Online proton therapy monitoring: clinical test of a Silicon-photodetector-based in-beam PET (original) (raw)
Related papers
First tests for an online treatment monitoring system with in-beam PET for proton therapy
Journal of Instrumentation, 2015
PET imaging is a non-invasive technique for particle range verification in proton therapy. It is based on measuring the β + annihilations caused by nuclear interactions of the protons in the patient. In this work we present measurements for proton range verification in phantoms, performed at the CNAO particle therapy treatment center in Pavia, Italy, with our 10 x 10 cm 2 planar PET prototype DoPET. PMMA phantoms were irradiated with mono-energetic proton beams and clinical treatment plans, and PET data were acquired during and shortly after proton irradiation. We created 1-D profiles of the β + activity along the proton beam-axis, and evaluated the difference between the proximal rise and the distal fall-off position of the activity distribution. A good agreement with FLUKA Monte Carlo predictions was obtained. We also assessed the system response when the PMMA phantom contained an air cavity. The system was able to detect these cavities quickly after irradiation.
In-Beam Pet Monitoring Technique for Proton Therapy: Experimental Data and Monte Carlo Prediction
RAD Conference Proceedings, 2019
Charged particle therapy is a precise radiotherapy method for the treatment of solid tumors. This method can deliver conformal dose distributions minimizing damage to healthy tissues thanks to its characteristic dose profile. However, the steep dose profile of charged particle beams (due to the Bragg peak) can result in over-or under-dosage in critical regions. Monitoring the range of the charged particles is therefore highly desirable. In this study, we use a planar in-beam PET system for the range verification of pencil beams in proton therapy. The planar geometry of the DoPET system is advantageous because it can be used online, i.e., during treatment. In the particle therapy community, the Monte Carlo (MC) codes are widely used to evaluate the radiation transport and interaction with matter. For this reason, the FLUKA MC code was used to simulate the experimental conditions of irradiations performed at the Cyclotron Centre Bronowice (CCB) proton therapy center in Krakow (PL). 130MeV pencil beams were delivered on phantoms mimicking human tissues. Different acquisitions are analyzed and compared with the MC predictions. The image reconstruction for experimental data and simulation is based on the Maximum Likelihood Estimation Method (MLEM) algorithm. A special focus in the paper will be on the validation of the PET detector response for activity range verification.
Monitoring Proton Therapy Through In-Beam PET: An Experimental Phantom Study
IEEE Transactions on Radiation and Plasma Medical Sciences, 2019
In this work, we investigate the use of a PET system to monitor the proton therapy. The monitoring procedure is based on the comparison between the β+activity generated in the irradiated volume during the treatment, with the β+activity distribution obtained with Monte Carlo simulation. The dedicated PET system is a dual head detection system; each head is composed of nine scintillating LYSO crystal matrices read out independently with a custom modularized acquisition system. Our experimental data were acquired at the Cyclotron Centre Bronowice, Institute Nuclear Physics in Krakow, Poland and were simulated with the FLUKA Monte Carlo code. Homogeneous and heterogeneous plastic phantoms were irradiated with monoenergetic 130-MeV protons. The capabilities of our PET system to distinguish different irradiated materials were investigated, and the proton pencil beams were used as probes. Our focus was to analyze the activity width and the total activity event number in several cases. Irradiations were performed using either single pencil beams one at a time, or two pencil beams during the same data taking. The comparison of 1D activity profile for experimental data and MC simulation were always in good agreement showing that, the treatment quality assessment in proton therapy can be based on β+ activity measurements.
A PET Prototype for “In-Beam” Monitoring of Proton Therapy
IEEE Transactions on Nuclear Science, 2009
The in-beam PET is a novel PET application to image the β β β β + activity induced in biological tissues by hadronic therapeutic beams. Thanks to the correlation existing between beam-delivered dose profiles and beam-induced activity profiles, in vivo information about the effective ion paths can be extracted from the in-beam PET image. In-situ measurements, immediately after patient irradiation, are recommended in order to exploit the maximum statistics, by detecting the contribution provided by short lived isotopes. A compact, dedicated tomograph should then be developed for such an application, so as to be used in the treatment room.
Preliminary results of an in-beam PET prototype for proton therapy
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2008
Proton therapy can overcome the limitations of conventional radiotherapy due to the more selective energy deposition in depth and to the increased biological effectiveness. Verification of the delivered dose is desirable, but the complete stopping of the protons in patient prevents the application of electronic portal imaging methods that are used in conventional radiotherapy During proton therapy β+ emitters like 11C, 15O, 10C are generated in irradiated tissues by nuclear reactions. The measurement of the spatial distribution of this activity, immediately after patient irradiation, can lead to information on the effective delivered dose. First, results of a feasibility study of an in-beam PET for proton therapy are reported. The prototype is based on two planar heads with an active area of about 5×5 cm2. Each head is made up of a position sensitive photomultiplier coupled to a square matrix of same size of LYSO scintillating crystals (2×2×18 mm3 pixel dimensions). Four signals from each head are acquired through a dedicated electronic board that performs signal amplification and digitization. A 3D reconstruction of the activity distribution is calculated using an expectation maximization algorithm. To characterize the PET prototype, the detection efficiency and the spatial resolution were measured using a point-like radioactive source. The validation of the prototype was performed using 62 MeV protons at the CATANA beam line of INFN LNS and PMMA phantoms. Using the full energy proton beam and various range shifters, a good correlation between the position of the activity distal edge and the thickness of the beam range shifter was found along the axial direction.
A PET Prototype for “In-Beam” Monitoring of Proton Therapy
IEEE Transactions on Nuclear Science, 2000
The in-beam PET is a novel PET application to image the + activity induced in biological tissues by hadronic therapeutic beams. Thanks to the correlation existing between beam-delivered dose profiles and beam-induced activity profiles, in vivo information about the effective ion paths can be extracted from the in-beam PET image. In-situ measurements, immediately after patient irradiation, are recommended in order to exploit the maximum statistics, by also detecting the contribution provided by the very short lived isotopes, e.g. 15 O. A compact, dedicated tomograph should then be developed for such an application, so as to be used in the treatment room.
Pet imaging of dose distribution in proton-beam cancer therapy
Nuclear Technology and Radiation Protection, 2005
Proton therapy is a treatment modality of increasing utility in clinical radiation oncology mostly because its dose distribution conforms more tightly to the target volume than X-ray radiation therapy. One important feature of proton therapy is that it produces a small amount of positron-emitting isotopes along the beam-path through the non-elastic nuclear interaction of protons with target nuclei such as 12C, 14N, and 16O. These radio isotopes, mainly 11C, 13N, and 15O, al low imaging the therapy dose distribution using positron emission tomography. The resulting positron emission tomography images provide a powerful tool for quality assurance of the treatment, especially when treating inhomogeneous organs such as the lungs or the head-and-neck, where the calculation of the dose distribution for treatment planning is more difficult. This pa per uses Monte Carlo simulations to predict the yield of positron emitters produced by a 250 MeV proton beam, and to simulate the productions o...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
In this study the possibility of retrieving composition information in proton therapy with a planar in-beam PET scanner is investigated. The analysis focuses both on spatial activity distributions and time dependence of the recorded signal. The experimental data taking was performed at the Trento Proton Therapy Center (IT) by irradiating three different phantoms. We show that different phantom compositions reflect into different activity profile shapes. We demonstrate that the analysis of the event rate can provide significant information on the phantom elemental composition, suggesting that elemental analysis could be used along with activity profile analysis to achieve a more accurate treatment monitoring.
Analysis of time-profiles with in-beam PET monitoring in charged particle therapy
CINECA IRIS Institutial research information system (University of Pisa), 2018
Background: Treatment verification with PET imaging in charged particle therapy is conventionally done by comparing measurements of spatial distributions with Monte Carlo (MC) predictions. However, decay curves can provide additional independent information about the treatment and the irradiated tissue. Most studies performed so far focus on long time intervals. Here we investigate the reliability of MC predictions of space and time (decay rate) profiles shortly after irradiation, and we show how the decay rates can give an indication about the elements of which the phantom is made up. Methods and Materials: Various phantoms were irradiated in clinical and nearclinical conditions at the Cyclotron Centre of the Bronowice proton therapy centre. PET data were acquired with a planar 16x16 cm 2 PET system. MC simulations of particle interactions and photon propagation in the phantoms were performed using the FLUKA code. The analysis included a comparison between experimental data and MC simulations of space and time profiles, as well as a fitting procedure to obtain the various isotope contributions in the phantoms. Results and conclusions: There was a good agreement between data and MC predictions in 1-dimensional space and decay rate distributions. The fractions of 11 C, 15 O and 10 C that were obtained by fitting the decay rates with multiple simple exponentials generally agreed well with the MC expectations. We found a small excess of 10 C in data compared to what was predicted in MC, which was clear especially in the PE phantom.
Characterization of an In-Beam PET Prototype for Proton Therapy With Different Target Compositions
IEEE Transactions on Nuclear Science, 2000
At the University of Pisa, the DoPET (Dosimetry with a Positron Emission Tomograph) project has focused on the development and characterization of an ad hoc, scalable, dual-head PET prototype for in-beam treatment planning verification of the proton therapy. In this paper we report the first results obtained with our current prototype, consisting of two opposing lutetium yttrium orthosilicate (LYSO) detectors, each one covering an area of 4.5 4.5 cm 2 . We measured the + -activation induced by 62 MeV proton beams at Catana facility (LNS, Catania, Italy) in several plastic phantoms. Experiments were performed to evaluate the possibility to extract accurate phantom geometrical information from the reconstructed PET images.