Intraprostatic fiducial markers, commonly referred to as “FMs” in the medical field are a key component in the current fight against prostate cancer, specifically in patients moving into image guided radiation therapy or ‘IGRT’.

Most frequently manufactured using metals like titanium and gold, these markers enable a physician to administer a precise and direct scan of a patient's current state. From this scan normally performed by an industry standard CT, the markers guide the photon imaging system to pick up the parts of the tumor that are infected and need to be treated. It is important to note that no less than three markers must be inserted to ensure a stable and reliable read for the scan to pick up, these will remain permanently inside the patient throughout the course of treatment. Thanks to their high density, the radio opacity of these marks is accentuated under the imaging system, allowing for clear and concise contrast between present markers and blood clots/false classifications in the area.

As new technologies advance in the field, the presence of the magnetic resonance imaging or MRI, has also undeniably shifted the course of many institutes as they work to implement the advancements in curing the disease. Providing a dominant contrast image between the soft tissues and photon-imaging, the MRI machine offers a substantially clearer delineation path to the prostate. The advantage that this provides permits physicians to rigidly lock onto the markers using both a CT and MRI scan for measurements that average 1mm in proximity to the localization of the tumor. One issue that using this dual modular system poses is the spatial differences ranging between the CT and MR imaging scans. The variance between the two resolved images can often cause more rigor than return. Rising from this concern, researchers are now working to eliminate the need for both systems in case work; proposing what they call a “MR-only” workflow which would make treatment more affordable for patients as well as reduce the amount of ionising radiation emitted through image processing.

The current state of MR-only workflow has now taken shape in many forms, not all necessarily deriving from the same point of procedure. A common form of trial that researchers have worked with first and foremost is that of a “Synthetic-CT imaging system”. Based on MR images alone, this CT scan has the ability to measure prospective dosage levels, but does not enlist the manual work that is often demanded

when localising the markers and pinpointing the cancer. Without the ability to localize the marker accurately, the CT method can lose some of its viability moving into clinical trials that a similar MR-only module might be able to circumvent. Researchers working closer with the MR version have now been able to gain an insight into some of the variables that pertain to this method. Using an MRI, the FMs will appear on the screen as void. This is because fiducial markers do not produce a nuclear magnetic resonance to be picked up by the scan. Following navigation through the area, there is a chance that markers may still be mistaken for blood clots or calcification, this result depends on the relative state of the image parameters and the original placement of the markers. To advance past a problem like this, it is important to have an understanding of the limits of the magnetic field, and what it will pick up while scanning. Radiation therapy technicians also serve as an important presence when distinguishing markers for blood clots and calcification, while the actual patient is under, they are the guide through the processing and procurement of the trial. From these modifications the success of the treatment has presented a rate from 84%-96%. Acknowledging the importance of placement in the markers, the method is effective and promising for the future of radiation therapy. Looking ahead, the medical world has an unprecedented standard to provide honest and true medicinal work for patients of the world. Working with these new technologies and methods will open the gates to a more effective and safer world to live in. cancer free.

Author: Beau Lawrence