell injured by radiation the biological effects are:
1. Somatic Effects
2. Genetic Effects
Edited & Compiled: Md. Mostak Ahmed, B.Sc RIT, Batch-7

5. Somatic Effects
● The radiation effects, produced in an exposed individual during his lifetime are called somatic
effects
● Radiation injuries that produced change in somatic cells (all the cells of the body except the
reproductive cells)
● Major somatic effects of radiation exposure include the induction of cancer, leukaemia and
cataracts
● These change, however, are not transmitted to future generations
Genetic Effects
● The radiation effects produced in the successive generation of the exposed individual are called
generic effect
● Ionizing radiation damages the genetic material in reproductive cells and results in nutritions that
are transmitted from generation to generation
● Mutation: Any change in chromosomes, their genes and their DNA include an array of change in
DNA, such as deletion, rearrangement, breakage in the sugar phosphate backbone and base
alteration
● Doubling dose: The dose of radiation expected to double the number of the genetic mutation in a
generation
● Genetic defects are not seen in the irradiated person but are passed onto future generations
● Radiation injuries that produce change in genetic cells do not affect the health of the exposed
individual. Instead, radiation induced mutation affect the health of the offspring
Edited & Compiled: Md. Mostak Ahmed, B.Sc RIT, Batch-7

6. Depending on the time of appearance of effects after exposure, effects are: Acute/Late
Acute Effects
▪ Effects that are seen within minutes, days, or weeks of irradiation are termed as
acute effects.
▪ Acute effects are associated with large amounts of radiation absorbed in a short
time and usually result from death of a large number of cells
▪ When human body receives a high radiation dose of more than 1Sv in a short time,
acute radiation effects may occur such as nausea, vomiting, fatigue, and epilation.
The result may be fatal if the radiation dose is 10 Sv or more with no suitable
medical treatment.
▪ Acute damage is repaired and may be completely reversible.
Late Effects
▪ Late effects occur predominantly in slow proliferating tissue, and appear after delay
of months or years from irradiation.
▪ Late effects are associated with small amount of radiation absorbed repeatedly over
a long period.
▪ It includes, induction of cancer, birth abnormalities and genetic effects.

7. Thank You
Hi, I’m Md. Mostak Ahmed, a B.Sc. RIT student from IHT Mohakhali (Batch-7) under Faculty of
Medicine, University of Dhaka.
I’ve completed Diploma in Medical Technology (Radiology & Imaging) from govt. IHT Sylhet and passed final
examination in 2018 under The State Medical Faculty of Bangladesh. This degree is enough to practice as Radiographer
in Bangladesh and currently i’m working with Popular Diagnostic Ltd. After completing B.Sc. i’m hoping to enroll in a
world class university for PhD/Masters and finally become an academic/researcher. Please keep me in your prayer.
About Me