Dr. Tsubokura's Radiation Lecture Vol.129

Author: Masaharu Tsubokura M.D., PhD.

Editors: Akihiko Ozaki M.D., PhD., Yuki Senoo

257 Radiation therapy is also used to treat other diseases

　　　　Current cancer treatment consists of three standard therapies: surgery, anticancer drugs (chemotherapy), and radiation therapy. Treating cancer by irradiation of cancer cells is one option that is as effective as surgery or chemotherapy.

Radiation therapy is not only for cancer treatment, but also used to treat other benign diseases.

　For instance, Gamma Knife radiosurgery is a type of radiation therapy used to treat lesions (benign tumors) in the brain. In Gamma Knife radiosurgery, patients are outfitted with a helmet with hundreds of holes to focus the radiation beams on the target. Although Gamma Knife radiosurgery does not use an actual knife, it is named as such because it can treat brain lesions without craniotomy (removal of brain tissue). Gamma Knife radiosurgery's mechanism of action is similar to that of a magnifying glass that can focus scattered sunlight to a single point and burn the paper.

　Of course, the choice of treatment depends on the state, condition, and type of disease. The emergence of Gamma Knife radiosurgery has enabled treatment of benign brain tumors and morphological abnormalities (abnormality in shape) of blood vessels in the brain, as well as other lesions located in the deep part of the brain or areas responsible for vital functions, without risking the patients’ safety.

258 Radiation ingenuity to target cancer cells

Current cancer treatment consists of three standard therapies: surgery, anticancer drugs (chemotherapy), and radiation therapy. Treating cancer by irradiation of cancer cells is one option that is as effective as surgery or chemotherapy.

When x-rays, which are routinely used in everyday medical practice, are applied to our body from an external source, the nearby skin surface receives the highest amount of radiation exposure. In contrast, the tissues located deep inside of the body receive less radiation exposure. Therefore, when an x-ray with a high enough energy level to damage cancer cells located in the deep parts of the body is applied, the surrounding tissues in the surface area are subject to severe damage. In radiation therapy, various measures are taken to limit the radiation exposure to healthy tissues surrounding the cancer cells.

　In the process of radiation treatment planning, the size, shape, and location of the cancer cells and the surrounding normal tissues are measured precisely. Furthermore, the radiation-emitting device is designed to control and modify the application of radiation rays to match the shape of the cancer cells. Over time, there have been continual improvements to the technological aspect of radiotherapy to limit the amount of radiation exposure of normal, healthy tissues and focus damage on cancer cells alone by applying a low dose of radiation from many directions.

--------------------------------------------------------------------------------------------------------------------------------------------------------------

The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, 22nd and 29th December 2019 was reproduced for MRIC Global under the author's permission.