Protection From Radiation Question And Answers

Protection From Radiation

Question 1. Write short note on protection from X-ray.
or
Describe briefly radiation protection of patient.
or
Discuss radiation protection of patient in detail.
Answer. The radiation protection of patient is describe as:

Read And Learn More: Oral Radiology Question And Answers

• 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.

Question 2. discuss radiation protection method in detail.
or
Discuss in detail about radiation protection in dental radiology.
or
Write a short note on radiation safety measures for operator and patients.
Answer.

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

Question 3. Enumerate only the principle of radiation protection.
or
Write short answer on ALARA principle.
Answer. Philosophy of radiation protection is based on ALARA principles.

The term ALARA ‘As low as reasonably achieved’ is more commonly used to describe radiation protection measures to be used to minimize patient and operator exposure.

• ALARA principle which recognizes the possibility that no matter howsmallthedoseissomestochasticeffectmay result.
• For dentist the ALARA principle entails the obligation to minimize the radiation dose to patient and surroundings to a level as low as reasonably achievable.
• ALARA principle should be followed:
  • Radiation workers:
    • Occupational exposure is 20 mSv/year averaged over a defined period of 5 year which is maximum of 50 mSv (5 rem) in any one year.
    • Women of reproductive age and pregnancy should not exceed—10 mSv (1 rem)
  • Members of the public
    • Annual effective dose for the public should not exceed—1mSv (0.1 rem)
    • In any one year members of public should not receive an effective dose equivalent in cases of—5mSv (0.5 rem)

Question 4. What are the radiation hazards? describe how these are avoided and how radiation doses are measured?
Answer. Following are the hazards of radiation:

Radiation Hazard on skin

The reaction of the skin to radiation may be categorized as:

• Early or acute signs:
  • Increased susceptibility to chapping.
  • Intolerance to surgical scrub.
  • Blunting and leveling of finger ridges.
  • Brittleness and ridging of finger nails.
• Late or chronic signs:
• Loosening of hair and epilation.
• Dryness and atrophy of skin, due to destruction of the sweat glands.
• Progressive pigmentation, telangiectasis and keratosis.
• Indolent type of ulcerations.
• Possibility of malignant changes in tissue.

Radiation Hazard on Eyes

• Epilation of eyelashes.
• Inflammation, fibrosis and decreased flexibility of the eyelid.
• Damage to the lacrimal glands, leading to dryness.
• Ulceration of the cornea.
• Initiation of cataract formation from the periphery towards the center.

Radiation Hazard on Ears

• Columnar epithelium of the middle ear may be desquamated.
• Edema of the mucosa and collection of sterile fluid in the middle ear, which leads to obstruction of the eustachian tube known as radiation otitis media.
• Deafness due to rupture of eardrums.

Radiation hazard on Reproductive system

• On Testicles:
  • Suppression of germinal activity.
  • Alteration in fertility.
  • Functional changes in the offspring may be seen.
• On Ovary:
  • The various cells respond differently to irradiation.
  • Increase in frequency of hemangioma in children receiving dose of radiation in utero.

Radiation hazard in 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.

Radiation Hazard 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.

Radiation Hazard 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.

Radiation Hazard Effects on Teeth

Adult teeth are resistant to the effects of radiation.

Radiation Hazard Radiation Caries

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

Radiation Hazard 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.

Radiation Hazard After Eruption

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

Radiation Hazard Effects on Bone

• Marrow is replaced by bone marrow and fibrous connective tissue.
• Endosteum becomes atrophic.
• Bone becomes hypovasular 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 Hazard Acute Radiation syndrome

When the whole body is exposed to low or moderate doses of radiation, a very characteristic change are seen known as acute radiation syndrome. This can be followed by death within a month. If an individual survive, it can show late somatic changes which are:

• Prodromal syndrome (1 to 2 Gy): Shortly after exposure patient may develop nausea, vomiting, diarrhea and anorexia.
• Latent period: It is a period of apparent well being, the extent of which is dose related. Symptoms follow the latent period when the individuals are exposed in the lethal range (approximately 2–5 Gy) or the supralethal range (more than 5 Gy).
• Bone marrow (hemopoietic) syndrome {2 to 7 Gy): Here severe damage may be caused to the circulatory system. The bone marrow being radiosensitive, results in fall in the number of granulocytes, platelets and erythrocytes. Clinically, this is manifested as lymphopenia, granulocytopenia and or hemorrhage due to thrombocytopenia and anemia due to depletion of the erythrocytes.
• Gastrointestinal syndrome (7 to 15 Gy): This causes extensive damage to the gastrointestinal tract, leading to anorexia, nausea, vomiting, severe diarrhea and malaise. Injury to the basal cell epithelial cells of the intestines causes denuded mucosal surfaces, leading to loss of plasma and electrolytes, hemorrhage and ulcerations leading to diarrhea, dehydration and loss of weight. Finally, leading to septicemia unusually leading to death.
• Cardiovascular and central nervous system syndrome (more than 50 Gy): This produces death within one or two days. Individuals show intermittent stupor, incoordination, disorientation and convulsions suggestive of extensive damage to the nervous system.

Protection from Hazards of 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

Measurement of Radiation dose

Radiation dose is measured by the dosimetry. Dosimetry is the determination of the quantity of radiation exposure or dose.

Following are the various measures of dosimetry:

• Dose: It is the amount of radiation at the given point or the amount of energy absorbed per unit mass at the site of interest.
• Erythema dose (3 to 4 Gy): It is the dose which produces in one sitting a reversible reddening of skin.
• Exposure: It is a measure of radiation quantity, the capacity of the radiation to ionize the air. SI unit of exposure in air is Kerma.
• Absorbed dose: It is the measure of the energy absorbed by any type of ionizing radiation per unit mass of any type of matter.
• Equivalent dose (HT): It is used to compare the biologic effects of different types of radiation to a tissue or organ. It is the sum of absorbed dose averaged over a tissue or organ and radiation weighing factor.
• Effective dose (E): It is used to estimate the risk in humans. It is the sum of the products of the equivalent dose to each organ or tissue and the tissue weighing factor. Its unit is Sievert (Sv).
• Radioactivity: It describes the decay rate of a sample of radioactive material. Its SI unit is Curie (Ci).
• Maximum permissible dose: It is a equivalent which a person or specified parts of person shall be allowed to receive in a certain stated period of time.
• Maximum accumulated dose: This dose indicates the higher limits permitted for occupationally exposed persons do not pertain to individuals under the age of 18 and dental assistants under the age of 18 are limited to the same exposure as general public, i.e. 0.0005 Sv/year.

Question 5. Write short note on units of measurement of radiation.
Answer. Units for measuring qualities in radiation dosimetry are:

Conversion

1 Gy = 100 Rad

1 Sv = 100 Rem

1 Bq = 2.7 × 10-11 Ci

1 Ci = 3.7 × 1010 Bq

Roentgen (R)

Amount of radiation which produces 2.08 ×109 ion pair in ICC of air.

• If was used to measure intensity of radiation.
• It is the unit of exposure.
• This was not acceptable for biological tissue since roentgen was measured in air.
• Kermar eplace the roentgen at the unit of radiation exposure.

Kerma (Kinetic Energy Released in Matter)

• SI unit of exposure in air
• It measures the kinetic energy transferred from photon to electron.

Rad (r) Radiation absorbed dose

• It is the unit of absorbed radiation (traditional unit).
• It is the production of 100 ergs of radiation in 1 gm of tissue by any form of ionizing radiation.
• It is replaced by a new unit gray.
  • 1 Gy = 1 joule/Kg = 100 r.

Radiaton Equivalent Mammal (REM)

It is the unit of dose equivalent. This unit is used to facilitate comparison between biological effects of exposure and various types of radiation.

1 Sv = 100 rem.

In Diagnostic Radiology

1 R = 1 r = 1 rem

Question 6. Write short note on position and distance rule.
Answer.

• This rule implies on the protection of the operator.
• This rule is for the protection against primary beam.
• The rule states that the operator should stand at least 6 feet away from the source of radiation at an angle of 90 to 135° with respect to direction of central rays.
• This rule takes advantage of inverse square law to reduce the intensity and also considers that in this position patient’s head will absorb most scattered radiation.

Question 7. Write short note on TLD badges.
or
Write short note on TLD
Answer. The full form of TLD badge is Thermoluminescence Dosimeter badge.

• TLD badge is used for measurement of actual dose received by operator or patient due to radiography or radiotherapy exposure and are personal monitoring devices.
• It is easily placed over the body since its size is very small.

Thermoluminescence Dosimeter badge Structure 

• TLD badge in India consists of TLD card holder cassette which is made up of high impact plastic, TLD card has nickel plated aluminum plate consisting of three symmetrical holes in which calcium sulphate embedded Teflon disks are inserted.
• These teflon disks are clipped on aluminum card which is loaded in cassette and consists of three filters, i.e. open region, copper and aluminum.

Thermoluminescence Dosimeter badge Principle

• When phosphorous is irradiated the X-ray energy is absorbed and secondary electrons are emitted.
• Secondary electrons create holes in filled zone by lifting electrons to conduction band.
• Here the electrons fall back in traps in metastable state where they held up.
• When phosphorus is heated at 2000 to 3000°C the trapped electrons acquire energy to escape back to conduction band.
• From conduction band, the electrons fall back to fill holes in filled zone when they recombine visible light is produced known as thermoluminescence.

Thermoluminescence Dosimeter badge Reader

• Equipment which heat the exposed material and measure emitted light is known as TLD reader.
• Reading produced by TLD reader is used as a measure of absorbed dose to which material is subjected.
• It consists of three parts, i.e. heater, photomultiplier tube and electronic system.

Wearing of TLD Badge

• Chest badge consists of metallic clip which is to be worn outside the clothes. It should be kept below lead apron.
• Wrist badges consist of snap for attachment.

Thermoluminescence Dosimeter badge Indications

• In radiotherapy
• In radiodiagnosis
• For personal monitoring

Thermoluminescence Dosimeter badge Advantages

• It is chemically inert.
• Size is small and light in weight.
• Reusable
• Provide accurate readings
• It is economical
• Can be used for various range of radiation qualities.

Thermoluminescence Dosimeter badge Disadvantages

• Provide limited information.
• Dose gradients are not detected.
• Records are not permanent.

Question 8. What is aLaRa principle. discuss the radiation protection for dental patient.
Answer. ALARA means “as low as reasonably achievable” ALARAprinciple recognizes the possibility that no matter how small the dosage is some stochastic effect may occur.

ALARA Principle is as Follows:

• In radiation workers:
  • Occupationally exposed person—50 mSv or 5 rem in any one year.
  • Women of reproductive age and pregnancy should not exceed 10 mSv or 1 rem.
• Members of the public:
  • Annual effective dose for public should not exceed 1 mSv or 0.1 rem.
  • In any one year members of public should not receive an effective dose equivalent in cases of 5 mSv or 0.5 rem.

Radiation Protection of dental 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.

Question 9. Write short note on dosimetry.
Answer. Radiation dose is measured by the dosimetry.

• Dosimetry is the determination of the quantity of radiation exposure or dose.
• Radiation dosimetry deals with the measurement of the absorbed dose or dose rate resulting from the interaction of ionizing radiation with matter and particularly in different tissues of body.
• Following are the various measures of dosimetry:
• Dose: It is the amount of radiation at the given point or the amount of energy absorbed per unit mass at the site of interest.
• Erythema dose (3 to 4 Gy): It is the dose which produces in one sitting a reversible reddening of skin.
• Exposure: It is a measure of radiation quantity, the capacity of the radiation to ionize the air. SI unit of exposure in air is Kerma.
• Absorbed dose: It is the measure of the energy absorbed by any type of ionizing radiation per unit mass of any type of matter.
• Equivalent dose (HT): It is used to compare the biologic effects of different types of radiation to a tissue or organ. It is the sum of absorbed dose averaged over a tissue or organ and radiation weighing factor.
• Effective dose (E): It is used to estimate the risk in humans. It is the sum of the products of the equivalent dose to each organ or tissue and the tissue weighing factor. Its unit is Sievert (Sv).
• Radioactivity: It describes the decay rate of a sample of radioactive material. Its SI unit is Curie (Ci).
• Maximum permissible dose: It is a equivalent which a person or specified parts of person shall be allowed to receive in a certain stated period of time.
• Maximum accumulated dose: This dose indicates the higher limits permitted for occupationally exposed persons do not pertain to individuals under the age of 18 and dental assistants under the age of 18 are limited to the same exposure as general public, i.e. 0.0005 Sv/year.