PET-based dose delivery verification in proton therapy: a GATE based simulation study of five PET system designs in clinical conditions

Phys Med Biol. 2013 Oct 7;58(19):6867-85. doi: 10.1088/0031-9155/58/19/6867. Epub 2013 Sep 12.


PET is a promising technique for in vivo treatment verification in hadrontherapy. Three main PET geometries dedicated to in-beam treatment monitoring have been proposed in the literature: the dual-head PET geometry, the OpenPET geometry and the slanted-closed ring geometry. The aim of this work is to characterize the performance of two of these dedicated PET detectors in realistic clinical conditions. Several configurations of the dual-head PET and OpenPET systems were simulated using GATE v6.2. For the dual-head configuration, two aperture angles (15° and 45°) were studied. For the OpenPET system, two gaps between rings were investigated (110 and 160 mm). A full-ring PET system was also simulated as a reference. After preliminary evaluation of the sensitivity and spatial resolution using a Derenzo phantom, a real small-field head and neck treatment plan was simulated, with and without introducing patient displacements. No wash-out was taken into account. 3D maps of the annihilation photon locations were deduced from the PET data acquired right after the treatment session (5 min acquisition) using a dedicated OS-EM reconstruction algorithm. Detection sensitivity at the center of the field-of-view (FOV) varied from 5.2% (45° dual-head system) to 7.0% (full-ring PET). The dual-head systems had a more uniform efficiency within the FOV than the OpenPET systems. The spatial resolution strongly depended on the location within the FOV for the ϕ = 45° dual-head system and for the two OpenPET systems. All investigated architectures identified the magnitude of mispositioning introduced in the simulations within a 1.5 mm accuracy. The variability on the estimated mispositionings was less than 2 mm for all PET systems.

MeSH terms

  • Head and Neck Neoplasms / diagnostic imaging
  • Head and Neck Neoplasms / radiotherapy
  • Humans
  • Image Processing, Computer-Assisted
  • Male
  • Monte Carlo Method*
  • Positron-Emission Tomography*
  • Prostatic Neoplasms / diagnostic imaging
  • Prostatic Neoplasms / radiotherapy
  • Proton Therapy / methods*
  • Radiation Dosage*
  • Radiotherapy Dosage
  • Radiotherapy Planning, Computer-Assisted
  • Radiotherapy, Image-Guided / methods*