Rad Physics

huskerfansanfran49's version from 2015-05-07 13:05


Question Answer
What can happen as the X-ray tube ages and tungsten deposits coat the tube?Filtration
What is the most common cause of x-ray tube failure?Electrical Arching
When Heat Damage affects the anode, what is compromised in our image?Image Sharpness, and focal spot
Over time, what happens to the filament?It evaporates
What are the two types of Rating Charts?Radiographic Tube Rating Chart and Anode Cooling Chart
For a 3 phase 12 pulse (High Frequency unit) what number is used?1.41
For a 3 Phase 6 pulse what number is used ?1.35
For a Single phase, what number is used?1.00
A separate rating chart must be used for each focal spot size T or FTrue
What is Thermal ShockHeating up a cold anode tube causes it to crack
To extend tube life, what ratio of factors can we use?High kVp and low mAs
Higher kVp and Low mAs do what for patient exposureLower it

Tube Quality Control/Exposure Timer/HVL/mALinearity/kVp/Exposure Reproducibility

Question Answer
What is Quality AssuranceManagerial Philosophy that encompasses all aspects of patient care, image production, and image interpretation
What is Quality control?calibration and monitoring of equipment
When checking exposure timer, what tools are used?Photodiode device or Ion Chamber
What was the older method of the Exposure Timer?Spinning up test
How does mA linearity work?uses two adjacent mA station to determine accuracy and they must be within 10% of each other
How does Exposure Reproducibility work?10 Exposure made with same technique in able to ensure same exposures everytime
How is Exposure Reproducibility calculatedThe average of the 10 exposures are calculated, then each exposure is checked against the average
What does the Half Value Layer determine?Thickness of absorber material(usually aluminium)
The Half Value Layer is the only true measure of what?Actual penetration capability of x-ray beam
What are two ways to raise Beam penetration in Half Value Layer?Adding Filtration, and Increasing kVp
What tool is used in the half Value layer?Ion Chamber
Explain the HVL testBaseline exposure taken with no absorber, Exposures taken with increasing absorber until less than 50% of the original exposure
What percentage of X-ray beam attenuation are we looking for in HVL test?50%
How is kVp calibration done?Ion chamber or Done by physicist using kVp meter
What tools are used for kVp calibration?Ion chamber or Photodiode

Tube Quality Control cont.

Question Answer
What can cause Collimation Errors?Belt or Gear Slippage
What tool is used to determine this?Grid with a metal bead in the center of a plexiglass cylinder
How is distance measured?Tape Measurer (must be within plus or minue 2% of SID
What does focal spot measure?Sharpness or resolution
The greater the resolution, the ____ the focal spotSmaller
In the Focal spot measure, Lines are placed _____ to the Focal Spot dimension being measuredPerpendicular
When testing AEC, rubber blankets are placed on detectors to see if AEC shuts off at _____ ______ or ____ mAsBack up time or 600 mAs
What is the minimum source to table distance of stationary units in Fluoro?15 inches
What is the minimum source to table distance of Mobile units in Fluoro?12 inches
What is the Output guideline for Fluoro Units?10 R/min