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You must acquire a phantom image specifically for accreditation purposes. Image quality will be evaluated using the same breast phantom used for routine stereotactic breast biopsy QC.
Facilities may use either an ACR-approved Mammography Phantom or a Mini Digital Stereotactic Phantom that simulates a 4.2 cm compressed breast of average density and has a wax insert containing decreasing sizes of fibers, specks and masses. The facility must purchase a phantom directly from the manufacturer. The following phantoms have been approved by the ACR for use in the Stereotactic Breast Biopsy Accreditation Program:
Computerized Imaging Reference Systems, Inc. (CIRS)(800) 617-1177; (757) 855-2765 | Gammex, Inc. (Sun Nuclear)(800 GAMMEX-1) |
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You will need the following:
One approved accreditation phantom.
If you use a screen-film unit, barcode identification labels to be affixed to the phantom image and the Phantom Exam Data form. For more information, see our article on Preparing and Submitting Your Testing Materials: Stereotactic Breast Biopsy .
At least 2 ACR-trained medical physicist phantom image reviewers will score the image. The ACR evaluation criteria are outlined in the 1999 ACR Stereotactic Breast Biopsy Quality Control Manual. The minimum scores required to pass accreditation will depend on the type of phantom and image recording system:
Recording System | ACR Mammography Phantom | Mini Digital Stereotactic Phantom | ||||
# Fibers | # Speck Groups | # Masses | # Fibers | # Speck Groups | # Masses | |
Digital | 5.0 | 4.0 | 3.5 | 3.0 | 3.0 | 2.5 |
Screen-Film | 4.0 | 3.0 | 3.0 | 2.0 | 2.0 | 2.0 |
The average glandular dose may not exceed 300 mrad (3 mGy). Your physicist must still check AGD during the medical physicist survey, even though a dosimeter is no longer required for accreditation.
If you use a prone stereotactic breast biopsy table, you may tape the phantom to the breast support when producing the images for image quality evaluation; however, be careful not to cover the test objects with the tape.
If you use a mammography unit with an add-on stereotactic biopsy device, expose the phantom with the stereotactic biopsy device in place.
Preparing Your System for a Stereotactic Procedure
Mount the stereotactic localization device with its collimator and remove the grid if necessary.
Select the exposure mode that you typically use for obtaining scout images – either automatic exposure control (AEC) or manual.
If AEC is used, be sure the AEC detector is under the center of the phantom.
Select the kVp, mAs (for manual modes), focal spot, target and filter used for stereotactic localization of a 4.2 cm thick compressed breast of a 50% adipose and 50% glandular tissue.
Mini Digital Stereotactic Phantom Instructions
Orient the phantom as shown in Figure 1.
Take 1 image using your typical technique for a scout image (AEC or manual mode).
Record all technique factors on the Phantom Exam Data form.
Figure 1: Chest Wall Side Mini Digital Stereotactic Phantom
ACR Stereotactic Accreditation Phantom Instructions
If you can remove the biopsy collimator and compression plate or have a large enough field-of-view to image the entire insert on 1 image, you may submit 1 image, as long as the entire insert is visible.
If you have a large enough field-of-view to image the entire insert on 1 image but the needle holder appears on the image, you may submit 2 images: one with the needle holder as far to the left as possible, the other with the needle holder in the far right position.
If you cannot remove the biopsy collimator, the system is restricted to the biopsy aperture, or the system is a dedicated stereotactic breast biopsy unit with small field-of view digital detector, you must submit sufficient images (One possible example shown in Figure 2) in order to image all of the test objects. Take sufficient overlapping sections of the phantom.
Use your typical technique for a scout image (AEC or manual mode).
Record all technique factors on the Phantom Exam Data form.
Figure 2: Chest Wall Side ACR Mammography Accreditation Phantom
Preparing Your Case: Uploaded Images
Upload only processed, DICOM images for accreditation. For the Mini digital Stereotactic Phantom, upload only one image. However, if you are using the ACR Stereotactic Accreditation Phantom, you may upload up to four images in order to include the entire phantom.
Preparing Your Case: Film/Screen units
Print the image(s) as close to “true size” as possible (i.e., without magnification or minification).
Do not print the phantom images on the same film that contains the clinical images.
For screen-film, process the image(s) using the processor normally used for your stereotactic clinical images.
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