This document discusses radiation protection, including natural and manmade sources of radiation, units of measurement for radiation exposure and dose, the different types of ionizing radiation and their effects on cells. It describes determinisitic and stochastic health effects and emphasizes the importance of optimizing radiation protection to keep doses as low as reasonably achievable. Key aspects of a radiation protection program include establishing barriers against radiation, monitoring radiation exposure with personnel dosimeters, and regulatory bodies that set radiation safety standards.

1. RADIATION PROTECTION

2. 2

5. Natural and Manmade sources

6. Radiation protection, also known as radiological
protection, is defined by the International Atomic Energy
Agency (IAEA) as
• "The protection of people from harmful effects of
exposure to ionizing radiation, and the means for
achieving this".
• Exposure can be from a source of radiation external to
the human body or due to internal irradiation caused by
the ingestion of radioactive contamination.

7. X-ray tube
Primary beam
Scattered radiation
Patient

8. Protection
• Why?
• From What?
• Whom to protect?
• How to protect?

9. MEASUREMENTS!!!

10. RADIATION UNITS
• ROENTGEN– unit of
radiation exposure that
will liberate a charge of
2.58x10-4coulombs/kg
of air.
• Independent of the
area or field size

11. Absorbed dose
• Deposition of energy in pt by radiation exposure
• Independent of composition of irradiated
material and energy of beam
• RAD: unit of absorbed dose
• GRAY: SI unit of absorbed dose
• Gray defined as the quantity of radiation that
results in an energy deposition of 1 joule per
kilogram.
• I GRAY = 100 RAD
• 1RAD = 1 cGY

12. Dose equivalent
• It is a measure of biological effectiveness of radiation
• REM: unit of absorbed dose equivalent
• SIEVERT : SI unit
• 1 sievert = 100 rems
• Dose equivalent=Absorbed dose x QF.
• REM = RADS X QUALITY FACTOR

13. Quality factor
• It is the parameter used to describe the quality of beam.
• Gives the amount of energy deposited per unit length travel.
Expressed in KeV per micron.
Type of radiation Q factor
X rays 1
Gamma rays 1
Beta particle 1
Electrons 1
Thermal neutrons 5
Other neutrons 20
Protons 20
Alpha particle 20

14. EFFECTIVE DOSE EQUIVALENT
• Purpose – to relate exposure to risk
• It is calculated by multiplying the dose equivalent
received by each individual organ or tissue (DT) by an
appropriate tissue weighting factor (WT) and
summing for all the tissues involved.

17. SOURCES OF RADIATION
• Natural radiation:
1. External: Cosmic and gamma radiation
2. Internal: radionuclides with in the body
ingested or inhaled
• Medical procedures:
1. Diagnostic
2. Therapeutic
• Nuclear weapons/industry/accidents

18. Electromagnetic Waves
Low HighENERGY
Radio
waves
Microwaves
Radar
Infrared
Visible
light
Ultra-violet
X-ray
Gamma-ray
Non-ionizing radiation
Ionizing radiation

19. Primary Types of Ionizing Radiation
• Alpha particles
• Beta particles
• Gamma rays (or
photons)
• X-Rays (or photons)
• Neutrons
Ionizing Radiation
alpha particle
beta particle
Radioactive Atom
X-ray
gamma ray

20. Direct Ionization Caused By:
• Protons
• Alpha Particles
• Beta Particles
• Positron Particles

21. Indirect Ionization Caused By:
• Neutrons
• Gamma Rays
• X-Rays

23. Radiation health effects
CELL DEATH BOTH
TYPE
OF
EFFECTS
CELL TRANSFORMATION

24. Radiation health effects
DETERMINISTIC
Somatic
Clinically attributable
in the exposed
individual
CELL DEATH
STOCHASTIC
somatic & hereditary
epidemiologically
attributable in large
populations
ANTENATAL
somatic and
hereditary expressed
in the foetus, in the live
born or descendants
BOTH
TYPE
OF
EFFECTS
CELL TRANSFORMATION

25. • Deterministic
(Threshold/non-stochastic)
• Existence of a dose threshold
value (below this dose, the effect
is not observable)
• Severity of the effect increases
with dose
• A large number of cells are
involved
Radiation injury from an industrial source
Deterministic effects

26. • Permanent sterility
• males
• females
3.5-6 Gy
2.5-6 Gy
• Temporary sterility
• males
• females
0.15 Gy
0.6 Gy
Threshold Doses for Deterministic Effects
• Cataracts of the lens of the eye 2-10 Gy

27. Stochastic Effects
• Stochastic(Non-Threshold)
– No threshold
– Probability of the effect increases with dose
– Generally occurs with a single cell
– e.g. Cancer, genetic effects

28. CHAIN OF EVENTS FOLLOWING EXPOSURE TO IONIZING
RADIATION
CELL DEATH
DETERMINISTIC EFFECTS
CELLULAR TRANSFORMATION
MAY BE SOME REPAIR
STOCHASTIC EFFECTS
exposure
ionisation
free radicals
(chemical changes)
molecular changes
(DNA,RNA, ENZYMES)
SUBCELLULAR DAMAGE
(MEMBRANES, NUCLEI, CHROMOSOMES)
CELLULAR LEVEL

30. Radiosensitivity [RS]
• RS = Probability of a cell,
tissue or organ of suffering an
effect per unit of dose.

31. RS laws (Law of Bergonie & Tribondeau)
Radiosensitivity of living tissues varies with maturation &
metabolism;
1. Stem cells are radiosensitive. More mature cells are more resistant
2. Younger tissues are more radiosensitive
3. Tissues with high metabolic activity are highly radiosensitive
4. High proliferation and growth rate, high radiosensitivty

33. Optimization of protection
Protection should be optimized in relation to
The magnitude of doses,
Number of people exposed
For all social and economic strata of patients.

34. All doses should be kept
• As
• Low
• As
• Reasonably
• Achievable

37. Types Of Barriers
Protection is required against
three types of radiation: the
primary radiation; the scattered
radiation; and the leakage
radiation through the source
housing.
A barrier sufficient to attenuate
the useful beam to the required
degree is called the primary
barrier.
The required barrier against stray
radiation (leakage and scatter) is
called the secondary barrier.

40. Primary Barriers
40

41. 41

42. SHEILDING
42
TECHNOLOGIST . 25 mm LEAD
• LEAD APRON, GLOVES
• THYROID SHIELD, GLASSES
PATIENT –
GONAD SHEILDING . 5 mm LEAD

43. GONAD SHIELDING
• MUST BE . 5 MM OF LEAD
• MUST BE USED WHEN GONADS WILL LIE WITHIN 5
CM OF THE COLLIMATED AREA
• Male vs. female shielding

49. The Regulatory Bodies

50. • There are various Regulatory Bodies at the
international and National level, which lay down
norms for radiation protection.
• These are
• the International Commission for Radiation
Protection ( ICRP),
• the National Commission for Radiation Protection
(NCRP ) in America,
• and the Atomic Energy Regulatory Board (AERB) in
India.

51. • The International Commission of Radiation
Protection (ICRP) was formed in 1928 on the
recommendation of the first International Congress
of Radiology in 1925.
• The commission consists of 12 members and a
chairman and a secretary who are chosen from
across the world based on their expertise.
• The first International Congress also initiated the
birth of the ICRU or the International Commission
on Radiation Units and measurements

52. • The Indian regulatory board is the AERB, Atomic
Energy Regulatory Board.
The Atomic Energy Regulatory Board was
constituted on November 15, 1983.
President of India.
Section 27 of the Atomic Energy Act,
1962.

53. • Radiation safety in handling of radiation generating
equipment is governed by section 17 of the Atomic
Energy Act, 1962, and the Radiation Protection
Rules (RPR)
• The “Radiation Surveillance Procedures of Medical
Applications of Radiation,” specify general
requirements for ensuring radiation protection in
installation and handling of X-ray equipment.
Guidance and practical aspects on implementing
the requirements of this Code are provided in
revised documents issued by AERB in the year 2001

54. Radiation protection
survey and programme

55. • The responsibility for establishing a radiation
protection programme rests with the hospital
administration / owners of the X-ray facility
• The administration is expected to appoint a
Radiation Safety Committee (RSC), and a Radiation
Safety Officer (RSO).
• Recommended by NCRP that the RSC should
comprise of a radiologist, a medical physicist,, a
senior nurse and an internist.

56. This survey has 5 phases which are
Investigation:
Inspection:
Measurement:
Evaluation:
Recommendations:

57. Depicts the organizational flow chart and the administrative
and functional components of radiation protection program.

58. Personnel Dosimeters
• Desirable characteristics
– Should be lightweight, durable, and reliable
– Should be inexpensive
• Types of personnel dosimeters
– Film badge
– Pocket ionization chambers
– Thermo luminescent dosimeters (TLD)