Quality Assurance and Quality Control of X-ray EQUIPMENT

Quality Assurance and Quality Control OF X –RAY EQUIPMENT

Quality Assurance and Quality Control of X –RAY EQUIPMENT

INTRODUCTION

The term x-ray equipment covers generator, tube, cables, control panel, table, tube stand and bucky.

It is important to ensure that all equipment is working efficiency and accurate records are kept Quality Assurance (QA) of medical diagnostic x-ray equipment means systematic actions necessary to provide adequate confidence to the end-user(s) that a medical diagnostic x-ray equipment will perform satisfactory in compliance with safety standards specified by the Competent Authority.

Quality Assurance and Quality Control of X –RAY EQUIPMENT

INTRODUCTION

Quality Assurance Programme

The goal of QA Program is to ensure the accuracy of the diagnosis.

The minimum radiation dose should be delivered to the patient to achieve the objective of the diagnostic or interventional procedures.

Quality Assurance and Quality Control of X –RAY EQUIPMENT

INTRODUCTION

QA programme begins with the performance evaluation of diagnostic x-ray equipment at the manufacturing stage and then acceptance testing after the installation of X-ray equipment at user’s institution(s) to ensure its conformity with the specifications.

The QA tests should be carried out thereafter at regular intervals (periodicity-once in two years) and also after repairs of the equipment or when equipment malfunction is suspected.

Quality Assurance and Quality Control of X –RAY EQUIPMENT

Objective / Aim of Quality Assurance (QA) To provide the technical information and testing routine that will allow simple care, maintenance and testing to be carried out on basic x-ray equipment. To provide an insight into the choosing and accepting of basic x-ray equipment To provide technical knowledge and practical skills to carry out simple cleaning, maintenance and testing on x-ray equipment Optimum image quality of radiological procedures with minimum possible dose to the patient(s)

Quality Assurance and Quality Control of X –RAY EQUIPMENT

Why QA in Diagnostic Radiology?

The routine QA tests are necessary to ensure that the functional performance of the equipment is similar to its baseline values and within the tolerance values as specified by regulatory body These tests should be performed by qualified service personnel(s) at user institution(s).

These tests should be performed at regular intervals (once in two years) and at major repairs of X-ray equipment.

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Choosing x- ray Equipment
• Identify your Need
• General purpose, fluoroscopy, specialised mobile
• Generator (design / output
• To suite power supply
• Alignment

FFD (SID)

• x – Ray Table
• Mechanical
• Electrical

Alignment

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Choosing x- ray Equipment
• Making the Choice
• Establish your specification requirements
• Review manufacturer’s specifications
• Submit your requirements to the selected manufacturers for quotations

Make selection

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Accepetance of New X- ray Equipment
• Specifications of equipment installed are the same as that ordered
• Installation has been carried out as stated in the contract
• Installation is complete and equipment is working efficiency and to your satisfaction
• All accessory equipment has been supplied and is in good order

Operating manual has been supplied and is the correct one

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Quality Assurance Tests for Diagnostic X-ray Equipment

Generator

Radiation output reproducibility (output radiation intensity is the same each time when the same exposure is made because it can affect patient dose and image quality.) Constancy of radiation output at different mA settings Accuracy of kVp

• Accuracy of timer
• X- Ray Tube and High tension (HT) Cables
• Electrical

Tube Support

Mechanical

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Quality Assurance Tests for Diagnostic X-ray Equipment

Generator

A generator is part of the electrical system of an x-ray machine which determines radiation output. Any inconsistency in radiation output will adversely influence the quality of the radiograph The kV, mA and time must be consistent on all settings. Many factors can influence the radiation output.

• The ones to be considered are:-
• Fluctuations in the main electrical supply

Inconsistency or inaccuracies in kVp, mA and time

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Quality Assurance Tests for Diagnostic X-ray Equipment

Fluctuation in Main Electrical Supply Most x-ray units have a mains compensator that automatically compensates for mains fluctuations The Radiographer must always check the mains compensator meter before making an exposure

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Quality Assurance Tests for Diagnostic X-ray Equipment
• Congruence of radiation and optical fields
• Central beam alignment
• Accuracy of Accelerating Tube Potential

Timer Accuracy

• Linearity of radiation output
• Reproducibility of radiation output
• Total filtration
• Radiation leakage through tube housing
• Exposure rate at tabletop

Fluoroscopic image quality parameters

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• X ray–light beam alignment and centring

Improper beam alignment and centring will impact the radiographic image.

The set light field needs to align well with the X ray beam area in order to limit the radiation field to the necessary size and to not miss any parts because of possible misalignments.

Therefore, the objective of this test is to ensure the coincidence and alignment of the collimated light field with the X ray field.

Another aspect is the coincidence of the crosshairs of the collimated light beam with the centre of the X ray beam, which is the origin point of the image

Quality Assurance and Quality Control of X –RAY EQUIPMENT

Congruence of Radiation and Optical Fields The X-ray field must be aligned with the light field so that the operator can accurately position the body part to be imaged If the optical field and radiation field are not congruent, the area of clinical interset may be missed in the radiograph leading to retakes and unnecessary radiation exposure to patients Collimator test tool are used with detector FFD kept 100cm

Quality Assurance and Quality Control of X –RAY EQUIPMENT

Central Beam Alignment

If the x-ray beam is not perpendicular to the image receptor, the image may be distorted. If grid is used, the distortion will be magnified resulting in complete loss of minute details.

Beam alignment test can be done simultaneously with the test for congruence of optical and radiation field Frequency

six months.

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• X ray–light beam alignment and centring

Equipment

An appropriate test object for the alignment of the X ray beam and the light field. Coins or other metal objects may also be used for the alignment test.

A cylinder with an attenuator at its centre, or another test object that can be used to assess the perpendicular incidence of the beam on the image receptor

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• X ray–light beam alignment and centring
• Equipment

Using a commercial test object:

Place the image receptor on a flat surface and set the X ray tube’s axis to be perpendicular to the image.

Position the test object on the image detector with the cylinder in the centre of the light beam crosshairs Set the source to image distance (SID) to be 100 cm.

• Use the light field and the markings on the test object for accurate field alignment.

Make an exposure using exposure parameters 50 kV and 3 mA.

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• X ray–light beam alignment and centring
• Equipment

Using coins:

Place the image receptor on a flat surface and set the X ray tube’s axis to be perpendicular to the image.

Position the image detector at an SID of 100 cm.

Collimate the light beam to a small field on the image detector (e.g. 20 cm × 20 cm). The image receptor area needs to be greater than the light field.

Place metal markers (e.g. coins) at every edge of the light field; mark with coins the corner of the light field Make an exposure using exposure parameters 50 kV and 3 mA

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• X ray–light beam alignment and centring
• Procedures are used for the analysis and interpretation of the test results

X ray–light field alignment:

Measure the distance between the edges of the image and the markers of the test object or the coins.

Centring:

Evaluate the deviation of the light beam crosshairs from the centre of the X ray beam according to the specifications of the test object’s manufacturer.

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• X ray–light beam alignment and centring

Procedures are used for the analysis and interpretation of the test results X ray–light field alignment: The deviation of the X ray field from the light field should not exceed ±2 cm on any side for an SID of 100 cm or ±2% of any other SID.

Centring: The coincidence of the collimator light beam crosshairs with the X ray beam centre should not exceed ±1 cm at SID = 100 cm

Quality Assurance and Quality Control of X –RAY EQUIPMEN

Distances and scales

The aim of this test is to determine the accuracy of the SID indicator of the X ray system.

This test has an important role for radiographic imaging and when dose monitoring software is used, as the distance indication may be used as an input for determining the distance from the focal spot to the entrance surface (skin) Equipment needed

a long ruler or a measuring tape at least 100 cm long.

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Distances and scales
• Procedure is used for the test

Set an SID of 100 cm by using the SID indicator of the system.

Measure the actual SID using the ruler or measuring tape, starting at the focal spot indicator on the side of the X ray tube and extending to the tabletop or surface of the image receptor Record the result.

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Distances and scales
• Analysis and interpretation

Compare the measured value with the SID readout indicator of the X ray system.

The difference between the ruler or tape measurement and the SID readout indicator should not exceed ±1.5 cm Frequency

every six months.

Quality Assurance and Quality Control of X –RAY EQUIPMENT

Image uniformity and artefacts

This test is performed to assess the degree and source of artefacts visualized in digital radiography images, and to ensure that the image is uniform and artefact free Equipment needed

A copper attenuator (1 mm thick or similar) is recommended.

Alternatively, other attenuators may be used, such as 10 cm of polymethyl methacrylate (PMMA).

The attenuator should be large enough to cover the whole image, as well as homogeneous.

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Image uniformity and artefacts
• The test procedure

Place the attenuator in the X ray field.

Set an SID of 100 cm. Note: For computed radiography systems, a larger SID (at least 150 cm) and two exposures may be necessary in order to assess whether the lack of uniformity is attributable to the heel effect.

After making the first exposure, turn the image receptor around its axis, perpendicular to the image plane, by 180° and make a second exposure.

Then, compare the two images.

Place the copper plate at the collimator or place the attenuator at a distance where it covers the whole image receptor area.

• Set the collimator in a way that the entire image receptor is exposed.

Set the exposure parameters at 70 kV and 3 mA

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Image uniformity and artefacts

Analysis and interpretation

Visually inspect the image for artefacts and uniformity. Use a narrow window width to view the image on the appropriate display.

• Record the status of the image.
• Baselines and tolerances
• No visible artefacts or grossly inhomogeneous areas should be observable.
• Frequency

Monthly

Quality Assurance and Quality Control of X –RAY EQUIPMENT

Automatic exposure control constancy The purpose of automatic exposure control (AEC) is to deliver consistent, reproducible exposures across a wide range of tube potentials and to compensate for different anatomical thicknesses.

• Equipment

A copper plate or other attenuator (10 cm of polymethyl methacrylate (PMMA).

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Automatic exposure control constancy
• Procedure

Centre the tube on the image receptor area.

Collimate the beam so that it covers the whole image receptor. The field size needs to be set in a way it covers the AEC sensor(s).

Put the attenuator on the X ray tube or place it at the appropriate distance between the focal spot and the image receptor so that it covers the whole image receptor area Select the exposure parameters according to the local routine or use the parameters applied during the commissioning procedure (e.g. 70 kV). Choose the AEC sensor designated or used earlier for this test. The tube kilovoltage should be kept the same for all measurements.

Make an exposure and record the tube current–exposure time product (‘mAs value’) and the exposure indicator (exposure index) displayed on the operator’s console

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Automatic exposure control constancy

Procedure

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Automatic exposure control constancy
• Analysis and interpretation
• Compare the mAs value and exposure index with the corresponding baseline values.

Baselines and tolerances

The recorded exposure index and mAs values should be within ±25% of the respective baseline values for digital radiography systems and within ±30% for computed radiography systems.

• Frequency

Every three months.

N/B Since the operation of the AEC depends on the generator and AEC system itself, the consistency of the generator should be checked.

Trends indicate that a recalibration of the AEC system by the service engineer may be necessary.

Quality Assurance and Quality Control of X –RAY EQUIPMENT

Automatic exposure control sensitivity AEC is used to compensate for the change of the X ray tube voltage and the thickness of the patient’s anatomical area exposed.

All radiography systems equipped with AEC use AEC sensors, which are usually ionization chambers that determine the amount of photons incident on the image receptor.

Consistent image quality requires that each sensor produce the same output (or at least a consistently different setting if it is set differently) for a given setting and operate in a consistent manne

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Automatic exposure control sensitivity
• Equipment needed
• A copper plate or other attenuator (10 cm of polymethyl methacrylate (PMMA)is used

Centre the tube to the image receptor placed in the bucky.

Collimate the X ray beam to cover the whole area of the attenuator and ensure that the selected AEC ionization chamber is inside the X ray beam.

Slide the copper plate into the X ray tube accessory rail or place the attenuator between the focal spot and the bucky.

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Automatic exposure control sensitivity

The test procedure

Select 70 kV and the central ionization chamber Make an exposure and record the mAs and exposure index values displayed on the X ray system after the exposure. Then select the sensor or sensors that were not tested, and repeat the previous step.

• Frequency

Every three months

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Accuracy of kVp test

(Tube potential accuracy)

The tube voltage is one of the most important parameters that affect both radiation exposure and image contrast The accuracy of tube voltage is critical, since even a minor variation will have considerable effect on the final radiographic image.

This test assures that the accuracy of the tube voltage selected from the operator’s console of the X ray system corresponds to the actual value

The peak potential of the x-ray generator affects quality of the x-ray beam and exposure to the patient.

Assessment of the tube potential ensures that the delivered kVp is close to that set on the equipment by the operator To check that the generator is producing the kVp set on the control panel. This can be carried out by using a kVp meter or a kVp test cassette Tolerance ±5% or ±5 kV

• Quality Assurance and Quality Control of X –RAY EQUIPMENT

Accuracy of kVp test

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Accuracy of kVp test
• Frequency of test
• When the equipment is first installed
• Yearly
• As necessary

Equipment required

kVp meter with a valid calibration and capability of measuring in the 40–150 kV range is used Generator to be tested

Quality Assurance and Quality Control of X –RAY EQUIPMENT

Accuracy of kVp test

Whenever the tube potential accuracy is measured, the same indicator of the instrument (e.g. practical peak voltage) or the average or maximum of the peak tube voltage) should be consistently used.

A lead plate or apron of thickness 0.35 mm, 0.5 mm or 1.0 mm is needed if the image receptor is not removable from the bucky Procedure

• Place the sensor in the middle of the x-ray beam at a FFD (SID) of 100cm
• Collimate to a standard area sufficient to cover the sensor
• Take reading at 10kVp intervals from 50kVp to the maximum kVp available
• Use a standard mA and time throughout

Repeat this procedure for each tube focus available

Quality Assurance and Quality Control of X –RAY EQUIPMENT

• Accuracy of kVp test
• Evaluation
• Compare each kVp reading with the appropriate kVp setting
• The measured kVp must be within + or – 5kVp or 5%
• Action

If the measured kVp do not fall within the acceptable limits, call an x-ray engineer

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Accuracy of Timer test

If the exposure time of the x-ray unit is not in order, the radiograph can be under exposed or overexposed.

For this, absolute timer method is adopted by measuring set and measured time with digital timers.

• Tolerance: Accuracy of exposure timer % Error ± 10 %
• Frequency of Test
• At the start of a quality control program
• Yearly

As necessary

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Accuracy of Timer test

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Radiation output Reproducibility Test – obtaining consistent results using the same input variables To check that the radiation output is consistent when identical exposures and condition are used Frequency of Test

• At the start of a quality control program
• Yearly
• As necessary

Equipment Required

• A water phantom, consisting of a plastic flagon or bucket filled to a depth of 10cm
• Two sheets of lead rubber

One 24 x 30cm loaded cassette

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Radiation output Reproducibility Test – obtaining consistent results using the same input variables Method

Place the cassette face up on the x-ray table Cover three quarters of the cassette with lead rubber, crosswise, leaving an end section uncovered Set a 100 cm FFD (SID)

• Collimate the beam to cover the uncovered section
• Place the water phantom over the area to be irradiated
• Set an exposure that will produce a low density of the film (80kV) and a low mAs
• Check that the mains compensator is correctly set

Make an exposure

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Radiation output Reproducibility Test – obtaining consistent results using the same input variables Repeat this procedure for each of the remaining three sections Process the film

• The same cassette should be used each time the test is carried out

Evaluation

Compare the densities. Use a densitometer, take reading from the centre of each image and compare The conditions for all four exposures were identical; therefore all densities should be the same If they are not the same the unit is not producing a consistent output Tolerance variation < 0.05

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Radiation output Reproducibility Test – obtaining consistent results using the same input variables Action

If the densities are not the same repeat the test at different times of the day. Mains fluctuations may be the problem If the densities remain inconsistent, call the x-ray engineer If the inconsistencies are minimal continue to use the unit If the inconsistencies are unacceptable, then stop using the unit until the fault has been corrected Mark all films with date and time, and keep for reference Record exposure factors, FFD, water phantom details, size of the x-ray field, cassette number and type of film used, for future reference File a report

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Constancy of Radiation output at different mA settings Test A test to check the reliability of the mA and time settings. The photographic effect for a given mAs value should remain constant even through the mA and time factors may be varied. All other factors being constant Frequency of Test

• At the start of a quality control program
• Yearly
• As necessary

Equipment Required

• A step wedge or 10cm water phantom
• Two sheets of lead rubber

One 24 x 30 cm cassette

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• Constancy of Radiation output at different mA settings Test
• Method

Carry out the procedure used for the reproducibility test, with the following exceptions Use three exposures with the same kV and mAs values, but differing combinations of mA and time By varying the mAs and time factor, but retaining the same mA and kV values as before, it should be possible to identify which of the factors is at fault Suggested exposure:

• Exposure 1: 80kV 10mAs (50mA 0.2sec)
• Exposure 2: 80kV 10mAs (100mA 0.1 sec)

Exposure 3: 80kV 10mAs (200mA 0.05sec)

Quality Assurance and Quality Control IN DIAGNOSTIC RADIOGRAPHY

• Constancy of Radiation output at different mA settings Test

Evaluation

Despite the fact that the mA and time vary, the mAs value remains the same, as does the kV, therefore all film densities should be the same If the densities are not the same, then it must be assumed that one or more of the exposure factors are inaccurate or inconsistent Action

• If the densities remain inconsistent, call the x-ray engineer
• If the inconsistencies are minimal continue to use the unit
• If the inconsistencies are large, stop using the unit until the fault has been corrected

Mark all films with date and time, and keep for reference Record exposure factors, FFD, water phantom details, size of the x-ray field, cassette number and type of film used File a report

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Control Panel Check

• Frequency of check
• Yearly
• As necessary
• Equipment required
• Control panel to be checked
• Method
• Check that all meters are working, and all illuminated panels are lit
• Check that all read outs are visible and are accurate

Check that all signage is readable and correct

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Control Panel Check

• Method

Check that hand switch operates effectively and is not damaged Check that the cable to any extension hand or foot switch is not damaged or showing signs of wear and that the electrical connections are secure Action

• Correct any simple faults
• For more complicated faults call an x-ray engineer
• Inform staff

File a report

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• X-ray Tube and High Voltage Cables check frequency of check
• Frequency of check
• Yearly
• As necessary
• Equipment required
• Equipment to be checked

Methods

Check that the tube is securely fixed to its support and that any movement locked are working effectively Check that the collimator is securely fixed to the tube and that it rotates freely

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• X-ray Tube and High Voltage Cables check frequency of check
• Inspect the high tension (HT) cables

Check for damage, wear or acute bending Check that any cable support brackets are firmly fixed and that the cables lie in them correctly Check that the cables hang freely, do not catch on anything and extend to their required limits without unnecessary tension Evaluation

Anything that is damaged, considered unsafe or has potential for wear or damage should be corrected as soon as possible

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• X-ray Tube and High Voltage Cables check frequency of check
• Action
• Correct any simple faults immediately
• For more complicated faults, call an x-ray engineer
• Inform staff

File a report

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• X-ray tube, column, table and upright bucky
• (Locks and Movements check)
• Frequency of check
• Yearly
• As necessary
• Equipment required
• Equipment to be checked
• Method

Test all movement locks for effectiveness and ease of use Test the freedom of movement of the column along the floor and if it travels the full length of the track Any ceiling tracks should be tested in the same way Look for any wear or damage

Check for loose or missing screws, bolts or fittings

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• X-ray tube, column, table and upright bucky
• (Locks and Movements check)
• Action
• Correct any simple faults immediately
• For more complex faults, call an x-ray engineer
• Notify staff

File report

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Alignment of –ray beam to table test The x-ray beam must be perpendicular to the tabletop, when in the normal over – couch position. Most x-ray tube mountings allow limited angling across the table. The lock for this movement sometimes slips or is difficult to adjust accurately. This test can also be applied to the upright Bucky Frequency of test

• Yearly
• As necessary
• Equipment required

Equipment to be tested

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• Alignment of –ray beam to table test

Method

First check the alignment of the light field and x-ray field in the collimator. If an error is found this must be corrected before starting further tests Ensure that the tube is perfectly straight Switch on the collimator light

Lower the tube until the window of the collimator is just above the table top Adjust the tube until the centre line of the light field is on the centre line of the table

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• Alignment of –ray beam to table test

Evaluation

If the centre line of the light field does not remain on the centre line of the table during tube movement, there is an alignment problem.

If the centering notch cannot be located when the tube is correctly centred to the table, there is an alignment problem. The possible causes are :

• The x-ray tube has slipped in its mounting
• The tube column is not vertical
• The cross arm (if there is one) is not horizontal
• The tube column track is not parallel to the table
• The table is not level
• The centering notch is wrongly located
• The tube column track is the wrong distance from the table

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• Cleanliness of Equipment
• Methods

Wipe over all equipment surface using a dry cloth If dirt / marks on non electrical equipment cannot be removed dampen the cloth slightly with water Action

• Keep records of daily cleaning routines
• Record condition of equipment

POTTER BUCKY

Mounted under an x-ray table, or in upright form, it consists of a cassette tray, above which is mounted grid, which move during the exposure . Provides the benefits of a grid, but with the movement diffusing out the image of the gridlines

Quality Assurance and Quality Control IN DIAGNOSTIC RADIOGRAPHY

• Cleanliness of Equipment
• Operation test
• Frequency of test
• Yearly
• As necessary
• Equipment required
• Potter – Bucky to be tested
• Method
• Check bucky movement on mounting rails
• Check efficiency of locks
• Check bucky tray movement and cassette clamp

Check that grid movement takes place during exposure N/B during the test close the collimator shutters and direct the x-ray beam well away from the person carrying out the check

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• Cleanliness of Equipment
• Action
• If bucky does not run freely on rails
• Look for obstruction and free it
• Lubricate rails
• Request replacements if appropriate
• If locks are faulty
• Adjust or request replacement
• If bucky tray movement is faulty
• Look for obstruction
• Lubricate

Quality Assurance and Quality Control IN DIAGNOSTIC RADIOGRAPHY

• Cleanliness of Equipment
• Action
• If cassette clamp is faulty
• Adjust and / or lubricate
• Repair or request replacement
• If grid movement appears to be erratic, carry out grid movement test
• If it not possible to fix the problem call an x-ray engineer

File report

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Grid movement test

The grid is a potter bucky is designed to move from slide to side during the exposure, when switched on. Movement may be too fast, too slow, erratic or not take place at all Frequency of test

• Yearly
• As necessary
• Equipment required
• Bucky to be tested

One 34 x 43 cm loaded cassette

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• Grid movement test
• Method
• Place the cassette, faceup, in the bucky tray and push the tray in
• Set a 100cm FFD (SID)
• Centre the x-ray beam to the bucky and collimate to cover the film
• Set am exposure to give a density of 1(approximately 55kV 20mAs ).
• Switch the bucky on
• Make an exposure

Process the film

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• Grid movement test

Evaluation

If there is an even, clear pattern of grid lines over the whole of the film the grid did not move at all, or moved too slowly, or for only part the exposure If there is uneven pattern of grid lines over the film the grid moved erratically If the grid lines could not be seen, the grid moved, as it should Action

• Check to see if anything is stopping the grid movement
• Check the cable and electrical connections
• Re set
• If you have been unsuccessful call an x-ray engineer
• Inform staff

File a report

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Portable and mobile x-ray units

Portable x-ray unit is defined as a small x-ray unit capable of being dismantled and carried from one location to another. It is relatively simple in design, has a maximum kV of about 80 -90, a maximum mA of about 30 – 50,a clockwise timer and a stationary anode tube. Uses a 240 –volt power supply Moving the unit

• Switch off and remove the plug from the power supply
• Coil the cable
• Unplug the component parts and coil cables
• Dismantle tube stand
• The unit may be carried
• Take care that you do not drop any parts

Do not carry too much at the same time

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• Portable and mobile x-ray units
• Setting up the unit
• Place the component parts close enough for the cables to reach
• Fit plugs firmly into correct sockets
• Assemble tube stand if necessary

Plug in to a 240 – volt power supply

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• Portable and mobile x-ray units

Mobile

Mobile x-ray unit is defined as an x-ray unit on wheels, capable of being moved from one location to another with relative ease.

It is bigger than the portable, has a higher output and is usually a little more sophisticated. May or may not have a stationary anode tube. Has an electronic timer. The maximum kV is about 90 -100 maximum mA about 50 to 100. may have a pulsed output or capacitor discharge. Uses a 240 volt power supply.

More sophisticated mobile units may be medium or high frequency and may have driven movement

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• Portable and mobile x-ray units

Moving the unit

Mobile units which need to be pushed, have brakes which operate on the “dead man’s handle’’ principle. The break handle must be depressed to release the brake. Letting go of the brake handle put the brake on Units which are motor driven, have a lever or button which operates the motor. When released the motor stops and the brakes are applied Before moving the unit, make sure that the tube arm is in the correct ‘park ‘ position and firmly locked in place Remove the power cable plug from the power socket and store in the correct location on the unit

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• Portable and mobile x-ray units

Mobile

Coil the cable neatly and systematically, ensuring that it does not twist and will not tangle when uncoiled If the hand switch is on a cable, make sure that the cable is stowed away so that it will not catch in the wheels or passing objects When pushing the unit ensure that you do not run into anything or any person Take care when passing over uneven ground Take care when going up and down a slope

Quality Assurance and Quality Control IN DIAGNOSTIC RADIOGRAPHY

• Portable and mobile x-ray units
• Checking the x-ray output
• Routine maintenance
• Mechanical
• Check all locks – Check brakes
• Check tube arm movements – Check collimator
• Electrical
• HT cables for wear and abnormal bends
• Hand switch cable fro wear, if fitted
• Power supply cable for wear and twisting
• Plugs and connections
• All control panel display lights are working
• All switches are tight and working
• Meters working
• Unit exposes when exposure button depressed

N/B Any fault must be fixed or reported immediately

Quality Assurance and Quality Control IN DIAGNOSTIC RADIOGRAPHY

• Portable and mobile x-ray units
• Checking the x-ray output
• Cleaning

Dust daily with a clean dry cloth

Dirt that resists a dry cloth should be wiped with a cloth very lightly dampened with water