Tishk International UniversityFaculty of ScienceMedical Analysis Department

Personal carrier and Lab security

Grade 2- Spring Semester 2020-2021Lec: 8

Biological Effects of Radiation

Instructor: Dr Ramiar Kamal

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Aim:

• To show the biological effects ofradiation

1902: A.Frieben: Demonstration lines of the upper side of the hand, that developed after long-

term exposure to diagnostic X-rays.

16th century: unusual high incidence of fatal lung diseases among silver and tin miners in the

Erz Mountains of Saxonia (report of the local physician G.Agricola)

was termed: Schneeberger Lung Disease

1937: lung cancer in miners was associated with Radon exposure of lung epithelium

(B. Rajewski)

since 1947:

Radiation Effects Research Foundation (RERF) monitoring cancer incidenc

in A-bomb survivors of Hiroshima and Nagasaki

(RERF Foundation, Preston and Pierce, Radiation Research 160, 2003)

History of Radiation

The carcinogenic potential of ionizing radiation was recognized soon

after Roentgen's discovery of X-rays in December, 1895

Source of radiation

-Natural Radiation

There are more than 60 different

naturally occurring radioactive

materials present in the

environment, with radon gas being

the highest contributor to people’s

exposure.

-Artificial radiation.

(e.g. diagnostic radiology,

image-guided

interventions, nuclear

medicine and

radiotherapy)

Why it is important to study Radiation

According to WHO report, yearly:Radiation causes to skin melanoma over 60 000 Death by lung cancer , 88000Thyroid 20 000.

• All the cells in the body can be classified as either

somatic or genetic.

• Somatic cells are all the cells in the body except the

reproductive cells.

• The reproductive cells (e.g., ova, sperm) are

termed genetic cells.

• Depending on the type of cell injured by radiation,

the biologic effects of radiation can be classified as

somatic or genetic.

Radiation damage can be divided in to two types :

Somatic damage and genetic damage

somatic effects• Somatic effects are seen in the person who has

been irradiated. Radiation injuries that produce

changes in somatic cells produce poor health

in the irradiated individual.

• Major somatic effects of radiation exposure

include the induction of cancer, leukemia, and

cataracts.

• These changes, however, are not transmitted to

future generations

Radiation Causes Ionizations of:

ATOMS

which may affect MOLECULES

which may affect

CELLS

which may affect TISSUES

which may affect

ORGANS

which may affect

THE WHOLE BODY

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Theories of RadiationInjury

Chromatid type

Aberration

S-Phase Mitosis

Loss of

acentric fragments

If an essential gene

is lost, cell dies.

If no essential gene is lost,

cell might survive

(but might have lost

Tumor-Suppressor-Genes)

Trans-

location

If a stable translocation

is generated, cell survives

(but might acquire an

activated Oncogens )

Radiation-induced changes at Chromosomes

Chromosome type

Aberration

Deletion

Deletion

The time scales for the short and long term effects of radiation are symbolized in the figure and listed in the

table

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Double strand break is responsible

for:

-mutation

-cell death

-carcinogenisis

Point mutations:

Effect of radiation on individualgenes is referred to as pointmutation.

CHROMOSOMScell cycle:

ChromosomeAberrationsIf radiation exposure occurs after DNA

synthesis (I,e G2 or late s) only one arm of the

effected chromosome is broken

If radiation occurs before DNA synthesis (G1 or

early S) both arms are effected

EXAMPLES OFMUTATIONS

The mechanisms of IR-induced inflammation and diabetes

Cardiovascular diseases related to ionizing radiation

Overview of the major steps in the pathogenesis of coronary artery disease at the local and systemic level. Flashes

indicate events that were also observed after radiation exposure, and which are mainly related to inflammation. ECs, endothelial cells; LDL, low-density lipoprotein; IL-6, interleukin-6; CRP, C-reactive protein.

The mechanisms of IR-induced inflammation or anti-inflammatory responses

Ionizing radiation has been suggested asplaying a role in plasma membranedamage, which may be an important factorin cell death (interphase death)

Radiation Induced Membrane damage

Effect of radiation on body(1) Hair

The losing of hair quickly and in clumps occurs with radiationexposure at 200 rems or higher.

(2) Brain

Since brain cells do not reproduce, they won't be damageddirectly unless the exposure is 5,000 rems or greater. cancause seizures and immediate death.

(3) Thyroid

The thyroid gland is susceptible to radioactive iodine. In sufficientamounts, radioactive iodine can destroy all or part of thethyroid.

(4) Reproductive Tract

Because reproductive tract cells divide rapidly, these areas of thebody can be damaged at rem levels as low as 200. Long-term, some radiation sickness victims will become sterile.28

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(5) Blood System

When a person is exposed to around 100 rems, the blood's

lymphocyte cell count will be reduced, victim more

susceptible to infection.

According to data from Hiroshima and

Nagaski, show that

symptoms may persist for up to 10 years and may also have an

increased long-term risk for leukemia and lymphoma.

(6) Heart

Intense exposure to radioactive material at 1,000 to 5,000 rems

would do immediate damage to small blood vessels and

probably cause heart failure and death directly.

(7) Gastrointestinal Tract

Radiation damage to the intestinal tract lining will cause

nausea, bloody vomiting and diarrhea. This is occurs when

the victim's exposure is 200 rems or more.

8- Skin

9-Eye

10-Bone marrow26

ORAL MUCOUS

MEBRANE

TASTE BUDS

SALIVARYGLANDSSalivary gland:

Increase the growth of st.mutans,lactobacillous,candida

Decrease the ph leads to decalcification of enamel

Difficult to swallow (DISPHAGIA)

Decrease salivary secretion (XEROSTOMIA)

.The gland demonstrates progressive fibrosis adiposis, loss of

fine vasculature and simultaneous parenchymal

degeneration.

Acute Radiation Effects:Localized Exposure

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Acute Radiation Effects:

Localized Exposure

Protection from External Radioactivity

➢Time – minimize time exposed

➢Distance – Increase distance from source

➢Shielding – Increase shielding

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Internal Average dose for year x hours worked

+

External Annual total of radiation badge (TLD)

+

Radioactive gas Annual radon and thoron gas exposure

= Total radiation exposure

Calculating the radiation dose

Thank you

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