Term
|
Definition
| the study of the effects of ionizing radiation on living tissue, to understand the harmful effects of radiation. |
|
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Term
|
Definition
| there are two mechanisms of radiation injury; ionization and free radical formation |
|
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Term
|
Definition
| the unit of measurement describing the potential that drives an electrical current through a circuit. |
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Term
|
Definition
| equal to 1,000 volts. dental machines require high voltage between 65-100kv. |
|
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Term
|
Definition
| there is a device in each dental x-ray machine that insures the voltage never goes above a certain reading (although it may fall below it). That specific highest reading is the kilovolt peak. |
|
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Term
|
Definition
| the mean energy, or penetrating ability of the x-ray beam |
|
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Term
|
Definition
| refers to how dark or black the image is. |
|
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Term
|
Definition
| how sharply dark or light areas are differentiated on an image. Low contrast has more shades of gray. High contrast is more black and white. |
|
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Term
|
Definition
the length of time x-rays leave the machine is measured in impulses per second. 60 impulses occur each second. * this is the only exposure factor that can be altered on most machines |
|
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Term
|
Definition
A unit of electrical current strength, the intensity of an electrical current produced by one volt acting through a resistance of 1 ohm.
Determines the amount of electrons passing through the filament. The more electrons created, the more waves possible. |
|
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Term
|
Definition
| 1/1000 of an ampere. Dental x-ray units operate between 7-15 Ma. |
|
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Term
| milliampere-seconds (mAs) |
|
Definition
milliamperes X exposure time (in seconds)
This is an adjustable setting on some machine that could be used for things such as needing to expose a film faster. When you raise the mAs you must LOWER the exposure time. |
|
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Term
|
Definition
| Controls the penetrating power of the x-ray beam by controlling the # of electrons produced in the tube and the # of x-rays produced. |
|
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Term
|
Definition
| refers to the # of x-ray waves produced. the higher the mAs the more waves produced. |
|
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Term
| the effects of mAs on density of an image |
|
Definition
| the higher the Ma setting the more dense the image |
|
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Term
|
Definition
| equal to the quantity (# of photons) X quality (energy of photons)/ area X exposure rate |
|
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Term
|
Definition
| the higher the kvp the higher the intensity (higher kvp increases energy of photons) |
|
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Term
|
Definition
| the higher the Ma the higher the intensity (higher Ma=more electrons) |
|
|
Term
| intensity and exposure time |
|
Definition
| the longer the exposure time the higher the intensity. (exposure time controls how many waves are emitted) |
|
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Term
|
Definition
| higher distance= less intensity |
|
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Term
|
Definition
| the distance form the source of radiation to the patients skin |
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Term
|
Definition
| the distance from the source of the radiation to the tooth |
|
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Term
|
Definition
| the distance from the source of radiation to the film |
|
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Term
|
Definition
| intensity is inversely proportional to the square of the distance from the source. move the source 2X further away, the intensity is only 1/4 of what it was before. |
|
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Term
|
Definition
| when an object such as aluminum disks are placed in the path of a x-ray beam, the thickness of that material that is capable of reducing the intensity of the beam by half is referred to as the half value layer. |
|
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Term
|
Definition
| when kvp is increased by 15, exposure time must be decreased by half. When kvp is decreased by 15, exposure time must double. |
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Term
| what are the 4 main components of film? |
|
Definition
1)film base
2)adhesive layer
3)film emulsion
4)protective layer |
|
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Term
|
Definition
| Transparent, flexible polyester plastic, .2mm thick. It can withstand heat, moisture, and chemical exposure. Slight blue hint to emphasize contrast and inhance image. Provides a stable support for the emulsion. Provides strength. |
|
|
Term
| describe the adhesive layer |
|
Definition
| a thin layer of adhesive on both sides of the film base for the emulsion to attach to |
|
|
Term
| describe the film emulsion |
|
Definition
| a homogeneous mix of gelatin and silver halide crystals. Gives the film greater sensitivity to radiation. Covers both sides of the film. |
|
|
Term
| describe the gelatin of film emulsion |
|
Definition
| it suspends and evenly disperses the silver halide crystals. During processing it absorbs the solutions and allows the chemicals to react with the silver halide crystals. |
|
|
Term
| Describe the silver halide crystals of the film emulsion |
|
Definition
| A halide is sensitive to light. Crystals made of a silver plus a halogen: bromine or iodide. Both are found in the film emulsion which is typically 80-99% silver bromide and 1-10% silver iodide. The silver halide crystals absorb radiation and store engery. |
|
|
Term
| describe the protective layer on film |
|
Definition
| It is a thin, transparent layer over the emulsion. Protects the film from manipulation, mechanical and processing damage. |
|
|
Term
| What is a latent image and how is it formed? |
|
Definition
| A latent image is the image on a film that is not yet visible because it hasn't been processed. It is formed when photons strike the film, causing the silver halide crystals to be engergized and seperate the silver from the halide. |
|
|
Term
| What are the 4 component of an intra oral film packet? |
|
Definition
1)the xray film
2)paper film wrapper
3)lead foil sheet
4)outer package wrapping |
|
|
Term
| what is the purpose of the paper film wrapper in a film packet? |
|
Definition
| It wraps the film to shield it from light |
|
|
Term
| What is the purpose of the lead foil sheet inside the intral oral film packet? |
|
Definition
| The lead foil sheet goes behind the xray film to shield it from backscatter (secondary) radiation, which would cause fog. |
|
|
Term
| Describe the outer package wrapping of an intra oral film |
|
Definition
| It's made of either soft vinyl, or paper. It is water and light tight. It has 2 distinct sides, the tube side and the label side. |
|
|
Term
| Which side of the intral oral film package should face towards the teeth and the tube head when being exposed? |
|
Definition
| The tubehead side, which is solid white and has a raised bump. |
|
|
Term
| Name the 3 types of intra oral film |
|
Definition
1) periapical
2) bite-wing
3) occlusal |
|
|
Term
|
Definition
| an intra oral film that is used to take an image of the entire tooth including the crown, root and surrounding bone. |
|
|
Term
|
Definition
| an intra oral film that either has wing like tabs on it, or attaches to a holder. Used for taking images of the mandibular and maxillary teeth at the same time. It is useful for showing the interproximal spaces of teeth. |
|
|
Term
|
Definition
| an intraoral film that is used for imaging large areas of the jaw. The patient bites on the entire film. |
|
|
Term
| what sizes does periapical film come in? |
|
Definition
size 1- for small children
size 2- for adult anteriors
size 3- for adult anterior and posterior |
|
|
Term
| What sizes does bite wing films come in? |
|
Definition
size 0- for posterior teeth in small children
size 1- children's posterior, or vertically placed for adult posteriors
size 2- adult posterior, most frequently used
size 3- longer and narrower than size 2, used to image all the posteriers of a one arch |
|
|
Term
| what size does occlusal film come it? |
|
Definition
|
|
Term
| what does film speed refer to and what speeds are available? |
|
Definition
| Film speed refers to how sensitive the film is. A-E is available (D discontinued) with A being the slowest and E being the fastest. |
|
|
Term
| What is the most commonly used film speed in dentistry? |
|
Definition
| E, it only needs 60% of the radiation that D needs. |
|
|
Term
| What is film speed determined by? |
|
Definition
1)crystal size
2)thickness of emulsion
3)presence of radioactive dies |
|
|
Term
|
Definition
| Extra oral film does not need to be moisture proof since it does not go in the mouth. The film is classified as either screen or non screen. |
|
|
Term
| What is the difference between screen and non screen film? |
|
Definition
| Screen film is sensitive to fluorescent light and requires an intensifying screen to expose an image. The intensifying screen converts xrays into light to expose the film. This process uses less radiation than traditional non screen film, so it is what is used in dentistry. |
|
|
Term
| describe duplicating film |
|
Definition
used only in a dark room
not exposed to x-rays
only has emulsion on one side
emulsion side appears dull, film side appears shiny
emulsion side must contact radiograph during duplication |
|
|
Term
| How should film be stored? |
|
Definition
In a cool dark place (such as a frig)
at temps between 50-70 F and humidity between 30-50%. Should not be stored in a room that is used to expose radiographs. If possible stored in a lead line, or radiation resistant box. |
|
|
Term
|
Definition
the portion of the image on developed film that appears dark/black.
The structures that appear dark/black lack the density to absorb the x-ray beams, therefore the allow the passage of x-ray beams to strike the film. |
|
|
Term
| What are the 3 exposure factors that influence density? |
|
Definition
- mA- increasing the mA increases the density due to more x-rays produced.
- kv- increasing the kvs increases the density as higher energy x-rays are produced
- exposure time- increasing the exposure time increases the density as the total number of x-rays that reaches the film is increased
|
|
|
Term
|
Definition
the part of the image on exposed film that appears white or light.
The structures depicted were dense enough to absorb the x-ray beams and therefor did NOT allow the passage of x-ray beams onto the film. |
|
|
Term
|
Definition
| the overall darkness/blackness of an image |
|
|
Term
|
Definition
| the difference between degrees of dark and light |
|
|
Term
|
Definition
| very dark and very white image with very little difference between shades |
|
|
Term
|
Definition
| several shades of gray in between black and white |
|
|
Term
| which type of contrast is preferred in a dental radiograph, high or low contrast? |
|
Definition
| a compromise of the two is preferred |
|
|
Term
|
Definition
| characteristics of film that influence the radiographic contrast such as the inherent qualities, film processing, subject contrast and thickness. |
|
|
Term
| What are the inherent qualities of film? |
|
Definition
| These qualities are controlled by the manufacture and cannot be altered by the operator. eg expiration date |
|
|
Term
| What components of film processing can alter film contrast? |
|
Definition
| Development time and temperature affects contrast. The higher the temperature, and the longer the time in the developer, the higher the film contrast will be (less shades of gray) |
|
|
Term
| How can subject contrast alter film contrast? |
|
Definition
| The characteristics of the subject that influence film contrast are thickness, density, and composition (atomic number) |
|
|
Term
| What exposure setting can alter film contrast? |
|
Definition
| Increasing the kvp will decrease the film contrast. Higher energy x-rays will be produced that are better at penetrating the subject so more x-rays reach the film. (remember low contrast means MORE shades of gray) |
|
|
Term
| define "scales of contrast" |
|
Definition
| Useful densities are termed scales of contrast. They are either short or long. |
|
|
Term
|
Definition
high contrast- shows only 2 densities (black and white).
could be caused by low kvp
remember a black bird high in the sky on a white cloud |
|
|
Term
|
Definition
Correct contrast- exhibits many densities, many shades of gray.
Remember a long gray snake low to the ground with many shades of gray in his pattern. |
|
|
Term
|
Definition
| A step wedge is a piece of aluminum that has 2 mm "steps" cut into it. It is placed on top of a piece of film and then exposed to demonstrate the corresponding film densities and contrast scales. |
|
|
Term
| what are the 3 geometric properties that influence the diagnostic quality of film? |
|
Definition
| Sharpness, magnification, and distortion. |
|
|
Term
|
Definition
| Refers to the distinct outline of an object. Sharpness is desirable in a dental radiograph. |
|
|
Term
|
Definition
A shadow of an object. Lacks sharpness, is fuzzy.
Penumbras are present to some degree in every image. |
|
|
Term
| What 3 factors influence sharpness of an image? |
|
Definition
| focal spot size, film composition, and movement |
|
|
Term
|
Definition
The smaller the focal spot (tungsten target) the sharper the image.
Focal spot size is limited to .6-1.0 mm depending on manufacture. |
|
|
Term
| what effect does film composition have on the sharpness of the image? |
|
Definition
| The sharpness of the image is relative to the size of the crystals. Large crystals produce less sharpness because they do not outline an image as well as small crystals do. |
|
|
Term
| how does movement affect image sharpness? |
|
Definition
| If either the film or the patient moves during exposure a loss of sharpness will occur. |
|
|
Term
|
Definition
| Refers to a radiographic image that appears larger in size than the actual image. Results from divergent paths of the x-ray beam. Because of this there is some degree of magnification in every image. |
|
|
Term
| What are factors that influence image magnification? |
|
Definition
2 factors can influence image magnification - target film distance- Determined by the PID. Longer PIDs mean that more parallel beams from the middle of the tube are able to strike the film. This results in less magnification.
- object film distance- object film distance should be kept to a minimum as much as possible. The closer the film is to the object the less magnification occurs.
|
|
|
Term
|
Definition
| the variation in size AND shape of the object. Results from unequal magnification of different parts of the same image. Could be caused by improper film alignment or beam angulation. The x-ray beams must be perpendicular to the film. |
|
|
Term
| what factors can influence image distortion? |
|
Definition
1) object film alignment
2) x-ray beam angulation |
|
|
Term
| what are the two mechanisms of radiation injury? |
|
Definition
1)ionization - a)absorption/photoelectric
- b)compton
2) free radical formation - a)may combine with other free radicals and cause damage
- b)may combine with ordinary molecules (such as h20) and form toxins (such as hydrogen peroxide h2o2)
|
|
|
Term
| Describe the ionization that takes place when x-rays strike the patient's tissues |
|
Definition
| Ionization results in the formation of a positive atom and a dislodged electron. The ejected high speed electron is set into motion and interacts with other atoms within the absorbing tissues. The kinetic energy of such electrons results in further ionization, excitation, or breaking of molecular bonds all of which cause chemical changes within the cell that result in biologic damage. Ionization may have little effects on cells if the chemical changes do not alter sensitive molecules, or such changes may have a profound effect on structures of great importance to cell function (eg DNA) |
|
|
Term
|
Definition
| an uncharged (neutral) atom or molecule that exists with a single unpaired electron in it's outermost shell. It is unstable and highly reactive, always trying to stabilize by combining with other atoms or molecules. The life span of a free radical is aprox 10 to the power of -10 seconds. |
|
|
Term
| What is the direct injury theory? |
|
Definition
| suggests that cell damage results when ionizing radiation directly hits critical areas or targets of the cell. eg, the photon strikes the DNA causing critical damage. Direct injuries from ionizing radiation occur infrequently, most photons pass through the cell and cause little or no damage. |
|
|
Term
| what is the indirect injury theory? |
|
Definition
suggests that x-ray photons are absorbed within the cell and cause the formation of toxins which in turn damage the cell.
eg photons absorbed by the water in the cell forming a free radical. The free radicals combine with each other to form toxins (H2O2), which causes cellular dysfunction and biologic damage. Thus injury occurs because the free radicals combine and form toxins, NOT because of the direct hit by an x-ray. |
|
|
Term
| What is the sequence of radiation injury? |
|
Definition
The latent period- the time between the exposure and the first appearance of injury Period of injury- a variety of cellular injuries may result: cell death, changes in cell function, breaking or clumping of chromosomes, formation of giant cells, cessation of mitotic activity and abnormal mitotic activiy. Recovery period- Not all cellular injuries are permanent. Cell damage is followed by cell repair. Most low level radiation is repaired. |
|
|
Term
| what is meant by "cumulative effects" of radiation exposure? |
|
Definition
| the effects of radiation are additive and unrepaired damage accumulates in the tissue. These cumulative effects can lead to health problems (eg cancer, cataract formation, and birth defects) See table 4-1 for complete list. |
|
|
Term
| what 5 factors determine radiation injury? |
|
Definition
| total dose, dose rate, amount of tissue irradiated, cell sensitivity, and age. |
|
|
Term
|
Definition
| Quantity received, or total radiation energy absorbed. |
|
|
Term
|
Definition
Dose/time (divided by)
rate at which exposure occurs and absorption takes place.
More damage occurs with rapid delivery because this does not allow the cells time to repair in between injuries. |
|
|
Term
| amount of tissue irradiated |
|
Definition
areas of the body exposed to radiation.
Extensive radiation injury occurs when larger areas are irradiated because of the damage to blood forming tissues. |
|
|
Term
| cell sensitivity to radiation injury |
|
Definition
rapidly dividing, and young cells are more susceptible to radiation injury. eg. small lymphocytes, bone marrow, reproductive cells, immature bone *blood is radiosensitive |
|
|
Term
| is age a factor in radiation injury? |
|
Definition
| Yes, children are more susceptible because their cells growing at a faster rate. |
|
|
Term
| describe short term radiation effects |
|
Definition
| Associated with large doses absorbed in a short time, such as a nuclear accident. No latent period. Immediate damage occurs. |
|
|
Term
| describe long term radiation effects |
|
Definition
| long term radiation effects take years to appear. They are associated with low dose exposures over a long period of time. Repeated low level exposure is linked to cancer, birth abnormalities, and genetic defects. |
|
|
Term
| genetic effects of radiation injury |
|
Definition
| genetic defects are not seen directly in the patient, but by their off spring by way of mutations. |
|
|
Term
| somatic effects of radiation |
|
Definition
| Somatic effects are those seen in the person who was irradiated. These effects can be cancer, leukemia, cataracts etc. The effects will not be transfered to their off spring. |
|
|
Term
| what is meant by a critical organ, and which organs does this include? |
|
Definition
A critical organ is one that if damaged diminishes the persons quality of life.
small lymphocytes, bone marrow, reproductive cells, immature bone.
In the head and neck- skin, thyroid, lens of eye, bone marrow. |
|
|
Term
| what is radiation dose and how is it measured? |
|
Definition
| Does is defined as the amount of energy absorbed by a tissue. It is measured by "radiation absorbed dose" or "rad". |
|
|
Term
|
Definition
| a rad is a special unit of absorbed dose that is equal to the deposition of 100 ergs of energy per gram of tissue. |
|
|
Term
| what is the SI equivalent for the traditional rad? |
|
Definition
the gray (Gy).
1 rad= .01 Gy
1 Gy= 100 rads |
|
|
Term
|
Definition
| does equivalent is used to compare the biologic effects of different types of radiation. The traditional unit of dose equivalent is the roentgen equivalent (in) man, or rem. |
|
|
Term
|
Definition
the product of absorbed dose (rads) and a quality factor specific for the type of radiation.
Each type of radiation has it's own quality factor for this equation.
Rem measures dose equivalent |
|
|
Term
| what is the SI equivalent for the traditional rem? |
|
Definition
sievert (Sv)
1 rem=.o1 Sv
1 Sv= 100 rems |
|
|
Term
|
Definition
| refers to the measurement of ionization in the air produced by x-rays |
|
|
Term
| what is the traditional measurement of exposure? |
|
Definition
|
|
Term
|
Definition
the quality of x-radiation or gamma radiation that produces an electrical charge of 2.58x10^-4 coulombs in a kilogram of air at standard temperature and pressure conditions.
In measuring the R, a known volume of air is irradiated. The interaction of x-ray photons with air molecules results in ionization. The ions are collected and measured. The R is equal to the amount of radiation that produces 2.08x10^9 ion pairs in 1 cubic centimeter of air. |
|
|
Term
| Is there a SI equivalent for the roentgen (R)? |
|
Definition
| no, exposure is stated in coulombs/kg (C/kg). |
|
|
Term
|
Definition
a unit of electrical charge. It measures the number of electrical charges, ion pairs, in one kg of air.
1 R = 2.58x10^-4 C/kg
1 C/kg = 3.33x10^3 R |
|
|
Term
|
Definition
A form of ionizing radiation ubiquitous in the environment.
Naturally occurring background radiation includes cosmic (from the stars) and terrestrial which is emitted from radioactive materials present on earth and in the air.
Artificial radiation is man made, sources include consumer products, fallout from atomic weapons, the nuclear fuel cycle etc. |
|
|
Term
| what adjustments can the operator make to reduce the exposure risk to themselves and their patient? |
|
Definition
- Use the fastest film speed- using F instead of E reduces exposure by 20%. using F instead of D reduces exposure by 60%
- use the smallest collimator- rectangular is best
- use proper film handling, exposure and processing technique- proper technique insures less retakes.
|
|
|
Term
| define risk and state the risk statistic for dental radiation |
|
Definition
the likelihood of adverse effects or death resulting from a hazard.
Dental radiation carries a 3 in one million risk of inducing a fatal cancer. |
|
|
Term
| how do you make the decision to expose your patient to x-rays? |
|
Definition
this must be based off of the individual risk assessment as well as the ADA/FDA guidelines established for x-ray prescribing (pg 54)
X-rays can only be prescribed by a doctor. |
|
|
Term
| what are the two types of filtration used in the dental x-ray tube head? |
|
Definition
| inherent filtration and added filtration |
|
|
Term
| describe inherent filtration in the dental x-ray tube head |
|
Definition
| inherent filtration takes place when the primary beam passes through the glass window of the x-ray tube, the insulating oil, and the tubehead seal. The inherent filtration is approx .5 to 1.0 mm of aluminum. However inherent filtration is not enough because it does not meet the standards regulated by state and federal law. So additional filtration is required. |
|
|
Term
| describe the added filtration in the x-ray machine |
|
Definition
Added filtration is the placement of aluminum disks in the path of the x-ray beam between the collimator and the tubehead seal. The disks can be added in .5 mm increments.
The purpose of the disks is the filter out the longer wavelength, low energy beams- which are non diagnostic in quality and harmful to the patient. |
|
|
Term
|
Definition
a collimator, which is a lead plate with a hole in the middle, is placed directly over the opening of the machine housing where the x-ray exits the tube head. It is used to restrict the size and shape of the beam to reduce patient exposure. The x-ray beam must be collimated to a diameter of no more than 2.75 inches exiting the PID per federal regulations.
A collimator can either have a round or rectangular opening. While rectangular restrict the size more than the round one, it also leaves very little room for operator error and thus increases the risk of needing retakes. |
|
|
Term
| how can the PID assist in radiation protection? |
|
Definition
| The PID is lead lined so it prevents scatter. Also longer PIDs prevent divergence of the beams. |
|
|
Term
| what is a thyroid collar? |
|
Definition
| a lead apron that wraps around the neck to protect the thyroid from scatter during intra oral films. Not used for extra oral films. |
|
|
Term
|
Definition
| a protective apron lined with lead that is draped over the chest and lap to protect the reproductive and blood forming tissues from scatter. Use for both intra and extra oral films |
|
|
Term
| how does faster film assist with radiation protection? |
|
Definition
| faster film has larger crystals, so the exposure on the machine can be turned down. Using faster film is the most effective way of reducing patient exposure to radiation. |
|
|
Term
| what is the distance recommendation for operators? |
|
Definition
| 6 ft away, 90 to 135 degrees to the primary beam. Or use a barrier wall. |
|
|
Term
| what is the position recommendation for operators? |
|
Definition
| the radiographer should be perpendicular to the primary beam or 90-135 angle to the beam. The operator should never hold the film for the patient or hold the tube head during exposure. |
|
|
Term
| what are the shielding recommendations for the operator? |
|
Definition
| Should stand behind a protective barrier that is able to absorb the primary beam. |
|
|
Term
| What are ways the operator can measure their exposure? |
|
Definition
A dosemetry badge, which is worn for a period of time speficifed by the manufacture and then sent in for processing and a report. The badge should be worn at waist level and stored in a non radiated area when not being worn.
Or you could do like Mrs. Fox did and paper clip a film to your shirt and processes it to see if the paper clip shows up as an image. |
|
|
Term
|
Definition
the amount of radiation a body can recieve with little or no injury in a specific period of time.
max dose of an individual exposed to occupational radiation in one year is
5 rems or .05 Sv. |
|
|
Term
|
Definition
occupationally exposed workers must not be exposed to more than the maximum accumulated dose = (n-18)x 5 rems/year
for patients it's .1 rems/year or .001sv/year |
|
|
Term
|
Definition
as low as reasonably achievable.
meaning keep radiation exposure to a minimum when ever possible. |
|
|
Term
| what are the 5 steps of film processing (manual) |
|
Definition
1)development
2)rinsing
3)fixation
4)washing
5)drying |
|
|
Term
| what form can processing chemicals come in? |
|
Definition
1)powder- mix w/ distilled water. This is nice because it takes up less space
2)liquid concentrate- same as above
3)ready to use |
|
|
Term
| what are the 4 basic ingredients in developing solution? |
|
Definition
1)developer agent- also known as reducing agent. contains hydroquinine and elon 2)preservative- sodium sulfite 3)accelerator-alkalai sodium carbonate 4)restrainer- potassium bromide |
|
|
Term
| In which processing solution does the reducing agent belong and what is it's function? |
|
Definition
| Reducing agent, also known as developer agent, belongs in the developer solution and functions to separate the silver from the halide. There are two ingrediants in the developer agent- hydroquinine and elon. |
|
|
Term
| in which processing solution does hydroquinine belong and what is it's function? Is it temperature sensitive? |
|
Definition
| Hydroquinine is found in the developing agent of the developing solution. It generates the black tones and sharp contrasts of the image. It is inactive below 60 degrees F and very active above 80 degrees F. The ideal temperature for hydroquinine to function is 68 degrees F. |
|
|
Term
| In which processing solution does Elon belong and what is it's function? |
|
Definition
| Elon is found in the developing/reducing agent of the developing solution. It generates the different shades of gray in the image. It is not temperature sensitive, but because another ingredient of the developing solution is, it is best used at 68 degrees F. |
|
|
Term
| in which processing solution does sodium sulfite belong and what is it's function? |
|
Definition
| Sodium sulfite belongs in the developing solution and the fixing solution and acts as a preservative by preventing oxidizing. This increases the products shelf life. |
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Term
| In which processing solution does Alkalai Sodium Carbonate belong and what is it's function? |
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Definition
| Alkalai Sodium Carbonate is accelerator in the developing solution. It activates the developing agents, which require a very high pH (alkaline) solution to function properly. |
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Term
| In which processing solution does Potassium Bromide belong and what is it's function? |
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Definition
| Potassium Bromide is the restrainer of the developing solution. It prevents developing, mostly of the unexposed crystals, to prevent over developing which would lead to foggy images. |
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Term
| What are the 4 basic ingredients of the fixer solution? |
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Definition
1)fixing agent- also called clearing agent
2)preservative- sodium sulfite
3)hardening agent- potassium Alum
4)acidifier- acidic acid or sulfuric acid |
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Term
| in which processing solution does sodium thiosulfate belong and what is it's function? |
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Definition
Sodium Thiosulfate is found in the fixing agent (aka clearing agent) of the fixer solution. It removes the unexposed and underdeveloped silver halide crystals making the black portion of the image clearer.
It also "clears" the film so the black image produced in the film by the developer is readily distinguished. |
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Term
| in which processing solution is potassium alum found and what is it's function? |
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Definition
| Potassium alum is found in the fixer solution and is the hardening agent. It shrinks and hardens the gelatin in the emulsion that was softened by the accelerator of the developing solution. |
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Term
| In which processing solution is acidic acid or sulfuric acid found and what is the function? |
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Definition
Acidic acid or sulfuric acid is found in the fixing solution and acts as the acidifier. It neutralizes the alkalinity from the developer because any left over developer could cause the unexposed crystals to continue developing.
It also provides the acidic environment needed for the fixing agent.
This is the ingredient that evaporates and can be tasted after while of being in the dark room. |
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Term
| what are some necessary specs of a dark room? |
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Definition
| must have adequate space (16x20ft) and an exhaust fan for good air circulation. It needs a water source, a room light, a safe light, and an appropriate temperature and humidity. And it must be light tight. |
|
|
Term
| what are the requirements of a safe light? |
|
Definition
must be located a minimum of four ft away from the film to be processed. A low intensity light composed of long wavelengths in the red-orange portion of the visible light spectrum. Must have a filter that removes the short wave lengths in the green-blue spectrum (those are responsible for exposing and damaging film).
Unexposed film must not be exposed to the safe light for more than 2 or 3 minutes. |
|
|
Term
| what is the most common safe light filter? |
|
Definition
|
|
Term
| what temperature should the dark room be and why? |
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Definition
| The dark room needs to stay between 65 and 70 F because the hydroquinine of the developing agent functions best at 68 F. |
|
|
Term
| at what levels should the humidity in the dark room be and why? |
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Definition
| the dark room should stay between 50 and 70% humidity because if levels are too high the film emulsion does not dry. If they are too low static electricity can cause artifacts in the image. |
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Term
| What equipment is needed for manual processing? |
|
Definition
processing tank- holds the 3 insert tanks and the master tank
master tank- holds the insert tanks and the circulating water
insert tanks- one for fixer one for developer
film hangers- also called film racks or processing hangers. Used to hold the film while processing.
stiring rod- both the fixer and developer need to be mixed before use. use either a glass or plastic rod.
thermometer- in the developer to insure proper temp
timer- the time the film is in each chemical is very critical so do not guess, use a timer
apron- you may want a plastic apron to protect your clothes. |
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|
Term
| what are the advantages of automatic processing? |
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Definition
less time- bc there is no wash between fixer and developer. Also automatic chemicals require the film to be in them less time than manual chemicals.
less space- less equipment is needed
temperature, time and drying are all automatically controlled. |
|
|
Term
| what are the component parts of the automatic processing machine? |
|
Definition
- processor housing
- film feed slot
- roller
- film transportation
- developer compartment
- fixer compartment
- water compartment
- drying chamber
- replenishing pump
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|
Term
| what maintenance is required for the automatic processor? |
|
Definition
replenish the solutions (as needed to maintain appropriate levels)
turn the main water line on
clean the rollers (daily w/ a cleaning film and weekly rinse rollers in warm water and then soak for 10-20 minutes)
drain the water at the end of the day |
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|
Term
| what do dark spots on a radiographic image mean |
|
Definition
| developer splashed on it before it was processed |
|
|
Term
| what do white spots on a radiographic image mean? |
|
Definition
| fixer splashed on it before it was processed |
|
|
Term
| what does a finger print on a radiographic image mean? |
|
Definition
| someone touched it before it was dry |
|
|
Term
| if a film is over fixed how will it appear? |
|
Definition
|
|
Term
| if a film is under fixed how will it appear? |
|
Definition
|
|
Term
| what would indicate that there had been a light leak to unprocessed film? |
|
Definition
| a black area on the film (that does not have straight lined edges. That would indicate it wasn't dunked in the developer far enough) |
|
|
Term
| what would over developed film too like? |
|
Definition
|
|
Term
| what would underdeveloped film look like? |
|
Definition
|
|
Term
| how can you maintain quality control with the x-ray equipment? |
|
Definition
| have it inspected by the state to keep it calibrated. |
|
|
Term
| what quality control factors can you implement with x-ray film? |
|
Definition
| make sure it's not expired, stored properly, not exposed to light, not bent. |
|
|
Term
| what quality factors do you need to watch for on the screens and cassettes? |
|
Definition
make sure there are no rips or holes. Make sure cassette stays shut when film is inside.
replace the intensifying screens as needed.
check for dirt or scratches on the intensifying screen. |
|
|
Term
| what quality control factors need to be implemented in the dark room? |
|
Definition
light tight
proper temp and humidity
air flow
dry counters |
|
|
Term
| what quality control factors need to be implemented with the processing equipment? |
|
Definition
machine running properly
temperature sensor working
cleaned when appropriate |
|
|
Term
| what quality control factors need to be implemented with regards to the processing solutions? |
|
Definition
they are used fresh
properly mixed (if concentrate or powder)
tanks are full to the appropriate level
fixer and developer remain separated |
|
|
Term
| what are the components needed for digital radiography? |
|
Definition
computer
monitor
software
sensors
sensor holders
x-ray source
barriers |
|
|
Term
| what are the 3 types of digital x-ray systems? which one does CCD use? |
|
Definition
1) direct digital imaging- sensors (CCD uses this method)
2) indirect digital radiography- storage phosphor
3) optically scanned- traditional radiograph is scanned |
|
|
Term
| can a traditional x-ray machine be used for digital radiography? |
|
Definition
| yes but the kvp and Ma must be turned down |
|
|
Term
| what sizes are digital x-ray sensors available in? |
|
Definition
|
|
Term
| what is the digital sensor connected to? |
|
Definition
| a wire that leads to the computer |
|
|
Term
| what is the most common type of digital x-ray sensor |
|
Definition
| a charged coupling device (CCD) which converts the image into pixels and thus and electronic image is made |
|
|
Term
| describe the pixels of the digital x-ray sensor |
|
Definition
pixels can be compared to the silver halide crystals in traditional film.
When they are energized by the x-ray beams the produce a visible image.
The higher the number of pixels the more definition to the image.
Because pixels are so sensitive to radiation we can greatly reduce the exposure time. |
|
|
Term
| describe storage phoshpor sensors |
|
Definition
storage phosphor sensors use a two step process.
The sensor has a reusable image plate and is wireless, thinner and less rigid than most digital sensors, BUT you have to process them. They are also prone to scratching.
The phosphor material stores the image and then is scanned by a laser into the computer to make the image appear on the monitor. |
|
|
Term
| what are the advantages of digital radiography? |
|
Definition
faster image viewing
reduction of radiation (up to 50% compared to E speed and 80% compared to D speed film
images may be adjusted in the computer (helps reduce retakes)
images take up less space, no mounts needed
ability of remote consultation- emailing images to other practitioners.
easier patient education when you can enlarge the image
reduces cross contamination- (saliva on films going to the front desk, etc) |
|
|
Term
| What type of image adjustments can you make to digital images? |
|
Definition
| contrast, brightness, zoom, colorize, measure, flashlight, swap, reorient |
|
|
Term
| are there any disadvantages of digital radiography? |
|
Definition
yes the sensors are bigger than traditional film and can be hard to place in the mouth.
Techniqually there is less definition to the image, but the human eye is unable to tell the difference.
Sensors cannot be autoclaved.
the system is initially much more costly than traditional radiography. |
|
|
Term
| why must you be super careful with digital x-ray sensors? |
|
Definition
they are just silicon chips and will brake if you drop or abuse them.
they are super expensive- $2,000-$3,000 |
|
|
Term
| describe the optically scanned system |
|
Definition
regular dental film is scanned into the computer which allows for storing and viewing of the image on the computer. Also gives the opportunity for remote consultations.
However it is time consuming. |
|
|
Term
| what are some legal complications of digital radiography? |
|
Definition
| images can be manipulated so this reduces their reliability in a court of law. |
|
|
Term
| how can you maintain asepsis while using digital radiography? |
|
Definition
use barriers on the sensor, keyboard and mouse.
autoclave the sensor holders |
|
|
Term
| which is more environmentally friendly, traditional or digital radiography? |
|
Definition
| digital because it uses no lead or chemicals, no materials for film packages and less radiation. |
|
|
Term
| what is the purpose of a periapical exam? what type of film and what technique is used? |
|
Definition
Examine the entire tooth (root and crown) and the supporting bone
uses periapical film and the parallel or bisecting technique |
|
|
Term
| what is the purpose of the interproximal exam? what type of film and technique is used? |
|
Definition
to examine the crowns, crestal bone and interproximal spaces of the max and mand teeth in the same film.
Bitewing film and the bitewing technique is used. |
|
|
Term
| what is the purpose of the occlusal exam? what type of film and technique is used? |
|
Definition
to examine large areas of the max or mand in one film.
occlusal film and the occlusal technique is used. |
|
|
Term
| what is the complete mouth radiographic series (CMRS) also known as the full mouth series (FMX)? |
|
Definition
intral oral films that show all of the tooth baring areas of the upper and lower jaw (even if the teeth are missing)
used to examine the crowns, roots, interproximal spaces and the bone. |
|
|
Term
| how should film be placed for the bitewing technique? |
|
Definition
| film should be parallel to the crowns of the teeth |
|
|
Term
| what two things could you use to hold the bitewing film in position? |
|
Definition
| a bitewing tab, or the bitewing Rinn |
|
|
Term
| What degree of vertical angulation should you use when taking a bitewing? |
|
Definition
| +10 degrees to compensate for the slight bend in the film when the mouth closes on it |
|
|
Term
| how should the PID be positioned for horizontal angulation when taking a bitewing? |
|
Definition
| the PID should be perpendicular to the curve of the arch and through the contact areas of the teeth. |
|
|
Term
|
Definition
| positioning the PID in a side to side angle |
|
|
Term
|
Definition
positioning the PID up or down.
positive angulation is when the PID is above the occlusal plane pointing down at it.
negative angulation is when the PID is below the occlusal plane pointing up at it. |
|
|
Term
| what happens when you use an incorrect horizontal angulation when taking bitewings? |
|
Definition
| there is overlapping of the interproximal spaces in the image, so its not diagnostic. |
|
|
Term
| what must you do to prepare your patient for taking x-rays? |
|
Definition
films must be ordered by dds.
explain what you're going to do to the pt.
seat the pt, remove glasses, dentures, partials, flippers, lip or cheek rings, place lead apron on pt and make sure Velcro of thyroid collar is secure. |
|
|
Term
| how can you prepare the x-ray equipment for taking rads prior to placing the film in the patients mouth? |
|
Definition
| place all barriers, set the exposure time, move the tubehead away from the wall. |
|
|
Term
| what is the advantage of vertical bitewings? |
|
Definition
| you can see more of the alveolar bone |
|
|
Term
| what should you do when taking a film on an edentulous area? |
|
Definition
| place cotton rolls in place of missing teeth to help stabilize the film holder. |
|
|
Term
| where should you place the film when tori is present in the mouth |
|
Definition
| lingual or palatal to the tori |
|
|
Term
|
Definition
a temperature error; a film has a cracked appearance as a result of being subjected to sudden temperature changes
thin, black branching lines on an exposed film |
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