Fiducial markers are small implants placed in the prostate gland to precisely guide cancer treatment. They serve as internal guides, allowing medical professionals to accurately pinpoint the prostate’s location during therapy and ensure effective treatment delivery.
What Are Fiducial Markers?
Fiducial markers are small implants, often made of materials like gold, carbon, platinum, or titanium. They are typically about the size of a grain of rice (approximately 3 millimeters in length) and are designed to be highly visible on medical imaging, acting as clear reference points.
The prostate gland can shift its position slightly due to normal bodily functions, such as breathing or changes in the bladder and rectum. This movement makes precise targeting challenging. Markers provide stable, detectable landmarks within the prostate, enabling consistent and accurate localization during treatment.
The Placement Procedure
Before placement, patients often receive instructions like bowel preparation and antibiotics to minimize infection risk. The procedure typically uses local anesthesia, sometimes with light sedation, and is usually completed within 15 to 30 minutes.
Two primary methods exist: transrectal ultrasound (TRUS) guided and transperineal. The TRUS-guided approach uses an ultrasound probe inserted into the rectum, providing real-time images for accurate visualization of the prostate.
A fine needle is guided through the rectal wall (TRUS) or perineum (transperineal) directly into the prostate. Once positioned, three to four markers are deployed from the needle, creating a three-dimensional reference frame within the gland.
Using Markers for Radiation Therapy
After marker placement, imaging scans like CT and MRI are performed. These images, combined with the visible markers, create a detailed three-dimensional map of the prostate and surrounding structures, crucial for planning precise radiation delivery.
Before each radiation therapy session, imaging (such as X-rays or cone-beam CT) locates the markers. They guide the alignment of the radiation beam with the prostate. This daily verification accounts for subtle shifts, ensuring the radiation dose consistently targets the intended area.
This tracking enhances radiation delivery accuracy. By aligning treatment precisely to the markers, radiation oncologists deliver the prescribed dose to cancerous tissue while minimizing exposure to nearby healthy organs like the rectum and bladder. This precision maximizes effectiveness and reduces side effects.
Life After Marker Placement
Following marker placement, patients may experience mild, temporary side effects. Common sensations include slight discomfort or a minor ache in the pelvic area. A small amount of blood in urine, stool, or semen is also possible for a few days or weeks.
Patients are advised to avoid strenuous activities for a day or two. Pain relievers, such as acetaminophen, can manage discomfort. Side effects are typically brief and resolve on their own; serious complications are uncommon.
The markers are permanent and remain in the prostate after treatment. Made from inert materials, they do not react with body tissues and cause no long-term issues. Patients cannot feel them once in place, and they do not interfere with daily activities or future medical imaging, including MRI scans.