Magnetic Resonance Image-Guided Brachytherapy Clinical Implementation and Experience

Image-guided adaptive brachytherapy is the new gold standard for treating locally advanced cervical cancer, replacing the traditional two-dimensional (2D) point-A concept. On 2021 the institution transitioned from conventional 2D-BT to a 3D image-guided program. Using an MRI scan for each fraction allows us to deliver treatments with a completely adaptive approach, in contrast to the conventional 2D-point-based BT. We present our initial experience and results for a 130-patient group, comparing reference-point doses to dose-volume histogram (DVH) parameters. With an 82 to 86 Gy prescription, volume-based 3D plans reached a mean of 85.32 Gy ± 2.87SD (standard deviation) to target, in contrast with 73.52 Gy ± 7.97SD received by reference A points. Mean doses to organs at risk (OAR) were within prescription limits. Optimizing treatment based upon delineated OARs and the actual target volume, together with DVH evaluations leads to maintaining tumor dose coverage without compromising doses to normal tissues. This has direct clinical implications to substantially improve rectal, sigmoid, and bladder dosimetry and reduce late toxicities.