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SHIELDING AND RADIATION PROTECTION IN DIAGNOSTIC RADIAOGRAPHY According to CHOP Radiation Safety Manual, techniques of external radiation protection include the following four measures:1. Maximizing the distance from source.2. Minimizing the radiation exposure time.3. Proper shielding of the radiation source.4. Shielding the patients and personnel.Shielding of PatientsShielding must be carried out strictly in the following manner; Gonads of the patient should be shielded with at least 0.25 mm lead equivalence during diagnostic radiographic exposures.
According to American Academy of Pediatrics only those areas which are to be examined must be exposed to X-rays, to accomplish this automatic collimators are used on the X-ray equipment.In case of the patient being an infant, various immobilization devices should be used to immobilize the infant and obtain the best picture with first exposure to avoid further exposures (1973). Shielding of PersonnelAccording to CHOP Radiation Safety Manual , all persons (personnel or attendants of the patient) must compulsorily wear leaded aprons during an exposure.
The personnel should wear leaded glasses and thyroid shield to reduce the exposure of eye lenses and thyroid gland to scattered radiation. Any person with his/her hand near primary beam must wear leaded gloves to minimize the exposure.Structural ShieldingThe radiographic room should be properly shielded in the walls to avoid radiation effect outside the room and the walls should not be tampered. According to Seeram (2001) the current radiation protection standards include:I. Radiation Protection Principles andII.
Radiation Protection Actions.While the radiation protection principles include the following three concepts:a. Justification: this concept focuses on the net benefit that the patient gets due to the exposure.b. Optimization: this concept state that "all exposures be kept as low as reasonable achievable (ALARA)."c. Dose Limitation: harmful effects due to over exposure can be prevented or minimized by calculating the dosage limits. "The annual whole body occupational dose limit is 50 milliSieverts (mSv).
" The radiation protection actions comprise of:i. Time: Since the dose is directionally proportional to the exposure time, thus the time of exposure needs to be reduced.ii. Shielding: to reduce the dose, a suitable shield needs to be placed between the patient and the source. Gonadial shielding is the best example.iii. Distance: The dose received by an individual is inversely proportional to the square of the distance.I = 1/d2 Where I is the intensity of radiation and d is the distance from source.
"As the distance is increased, the dose is reduced proportionally to the square of the distance."In concluding remarks I would like to state that shielding is not the only measure to protect an individual (patient or personnel) from exposure to irradiation, other factors as mentioned in the book by Euclid Seeram (2001) are also important and need to be borne in mind by the radiologist and the personnel. BibliographyCHOP Radiation Safety Manual. Diagnostic Energized Equipment University of Pennsylvania.
Radiation Safety Office. Available on [March 21, 2006]Radiation Protection in Diagnostic Radiography of Children. American Academy of Pediatrics. Committee on Radiology. Pediatrics Vol.51, No.1, January 1973.Euclid Seeram. Rad Tech's Guide to Radiographic Protection (2001). Blackwell Publishing. ISBN 0865425809
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