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152 Cards in this Set
- Front
- Back
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T/F: If insurance will cover fees, the patient should be scheduled for a BWX every 6 months and FMX every 3 years to ensure proper, up to date treatment
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FALSE
Radiographic exams should NEVER include a predetermined number of radiographs taken at predetermined time intervals |
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Evaluating criteria for prescribing dental radiographs and checking for proper equipment are things done to protect the patient, before, during or after exposure?
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Before exposure
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What equipment should be in place before exposures are taken to ensure that the patient minimizes exposure
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Filtration
Collimation Position/Beam Indicating Device |
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How does proper filtration protect the patient from excess exposure?
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It removes longer wavelength, low-energy x-rays from the primary x-ray beam. These long wavelength beams would increase patient dose without increasing the diagnostic value of images
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What are the sources of inherent filtration?
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Glass window of the x-ray tube
Insulating Oil |
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What is inherent filtration?
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It occurs when the primary beam passes through the glass window of the x-ray tube or insulating oil.
It is equivalent to approx 0.5-1.0mm of alumninum |
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What is added filtration?
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Placement of aluminum disks in the path of the primary beam.
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What is total filtration?
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Total Filtration = Inherent Filtration + Added Filtration
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How much Total Filtration is needed when radiation is <70kVp? >70kVp?
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< 70kVp requires > 1.5 mm total filtration
> 70kVp requires >2.5 mm total filtration |
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Restriction of the size and shape of the x-ray beam to reduce patient exposure describes what?
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Collimation
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How much collimation to a patient's skin is required by law?
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7 cm or 2.75 inches in diameter
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What is a collimator?
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A lead diaphragm within the tube or at the end of the beam indicating device. It can be round or rectangular.
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T/F: The patient is exposed to more radiation when using a circular collimator.
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True. The diameter of the circular collimator must be much larger to cover the size of the film than if the collimator matched the film's shape.
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T/F: Pointed plastic BID's reduce patient exposure and are therefore a better choice for radiographic exposures
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FALSE.
Pointed plastic BID should NOT be used because it increases the scatter radiation exposure to the patient. |
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T/F: Long BID decreases exposure to a patient.
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TRUE.
Long BID produces LESS divergence of the beam and therefore LESS exposure to the patient than a short BID |
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What are ways of protecting the patient during exposure?
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Thyroid collar
Lead apron Fast film Film-holding devices kVp Constant potential x-ray machines Proper technique |
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The thyroid collar is recommended for all intraoral exposures because it reduces dose to the thyroid by ___%. What about extraoral exposures?
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Thyroid collar reduces dose to thyroid by 50% in intraoral exposures.
It is not recommended for extraoral exposures because it can obscure anatomic structures. |
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Why is a lead apron used during radiographic exposures?
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It reduces exposure to gonads and blood forming tissues to scatter radiation.
Dose to gonads is reduced by 98% From .005 to .003 Gy |
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T/F: Everywhere in the U.S. the use of a lead apron is mandated by law.
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FALSE
It is mandated by law in select states. |
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What is the MOST effective method of reducing patient exposure to radiation?
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Use of Fast Film
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Why would a dentist switch from D speed to F speed films?
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Because F speed films are faster and can decrease radiation exposure by up to 60%
F speed films are thought to slightly decrease resolution. Studies show no impaired caries diagnosis by F speed film use |
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How does a film-holding device decrease patient exposure?
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Stabilizes film position --> reduces number of retakes
More accurately aligns film with BID Avoids use of patient's fingers to hold the film in place |
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T/F: It is unacceptable to used machines that are incapable of operating above 60 kVp.
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TRUE.
Ideal kVp is 70-90 kVp. This dose is more effective and reduces dose by 23% This reduction is in the form of low energy x-rays absorbed by the patient |
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What is the difference between AC and DC? What generator type converts AC to DC?
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Constant potential x-ray machines convert AC to DC.
AC: produces heterogenous beam of many different wavelengths DC: produces homogenous beam of consistent wavelengths over the entire exposure. This reduces patient dose by 20% but is 20% more expensive |
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Reducing the number of retakes
Having a thorough understanding of the paralleling technique, bitewing technique, bisecting angle technique, and landmarks Having an organized routine These all describe what feature during exposure to decrease radiation? |
Proper Technique
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What can be done after exposure to keep patients radiation exposure to a minimum?
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Carefully handle films to avoid artifacts
Proper darkroom management: film processing, lighting, quality assurance prodedures |
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T/F: Dental treatment can be performed on pregnant patients without complications.
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FALSE
Treatment of oral and dental disease SHOULD be done because it can decrease bacteremia from infection and decrease cortisol production by the mom. Elective treatment SHOULD NOT be done during pregnancy and should be postponed because it subjects the mom and fetus to unnecessary stress and bacteremia risk. |
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Which trimester of pregnancy should radiographic exposure be avoided in? Why?
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1st trimester. Because radiation in teratogenic.
However, if treatment is necessary, radiographs are REQUIRED as standard of care. |
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T/F: Radiographs should always be avoided when treating pregnant patients during their 1st trimester.
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FALSE
While it is best to avoid exposure in the 1st trimester, if you are going to perform treatment that would normally consist of radiographs for diagnosis, then it is REQUIRED that these be taken regardless of the state of pregnancy as a standard of care. |
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How much radiation are the gonads and fetus exposed to when using a lead apron? How much total exposure must be present before gross congenital anomalies occur?
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0.01 microsieverts (.00001 cGy) of radiation to the fetus when using a lead apron
No increase in gross congenital anomalies occurs as a result of exposures during pregnancy totaling less than 5-10 cGy |
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T/F: Radiographs should always be avoided when treating pregnant patients during their 1st trimester.
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FALSE
While it is best to avoid exposure in the 1st trimester, if you are going to perform treatment that would normally consist of radiographs for diagnosis, then it is REQUIRED that these be taken regardless of the state of pregnancy as a standard of care. |
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The gonadal/fetal dose of 2 dental films when a lead apron is used is ___ times less than 1 day of average exposure to natural background radiation in the U.S.
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700 times less.
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How much radiation are the gonads and fetus exposed to when using a lead apron? How much total exposure must be present before gross congenital anomalies occur?
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0.01 microsieverts (.00001 cGy) of radiation to the fetus when using a lead apron
No increase in gross congenital anomalies occurs as a result of exposures during pregnancy totaling less than 5-10 cGy |
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T/F: Although risks are negligible, radiographs should be used selectively and only whenever necessary and appropriate to aid in diagnosis and treatment
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TRUE
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The gonadal/fetal dose of 2 dental films when a lead apron is used is ___ times less than 1 day of average exposure to natural background radiation in the U.S.
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700 times less.
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Protection procedures to the operator are based on what 3 principles of radiation?
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X-rays travel in straight lines from sources
Inverse square law X-rays can be scattered in their path of travel |
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T/F: Although risks are negligible, radiographs should be used selectively and only whenever necessary and appropriate to aid in diagnosis and treatment
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TRUE
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Protection procedures to the operator are based on what 3 principles of radiation?
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X-rays travel in straight lines from sources
Inverse square law X-rays can be scattered in their path of travel |
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What are the 3 types of beams that are sources of potential exposure?
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Primary beam
Leakage radiation: radiation other than the primary beam that escapes through the x-ray tube housing Scattered radiation: usually from patient's skull |
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Position and Distance as well as shielding are methods used to ____.
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Reduce occupational exposure
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How is position and distance appropriately applied to minimize operator exposure?
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Stand at least 6 ft away from patient.
Stand in a quadrant at an angle between 90-135 degrees to the primary beam Operator should NEVER hold films during exposure (caregivers job - give them a lead apron) Operator should NEVER restrain a patient during exposure (caregivers job) Operator nor patient should ever hold tube-head or BID in position during exposure |
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How does shielding help to minimize operator exposure?
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Creates a barrier if operator must stand closer than 6 ft from patient (with leaded window)
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T/F: A wall that will be used as a shield should always be lead lined.
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FALSE
Although possible it is usually not necessary and common building materials in the wall are a sufficient shield. |
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Radiation Monitoring is useful in providing what information?
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Excessive occupational exposure: monitors amount of radiation that reaches body of dental personnel, film badge
Equipment monitoring: faulty tube-head seal, leaky radiation |
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T/F: Film badges should be worn on the arm at all times.
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FALSE and FALSE
Film badges should be worm between the neck and waist They should only be worn at work, only for a specified period of time, and not when receiving diagnostic or therapeutic radiation Reports should provided and may be required by state law. Pregnant employees should have one. |
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What does the NCRP stand for?
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National Council of Radiation Protection and Measurements
They define the maximum permissible dose and create protection guidelines for public exposure. |
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What is the maximum permissible dose to occupationally exposed persons including dental radiographers
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50 mSv/year
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What is the maximum permissible dose to nonoccupationally exposed persons (exclusive of background radiation and medical radiation)
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1 mSv/year
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What is the maximum permissible dose to pregnant occupationally exposed persons (to the embryo or fetus)
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0.5 mSv/month or 5 mSv for entire pregnancy
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What is the maximum permissible dose to an occupationally exposed minor?
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5 mSv/year
10% of the annual dose limit for an adult worker |
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What is the maximum permissible dose to patients?
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There is no MPD for patients. Dosage depends on patients needs
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What is MAD (Maximum Accumulated Dose)?
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MAD = (N-18) x 0.05 sV/year
Accumulated lifetime radiation dose that must not be exceeded by occupationally exposed workers. Based on worker's age. |
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What does ALARA stand for?
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As Low As Reasonably Achievable
All exposure to radiation must be kept to a minimum |
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What are the 2 mechanisms of injury from radiation? what do they have in common?
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Direct and Indirect
Both effects occur quickly Both effects take hours to decades to become evident Both are a result of ionization |
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x-ray photon directly hitting cell DNA is an example of what type of injury from radiation?
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Direct Effect
Energy of photon or secondary electron ionizes biologic macromolecules. One third of biologic effects Causes breakage of one or both strands of misrepair Primary cause of radiation induced cell death, genetic mutations, carcinogenesis |
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What are examples of indirect effect injury from radiation?
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x-ray photon causes radiolysis of water
Free radicals are oxidizing toxins which alter molecules Primary method of cell damage through x-radiation Aka radiolysis |
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How do we determine "if all ionizing radiations are harmful and produce biologic damage, what level of exposure is considered acceptable?"
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Dose-Response curves
Dose or amount of radiation is correlated with response or damage |
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Describe the Threshold Non-Linear Curve
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Small exposures do not produce measurable changes
A THRESHOLD must be reached before changes are observed |
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Describe the Linear Non-Threshold Curve
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Dose is proportional to the response
No matter how small the dose, there is some damage OR No threshold Minimal damage at first |
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What are Stochastic Effects?
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Direct function of dose
Probability of occurring increases with dose Severity does not depend on the magnitude of dose There is NO dose threshold (non-threshold curve) Ex: Cancer induction, genetic mutations |
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What are Non-stochastic/Deterministic Effects?
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Has a threshold (threshold curve)
Increases in severity with increasing absorbed dose Ex: hair loss, skin reddening, cataract formation, sterility |
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What is the 3 phase sequence for radiation injury?
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Latent period --> Period of Injury --> Recovery period
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The time that elapses between exposure and appearance of clinical signs describes what phase of radiation injury?
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Latent Period
May be short of long: Total dose, Dose rate |
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Cell death, changes in cell function, breaking or clumping of chromosomes, giant cell formation, cessation of mitotic activity, abnormal mitotic activity are characteristics of what phase of radiation injury?
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Period of injury
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In what phase of radiation injury do cells repair damage?
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Recovery period.
Not all injuries are permanent |
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T/F: Patients are subjected to less injury if doses are given all at once.
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FALSE.
When patients get fractioned doses over a period of time it allows for the recovery period to have time to repair cell damage in between doses before more damage is encountered. This minimizes the amount of irreparable injury |
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All of the following are factors that influence radiobiologic effect:
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Local vs Whole body exposure
Radiation Factors 1. Total dose 2. Penetrating ability of the beam 3. Acute vs Chronic exposure 4. Dose rate Host factors: 1. Species 2. Intrinsic resistance 3. Cells (mitotic activity, cell metabolism) |
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T/F Mammals, reptiles, insecsts, and bacteria are all equally sensitive to radiology
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FALSE
Mammals are more sensitive than reptiles, insects, bacteria |
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T/F: the more frequently a cell divides, the less specialized it is, and the higher it's metabolism, the more sensitive it is to radiation
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TRUE
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The Law of Bergonie and Tribondeau describes the most radiosensitive cells as ___ ___ ___
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Having a high mitotic rate
Undergoing many future mitosis Most primitive in differentiation |
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Large amounts of radiation absorbed in a short time describes what type of radiation effect? What are some examples?
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Short Term
Effects seen within minutes, days or weeks of exposure. Ex: Nausea, vomiting, diarrhea, hair loss, hemorrhage |
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Small amounts of radiation absorbed repeatedy over a long time describes what type of radiation effect? What are some examples?
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Long Term
Appear years, decades or generations later Ex: Cancer induction, birth abnormalities, genetic defects |
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What is the difference between somatic and genetic effects?
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Somatic : all those except reproductive cells.
1. seen in the person irradiated 2. NOT transmitted to future generations Ex. cancer, leukemia, cataracts Genetic effects 1. NOT seen in the person irradiated 2. Passed on to future generations |
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What type of effect would 1.8-2.0 Gy/day 5days/week for 5-7 weeks of radiation have on oral mucous membranes, taste buds and salivary glands, teeth, bones, musculature?
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Oral mucous membranes: red, inflamed and sloughing
Taste buds: loss of taste acuity (reversible) Salivary glands: loss of salivary func (dose dependent, often permanent) Teeth: permanent dentition defects in kids, teeth are resistant in adults. "radiation" caries due to salivary gland func loss, NOT damage to teeth Bone: damage to vasculature, destruction of osteoblasts and osteoclasts, osteoradionecrosis (bone infection) Muscles: inflammation and fibrosis --> can lead to contracture and trismus |
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T/F: "radiation caries" is a condition due to salivary glands
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TRUE.
Rather than causing destruction of tooth structure (which are fairly resilient in adults), radiation decreases salivary function and increases caries occurrence. |
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What are the units of radiation measurement
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Traditional
1. Roentgen (R) 2. Rad (radiation absorbed dose) 3. Rem (roentgen equivalent in man) SI system 1. Coulombs/kilogram (C/kg) 2. The gray (Gy) 3. The sievert (Sv) |
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The amount of radiation that produces a charge of 2.58 x 10-4 coulombs in a kg of air at standard temp and pressure conditions describes what unit of measurement?
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Roentgen (R)
has 2 billion ion pairs in 1 cubic cm of air |
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How is the measurement of ionization in air produced by x-rays described in SI terms?
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X unit - SI is the # of photons that will produce 1 coulomb of charge per kg of air
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How many R is 1 periapical or bitewing?
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0.3 R (300 mR)
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Which units are used to measure energy ABSORBED by tissue?
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Rad and Gray
Rad - equal to deposition of 100 ergs of energy per gram of tissue Gy - Amount of energy in J absorbed per kg of tissue |
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1 Gy = ? rad?
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1Gy = 100 rad
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1 rad = ? Gy?
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1 rad = 0.01 Gy or 1 cGy
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Which units measure the biologic effect of radiation?
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Rem and Sv
Rem - radiation equivalent in man Sv - product of the absorbed dose (rads) and a quality factor specific for the type of radiation Quality factors 1. x-rays, beta particles, gamma rays = 1 2. low energy neutrons, protons = 5 3. Alpha particles, high ernergy neutrons = 20 (20 times more penetrating than an x-ray) |
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How do you calculate dose equivalent (H)?
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H = D x QF
dose equivalent = (dose)(quality factor) x-rays: H = 20 Gy X 1 = 20 Sv alpha particle: H = 20 Gy x 20 = 400 Sv |
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T/F: exposure and dose both depend on the size of the beam and the volume of tissue irradiation
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FALSE
exposure and dose are INDEPENDENT of size of the beam and volume of tissue irradiation |
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Is 1 Sv to the right hand equivalent to 1 Sv to the breast?
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NO
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What is the effective dose equivalent used to assess?
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Assess risk of radiation to localized part of body and degree to which this would increase a person's "whole body" risk of cancer induction or genetic mutation induction.
Used when comparing two different x-ray exposures or the same exposure from two different machines |
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An FMX is how many Sv?
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26 microSv
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Most background radiation exposure comes from where?
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Natural radiation sources 82%
Radon Internal: food we eat Terrestrial: radioactive materials in earth, radon gas Cosmic: sun and stars |
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What is the average annual background radiation exposure for a person in the U.S.?
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3,000 microSv (FMX = 26 microSv)
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What are some examples of manmade radiation sources?
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Make up 3% background radiation
Consumer products (TV, watch, computer) Nuclear fuel cycle Weapons production Fall-out from atomic weapons |
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How much of a persons background radiation is medically associated?
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15%
medical and dental diagnostic nuclear medicine |
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Dental x-ray diagnosis makes up what % of the annual average effective dose of radiation?
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It is 4 microSv and .10% of annual avg effective dose
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What is the effective dose and days of natural background radiation for a single intraoral, bitewings (4 films), FMX, and panoramic?
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Single Intraoral: 1.3 microSv, 0.2 days
Bitwing: 5.2 microSv, 0.7 days FMX: 26 microSv, 3.2 days Panoramic: 7 microSv, 0.9 days |
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T/F: most biologic effects are not risks from dental radiography
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TRUE
Cataracts, osteoradionecrosis, xerostomia, epitaxis, erythema, epilation have a higher threshold Bone marrow destruction, GI necrosis, CV syncrome require whole body exposure Fetal abnormalities, genetic mutations, thyroid/breast cancer require irradiation of that body part |
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Is the eye at significant risk from dental radiographs?
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No. risk is extremely remote
Threshold for cataracts = 2000 mSv Dental exposure from scattered radiation = 0.5 mSv |
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Are the gonads at significant risk from dental radiographs?
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Negligible risk. No genetic effects
For sterility = 4,000-6,000 mSv Dental dose FMX = .005 mSv (no lead apron) and .0003 mSv (with lead apron) |
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Studies show a risk for congenital defects is negligible at 50 mSv or less. How worried should a pregnant patient be when getting x-rays taken?
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Negligible risk.
Dental dose of FMX = 0.005 mSv (no lead apron) to 0.0003 mSv (with lead apron) Way under the 50mSv for defects to occur |
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What is the main risk from dental radiation? why?
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CANCER - especially leukemia and thyroid cancer
There is no threshold dose. Even small doses may increase patient's risk of cancer. Spontaneous cancer rate in US is about 20% However, there are no cancers that are uniquely caused by x-rays. |
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What is the conversion from R --> C/kg? from C/kg --> R?
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1R = 2.58 x 10^-4 C/kg
1 C/kg = 3.88 x 10^3 R |
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What is the conversion from rem --> Sv? from Sv --> rem?
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1 rem = 0.01 Sv
1 Sv = 100 rem |
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The latent period is the time between...
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Exposure to x-radiation and clinical symptoms
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A free radical
a. Is an uncharged molecule b. Has an unpaired electron in the outer shell c. Is highly reactive and unstable d. Combines with molecules to form toxins e. All of the above |
E
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Direct radiation injury occurs when...
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x-ray photons hit critical targets within a cell
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Indirect radiation injury occurs when...
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x-ray photons are absorbed and form toxins
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What type of relationship described the relationship between the response of tissues to radiation? (graph shape)
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linear, nonthreshold
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Which contributes to radiation injury?
a. total dose b. dose rate c. cell sensitivity d. age e. all of the above |
E
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Which is correct?
a. short-term effects are seen with small amounts of radiation absorbed in a short period b. short-term effects are seen with small amounts of radiation absorbed in a long period c. long-term effects are seen with small amounts of radiation absorbed in a shot period d. long-term effects are seen with small amounts of radiation absorbed in a long period |
D
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Radiation injuries that are not seen in the person irradiated but that occur in future generations are termed...
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Genetic effects
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Which of the following is most susceptible to ionizing radiation?
a. bone tissue b. small lymphocyte c. muscle tissue d. nerve tissue e. epithelial tissue |
B
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Sensitivity of tissues to radiation is determined by
a. mitotic activity b. cell differentiation c. cell metabolism d. all of the above |
D
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Which of the following is considered radioresistant?
a. immature reproductive cells b. young bone cells c. mature bone cells d. epithelial cells |
C mature bone cells
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An organ that, if damaged, diminishes the quality of an individual's life is termed a ...
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Critical organ
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Traditional unit for measuring x-ray exposure in air is termed...
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Roentgen
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The quality factor is use to determine which radiation unit?
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The rem
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The unit for measuring the absorption of x-rays is...
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The rad and grey
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Which conversion is correct?
a. 1R=2.58x10^-4 C/kg b. 2rad=0.1 Gy c. 1rem=0.1Sv d. 1Gy=10rad e. 1Sv=10rem |
A 1R=2.58x10^-4 C/kg
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Which traditional unit does NOT have an SI equivalent?
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The roentgen
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Which of the following is used only for x-rays?
a. Sv b. Gy c. Rem d. Rad e R |
E The roentgen
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Which is correct?
a 1R=2.58x10^-4 C/kg b. 1By=100 rad c. 1Sv=100rem d. 1rem=radsxQF e. all of the above |
E all of the above
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What is the average dose of backgroup radiation received by an individual in the U.S.?
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150-300 mrads (0.0015-0.003 Gy)
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What is the greatest contribution to artificial radiation exposure?
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medical radiation
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Amount of radiation exposure varies depending on
a. film speed b. collimation c. technique d. exposure factors e. all of the above |
E
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A single intraoral radiograph results in a mean exposure of..
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250 mR
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What is the dose at which leukemia induction is most likely to occur?
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5000 mrads (0.05 Gy)
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T/F Every patient should be evaluated individually for dental radiographs
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T
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T/F The 8-in PID is more effective at reducing radiation exposure than the 16-in.
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F
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T/F Pointed cones should not be used because of increased scatter radiation
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T
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T/F The thyroid collar must be worn for all intraoral and extraoral films
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F
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T/F If necessary, the dental radiographer may hold the film in the patient's mouth
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F
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What is the use of a filter in dental x-ray tubeheads?
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A filter removes low-energy x-rays
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Which is NOT a component of inherent filtration?
a. oil b unleaded glass window c. leaded cone d. tubehead seal |
C leaded cone
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The most effective way of reducing patient exposure to radiation is...
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fast films
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The most effective PID indicating device at reducing patient exposure is...
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rectangular PIC
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What restricts the size and shape of the x-ray beam?
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collimator
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What material is used as a collimator?
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lead plate
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What is the recommended size of the beam at the patient's face?
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2.75 inches
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What term describes the dose of radiation that the body can endure with little or no chance of injury?
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Maximum permissible dose (MPD)
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What is true for film badges?
a. Film badges should be worn when the radiographer is undergoing x-ray exposure b. Film badges can be shared between employees c. Film badges should be worn at the waist level when exposing x-ray films |
C film badges should be worn at the waist level when exposing x-ray films
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Which is NOT a component of inherent filtration?
a. oil b unleaded glass window c. leaded cone d. tubehead seal |
C leaded cone
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The most effective way of reducing patient exposure to radiation is...
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fast films
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The most effective PID indicating device at reducing patient exposure is...
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rectangular PIC
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What restricts the size and shape of the x-ray beam?
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collimator
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What material is used as a collimator?
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lead plate
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What is the recommended size of the beam at the patient's face?
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2.75 inches
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What term describes the dose of radiation that the body can endure with little or no chance of injury?
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Maximum permissible dose (MPD)
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What is true for film badges?
a. Film badges should be worn when the radiographer is undergoing x-ray exposure b. Film badges can be shared between employees c. Film badges should be worn at the waist level when exposing x-ray films |
C film badges should be worn at the waist level when exposing x-ray films
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Is there a significant risk of leukemia with dental x-rays?
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Not really
Leukemis induction occurs at 5000 mrads or more Avg bone dose is 1-3 mrads per film |
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Is the thyroid irradiated by primary beam or by scatter radiation?
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scatter radiation?
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What is the dose for thyroid cancer to occur? how much irradiation from a fmx?
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100 mSv necessary for thyroid cancer
dose of fmx = 0.3 mSv thyroid collar reduces the dose by 50% |
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What is the risk of cancer induction from 1 FMX
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2.5 per 1,000,000 exams
Same as living as a 60 year old man for 20 min, living in denver for 2 mo, riding a bike for 10 mi, a car for 300 mi, or a plane for 1000 mi. |
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How much radiation is given during treatment of cancer compared to an FMX
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Cancer treatment = 50-70 Gy = 70,000,000 mcSv
FMX = 26 mcSv |
