Ppt 1

• PET (positron emission tomography) uses nuclear medicine to measure physiological function by looking at blood flow, metabolism, neurotransmitters, and radiolabelled drugs

  
• The radiation weighting factor is used to calculate the effective dose of radiation, which is a measure of the potential harm caused by radiation exposure

  
• Tissue weighting factors are used to calculate the absorbed dose of radiation to a tissue or organ, representing the relative sensitivity of a tissue or organ to radiation

  
• Ionizing radiation can be classified into:

  • Particulate/Corpuscular Radiation: gamma and beta types associated with radioactive decay, directly ionizing than electromagnetic radiation
  • Electromagnetic Radiation: with electric and magnetic properties, behaving as waves and particles depending on energy and environment
• Gamma rays, with an energy range of 0.1 to 5 MeV, are emitted by nuclei of a radioactive substance and used in both diagnosis and treatment purposes
• Gamma knife surgery directs radiation to kill cancer cells by aiming multiple concentrated beams of gamma rays from different angles to minimize damage to surrounding tissue
• 1. rays, with an energy range of 10 to 150 KeV, are used in general radiography, CT scans, and mammography, originating from a filament and having the potential to damage tissue atoms by ionization
• Ultraviolet rays, with an energy range of 100 to 400 nm, are naturally produced by the sun and light bulbs, used for sterilization, viricide, bactericide, and skin condition treatments like psoriasis and vitiligo
• Infrared radiation, with an energy range of 0.7-10 mm, is used for burglar systems, remote controls, and thermography to detect pathological tissue growths
• Microwaves, with an energy range of 0.1-10 cm, are used for cooking, speed traffic detectors, and cellular telephone communication
• Radiowaves, with a frequency of 1-100 MHz, transmit radios and TV signals
• Exposure is the total electrical charge per unit mass generated by X-ray and gamma-ray photons, measured in Roentgen or c/kg
• Air kerma is the amount of energy per unit mass absorbed by the irradiated object, measured in J/kg or Gy, with radiation energy absorbed per unit mass
• Absorbed dose is the amount of radiant energy transferred to an irradiated object by any type of ionizing radiation, measured in RAD or Gray
• Equivalent dose provides a measure for the overall risk of exposure to human from ionizing radiation, incorporating both the type of radiation used and the variability in radiosensitivity of the specific organ
• Tissue weighting factor is a conceptual measure for the relative risk associated with irradiation of different body tissues to account for the carcinogenic sensitivity of each organ
• Radioactivity is the quantity of a radioactive material, measured in Ci or Bq