Definition and Overview

Radiation delivery refers to any technique used to deliver radiation into the body as a form of therapy. It is called radiation therapy or radiotherapy treatment, and is commonly used in cancer treatment. It works by using high-energy radiation beams to destroy cancer cells, with the purpose of shrinking tumors. Radiotherapy treatments are performed using various radiation delivery techniques, some of which are internal and some external. While some use x-ray energy, other techniques use gamma rays and other charged particles. Each technique has its own benefits and risks, so radiotherapy specialists carefully assess each patient’s condition and case specifics to determine the most appropriate technique to use. During this process, they may perform various tests and scans, such as CT, MRI, and PET scans.

Who Should Undergo and Expected Results

What is radiation therapy?

Radiation therapy is primarily used as a form of cancer treatment. It is considered as the 8th element cancer cure, and is so prevalently used nowadays that around 50% of all cancer patients undergo the said procedure at some point during their treatment. In some cases, the purpose is palliative, which means the treatment aims to reduce the tumor’s size to help relieve the patient’s symptoms. In other cases, however, the purpose is to cure the patient by attempting to eliminate the tumor completely.

Thanks to modern developments in oncology, there are now many techniques used in radiation delivery. Prior to undergoing radiation treatment, patients undergo an assessment process wherein their oncologist decides on which radiation delivery method is most appropriate for them. The goal is to find the most optimal radiation delivery method given the patient’s specific circumstances, and to match this with the correct dosing strategy given the extent and size of the cancer. Dosing strategies refer mainly to how the radiation dose is delivered. It can be either hyperfractionated, which divides the dose into two treatment sessions per day over a course of several weeks, or hypofractionated, which delivers larger doses less than once a day. In some cases, doctors also use an accelerated radiation strategy wherein the total dose of radiation is delivered over a shorter period, i.e. 1-2 weeks. This means that patients get higher doses per session as well as more sessions, but the total length of treatment is shorter.

Its prevalent use in cancer treatment is due mainly to the high efficacy rating of the procedure. It is known to be effective in destroying cancer cells because it targets the cells’ DNA. It aims to destroy the DNA beyond repair, thus rendering the cancerous cells unable to divide and multiply. Eventually, the damaged cells die and are naturally eliminated by the body. This helps not only in killing cancer cells but also in preventing any regrowth or recurrence.

How is the Procedure Performed?

The following are different techniques of radiation delivery:

  • External beam radiation therapy. In an external beam radiation therapy, the radioactive material is delivered from the outside of the patient’s body using a machine called linear accelerator. This is an outpatient procedure performed over a period of 6 to 8 weeks. During each treatment session, the patient lies down on a table and the machine delivers radiation to the target area from multiple directions. Since this procedure often uses proton radiation, it is also sometimes called proton therapy or proton beam therapy.

  • Three-dimensional conformal radiation therapy. A variant of the external beam that uses a special instrument called 3D-CRT or three-dimensional conformal radiotherapy. This helps doctors to target the tumors better, and thus also allows them to deliver higher doses of radiation to improve treatment results.

  • Intensity modulated radiation therapy. This procedure allows doctors to vary the doses of radiation they deliver to different parts of the treatment site. It also allows them to increase the dose targeted to the central tumor cells and decrease the dose directed to the area that is near the healthy cells.

  • Image-guided radiation therapy. Another modern approach to radiotherapy, this technique allows doctors to target tumor cells more accurately. It even accounts for body positioning changes and documents the degree of accuracy. It is sometimes used in combination with 3D-CRT or intensity-modulated radiotherapy.

  • Stereotactic radiosurgery. This is an outpatient procedure that delivers high doses of radiation to brain tumors and other intracranial conditions. The treatment can be performed all at once or over a period of several weeks during which the total radiation dose is fractionated or broken down.

  • Extracranial stereotactic radiation delivery. This is a variant of stereotactic radiosurgery used on tumors in other parts of the body. It works by delivering potent doses of radiation to the tumor. This is most commonly used on cancers of the neck, spine, chest, abdomen, and pelvic area. It is also one of the more advanced technologies in radiotherapy that helps hit only the targeted cells so that healthy tissues will not be affected.

  • Electromagnetic-guided radiation therapy. This is an innovative technique wherein tiny electromagnetic transponders are implanted into the treatment area near the tumor site. The implants send out radio waves and, by doing so, guide the radiotherapy machines in aiming the radiation towards the treatment area. Since the treatment area may shrink in size and eventually shift, this technique is very effective in refocusing the target of treatment.

Possible Risks and Complications

Like other cancer treatments such as chemotherapy, radiation treatment can also affect healthy cells. Thus, the treatment also comes with some side effects, some of which may occur immediately during treatment while some could develop later on, sometimes months or years after the end of treatment.

The most common side effects of radiation therapy include:

  • Skin irritation

  • Hair loss

  • Damage to the salivary glands

  • Urinary problems

To minimize these side effects, radiation specialists keep track of the amount of radiation that a normal healthy tissue can receive without suffering any damage. This allows them to aim the radioactive material at specific cells and avoid damaging healthy cells.

Recent developments in radiation delivery, such as those previously mentioned, also led to improved targeting of cells, thus making sure that only cancer cells are destroyed.

References:

  • Friedman WA, Bova FJ, Buatti JM, Mendenhall WM. “Radiation delivery.” Linac Radiosurgery. http://link.springer.com/chapter/10.1007%2F978-1-4612-2176-0_8

  • “External beam radiation.” American Cancer Society. https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/radiation/science-behind-radiation-therapy/how-is-radiation-given-external-beam-radiation.html

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