Future of Radiation Oncology
Since engineers assembled the first primitive external beam radiotherapy devices in the early 20th century, the radiotherapy techniques available to oncologists have advanced exponentially, becoming safer and more effective each year. The ability to directly treat cancers deep in the body with focused beams of radiation, in combination with remarkable diagnostic and systemic innovations, has resulted in radical improvements in the prognoses of those diagnosed with nearly every type of cancer. With these tools available at the Payson Center for Cancer Care, many cancers have become a treatable chronic condition.
During the past twenty years, the integration of increasingly sophisticated digital control and detailed imaging systems has enabled continuous refinements in the precision of the radiation’s delivery. While the technology generating the radiation has not fundamentally changed, it can be delivered with highly individualized accuracy that would have been considered impossible at the turn of the century. Where radiation would have previously damaged healthy tissue in an effort to reach cancer, now the healthy tissue can—through the use of a number of different techniques available at the Payson Center for Cancer Care—be largely spared.
Modern radiation delivery systems can be adapted to the natural motions of the human body—breathing, the beating heart, the errant twitch—to further reduce collateral tissue damage. As a result, patients can be treated with fewer visits and receive a higher dose of radiation, resulting in better treatment outcomes for specific types of patients. Many of these advanced techniques such as respiratory gating, lung and liver stereotactic radiosurgery, and deep inspiration breath hold (see descriptions), are currently available at the Jim & Marianne Cook Radiation Therapy Department.
There is no reason to think that this progress will slow. Over the next twenty years, the technical refinements that have changed the nature of radiotherapy will continue to advance. In 2020, 18 million people were diagnosed with cancer. By 2040, that number will grow to nearly 30 million. With the innovations that lie ahead, the Payson Center for Cancer Care continues to strive for a singular goal: eliminating mortality associated with cancer.
Respiratory Gating
Respiratory gating represents the culmination of what sophisticated computer controls, advanced linear accelerators and high-quality imaging can accomplish. With this innovative treatment approach, radiation oncologists at the Payson Center for Cancer Care can now track and treat moving tumors in real-time. As patients breathe, the liver and lungs naturally move with the diaphragm. For patients with liver or lung cancers, a 4-dimensional CT (computer tomography) is performed to visualize the tumor in motion during breathing. Then, radiation therapy can be synchronized to turn on/off, depending on where a patient is in the respiratory cycle – whether it’s during inhalation or exhalation. When the tumor moves into a predefined position, the radiation turns on, and when it falls out of range, it turns off. With respiratory gating, radiation oncologists can maximize the radiation dose to the tumor with stereotactic radiosurgery, where higher doses of radiation are delivered in fewer treatments while limiting damage to surrounding normal tissue. Remarkably, the treatment outcomes from these non-invasive outpatient radiosurgeries are comparable to those of surgery.
Deep Inspiration Breath Hold During Treatment
With left breast radiotherapy, treatment was previously delivered throughout the respiratory cycle. Every time the patient exhales, the breast comes to rest very close to the heart (below, left). When the patient inhales, the breast rises away from the heart. With Deep Inspiration Breath Hold or DIBH, patients are coached to inhale deeply and hold their breath during treatment. At these moments, the diaphragm has pushed the heart away from the chest wall, creating a safety gap. Radiotherapy is then delivered only during those times when the patient is holding their breath, maintaining that safety gap and sparing the heart from excess radiation exposure.
Liver Stereotactic Radiosurgery
Liver radiosurgery harnesses the technological advancements and therapeutic advantages of DIBH and Respiratory Gating. In standard treatment of the liver, the radiation dose spreads outside of the target to the surrounding healthy liver tissue. When utilizing respiratory gating in conjunction with stereotactic radiosurgery, radiation oncologists can precisely treat a liver tumor while it is moving during the respiratory cycle, thereby minimizing liver damage (below, right). The Payson Center for Cancer Care is one of just a few cancer centers in New Hampshire that offers stereotactic radiosurgery of the liver.
Tattoo-less Breast Radiation Therapy
For decades, radiation for breast cancer has relied on permanent tattoos that mark the treatment area to provide consistent reference points for use with lasers to position patients in the treatment room. These tattoos, which consist of safe but permanent ink placed just below the skin, facilitate consistent alignment and treatment from one day to the next.
The Jim & Marianne Cook Radiation Therapy Department at the Payson Center for Cancer Care offers breast radiation therapy for selected patients without the use of tattoos. Surface Guided Radiation Therapy with AlignRT uses 3D cameras with sensors and light projected onto the patient's skin surface to capture real-time 3D surface data, which is then aligned to the planned treatment position. This system has the ability to track a person's position in real-time with millimeter accuracy. This state-of-the-art technology is proven to be as accurate as radiotherapy using permanent tattoos and has the added benefit of a shorter treatment time each day.
