Initial Experience with the Siemens Magnetom Free.Max for GYN Brachytherapy: How Low Can We Go?
Abstract
Purpose
To share our initial clinical experience using the Siemens MAGNETOM Free.Max low field strength (0.55T) scanner for gynecological brachytherapy, including establishing sequences, assessing geometric distortion for a titanium tandem and ring (T&R) applicator, and providing images from our first clinical case.
Methods
Following GEC-ESTRO and AAPM TG-303 guidelines for imaging sequences, T2 images were acquired using the Free.Max scanner using a female volunteer. The optimized T2 protocols were then used to image a titanium T&R applicator encased in gelatin. The phantom was also imaged using a CT scanner to quantify geometric distortion. Following this validation work, our first patient case was performed.
Results
For volunteer scans, scan times were approximately 5 minutes per sequence, and the images were found to be clinically acceptable by our physician. For the T&R applicator in a gelatin phantom, artifacts were observed at the tip of the tandem and at fixation points in the applicator. However, use of the applicator solid model can mitigate the geometric error caused by this distortion. For patient T2 images, there was little contrast between the tandem and hypo-intense cervical tissue, making digitization using MRI alone challenging.
Conclusion
T2 images can be acquired with a low field strength MRI scanner to aid in GYN brachytherapy treatment planning.