Biological Effects of Radiation (Types and Description)

Types, Description, and Explanation of Biological Effects of Radiation

1. BIOLOGICAL d
EFFECTSOF A
RADIATION 4%

By: THE WONDERS OF
MARMALADY

2. RADIATION

-Radiation can be defined as the transmission of
energy from a body in the form of waves or
particles.

Examples includes heat or light from the sun,
microwaves from an oven, X rays from an x-ray
tube, and gamma rays from radioactive elements.

3. + Radiation is not only emitted during radiation
therapy, but also from microwaves, cell phones,
computers, and so on.

+ Radiation is a type of energy that occurs
naturally and can even be man- made.

+ When the radiation is from the Sun or outer
space, then it is called cosmic radiation, and
when it comes from minerals in the Earth it is
called terrestrial radiation.

4. + 13% of all radiation present is man-made
while 12% is produced by X-ray and MRI
machines, and 1% is produced by nuclear
industries.

« Man-made radiation is more harmful as
compared to natural ones because it is
more concentrated.

5. TYPES OF RADIATION
(ON THE BASIS OF ENERGY OF
RADIATED PARTICLES)

6. TYPES OF
RADIATION

Radiation is often categorized

as either ionizing or non-
ionizing depending on the
energy of the radiated
particles.

7. IONIZING RADIATION

¢ lonizing radiation is radiation that carries enough

energy to detach electrons from atoms or
molecules, thereby ionizing them.

e lonizing radiation carries more than 10 eV energy,
which is enough to ionize atoms and molecules,
and break chemical bonds.

8. IONIZING RADIATION

e lonizing radiation consisting of
particles, X-rays, or gamma rays with

sufficient energy to cause ionization
in the medium through which it
passes.

9. IONIZING RADIATION

10. NON-IONIZING RADIATION

¢ Non-ionizing radiation refers to any type of

electromagnetic radiation that does not carry
photon energy to ionize atoms or molecules.

+ Non-ionizing radiation consists of electric &
magnetic fields, UV rays, infrared, Laser rays,
Microwave, Ultrasound waves.

11. NON-IONIZING RADIATION

ULTRA- RADIO WAVES
INFRARED
VIOLET RADAR TV FM
| I

I I
400 nm 700nm1000nm 0.01 cm 1 cm

12. MECHANISM OF ACTION

There are two theories exist to
understand the mechanism of action.

+ Target theory
« Indirect action theory

13. TARGET THEORY

¢ This theory proposes that radiant energy acts

by direct hits on target molecules within the
cells e.g. DNA. This can lead to Mutation,
Genetic or Cancerous predisposition,
Inhibition of cell division, Cell death, Damage
to cell membrane or enzymes.

14. TARGET THEORY

e Radiant energy, charged
particles cause injury with

this method.

15. INDIRECT ACTION THEORY

e This theory proposes that the radiant energy
exerts its effect by producing free radicals within

the cells e.g. H”, OH-, H202, HO2. There free
radicals may interact with them and can cause
damage to cell membrane, nucleic acids,
enzymes and even may cause cell death.

16. INDIRECT ACTION THEORY

e Radiant energy, gamma
and X-rays act by this

mechanism.

17. BIOLOGICAL EFFECTS OF
RADIATION

18. « The harmful effects caused to human beings
and other living beings due to their exposure
to radiation is called as biological effects of
radiation.

« High radiation doses tend to kill cells, while
low doses tend to damage or alter the
genetic code (DNA) of irradiated cells.

19. BIOLOGICAL EFFECTS OF
RADIATION ON LIVING CELLS
MAY RESULT IN THREE
OUTCOMES:

20. 1.Injured or damaged cells repair themselves,
resulting in no residual damage.

2.Cells die, much like millions of body cells do
every day, being replaced through normal
biological processes; or

3.Cells incorrectly repair themselves resulting
in a biophysical change.

21. SOME TISSUES
AND TUMORS

Sy, _ ARE MORE
"| SENSITIVE TO

sa (1? RADIATION
>) IN THAN OTHER.

22. e Sensitive tissues: - Lymphoid, hemopoietic,
spermatogonia, ovarian follicle.

+ Sensitive tumors: - Leukemia, lymphoma,
seminoma, dysgerminoma.

+ Resistant tissues: - Bones, cartilage, muscles,
peripheral nerves.

+ Resistant tumors: - gliomas, sarcomas,
melanoma, osteosarcoma.

23. EFFECTS OF RADIATION ON
CELLS
(IONIZING RADIATION)

24. + Biological effect begins with the ionization of
atoms. The mechanism by which radiation
causes damage to human tissue, or any other
material, is by ionization of atoms in the
material. lonizing radiation absorbed by
human tissue has enough energy to remove
electrons from the atoms that make up
molecules of the tissue.

25. The following are possible effects of radiation on
cells:

e Cells are undamaged by the dose: - lonization
may form chemically active substances which
in some cases alter the structure of the cells.
These alterations may be the same as those
changes that occur naturally in the cell and
may have no negative effect.

26. e Cells are damaged, repair the damage and
operate normally: - Some ionizing events
produce substances not normally found in the
cell. These can lead to a breakdown of the cell
structure and its components. Cells can repair
the damage if it is limited. Even damage to the
chromosomes is usually repaired. After this cell
operate normally.

27. e Cells are damaged, repair the damage and operate
abnormally : - lf a damaged cell needs to perform a
function before it has had time to repair itself, it will
either be unable to perform the repair function or
perform the function incorrectly or incompletely. The
result may be cells that cannot perform their normal
functions or that now are damaging to other cells. These
altered cells may be unable to reproduce themselves or
may reproduce at an uncontrolled rate. Such cells can be
the underlying causes of cancers.

28. e Cells die as a result of the damage: - Ifa
cell is extensively damaged by
radiation, or damaged in such a way
that reproduction is affected, the cell
may die. Radiation damage to cells may
depend on how sensitive the cells are to
radiation.

29. e Selective inhibition of cell proliferation is
the most important effect.

e Damage of cytoplasmic enzymes,
macromolecules and organelles.

+ Damage to DNA may lead to: Oncogenic
transformation Heritable genetic defect
to children.

30. EFFECTS ON ORGANS AND
SYSTEMS OF BODY

31. DOSE OF RADIATION:

Acute radiation dose:

—
- An acute radiation dose is defined as
a large dose (10 rad or greater, to the
whole body) delivered during a short
period of time (on the order of a few
days at the most). If large enough, it
may result in effects which are

observable within a period of hours to
weeks.

32. DOSE OF RADIATION:

—
- Acute doses can cause a
pattern of clearly identifiable
symptoms (syndromes). These
conditions are referred as
Acute Radiation Syndrome.

33. « Blood-forming organ (Bone marrow)
syndrome :- (>100 rad) is characterized
by damage to cells that divide at the
most rapid pace (such as bone marrow,
the spleen and lymphatic tissue).
Symptoms include internal bleeding,
fatigue, bacterial infections, and fever.

34. ¢ Gastrointestinal tract syndrome:-(>1000 rad)
is characterized by damage to cells that
divide less rapidly (such as the linings of the
stomach and intestines). Symptoms include
nausea, vomiting, diarrhea, dehydration,
electrolytic imbalance, loss of digestion
ability, bleeding ulcers, and the symptoms
of blood-forming organ syndrome.

35. e CNS Syndrome :-(>5000 rad) is
characterized by damage to cells that do
not reproduce such as nerve cells.
Symptoms include loss of coordination,
confusion, coma, convulsions, shock, and
the symptoms of the blood forming organ
and gastrointestinal tract syndromes.

36. OTHER
EFFECTS
FROM AN

"N ACUTE DOSE
INCLUDE

37. 1. 200 to 300 rad to the skin can result in the
reddening of the skin (erythema), similar to a
mild sunburn and may result in hair loss due

to damage to hair follicles.

2. 125 to 200 rad to the ovaries can result in
prolonged or permanent suppression of
menstruation in about fifty percent (50%) of
women.

38. 3. 600 rad to the ovaries or
testicles can result in permanent
sterilization.

4. 50 rad to the thyroid gland
can result in benign (non-
cancerous) tumors.

39. CHRONIC RADIATION DOSE

A chronic dose is a relatively small amount of
radiation received over a long period of time. The
body is better equipped to tolerate a chronic
dose than an acute dose. The body has time to
repair damage because a smaller percentage of
the cells need repair at any given time. The body
also has time to replace dead or non-functioning
cells with new healthy cells. This is the type of
dose received as occupational exposure.

40. SOME RADIATION
CHANGES ARE AS
FOLLOWS:

41. 1) Skin

Post irradiation erythema
(2-3 days)

Post radiation edema (2-3
weeks)
Epithelial blistering (4-6
weeks)

Chronic radiodermatitis
(Months / years)

42. 2) Skin cancers (years)

Hemopoietic and
lymphoid tissue
+ Severe lymphopenia
+ Severe neutropenia
. Bone marrow
depression

43. 3) Lungs
« Fatal respiratory
failure
+ Marked pulmonary

edema
Radiation
pneumonitis

44. 5) Brain

-It is relatively
radioresistant in adult
males. It shows focal
necrosis only with
high doses of
radiations.

45. Biological Effects of Radiation

1,

Somatic Effects Genetic Effects

>,

Early Effects Late Effects

AS

Effect on Tissue Carcinogenic Effect

|

Deterministic Dose Effect Stochastic Dose Effect

46. Dose wise effects of radiations are as follows

10-50 rads No obvious effects

50-100 rads Vomiting, Nausea, Fatigue, lymphopenia,
Neutropenia.

100-200 rads Vomiting, Nausea.

200-350 rads Severe gastrointestinal syndrome

350-550 rads GI+ Haeopoietic syndromes Death in 50%
cases

550-750 rads 100% deaths in 6 months

1000 rads Death within days

5000 rads Death within hours to days

47. EFFECTS OF NON-IONIZING
RADIATION

48. e Laser rays: It may cause
damage to lens, bone
marrow, endocrine glands
and DNA.
Microwave: thermal

injuries, painful burn,
cataracts(due to exposure
of high level of
microwaves on eye)
e Ultrasound waves: It may
alter nerve transmission.

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