continued Children with leukemia typically get chemotherapy only, but children with other kinds of cancer, including brain tumors and other solid tumors, are also treated with radiation therapy.
“Radiation is considered local control, whereas chemotherapy is systemic. Radiation is localized,” Kerr said. “It’s targeted directly to the site of certain types of cancer, which is why it is rarely used in leukemia, which is more of a systemic cancer. It’s used for children with isolated lymphomas or brain tumors.”
Radiation was discovered by German physics professor Wilhelm Conrad Roentgen in 1896. Within three years, it was being used to treat cancer as it was discovered that it could greatly improve the patient’s chance for a cure.
Physicians had to be careful when using radiation in those early days, because it could also cause cancer. Many early radiologists used the skin of their arms to test the strength of radiation from their radiotherapy machines, looking for a dose that would produce a sunburn-like pink reaction. This was considered an estimate of the proper daily fraction of radiation. However, many of those doctors developed leukemia.
Since then, radiation therapy has become more precise, targeting tumors without harming the cells around them. According to the American Cancer Society, there are several types of therapy used in cancer patients: Conformal radiation therapy (CRT) uses CT images and special computers to very precisely map the location of a cancer in three dimensions. The patient is fitted with a plastic mold or cast to keep the body part still and in the same position for each treatment. The radiation beams are matched to the shape of the tumor and delivered to the tumor from several directions. Intensity-modulated radiation therapy (IMRT) is like CRT, but along with aiming photon beams from several directions, the intensity (strength) of the beams can be adjusted. This gives even more control over decreasing the radiation reaching normal tissue while delivering a high dose to the cancer. Conformal proton beam radiation therapy uses proton beams that cause little damage to tissues they pass through but effectively kill cells at the end of their path. Radiation can also be used at the time of surgery directly on nearby tissues after a tumor has been removed. In many cases, patients are dosed with so-called radiosensitizers that make cancer more sensitive to radiation.