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In a patient’s journal, you might come across the abbreviation XRT. This stands for radiation therapy, also known as radiotherapy.
Radiation therapy is one of several types of treatment available for different types of cancer. It utilizes the destructive power of radiation to kill cancer cells. There are 2 main types depending on how the radiation is given, external beam radiation therapy and brachytherapy.
Continue reading below to get a short introduction to what radiation therapy is, how it works and how it is applied.
What is radiation therapy?
Radiation therapy is a type of cancer treatment. It utilizes high-energy radiation to kill cancerous cells in the human body.
The radiation used is typically X-rays, similar to the ones used to take x-ray pictures, but proton and other types of high energy radiation can also be used.
We typically separate between two types of radiation therapy. External beam radiation therapy and internal radiation therapy, also known as brachytherapy.
External beam radiation therapy
External beam radiation therapy utilizes what is known as a linear accelerator. This is a machine that is able to generate beams of radiation which is then directed towards the cancerous tumor.
The machine itself looks like a large X-ray machine, and the patient lies on a flat table just underneath.
In modern machines, each treatment is tailored to the individual patient. The beam is adjusted to affect as little, normal, healthy tissue as possible. Also, the machine can rotate around the patient to deliver the radiation from several angles.
With Brachytherapy, the source of the radiation is placed inside the patient’s body, as opposed to being directed from the outside.
The radiation source is usually placed within or next to the tumor. And can be permanent or temporary.
With permanent brachytherapy, small seeds filled with radioactive material are inserted directly into the tumor using a needle.
Permanent brachytherapy is common in the treatment of prostate cancer in men.
With temporary brachytherapy, a delivery device is placed inside or next to the tumor. This can be a catheter, needle, or probe, depending on the type of tumor and location.
The device then delivers high dose radiation for the duration of the treatment before it is removed.
Temporary brachytherapy is common in the treatment of cervical cancer in women.
How does radiation therapy work?
Every cell, including cancer cells, is dependent on its DNA to survive and divide. High energy radiation is harmful to all living cells as it can cause damage to the DNA.
In many cases, this damage can be repaired, however, if the radiation dose is high and/or repeated, it can cause irreversible damage.
In such cases, the cell will be unable to survive and/or divide, resulting in the death of the cell.
In radiation therapy, the aim is to direct high-energy radiation to the cancerous cell of a tumor, causing widespread death of the tumor cells.
Most often, one treatment is not enough, therefore, radiation therapy is usually given in several sessions over a given period of time.
When is radiotherapy used?
Radiation therapy can be used in the treatment of most types of cancer. However, the goal of the treatment can vary significantly.
Depending on the type, location, and stage of the tumor, as well as the patient’s age. Radiation therapy can be given with 4 primary treatment intents
In some cases, radiation therapy is given with curative intent. This means that the aim of the treatment is to kill all cancerous cells in order to make patients cancer-free.
Adjuvant radiation therapy is the process of giving radiation therapy after other primary cancer treatments, such as surgical removal, to reduce the chance of cancer returning (known as remission).
This is because all visible tumor tissue might have been removed, but small, microscopic pieces might remain.
Neoadjuvant radiation therapy is the process of giving radiation therapy before other primary cancer treatment. Most often this is before surgical removal of a tumor.
The reason for this is that radiation therapy can greatly reduce the size of the tumor, which makes surgical removal easier and reduces the chance of complications.
Also neoadjuvant therapy has shown to reduce the risk of cancer returning after surgical removal.
Palliative radiation therapy can be given In cases where the cancer is at such an advanced stage that curative treatment is not possible.
In such cases, giving radiation can shrink tumors and slow down its growth, which in turn can reduce or control the symptoms of the disease.
ACR, R. S. N. A. and. (2019, March 20). Introduction to Cancer Therapy (Radiation Oncology). Radiologyinfo.org. https://www.radiologyinfo.org/en/info/intro_onco.
ACR, R. S. N. A. and. (2019, October 7). Brachytherapy. Radiologyinfo.org. https://www.radiologyinfo.org/en/info/brachy.
Mayo Foundation for Medical Education and Research. (2020, July 1). Radiation therapy. Mayo Clinic. https://www.mayoclinic.org/tests-procedures/radiation-therapy/about/pac-20385162.