Chapter 4

 All ionizing radiation is harmful and produces biologic changes in living tissues.  Although the amount of x-radiation used in dental radiology is small, biologic changes do occur.  The entire x-ray area is considered a radiation hazard area, and must be posted

 In dental radiography, not all x-rays pass through the patient and reach the dental film; the patient’s tissues absorb some x-rays. When the energy from the x-ray photon is absorbed, chemical changes result in biologic damage.

 Results in harmful effects of x-rays on humans.  Cause disruption of cellular metabolism  Permanent damage to living cells and tissues

 Exposure to radiation can bring about changes in body chemicals, cells, tissues, and organs.  Effects may not become evident for many years after the time the x-rays were absorbed.  Time lag is called LATENT PERIOD.  Think sunburn

 The additive effect of repeated radiation exposure.  Exposure to radiation has a cumulative effect over a lifetime.  Some damage will be repaired, tissues do not return to original state.  Compare to repeated exposure to sun over the years.

 Acute  Large dose of radiation is absorbed in a short period.  Ex. Nuclear accident  Chronic  Small amounts of radiation are absorbed repeatedly over a long period.  Ex. Taking dental x-rays while you are in the room.

 Genetic  Reproductive cells  Damage is passed on to succeeding generations  Genetic mutations  Somatic  All other cells in the body belong to this group  Damage is not passed on to future generations

 Skin  Thyroid Gland  Lens of the eye  Bone Marrow  Other areas of concern  Reproductive areas

MEASURED IN A MANNER SIMILAR TO TIME, DISTANCE, AND WEIGHT.  Traditional  Roentgen (R)  Radiation absorbed dose (rad)  Roentgen equivalent in human (rem)  Systeme International (metric equivalent) (SI)  Coulombs per kilogram (C/kg)  Gray (Gy)  Sievert (Sv)

 Defined as the maximum dose equivalent that a body is permitted to receive in a specified period of time. (MPD)  Dose of radiation that the body can endure with little or no injury.  Dental Personnel – 5.0rems/year= 0.05 Sv/year  Non-Occupationally exposed persons- 0.1 rems/year=0.001 Sv/year Dental Personnel should not exceed the Maximum accumulated lifetime dose, calculated as follows (N-18)x5rems/year or (N-18)x0.05 Sv/year N= operators age

 As Low As Reasonably Achievable

 When using the As Low As Reasonably Achievable (ALARA) principle, possible methods for reducing radiation exposure include using well training and competent operators, using F- speed film and  A. placing heavy cotton aprons on all patients  B. using D-speed film  C. placing lead aprons on all patients  D. using C-speed film

 Avoid exposure to reproductive organs during x- rays by using a  A. fast film  B. lead apron  C. periapical film  D. film badge