Ask Annie

I hope everyone has survived the holidays and is comfortably back at work full and happy! Remember...Valentines Day is just around the corner so make some room for chocolate!

This month's techtalk is an "ASK ANNIE". Always popular to hear from our colleagues. I love it. It never fails to prove how clever, innovative and wonderful we really are. Enjoy!

Dear Annie,

What is the correct KVp. to use for mammography?

Sincerely,

L.B. Norfolk, VA

Dear L.B.,

First, let me make it absolutely clear that I am no service engineer or certainly not a medical physicist. Your K.V. should be fixed firmly within government guidelines, tested at least twice a year and calibrated correctly by the required professional personnel.

The working mammographer however has some control over her exposure values and in that context I can offer some broad guidelines about K.V.

Roughly, the lower the K.V. value used to create the x-ray beam, the higher the image contrast will be. A high contrast picture is not much good to us if the energy or oomph of the beam is not adequate to penetrate the subject we are trying to image. For adequate penetration and a reasonable contrast in modern mammography KVp’s of between 25 and 28 are generally used. The trick, of course, is to choose a K.V. in this range that will give you maximum contrast and still penetrate your subject matter.

Lowering the K.V. to lower than 25 raises the MGD dramatically and is unable to penetrate most breast tissue adequately. An obvious exception to this of course is specimen radiography where dose and penetration are simply not factors.

Raising your K.V. above 28 can result in serious degradation of your image contrast. This can result in a large percentage of missed abnormalities. There are, of course, a few exceptions to this rule of thumb also, although very few. Some examples are:

• You may have to raise your K.V. a couple of steps when attempting to penetrate free injection of silicon into the breast tissues
• It may be necessary to raise your K.V. in order to lower your time sufficiently to freeze subject blur in a patient who is shaking badly
• It may be necessary to penetrate recently radiated tissue
• It may be necessary to raise your K.V. slightly to penetrate an unusual involution of fluid either from lactation, lymphedema or wide spread disease

These suggestions should be regarded as a very general guideline and any major change or adjustment to any of your exposure factors should be implemented solely by your medical physicist.

Hope this helps,

Annie

Dear Annie,

What exactly should I expect my breast compression to do and should my patients feel pain?

C.C. Los Angeles, Ca.

Dear C.C.,

The compression applied to the breast during mammography should be used to accomplish several tasks. The compression should immobilize the pectoral grid and breast mound and freeze your positioning in place. It should spread the breast parenchyma out smoothly over the image surface and it should even out the natural pyramid shape of the breast to reduce its’ thickness.

The premise behind reduction of breast thickness by compressing the natural triangle breast shape is to spread the tissue out to demonstrate hidden lesions and to reduce the MGD by making the subject smaller. The idea is not to crush every breast down to the average 4cm. If the compression is applied parallel to and directly posterior to the pectoral grid and if the compression paddle is used to immobilize the projection and not as a positioning tool; it should not be necessary to cross the line from discomfort to real pain. The breast should be compressed until taut, not blue, not white; just taut to the touch. If the tolerance of the patient does not allow it, apply as much to ensure that motion blur does not compromise the image.

If your patient is completely non compliant, rather than taking useless image after useless image, consult the radiologist for an alternative imaging solution.

Compression is not always objective, take clues from your patient,

Annie

Dear Annie,

Is there an easy method for testing my compression device? This test has fallen to me now that it is required quarterly. What equipment do I need and what am I looking for?

Yours Truly,

N.W. Raleigh, N.C

Dear N.W.,

Your compression device should be tested quarterly or every three months. It must be tested in both manual and automatic power mode for adequate compression weight and for proper automatic release.

The equipment used for this test is economical and easy to come by. You will need an ordinary, flat top, analog bathroom scale and a few thick terrycloth towels.

Method:

1. Place a towel on the cassette holder and then place the scale (dial side up) directly under the paddle.
2. Place a folded towel on top of the scale (leaving the dial visible). Using the power drive allow it to operate until it stops automatically.
3. Read and record the maximum compression achieved and then release device.
4. Using the manual device move the paddle down until it pushes back on its’ own.
5. Read and record the maximum compression achieved and then release the device.

Acceptable compression force is between 30 - 40 lb. (16 - 25 Kg.). This should be about the same in both power and manual modes. If the required performance criteria are not met contact your service engineer to make the appropriate adjustments.

Note: DO NOT allow your compression device exceed 45 lb. This could damage the device. If your automatic release is malfunctioning in this manner, release the device and contact service immediately.

Making sure your compression device is compliant is a legal issue; take care with it,

Annie

Dear Annie,

When checking and charting our cases, our radiologist would like us to point out any unusual or questionable areas we notice in our images. However, the technologist’s comments are always filed with the patient’s chart, so, we must be careful not to diagnose, suggest follow-up or comment on treatment or prognosis. Anne, do you have any suggestions as to making concise, clear, descriptive technical notation?

Thanks in advance,

A.S. Don Mills, Ont.

Dear A.S.,

Great question!! As our specialty gets more scientifically diverse and we need to be more and more technically apt many of our training programs no longer have time to emphasize patient care, medical charting or communication. Sometimes I think old-fashioned concise professional charting is becoming a lost art.

When making an entry in a patient’s medical file always, date your entry, sign your entry, and do not leave room on either end of your entry for unauthorized editing. Remember you are asking about a questionable area not diagnosing a disease, so, always start this type of an entry with a ‘?’ or the word ‘query’. Avoid diagnostic terminology such as cyst, DCIS, LCIS, carcinoma, fibroadenoma, etc. Instead is more to describe what you see according to standard criteria.

Best-Practice Description of Abnormalities in Chart

Visible masses:

Describe as to

• Shape= round, oval, lobulated, well defined\ill defined, stellate, ragged.
• Size and location= in mm at largest point, in what ‘hour of the clock’ and how many cm from nipple base.
• Border= smooth, hallowed, encapsulated\infiltrating, irregular, incomplete
• Density= radiolucent, low density radiopaque (= to parenchyma), high density radiopaque (>parenchyma), radiolucent\opaque combination
• Surrounding tissue= displaced, infiltrated, retracted

Calcifications:

Describe as to

• Form - rounded\irregular
• Size - uniform\varied
• Density - uniform\varied
• Distribution - scattered, Uni\bilateral, clustered, ductal
• Margins - smooth, chunky, well defined\irregular, incomplete, ill defined
• Number - few, separate, easily counted\many, crowded, not easily counted
• In relation to mass - inside, outside, peripheral

Breast Discharge:

Describe as to

• Uni\Bilateral
• Colour
• Clarity
• Spontaneous\expressed

Asymmetry:

Describe as to:

• Shape
• Density
• Size
• Location

THE EINSTEIN IDEA CORNER:

1. Since, unfortunately, lung cancer is edging out breast cancer as a killer of women; our facility has been handing out ‘Stop Smoking and Save our Women’ buttons with each mammogram.

B.L. in Riverside, Ca

2. We have a lot of handicapped, paraplegic and wheelchair bound patients, so, naturally we have some unique mobility and positioning problems. Our department purchased a high quality drafting chair and our handy manager attached an old fashioned, wide, lap type car seat belt to it. We can now quite easily transfer our chair bound clients to this seat, secure them safely and then move them at will within the room or department. This chair is fully adjustable, has a comfortable and secure contour seat, an adjustable foot rest and can be completely immobilized with sandbags. This has been an easy, economical solution to some very difficult positioning problems.

W.L. Rochester, N.Y

3. Instead of masking our mammoviewer with black paper, we have been using exposed, developed x-ray film cut to size for this job. It produces a nice natural ambient background environment and the light coming through the masking is identical to the light coming through the exposed part of our mammograms. This is very effective for increased perception and much easier on the eyes.

M.P. Durham, N.C

4. Now that the A.A.R.T. and the A.C.R. demand higher CME hours to retain our specialty certification in mammography and because, at this facility, we believe continuing education should be a joint responsibility we have set up a CME lottery. All the certified mammography techs in this department put $5.00 a month into the education fund. Every 6 months one tech is chosen to apply for a worth while course, lecture or workshop. After taking the workshop she will present a short synopsis of the information to the rest of the department so we won’t miss out on the new info. Our management matches the fund dollar for dollar and in this way our whole team retains their certification and everyone benefits from the resulting increased technical knowledge.

C.A. Princeton, N.J

Thank you all for your brilliant suggestions. Wow!! What a creative, innovative group we are.

SUMMARY:

Keep the questions and suggestions coming in, I love hearing from you and we can all learn from each other!