QA & AI - Quiz 1

quality assurance (QA)

general management program, scheduling, image analysis outcomes, continuous quality improvement

quality control (QC)

measurement & testing, ensuring optimal images with minimal dose

before a new radiography system is used

when is acceptance testing performed

medical physicist

who performs acceptance testing

verify that hardware meets manufacturer specs & federal safety standards

why is acceptance testing done

periodically

routine monitoring is performed _________ (daily, weekly, monthly, or quarterly)

technologist

who performs routine monitoring

catch immediate or gradual shifts in equipment performance over time

why is routine monitoring done

proactively

preventative maintenance (PM) is scheduled _________ on an annual or semi-annual basis

biomedical service engineers

preventative maintenance (PM) is handled by specialized __________

1 mGy/hour at 1 meter

leakage radiation from tube housing must be limited to _____

control booth

is a secondary barrier that permits observation of patient during exposure

control console

must indicate when tube is energized, make audible sound, and have an illuminated radiation sign during exposure; have visible mAs & kVp readouts

300-400 lbs

radiographic tables must be able to hold how much weight

positive beam limitation (PBL)

automatic collimation that restricts maximum size of beam to IR size

15” (38cm)

SSD (source to skin distance) for fixed diag/fluoro equipment

12” (30cm)

SSD (source to skin distance) for portable equipment

161 LUX

collimator light source must be what luminance

171 LUX

monitors must be what luminance

total tube filtration

manufactures must build x-ray tubes with a minimum amount of total filtration by law. Most important patient protection device for ESE

annually

how often is tube filtration tested

total filtration = inherent + added

total filtration equation

inherent filtration

glass envelope, tube window, oil, mirror in collimator

added filtration

Al or Cu sheets

2.5mm Al equivalent

min. filtration for >70kVp

1.5mm Al eq

min. filtration 51-70 kVp

0.5 mm Al equiv.

min. filtration for < 50 kVp

half value layer (HVL)

thickness of Al that reduces a beam’s intensity to 50%; a measurement of beam quality at a given kVp to ensure that the inherent filtration hasn’t degraded

kVp, generator type, & tube age

HVL changes with _________

exposure field/Light field congruence

x-ray field light must coincide (be congruent) with the light field within 2% of SID and should be tested semiannually

2% of SID

exposure field/ light field congruence must be within what percent

2% of SID

SID indicator (laser or tape) must accurately measure distance from focal spot to the IR within what percent _________

1° of perpendicularity; 2% of SID

beam alignment of CR (perpendicularity) must be within ______ (in inner circle) OR _______ of SID

effective focal spot size

size stated by the manufacturer for the size of the beam origin from a pt’s perspective due to the actual angle of the anode

50%

the EFSS can vary by ______ of the manufacturer’s stated size

actual focal spot size

size of the area on the anode where the electron streams hits the anode

annually

EFSS should be evaluated _______ by physicist and when tube is replaced

pinhole camera

used for EFSS; difficult to use and requires excessive exposure time (for Spatial Resolution)

star pattern

for EFSS; easy to use but limited for FSS less than 0.3mm (Spatial Resolution)

slit camera

for EFSS; **Gold Standard; requires a complex geometric alignment (usually placed 1/3 down from the tube to ensure magnification is enough to see the line (closer it is to the tube, the more magnified) (Spatial Resolution)

½ way btw source & IR

where is pinhole tool placed to get an image the size of the focal spot

½ way btw source & IR - UNLESS too small to read → closer to source to magnify

where is star tool placed

closer to source to resolve the narrow profile of the focal spot

where is tool slit placed

line pair test tool

compares the 3 images at different EFSS (Spatial Resolution)

5%

kVp accuracy needs to be w/ in what percent

oscilloscopes

electronic _______ are the modern way to determine kVp accuracy

annually

how often do exposure timers need to be checked

5%

exposure timer needs to be within what percent

spinning top test

old, but evaluates knowledge of generators & rectification; catches the pulses as individual dots on an image during an exposure (Exposure Timer)

half wave rectified

60 pulses/s, dots = time (s) x 60°

full wave rectified

120 pulses/s, dots = time(s) x 120°

synchronous top

used for 3 phase, high frequency generators that creates a solid arc representing time

exposing IR thru varying thicknesses of Al or acrylic phantoms

how is AEC tested

5%

AEC must be within what percent of baseline output intensity

inserting a heavy lead filter/block

backup timer is tested by

6 sec or 600 mAs

backup timer should terminate the exposure at

10%

exposure linearity must be within _____ for adjacent mA stations

annually

when is exposure linearity tested

5%

exposure & AEC reproducibility: when the same technique (kVp/mAs) is used (but returned to original settings btw exposures) mGy should be the same = they are reproducible within _____ of each other