From the September 2017 issue of HealthCare Business News magazine
Integration of advanced imaging into radiation therapy (RT) systems has evolved significantly over the past several decades.
The goal has been to address a fundamental RT challenge: increasing certainty related to the location of tumor and surrounding normal tissue so that tumor dose can be maximized and normal tissue dose can be minimized. Use of cone-beam, CT-based image guidance to direct the RT beam, now a standard of practice, has contributed significantly toward addressing this challenge and is associated with some of the best treatment outcomes to date.
Use of high-field magnetic resonance imaging (MR imaging) provides arguably the best option for soft tissue visualization and would improve the ability to clearly discriminate between tumor and nearby healthy tissue. This would enable more precise targeting, allowing increased dose to tumor and decreased exposure to adjacent normal tissue. Because both tumor and normal tissue can move or change shape between, or even during, treatments, high fidelity imaging can be an important tool for adapting radiation treatments to these changes. Simultaneous high-field MR allows for real-time monitoring of tumor and normal tissue motion both between and during treatment sessions. This capability enables both daily and online adaptation of treatment to ensure correct dosing for each patient between and within treatment sessions.
While the use of high-field MR provides arguably the best option for soft tissue visualization, technical hurdles resulting from the impact of magnetic fields on the function of linear accelerators have heretofore prevented integration of these technologies. These impediments, however, have recently been surmounted, rendering high-field MR simultaneous with radiation delivery feasible. The resultant technology has the potential for providing unsurpassed image fidelity that can greatly improve RT care.
Another important benefit resulting from integrated high-field, MR-guided radiotherapy is its potential as an option for patients with tumors located near critical organs or in difficult-to-access areas requiring a level of accuracy and precision sometimes not achievable with traditional linear accelerators. An integrated system could expand the feasibility of RT to additional tumor types and more complex cases, and offer treatment options to patients who otherwise have very limited choices.
The improved dose targeting that can be achieved with an integrated MR/RT system may not only result in better treatment outcomes, but could also allow more radiation to be delivered over fewer treatment sessions, enabling development of shorter treatment regimens that are less burdensome to patients.
