Proton Therapy

Overview of Proton Therapy in India

Proton therapy is a type of radiation therapy; radiation therapy is a way to use a lot of energy (high-energy) to be able to give treatment for cancerous and non-cancerous tumors. Traditionally, X-ray radiation therapy has been the primary means of treating these types of tumor. Proton therapy is a newer way of treating tumor using energy from positively charged particles called protons.

In order to apply damage to the cancers, proton therapy uses energy beams to shine (aim) energy at the body. Energy from the proton beams shines through the tissue, damaging the molecular (DNA) of those cells. When the cells are damaged, they have the ability to repair themselves. Healthy cells have a greater ability than cancer cells to repair their damage. Therefore, the damaged cancer cells cannot continue to grow or reproduce.

Proton therapy has proven to be an effective treatment for some cancer types. Whether proton therapy has fewer side effects than traditional radiation therapy is still difficult to say as there have not been many studies that compare the effects of proton versus traditional radiation over an extended period of time, therefore whether proton therapy is more effective for long-term survival than traditional radiation.

What is Proton Therapy?

Proton therapy is a type of radiotherapy often referred to as "proton beam therapy." It can be used to treat both malignant and non-malignant neoplasms (tumors) by delivering a high-energy proton beam (radiation) specifically at the tumor and destroying the cancer cells' DNA, thus preventing growth and/or division.

One of the biggest advantages of using proton therapy over conventional radiation therapy is the precise control oncology physicians have over where they deliver their radiation treatment. With conventional radiation therapy, the radiation continues to travel through the body, whereas proton therapy delivers the radiation (proton beam) only in a very specific area (tumor) and limits any unnecessary radiation exposure to normal organs surrounding the tumor site.

The Bragg Peak phenomenon is what gives oncologists the ability to deliver the highest amount of energy to the tumor while causing minimal damage to the normal tissue surrounding the tumor.

Types of Proton Therapy:

Proton Therapy is not an identical treatment type; there are multiple treatment types that have been developed for optimal accuracy and effectiveness:

Passive scattering proton therapy

Passive scattering proton therapy is the traditional way of administering protons to a tumor by spreading a proton beam across the entire tumor volume. This technique is efficacious, but not as accurate as newer technologies.

Pencil beam scanning (PBS)

Pencil beam scanning is an advanced technique that directs a narrow proton beam to paint the tumor layer by layer. PBS treatment provides for more accurate targeting of tumors and helps to minimise radiation dose delivered to adjacent organs and tissues.

Intensity Modulated Proton Therapy (IMPT)

Intensity modulated proton therapy is an advanced version of PBS in which the intensity of the proton beam is spatially modulated throughout the tumor.

Procedure:

Imaging

To​‍​‌‍​‍‌​‍​‌‍​‍‌ pinpoint the tumor's location and size, you will undergo imaging tests such as a CT scan or MRI.

These scans allow the radiation oncologist to identify the tumor and use a computer to not only delineate its exact shape and size but also map out the important surrounding organs and tissues.

Simulation

The recruitment of imaging data does not stop there; it is also used for handling your body prepping for the treatment. The care team may identify the points on your body for directing the proton beam. These points are minimal and are mostly short-term; however, some can be long-term. After the perfect position is found, a staff member will make you an immobilisation device to ensure that you can stay in the same position during each treatment. When a part of your head or neck is treated, the team will make a custom mesh mask fitted to your face to prevent your head from moving. You will still be able to see through and breathe while wearing the mask.

Dose planning

The radiation oncologist will decide the precise quantity of radiation that should be administered to the target area. Using specialised computer programs, dosimetrists plan the optimal way to deliver a certain dose, the beam orientation and the depth of the beam in the body.

Quality assurance

Physicists make a quality control confirmation that the beam can be produced to the exact needed dose, treatment depth and ​‍​‌‍​‍‌​‍​‌‍​‍‌angles.

What Happens During Proton Beam Treatment?

A proton therapy treatment is done as an outpatient procedure at a specialised facility. Usually, proton therapy requires several treatment sessions, with some types of treatment taking longer than others. The proton treatment itself is performed in a dedicated room, using a large mechanical arm (gantry) that moves the proton beam around the patient while lying on the treatment table.

While​‍​‌‍​‍‌​‍​‌‍​‍‌ you are undergoing a proton therapy treatment:

Your care team will get you ready on the treatment table there as they did during the simulation session. To keep your head and body still, they will use positioning devices, for instance, a body mould or a mask.

The radiation oncologist will set the equipment so that the proton beam enters through the marks on your skin that correspond to the tumor location. The equipment is not a small enclosed space like an MRI machine, so you are not supposed to feel claustrophobic during treatment, but you will have to keep very still.

To make sure you are at the right spot and everything is in the right position, an X-ray or other scan will be taken.

The radiation therapists will go out of the room to run the proton beam machine. They can see and hear you through a video camera, so you will not be really alone.

When the machine is running, the particle accelerator located in a different room shoots protons at high speed, which then get directed to the gantry in the treatment room. The gantry makes the protons into a very thin beam and aims this beam at the tumor. It may be the case that the gantry moves around your body to be able to treat the tumor from different angles.

During the time treatment goes on, the proton beam is likely to be switched on and off several times, as it moves or has to be realigned with the tumor in case of a breath-induced shift. The proton beam entering the body or treating the tumor is imperceptible to you, but the machine moving around you may produce the clicking sounds that you will ​‍​‌‍​‍‌​‍​‌‍​‍‌hear.

How Long Do Proton Therapy Treatments Take?

Your length of stay may vary based on diagnostic imaging findings resulting from size, location and number of tumors; however, you can generally expect to be in the treatment room for approximately 15-30 minutes. Proton radiation treatment lasts only a few minutes, but you will also need to be positioned accordingly, with the machine calibrated to produce a proton beam, which will require additional time. A full appointment may last over an hour, from the moment of entry until the time to leave.