Quality assurance in radiology is a series of procedures designed to ensure optimal and consistent operation of each component in the imaging chain .

The result is a high quality radiograph made with low exposure to patients and office personnel .

TO REACH THIS GOAL :

THE quality assurance program includes evaluation of the performance of x-ray machines , manual and automatic film processing procedures ,image receptors and viewing conditions

TO obtain the most diagnostic image with the lowest exposure for patients .

Schedule of radiographic quality assurance procedures :

1-DAILY TASKS :

Check processing by comparing radiographs with reference film ,step wedge or sensitometer and densitometer

Enter causes of retakes in alog

Replenish processing solutions

Check temperature of processing solutions

Run larger roller transport clean-up film through automatic processor

weekly tasks: Replace processing solutions

Clean processing equipment

Clean view boxes

Review retake log

MONTHKY TASKS : Examine photostimulable phosphor plates for

scratches

Check darkroom safe lighting and for light leaks

Clean intensifying screens

Rotate film stock

Check exposure charts

Inspect leaded aprons and thyroid collars for damage such as cracks or tears

YAERLY TASKS : Verify digital sensors with quality assurance

apparatus

Calibrate x-ray machine

DAILY TASKS

1-compare film radiograph with reference film : Light images may be result from :

1-deplation of processing solutions

2-cold solutions

3-insufficient developing time

4-insufficient exposure time

Dark image may be due to :

1-excessive developing time

2-developer too warm

3-ligh leaks

4- increase exposure time

So comparison of daily images with reference one may reveal problems before they

Interfere with the diagnostic quality of the image

There are two methods more accurate than a reference film but require additional time and equipment to perform.

2-SENSITOMETER AND DENSITOMETER : IT IS the most accurate method of tasting film processing solutions

Sensitometer expose the film to calibrated light exposure

After processing ,densitometer is used to measure the optical density of each step in the test pattern of the film exposed by sensitometers

A change in density reading from day to day indicate a problem in the darkroom .

3-ENTER FINDINGS IN RETAKE LOG : Another simple and effective method to reduce no. of faulty radiographs .all errors are recorded so it quickly reveals the source of recurring problems .

4-REPLINSH PROCESSING SOLUTIONS :

At the beginning of each day work , the processing solutions should be checked and replenished if necessary .

4-check temperature of processing solutions :

The optimal temperature before use 68 F(20C) for manual processing and 82F(28C) for automatic processors .

Unheated automatic processors should be located away from windows or heaters that may cause their temperature to vary during day .

Proper temperature regulation is required for accurate time-temperature processing .

WEELY TASKS

WEEKLY TASKS : 1-replace processing solutions :

IT DEPEND UP ON :

A-rate of use of solutions

B-size of tanks

C-whether tank is covered or not

D-temp. of solutions

the results of the step-wedge test help to determine the proper frequency .

2-CLEAN PROCESSING EQUIPMENT:

THE processing equipment should be cleaned for optimal operation .

The tanks of manual and automatic processors should be cleaned .

The rollers of automatic film processors should be cleaned weekly according to manufacture instructions

Both tanks and rollers should be rinsed twice to prevent the cleaner to interfere with the action of the film processing solutions .

2-CLEAN VIEWBOXES:

Should cleaned weekly to remove any particles or defects that may interfere with film interpretation .

3-REVIEW RATAKE LOG :

Should be reviewed weekly to identify any recurring problems with film processing or operator technique this info. Can be used to educate staff or to initiate corrective actions.

MONTHLY TASKS

MONTHLY TASKS : 1-PHOTOSTIMULABLE PHOSPHER PLATES :

IT may be become scratched due to :

in the course of use as light streaks on processed image

It should be inspected for such defects and removed from service .

2-CLEAN DARKROOM SAFE LIGHT :

Film becomes fogged due to :

A-inappropriate safelight filters

B-excessive exposure to safelights

C-stray light from other sources

These films are dark ,low contrast and have a muddy gray appearance

It should be inspected monthly , the glass filter should be A- intact B-with no cracks C-15 watt bulbs

Weather stripping is useful for sealing light leaks under doors .

3-CLEAN INTENSIFYING SCREENS :

It should be cleaned monthly as the presence of scratches and debris result in recurring light areas on the image .

The foam supporting screen should be intact ,capable of holding both screens closely against the film .

If close contact is lost ,the image loses sharpness .

4-ROTATE FILM STOCK :

X-ray film should be stored in A- a cool and a dry facility B- away from a radiation source

Stock film should be rotated when new film is received so the old one does not accumulate in storage .

The old film should be used first but not after its expiry date .

5-check exposure charts :

Each month ,inspection should be done of exposure tables listing peak kilo voltage (kvp) ,mill amperes (mA) and exposure time for making radiograph of each region of the oral cavity that posted by each x-ray machine .

Typically ,the (mA) is fixed , the (kvp) is fixed usually 70 kvp . And the exposure time is varied accord. To the pt. size and location of the area of interest .

6-CHECK LEADED APRON AND COLLARS:

It should be visually inspected for evidence of cracking by a fluoroscopic examination performed by qualified individual.

Cracking can be caused by :

A- folding the shields when not in use

B-from a hook or draping them over a handrail .

YEARLY TASKS

YEARLY TASKS : 1-DIGITAL SENSORS :

Digital sensors and PSP plates should be checked yearly for signs of image degradation .

Failing sensors may reveal loss of sensitivity ,contrast resolution ,or spatial resolution .

Phantoms designed for this purpose are available to aid in such testing .

A radiographic phantom was constructed that contains a calibrated step wedge for measuring dose response, an etched pattern of slits in a metallic background for measuring the spatial resolution in line pairs per millimeter, and 2 rows of wells of varying diameter and depth in an acrylic background for contrast-detail analysis..

IT provides a method of assessing a digital intraoral imaging system by measuring the sensitivity and dynamic range, the contrast/detail detectability and the spatial resolution.

2-CALIBRATE X-RAY MACHINE :

The x-ray machine should be calibrated annually , the following parameters should be measured :

1-x-ray output :

A radiation dosimeter should be used to measure the intensity and reproducibility of radiation output .

2-collimation and beam alignment :

The field diameter for dental intra-oral x-ray machines should be no greater than 2.75 inches .

PID should be closely aligned with the x-ray beam

For panoramic machines , the beam exiting the pt. should not be larger than the film slit .

THIS MAY BE TESTED BY :

Taping the dental film in front of and behind the slit ,both films are exposed and processed and realigned

The exposure of the film in front of the slit should be comparable in size to the film exposure behind the slit.

Service is required if the front film exposure is larger than or not well oriented with the film exposure behind the slit .

3-beam energy :

The kvp should be measured that ensure that the beam have sufficient energy for film exposure without excessive soft tissue dosage .

Kvp measured by specialized equipment . It should be 70 kvp and 1.5 mm AL and 90 kvp and 2.5 mm AL .

4-TIMER:

Should be accurate and producible

5-tube head stability :

It should be stable , not drifting during exposure

6-focal spot size :

AS it may be enlarged with excessive heat buildup

Enlarged focal spot contributes to geometric fuzziness in the resultant image .

Specialized piece of equipment is required for this test

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