• extracranial radiosurgery;
  • fiducial markers;
  • interventional radiology;
  • radiation oncology;
  • stereotactic body radiation therapy


Fiducial marker (FM)-guided stereotactic body radiation therapy (SBRT) allows for precise targeting and delivery of radiation to a tumor site. In this article, we briefly discuss SBRT, provide examples to describe CT-guided FM placement to guide SBRT, and discuss some of the associated risks and benefits. This article serves as a pictorial review for body imagers and interventional radiologists who perform CT-guided procedures and interpret diagnostic studies for oncology patients. CT-guided FMs were placed in patients who were appropriate candidates for SBRT. One week following placement, patients underwent diagnostic CT and/or MR examinations in order to include the FM data in the development of a treatment plan. From October 2007–November 2009, a total of 89 patients were implanted with FMs. Sites of implantation included lung, liver, bone, chest and abdominal wall, and peritoneum/retroperitoneum. Complications included pneumothorax and FM migration. Twenty-one patients (33%) with lung FM placement experienced at least a small pneumothorax and 6 patients (9%) required thoracostomy tubes. FM migration occurred in 5 patients (8%) with lung placement. SBRT provides a safer and more effective alternative to conventional radiotherapy, and CT-guided FM implantation of tumor sites increases the precision of SBRT. Technical improvements in FM placement can limit the complications associated with the procedure and further enable highly localized tumor therapy.