Proton Therapy

A proton is a positively charged particle that is part of an atom, the basic unit of all chemical elements, such as hydrogen or oxygen.

Protons are a superior form of radiation therapy. Fundamentally, all tissues are made up of molecules with atoms as their building blocks. In the center of every atom is the nucleus. Orbiting the nucleus of the atom are negatively charged electrons.

When energized charged particles, such as protons or other forms of radiation, pass near orbiting electrons,

The positive charge of the protons attracts the negatively charged electrons, pulling them out of their orbits. This is called ionization; it changes the characteristics of the atom and consequentially the character of the molecule within which the atom resides. Because of ionization, the radiation damages molecules within the cells, especially the DNA or genetic material. Damaging the DNA destroys specific cell functions, particularly the ability to divide or proliferate. 

Cancerous cells are particularly vulnerable to attacks on DNA because of their high rate of division and their reduced abilities to repair DNA damage.

Proton therapy is particularly useful for treating cancer in children because it lessens the chance of harming healthy, developing tissue. Children may receive proton therapy for rare cancers of the central nervous system (brain and spinal cord) and the eye, such as retinoblastoma and orbital rhabdomyosarcoma.

As with other forms of external beam therapy, proton beam therapy requires a treatment team, including a radiation oncologist, radiation physicist, dosimetrist, radiation therapist, and nurse. The radiation oncologist is a specially trained physician who evaluates the patient and determines the appropriate therapy, specific area for treatment, and radiation dose. Working together, the radiation oncologist, radiation physicist, dosimetrist and radiation therapist establish the best way to deliver the prescribed dose. The radiation physicist and the dosimetrist make detailed treatment calculations to ensure treatment will be accurately delivered. Radiation therapists are specially trained technologists who perform the daily radiation treatments. Radiation therapy nurses are team members who tend to your day-to-day concerns and help to manage the side effects of the treatment.

Compared with standard radiation treatment such as x-ray, proton therapy has several benefits. It reduces the risk of radiation damage to healthy tissues; may allow a higher radiation dose to be directed at some types of tumors, which may keep the tumor from growing or spreading; and may result in fewer and less severe side effects (such as low blood counts, fatigue, and nausea) during and after treatment. However, Proton therapy costs more than conventional radiation therapy, and insurance providers have varying rules about which diagnoses are covered and how much patients need to pay. 

Comparison of proton therapy with X-ray therapy

                                       photo source:http://www.shi.co.jp/quantum/eng/product/proton/proton.html