Sharp Shots
New MRI-Linear Accelerator allows for better precision in radiation treatments
For radiation oncologists and their patients, margins make all the difference.
Narrowing the focus of radiation beams, aimed at cancer, by a few millimeters means less damage to surrounding tissues and organs.
MRI guided adaptive radiation therapy
The University of New Mexico Comprehensive Cancer Center has added new technology that will allow radiation oncologists to target tumors more precisely, make adjustments as needed and potentially save patients from multiple appointments and CT scans.
The UNM Comprehensive Cancer Center recently installed an MRI-linear accelerator (MRI-LINAC), a machine that combines the clarity of magnetic resonance imaging with targeted radiation therapy.
It is the only MRI-LINAC in the state of New Mexico and a foundational piece to the UNM Comprehensive Cancer Center’s recent expansion. It is one of approximately 100 operational in the world. The technology is transforming how radiation oncologists deliver radiation therapy.
David Lee, MD, PhD, medical director of radiation oncology at the UNM Comprehensive Cancer Center, said the new machine was installed in April and, as of this writing, 10 cancer patients — six prostate cancer, three pancreatic cancer, one rectal — have been treated so far with many more scheduled.
MRI-LINAC is particularly useful for prostate cancer. Other potential uses include cancers of the pancreas, liver, kidney, or limited metastatic disease. Additional indications for MRI guided adaptive radiation therapy are rapidly expanding.
These cancers are typically found near other organs and soft tissue, where minimizing collateral damage from the radiation beams is of paramount importance.
Under conventional treatments, patients undergo CT scans to locate tumors one to two weeks before, then radiation oncologists plot how to target them with beams of radiation on a separate device.
If things change between the time of the initial CT scan and the radiation appointment, a new CT scan must be ordered which can add days to the process.
Because MRI-LINAC incorporates MRI technology, radiation oncologists can take an image on the day of the radiation appointment and make plan adjustments as needed.
“It allows us to see more clearly,” Lee said. “It allows us to be much more precise and develop personalized therapy for our patients.”
Things can also change in a patient quicker than the time between the MRI scan and radiation.
In prostate cancer, for example, changes in the bladder or bowel during the procedure have the potential to move the tumor. Under traditional circumstances, such movement could cause the radiation beams to miss their target. It’s part of why radiation oncologists target a wider area around the tumor. That creates larger margins around the tumor, which means more healthy tissues could be exposed to the cancer-killing radiation.
