Rectal Spacers and Fiducial Markers for Prostate Radiation

By: David Grew MD MPH

"Rectal spacers and fiducial markers help make prostate radiation therapy safer and more precise."

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If you are preparing for radiation therapy for prostate cancer, your care team may recommend placing a rectal spacer, fiducial markers, or both before treatment begins.

These tools serve different purposes. A rectal spacer helps create distance between the prostate and rectum to reduce radiation exposure to the rectum. Fiducial markers help the radiation team accurately locate the prostate during treatment.

Not every patient needs both. Some patients may receive a rectal spacer only, some may receive fiducial markers only, and others may receive both. Your care team will recommend the approach that fits your treatment plan.

Where is the prostate?

The prostate is a small gland located below the bladder and in front of the rectum. It surrounds part of the urethra, the tube that carries urine out of the body, and helps produce fluid that is part of semen.

Because the rectum sits directly behind the prostate, radiation treatment must be planned carefully to treat the prostate while limiting radiation exposure to nearby healthy tissues.

What is a rectal spacer?

A rectal spacer is a soft material placed between the prostate and rectum before radiation therapy.

Its purpose is simple: by gently creating more space between the prostate and rectum, the spacer can reduce the amount of radiation reaching the rectum. This may help lower the risk of bowel side effects from treatment.

The spacer is temporary. Depending on the product used, it remains in place during the period when radiation is being delivered and is later absorbed by the body. Your care team can tell you which spacer is being used and how long it is expected to remain in place.

What are fiducial markers?

Fiducial markers are very small metal markers placed inside the prostate. They are often about the size of a grain of rice.

The prostate can shift slightly from day to day depending on changes in the bladder, rectum, and surrounding anatomy. Fiducial markers act as reference points that can be seen on imaging before or during radiation treatment.

This helps the radiation team accurately locate the prostate and line up the radiation beams before treatment is delivered. The goal is to make radiation treatment as precise as possible while limiting exposure to nearby healthy tissue.

The markers usually remain in the prostate permanently and do not cause harm.

Why might I need one, both, or neither?

Rectal spacers and fiducial markers do different jobs.

A rectal spacer is mainly used to help protect the rectum.

Fiducial markers are mainly used to help the radiation team accurately locate the prostate during treatment.

Some patients receive both. Others may need only one, and some radiation techniques may not require either. The decision depends on the type of radiation being used, how the treatment is guided, your anatomy, and your care team's approach.

How should I prepare for the procedure?

Before the procedure, your care team will review your medical history and medications.

Be sure to tell them about:

• blood thinners
• vitamins and supplements
• previous infections after prostate procedures
• medicines used for diabetes or weight loss
• any other prescription or nonprescription medicines you take

Some medications may need to be adjusted before anesthesia or the procedure. You may also receive instructions about eating, drinking, or using an enema beforehand.

Follow the instructions from your own treatment center carefully. Preparation can differ depending on the procedure, anesthesia plan, and medications you take. Following these instructions can also help prevent a procedure from needing to be delayed or rescheduled.

What happens during the procedure?

The exact process varies by treatment center, but rectal spacers and fiducial markers are commonly placed using ultrasound guidance.

If fiducial markers are part of your treatment plan, small needles are used to place the markers inside the prostate.

If you are receiving a rectal spacer, the spacer material is placed in the space between the prostate and rectum.

Some centers use anesthesia or sedation during the procedure. If anesthesia is planned, your care team will give you specific instructions about eating, drinking, medications, and arranging transportation home.

What should I expect afterward?

Most patients go home the same day.

Some temporary discomfort can occur after the procedure. You may notice mild soreness, pressure, or a feeling of fullness in the rectal or pelvic area.

Your care team will give you instructions about medications, activity, and when you can return to your normal routine. Follow those instructions rather than relying on general guidance, since recovery recommendations can differ between centers.

When should I call my healthcare provider?

Your treatment center will give you specific instructions about symptoms to watch for after the procedure.

Contact your healthcare team promptly if you develop:

• fever or chills
• increasing or severe pain
• difficulty urinating
• significant or persistent bleeding
• other symptoms that concern you

Your care team can tell you what is expected after your particular procedure and what requires medical attention.

Why these tools matter

Modern prostate radiation therapy depends on precision.

Fiducial markers can help doctors accurately locate the prostate during radiation treatment. Rectal spacers can increase the distance between the prostate and rectum, helping reduce radiation exposure to nearby healthy tissue.

For patients, the important thing to remember is that these procedures are part of preparing for radiation treatment. They do not treat the prostate cancer themselves.

Your radiation oncology team will decide whether a rectal spacer, fiducial markers, both, or neither is appropriate for your particular treatment plan.

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To learn more, watch this video we made Rectal Spacers and Fiducial Markers.

To learn more about prostate cancer, browse our dedicated prostate cancer education library for more information.

Hire PRIMR to create custom video content for your clinical trial or medical product today.

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FAQs:

Does every patient getting prostate radiation need a rectal spacer?

No. Rectal spacers can be helpful for many patients, but they are not required for every prostate radiation treatment. Whether one is recommended depends on the type of radiation, your anatomy, your medical history, and your treatment center's approach. Ask your radiation oncology team whether a spacer would provide a meaningful benefit in your case.

Are fiducial markers radioactive?

No. Fiducial markers are small metal markers used as reference points for imaging and radiation treatment. They do not deliver radiation themselves. If fiducial markers are part of your treatment plan, your care team can explain how they will be used during your radiation sessions.

Will I feel the fiducial markers after they are placed?

Usually, no. Fiducial markers are very small and remain inside the prostate after treatment. Patients generally do not feel them during normal activities. If you develop unexpected or persistent pain after placement, contact your care team.

Can a rectal spacer completely prevent bowel side effects from radiation?

No. A spacer can reduce radiation exposure to the rectum and may lower the risk of bowel side effects, but it cannot guarantee that no bowel symptoms will occur. Radiation plans involve many factors beyond the spacer itself. Talk with your radiation oncology team about your individual risk and how they plan to protect the rectum during treatment.

Do rectal spacers and fiducial markers treat prostate cancer?

No. They are tools that help doctors deliver radiation therapy more safely and accurately; they do not treat the cancer themselves. The radiation is the cancer treatment. If you are unsure how these procedures fit into your overall treatment plan, ask your care team to walk you through each step before treatment begins.