What is Proton Therapy
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What are Fiducial Markers and why do they matter?

What are Fiducial Markers and why do they matter?

Smaller than a grain of rice, fiducial markers are tiny metal objects that are implanted inside the body to act as a “radiologic landmark,” pinpointing the tumor’s exact location with greater accuracy and precision. For most tumors, three to six markers are inserted, which allows those performing the treatment to deliver the maximum radiation dose while sparing healthy tissue simultaneously.

Fiducial markers look different depending on the type of cancer being treated, and must be securely placed near the targeted tumor to ensure that they do no migrate during treatment. For ocular patients, tantalum clips are used that can be seen under radiographic imaging, whereas those with prostate cancer typically use gold, minimally invasive markers. Implanting fiducial markers is done prior to starting radiation therapy and takes less than 15 minutes. Once the treatment is completed, the markers continue to remain in the body.

In relation to proton beam therapy, fiducial markers play an important role in delivering proton radiation to the tumor. Fiducial markers are inserted into the body through a thin needle, creating a reference point that can be used to accurately align the patient’s tumor with the beam that delivers proton therapy. Additionally, they also help minimize the risk of both short and long-term side effects and spare healthy surrounding tissue from radiation, such as the heart and lungs.