What are the goals of Radiation Therapy


Simple put, the goal of  radiation therapy is to cure cancer!


This might come as a surprise to you. Radiotherapy can cure cancer. And generally this is the goal of radiotherapy, but there are times when radiation therapy is used for other purposes. There are four goals of radiation therapy, which depend on the condition the patient is in, and what state the cancer has progressed to; they are


  • To shrink and cure early stage cancers
  • To stop cancer from recurring
  • To treat the symptoms of advanced staged cancers
  • Alternative treatments


Radiotherapy is generally considered a local treatment. This is because the radiation is aimed at specific targets inside the body. The target is where the tumor is and a small area around the tumor for any microscopic spread into the healthy surrounding tissue.


As a radiation beam passes through the body it deposits dose along the entire path of the beam. To ensure the dose delivered to the target is enough to achieve the goal of radiotherapy it generally cannot be delivered only from one direction.  This is because the dose before and after the target will be much too high for the surrounding tissue. This extra dose to the healthy tissue is what can lead to undesirable side effects.


Take a look at the image blow. It shows computer simulation of a single beam delivering dose to a test object. This test object is a mock simulation of a chest, with two lungs and the spin. There is also a pink target volume (tumor) drawn in the middle. The dose is coloured from red to blue. Red representing the high dose, and blue representing low dose. You can see when using one beam to target the pink imaginary tumor that all the high dose (red) is near the surface. The pink target gets dose in the middle range (green).


radiotherapy goals

Simulation of a Single Beam of Radiation aimed the pink target. Red is high dose and blue is low does. The high dose region is outside the volume of the pink target- This is not idea.


To increase the dose delivered to the target and not to the healthy tissue surrounding the target like the image above you can add more radiation beams from different angles. This allows a lower dose  (blue) to be delivered to surrounding healthy tissue, while the pink target receives higher does (red). This is demonstrated in the following computer simulation below.  You can also see how the high dose is conformed around the pink target, while the healthy tissue around receives lower dose when compared to the first simulation.


goals of radiotherapy

Simulation of multiple Beams of Radiation aimed the pink target. Red is high dose and blue is low does. The high dose red region is closely surrounding the pink target volume. This is an ideal situation.


This brings us to the main principle of radiotherapy, and the goal of radiation protection. The goal being ALARA- as low as reasonably achievable. In radiation protection this means that the dose that someone will receive from a radiation producing machine or radioactive material is as low as reasonably achievable.


Obviously in radiotherapy there is going to be some radiation exposure. This is needed to kill the cancer, otherwise no benefit is received at all. The way that ALARA is applied in radiation therapy is to minimize the dose to the healthy tissue around the tumor to be as low as reasonably achievable. This is done by using several different techniques; like having a number of different beams pointing at the tumor from different directions as shown in the above images.


Maximize Radiation Dose to the Tumor


Radiation therapy tries to maximize the dose delivered to the abnormal tumor cells, while minimizing the dose received by the normal healthy tissue surround it. This is the radiation protection principle of ALARA. Using this method minimizes any chance of side effects occurring, while achieving one of the goals.


1. To cure, shrink, and destroy early stage cancers


Cancers is generally more sensitive to radiation than healthy tissue. This is great. It means that radiation can be used to destroy and shrink tumors, and hopefully cure cancer. Radiation treatments with the goal of curing cancer can be delivered alone, or a few cycles of chemotherapy can be given before hand. Sometimes it is done after surgery as well. This is to help prevent any cancer accidentally left behind from coming back.


Certain chemotherapy drugs can also make the radiation work better as they are radiosensitizers. Radiosensitizers make the cancer cells even more sensitive to radiation. A lower dose of radiation is then needed to kill the cancer cells. This means that a lower dose will be delivered to the healthy tissue in the area. A win-win situation.


Radiation Therapy and the other forms of cancer treatments, like chemotherapy and surgery, are planned by several doctors including surgeons, medical oncologists, and radiation oncologists, as well as the patient. Every patient’s situation will be will be assessed to insure the course of action is taken.


2. To stop cancer from coming back somewhere else


Radiation therapy can be used to stop cancer from coming back somewhere else. When there is a risk of a spread of the cancer from a different the area may be treated with radiation to insure that the cancer doesn’t spread. Often there will be no sign of a tumor on a CT or MRI image, but certain cancers are known to spread in certain ways.


For instance, lung cancer is know to spread to the brain. So some lung cancer patients will have preventive radiation to the head to try and prevent any new tumors from forming in the brain.  Although preventive radiation treatment is not as common as it once was. This is because it may be better just to have regular checkups and screenings to check if there has been spread, rather than irradiating more of the patient.


3. Symptom treatment caused by advanced cancer


Unfortunately some patients don’t read the signs of cancer early enough. (so go to the doctor if you are concerned! seriously) The cancer can then be too far spread and out of control to be cured.  But, these tumors can still be treated in the hopes to shrink the tumor. This can make the person feel better and can relieve some symptoms such as pain, trouble breathing and the like. This type of treatment is called palliative radiation therapy.


4. Alternative treatments


There are some alternative radiation treatments out there. We’re not talking about alternative medicine, alternative treatments that have scientific backing. One of the most common one is the treatment of keloid scars.


A keloid is an overgrown of a scar tissue after a wound has healed. Radiation can be used to effectively break down the keloid. The goal of this is to stop the keloid from growing back. This treatment has been around for a long time. In fact it has been a common treatment for over a century.




The goal of radiation therapy is to use radiation to shrink and cure early stage cancer, to stop any cancer from spreading and to treated late stage cancer. There are some alternative treatments that radiation can be used for.


Remember, the information here is should not be considered as medical advice and is not intended to replace you going to see your doctor!