Reimagining Radiation Therapy: The Rise of 3D Printed Bolus

As a prominent 3D printer manufacturer, we’ve seen firsthand the leaps and bounds made in the field of 3D printing, particularly in its affordability and efficiency. A fantastic illustration of this is the production process of a 3D printed bolus, a device used in radiation therapy.

In the realm of radiation therapy, challenges often emerge due to the “skin-sparing” effect, wherein high-energy X-ray beams hit their maximum radiation dose only after penetrating to a certain depth within human tissue. While this proves effective for deep-seated tumors, it limits treatment efficacy for cancers located near the skin surface. A typical solution to this involves placing a tissue-equivalent bolus on the skin’s surface. Traditional boluses, however, often struggle to achieve a perfect fit, resulting in inconsistent radiation doses.  3D printing has enabled the creation of better-performing boluses.

The 3D-printed bolus stands out for its advantages over traditional boluses. It provides a uniform thickness, minimizing ray scattering and ensuring an even dosage distribution. It precisely covers the target area, reducing unnecessary radiation to distant organs. Additionally, it facilitates precise control over the bolus shape- enhancing the delivery of the therapeutic dose while safeguarding organs at risk.

The Material Science of 3D-Printed Bolus

Creating an effective bolus for radiotherapy isn’t just about achieving perfect skin contact—it’s also about the selection and implementation of the right materials. Considering the physical characteristics, biocompatibility, safety, and comfort of the material, as well as the infill ratio of the bolus under various manufacturing processes, is crucial.

Traditionally, polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) have been the materials of choice due to their high filling ratios, similar densities to water, and ease of 3d printing. However, while these materials have their merits, they also have limitations, particularly when it comes to patients with sensitive skin or open wounds. TPUs (thermoplastic polymers such as Wolfbend) are the preferred material of many Airwolf 3D radiotherapy partners. 

Silicon, on the other hand, has demonstrated impressive flexibility and durability, showing no signs of cytotoxicity or skin irritation.  Some technicians do not print the bolus itself but instead print a mold in ABS or PLA to create a silicon bolus.

The Production Process of the 3D-Printed Bolus

The manufacturing a 3D-printed bolus involves steps that ensure the highest level of accuracy and patient-specific customization. Initially, the desired radiotherapy bolus area is identified on the patient. Using a CT scan, a model of an “external contour” is created and expanded by the required thickness of the bolus. The material is then shaped to only cover the treatment area, resulting in a precise contour of the desired bolus.

The contour model is saved as an STL file (a language the 3D printer understands). While 3D printing a solid piece of plastic can be challenging due to the risk of deformation, Airwolf 3D printers are designed to print such parts with minimal warpage and maximum layer-to-layer adhesion.  Higher infill leads to a more densely packed lattice, which improves the homogeneity of the bolus and, consequently, the dose distribution on the patient’s skin.

Once the bolus is printed, the fitting degree is verified for satisfaction. A new radiotherapy plan is then developed in the treatment planning system (TPS) using a fresh CT scan with the 3D bolus.

3D Printing in Pre-Clinical Evidence

Recenly, scientists Shin-Wook Kim and Jae Won Park found that 3D printed boluses improved the accuracy of radiation therapy by ensuring the precise dosage and coverage of the target area.

In studies involving nose and head lesions, 3D printed boluses showed a marked improvement in delivering the exact prescription dose. For instance, in a study led by Kim, the minimum dose to the nose increased from 25.4% without a bolus to 90% with a 3D bolus. Meanwhile, Park’s study found that the volume receiving 90% of the prescribed dose for head lesions increased from 57.8% without a bolus to 99% with a 3D bolus.

Other studies also demonstrated that 3D printed boluses could overcome the dose reduction caused by the air gap between the bolus and the skin surface. For example, So-Yeon Park’s research on postmastectomy radiotherapy compared the 3D printed bolus with a commercial one. The study found that the dose errors with a commercial bolus were significantly higher than with the 3D printed version, demonstrating the superior precision of 3D printed boluses.

In summary, these pre-clinical studies provided strong evidence that 3D printed boluses could revolutionize radiation therapy. They ensure better coverage of the target area and improve the accuracy of dosage delivery, potentially making radiation therapy safer and more effective. 

Bringing Cost-Effective, High-Quality Bolus Production to Your Lab

To wrap up, the landscape of 3D printing in medical settings is advancing at an impressive pace, becoming both more affordable and efficient. The tangible benefits of these advancements are most notably seen in the production of 3D printed boluses, which provide a more cost-effective, timely, and personalized solution for patients in need of radiation therapy.

At our company, we don’t just observe these advancements—we’re a part of making them happen. We offer a comprehensive bolus manufacturing solution that includes not only the necessary equipment, such as our direct drive printers, but also the flexible materials and the essential Wolfbite adhesives. This complete package ensures you have all the tools at your disposal to effectively create a flexible bolus.

Our most popular material among medical customers is the Wolfbend TPU. This flexible material stands out due to its incredible durability, flexibility, and low skin irritation, making it ideal for the production of boluses. Yet, we understand that the process of 3D printing a bolus comes with its unique challenges, such as dealing with its organic shape and complex geometry, printing flexible materials, and ensuring adherence to the print surface.

That’s where our unique additive manufacturing kit and specialized training come in. We’ve honed in on improving the bolus manufacturing process, addressing these challenges head-on with features such as chamber heaters, a heated bed, an air filtration system, bed adhesion materials like Wolfbite, and support materials. Furthermore, we’ve integrated a dual-head direct drive flexible material extrusion system and finely tuned slicing software settings to handle those organic, complex geometries with water-soluble support material (HydroFill).

Our equipment is already trusted and utilized by numerous radiology departments across the US, and we’re eager to extend this trusted service to your lab. With our equipment and training, there’s no need to fear the adoption of this cutting-edge technology. Embrace it and witness firsthand the benefits it can bring to your practice and, most importantly, to your patients.

At the end of the day, our goal is to make the future of medical 3D printing as accessible, efficient, and patient-friendly as possible. That’s the future we envision, and we invite you to be a part of it.

We’re excited to be a part of this journey in advancing medical technology and look forward to further advancements in this area. Stay tuned to our blog as we continue to explore and explain the cutting-edge world of 3D printing!

We’re thrilled to announce that we’re in the process of crafting an all-encompassing training course focused on 3D printing bolus devices using Airwolf 3D printers. If you’d like to stay updated and join our interest list, simply shoot us an email at Once ready, the training will be accessible (free of charge) at

Interested in learning more about our exceptional range of equipment and supplies? Drop us a line at One of our 3D printing specialists will promptly get back to you with all the details you need. We’re here to help you make the most of additive manufacturing!