31 Using a 3D Fiducial Marker System to Advance the Use of 3D Accelerated Partial Breast Irradiation

Lori Anthony, PA¹

¹JFK Medical Center, Lake Worth, FL.

Background

Currently, no reliable techniques are available to accurately identify a lumpectomy cavity volume, creating difficulty for radiation oncologists in targeting the cavity volume as part of a treatment regimen. As such, oncologists must expand the planned target volume using a larger area or volume of radiation, which exposes a greater volume of normal tissue and makes it unclear if the postoperative tumor bed cavity has been treated with the intended goal.

Materials and Methods

A metallic marker woven inside a dissolvable suture was positioned in the lumpectomy cavity at time of surgery by the operating surgeon for pinpoint accuracy. After removal of the tumor, 4 to 6 sutures were placed in the wall of the cavity (superior, inferior, medial, lateral, anterior, and posterior).

During the 6- to 8-week period following surgery, weekly orthogonal kilovoltage images were acquired using the Varian Onboard Imager system and compared with orthogonal digitally reconstructed radiographs generated from the simulation CT. The matched image sets were then overlaid for verification of fiducial position relative to the surgical cavity by the radiation oncologist.

Results

During clinical trials, all safety and performance end points of the human study were met as intended, as follows:

• No study subjects reported any adverse effects: pain, inflammation, infection, or tissue reaction with implantation of the markers.
• The Accusyte 3D Fiducial Marker system demonstrated ability to stay on site and to produce accurate localization and excellent visualization as provided by the 3D approach.
• All 98 radiographic images obtained during the study were clear, allowing for optimal localization and easy visualization of markers without any significant migration from initial target site.
• Images taken 1-year post implantation showed that markers hadn’t moved and were clearly visible in radiography.
• Surgical Radiation Products is continuing third year of follow-up with mammographic images, and again visualization of the markers without significant migration from initial site has been confirmed.
• The Accusyte suture will eventually dissolve, leaving the markers for a lifetime of follow-up.

Conclusions

Use of a 3D Fiducial Marker will allow accurate visualization and delineation of the cavity volume with high degree of consistency and reliability. The Accusyte 3D Fiducial Marker system has eliminated the localization problem. The markers offer a precise, stable target for postoperative radiation. They are more effective than loose markers, clips, or other competitive products.

Expert Commentary