Quality Assurance in Dental Radiology

Table of Contents

Quality Assurance In Dental Radiology.

Film Reject Analysis 2.
Reasons for Rejection.

Solving the Problems2.
Operator Technique 2.
Periapical Radiography 2,5.
Bite wing Radiography 2,5.
Panoramic Radiography 2,5.
Cephalometric radiography 2,5.
The X-ray Set 2.
The Image Receptor3, 6, 7.
The Darkroom.3,6,8.
Processing3.
Monitoring Radiographic Processing.

Refrences:

Quality Assurance In Dental Radiology1,2, 3,4

Quality assurance has been defined as the organized effort by staff to ensure the production of high quality radiographs providing consistently adequate diagnostic information at the lowest possible cost and with the least possible exposure of the patient to radiation

An adequate quality radiograph is one, which provides the required diagnostic information. However the quality of radiograph depends upon several contributory factors. Where the practioners is in any doubt about the reasons for poor radiographic quality It is helpful to systematically target the problem areas. This is achieved by carrying out a film reject analysis.

Film Reject Analysis 2

A subjective evaluation of film quality, which involves keeping a record of radiograph, produced in the practice in particular the poor quality or rejected radiographs.

A simple reject log such as that illustrated below

illustration not visible in this excerpt

This reject log kept in the surgery and filled in as the films are viewed will supply a great deal of useful information in a simple and effective manner.

It is sensible to keep separate logs for Dental films and screen films as each has different problems. After an appropriate period of time perhaps after about a hundred films a total numbers are added up to give both an estimate of the reject rate and basic information about the major problems.

Using this possible underlying causes of poor quality can be identified and you can investigate the corrective action using the below information.

Reasons for Rejection

Possible causes Remedy to Each particular Fault

1. Film too dark

a) Processing Fault

- Developer concentration Dilute or change chemicals

too High

- Developing Time too Adjusted as necessary

Long

- Developer temperature Adjusted as necessary

Too high

b) Excessive X-ray exposure

- Incorrect exposure set Adjusted and repeat examination

- Faulty timer of X-ray Arrange service and repair of faulty

set timer of X-ray Set

c) Fogged Film

- Light leak in Dark room Check and correct

- Faulty safe light Inspect safe lights visually,

Do Coin test and correct any

Fault detected

- Old film stock Discard film

- Poor film storage Discard film and reaccess

Storage facility

- Light leak in cassette Check hinches and catches

Of cassette and repair or

Replace if required

2. Film too Pale

a) Processing fault

- Over diluted developer Change chemicals

- Inadequate development Adjust as necessary

Time

- Developer temperature Adjust as necessary

Too low

- Exhausted developer Change chemicals

- Developer contaminated Change chemicals

By fixer

b) Inadequate X-ray Exposure

- Incorrect exposure set Adjust and repeat

- Faulty timer on X-ray set Arrange service for repair

Of faulty timer of X-ray set

3. Low contrast

a) Processing fault

- Over development(plus Check development and

Dark films) time/temperature relationship

- Under development(plus Check development and

Pale films) time/temperature relationship

- Developer contaminated Change chemicals

By fixer

- Inadequate fixation time Adjust as necessary

- Fixer exhaustion Change Fixer solution

b) Fogged film

- See above See above

4. Unsharp Image

- Patient movement Assess and instruct

Patients carefully

- Pure patient positioning Greater care in

(In Panoramic radiography) Positioning with full

use of aids for position-

ning available on equipment

- Poor Film/Screen contact Check Hinches and catches of

Cassette and repair or replace if

required.

5. Poor positioning

- Film incorrectly positioned Use film holders for intra oral

Or film movement Radiography when possible

- X-ray Tube incorrectly Use film holders with extra oral

Positioned beam aiming device attachment

- Patient incorrectly placed Greater care in positioning with

(Panoramic radiography) full use of aids for positioning

available on equipment.

Solving the Problems2

The following areas are targeted when quality of radiographs is tested with reject analysis

- Operator Technique
- The X-ray Set
- The image receptor
- The dark room environment and
- Processing

Operator Technique 2

Even with the state of the art X-ray equipment and a perfectly equipped dark room, useless radiographs can still be produced because of poor radiographic technique. The most common and important problems in intra-oral radiographic technique are bending of the film leading to distortion, misdirecting the X-ray beam leading to distortion and overlapping of important areas. ‘coning off’ the film due to incorrect tube position and not maintaining the film in a correct relationship to the area of interest. All these problems can be minimized by using film holders, as recommended in correct guidelines to the profession. The most effective film holders consist of a rigid backing to prevent bending of the film and image distortion .A bite section to ensure the retention of the film packet in the correct position and an extra oral beam aiming device to eliminate coning of and to ensure that the beam is directed correctly.

Periapical Radiography 2,5

The most practitioners take periapical radiograph using the bisecting angle technique. Inevitably this technique is subject to many errors because of the wide variation in shape and size of mouths and the lack of precision in tube positioning. Various designs of film holders are commercially available but the rinn XCP system of film holders are probably the best known, the system consists of bite blocks, Beam aiming rings and steel connector bars. They are assembled in a number of ways to cope with different areas of mouth.

In the paralleling technique the film is invariably at a greater distance from the teeth than in the bisecting angle technique so a long X-ray source to skin distance is recommended to avoid unacceptable blurring of the image. The 20 cms distance found on all new dental X-ray sets is adequate for this purpose.

Quality standards for periapical radiography 5,6

A: Evidence of optimal image geometry

- There should be no evidence of bending of the teeth and the periapical region of interest on the image.
- There should be no foreshortening or elongation of the teeth.
- Ideally, there should be no horizontal overlap. If overlap is present, it must not obscure pulp/root canals.

B: Correct anatomical coverage

- The film should demonstrate all the tooth/teeth of interest (i.e. crown and root[s]).
- There should be 2-3 mm of periapical bone visible to enable an

assessment of apical anatomy.

C: Good density and contrast

- There should be good density and adequate contrast between the enamel and the dentine.

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