Radiation therapy has been in use as a cancer treatment for more than 100 years, with its earliest roots traced from the discovery of x-rays in 1895. The concept of therapeutic radiation was invented by German physicist Wilhelm Conrad Röntgen when he discovered that the x-ray was a powerful and effective tool with which to treat cancer.
The field of radiation therapy began to grow in the early 1900s largely due to the groundbreaking work of Nobel Prize-winning scientist Marie Curie, who discovered the radioactive elements polonium and radium. This began a new era in medical treatment and research. Radium was used in various forms until the mid-1900s when cobalt and caesium units came into use. Medical linear accelerators have been developed since the late 1940s.
With Godfrey Hounsfield’s discovery of computed tomography (CT), three-dimensional planning became a possibility and created a shift from 2-D to 3-D radiation delivery; physicians and physics were no longer limited because CT-based planning allowed physicians to directly measure the dose delivered to the patient's anatomy based on axial tomographical images. Orthovoltage and cobalt units have largely been replaced by megavoltage linear accelerators, useful for their penetrating energies and lack of physical radiation source.
In the last few decades, the advent of new imaging technologies, e.g., magnetic resonance imaging (MRI) in the 1970s and positron emission tomography (PET) in the 1980s, as well as new radiation delivery and visualization products, e.g., digital linear acceleratr, image fusion has moved radiation therapy from 3-D conformal to IMRT and eventually to IGRT (4-D) in the near future. These advances have resulted in better treatment outcomes and less side effects. Now 70% of cancer patients receive radiation therapy as part of their cancer treatment.
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