A new quality control procedure for detecting defects in proton range modifiers for proton therapy

Proton beam radiotherapy is an increasingly common and accepted form of cancer treatment, which utilizes the novel energy-deposition characteristics of heavy, charged particles to destroy tumor cells. At the CDH Proton Therapy Center in Warrenville, IL, the main beam-delivery technique employs patient-specific beam modifiers to conform the beam to the target area, both perpendicular to the direction of beam travel and along the beam's axis. These devices are manufactured on-site using specifications generated by treatment planning software, and are subjected to several measurement and identification procedures to verify their integrity before use. A periodic manufacturing defect, not detected by this quality assurance procedure, was discovered by the author, and during the investigation to determine the root cause of the issue and whether the radiologic properties of the defects were relevant in clinical practice, a new quality assurance program was developed.