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Citation:
900.12(b)(8)(ii)(A)(B)(C)(D)(E): Compression Paddle.
(A) Systems shall be equipped with different sized compression paddles that match the sizes of all full-field image receptors provided for the system. Compression paddles for special purposes, including those smaller than the full size of the image receptor (for "spot compression") may be provided. Such compression paddles for special purposes are not subject to the requirements of paragraphs (b)(8)(ii)(D) and (b)(8)(ii)(E) of this section.
(B) Except as provided in paragraph (b)(8)(ii)(C) of this section, the compression paddle shall be flat and parallel to the breast support table and shall not deflect from parallel by more than 1.0 cm at any point on the surface of the compression paddle when compression is applied.
(C) Equipment intended by the manufacturer’s design to not be flat and parallel to the breast support table during compression shall meet the manufacturer’s design specifications and maintenance requirements.
(D) The chest wall edge of the compression paddle shall be straight and parallel to the edge of the image receptor.
(E) The chest wall edge may be bent upward to allow for patient comfort but shall not appear on the image.
Discussion:
No, to both questions. A facility must have on hand at least one cassette-grid-compression paddle combination of each of the 18 x 24 cm and 24 x 30 cm sizes to equip each mammography x-ray unit in the facility. "Spot compression" paddles are not required.
No. The requirement for the paddle to be parallel is only applicable when compression is applied. Once the diagnostic range of compression is reached the paddle should be parallel to the support table and not deflect from parallel by more than 1.0 cm when compression is applied.
No to both questions. First, if the system was designed to have the plate remain flat and parallel, then the situation you describe would not meet the intent of the regulation and the worn part(s) must be repaired or replaced. Second, the regulations do not currently cover interventional procedures so accessory devices used solely for such procedures, even when they are used on accredited units, are not required to meet the regulations.
Conventional paddles are designed to provide essentially flat compression across the breast to yield a uniform thickness of tissue for the mammographic study. However, some systems incorporate paddles designed to provide uniform compression pressure rather than thickness. Such systems must continue to operate consistent with their design over the life of the unit. This requirement simply states that the facility must maintain the system to the manufacturers' specifications.
Yes. The intent of the regulation is that the chest wall edge be generally straight as opposed to curved to fit the general chest wall shape. Some older paddles/compression cones were formed to a curved shape at the chest wall edge and this section was included to prevent their use.
No. 900.12(b)(8)(ii)(E) is only applicable to full sized compression paddles when used with their matching image receptors.
When the mammography unit is initially placed in service or if the entire compression system is replaced, the medical physicist must perform the compression paddle deflection test as part of the mammography equipment evaluation. This test should also be performed periodically throughout the life of the unit or when an old full field compression paddle is replaced with a new one. Periodic testing and testing of a new full field compression paddle may be done by a radiologic technologist or other qualified person but should be performed in consultation with the medical physicist. The frequency of periodic testing should be established with reference to the manufacturer’s maintenance-specifications and the use considerations (wear and tear) unique to the facility. If the excessive deflection of the compression paddle is identified during a mammography equipment evaluation, it must be repaired before the paddle is used on patients. If the facility identifies the problem at any other time, it should be repaired as soon as possible because this problem may compromise clinical image quality. Manufacturers may specify procedures and frequency for testing the compression paddles in their maintenance instructions and adherence to these recommendations should normally be adequate; however the responsibility for compliance still remains with the facility.
One acceptable method for performing the compression paddle deflection test is:
1. If the mammographic unit does not have a read-out of compression force, cover the bucky with a towel and place a bathroom scale on the towel.
2. In order to prevent measuring deflection of the image receptor support (bucky) or the scale, place a support plate on top of the scale or directly on the towel if a scale is not used. The support plate should be made of a rigid material (e.g., acrylic sheet) that is large enough to completely cover either the scale or bucky.
3. Place the test object on the support plate with its base along the chest wall edge of the compression plate. Examples of test objects include: compressible foam materials (e.g. T-200 Minicel foam (10 X 18 cm for the 18 X 24 cm paddle and 14 X 22 cm for the 24 X 30 cm paddle, thickness of 4 to 6 cm) or tennis or rubber balls taped together in the shape of an equilateral triangle (3 balls for the 18 X 24 cm paddle and 6 balls for the 24 X 30 cm paddle)
4. Apply a compression force of 111 newtons (25 pounds).
5. Measure the distance of each corner of the paddle from the support plate.
6. Subtract the smallest distance from the largest distance to determine the deflection. The difference must be 1.0 cm or less to pass the test.
Paddles designed not to be flat and parallel to the breast support table during compression should not be evaluated using the procedure described above, but rather must meet the manufacturer’s design specifications and maintenance requirements.
No. Section 900.12(b)(8)(ii)(A) specifies that the system must have different paddles matched to each image receptor size provided.
Acceptable documentation would include letters from the manufacturer, copies of manuals provided by the manufacturer, user instructions, or similar manufacturer-provided materials that indicate the design intent of the paddle.
The intent of this regulation is to prevent the use of paddles with a significant concave shape to the central portion of the chest wall edge of the paddle. These types of paddles have been found to provide inadequate imaging of chest wall breast tissue.
The edge of the straight paddle does not have to be perfectly straight, but rather, it is required that the manufacturer intended it to be straight and that it be made as straight as manufacturing processes allow. For example, if an original or third party manufacturer offers a paddle with a curved chest wall edge in addition to their straight edge paddle, then the curved paddle would not meet the requirement. As an aid in determining the adequacy of a particular design, the user may consult the manufacturer.
For each x-ray unit, the facility must have at least one standard full-sized compression paddle for both required image receptor sizes. These paddles must have a straight chest wall edge. Special purpose paddles may be provided as needed. Under the regulations, compression paddles that are designed for special purposes are exempt from the requirement that the chest wall edge of the paddle be straight and parallel to the edge of the image receptor. Special purpose paddles are those not routinely used to produce the standard MLO and CC mammographic views.
Related Topics:
Semiannual Equipment Quality Control Tests
Decompression Annual Quality Control Test