Markerless radiation erases a reminder and improves breast cancer therapy
October 30, 2023
Breast cancer almost always leaves its mark on patients. Along with surgical scars and changes in breast size and shape, medical tattoos or semi-permanent marker dots and lines were drawn on the patient’s chest to align radiotherapy beams, like checkpoints on a map.
Seeing those marks was a constant reminder for patients of the journey they never asked to take. Many reported feeling self-conscious wearing dresses or blouses that might reveal the dots or lines, adding further discomfort after enduring treatment.
We knew there had to be a better way. So in 2013, we embarked on a 10-year initiative to deliver markerless radiation therapy to our breast cancer patients, and today it has become the standard of care at the Department of Radiation Oncology at UT Southwestern’s Harold C. Simmons Comprehensive Cancer Center.
Thanks to the determination and innovation of our medical physicists and radiation oncologists, every one of our patients gets access to markerless, surface-guided imaging, along with other internal imaging, that precisely zeroes in on their treatment site. Additionally some patients qualify for adaptive radiation therapy, which allows us to make real-time adjustments to their radiation plan for changes such as tumor size and position, maximizing precision.
UT Southwestern is the only center in Texas and one of few in the world to use this innovative dual approach, inconspicuously and privately treating our patients’ breast cancer without marking them as under therapy.
How surface-guided radiotherapy works
For each radiation therapy session, we index the patient’s body shape to the treatment couch, using their most recent CT scan as a guide. We do this so all the radiation therapy beams follow the geometry of their personal map, treating the cancer precisely and avoiding healthy tissue.
The map is generated by our motion-tracking video system, AlignRT developed by VisionRT, which uses three ceiling-mounted 3D cameras to beam a patterned light grid onto the patient’s chest. The system tracks thousands of points on a patient’s skin and matches them to the patient’s initial CT scan with submillimeter accuracy.
Radiation therapists monitor the system in real time and are alerted immediately if a patient moves – even slight movements such as breathing can move them 1-2 millimeters outside the radiation field. When this happens, the radiation therapist can turn off the machine and instruct the patient how to adjust to realign with their personal map.
We’ve been using surface-guided technology for 10 years with deep inspiration breath hold in left-sided breast cancer, in which patients fill the lungs with air and hold it for a few seconds to remain still and to buffer the heart from incidental radiation beam exposure. Our research, published in the Journal of Applied Clinical Medical Physics showed that using surface-guided breath-hold in left-breast treatment was at least as precise and in some cases more precise compared with standard breath-hold radiation therapy.
Now, we’re using the technology to its full capacity by eliminating the use of physical markings for patients with left- and right-sided breast cancer.
The radiation oncologist and medical physicist work closely together to plan each patient’s care. Medical physicists have a critical role – they work behind the scenes, calibrating the machines for each patient’s treatment plan and making sure every patient gets exactly the right dose in the planned treatment field. They manage the technology and delivery, while the radiation oncologist develops the treatment plan and works face-to-face with the patients.
Better breast cancer therapy with GammaPod
The use of this leading-edge equipment has the potential to improve patients’ quality of life by lowering toxicity, enhancing the overall appearance of the breast, and decreasing the number of treatments.
Choosing the best radiation therapy for every patient
With extensive technology at our fingertips, every UT Southwestern patient gets a truly personalized radiation therapy plan using surface-guided technology. We select the best-fit machine for each patient based on the size and positioning of their tumor and surgical site, skin condition, and the location of their heart, lungs, and ribs.
We have one of the largest stereotactic partial breast programs in the U.S. and are pioneers in S-PBI, with the most sophisticated radiation therapy technology available, all of which integrates with the markerless system. Each type of machine is highly effective and precise, and each works a bit differently:
- Ethos: Combines artificial intelligence with adaptive therapy to account for day-to-day changes in the size, and location of tumors to give the best possible treatment during each treatment session.
- Unity: Combines magnetic resonance imaging with a linear accelerator giving superior visualization of the soft tissue, which is especially useful in a pre-operative setting.
- CyberKnife: This machine uses a linear accelerator mounted on a robotic arm to focus beams of radiation at a tumor from multiple directions.
- GammaPod: Using principles of stereotactic radiotherapy to deliver higher doses in one to five treatment fractions with cobalt sources, GammaPod uses a vacuum-assisted breast cup to provide precise treatments and immobilize the breast during radiation. UT Southwestern was the first center in Texas and the second in the world to make the GammaPod technology available to patients.
Future of markerless breast cancer radiation therapy
As the only NCI-designated comprehensive cancer center in North Texas, UT Southwestern is leading the movement of research and implementation for advanced radiation therapy techniques worldwide. Our breast radiation group had 23 breast cancer radiation research abstracts accepted at international medical conferences this year and participated in numerous talks to share our knowledge with the wider scientific community so they might be able to adopt our methods and improve women’s breast cancer treatment experiences and outcomes.
Meanwhile, our group won the coveted American Society for Radiation Oncology (ASTRO) translational research award, which is given to the top 1.5% of abstracts out of 2,000 submissions in the physics section at ASTRO. This shows the caliber of the research, technology, and type of radiation delivery that we’re providing to our community.
Our next steps include exploring how artificial intelligence may be used to help make treatment decisions. For example, how AI might help us estimate the potential heart, lung, or skin dose from a particular machine or condense the radiation planning timeline from one to two weeks to a single day. We are still developing our AI program, and we’re excited to present our early findings at the San Antonio Breast Cancer Symposium, which has accepted our abstract on the subject.
There are so many exciting developments occurring around breast cancer treatment right now, and we are proud to be at the forefront in advanced radiation therapy approaches. Our breast cancer patients are entitled to the most advanced and compassionate care – and we are proud to deliver it to them.
To discuss your options for breast cancer radiation therapy, call 214-645-8300 or request an appointment online.
