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104 Cards in this Set

  • Front
  • Back
True or false. With any fluoroscopic unit, moving the body part away from the tube and towards the image intensifier will decrease magnification.
True
What are the processes when altering the pixel values and returning them to their original value on a CT image?
convolution and deconvolution
The man that gets credit for inventing CT is:
Hounsfield
First generation CT scanners used ______ type detectors.
Crystal
What is it called in CT when the sectional data can be combined to produce slices in different directions or create 3-D images?
Reformation
The type of CT slice that is an AP projection of the body is:
Coronal
The type of CT slice that shows a lateral projection of the body is called:
Sagittal
In a cardiovascular imaging suite, when doing a sequence of several rapid exposures combined with fluoro, it is a good idea to consult the _________ in order to insure that yoru study will not cause heat damage to the tube.
Percent duty cycle chart
In order to check if a single exposure could damage a tube you should check the:
Tube rating chart
After finishing a sequence of rapid exposures in a cardiovascular imaging room, you should check the _________ before starting a second sequence to insure that your tube does not overheat.
Tube housing cooling and anode cooling charts
Conventional radiography generators generally operate at _______ mA and ________ kVp than vascular imaging generators.
Lower mA, higher kV
In order to better visualize a vein injected with a contrast agent, it is best to use ________ kV and _________ exposure time.
Low kV, short exposure time
True or false. It is necessary to pre-warm contrast agents before placing them in pressure injectors.
True
When doing biplane imaging, the intensifier that requires a crosshatched grid to filter the increased scatter is the intensifier receiving the _________ projection.
AP
What is the rotation of the axis of rotation of a spinning nucleus?
Precession
In a static magnetic field, all protons of a given isotope will rotate with exactly the same frequency. This frequency is known as:
Larmor frequency
Protons that are ____________ have excessive energy, which they emit as electromagnetic radiation in the RF range.
Anti-parallel
Why do hydrogen atoms react well to a magnetic field?
They have a single proton nucleus.
The ratio between a magnetic moment and the moment of inertia in a nucleus placed in a magnetic field is called it's:
Gyromagnetic ratio
Since the human body would not send off RF radiation in a stationary magnetic field, it is necessary to:
Pulse the stationary field with the use of gradient coils.
For the best MRI imaging of small areas like the TMJ, it is best to use what type of coils?
Surface
Irregularities in a magnetic field created by outside ferromagnetic materials are compensated by:
Shim coils
What is the Hounsfield unit for water?
Zero
What is the Hounsfield for bone?
+1000
What is the Hounsfield for air?
-1000
What are the two cryogens used in a superconductive magnet?
Helium and nitrogen
In MRI, the type of coils used for the X, Y, and Z axis are :
Gradient coils
Helical scanners were made possible by:
Slip ring technology
True or false. Added filtration is not a neccessary component to a typical CT scanner.
False
The relationship between voltage, current and resistance is called:
Ohm's law
V=
I x R, ohms x amps, Resistance x Current
an ohm is a unit of :
Resistance
an amp is a unit of:
Current
If the voltage is increased, then the amperage is decreased at the same ratio to maintain the same wattage. This is the :
Transformer law
____________ is the force or electrical pressure that produces the electron movement.
Voltage
The unit of power is the _______.
Watt
Watts =
Amps squared x resistance and volts squared/resistance
Transformers operate by means of __________ induction.
Mutual
Transformers can only work with _____ current.
AC
What type of transformer has a fixed number of coils with output taps? It is used to control the voltage to a step up or step down transformer.
An autotransformer
Autotransformers use ______ induction.
Self
___________ induction occurs when two coils are placed in proximity and a changing current is applied to the primary coil.
Mutual
___________ induction is a single coil of wire supplied with a changing current. The process by which the current is reversed (AC) induces a change in the current at another portion of the coils.
Self
____ motors require a commutator ring to operate.
DC
____ motors require slip rings to operate.If
AC
Induction motors operate on ____ current.
AC
If ___________ are oriented in the same direction, they will exhibit a uniformly strong magnetic field. This is a magnet.
Dipoles
___________ radiation only occurs when the incident electron interacts with an inner shell electron.
Brehmsstruhlung
The energy of Brehmmstruhlung radiation can range from:
Zero to the max kVp level
____________ interactions only occur above 70 kVp.
Characteristic
___________ interactions only occur when the incident electron interacts with an inner shell electron.
Characteristic
How may millimeters are in a meter?
1000
How many centimeters are in a meter?
100
How many meters are in a kilometer?
1000
__________ is the complete or partial loss of x-ray energy within the patient.
Attenuation
What are the four factors that impact attenuation:
xray energy, tissue thickness, tissue density, atomic #
Which generation CT scanner was the first with a fan shaped beam?
2nd
Which generation CT scanner had 30 detectors?
3rd
Which generation CT scanner was created due to a contract awarded by the U.S. Institute of Health?
4th
Which generation CT scanner was created for cardiac units?
5th
Which generation CT scanner was helical/spiral?
6th
Which generation of CT scanner was MSCT?
7th
______________ is the distance between scan sections.
Section interval
CT operates at _____ kVp and _____ mAs.
120 kVp and up to 1000 mAs
What is the relationship between Gauss and Tesla?
1 Tesla = 10,000 Gauss
In Nuc Med, as SID increases detail ____________.
Decreases
________ coils are placed within the coils of the stationary magnet to compensate for irregularities.
Shim
________________ are RF coils. They may serve as both the transmitter and receiver of signal.
Body and surface
_____________ coils can be operated to emit pulse sequence for spatial localization of anatomical section.
Gradient
The process of layering cryogens is ____________.
Ramping
Superconductive magnets use liquid cryogens. ___________ is used in the inner deward and _________ in the outer.
Helium, nitrogen
What is the formula for computing heat units?
HU = kVp x mAs x Rectification constant x # of exposures
What is the rectification constant for single phase?
1
What is the rectification constant for 3 phase 6 pulse?
1.35
What is the rectification constant for 3 phase 12 pulse?
1.4
During what interaction does the incident photon loses some or all of its energy when it impacts with an inner k shell electron and removes it from orbit. The filling of this vacancy produces a characteristic x-ray of low energy.
Photoelectric effect
Characteristic interactions occur at the:
Tube
Photoelectric effect occurs at the:
Patient
Name the interaction. When an incident photon collides with an outer shell electron, the original photon continues in a different direction minus the energy that it took to remove the electron from its orbit.
Compton's
What is the atomic # for molybdenum?
42
What is the atomic # for lead?
82
What is the atomic # for tungsten?
74
True or false. As kVp increases, the efficiency of photon production also increases.
True
The type of radiation that is produced by an incident electron interacting with the nuclei of a target atom is:
Brehmmstruhlung
True or false. Attenuation is absorption or scatter.
True
The type of x-ray interaction that never varies in energy levels but depends on the atomic # of the anode is:
Characteristic
When viewing an x-ray spectrum for any exposure, most of the x-rays will have a peak energy level of:
about 1/3 of the kVp setting on the control panel
What happens to the peak overall average energy of the beam when filtration is added to the beam?
Increases because the weaker x-rays are removed
What happens to image detail when SID is increased?
Detail increases
Moving the image intensifier towards the body part (increasing the SOD) will have what type of effect on magnification and detail?
Magnification decreases and image detail increases
What effect does using an air gap technique have on image detail?
Decreases
_________ is the lack of detail caused by focal spot size.
Penumbra
True or false. Magnification is a distortion of an image in at least two different directions.
True
What factor impacts beam quality?
kVp
What is the reason we don't use small focal spots on all exams is?
It increases exposure time on larger patients
The term used to indicate the conversion of AC current into DC current before the current is applied to an x-ray tube is:
Rectification
_________ is the force or electrical pressure that produces electron movement and current flow.
Voltage
The unit of electriccal power is the ______.
Watt
True or false. An autotransformer can operate on both AC or DC current.
False, only AC
What type of motor is used to drive the anode in an x-ray tube?
Alternating current induction motor
True or false. Rectification of alternating current to pulsating direct current is done using diodes or semiconductors.
True
The type of rectifier used a long time ago that was similar to an x-ray tube except that it operated at lower energy levels was called a _________.
Valve tube
How many diodes are used with a half wave rectified circuit?
1
A device that utilizes several coils of wire with current passing through them in order to create a magnetic field that can be turned on and off in order to repel or attract a magnet is known as:
solenoid