Midterm Midterm Test Questions Flashcards by Jayden Bohn

What adjustment is made to control the contrast of an xray image?

kVp

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How does a PSP xray film capture an image?

it stores the xray in a phosphor plate which is scanned

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What is the main advantage of using PSP xray films over traditional xray films?

it reduces the radiation dose needed

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How is a PSP xray film erased?

exposing it to visible light

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Structures that radiation can easily pass through appear ____ on an image

radiolucent

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what is the purpose of the aluminum filter within the tube head?

remove the low energy long wavelength xrays from the beam

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Shorter wavelength xrays have a higher penetrating power- true of false?

True

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Which of the following is a common drawback of direct digital sensor?

Hard & rigid in patients mouth - can be hard to plce

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What is the function of CMOS sensor?

CMOS sensors convert X-ray photons into an electrical signal using an array of photodiodes and amplifiers. The direct digital CMOS sensor senses radiation and automatically saves the image with date, correct orientation, and tooth numbering. The images are available at once, removing the time hitherto spent on developing and setting up traditional x-rays.

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Which of the following conditions can be diagnosed using PA

Bone loss & Root infections

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What type of dental issues can be detected using a panoramic issues?

impacted teeth, jaw fractures, cysts

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A properly exposed PA xray should show?

the entire tooth, crown and root and surrounding bone

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Which imaginary plane passes from the bottom of the eye socket trhough the top of the ear canal?

The Frankfort plane

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What is the average radiation dose of a dental xray?

0.005 mSv

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What factors affect the penetration power of the radiation?

Density of object, distance, wavelength

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What is the main difference between genetic & somatic effects?

somatic - individual
genetic - future generations

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What effects the quantity and quality of xray beam?

Milliamperage & Kilovoltage

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How to answer..

I realize I’m experiencing tooth pain and sensitivity, but do I really need all those x-rays? I heard that dental x-rays are dangerous and cause cancer. Is that true?

The DDS requires radiographs to do a complete comprehensive exam/thorough diagnosis.

Ionizing radiation can be harmful…esp in high doses and long duration.

BUT PSP is a form of digital imaging that requires very little radiation.

We also follow a required safety measures ie: monitor equipment, lead aprons

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Dr. Sait suggested that you take periapicals and bitewings. What is the difference and do I need to have both types taken?

Periapical is a specific xray that show the entire tooth (root tip-crown) & supporting structures.

Bitewings – show max and mand crowns and bone level and are primarily used to detect cavities in between the teeth and to assess bone levels.

Both types are required for the exam today because the DDS will use both types for an accurate diagnosis.

PA’s are typically used for specific concerns (cold sensitvity, swelling, pain etc..)

BW’s are used for an overall exam of all quads to look for decay that cannot be seen in between the teeth.

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Dr. Sait completes an initial visual exam, she would like you to expose a quad 1 molar periapical, a 3.3 periapical, a quad 3 premolar periapical and 4 bitewings using the PSP method.

collect the supplies you will require to expose the requisitioned images. What will you get?

XCP kit – posterior PA, anterior PA, bitewing

6 - Size 2 PSP plates, 1-size 1 PSP plate

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Before you start the procedure, Sandra is looking a bit nervous. She asks you to explain the steps of exposing a periapical.

***set control panel first

Sit upright

Lead apron/heavy!

Position receptor in mouthline up PID

Hold still

Beep

Remove from mouth

Will do it 3 x and 4 bitewings

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Because of your knowledge and skill, all 3 periapical images are diagnostically acceptable!!! What are the characteristics of a diagnostically acceptable periapical?

Contrast, magnification, sharpness, all required anatomy visible

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Identify the teeth that will be present in all 4 bitewings. The patient has a complete dentition.

Right side posterior – 1.8-1.6 & 4.8-4.6

Right side premolar – 1.3 (distal) -1.6 (mesial) & 4.3(distal) – 4.6 (mesial)

Left side posterior – 2.8-2.6 &.3.8-3.6

Left side premolar – 2.3(distal) – 2.6(mesial) & 3.3(distal)-3.6(mesial)

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You process the bitewing images and the right side premolar image is not diagnostically acceptable because the contacts are not open. Describe what closed contacts look like on an image and how can this be corrected.

Closed contacts have overlap. No space between teeth and unable to detect interproximal cavities.

Adjust horizontal angulation to make sure the central ray is directed through the contacts.

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Jim asks “What is produced by the x-ray machine in a dental office?” You tell him it produces:

photons

Jim says he read about x-ray tubes and knows that the negative electrode, or cathode, is the source of electrons to generate x-rays. He asks you to explain how photons, which have no mass, could be produced by the x-ray machine when it is true that the cathode produces electrons. You explain to Jim that the ____________ converts bombarding electrons into x-ray photons.

tungsten target in the anode

Jim knows that the line voltage in a building is either 110 or 220 volts and asks you, “How much voltage is used to generate the x-rays in the x-ray tube?” You tell him it is ____ volts.

65,000 to 100,000

Jim asks, “Which part of the x-ray machine is capable of creating 100,000 volts?” You explain that the ______________ in the x-ray machine accomplishes this task.

transformer

Finally, Jim asks you to explain what happens to the photons when they arrive at the patient, and you tell him that a majority of the photons:

collide with a loosely bound outer-shell electron and give up part of their energy to eject the electron from its orbit. The x-ray photons then lose energy and continue in a different direction and interact with other atoms until all their energy is gone.

Jim is curious about the science one must know and understand prior to studying radiation in dentistry. You tell him:

The physics of the atom

You feel Jim needs to understand the difference between radiation and radioactivity so you explain:

Radiation is the emission and propagation of energy while radioactivity is the process by which atoms or elements decay.

Proofing his science paper, you notice that he states communication media uses high-frequency, longer waves in the electromagnetic spectrum. You tell him:

Communication media uses low frequency, longer wavelengths.

Jim asks, “The conversion of electrons to x-ray photons is confusing. Can you explain it to me?” You respond, “The electrons most often have __________ with the tungsten atoms in the anode target, producing __________ radiation.”

many interactions; braking

Jim is concerned that, from what he has read, scatter radiation is a problem for the dental professional. You explain that there are two types of scatter radiation. The Compton scatter accounts for ____% of scatter that occurs in diagnostic radiography.

She wants to know if radiation can cause cancers, and you tell her that:

all ionizing radiations are harmful and produce biologic changes in living tissue.

She asks you to tell her how much radiation she receives each year as background radiation just as a part of living her life. You tell her the average dose of background radiation received by an individual is ___________ millirads per year.

150 to 300

You tell your friend’s mother that the risk of cancer from dental radiography is approximately 3 in 1 million, which is much less than the risk of spontaneously developing cancer. She seems somewhat taken aback, so you tell her that a 1 in 1 million risk of a fatal outcome is about the same as for riding _____ miles in an automobile.

300

She has heard that she could get leukemia from dental x-rays and asks if that is true. You explain:

The dose of radiation necessary to produce leukemia isn’t anywhere near what occurs in dental imaging.

Further concerned, she asks, “Isn’t there any new development in dental science that will reduce a patient exposure to radiation, and you too?” You tell her, “Yes there is. It is called ______________.”

digital imaging

Finally, she asks how a dental professional decides what x-rays to proscribe. You tell her that when x-rays are properly prescribed and exposed, the benefit of __________far outweighs ____________.

disease detection/risk of biologic damage

Jimmy’s mother suggests that you hold the film in Jimmy’s mouth while she makes the exposure. You tell Jimmy’s mother that:

the dental radiographer must never hold the film in place for a patient during x-ray exposure.

Jimmy wants to know why you want to put the heavy “blanket” (lead apron) on him before taking his “pictures.” You explain that:

“It works to limit excessive radiation.”

Jimmy turns his head to watch you leave the room, which changes the alignment of the tubehead with the receptor. As you remind him to look straight forward, you tell Jimmy’s mother that you are trying to avoid:

retaking the image.

Jimmy’s mother asks you to tell her how much radiation a dental professional can be exposed to in a year. You tell her that the current maximum permissible dose (MPD) for occupationally exposed persons is ___ Sv/year.

0.05 Sv/year (50 mSv/year)

Following your explanation of the types of dental images you will be taking on Jimmy, his mother asks, “Is he required to have those every 6 months?” You tell her:

“If we can see between his teeth, we will use our clinical judgement as we monitor for growth and development.”

From an appropriate distance, Monica observes her son wiggling during one of the exposures and asks, “Aren’t you going to retake that one?” You reply:

“Possibly, but we will develop the image to be certain. We avoid retaking images.”

Jimmy asks why you go so far away to “click the button.” You tell him that to prevent x-rays from taking your picture too, you must be at least ____ feet away from the x-ray tubehead.

Anne tells you that while reading her textbook last night, she learned that the kilovoltage peak (kVp) can be defined as the maximum or peak voltage. When she asks you what that means with respect to the beam of photons that exit the x-ray machine, you tell her that the:

quality, or wavelength and energy of the x-ray beam is controlled by the kilovoltage peak. It determines the penetrating ability of the x-ray beam.

Anne then asks you to explain how milliamperage differs from kilovoltage. “If kilovoltage determines the quality of the x-ray beam, then what property of the x-ray beam does the milliamperage control?”

the quantity of photons that exit the tubehead

Anne tells you that although she understands that density is the overall darkness or blackness of an image, she does not grasp what contrast represents. You tell her that contrast refers to:

how sharply dark and light areas are differentiated or separated on an image

You ask Anne to describe the inverse square law. She responds, “The intensity of radiation is inversely proportional to the square of the distance from the source of radiation.” You respond,

“You are correct!”

You ask Anne, “To what does the quality of an x-ray beam refer?” She correctly responds:

“The energy, or penetrating ability of the x-ray beam.

You ask, “If quantity refers to then number of x-ray photons and quality refers to the energy of each photons, then what is intensity?” Anne answers: “Intensity is defined as the product of the quantity (number of x-ray photons) and quality (energy of each photon) per unit of area per unit of time of exposure.” You respond:

You are correct!

You ask Anne, “If you were to increase the milliamperage setting, what effect would it have on a dental image?” She responds correctly

It would darken the image.

You ask her to name the three characteristics of radiation. Anne replies, “Quality, quantity, and intensity.” You tell her:

You are correct!

Kim asks how she will be able to tell that an exposure has been made, and you tell her the exposure light turns ______ and the beep ______ when the x-ray exposure is completed.

off; stops

Kim says that she always thought the patient held the dental x-ray film in position using a finger, and you tell her a __________ is a device used to hold and align intraoral dental x-ray films in the mouth.

film holder

Kim asks you what you are using as a film holder, and you tell her that you are using a Stabe Bite-Block, which is a:

disposable Styrofoam bite-block.

After several films have been processed, one of the supervisors tells you that a few of the images are light. You know that the exposure times were set properly, and a quick check reveals the films have not been placed backward, so you suggest to Kim that she:

makes sure she holds the button down until the end of the beeping sound.

Noticing a small certificate affixed to the x-ray machine, Kim asks, “Has this thing been repaired, or what?” You assure her, “No, that is the registration certificate showing the x-ray machine has been inspected and monitored, which our state requires.” Prior to ___________, however, no federal standards existed for the manufacturer of dental x-ray machines.

1974

Kim is thinking of volunteering with the dental students at a local nursing home. She wonders how they will get dental images on the residents. You tell her:

Some intraoral units are portable and allow for exposures outside of the dental office in sites such as nursing homes and mobile clinics.

In order to use the digital imaging system, the office will need:

a computerized imaging system.

Which of the following is/are true of a system using a CCD?

The CCD is an image receptor found in the intraoral sensor

The typical exposure time required to produce an image for digital imaging is __ impulses.

The CCD:

contains a silicon chip with an electronic circuit embedded in it.

For infection control purposes, the CCD sensor:

must be covered with a disposable barrier or sleeve.

One of the topics discussed is radiation exposure. You learn that exposure times for digital imaging are ____________than those for conventional radiographic imaging.

50-90% less

The first intraoral film container you examine contains size 1 periapical film. This size film is used primarily to examine:

anterior teeth in adults.

Some of the film is D-speed film, some is E-speed film, and the rest is F-speed film. Which of the following statements is true concerning these film speeds?

Use of current F-speed films will reduce the radiation dose to the patient in comparison with that from D-speed films. F-speed film requires 60% of the exposure time of D-speed film and has comparable image contrast and resolution. F-speed film is a faster film because of larger halide crystals and an increased amount of silver bromide in the emulsion. The American Dental Association (ADA) and the AAOMR currently recommend the use of F-speed film.

Which of the following film sizes is appropriate for panoramic imaging?

5 × 12-inch film

Some of the film in the provided supply is duplicating film. Duplicating film differs from intraoral or extraoral film in that:

duplicating film has an emulsion on one side of the film only. duplicating film is not exposed to x-rays. Duplicating film has an emulsion on one side only. The emulsion side of the film appears dull, whereas the side without the emulsion appears shiny. Unlike intraoral and extraoral films, duplicating film is used only in a darkroom setting and is not exposed to x-rays.

Duplicating film should be stored and protected:

in areas that are adequately shielded from radiation. in a cool, dry place.

To demonstrate the different layers of a film packet, you open one for the students to view. There are four component parts to a dental film. The piece of flexible polyester plastic is called the ________________.:

film base

On close inspection of the opened film packet, students notice a thin layer attached to both sides of the film. This is the _____________.

adhesive layer

Students know that gelatin is used to suspend and evenly disperse silver halide crystals over the film base, but they are unsure what it provides. You tell them that

it absorbs processing solutions it allows chemicals to react with silver halide crystals

Students want to know which films are advised when the interproximal spaces need to be closely evaluated?

bitewing

Students ask, “During development, what happens to a latent image? Does it go away? Can we simply not see it any longer?” You tell them

“It becomes visible.”

How are photo-stimulable phosphor imaging (PSP) images captured?

PSP plates are coated with the phosphors. These phosphor crystals capture and hold the latent image until it is processed.

What is a latent image?

A transposed image which is not visible until it is processed

Is PSP a digital or non-digital method of exposing radiographs?

Digital

Are PSP plates disposable or reusable?

REUSABLE

Can PSP plates be sterilized?

NO - have barrier around them. which is wiped, disgarded, replaced.

Is there more radiation exposure to the patient using the PSP method or the traditional film method

Traditional film has more radiation exposure to patient

How long does it take the laser scanner to scan the PSP plates and produce an image to the computer screen?

30 seconds to 5 minutes

How are PSP plates stored?

PSP plates should be packaged before use and kept away from ambient light as it can degrade the image

What 3 essential components are needed for a direct digital imaging system?

an x-ray machine an intraoral sensor a computer/monitor

How are direct digital images captured?

a fiber optic cable runs from the sensor directly to the computer once the image is captured it is immediately delivered to the computer

Is there more radiation exposure to the patient using the direct digital method or the conventional method?

conventional method

How long does it take for the sensor to capture the radiographic image and transmit the image to a computer monitor - for digital?

seconds

How are direct digital sensors stored?

They should be hung up so the cord is not dangled and cannot be damaged or bent.

What are the components of an intraoral dental traditional xray film?

1. Waterproof outer package 2. Black paper 3. Film 4. Black Paper 5. Lead foil backing 6. Waterproof outer package

What size of film would you use for..an adult bitewing xray?

Size 2

what is the function for each layer of the dental film?

1. Waterproof outer package - protects the film from saliva and exposure to light 2. Black paper - Shields/protects the film from light 3. Film - where the image is produced 4. Black paper - shields/protects the film from light 5. Lead foil backing - shields the film from secondary radiation that results in film fog 6. Waterproof outer package - Protects the film from saliva and exposure to light

What size of film would you use for... a bitewing xray taken on a child?

Size 0 or 1

What size of film would you use for... a PA xray taken for an adult molar?

Size 2

What size of film would you use for.. an occlusal xray for a child?

size 2

What size of film would you use for.... a PA xray for an adult anterior tooth?

size 1

What size of film would you use for... an occlusal xray for an adult?

size 4

Who is Dr. Edmund C. Kells?

Dr. C. Edmund Kells, a New Orleans dentist, is credited with the first practical use of radiographs in dentistry, in 1896 Kells, after years of exposing his hands to X-rays every day, eventually lost his fingers, hand, and later his arm as a result of cancerous tumors.