Hazards Of Radiation Of Oral Cavity

Hazards Of Radiation Of Oral Cavity

Describe in detail about hazards of radiation of oral cavity and add a note on radiation protection.
Answer.

Hazards of Radiation of oral cavity

Oral Mucosa

• Oral mucous membrane contains the basal layer of differentiating inter mitotic cells which are highly radiosensitive at the end of second week of therapy the mucous membrane begins to show areas of redness and inflammation, this state is called as “Mucositis.”
• As the therapy continues the mucous membrane breaks down with the formation of white or yellow pseudomembrane.
• At the end of therapy, the mucositis is severe, painful leading to difficulty in talking, eating and swallowing.
• After termination of therapy, the healing may be complete after about two months, but the mucous membrane tends to become thin, atrophic and relatively avascular. Secondary infection by Candida albicans is very common complication.
• Patient is usually prone to oral ulcerations and unable to tolerate dentures.

Hazards of Radiation of oral cavity Effects on Taste Buds

• Taste buds are sensitive to radiation even therapeutic dose of radiation causes degeneration of taste buds.
• Loss of taste sensation occurs during 2nd and 3rd week of therapy.
• Loss of taste sensation can be partial or complete.
• Posterior two-third of the tongue when irradiated effects the bitter and acid flavors.
• Anterior one-third of the tongue when irradiated effects sweet and salty flavors.

Hazards of Radiation of oral cavity Effects on salivary Glands

• Parenchymal component of the gland is sensitive to radiation.
• Glands demonstrate progressive fibrosis, adiposis, loss of fine vasculature.
• There is marked decrease in salivary flow.
• The composition of saliva is affected.
• There is increased concentration of sodium, chloride, calcium, magnesium ions and proteins.
• Saliva losses its lubricating properties.
• Mouth becomes dry and tender due to xerostomia.
• pH of saliva is decreased which may initiate decalcification of enamel.

Hazards of Radiation of oral cavity Effects on teeth

Adult teeth are resistant to the effects of radiation.

Hazards of Radiation of oral cavity Radiation Caries

• Involve mainly cementum and dentin at cervical lesion.
• Dark pigmentation of crown.
• Superficial lesion affects buccal, incisal, palatal and occlusal surfaces.

During Development

• Before calcification: There is complete destruction of tooth bud which results in partial anodontia.
• Once calcification starts: Hypoplastic changes seen.
• During root development: Retardation or loss of root development.

After Eruption

Radiation caries: It is a form of rampant caries; it is secondary to the change in saliva.

Effects on Bone

• Marrow is replaced by bone marrow and fibrous connective tissue.
• Endosteum becomes atrophic.
• Bone becomes hypovascular hypocellular and hypomineralized.
• The complication following irradiation, i.e. “osteoradionecrosis”.
• Necrosis of bone may result in nonhealing ulcer which may occur after tooth extraction.
• Lack of osteoblastic and osteoclastic activity in endosteum.
• Mandible affects more than maxilla.

Radiation Protection

Radiation protection is divided into three parts, i.e.

• Protection of patient from radiation
• Protection of operator from radiation
• Protection of other persons from radiation

Protection of Patient

• X-ray machine: Good machines of reputed companies should be used.
• Selection of film: F- and E-speed films are used as they are of good quality and are highly sensitive. E speed films or Ekta speed films reduce exposure to 40%.
• Focal spot film distance: Longer is the focal spot film distance decrease is in the exposed tissue volume.
• Source skin distance: Increase in the source skin distance reduces the size of beam and reduces the volume of tissue irradiation which decreases the patient dose.
• Filtration: Low energy X-ray beam is removed by the filtration. As these X-rays do not contribute to the image formation they should be removed before they reach to the patient as they lead to the radiation exposure.
• X-ray collimation: It prevent the scattering. Beam should be collimated so that it is not more than 7 cm in diameter at the face of patient. Rectangular collimators should be preferred as they reduce the amount of tissue radiation.
• Intensifying screen: Use of rare earth screen decreases dosage for extraoral films.
• Grid: Grid decreases the fogginess of film due to the secondary radiation, this reduces the need for repeating the film.
• Kilovoltage: Operation of X-ray unit should be done at 60 to 90 kVp. X-ray beam of low kilovoltage leads to the higher patient doses, mainly to skin.
• Position-indicating devices: A 12 to 16 inches long position indicating device reduces exposure to patient as compared to short position indicating device. Open ended, circular or rectangular lead-lined cylinders are preferred to direct the X-ray beam.
• Lead aprons should be used who have lead content equivalent to 0.25 mm aluminum which is to be worn by patient during taking the radiograph.
• Thyroid collars should be weared to protect thyroid gland from radiation.
• Film-holding devices: They stabilize the X-ray film in mouth and so the hands of patient are not exposed to radiation.
• RVG: It decreases the dose of radiation required in IOPA..

Protection of the operator

Operator should not hold X-ray film in mouth of patient at the time of exposure.

Operator should not stabilize the X-ray machine at the time of exposure.

Operator should not stand in the path of primary radiation.

Operator should have to stand behind a lead barrier which consists of 0.5 mm lead equivalent during the exposure.

Operator should stand 6 feet away from primary X-ray beam.

Operator should have radiation exposure monitored by personal monitoring devices or film badges.

• Operator should work on the rotation of duties, to avoid accidental exposure.
• The maximum permissible dose for whole body exposure per year for occupationally exposed individual is 5 rem. It should be noted that operator should not go above the range of maximum permissible dose.

Protection of other Persons

• Persons who are needed should stay in the room.
• Conch shell design of operatory area is recommended for protection of people in the surrounding areas.
• X-ray tube is away from doorways to avoid the accidental exposure.
• Monitoring of the radiation exposure to room and adjacent office premises is done.
• Walls of X-ray shooting room consists of either the barium plaster or the increased thick walls which consists of additional layer of bricks.
• Displaying of warning signs and caution should be done.
• Regular radiation surveys should be carried out at regular intervals to detect the amount of radiation exposure