![]() ![]() It is mandatory that console have a set reminder with audible alarm, which warns when a significant radiation dose (at 5 min cumulative time), beyond which local harmful effects such as radiation burns may arise. The use of high frequency generators, which generate high KV beam will decrease the mAs required to produce diagnostically adequate X-rays thus reducing radiation dose. Tube current or mA determines the quantity of the photons and KV determines the energy of photons collectively both contributes to patient dose. Optimum technique including use in high KV and low mAs mode, beam collimation, beam filtration anti scatter grids, high speed films and processing are necessary. Time - Time is related to exposure time and exposure rate. Best time to image females child bearing age is in the 10 day period following the onset of menstruation. Placement of shield should be based on the direction of the tube during the procedure.ġ9. Protect of patients thyroid, breast and gonads in children and young adults.ġ8. Neck receives 10–20 times more radiation than the trunk which is protected by lead.ġ7. If only one dosimeter is worn it must be worn at the collar outside the lead apron.ġ6. Thyroid shields with defects greater than 11 mm 2 should be replaced.ġ5. Lead aprons defect is greater than 15 mm 2 in areas close to critical organs areas. Thyroid shield can decrease the amount of effective dose by 2.5 fold and almost 50% reduction in total exposure.ġ4. Lead apron must cover the front of the body from the throat to within 10 cm of the knees, as well as the sides of the body from the shoulder to below the buttocks.ġ3. Standard lead apron must provide at least 0.5 mm of lead or equivalent barriers.ġ2. Lead apron are secondary barriers to protect from secondary or scatter radiation.ġ1. Minimum source-to-skin distance for a stationary fluoroscopy tube should not be less than 38 cm (15 inches), and for a mobile C-arm not less than 30 cm (12 inches).ġ0. A safe distance of 2 m from the source of radiation hence exposure cord of at least 2 m length or remote control switch should be used.ĩ. When the distance is doubled the exposure is reduced by a factor of four.Ĩ. Distance – Radiation exposure inversely to proportionate to the square of the distance. Increasing accuracy of radiographs by laser targeting device s and correct positioning.ħ. Mandatory to have a set reminder with audible alarm on console which warns when a significant radiation dose.Ħ. Tube current or mA determines the quantity of the photons and KV which determines the energy of photons collectively contribute patient dose.ĥ. Optimum technique use in high KV and low mAs mode, beam collimation, beam filtration anti scatter grids, high speed films processing are necessary.Ĥ. Radiation exposure dependent on triad of "Time-Distance-Shielding".ģ. Risk of the Occupational exposure are mainly from scatter radiation exiting the patient.Ģ. It has the same units of measure as the equivalent dose.ġ. Each organ contributes with a tissue-weighting factor. Effective Dose is a measurement of the whole body dose based on the total equivalent dose received by all organs. (Old unit: rem (roentgen equivalent man). The radiation-weighting factor for X-ray in standard unit is expressed as Sievert (Sv). It is dependent on the type of radiation absorbed in a particular time duration. Equivalent Dose is a measurement of the biological effects of the radiation on a specific tissue or organ exposed to specific type of radiation. SI unit for equivalent and effective dose is Sivert (Sv). The quantity of radiation energy absorbed in a unit of mass of material is measured in international standard unit (SI unit) as Gray (Gy) and 1 Gy is equivalent to 100 rad. The energy of X-rays are greater than 5 keV and ranges from 40 to 100 keV. Gamma rays are emitted from the nucleus of a radioactive atom while X-rays are emitted when high speed electrons are slowed down or their direction is changed, in a strong electric field. Gamma-rays and X-rays, unlike alpha or beta particles are made up of individual packets of energy called photons. One eV is defined as the energy of an electron that has been accelerated through an electron potential of 1 V. The unit of energy for radiation is usually given as electron volt(s). ![]() gray per hour (Gy/h) or Sievert per hour (Sv/h). Radiation exposure dependent on time functions and is expressed as dose per unit time i.e. 9, 10 Risk of the Occupational exposure to Orthopaedic surgeons and health care personnel are mainly from scatter radiation exiting from the patient and not from the primary beam itself. The remaining exposure comes primarily from diagnostic radiography. ![]() Natural radiation sources, including cosmic rays and terrestrial radon gas, account for approximately 85% of the exposure to humans. ![]()
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