Treatment Accessories for Proton Therapy are Different. Here’s Why.

The unique characteristics of proton compatible immobilization systems

Proton therapy delivers treatment doses in a different way than X-ray or electron radiation therapy systems. For this reason, proton therapy requires specially designed treatment accessories to ensure safe, effective, and accurate treatment to patients.

Here’s a brief overview of the differences in therapy systems and what goes into developing proton-compatible accessories.


Why can’t I use the devices I already have on my proton therapy system?

When used on X-ray or electron radiation therapy systems, treatment accessories have very little impact on the treatment delivered. Dose is delivered along a path to a depth determined by the X-ray or electron energy level. The depth of delivery is not significantly impacted by thermoplastics, plastics, or carbon fiber accessories typically used in radiation therapy.



Proton therapy is different. Materials placed in the proton path can cause the delivered dose to miss the target.

Instead of delivering radiation continuously along a path, most of the proton therapy dose is concentrated at the end of travel. The Bragg peak makes proton therapy much more precise and accurate, but introduces additional challenges to delivering a patient treatment.

Since patient accessories are placed in the proton path, choosing the wrong devices can lead to patient mistreatment.


What are some of the design and manufacturing challenges for proton therapy accessories?

Creating accessories for proton therapy requires the use of new materials and the development of new designs.

Orfit’s head only single layer masks allow for a planning treatment volume (PTV) margin of 1 mm in proton therapy.


Materials must be homogeneous and time stable. Any non-homogeneous materials or inconsistencies in the material’s density can cause the proton dose depth to change.

Any materials that cannot be imaged accurately and cannot be given a water equivalent thickness (WET) during simulation must be avoided.

Aerial Couch Top for proton therapy

Designed for proton therapy, the Aerial Couch Top has only a 0.5 mm water equivalent thickness change per 10 cm distance.


Optimal design choices

Devices should be designed to incorporate new materials and minimize the impact that small changes in patient setup have on treatment delivery.

Where honeycomb structures may have been designed into standard devices to provide structural strength, proton compatible devices are designed with thin layers of carbon fiber or a solid, lightweight core. To eliminate large changes in material density over a small distance, material edges must be replaced with gradual slopes.


Orfit Proton Solutions

To help overcome these challenges, we have implemented significant design and manufacturing processes to produce a complete line of custom accessories specifically for proton therapy.

Orfit systems are widely used throughout the US in most major proton therapy centers, so you can have high confidence in the Orfit solution to help deliver safe and effective proton treatments.

To learn more about our complete line of proton therapy accessories, visit


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