Exam 1: Lecture 2. Radiology Machine Flashcards
Average range of most machines?
40 to 120 kVp
Because part of the beam is absorbed when using a grid, _____ settings may need to be adjusted accordingly.
Exposure settings. Usually an increase in mA or seconds.
Placement of grids:
- Placed directly on top of the cassette
- Built into the cassette
- Placed under the x-ray table but between the patient and the film
Grid patterns:
Linear and crossed grid (crosshatch)
Most common grid pattern?
Linear
What is meant by the grid ration?
It refers to the height of the lead stripe compared to the width of the interspace.
The higher the ratio, the more _____ will be absorbed.
Scatter radiation
A common grid ratio that is used is?
6:1
When a ____ is used, a grid factor should be included in the exposure calculation.
Grid
The exposure factor is usually increased in the ____?
mAs
Problems that occur when using a grid:
- Using the incorrect focal to film distance
- Incorrect grid positioning
- Incorrect centering or tilting of the grid
Another name for the Potter-Bucky Diaphragm?
Bucky
The bucky is usually located where?
Under the x-ray table or vertically in a wall mounted unit.
Advantages of the Bucky:
- Movable
- Filters scatter
- No grid lines
The bucky is not recommend for _____ units?
Portable
The most versatile type of collimator contains?
Lead shutters and a light source
The _____ helps the radiograph technician to view the field size.
Light source
The light on the collimator also helps technicians to accurately?
Position the patient
Collimator rule of thumb:
Use the smallest field size as possible
Supports the x-ray tube?
Tube stand
Tube stand models can vary from _____ stands to _____ stands mounted on the ceiling.
Tabletop stand to large stands
_____ is used to provide/convert the necessary voltage to provide the electrical potential to accelerate electrons from the cathode to the anode.
High Voltage Circuit
Incoming wall voltage must be changed to?
Kilovolts
What is controlled/set at the control panel?
- Quality (penetrating ability) of the x-rays produced.
2. mA controls the quantity, the amount of electrons produced.
Most standard x-ray machines contain all of the following mechanisms:
- On/off switch
- Voltage compensator/ high voltage circuit
- Low-voltage circuit
- Kilovoltage selector
- Milliamperage selector
- Timer (to control length of exposure)
- Exposure button
- Warning light
Goal of the timer on the control panel?
One thirtieth of a second- reduces chance of patient movement.
Things that fall into the category of Digital Technologies:
- Magnetic Resonance Imaging (MRI)
- Computer Tomography (CT)
- Ultrasound (US)
How does digital radiography work?
- Instead of having a cassette containing a film and screen, the image is received be a image receptor and is converted to an electrical latent image. The electrical image is composed of tiny squares known as pixe.
- The image is then transferred to a computer that is designated for digital radiographs.
- Usually this conversion is done through an analog-to-digital converter (ADC)
Is often used to refer to the computer system that is used to receive, transfer, store, and display the image?
Picture Archiving and Communication System (PACS)
Advantages of digital radiography:
- Images can easily be adjusted
- Less physical storage room
- Files can be easily sent for referral
- Because images can be altered electronically, it can result in fewer exposures.
Two types of digital radiography:
Direct and Indirect
Indirect systems act by converting?
Light to a digital signal
Example of indirect systems?
Computed radiography
The image in the indirect system is stored where and then must be taken to a _____.
On a plate and must be taken to a laser CR reader unit. (CR processor)
The plate in indirect systems must be erased within ___ hrs to prevent the formation of?
24 hrs to prevent artifacts.
Indirect systems: plates should not be exposed to?
Excess scatter radiation
With direct systems, the x-ray is converted?
Directly to an electronic digital signal
Direct systems have better?
Resolution
T/F: Exposure techniques are as important when using digital radiography as they are when using analog radiography.
False
T/F: kVp does not affect the contrast on digital radiographs.
True
T/F: Technique charts do NOT vary greatly for body systems/parts when using digital radiography.
True
T/F: Digital radiography has greater contrast resolution than analog or traditional radiography.
True
Differs from regular radiographs b/c both the x-ray tube and the film rotate around a fixed point called a fulcrum.
Computer Tomography (CT)
Visually provides cross-sectional slices?
CT
Which radiograph is sedation needed?
Fluoroscopy
Provides a moving image that can be recorded?
Fluoroscopy
Which radiograph can there be absolutely no metal objects in the room?
Magnetic Resonance Imaging (MRI)
Which radiograph can provide real time moving images?
Fluoroscopy
Which radiograph gives poor definition of bone?
MRI
Which radiograph does not use ionizing radiation?
MRI
Which radiograph is anesthesia usually needed to prevent patient movement?
MRI
Radiograph that works by creating a magnetic field around the patient?
MRI
MRIs are better than CTs for diagnostic purposes when pertaining to the?
Nervous system
Example usages of CTs?
Intravenous urography of the kidney poles
Which radiograph must you prep the area?
Ultrasound
Radiograph used in cats to detect the size of the thyroid?
Nuclear scintigraphy
Radiograph that can be used to guide needle biopsies?
Ultrasound
Radiograph that uses high frequency sound waves?
Ultrasound
The sound waves in an ultrasound are emitted from?
A transducer.
Consists of a ceramic crystal in between two pinchers
Transducer
The two different modes of an ultrasound:
B mode
M mode
Mode used in cardiology?
M mode
Most common mode?
B mode
Mode that allows for the visualization of movement?
B mode
Mode that movement can be frozen?
M mode
Radiograph that is good for viewing soft tissue?
Ultrasound
Radiograph that uses radioactive isotopes, given as an injection?
Nuclear scintigraphy
Nuclear scintigraphy abnormalities either appear as areas of abnormally high or low _____ activity.
Isotope