Recent developments in imaging technologies and artificial intelligence are empowering a revolution in cancer radiotherapy. Personalized treatment plans can now deliver the optimal amount of radiation directly to the tumor while avoiding exposure of healthy tissues in order to minimize side effects. This unprecedented treatment precision is made possible by improvements in imaging techniques. Arjan Bel is the head of the Radiotherapy Physics group at Cancer Center Amsterdam. They are utilizing the latest technology to extract information from medical images to tailor the delivery and dosage of radiation
treatment.
On Thursday March 17, Arjan Bel – professor of Clinical Physics Radiotherapy at the University of Amsterdam, Amsterdam UMC - presented his vision on the role of imaging technologies in precision radiotherapy and other radiation-based cancer treatments. The inaugural lecture ‘See what we do, do what we see’ took place in the auditorium of the Old Lutheran Church in Amsterdam and could also be attended online.
Improving radiotherapy through research
The precise delivery of radiotherapy to certain tumors is complicated by the constant changes that occur in the human body. For example, bladder and bowel dimensions are dynamic, and changes can alter the location of bladder or colorectal tumors. In adaptive radiotherapy, these anatomical changes are visualized via advanced medical imaging techniques and artificial intelligence (AI) can calculate a personalized treatment plan almost instantly that adjusts the treatment to the current physiology of the patient.
Another challenge is the interference of breathing movements during radiation treatment. After some training and by first inhaling a supply of oxygen, healthy volunteers can stop their breathing movements for about 10 minutes, creating a more stabilized anatomy and a therapeutic window. However, the diaphragm still contracts over time due to uptake of oxygen from the lungs. As an alternative solution, research is now conducted with a mechanical ventilator to create a very calm and shallow breathing pattern to minimize movements.
Other forms of radiation-based therapeutics
Specialists at Amsterdam UMC have developed artificial intelligence that facilitates the delivery of an optimized radiation dosage to a tumor via brachytherapy. This type of treatment utilizes several catheters to deliver a radioactive substance into the tumor from distinct angles. Prof. Bel: “We developed AI tools that correctly indicate the exact delivery locations of the radioactive medicine and required dosage for brachytherapy. I am very proud of our team’s achievement.”
At Cancer Center Amsterdam, researchers in Prof. Bel’s department are boosting the effect of radiation by heating up the cancer cells. This hyperthermia treatment uses similar technology as the common kitchen microwave to heat tumor cells up to about 42 degrees celsius. Because cancerous cells are much more sensitive to heat than normal healthy cells, this can specifically induce the death of malignant cells. In addition, imaging technologies like MRI also have potential to monitor the temperature inside the tumor to identify areas that need more heat to reach treatment threshold temperatures.
Proton therapy
While standard radiotherapy relies on photon-energy to eradicate tumors, blasting cancer cells with energy delivered by protons is also an attractive option. In the Netherlands, recently three medical centers - Delft, Maastricht, Groningen – started using proton therapy.
“With protons you can regulate the delivery location much better as all energy is confined into a much smaller peak area,” explains professor Bel. “This type of therapy may be favorable to treat tumors in close vicinity to tissues of vital functional importance.” Due to the peak proton energy delivery, exposure of healthy tissue that surrounds the tumor can be avoided. Professor Bel: “With our imaging tools and mathematical modeling of radiation therapy, we can predict which patients are most likely to benefit from proton therapy.”
Proton therapy is not more beneficial for patients with cancer in general, and more traditional photon-based radiotherapy is just as effective. But to provide tailored care for patients with tumors that benefit from proton therapy, Amsterdam UMC collaborates with Holland Proton Therapy Center in Delft.
A drive to transform vision into reality
“The adaptive radiotherapy that we can offer to our patients today is a personalized and highly accurate temporal-spatial treatment modality which we could only dream of less than a decade ago,” says Professor Bel. “Thanks to the enormous flight of artificial intelligence over the last five years or so, information obtained by medical scans is converted into radiotherapy plans in just 15 to 20 minutes.”
Collaborations with partners in industry are of utmost importance to implement these latest technologies and obtain advanced software applications for further development in research and clinical settings. Notably, Professor Bel also invests in educating the next generation of medical physics professionals, teaching students at Amsterdam UMC locations on both sides of the Amstel river.
For more information, contact Prof. Arjan Bel.
Text by Henri van de Vrugt