1. RADIATION: TYPES, UNITS & PROTECTION.
SUFYAN IBRAHIM
4th SEM
KASTURBA MEDICAL COLLEGE, MANIPAL.

2. Types of Radiation
Electromagnetic
Corpuscular
Acoustic
Gravitational

3. Ionizing Radiation
Electromagnetic: X rays, γ rays.
Corpuscular: α particles, β particles, etc.
Cosmic rays.
Non-ionizing Radiation
UV rays.
Visible light.
IR rays.
Microwaves.
Radio waves.

4. Ionizing Radiations
Ability to penetrate tissues.
Carry KE>10eV .
Deposit its energy within them.
Ionize atoms, molecules
Break chemical bonds,
Very harmful.

5. Spontaneous radioactive decay
X rays
λ<10-9m
Solar/Manmade
Penetrating ability:
Air m
Tissue cm
Lead- 0.3mm
γ rays
λ<10-11m
Spontaneous radioactive decay
Air-400m
Tissue- 50cm
Lead- 40mm

6. 10x powerful than X, β, γ rays but least penetrating power.
2He4 nucleus.
10x powerful than X, β, γ rays but least penetrating power.
Lead- 0
Tissue- 0.05mm
Air- 4cm
Penetrating ability:
Very dangerous if entered into the body(by inhalation or wounds)
β rays
Electrons or Positrons.
More penetrating than α but less than γ rays.
Lead mm
Tissue mm
Air cm
Penetrating ability:
Sometime used in radiotherapy to treat superficial tumors

7. NON-IONIZING RADIATIONS Order of Decreasing Energies
EM radiations of longer wavelengths but KE<10eV thus non-ionizing
Sufficient energy to change the rotational, vibrational or electronic valence configurations of molecules/atoms UV
Visible Light IR
Microwaves
Radio waves
Order of Decreasing Energies
Greater the wavelength, lesser the energy(E α 1/λ)
Thermal ionization is still possible at far higher energies

8. Sunlight, electric arcs, Hg-vapour lamps 10nm<λ<400nm
UV Rays
Sunlight, electric arcs, Hg-vapour lamps
10nm<λ<400nm
Uses: Endogenous Vit D production, Serotonin productiion
Bad effects: Suntan, Freckling, Sunburn, Skin cancer

9. R A D I T O N U S Radio-activity
Becquerel, Curie, Rutherford, Mache-Einheit
Potency of Radiation
Roentgen, Rad, Rem
SI units
C/kg, Gray, Sievert

10. UNITS FOR ACTIVITY(A)
The activity of a radioactive material is the number of nuclear disintegration per unit time
SI Unit(derived) is becquerel(Bq)
One becquerel is defined as the activity of a quantity of radioactive material in which one nucleus decays per second
1Bq=27pCi [1Ci=3.7×1010 Bq]
1Rd=2.703 × 10−5Ci [1 million nuclei decay/sec]
1ME=3.64×10−10 Ci/L

11. UNITS FOR EXPOSURE(X)
Roentgen(R) is the measure of the ionization produced in air by X-rays or γ rays and it is used because air ionization can be measured directly
“Amount of radiation absorbed in air at a given point, i.e., number of ions produced in 1mL of air”
SI Unit is Coulomb per kilogram(C/kg)
1R=2.58×10−4 C/kg

12. UNITS FOR ABSORBED DOSE(D)
Rad: Amount of radioactive energy absorbed per gram of tissue or any material
SI Unit is Gray(Gy): Dose of ionizing radiation that impart 1 joule of energy to 1 kg of absorbing material
1rad=0.01Gy

13. UNITS FOR DOSE EQUIVALENT(H)
Represent the stochastic biological effects of ionizing radiations per unit of energy absorbed
Indicates degree of potential danger for health
H is the product of absorbed dose(D) and quality factor(Q)
Q depends upon density of ionization produced in tissue by the radiation(for X,γ,e-=1, for particle=20)
So, H=D*Q
Units: Rem(Roentgen equivalent in man) and Sievert(Sv)
1Sv=100rems

14. Radiation Protection
Radiation Hygiene
Prepare Safety Standards
Codes for safe operation of Nuclear Power Plants
Peaceful use of Atomic Energy
ICRP, IAEA and WHO
The protection of people from harmful effects of exposure to ionizing radiation, and the means for achieving this

16. PRINCIPLES OF RADIATION PROTECTION

17. REGULATION OF DOSE UPTAKE
JUSTIFICATION
No unnecessary use of radiation is permitted; The advantages must outweigh the disadvantages.
LIMITATION
Each individual must be protected against risks that are far too large through individual radiation dose limits.
OPTIMIZATION
Radiation doses should all be kept ALARA/ALARP