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Basic quality control tests in medical radiography. Finals Topics. -DARKROOM QUALITY CONTROL -QUALITY CONTROL FOR X-RAY EQUIPMENT AND ACCESSORIES. Films Determination of the Optimum Developing Time Check for the consistency of the generator output Check for mAs linearity

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darkroom quality control

Films

  • Determination of the Optimum Developing Time
  • Check for the consistency of the generator output
  • Check for mAs linearity
  • Check for Timer Accuracy
DARKROOM QUALITY CONTROL
quality control for x ray equipment and accessories

Collimator Check

  • Check for Alignment of the X-ray Tube Column and the X-ray Table
  • Test for Grids
  • Test for Bucky Movement
  • Test for Lead Rubber Aprons and Gloves
QUALITY CONTROL FOR X-RAY EQUIPMENT AND ACCESSORIES
darkroom qc

FILMS

  • Checking for:

- Expiry date

* “FIFO” method should be observed

- Storage conditions

* temperature at about 20-25 C

* away from sources of heat and where chemical vapors may

leak and fog the film

* boxes of films should not be stored on the floor; should be

stacked vertically to avoid pressure marks

DARKROOM QC
darkroom qc1

DETERMINATION OF THE OPTIMUM DEVELOPING TIME

  • Objective

- To determine the developing time that will give the film’s maximum density without an increase in base + fog.

  • Procedure

- Expose the loaded cassette in strips (6 strips) using the lowest kVp and mAs setting at 100cm SID. The exposure factors may be adjusted until we are able to produce a density of 1.0 on the middle strip. The last strip is not exposed to radiation.

DARKROOM QC
slide7

PRODUCTION OF SENSITOMETRIC STRIPS

X-ray film Lead sheet

Cut into a number of strips

darkroom qc2

DETERMINATION OF THE OPTIMUM DEVELOPING TIME

  • Procedure

- Inside the darkroom, cut the film into strips and process them using different developing times, e.g. 30s, 60s, 90s, 120s, 150s & 180s.

DARKROOM QC
slide9

DARKROOM QC

DETERMINATION OF THE OPTIMUM DEVELOPING TIME

Evaluation

- Examine the film strips, look at the middle step and determine which

strip exhibit the maximum density at an acceptable basic fog. The time

used to develop this strip is considered the optimum developing time.

qc for x ray equipment and accessories

CHECK FOR THE CONSISTENCY OF THE GENERATOR OUTPUT

  • Objective

- To determine whether the generator produces the same density every time the same exposure factors are selected.

  • Procedure

- Position the water phantom on the loaded cassette and expose the film with set factors. Process the film the usual way.

QC FOR X-RAY EQUIPMENT AND ACCESSORIES
qc for x ray equipment and accessories1

CHECK FOR THE CONSISTENCY OF THE GENERATOR OUTPUT

10cm H2O

10cm H2O

10cm H2O

10cm H2O

QC FOR X-RAY EQUIPMENT AND ACCESSORIES

Exposure 1

Exposure 2

Exposure 1

Exposure 2

A. Consistent generator output

B. Inconsistent generator output

qc for x ray equipment and accessories2

CHECK FOR mAs LINEARITY

  • Objective

- To determine any differences in photographic density when different mA settings are used for equal mAs value.

  • Procedure

- Position the water phantom on the loaded cassette and expose the film with set factors. Process the film the usual way.

QC FOR X-RAY EQUIPMENT AND ACCESSORIES
qc for x ray equipment and accessories3

CHECK FOR mAs LINEARITY

Good

Linearity

10cm H2O

10cm H2O

10cm H2O

QC FOR X-RAY EQUIPMENT AND ACCESSORIES

Exposure 1

50mA & 0.2s

Exposure 2

100mA & 0.1s

Exposure 3

200mA & 0.05s

qc for x ray equipment and accessories4

CHECK FOR mAs LINEARITY

Poor

Linearity

10cm H2O

10cm H2O

10cm H2O

QC FOR X-RAY EQUIPMENT AND ACCESSORIES

Exposure 1

50mA & 0.2s

Exposure 2

100mA & 0.1s

Exposure 3

200mA & 0.05s

qc for x ray equipment and accessories5

CHECK FOR TIMER ACCURACY

  • Objective

- To determine the accuracy of the x-ray timer.

  • Procedure

- Position the spinning top on the loaded cassette and expose the film using the clinically used exposure times. Process the film the usual way.

QC FOR X-RAY EQUIPMENT AND ACCESSORIES
qc for x ray equipment and accessories7

CHECK FOR TIMER ACCURACY

For mains supply with 60Hz frequency:

One-pulse (self rectified) unit

Set time (sec) No. of dots

0.05 3

0.10 6

0.50 30

1.00 60

Two-pulse (full wave rectified) unit

Set time (sec) No. of dots

0.05 6

0.10 12

0.50 60

1.00 120

QC FOR X-RAY EQUIPMENT AND ACCESSORIES
qc for x ray equipment and accessories8

COLLIMATOR CHECK

  • Objective

- To check if the radiation field is the same as the area

illuminated by the light from the collimator.

  • Procedure

- Center the loaded cassette in the useful beam at a commonly used SID. Collimate the field to approximately half the film’s size and place a metal marker at the center of the illuminated area and mark the inside edges with lead wires. Make an exposure using appropriate technique factors. Make a second exposure with the collimator fully opened. Process the film the usual way.

QC FOR X-RAY EQUIPMENT AND ACCESSORIES
qc for x ray equipment and accessories10

COLLIMATOR CHECK

Radiation field

Light field

QC FOR X-RAY EQUIPMENT AND ACCESSORIES

The misalignment should not exceed 2% of the SID

qc for x ray equipment and accessories12

CHECK FOR THE ALIGNMENT OF THE X-RAY TUBE COLUMN AND THE X-RAY TABLE

  • Check whether the column is vertical
  • - Using a plumb bob, hold the string’s end against the tube
  • column making sure that the string hangs unobstructed. If
  • the column is parallel to the string, the column is vertical.
  • Check whether the table top is horizontal
  • - Place a bowl of water on top of the table at different
  • locations and measure the depth of water around the edge of
  • the bowl. If the table is horizontal, the depth of the water
  • will not vary across the bowl.
  • Check whether the horizontal arm is still horizontal
  • - Measure the distance between the cross-arm and the table
  • top in front of the cross-arm and from the back. The arm is
  • horizontal if the distance is the same from both ends.
QC FOR X-RAY EQUIPMENT AND ACCESSORIES
qc for x ray equipment and accessories13

TEST FOR GRIDS

  • Objective

- To check whether the grid gives a uniform density over its

area.

  • Procedure

- Place the loaded cassette on the cassette tray or under the loose stationary grid. Place metal markers on the cassette to indicate the position of the grid on the film. Expose the film using the recommended SID and process the film the usual way.

QC FOR X-RAY EQUIPMENT AND ACCESSORIES
qc for x ray equipment and accessories14

TEST FOR BUCKY MOVEMENT

  • Objective

- To check whether the grid bucky is moving throughout the

whole exposure.

  • Procedure

- Place the loaded cassette on the cassette tray. Place metal markers on the cassette to indicate the position of the grid on the film. Expose the film in the bucky mode and process the film the usual way. Check for presence of grid lines on the radiograph.

QC FOR X-RAY EQUIPMENT AND ACCESSORIES
qc for x ray equipment and accessories15

LEAD RUBBER APRONS AND GLOVES

  • Care

-clean with soap and water, weekly or as necessary

-should not be stored near a heat source

-aprons should be hung up using hangers; should not be fold

-gloves should be stored flat or upright on a custom holder

  • Checking for damage

-to surface covering, seams and fasteners of aprons (if any)

-check for flexibility, feeling for cracks

QC FOR X-RAY EQUIPMENT AND ACCESSORIES
qc for x ray equipment and accessories16

LEAD RUBBER APRONS AND GLOVES

  • Test to detect cracks on aprons and gloves

Method

-place the apron or gloves to be tested on the table top

-use fluoroscopy system to examine the whole article

*if radiography is to be used, placed cassettes under test articles

and make separate exposures, ensuring that the whole article is

examined

  • Evaluation

-Look for cracks or other abnormal variations of density in the

image

QC FOR X-RAY EQUIPMENT AND ACCESSORIES