Fiducial Markers for Radiation Therapy
Fiducial markers are small metal objects about the size of a grain of rice. Your radiation therapist uses them to find the tumor and treatment area when setting you up for treatment. This makes sure the radiation is delivered to the tumor instead of the nearby healthy tissue. Fiducial markers may be helpful for lining up these parts of your body:
- Lung or chest wall.
- Liver, gallbladder, kidney, or pancreas.
- Head & neck.
The fiducial markers are placed into the soft tissue. They are placed several days before you start your radiation therapy. They will stay in the soft tissue forever. Fiducial markers are used along with your tattoos to get you in the best position possible for treatment.
How should you prepare for fiducial marker placement?
When prepping to have your fiducial markers placed you will be asked to do a few things. They may include:
- Stopping certain medications. Examples: Aspirin, ibuprofen, steroids, vitamin E, or blood thinners. Make sure your provider is aware of all medications and supplements you are taking.
- Doing an enema to clean out your bowels the morning of your procedure.
- On the day of your procedure, you may need to take an antibiotic to prevent infection.
- You can usually eat and drink like normal on the day of your procedure.
The prep needed depends on where your fiducials markers are being placed. Your provider will talk to you about the specific prep you need to do.
What can you expect on the day of your procedure?
You will be asked to lie on a table and a nurse will watch your heart rate, blood pressure, oxygen levels, and pulse. In some cases, you may get an intravenous line (IV) for medication that will make you sleepy, medication to make you relax, or antibiotics (medicine that fights bacteria) before your procedure. They may also use a numbing lubricant or shot to numb and lessen any pain during the procedure. This will all depend on where the fiducial markers are being placed.
The placement of the fiducial markers is often guided by either computed tomography (CT scan) or ultrasound (US). In some cases, an endoscope, a flexible device with a light that is used to see inside a body cavity or organ, is also used. The type of imaging used depends on the type and place of the tumor.
The fiducial markers are put into place using a tool that looks like a needle. The needles are placed through the skin and into the tumor. You may feel pressure when the needles are being placed. The markers are in the needle and are pushed into place using image guidance (CT or US). After each marker has been put into place the needle is removed.
At least three fiducial markers will be placed and your healthcare provider will let you know how many markers you will have. The number of markers used depends on the type and place of the tumor. The fiducial markers are often placed in different areas of the tumor. This helps the therapists position you correctly using the markers.
A small bandage or band-aid will be used where the needles were put in. It takes about an hour and the procedure is often done as an outpatient so you will go home that day. You will need to have someone drive you home.
What can you expect after the procedure?
After the procedure, it is normal to be sore for a few days in the area where the needles were put in. If you are having pain that is not managed, call your provider. In most cases, you can remove the bandage the next day and shower or bathe like normal.
Reasons to call your care team:
- A fever (temperature > 101°F).
- Feeling dizzy.
- Heavy bleeding.
- Trouble passing urine.
- Bright red blood clots in your urine.
Fiducial placement may be specific to the center where you are having the procedure done. If you have any questions, make sure to talk to your provider.
Kengo Ohta, Hiroyuki Ogino, Hiromitsu Iwata, Shingo Hashimoto, Yukiko Hattori, Koichiro Nakajima, Maho Yamada, Masashi Shimohira, Jun-etsu Mizoe, Yuta Shibamoto, Feasibility of transrectal and transperineal fiducial marker placement for prostate cancer before proton therapy, Japanese Journal of Clinical Oncology, Volume 51, Issue 2, February 2021, Pages 258–263, https://doi.org/10.1093/jjco/hyaa172
Kerdsirichairat, Tossapola; Shin, Eun Jib Role of endoscopic ultrasonography guided fiducial marker placement in gastrointestinal cancer, Current Opinion in Gastroenterology: September 2020 - Volume 36 - Issue 5 - p 402-408 doi: 10.1097/MOG.0000000000000662