Radiology Flashcards
What is a radiograph?
photographic record seen on film, produced by passing x-rays through an object or a body.
How should radiation be handled?
carefully
What source of energy does a x-ray machine need to produce x-rays?
A x-ray machine needs electricity to produce an x-ray.
What produces x-rays?
photographic image on dental film, processed for visibility
An x-ray can only be produced if:
plugged into electrical outlet,
the unit is turned on,
and exposure button is pressed.
How are x-rays harmful to the body?
May affect body tissues and cells that carry hereditary materials for future generations.
How do x-rays travel?
X-rays travel in a straight line,at a constant speed, and are invisible.
What can x-rays penetrate?
skin, teeth, and bone
What type of radiation is used in the practice of dentistry?
Ionizing radiation
Why do we use radiology in the dental practice?
provides information not obtained by a clinical exam alone.
How do radiographs in dentistry benefit the patient?
provides early diagnosis and treatment of dental disease
allows patients to maintain a functioning dentition for life
What do proper settings of the x-ray machine ensure?
correct density and contrast of film image.
What are the three variable factors of the x-ray machine settings?
Kilovoltage, milliamperage,and time
What determines the readability of a radiograph?
proper settings
Why should exposure times for kilovoltage and milliamperage be established and posted for each x-ray machine?
dental x-ray machines vary
What is kilovoltage (kVp)?
the ability x-rays have to penetrate
What does the kilovoltage setting affect?
quality of the radiographs produced
Who sets the kilovoltage setting and how?
dental assistant;
by turning the Kilovoltage knob on the control panel, until the needle on kilovoltage meter indicates desired setting.
Who determines the kilovoltage setting and why?
The dentist;
to desired image contrast required for diagnosis of the patient
What does the Milliamperage (mA) and time Setting determine?
number of x-rays delivered from x-ray machine available to strike the film
What must be set properly before the exposure button is depressed?
Three settings; kilovoltage, Milliamperage and time
What determines the darkness or lightness of the image produced?
milliamperage (mA) and time setting
What happens when the exposure button is released too soon?
insufficient amount of x-rays,
and film will be underexposed and too light.
How and how long should the exposure button be pressed?
Firmly until complete preset exposure has occurred
What does an x-ray beam consist of?
Many different energies and penetrating powers
What is a filter?
An aluminum disc placed within tube-head, removes x-rays unable to reach the film.
How does the filter protect the patient?
Prevents nonpenetrating x-rays from stopping at the face.
What is the collimator?
lead disk with round or rectangular hole in the center,manufactured into the end of the cone.
How does the collimator protect the patient?
Limits size of x-ray beam and
Reduces radiation to critical organs.
What does the collimator do?
Limits x-ray beam size to area requested by the doctor.
What is a cone and what is it recommended for?
A long lead-lined cone
recommended for modern dental radiography equipment.
Who exposes patients with radiation for diagnostic purposes?
dental assistant
Why are plastic cones no longer recommended?
scatter radiation produced by x-ray beams passed through the plastic cone before reaching the patient
How much radiation is capable of producing injury?
Any amount
What must be understood about radiation exposure?
potential hazards
What is required to produce radiographs with the least radiation exposure possible?
insight into why all current radiation principals must be used
understanding potential hazards
How many ions are in our bodies?
Trillions,usually unnoticed if a few are ionized
How does tissue damage occur?
Step1: X-rays are absorbed by tissues —>
Step2: molecules in tissues are separated (ionized) into atoms and damage may result.
What are the effects large doses of ionizing radiation?
Sickness, cancer, birth defects, or death
What is the difference between the harmful effects from background radiation (occurring naturally) , and radiation that is man-made( x-rays)?
NONE
How does chronic radiation affect the organs and tissues?
Accelerates the normal aging process of organs and tissues.
What is chronic and repeated radiation exposure, And how does it affect the body?
occurs over a long period of time
may lead to minor percentage of unrepaired effects that accumulate in exposed tissue
What amount of exposure can be difficult to measure?
Very small doses (dental x-rays)
What is the result of repeated exposures?
increases likelihood of many long-term effects includes diseases
Why is unnecessary radiation exposure avoided for all patients?
It’s unknown when an individual receives enough repeated exposures to make an accumulated dose harmful.
Genetic effects of radiation:
Exposure to the reproductive cells causes alterations in genetic code possibly leading to mutation or (changes) in offspring
How does radiation affect cells and which ones are affected?
Not all cells are susceptible to radiation. Can cause changes in cell function or cell death
Which cells are sensitive to x-rays?
Immature cells, rapidly growing cells (developing embryo)reproductive cells, and blood forming tissue cells
The embryo is the most sensitive of all human tissue during which months?
First 3 months of development.
What should you know about the pregnant woman and radiographs?
Considered highly sensitive to radiation, all safety procedures should be strictly performed if it is deemed by the dentist that, risk of not having a radiograph outweigh those of having a radiograph
Who should be screened for pregnancy and properly shield?
women of a childbearing ages
Which two sites near the oral cavity are especially sensitive to radiation?
thyroid gland and lens of the eye
What is the ALARA concept?
Keeping radiation “as low as reasonably achievable”
Why are the thyroid gland and lens of the eye sensitive to radiation and what precautions are taken?
May be exposed to primary beam of x-rays.
thyroid shield on all patients
eye closure during exposure
How is radiation kept “as low as reasonably achievable”or ALARA?
By following basic radiation protection guidelines, repeat radiographs can be avoided, prevents patient and operator unnecessary exposure
Who are the MPD (Maximum Permissible Dose) recommendations for?
General population, occupational worker, and pregnant women
What is the permitted age for a position requiring radiographs and why?
18 on the basis that growing and developing tissues are more susceptible to radiation injury
Who established the MPD and why?
The National Committee on Radiation Protection (NCRP) recommend acceptable levels of exposure to ionizing radiation, not producing significant harmful biological effects.
How can you tell if you’re receiving below the MPD (maximum permissible dose)?
personnel monitoring device or film badge
What does the personnel monitoring device contain for exposure detection,and how are they used?
They contain radiographic film. Measure the amount of radiation received.
Who is subject to x-ray exposure during radiographic examinations?
patient and machine operator
How can radiographs exposures be chosen selectively?
Radiographs precribed by the dentist for specific diagnostic purposes reduces x-radiation doses
Assurance of your clinical competency is required to:
practice on patients unless you’ve received training in exposure, processing skills and techniques from a dentist or structured course
Why should you use correct radiographic techniques for the exposure of dental radiographs?
prevents unnecessary exposure
Why use correct positioning of the patient and films?
Retakes = unnecessary exposure, caused by hasty positioning of patient or film. Ask dentist for assistance if unsure about positioning for a particular view
Why use the paralleling technique, and XCP film holder?
long “cone” paralleling is recommended by the ADA BUTcircumstances or anatomy may dictate other techniques, to be determined by dentist.
Why use “E”film speed?
High film speed =less radiation exposure time needed to create image on film, =less patient exposure.
Do you know if you are using the correct filters and a collimator?
If unsure, ask your x-ray machine service company
Why should you choose the number and size of film conservatively?
Only use number of films necessary to view teeth of interest if anatomy and cooperation permit, Larger size films decrease number of films, and patient exposure
What does appropriate shielding include?
Aprons, thyroid shield, panoramic shields
Why does the patient close their eyes during a radiograph?
increases eye protection, which may be exposed to the primary x-ray beam.
Long open-ended, lead-lined cones are recommended vs.
Pointed plastic cones due to scatter radiation from x-ray beams penetrating the plastic cone before reaching the patient
15W safelights used in a darkroom may cause:
May cause film fogging if;
too close to work area
filter is cracked
or bulb wattage too high
Why shouldn’t you lay films (exposed or unexposed) in the operatory in which you are exposing radiographs:
become damaged if exposed to radiation
should be stored in a lead-lined film storage bin.
To keep exposure time to radiation as short as possible you should?
take safety precautions with every exposure
Where should you stand during a radiograph?
Not in direct line of primary beam
not peeking around corners
not in the room unless behind barrier
if no barriers are available, stand at a right angle 6ft away
Long exposure cords are on units because:
It allows at least 6 feet from patients during all radiographic exposures.
What should you do if you suspect faulty equipment?
Do not use it!
unusual noises, drifting tube-head
immediately report to dentist or supervisor before using again.
Can you hold a patient or film for a patient during radiographic exposures?
NO!
Ask the parent or guardian for assistance if necessary.
Is it ok, to hold the tube-head for stability because it is drifting?
NO!! If it drifts after placement, the unit should not be used until repaired.
What is a personnel monitoring device used for?
To determine if you’re receiving less than the maximum permissible dose (MPD)
Light films: maybe unreadable b/c there’s not enough contrast or detail to be read accurately.
may be caused by:
short developing time,
weak develop a solution,
fixing time too long,
Developing solution temperature low, Film packed backwards in holder.
Dark films: overexposed and caused by too many x-rays striking the film resulting in a un-diagnostic radiograph. may be caused by:
Light leaks developing too long developer concentration to strong developer temperature too high improper fixing paper stuck to film
Fog films: subtle, uniform change in density. Films appear gray and hazy which affects the contrast and detail of the images and may mask dental problems.
may be caused by:
Light leaks in darkroom
film stored in warm or hot environment
out of date film
Stained films: any fluid dropped on an x-ray will cause visible stains or discoloration
may be caused by:
Waterdrops (clear spots)
fixer dropped or improper washing a fixer from films (yellow or brown stain)
developer (dark or black spot)
fluoride on hands (fingerprint artifact)
Improper film positioning
The correct placement is the most critical step for good exposure
Come cutting
Round cylinder not covering them surface after placement and exposure
