Review Chart 2 Flashcards
Dosimetry is used for what?
Detecting radiation
What is the primary factor for radiographic contrast?
kV
What effect would reducing the FFD have?
Number of x-rays reaching the film increases
What are considered the standard tube distances (SID, that is)?
40” and 72”
What is the purpose of the rectifiers?
Changes the current from alternating to direct
Which of the following is the usual tube warm-up technique?
2 exposures with the 2nd using 2 times the mAs
What will reduce penumbra?
Small focal spot
If you want to produce more x-rays, what would you do?
Increase the mA
A decrease in the anode angle would have what effect?
Smaller effective focal spot
Anode heel effect refers to what?
A reduced intensity of the x-ray beam on the anode side of the tube
What is the method of choice for limiting the size of an x-ray beam?
Collimator
Where should compensating filtration be used when taking a lateral thoracic film?
Lower thoracic spine
Added filtration is a term used for what?
Filtration between the collimator and patient
When is the safest time to x-ray a female?
10 days AFTER onset of menses
If a doctor inadvertently x-rayed a pregnant patient and was dumb enough to keep taking retakes until the fetus was exposed to 5 rads, what would probably be the outcome?
No effect
How much lead equivalency do most shielding devices have in them?
1 mm
What x-ray equipment experiences thermionic emission?
A filament
What is the main difference between ionizing and non-ionizing radiation?
Ionizing has a short wavelength and high frequency
How many rems are in a seivert?
100
What is considered a standard SID?
72”
Determine the outcome of a film if the tube distance is reduced from 72”FFD to 40”FFD with the mAs and kV constant?
The 40” film will be darker
What is the value of knowing the heat units of your unit?
To determine the proper density of the film
What does it mean to attenuate an x-ray beam?
Reduce the intensity
An accurate collimator should not allow more than what percentage of the SID of light outside of the exposure field?
2%
A filament is usually made of which metal?
Tungsten
Targets are usually made of which metal?
Copper
Which type of ray in the x-ray beam is the most perpendicular to the patient?
Central ray
What will dissipate the most heat?
Rotating anode
Let’s say that you are considering tubes for spinal radiography…what would you tell your dealer about your desired tube?
“I want my tube to be a dual focus with a rotor.”
What is most helpful in producing a good quality A-P full spine x-ray?
Having the anode toward the cervical
How much inherent filtration can you expect your tube housing and its contents to have?
.5mm
From which of the following does the electron cloud form?
The filament
At a set FFD and film size, the less collimation used the ________ the film will be?
Darker
The shutters of a collimator are made of which material?
Aluminum
The electron cloud is formed by which process?
Thermionic emission
If you are x-raying a 400 pound man’s lumbar spine, how do you save your machine?
Using a decreased anode angle
You have taken an AP lumbo-pelvic film and notice a 2 inch white or very light band extending across the top of the radiograph. The bottom and lateral margins of it are properly exposed. The ischial tuberosities are within 1 inch of the bottom of the film. With this info, what went wrong?
Central ray is too low
Why do we want to filter out as many of the soft rays as possible?
They cause more scatter to reach the film
You’ve taken an AP thoracic radiograph and notice that the upper part of the spine is overexposed. What should you have done to get a better film?
Used a filter for the upper part of the film
Besides indicating anatomy of the patient, what is the advantage of the “Mitchell” marker?
It indicates recumbent or upright position
On a film, you see a wide light vertical band on one side of the film and the patient’s spine is off center toward the left. You say that the patient was properly centered to the grid cabinet. What went wrong?
The film wasn’t pushed in all the way
If you can’t afford digital imaging, what should you get?
High frequency
Radon comes to us in which form?
Alpha particles
Give or take a little, natural background radiation accounts for about how much of our average annual exposure to ionizing radiation?
80%
What is the term for the beneficial effect of radiation?
Radiation hormesis
What is NOT a property of x-ray?
They are stored in matter (NOT TRUE)
How many rads are in a gray?
100
Which unit of measurement is usually used for reporting occupational exposure to radiation?
Rem
What year did BJ Palmer introduce x-ray into the chiropractic profession?
1910
The focal spot size is usually set in conjunction with which of the following?
Low voltage circuit
What would happen if you lengthen the time of an exposure?
You would increase the number of photons hitting the patient
Which primary factor is responsible for the quality of an x-ray beam?
kVp
The mA setting determines what?
Current going through the filament
What would have the least fluctuation in the kV level?
High frequency
What propels the electrons in an x-ray tube?
kV
A tube warm-up procedure should be performed by using how many exposures?
2
Which part of an x-ray tube is the target located in?
Anode (target, stem, roter)
The first place that attenuation of any part of the x-ray beam occurs is at which point?
Anode
The term “thermionic emission” is most closely related to what?
The cloud of electrons at the filament
How many filaments does a dual focus tube have?
2
What is the purpose of the collimator shutters?
Filter the periphery of the beam
Which 3 radiographic projections routinely use compensating filtration?
AP thoracic, lateral thoracic, and full spine
What is the best way to identify a patient’s film?
A flash on label before presenting
When is a fetus most sensitive to radiation?
1st trimester
What body parts are the most susceptible to develop a malignancy from ionizing radiation?
Bone marrow and breast
When comparing films of the same patient, one set taken 3 months ago, you notice the film is too dark and the cervicals are larger than they were 3 months ago. What went wrong?
You took the film at 40” instead of 72” that you used 3 months ago
What is the best type of x-ray equipment to buy?
Dual focus tube with a tungsten target surrounded by copper with the same anode angle of 14 degrees and tungsten filaments
If you wanted to reduce penumbra, what should you consider doing?
Use a smaller effective focal spot
What is the most effective way to reduce secondary radiation?
Collimation
A decrease in the anode angle would have what effect?
Smaller effective focal spot
What is the anode heel effect?
A reduced intensity of the x-ray beam on the anode side of the tube
Inherent filtration adds how much aluminum equivalency?
.5mm
The first radiographic print was of what body part?
Hand
What sets the current going through a filament?
mA control
What occurs to cause ionization?
Removal of an electron from an atom
A step up transformer will have which effect?
Increase the volts
On the average, what accounts for over 50% of the typical person’s radiation exposure?
Radon
What device is used to detect and measure radiation?
Dosimeter
What is the most helpful in producing a good quality AP full spine x-ray?
Have the anode toward the cervical
What is the minimum anode angle that can be used if you were going to take a 14.36” full spine film?
14 degrees
Which type of radiation always travels at the speed of light?
Electromagnetic (has no mass and travels in packs “photons/quanta”)
X-ray is produced at which tube part?
Target
How many electrodes does the usual x-ray tube contain?
2 (anode+ and cathode-)
Of your body’s systems, which will require the most radiation in an acute blast to screw it up?
Nervous system
Radon gas accounts for what percentage of the annual dose of natural background radiation?
55%
