Radiation Oncology: understanding different treatment plans

Cancer can be one of more complicated and difficult diseases people experience, and, while we may not have developed the perfect cancer treatment yet, cancer treatment has reached very advanced levels in accordance to the levels of complication with cancer.

One of the more common and effective ways to treat cancer is with radiation therapy.

The radiation used in treating cancer is ionizing radiation since it forms ions in the cells that the radiation passes though. Ions are electrically charged particles, so the radiation creates ions by removing electrons from the atoms and molecules inside the cells, which ends up killing the cells or altering the genes in a way that causes the cells to stop growing.

Although every radiation treatment uses ionizing radiation, it is important to remember that there are many different types of radiation treatments. The differences result from the different machinery, tools, execution, and techniques used when performing the therapy.

The differences between the different treatments are very significant as they lead to different energy levels in the radiation, which dictates have deeply and strongly the radiation will penetrate into the body’s tissues.

It is very important to have an idea what the different radiation treatments are because when it comes to planning a treatment, the radiation oncologist will work with you or your loved one to determine which type of radiation plan will be most suitable for your specific circumstances. So, here’s a quick guide to the various radiation treatments:

External Beam Radiations 

External-beam radiation therapy is typically delivered using a machine called a linear accelerator (or a LINAC). By using electricity to form a stream of fast-moving subatomic particles, a LINAC creates high-energy radiation, which treats the cancer.

3D-CRT: 3-dimensional conformal radiation therapy, or 3D-CRT, utilizes highly-advanced computer software and treatment machines that allows doctors to deliver radiation more effectively by targeting areas that conform to very precisely formed shapes.

IMRT: Intensity-modulated radiation therapy, commonly known as IMRT, utilizes hundreds of collimators (tiny radiation beam-shaping tools) to deliver a single dose of radiation. IMRT specifically allows the doctors to modulate how high the level of radiation is being delivered to specific areas and then determining how many doses to use for each specific spot.

IGRT: Image-guided radiation therapy, or IGRT, utilizes repeated imaging scans, such as MRIs and CT scans, so the doctors can identify changes in the tumor’s size and location. This allows them to adjust the patient’s position, the radiation doses, and the duration of the treatment accordingly, which increases the precision of the treatment.

Tomotherapy: Tomotherapy is sort of a hybrid between IMRT and IGRT as the machine both delivers radiation, as an external-beam radiation therapy machine would, and also provides images of the patient’s tumor immediately before treatment. This increases the precision of the radiation and spares more normal tissue.

Stereotactic Radiosurgery: Stereotactic radiosurgery, or SRS, delivers one or more very high doses of radiation to a small tumor by utilizing extremely accurate image-guided targeting techniques and strategic patient positioning. However, to avoid causing excess damage to surrounding healthy tissue, SRS can only be used to treat small tumors with very well-defined edges.

Stereotactic Body Radiation Therapy: Stereotactic body radiation therapy, or SBRT, delivers its radiation therapy in fewer sessions than other treatments typically do. SBRT uses smaller radiation fields with much higher doses than treatments such as 3D-CRT. Again, SBRT is only used to treat small, isolated tumors, such as cancers in the lung and liver. Doctors usually refer to SBRT systems by their brand names, which is most commonly the CyberKnife.

Proton Therapy: While the previous radiation therapies utilized photon beams, this treatment uses proton beams to deliver charged particles to the cancerous area. While photon beam radiation deposits its energy semi-evenly along its way through tissue, proton beams deposit much of their energy at the end of their path and deposit less along the way. This hypothetically decreases the amount of radiation being exposed to healthy tissue and increases the amount of radiation being exposed directly to the cancer.

Other Forms of Radiations

Internal Beam Radiation (Brachytherapy): Brachytherapy differs from the external beam radiation treatments as it utilizes radiation from a radiation source being placed inside or on the body. The sources usually involve radioactive isotopes being sealed in tiny pellets or seeds, which are then placed in patients using tools such as needles, catheters, and other forms of delivery techniques. Then, the isotope naturally breaks down, which results in the release of radiation that likely damages nearby cancer cells.

System Radiation Therapy: System radiation therapy involves the intake or injection of a radioactive substances, such as radioactive iodine or a radioactive substance bound to a monoclonal antibody. The iodine is used in cases with thyroid cancer as the thyroid naturally takes in the iodine substance, and other cases use the substance bound to the monoclonal antibody as the antibody naturally travels to and targets the infected cells where the tumor is located.

At the end of the day, there are many, many different ways to treat cancer. So, when it comes to planning your treatment, you can prepare yourself or your loved ones by just becoming familiar with some of the different treatments and how they work, that way you can be on the same page with your radiation oncologist. Also, always remember that while all of this information can be overwhelming, you can always ask someone on your radiology team or your health care provider any questions you may have, as they can likely provide you with the right answer. 

By Russell McBurnie

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