Breast Seed Localization

This information explains your breast seed localization procedure at Memorial Sloan Kettering (MSK).

Breast seed localization is a procedure in which a tiny metal seed, about the size of a small sesame seed, is placed into abnormal breast tissue. The implanted seed contains a small amount of radiation. This helps your surgeon find the area of abnormal tissue during surgery when it is too small to be seen or felt by hand. The seed will stay in your body until it is taken out during your surgery.

Your doctor will explain the procedure to you and will answer any questions you have.

The Day of Your Procedure

  • Do not put anything on your breasts, nipples, or under your arms on the day of your procedure. This includes talcum powder, deodorant, perfumes, and creams.
  • Wear a 2-piece outfit.
  • Family or friends who are with you while you are having your procedure will be taken to the waiting room.
  • Tell the radiologist performing your procedure if you are allergic to any medications.
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During Your Procedure

The procedure will take about 30 minutes. You will be awake, but the area will be numbed with medication, so it will not be painful. The procedure is done during a mammogram, while your breast is compressed. If the abnormal tissue is not seen on the mammogram, ultrasound may be used instead.

A picture of the abnormal breast tissue will be taken. When the area is numb, a needle with the seed inside of it will be inserted into your breast. Two more pictures of the breast are taken. If necessary, the position of the needle will be adjusted and more pictures will be taken.

When the needle is in the correct place, the seed will be released into the tissue and the needle will be removed. The seed will stay in your breast. Another set of pictures will be taken to show the location of the seed within the area to be biopsied. Later, your surgeon will use this picture as a map to guide your surgery.

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After Your Procedure

The items you touch, people you encounter, and clothes that you wear will not become radioactive.

People who are in close physical contact with you may be exposed to very small amounts of radiation. While there is no evidence that this exposure causes harm, there are things you can do to minimize radiation exposure to others:

  • Distance. The amount of radiation emitted from your body is very small. It decreases significantly at a distance of 1 foot from the implant site. There is almost no radiation reaching a distance of 3 feet away.
  • Time. Radiation exposure to others depends on how long you remain in close contact with them. You will not harm anyone by hugging, kissing, or shaking hands. You should avoid placing an infant, child, or young animal on your chest for any longer than 30 minutes per day for the next month (30 days) or until the seed is removed during surgery.
  • Breastfeeding. Do not breastfeed while you have the seed in your breast. You can continue to pump your milk and either discard it or you can feed it to your child. The milk will not be radioactive. You can restart breastfeeding after the seed has been removed during your surgery. 

If you have any questions, please contact the Radiation Safety Service in the Department of Medical Physics at 212-639-7391.

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