Dalhousie researchers use 3D printing to revolutionize how cancer patients receive treatment

Dr. James Robar found that using a radiation-delivery device called a bolus lacked efficiency and accuracy. So he set out to find something more suitable. 

0 November 27, 2017
Staff

Dalhousie’s Dr. Jame Robar is looking to revolutionize how cancer patients receive treatment, making it more accurate, efficient and comfortable for patients, — and he’s using 3D printing to do it.

In 2012, Dr. Robar noticed that, although most steps are highly automated, there are manual process that can be improved. He discovered that using a device called a bolus — a layer of tissue-equivalent material placed on the patient’s skin during treatment that assists in providing the optimal dose of radiation — lacked efficiency and accuracy. So he set out to find something more suitable.

photon bolus dalhousie

A 3D printed photon bolus for use in treatment in the chest wall.

For the most part, the bolus is made out of a rubbery material called SuperFlab.

“The SuperFlab doesn’t always conform to the surface very well,” says Dr. Robar, who is a professor in the Faculty of Medicine. “This may cause air gaps, which inadvertently decreases the dose of radiation to the surface.”

Radiation therapists have sometimes used lower tech materials like wax, linen and tape to make it fit better.

“If you tour a clinic like this, you’ll see rooms that look like arts and crafts studios, where radiation therapists are trying to be sculptors essentially and build things for the patients,” says Dr. Robar. He goes on to explain that there are some consequences to this, specifically the limited accuracy in many cases. It can be extremely time consuming for not only the patient but staff members as well.

With 3D printing becoming increasingly more accessible, Dr. Robar saw an opportunity. One of the advantages of using additive manufacturing is the ability to make patient-specific devices using existing CT images that are acquired for patients as a part of standard procedure.

With a Proof-Of-Concept (POC) grant from Springboard Atlantic, Dr. Robar and his team purchased their first 3D printer, and began creating four different devices.

Electron Beam Therapy

Dr. Robar and his team explored how technology from a linear accelerator, which produces electron beams, can be used to treat tumours closer to the surface of the patient.  Shiqin Su, one of Dr. Robar’s students in the Dal Medical Physics Graduate Program, developed an algorithm that produce a 3D printed bolus that will modulate the energy of the electron beam, tailoring the treatment to the patient.

“For this application, we need to produce a dose distribution that conforms to the tumor, by varying the depth of the bolus over the tumour, depending on the depth of the tumour below the surface,” says Dr. Robar. “As a result, we produce a dose distribution that matches the shape of the tumor, and much of the healthy tissue is spared.”

Photon Beam Therapy

The team researched the effectiveness of  x-ray photons used in radiation therapy, which approximately 100 times more energetic than x-rays used in imaging, and are designed to kill cancer cells to design their 3D printed photon bolus. The device used during treatment of the chest wall for patients who have received mastectomy. An adequate radiation dose must be delivered to the surface of the chest wall, and Dr. Robar’s team has recently completed an in-house study to evaluate the new technology for that indication.

“One of my favorite uses of photon bolus was for a patient who had a tumor on his nasal septum,” says Dr. Robar. “He had undergone surgery but the tumor recurred, so we wanted to treat him using photon radiotherapy. The patient hadn’t been to our clinic before but he had a previous CT imaging for diagnoses and follow-up with his surgery.”

Dr. Robar was able to follow this example and pull his CT scan to design a bolus which fit perfectly in his nose before he even stepped foot in the clinic.

“We put topical anesthetic on it, and it fit his nose perfectly.” says Dr. Robar, “We could verify that because he had to have a CT scan that day. It worked really well. He had 30 treatments with this device and by the end of his treatment course, he would hop on the treatment bed, grab his 3D printed nose bolus, insert it himself, snap it together and he was ready to go.”

Immobilization Device

The next application is an immobilization device, which was specifically designed for breast cancer treatment for an intact breast. Usually, this treatment is administered over 16 to 25 weekdays in a row.  With breasts being highly mobile, it can cause an inconsistent dose of radiation to be delivered over this period of time.

The team developed a bolus that would act like a shell, and use a highly stiff version of 3D printing materials to keep the breast in place. 3D printing enabled the team to create a complex but hollow structure that is tailored to the patient. which limits the skin dose and the associated severe toxicity.

Brachy therapy

Brachy therapy treats tumors on both the inside and the surface of the patients by delivering radiation to the tumor through a radioactive source.

The “Freiburg Flap” is most commonly used for treating tumours near the surface of the patient. It consists of a beaded sheet that must be manually affixed to the patient by sewing to a mask or cast. Catheters pass through these beads, which allows the application of a radioactive source to treat a tumour on the patient.

One of the challenges with this device is that the blanket of beads needs to properly conform to the anatomy of the patient.

This is not an easy task, and Dr. Mammo Yewondwossen, also on the Medical Physics team, thought that this process could be improved by 3D printing a custom applicator. Another Dal Medical Physics Graduate Student student, Scott Clarke, helped develop the technology for this particular device.

All of these applications have been shown to greatly enhance the accuracy and efficiency of the radiation treatment process. The next step is to put it in the hands of clinicians.

Through the research and discoveries, the team launched a start-up company called 3D Bolus, to develop a product, including software that will enable practitioners to create photon and electron boluses, low-density immobilization and brachytherapy surface applicators.  The application is bundled with a 3D printer.

“The team has gone to multiple industry trade shows, including big ones that are part of conferences every year in the states, Canada, Europe, and there’s been a resounding response to this technology,” says Dr. Robar.

Currently version one of the product has been developed and has secured CE Mark clearance. The technology has been deployed in clinics in Dublin, Ireland and Tel-Aviv, with research versions in Chicago, San Francisco and Halifax.

“The hope is for this to become the standard model of treatment. In order to achieve that, we have to make this as practical and reliable as possible, otherwise we’re not going to meet that goal,” says Dr. Robar.

Going forward, the company’s approach will be to bring in 10 founding clients who will be the first in the world to use the technology in the clinic and to assist with testing and further development.

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