SIMAC: Learning about Linacs through Simulation


For over 40 years, linear accelerators, or linacs, have been used to treat cancer patients using radiation that targets cancer cells while sparing the healthy tissue surrounding the tumour. Until 2014, Medical Physicists, who are tasked with maintaining and performing quality assurance tests on linacs, had limited tools to learn about how these machines work on the inside. To enhance education about linacs, UTDRO Assistant Professor Marco Carlone and previous faculty member Miller MacPherson, along with collaborators from the University Health Network (UHN) and Trillium Health Partners have created SIMAC (simulation linac), a teaching tool that allows physicists and students to get inside the linac and learn how the different components affect the final output.

Dr. Marco Carlone, who is also a Medical Physicist at the Princess Margaret, explained that linacs are very sensitive and complicated machines. In the past when these machines were less reliable, medical physicists would often work directly with the engineers who assembled the machine to help with repairs and troubleshooting. Recently, however, linacs have improved in reliability and the collaboration between medical physicists and linear accelerator engineers has required much less direct contact.

In addition, students training in medical physics have very few learning resources related to linear accelerator operation at the engineering level. The only textbook available in this field, written by CJ Karzmark, is now 25 years old. As well, access to the linacs themselves is limited as the linacs are usually reserved for patient treatment and are too expensive to allow students to manipulate.

Since the launch of SIMAC, physicists have been able to access real-time simulations of beam formation in a linac. SIMAC essentially replicates the relationship between the beam production hardware and provides real-time feedback on beam manipulations without fear of breaking the machines.

Ms. Nicole Harnett, UTDRO Assistant Professor and Radiation Therapist at the Princess Margaret, runs a course called ATec (Accelerator Technology) through the Accelerated Education Program at the Princess Margaret. She explains the need for SIMAC. “It’s dangerous and expensive to allow students to manipulate beams in an actual linac. But with SIMAC, the learners are able to make beam adjustments and get real-time feedback on how the treatment changes.”

ATec is the only course in the world tailored to medical physicists that provides an intense and immersive environment to learn about linacs. It brings together medical physicists and accelerator service teams – two important groups of people who do not often interact in the clinical environment – to learn a common vocabulary and begin collaborating with each other. “This course provides important knowledge about the linacs to individuals who work with these machines daily,” explained Marco. “By using SIMAC, which is used in this course, the students and residents get an inside look at how the beam manipulations impact treatment.”

Although the ATec course is designed for medical physicists, it is also attended by linac service teams and employees from the Canadian Nuclear Safety Commission, Canada’s federal nuclear regulator. One of the learners who attended the ATec course recently said, “I found this course extremely useful. It really helped me understand all the topics we had discussed.”

To continue growing SIMAC, Marco and Nicole, along with their teams, received a UTDRO Collaborative Seed Grant in 2015 for a multi-institutional study. Through this grant, Marco was able to hire developers and project managers from the Techna Institute. The developers translated and optimized the MATLAB software that SIMAC ran on into a system that will run on any platform. Following this, the seed grant will be used to measure and assess the success of SIMAC.

All training programs have learning outcomes that include assessment of participant reaction, increase in knowledge, practice change and effect on patient outcomes. Nicole explained they already have anecdotal information that SIMAC is helping physicists. “There is a lot of interest from physicists around the world who are contacting us because they want to download the software, participate and collaborate with us.” Through the UTDRO Collaborative Seed Grant, the team will also be able to assess if SIMAC is having a measurable impact on learning and knowledge and if it is having an effect on their practice.

In addition to the development and measurement of SIMAC, Nicole explained that being backed by UTDRO has been crucial to creating SIMAC. “Through UTDRO’s support, we were able to create a strong foundation that will allow us to scale SIMAC to different centres around the world.”

“It also helped to provide credibility,” Marco added. “Since UTDRO runs the largest Physics Residency program in the country, launching SIMAC here first has provided a credibility that helped bring collaborators from other sites around
the world.”

To date, physicists from several large cancer centres such as Duke University and McGill have expressed interest in collaborating with Marco and his team. By keeping the software open access, Marco is encouraging other centres to collaborate with his team and help make the software as robust and adaptable as possible.

Marco explained how SIMAC can be adapted at any cancer centre or hospital: “We are disseminating SIMAC at our larger centres like Odette and Princess Margaret Cancer Centres as well as smaller centres such as RS McLaughlin Durham Cancer Centre (Oshawa), Simcoe Muskoka Regional Cancer Program (Barrie) and Stronach Regional Cancer Centre (Newmarket). By doing this, we want to be able to show that SIMAC can be used at any centre – big or small, academic or non-academic.” 

To find out more about SIMAC or to download it, visit




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