Mammography Equipment Flashcards
Name the five known interactions between x-rays and matter at the atomic level.
Compton effect, photoelectric effect, coherent or classical scattering, pair production, photodistintegration
What type of radiation is produced when a projectile electron striking the target of the x-ray tube interacts with an inner shell electron?
Characteristic or photoelectric radiation.
What is the name given to the negative electrode of the x-ray tube?
Cathode
When compared to stationary anodes, why are rotating anodes necessary?
To avoid the constant bombardment of electron in one spot. This can lead to pitting of the target due to heat buildup in one spot
What are the two common tube-target materials used in analog mammography tubes?
Molybdenum and rhodium
What effect will the decreasing target angle have on the focal spot sizes?
Decrease target angle will decrease effective focal spot.
In mammography, what type of imaging uses very small focal spot sizes?
Magnification
To minimize the anode heel effect, the cathode is positioned at which area of the breast?
The cathode is positioned to the chest wall.
Why is the material of the exit port window of mammography tube so important?
The tube window will filter the emerging beam. It is important that the tube not filter out the low-energy x-ray needed for mammography imaging.
Which target material is best for imaging fatty breast tissue, especially in analog imaging?
Molybdenum
At what exposures does the reciprocity law fail?
Very long and very short exposures especially in analog imaging
What is the maximum and minimum force o compression allowed in mammography imaging?
25-45lb (111-200 N) on automatic; 45lb (200 Newtons) maximum on manual
How will placing the AEC detector under the fatty portions o fa breast mixed with fatty and glandular tissue affect the final radiograph in analog imaging?
The dense areas of the final radiograph will be underexposed if the AEC is placed under the fatty breast tissue in a breast with both fatty and dense tissues. The AEC detector selector should be positioned under the dense areal of the breast.
How will grid use affect contrast and exposure in analog imaging?
Grid use will increase contrast however typically needed increase in technical factors and therefore radiation dose to the patient.
Why is close collimation not used in mammography imaging?
Extraneous light will compromise the perception of fine details.
Generally what is the average SID used in mammography imaging?
The range is 50-80 cm with an average of 60 cm.
Identify the single biggest advantage of using the single-emulsion system in analog mammography.
Improve recorded detail
Why is the toe of the characteristic curve never zero?
Blue dye added to the base, plus chemical fog will always result in a density reading.
In relation to a film with a higher speed, where will the slower speed film be located on a characteristic curve?
A curve with a slower speed will be positioned to the right of the curve with faster speed.
Name two factors affecting resolution and sharpness in analog imaging.
Motion, poor screen-film contact, increase focal spot size, increase OID, decrease SID, characteristic of the screen, relationship between OID and SID
What is the best method of controlling voluntary motion?
Clear communication of instructions to patients.
What is the main controlling factor of image brightness in digital imaging?
Image brightness can be controlled by the processing software, which is a predetermined digital processing algorithim. In any digital image, the user can alter the contrast after exposure.
What is the main controlling factor of image contrast in digital imaging?
Image contrast is controlled by the processing software, which is a predetermined digital processing algorithm. In any digital image, the user can alter the contrast after exposure.
Give two possible post processing options available with digital imaging.
Postprocessing options include:
* Windowing to adjust image contrast and brightness on the monitor. The window width will control the contrast and the window level controls the brightness. * Smoothing the image by bringing the brightness value of adjacent pixels closer together. * Magnifying or zooming all or parts of image * Edge enhancement to increase the brightness along the edges of the structures to increase the visibility of the edges. * Subtraction to remove background anatomy * Image reversal where the dark and light pixel values of an image are reversed (e.g. from negative to positive) * Annotating the image with text or numbers