Dr. Tsubokura's Radiation Lecture Vol.70
Author: Masaharu Tsubokura
Editors: Akihiko Ozaki M.D., Yuki Senoo
139. Cancer benefits from both internal and external radiation therapies
Today, surgery, chemotherapy, and radiation therapy constitute a standard of cancer therapy. Radiation therapy is a procedure that exposes cancer cells to radiation, and it has been proved to be no less effective than surgery or chemotherapy.
We have previously explained that radiation exposure can be categorized into either external or internal radiation exposure. External radiation exposure occurs when your body is exposed to radiation from an external source (e.g., X-rays and CT scan). In contrast, internal radiation exposure occurs when your body is exposed to radiation from sources inside the body.
Similarly, radiation therapies are categorized corresponding to external and internal radiation exposures. The former is a method that delivers the radiation from an external source to cancer cells. In contrast, the latter is a method in which radiation sources are placed inside or next to the lesions requiring the treatment. In this method, radioactive substances contained in small cases can be directly placed inside the body, while in other cases, patients take radioactive substances through capsules or injections. These therapies are used to treat various types of cancer, including prostate cancer, uterine cancer, thyroid cancer, and cancer metastasis to bone.
140. Radiation therapy techniques to prevent damage to normal tissue
Today, surgery, chemotherapy, and radiation therapy constitute a standard of cancer therapy. Radiation therapy is a procedure that exposes cancer cells to radiation, and it has been proved to be no less effective than surgery or chemotherapy.
Several techniques for radiation therapy have been developed to protect the normal surrounding tissues from radiation damage as much as possible.
For example, in radiation therapy for breast cancer, when cancer lesions are exposed to radiation from the front to the back of the patient’s body, other normal organs, such as the skin, lungs, and heart, will be also exposed to the high dose of radiation. To avoid unnecessary exposure, a method called "tangential irradiation technique" is incorporated into the breast cancer treatment. In this method, a beam of radiation is delivered from the lateral side of the patient's body to irradiate only the cancer lesions.
In addition, in radiation therapy for prostate cancer, which tends to be located deep inside the body, various intensities of radiation are delivered to cancer lesions from different angles. This helps protect the rectum and bladder from radiation damage, as well as concentrate the radiation to the cancer lesions in the prostate.
The above-mentioned radiation therapy techniques have been developed to treat cancer effectively while minimizing the adverse side effects.
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The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, on 10th and 17th September 2017 was reproduced for MRIC Global under the author's permission.