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RL 2 CHapter 4. oral radiology lecture pptx
- 1. 1 ADDIS ABABA UNIVERSITY SCHOOL OF MEDICINE DENTAL DEPARTMENT DANGERS/HAZARDS OF X-RAYS Dr. Lakew
- 2. Contents 1. Temporary (repairable) 2. Permanent (non repairable) 2.1. Somatic effect(Immediate,Late) 2.2. Genetic effect 3. Radiation units & dose
- 3. X-rays cannot be seen, heard or felt. They cannot be perceived by any of the senses It is easily forgotten that they are potentially dangerous to health; and just as easy to ignore every safety precaution. An overdose can give rise to serious effects, ranging from a mild burn to leukemia.
- 4. Dr. Lakew Permanent (non repairable) 1. Somatic Effect 1.1. Immediate Effects The hands are the first areas to show signs of the illness (ill- effects) of over exposure, such as dryness, thickening, desquamation cracking. 4
- 5. Dr. Lakew 1.2. Later effect Lower dosages over a long period of time have a cumulative effect Irritation to the eyes. Damage the blood forming organs , specially to bone marrow. - anemia - Leukemia - neoplastic 5
- 6. 2. Genetic Effect • Changes chromosomes whenever male or female gonads are irradiated • Can cause mutations which are usually harmful and may be associated with - abortion, - still birth - physical or mental handicap in the offspring. 6 Dr. Lakew
- 7. RADIATION UNITS 1-Roentgen (R) Unit of X-ray exposure 2-Rad Unit of absorbed dose 3-Rem Unit of biological damaging effect
- 8. RADIATION UNITS Traditional units S I UNITS Conversions Exposure Roentgen Coulomb/kg (c/kg) 1C/ kg=3876R ABSORBED DOSE Rad Gray(Gy) 1Gy=100Rad Biological effect Rem Sievert(Sv) 1sv=100Rem RADIOACTIV ITY Curie(Ci) Bequerel(Bq) 1bq=2,7x10- 11 Ci
- 9. The unit of absorbed dose in radiation dosimetery has been for many years is RAD Old units S. I . units 1. 5 rems per year 0.05 SV per year 2. 3 rems per quarter 0.03 SV per quarter 3. 1 rem total to a fetus in case of pregnant women's 0.01 SV to fetus pregnant women's
- 10. The average dosage received by any individual over 10years is 4 rad The permitted dose per week is 100 mrems or 1 msievet , no larger than 200mrems ( 0.2 MSV) per week Less than 50 films /week should wear monitoring badges periodIcally at 6 monthly intervals Greater than 50 films /week should wear monitoring badges continuously
- 11. 1 Rem = 1 Rad In dental radiography. The rem is a relatively large unit and a more practical unit is usually employed called a milli rem ( mrem) 1mrem =1/1000rem The grey( GY) is the new unit of absorbed dose ,it is hundred times lager than the rad and this unit is calledv Seivert ( SV) 1 SV = ! Grey in dental radiography
- 12. Assignment 2 1. Unit of radiation 2. The average dosage received by any individual 3. The permitted dose per week
- 13. 13