How is surface guided radiation therapy used to deliver breast cancer treatments at Maastro Proton Therapy?

The state-of-the-art Maastro Proton Therapy is the first proton therapy system in the world to feature a new integrated CBCT and surface-image guided radiation therapy (SGRT) workflow developed in partnership between C-RAD and Mevion Medical Systems. This new workflow combines a room-mounted CBCT with C-RAD Catalyst PT to verify patient setup in both an imaging position and a treatment position.

Maastro Proton Therapy, a partnership between Maastro and Maastricht University Hospital, began treating patients in early 2019 using Europe’s first compact proton system, the Mevion S250i Proton Therapy System. Since opening, the center is treating 25 patients per day and has treated cancer of the head and neck, breast, brain, lung, hematology and esophagus, with breast cancer accounting for approximately 25% of its cases to date.

How Catalyst PT has improved the proton therapy workflow

Maastro Proton Therapy uses four Catalyst PT cameras to verify the patient in two separate patient positions. The first set-up position is the treatment position, where three of the four Catalyst PT cameras are placed to get a clear view of the patient. The second position is the imaging position. The cone-beam CT imaging ring is positioned so that it does not interfere with the proton gantry and an additional Catalyst PT camera is placed to provide sufficient patient coverage and avoid interference.

The C-RAD software can compare the patient surface scans acquired during the CT scan with the surface scans acquired in the in-treatment-room treatment and imaging positions to verify patient setup and monitor patient position during gated treatment delivery.

Gloria Vilches and Esther Kneepkens, medical physicists in charge of the clinical implementation of Catalyst PT in the Maastro Proton Therapy center, explain why their center opted for the use of Catalyst PT: “Catalyst PT not only supports accurate patient positioning within the treatment room itself, but also reduces treatment set-up time, which helps us improve patient care and patient throughput. By the end of the year, we hope to have expanded the use of Catalyst PT to gated treatments, which is relatively unique in proton therapy. For breast and lymphoma patients, this will allow us to safely treat in voluntary deep inspiration breath-hold, further reducing the dose to heart and lungs. Additionally, if patient movement is detected beyond a certain clinically defined threshold, Catalyst PT will interrupt the treatment beam, giving the clinical team the ability to make patient adjustments and then resume treatment.” Lung and esophagus are the next treatment sites for which the potential benefit of using Catalyst PT will be investigated.

How the Catalyst PT works with the Mevion S250i Proton Therapy System

C-RAD’s surface guided workflow has been fully validated for use with the Mevion S250i Proton Therapy System, and includes:

Using 4 cameras to scan the patient in multiple couch positions, not only in treatment positions but also in additional in-room mounted imaging ring
Using multiple cameras with large field of view to maximize the patient coverage and to avoid interference from the treatment nozzle in half-gantry, full-gantry, and fixed beam vaults

Reducing treatment setup time by providing both patient centric posture corrections and automatic 6 degree-of-freedom couch shift corrections.
Enabling accurate patient positioning in treatment position, in addition to other typical 3D imaging modalities.

“This integration is the first of its kind in proton therapy. Interlocks between Catalyst PT and Mevion are interwoven at the system level to ensure the systems communicate automatically with each other,” explained Armin Langenegger, director of product solutions at Mevion. “Our partnership with Maastro and C-RAD ensures that proton therapy patients are able to receive their treatments with a high level of confidence in positioning and accuracy,” he added.

Does C-RAD support external beam treatments with traditional linear accelerators?

Maastro has also integrated Catalyst HD into its linac workflow as well and it is used for complex hypo fractionated treatments in deep inspiration breath-hold (DIBH) for liver metastases and lymphoma. The system has also proven its value for non-coplanar stereotactic radiosurgery treatments (SRS) of patients with one or more brain metastases. For other complex treatments such as for spinal metastases, extremities and indications where set-up accuracy before and during treatment is vital, the C-RAD system is used, says Michel Öllers, Medical Physicist at Maastro and an international expert on Surface Guided Radiation Therapy.

The team concluded: “Our entire program is grounded in making sure that we have the best technology available to support accurate and precise cancer treatments for our patients, with a clear focus on complex treatments and moving targets. With C-RAD, we found a partner who can not only help us implement high-precision radiation therapy, but who also works closely with us to make ongoing enhancements to further improve our entire workflow to benefit patients.”

To learn how C-RAD can support external beam treatments with both traditional linear accelerators as well as proton therapy workflows, watch the educational series or contact your local C-RAD clinical specialist.