Proton therapy

An advanced type of radiation therapy using protons to treat cancer

A proton therapy machine at the Mayo Clinic.

Comparison of dose profiles for proton versus x-ray radiotherapy.

Comparison of dose distributions between Intensity-Modulated Proton Therapy (IMPT) and Intensity-Modulated Radiation Therapy (IMRT).

Proton therapy, also known as proton beam therapy, is a type of radiation therapy that uses protons rather than x-rays to treat cancer. It is a form of particle therapy that uses a beam of protons to irradiate diseased tissue, most often in the treatment of cancer. The main advantage of proton therapy over other types of external beam radiotherapy is that as a charged particle, the dose of protons can be controlled more precisely, allowing for a higher dose of radiation to be delivered to the tumor while minimizing damage to surrounding healthy tissue.

Principles of Proton Therapy

Proton therapy takes advantage of the unique physical properties of protons. Unlike x-rays, which deposit energy along their entire path through the body, protons have a distinct advantage known as the Bragg peak. This is a phenomenon where protons deposit the majority of their energy at a specific depth, which can be controlled by adjusting the energy of the proton beam. This allows for the delivery of high doses of radiation to the tumor with minimal exposure to surrounding healthy tissues.

Clinical Applications

Proton therapy is particularly beneficial for treating tumors that are located near critical structures, such as the brain, spine, or eyes, where conventional radiation therapy might pose a risk of damage to these sensitive areas. It is also used in pediatric oncology, where minimizing radiation exposure to healthy tissue is crucial to prevent long-term side effects.

Advantages and Disadvantages

Advantages

• Precision: Proton therapy allows for precise targeting of tumors, reducing the risk of damage to surrounding healthy tissues.
• Reduced Side Effects: Due to its precision, patients often experience fewer side effects compared to conventional radiation therapy.
• Pediatric Use: Particularly beneficial for children, as it reduces the risk of developmental issues associated with radiation exposure.

Disadvantages

• Cost: Proton therapy is more expensive than conventional radiation therapy due to the complexity and cost of the equipment required.
• Availability: There are fewer proton therapy centers compared to conventional radiation therapy facilities, which can limit access for some patients.

History and Development

The concept of using protons for medical treatment was first proposed by Robert R. Wilson in 1946. The first treatments were conducted in the 1950s and 1960s at research facilities, but it wasn't until the 1990s that proton therapy centers began to be established for clinical use.

Current Research and Future Directions

Research is ongoing to improve the delivery and effectiveness of proton therapy. Advances in imaging and treatment planning are enhancing the precision of proton therapy. Additionally, studies are being conducted to compare the outcomes of proton therapy with other forms of radiation therapy, such as Intensity-Modulated Radiation Therapy (IMRT).

Also see

• Radiation therapy
• Particle therapy
• Intensity-Modulated Radiation Therapy
• Bragg peak