It only takes a few minutes for patients to receive their daily proton therapy treatment. However, for each treatment course, there have been hours of prior planning to develop the best treatment plan according to the radiation oncologist’s prescription. Medical dosimetry plays a vital role in proton therapy, helping to create a unique treatment plan comprising of the exact dose, beam angles, and patient positioning aspects required to deliver the appropriate dose volume to the target.
Protons are positively charged particles that have a unique range of penetration into the patient’s body. This is characterized by the Bragg Peak. The Bragg Peak occurs at the point where the highest dose of radiation is delivered to the patient’s body. Dosimetrists use physics software tools to determine how to formulate the proton beam energy and intensity in order for the Bragg Peak to occur precisely at the tumor site. With protons, there is minimal entrance dose and no exit dose. The Bragg Peak happens at the tumor because the protons can be controlled to stop at a specific depth. That’s what makes proton beam therapy so precise.
The dosimetry team works closely with medical physicists and radiation oncologists to determine the exact physics behind every single proton beam received by patients. No two treatment plans are the same. Treatments are completely customized based on the individual’s tumor, body, and other factors.
One of the most important goals for a dosimetry team is to find the best treatment plan for every individual patient, with the objective of minimizing radiation to healthy tissue and vital organs. Some proton centers do this using pencil beam scanning technology, where the beam of radiation is just millimeters wide. The beam’s position and depth can be controlled to bypass nearby organs and target the tumor directly. The precision of pencil beam scanning, in conjunction with the dosimetrists’ proton therapy treatment plan, ensures that patients receive less radiation outside the target areas. This reduces side effects and helps to maintain the patient’s quality of life during and after treatment.
Medical Dosimetry and Medical Physics teams are dedicated to ensuring each proton therapy patient receives the best treatment plan possible, based on his or her prescribed radiation dose from the radiation oncologist.