The document discusses radiation used in medical imaging, its biological effects, and safety. It defines radiation and exposure, describing types used in imaging like x-rays and gamma rays. Radiation can cause acute effects like burns or long-term effects like cancer. Biological effects are categorized as somatic, affecting exposed individuals, or genetic, affecting descendants. Somatic effects include short-term deterministic effects above a threshold dose and long-term stochastic effects like cancer. Genetic effects can cause mutations passed to offspring. The document outlines protecting personnel through time, distance and shielding principles and protecting patients by avoiding repeat exposure and using shielding.

1. Presented by Akari Kyaw
Final Year
B. Med. Tech (MIT)
3.6.2020(Wed)

2. Contents
 Definition of radiation and radiation exposure
 Types of Radiation used in medical imaging
 Effects of radiation
 Biologic effects
 Categories of biologic effects
 Personnel safety
 Patient safety

3. What is radiation?
 Radiation is energy that comes from a source and travels through space and
may be able to penetrate various materials.
 the emission of energy as electromagnetic waves or as moving subatomic
particles, especially high-energy particles which cause ionization.
 For examples,
 ultraviolet light from the sun,
 heat from a stove burner,
 visible light from a candle
 x-rays from an x-ray machine
 alpha particles emitted from the radioactive decay of uranium
.

4. Radiation Exposure
 a measure of the ionization of air due to ionizing radiation from
photons; that is, gamma rays and X-rays
 defined as the electric charge free by such radiation in a
specified volume of air divided by the mass of that air.

5. Ionization
Free radicals
(chemical changes)
Molecular changes
(DNA, RNA, enzymes)
Subcellular damage
(membranes, nuclei, chromosomes)
Cellular level
Exposure
Cell death
Deterministic effects
Cellular transformation
(may be some repair)
Stochastic effects
Direct action
Fig;Change of events
following exposure to
ionization

6. Types of radiation used in medical imaging
 X-rays
 Gamma rays
 Other forms of ionizing radiations
All kinds of ionizing radiation can produce health effects.

7. Biologic Effects(cont;)
 Means as damage to living tissues of animals and humans
exposed to radiation
 can cause acute health effects such as skin burns and
acute radiation syndrome
 can also result in long-term health effects such as cancer and
cardiovascular disease.

8.  Biological effects of radiation on living cells may result
in three outcomes:
 (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 ...

9. Cell sensitivity to radiation exposure depends on four
characteristics of the cell;
 Age
 Differentiation
 Metabolic rate
 Mitotic rate
According to this, sensitive cells to radiation include;
 Blood cells 8 Blood producing cells
 Skin cells 8 mucosal lining of mouth, nose and GI
 Thyroid gland, female breast 8 tissues of younger age

10. Categories of biologic effect
 Somatic effects
 Occur in the individual exposed
 Short term somatic effects
 Long term somatic effects
 Genetics effects
 Occur in the descendants of those individuals as a result of lesions in the
germinal cells

11. Somatic effects
 When living organisms experience biologic damage from
exposure to radiation, the results of this exposure are classified as
somatic effects.
 Depending on the length of time from the moment of irradiation to
the first appearance of symptoms of radiation damage, the effects
are classified as either;
Short term somatic effects
Long term somatic effects

12. Short term somatic effects(Cont;)
 Predictable
 Are termed deterministic effects or non stochastic effects
 Characterized as having a threshold dose below which the
effects will not occur
 Value of threshold dose may vary from individual to
individual
 If the threshold dose is exceeded, the effect occurring
increases rapidly.

13.  Are observed within 3 months
 Associated with relatively high radiation doses greater than 50
rad
 Can be observed and studied in radiation therapy patients and in
the victims of radiation accidents and atomic bomb blasts.

14. Possible high dose consequences include;
 Nausea
 Vomiting
 Erythema
 Epilation
 Blood disorders
 Intestinal disorders
 Fever
 Dry and moist desquamation
 Depressed sperm count in the male
 Temporary or permanent sterility in the male and female
 Injury to the central nervous system

17. These short term somatic effects are called ACUTE
RADIATION SYNDROME.
 Acute radiation syndrome contains;
 Hematopoietic syndrome(1 to 10 Gy)
 Gastrointestinal syndrome(6 to 10 Gy)
 Cerebrovascular syndrome(50 Gy and above)

18. Long term somatic effects ( Cont;)
 Consequences of radiation exposure that appear months or years
after exposure
 These effects may result from the following;
 Previous whole or partial body acute exposure
 Previous high radiation doses
 Long term, low level doses sustained over several years

19. Long term somatic effects include;
 Long term deterministic somatic effects
 Teratogenic effects
 Long term stochastic effects

20.  Long term deterministic somatic effects
Cataract formation
Fibrosis
Organ atrophy
Loss of parenchymal cell
Reduced fertility
Sterility

21.  Teratogenic effects
 Embryonic, fetal, or neonatal death
 Congenital malformations
 Decreased birth weight
 Disturbances in growth and or development
 Increased stillbirths
 Infant mortality
 Childhood malignancy
 Childhood mortality

22.  Long term stochastic effects
Cancer
Hereditary effects
Major types of long term effects
Carcinogenesis
Cataractogenesis
Life span shortening

23. Genetic effects
 Biologic effects of ionizing radiation on future generations
 Changes or mutation to the genes may be caused when
ovaries or testes are exposed to ionizing radiation
 Faulty genetic information is transmitted to the offspring
 May manifest as various diseases or malformations

24. Spontaneous mutations in human genetic material cause a wide
variety of disorders or diseases, including;
 Hemophilia
 Huntington’s chorea
 Down syndrome
 Duchenne’s muscular dystrophy
 Sickle cell anemia
 Cystic fibrosis
 hydrocephalus

25. Huntington’s
chorea
Duchenne’s muscular
dystrophy

26. Sickle cell anemia
Cystic fibrosis

30.  Personnel safety
The three principle methods must be used;
 Time
 Shorten the time of exposure
 Distance
 Increasing the distance from radiation source
 Shielding
 Types of shielding include lead aprons, gloves, goggles and thyroid shields

31. Patient protection
 Avoid errors
 Avoid repeat exposure
 Collimate
 Use the highest kVp that is consistent with acceptable image
quality
 Use at least 40 inches SID
 Fast IRs
 Provide shielding

34. References
 Radiation Protection in Medical Radiography
By Mary Alice Statkiewicz Sherer, Paula J. Visconti, PhD, DABR, E.
Russell Ritenour, Kelli Haynes, MSRS, RT(R)