Presented by Patricia Sponseller, MS, CMD, RT(R)(T)
Medical Dosimetrist
The University of Washington

From the AAMD Virtual 45th Annual Meeting
July 6 -10, 2020

NOTE: If you earned CE Credits for this session during the AAMD Virtual 45^thAnnual Meeting, you will not be eligible to earn CE Credits for it again.

Metastases to the spine are a common complication in cancer patients. These metastases can result in compromised function in these patients resulting in pain and paralysis with loss of organ function. Stereotactic spinal radiation therapy is an emerging treatment technique for spinal tumors. In general, well-established guidelines for spinal cord tolerances have been established. However, spinal cord and central spinal fluid motion dosimetry have not been considered.
Dynamic cardiac-gated balanced fast field echo magnetic resonance imaging (MRI) was obtained in addition to conventional MRI imaging for 17 patients that were treated with volumetric arc therapy (VMAT) spine stereotactic body radiation therapy (SBRT) with spinal tumors.
Dice coefficients were analyzed for the spinal cord in conventional MRI versus the dynamic studies. A dosimetric analysis of the maximum spinal cord dose was reported.

The spinal cord shows inherent motion resulting in measurable dosimetric effects. A recommended planning risk volume (PRV) margin should be added to the spinal cord as an expansion to incorporate motion and ensure that the spinal cord is not overdosed.

Learner Outcomes:
1. Explain the dose limitations to the spinal cord for spinal stereotactic body radiation therapy
2. Discussion and assessment of the motion of the spinal cord
3. Recommended planning organ at risk margin

Educational Level: Intermediate

Presenter:
Patricia Sponseller, MS, CMD, RT(R)(T) is a medical dosimetrist at the University of Washington in Seattle. She is author and co-author of a number of publications. Her research focuses on near miss and incident learning for cancer patients that are undergoing radiation therapy treatments.