Brief History of Radiation TherapyBrief History of Radiation Therapy
The Radiation Therapy (also known as radiotherapy and radiation oncology) field began shortly after the discovery of X-rays in 1895 by Wilhelm Rontgen. Physicians quickly began to use X-rays to diagnose broken bones and locate foreign objects in bodies. The following year, in 1896, Antoine-Henri Becquerel discovered that certain elements spontaneously emitted rays or subatomic particles from matter, a property which came to be known as radioactivity. Building on the work of Becquerel, Pierre and Marie Curie discovered the radioactive elements polonium and radium. While experimenting, they noticed that radium killed diseased cells -- the first indication that radiation could aid not just in the diagnosis of disease, but also in treatment.i
Largely due to the groundbreaking work of Nobel Prize-winning scientists Antoine-Henri Becquerel, Marie Curie and Pierre Curie, the field of radiation therapy grew quickly in the early 1900s.ii A new era in medical treatment and research began. In the early days of the field, physicians simply applied exposure to radiation in experiments and based their clinical practice on the observations. Although unaware of the mechanism of action, doctors reported cases of the control or regression of cancers due to radiation exposure.iii Although there was optimism regarding the potential medical benefits, there was also recognition that radiation could be harmful if inappropriately applied.
World War I was the first major world event in which 'roentgenology' played a role.iv Radiologic equipment was used in field hospitals during the war. French and American soldiers were trained to take X-rays, becoming perhaps the first x-ray technicians. Proven in combat, the demand for radiologic service and technology continued to grow. Many physicians sought to purchase X-ray machines for their offices, and a few even specialized as radiologists.v
Between World Wars I and II, physicists and biologists continued to discover how radiation works and how to measure the dose accurately. Physicists, electrical engineers, mining companies and commercial vendors continued to develop and market higher energy X-ray machines and new radium devices.vii
Although promising as a therapeutic modality, an important limitation of the early X-ray machines was their inability to produce high energy, deeply penetrating beams. Therefore, it was difficult to treat deep-seated tumors without excessive skin reactions.viii In the 1960s, high energy (megavoltage) treatment machines, known as linear accelerators or linacs, were introduced. Linacs were capable of producing high energy, deeply penetrating beams, allowing for the very first time treatment of tumors deep inside the body without excessive damage to the overlying skin and other normal tissues.ix
In the 1970s and 1980s, computers began to be used for planning treatment. The advent of new imaging technologies, including magnetic resonance imaging (MRI) in the 1970s and position emission tomography (PET) in the 1980s, has moved radiation therapy from 3-D conformal to intensity-modulated radiation therapy (IMRT) and image-guided radiation therapy (IGRT). IMRT uses radiation beams with different intensities to deliver different doses of radiation at the same time. The technology allows for the delivery of higher doses of radiation within the tumor and lower doses to nearby healthy tissue. IGRT is used in areas of the body that are prone to movements. Since tumors can actually move between treatments, this technology allows the radiation oncologist to image the tumor immediately before and during the treatment. Adjustments are made to the patient’s position and the radiation is more precisely aimed to target the tumor.
These advances have allowed radiation oncologists to better see and target tumors, which have resulted in better treatment outcomes, more organ preservation and fewer side effects.x
Radiation therapy is the single most effective cancer-treating agent. Today, more than 1/2 of all cancer patients receive radiation therapy during their illness.xi
i From Roentgen to radiation Therapy: A Tumultuous History, Advance for Imaging and Radiation Oncology, November 29, 1999.