Babeh Edi

Quality Control of CR Imaging Plates

E. Samei, Ph.D.

samei@duke.edu

Version 1.4, Jan. 25, 1999

The quality control of CR imaging plates requires an x-ray source, a display device (soft- or hard-copy), and a CR reader previously evaluated for satisfactory performance. It is recommended that this procedure to be performed on all the imaging plates on a monthly basis and whenever the number of small white speck artifacts in the images obtained from an imaging plate is objectionable.  Note that too frequent cleaning of the phosphor screens or the use of non-approved cleaning solutions can discolor the phosphor.

Equipment Needed:

1. A calibrated x-ray source

2. A calibrated hard/soft-copy display

3. A CR reader and ID station

4. Screen cleaning solution (for Agfa systems, Curix screen solution) and cloth

5. Lint-free gloves for handling the screens

6. A permanent marker

7. Cleaning solution for the table (alcohol)

8. A piece of cloth (towel or sheet) for cleaning the table

Cleaning the Screens

1.      Collect and stack all the cassettes to be cleaned by the CR ID station.

2.      “Read” each cassette.  Verify that the cassette ID (the number in the upper left hand corner of the screen in the “READ” menu matches the cassette label.  If not or if the label is erased, write the cassette ID on the label area of the cassette.

3.      Open the cassette and verify that the number written on the back of the screen matches that of the cassette.  If not or if the screen number is erased, write the cassette ID on the back of the screen.

4.      Repeat the steps 1-3 for all the cassettes.

5.      Erase all the cassettes.

6.      Select a room that is free of dust, is well lighted, and has a large table area.  An x-ray room with a table-top would be ideal.

7.      Clean the table-top with a cleaning solution (alcohol) and a cloth.

8.      Put gloves on.

9.      Take the screens out of the cassettes in an orderly fashion. Put cassettes and screens next to each other to avoid mixing.  Be sure not to touch the white sensitive surface of the screen (be extra careful if you have long fingernails).

10.  Visually inspect the cassettes and the screens for physical defects. Look for chipping, discoloration, bends, and cracks in the screens.  Any defects other than dust and small chippings at the edges should be recorded in the log table (you may want to record the location of such defects in the log table.

11.  Remove the dust and small particles on the screen by gently wiping the surface with the screen cleaning cloth. 

12.  If dirt resists cleaning, wipe it off using the cloth damped with the Curix cleaning liquid using a circular or straight motion.  AVOID USING EXCESSIVE PRESSURE.  Also avoid excessive use of the cleaning solution.

13.  Let the screen dry. 

14.  Clean the inside of the cassette with the screen cleaning solution and cloth, specially the tube side.

15.  Let the cassette dry.

16.  Put the screen back into the cassette.  The screen should be thoroughly dried without any residues before insertion back into the cassette.

17.  Proceed to the next step.

Uniformity Test

1.      Set the exposure set up for cross-table exposures of the CR cassettes using 80 kVp, 5 mAs, and 180 cm source-to-image distance (SID).  Make sure the entire cassette area will be exposed.

2.      Expose each cassette.

3.      Identify the cassette in the ID station under “Uniformity Test.” (Any arbitrary Accession number may be used since the images will be evaluated on the PS5000 workstation and will not be sent to PACS.) Use the following reading parameters:

            Menu:               SYSTEM DIAGNOSIS, FLAT FIELD

            Speed Class:    200

4.      Read the cassette in the CR reader.

5.      Evaluate the image on the PS5000 Processing Workstation.  The image should be uniform without any artifacts. If the screen is not properly cleaned, some white specks can be seen. The position of such artifacts vary from screen to screen, and they should be eliminated by repeating the cleaning steps outlined above. 

6.      Any artifacts other than white specks are considered abnormal and should be recorded in the QC log. Gross nonunifomities not removable by repeated cleaning should be brought to the attention of the PACS Physicist and the tech supervisor, and the screen should be removed from circulation.

7.      Click the “INFO” icon.  Under the “Exposure Info” section that is listed in the window that opens up, read the value for the “Exposure Level(s)” and record it in the QC log sheet.

8.      Delete the Uniformity test images from the PS5000 workstation after you are finished will all the cassettes.

Some QC Precautions

·        Too frequent cleaning of the phosphor screens can discolor the phosphor.

·        The imaging plate that have not been used for more than 24 hours should be erased before use.

CR Screens QC Log

Cassette Size	Cassette No.	Date	Visual Defects	Cleaning (Ö)	Nonuni-formities	Exposure Level	Comments
14 x 17
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10 x 12
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8 x 10
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