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

Types of Radiation Electromagnetic Corpuscular Acoustic Gravitational

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.

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

Spontaneous radioactive decay X rays λ<10-9m Solar/Manmade Penetrating ability: Air- 120-240m Tissue- 15-30cm Lead- 0.3mm γ rays λ<10-11m Spontaneous radioactive decay Air-400m Tissue- 50cm Lead- 40mm

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- 0.005-0.3mm Tissue- 0.06-4.0mm Air- 6-300cm Penetrating ability: Sometime used in radiotherapy to treat superficial tumors

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

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

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

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

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

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

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

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

PRINCIPLES OF RADIATION PROTECTION

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