Characterization of the microbunch time structure of proton pencil beams at a clinical treatment facility.

Characterization of the microbunch time structure of proton pencil beams at a clinical treatment facility.
Phys Med Biol. 2016 Mar 4;61(6):2432-2456
Authors: Petzoldt J, Roemer KE, Enghardt W, Fiedler F, Golnik C, Hueso-González F, Helmbrecht S, Kormoll T, Rohling H, Smeets J, Werner T, Pausch G
Abstract
Proton therapy is an advantageous treatment modality compared to conventional radiotherapy. In contrast to photons, charged particles have a finite range and can thus spare organs at risk. Additionally, the increased ionization density in the so-called Bragg peak close to the particle range can be utilized for maximum dose deposition in the tumour volume. Unfortunately, the accuracy of the therapy can be affected by range uncertainties, which have to be covered by additional safety margins around the treatment volume. A real-time range and dose verification is therefore highly desired and would be key to exploit the major advantages of proton therapy. Prompt gamma rays, produced in nuclear reactions between projectile and target nuclei, can be used to measure the proton's range. The prompt gamma-ray timing (PGT) method aims at obtaining this information by determining the gamma-ray emission time along the proton path using a conventional time-of-flight detector setup. First tests at a clinical accelerator have shown the feasibility to observe range shifts of about 5 mm at clinically relevant doses. However, PGT spectra are smeared...

Source: Medical Physics - March 4, 2016 Category: Physics Authors: Petzoldt J, Roemer KE, Enghardt W, Fiedler F, Golnik C, Hueso-González F, Helmbrecht S, Kormoll T, Rohling H, Smeets J, Werner T, Pausch G Tags: Phys Med Biol Source Type: research