Full-beam performances of a PET detector with synchrotron therapeutic proton beams

Abstract

Treatment quality assessment is a crucial feature for both present and next-generation ion therapy facilities. Several approaches are being explored, based on prompt radiation emission or on PET signals by [Formula: see text]-decaying isotopes generated by beam interactions with the body. In-beam PET monitoring at synchrotron-based ion therapy facilities has already been performed, either based on inter-spill data only, to avoid the influence of the prompt radiation, or including both in-spill and inter-spill data. However, the PET images either suffer of poor statistics (inter-spill) or are more influenced by the background induced by prompt radiation (in-spill). Both those problems are expected to worsen for accelerators with improved duty cycle where the inter-spill interval is reduced to shorten the treatment time. With the aim of assessing the detector performance and developing techniques for background reduction, a test of an in-beam PET detector prototype was performed at the CNAO synchrotron-based ion therapy facility in full-beam acquisition modality. Data taken with proton beams impinging on PMMA phantoms showed the system acquisition capability and the resulting activity distribution, separately reconstructed for the in-spill and the inter-spill data. The coincidence time resolution for in-spill and inter-spill data shows a good agreement, with a slight deterioration during the spill. The data selection technique allows the identification and rejection of most of the background originated during the beam delivery. The activity range difference between two different proton beam energies (68 and 72 MeV) was measured and found to be in sub-millimeter agreement with the expected result. However, a slightly longer (2 mm) absolute profile length is obtained for in-spill data when compared to inter-spill data.

New Digital Plug and Imaging Sensor for a Proton Therapy Monitoring System Based on Positron Emission Tomography

“…This prototype allowed a measurement of the fast decay of 12 N, which has an half-life of just 11 ms, during the proton irradiation, increasing the rejection of the prompt photon background and consequently improving the image quality. SiPMs (MPPC; HAMAMATSU) are also currently used in the prototype of the INSIDE PET scanner, for the readout of Lutetium Fine Silicate (LFS) crystals with size mm 3 composing the cm 2 PET panels [ 37 , 38 ].…”

An overview of recent developments in FLUKA PET tools

“…The high customization cost of such solutions is one of the main reasons which limits the clinical use of PET in vivo range verification with charged particles to offline images obtained a posteriori [36,37,31]. The development of dedicated dual-head PET scanners such as BASTEI [38,39] has shown the feasibility of online PET [40,35], and in addition more recent experimental data acquired with DOPET [41] and INSIDE [42,43] in beam PET detectors, have demonstrated the possibility to introduce this technique in the clinical routine.…”

Use of short-lived positron emitters for in-beam and real-time β+ range monitoring in proton therapy

“…Assembly of the INSIDE in-beam PET scanner was completed in January 2016 and subsequently installed at the Centro Nazionale di Adroterapia Oncologica (CNAO) facility located in Pavia (Italy), a synchrotron-based facility treating patients since September 2011. After the commissioning phase [18][19][20], in December 2016, patient treatment sessions were monitored by the system.…”