External Beam Radiotherapy: Physics’ Secret Weapon Against Cancer

Cancer is the biggest killer in Ireland, being responsible for around 30% of deaths every year. Therefore it’s of the utmost importance that we as physicists use our knowledge to combat this deadly disease. One of the most advanced ways physics is being used to fight cancer is in External Beam Radiotherapy (or XRT for short).  This non invasive treatment can be used for treating a wide variety of cancers such as brain tumors, lung cancer and breast cancer.

How this brilliant piece of technology works is quite fascinating. One of the most advanced types of XRT is Intensity Modulated Radiotherapy. This uses several linear accelerators placed at different angles to target cancer cells with immense precision. How a linear accelerator works is that it essentially speeds tiny particles up to very high speeds and uses these to produce x rays, which are shot at the cancer cell like bullets from a gun. When these rays hit the cancer cell they destroy it due to their high energy. If you were to shoot too many of these from the same angle, the healthy tissue that the “bullets” have to pass through would also get damaged. So by placing the accelerators at different angles we ensure that no one segment of healthy tissue gets too damaged, while the damage to the cancer cell is maximized. Each “gun” can also independently have its intensity modified. MRI’s and CT scans are typically used to perfect the dose size and intensity of the x rays.

After reading this I hope you can see the important contribution that physics makes to fighting cancer. Physics isn’t just about exploring space or making discoveries about miniscule pieces of matter that we can’t even see, it is often used to save lives.