Proton-Based Stereotactic Ablative Radiotherapy in Early-Stage Non-Small-Cell Lung Cancer
Figure 1
Demonstration of the Bragg peak that is characteristic of proton therapy. Individual proton beam energies are represented by the multiple red curves, with higher energies depositing their maximum energy at an increased depth. The summation of these individual beams is represented by the blue curve, known as the spread-out Bragg peak (SOBP). This SOBP is calculated and delivered such that the full depth of the target receives this maximum radiation dose. The sharp falloff following the Bragg peak allows tissues distal to the target to be spared. The green curve represents the dose deposition profile of X-ray therapy. In contrast to proton therapy, the maximum dose is deposited within several centimeters of tissue penetration and distal tissues receive a gradually decreasing amount of radiation exposure.