106 research outputs found
Therapeutic proton beams: LET, RBE and microdosimetric spectra with gas and silicon detectors
No full textA sealed mini-TEPC able to work in gas-steady modality, a monolithic silicon device composed by a matrix of micrometric cylindrical diodes and a residual energy measurement stage and the silicon MicroPlus Bridge detector were used to perform microdosimetric measurements at the 62 MeV proton clinical SOBP of CATANA at the Southern National Laboratories of INFN (LNS - INFN, Catania, Italy). Measurements were taken at the same different positions in a PMMA phantom, in order to analyse the detector response differences.Finally, a weighting function was applied to the spectra to see if the microdosimetric detectors are able to monitor RBE data for glioma cells (U87) irradiated at six positions along the same modulated 62-MeV proton beam. The results obtained with the three microdosimeters are compared and discussed.This work was supported by the 5th Scientific Commission of the Italian Institute for Nuclear Physics (INFN)
Spectrum data for calculation of biological effectiveness of proton beams
No full textDatasets used in Bellinzona, E.V.; Grzanka, L.; Attili, A.; Tommasino, F.; Friedrich, T.; Krämer, M.; Scholz, M.; Battistoni, G.; Embriaco, A.; Chiappara, D.; Cirrone, G.A.P.; Petringa, G.; Durante, M.; Scifoni, E. Biological Impact of Target Fragments on Proton Treatment Plans: An Analysis Based on the Current Cross-Section Data and a Full Mixed Field Approach. Cancers 2021, 13, 4768. https://doi.org/10.3390/cancers1319476
A New Approach for NaI(Tl) Detector Efficiency Calibration Using 41Ar Radionuclide for Air Exhaust Systems
No full textArgon-41 is an essential gaseous radionuclide that must be monitored in gaseous effluents from nuclear facilities. Therefore, a precise evaluation of Ar-41 activity is highly desired. Gamma spectroscopy with a NaI(Tl) scintillation detector coupled with a multichannel analyzer (MCA) is one of the widely used techniques for the identification and activity measurements of radioisotopes. However, the efficiency calibration of these kinds of monitoring systems highly depends on the source-detector geometry, and a large amount of uncertainty may complicate the calibration. This paper presents the evaluation of the full peak efficiency of a 2 x 2-in. NaI(Tl) scintillation detector coupled with a stable MCA for a Ar-41 source with 1293.5 keV energy in two different source-detector geometries, duct and Marinelli beaker, using the FLUKA code. A new experimental technique is considered to produce Ar-41 in a controlled geometry, like a Marinelli beaker, through neutron irradiation of natural argon inside a cyclotron bunker. The simulation data were compared with the experimental results for Marinelli beaker geometry, and the ratio was evaluated as 0.99 +/- 0.07. The ratio was considered a scaling factor for the final efficiency calibration of duct geometry
Microdosimetry with a sealed mini-TEPC and a silicon telescope at a clinical proton SOBP of CATANA
No full textA sealed miniaturized Tissue Equivalent Proportional Counter (mini-TEPC) able to work in gas-steady modality was developed at the Legnaro National Laboratories of the Italian National Institute of Nuclear Physics (LNL – INFN, Legnaro, Italy).
The aim of the present work is to compare the response of this mini-TEPC with that of a silicon microdosimeter based on a monolithic telescope.
Pairwise measurements were performed at the 62 MeV proton clinical Spread Out Bragg Peak (SOBP) of CATANA at the Southern National Laboratories of INFN (LNS – INFN, Catania, Italy). The dose mean lineal
energy values were derived from the spectra measured with the two detectors and compared with the total doseaveraged LET calculated by means of Geant4 Monte Carlo simulations. Finally, the possibility to apply the
Microdosimetric Kinetic Model (MKM) to reproduce RBE variations with depth along the Spread Out Bragg Peak was investigated.This work was supported by the 5th Scientific Commission of the Italian Institute for Nuclear Physics (INFN), the Belgian nuclear research Centre SCK•CEN and Hasselt University. This work has been partially supported by the ENEN+ project that has received funding from the EURATOM research and training Work Programme 2016 – 2017 – 1 #755576
Experimental validation of the filtering approach for dose monitoring in proton therapy at low energy
No full textThe higher physical selectivity of proton therapy demands higher accuracy in monitoring of the delivered dose, especially when the target volume is located next to critical organs and a fractionated therapy is applied. A method to verify a treatment plan and to ensure the high quality of the hadrontherapy is to use Positron Emission Tomography (PET), which takes advantage of the nuclear reactions between protons and nuclei in the tissue during irradiation producing β+-emitting isotopes. Unfortunately, the PET image is not directly proportional to the delivered radiation dose distribution; this is the reason why, at the present time, the verification of depth dose profiles with PET techniques is limited to a comparison between the measured activity and the one predicted for the planned treatment by a Monte Carlo model. In this paper we test the feasibility of a different scheme, which permits to reconstruct the expected PET signal from the planned radiation dose distribution along beam direction in a simpler and more direct way. The considered filter model, based on the description of the PET image as a convolution of the dose distribution with a filter function, has already demonstrated its potential applicability to beam energies above 70 MeV. Our experimental investigation provides support to the possibility of extending the same approach to the lower energy range ([40, 70] MeV), in the perspective of its clinical application in eye proton therapy
An "in-beam PET" prototype for proton therapy: preliminary results using targets of different composition
No full textPreliminary results of an in-beam PET prototype for proton therapy
No full textProton 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 directio
Heavy ions fragmentations measurements at intermediate energies in hadrontherapy and spatial vehicles shielding
No full textThe study of the nuclear fragmentation process involves many fields of interest, from the hadrontherapy, the new frontier for cancer therapy, to the spatial vehicles shielding design, to work safely in space with acceptable risks from galactic cosmic ray. Indeed, the measure of the fragmentation cross sections is an important information to estimate how this process modifies dose distributions and biological effectiveness. At present, simulations with analytical codes are used to deal with these problems. Such approach presents considerable uncertainty, especially because of a reduced number of experimental data, both on the fragmentation cross sections and on the different radiation biological effectiveness. All these reasons claimed more fragmentation cross section data, in a wide energy range and with different ions and materials
Reduction of the amount of yield data for KLM using set cover
No full textIn the Revenue Management department of KLM the prices for tickets are determined. The information of the prices are sent to a reservation system, in the form of yield data points. A reser- vation system is an external company that takes care of the selling of the tickets to the consumers for multiple airlines. The reservation system sets a restriction of 100 million yield data points. Because of the merger of KLM and Air France the Revenue Management systems are combined. Both companies generate about 70 million yield data points and therefore the restriction will be exceeded when the departments are combined. In my project I looked at the possibilities of reducing the amount of yield data in order to satisfy to the restrictions of the reservation system. This problem can be seen as the mathematical set cover problem, which is an NP-hard optimization problem. With the use of two solution methods, I found some surprising results to reduce the amount of yield data.Applied MathematicsElectrical Engineering, Mathematics and Computer Scienc
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