QAQC: Midterm

FILTRATION

The most important patient protection characteristics of a radiographic imaging system

white x-ray

low energy x-rays is aka

reduce patient dose

primary function of filtration

filter out low energy x-rays

secondary function of filtration

inherent filtration

added filtration

total filtration

3 TYPES OF FILTRATION

inherent filtration

filtration that is a result of the composition of the tube and housing

added filtration

The filtration that is added to the port of the x-ray tube.

total filtration

the sum of inherent and added filtration

0.5

inherent filtration constant

half-value layer (HVL)

Filtration is Measured By:

COLLIMATION

X-ray field must coincide with the light field of the variable-aperture light-localizing collimator

tape measure

Use to measure collimation

marked on the x-ray tube housing

Location of Focal Spot:

Collimation

The restriction of the size and shape of the x-ray beam in order to reduce patient exposure.

Focal Spot Size (FSS)

It principally determines the spatial resolution of a radiographic imaging system

pinhole camera

star pattern

slit camera

FOCAL-SPOT SIZE is measured by:

Pinhole Camera

It is difficult to use

It requires excessive exposure time

star pattern

It is easy to use

slit camera

The standard for measurement of focal-spot size

3 mm

Star Pattern Limitation for Focal-Spot Sizes less than _____

kVp Calibration

Type of calibration that must be done whenever high-voltage generator components have changed significantly.

kVp Calibration

The x-ray generator must be properly calibrated

ion chamber

photodiode

Device used in kVp Calibration

photodiode

Converts light into electron

cutie pie

ion chamber is aka

4%

Variation in kVp necessary to affect image OD & radiographic contrast

Exposure Time

responsible for patient dose & OD

ion chamber

photodiode

Device used in Exposure timer accuracy

EXPOSURE LINEARITY

The ability of a radiographic unit to produce a constant radiation output for various combination of mA & exposure time

dosimeter

EXPOSURE LINEARITY is determined by:

EXPOSURE REPRODUCIBILITY

The ability of a radiographic unit to produce a precisely the same radiation exposure when all the techniques are changed & returned to previous value

1. Select a combination of technique factors & hold them constant for a series of 10 exposure

2. Make a series of at least three exposures at the same technique

factors, having changed technique controls between exposure

Two Methods of Evaluation for EXPOSURE REPRODUCIBILITY:

Film Illuminators

It should be analyzed photometrically

photometer

A device used to measure light intensity at areas of the illuminator

Screen-Film Contact Test

Cassette holders must be examined every month for worn closures, light leaks, and warping.

Screens should be cleaned monthly with commercially available cleaners

Radiographing a wiremesh pattern

Analyzing the image for areas of blur

Method of Evaluation for Screen-Film Contact

Replaced Felt or Foam Pressure Pad

if blur appears

Replaced Cassette

if replacement of foam or pressure pad does not correct the problem

Processor Cleaning

RT removes the transport and crossover racks & cleans them & the processing tanks with appropriate fluids

feed/entrance rack

developer rack

cross-over rack

fixer rack

water rack

dryer rack

RACKS IN AUTOMATIC PROCESSING:

cross-over rack

prevents contamination of developer from fixer

power of hydrogen

pH

90 seconds

Dry-To-Dry Time:

500 films/hr

Processing Rate:

Hydrometer

measures specific gravity

hygrometer

measures humidity

specific gravity

measures the activity of developer

35C / 95F

High development temperature

31C / 87F

Wash water temperature

SCHEDULED MAINTENANCE

Routine procedures that are performed usually weekly or monthly

PREVENTIVE MAINTENANCE

A planned program of parts replacement at regular intervals

It requires that a part be replace before it fails

Non-Scheduled Maintenance

The worst kind A failure in the system that necessitates processor repair

proper program of scheduled and preventive maintenance

Non-Scheduled Maintenance Minimize By:

1.000

specific gravity of water

1.030

specific gravity of developer

10-10.5 pH level

Normal pH level of solution

contaminated

if the pH level of solution decreased 0.4 the solution is _____

oxidized

if the pH level of solution decreased 0.8 the solution is _____

oxidation

loss of electron

replace solution

once ph level is too lo or too high:

over diluted

if the specific gravity is low =

too concentrated

if the specific gravity is high =