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1.
Appl Radiat Isot ; 166: 109363, 2020 Dec.
Article in English | MEDLINE | ID: mdl-32877863

ABSTRACT

The E_LIBANS project (INFN) aims at producing neutron facilities for interdisciplinary irradiation purposes among which pre-clinical research for BNCT. After the successful setting-up of the thermal neutron source based on a medical LINAC, a similar apparatus for epithermal neutrons has been developed. Both structures are based on an Elekta 18 MV coupled with a photoconverter-moderator system which deploys the (γ,n) reaction to convert the X-rays into neutrons. This communication describes the two neutron sources and the results obtained in their characterization.


Subject(s)
Boron Neutron Capture Therapy/instrumentation , Neutrons , Particle Accelerators/instrumentation , Animals , Boron Neutron Capture Therapy/statistics & numerical data , Computer Simulation , Equipment Design , Humans , Italy
2.
Appl Radiat Isot ; 142: 38-41, 2018 Dec.
Article in English | MEDLINE | ID: mdl-30248587

ABSTRACT

CSYP (CYlindrical SPectrometer) is a directional neutron spectrometer based on a single moderator embedding multiple thermal neutron detectors. Similarly to Bonner Spheres, CYSP responds from thermal up to GeV neutrons and the spectrum is obtained via few-channel unfolding methods. CYSP has the shape of a polyethylene cylinder with diameter 50 cm and height 65 cm. Owing on a thick collimator and on a specifically designed shielding structure, the internal detectors only respond to neutrons coming from a known direction. Internal thermal neutron detectors are one-cm2 6LiF-covered silicon diodes. Un upgraded version of CYPS was developed to work in low intensity applications, such as cosmic field measurements. It is called CYSP-HS (High-Sensitivity) and is equipped with large area 6LiF-covered silicon diodes (LATND, Large Area Thermal Neutron Detectors). Compared with the former CYSP, the sensitivity increased approximately by an order of magnitude. This paper presents CYSP-HS focusing on the new internal detectors, the response matrix and its verification in a reference field of Am-Be available at the Politecnico di Milano.

3.
Phys Med ; 52: 113-121, 2018 Aug.
Article in English | MEDLINE | ID: mdl-30139599

ABSTRACT

PURPOSE: The aim of this paper is to investigate the limits of LET monitoring of therapeutic carbon ion beams with miniaturized microdosimetric detectors. METHODS: Four different miniaturized microdosimeters have been used at the 62 MeV/u 12C beam of INFN Southern National Laboratory (LNS) of Catania for this purpose, i.e. a mini-TEPC and a GEM-microdosimeter, both filled with propane gas, and a silicon and a diamond microdosimeter. The y-D (dose-mean lineal energy) values, measured at different depths in a PMMA phantom, have been compared withLET¯D (dose-mean LET) values in water, calculated at the same water-equivalent depth with a Monte Carlo simulation setup based on the GEANT4 toolkit. RESULTS: In these first measurements, no detector was found to be significantly better than the others as a LET monitor. The y-D relative standard deviation has been assessed to be 13% for all the detectors. On average, the ratio between y-D and LET¯D values is 0.9 ±â€¯0.3, spanning from 0.73 ±â€¯0.08 (in the proximal edge and Bragg peak region) to 1.1 ±â€¯0.3 at the distal edge. CONCLUSIONS: All the four microdosimeters are able to monitor the dose-mean LET with the 11% precision up to the distal edge. In the distal edge region, the ratio of y-D to LET¯D changes. Such variability is possibly due to a dependence of the detector response on depth, since the particle mean-path length inside the detectors can vary, especially in the distal edge region.


Subject(s)
Radiometry/instrumentation , Calibration , Carbon Isotopes/therapeutic use , Computer Simulation , Equipment Design , Heavy Ion Radiotherapy/instrumentation , Miniaturization , Monte Carlo Method , Phantoms, Imaging , Polymethyl Methacrylate , Radiotherapy Dosage , Water
4.
Radiat Prot Dosimetry ; 180(1-4): 304-308, 2018 Aug 01.
Article in English | MEDLINE | ID: mdl-29361156

ABSTRACT

Radiation-resistant, gamma-insensitive, active thermal neutron detectors were developed to monitor the thermal neutron cavity of the E_LIBANS project. Silicon and silicon carbide semiconductors, plus vented air ion chambers, were chosen for this purpose. This communication describes the performance of these detectors, owing on the results of dedicated measurement campaigns.


Subject(s)
Carbon Compounds, Inorganic/chemistry , Neutrons , Radiation Monitoring/instrumentation , Radiation Monitoring/methods , Radiation Protection/instrumentation , Semiconductors/standards , Silicon Compounds/chemistry , Silicon/chemistry , Computer Simulation , Equipment Design , Radiation Dosage , Temperature
5.
Radiat Prot Dosimetry ; 180(1-4): 273-277, 2018 Aug 01.
Article in English | MEDLINE | ID: mdl-29309701

ABSTRACT

The e_LiBANS project aims at producing intense thermal neutron fields for diverse interdisciplinary irradiation purposes. It makes use of a reconditioned medical electron LINAC, recently installed at the Physics Department and INFN in Torino, coupled to a dedicated photo-converter, developed within this collaboration, that uses (γ,n) reaction within high Z targets. Produced neutrons are then moderated to thermal energies and concentrated in an irradiation volume. To measure and to characterize in real time the intense field inside the cavity new thermal neutron detectors were designed with high radiation resistance, low noise and very high neutron-to-photon discrimination capability. This article offers an overview of the e_LiBANS project and describes the results of the benchmark experiment.


Subject(s)
Neutrons , Particle Accelerators , Photons , Radiation Dosage , Radiometry/instrumentation , Electrons , Equipment Design , Gamma Rays , Interdisciplinary Research , Linear Models
6.
Orthod Craniofac Res ; 14(4): 222-33, 2011 Nov.
Article in English | MEDLINE | ID: mdl-22008302

ABSTRACT

OBJECTIVE: To assess transversal tooth movements and buccal bone modeling of maxillary lateral segments achieved with active or passive self-ligating bracket systems in a randomized clinical trial. MATERIALS AND METHODS: Sixty-four patients, with Class I, II, and mild Class III malocclusions, were randomly assigned to treatment with passive (Damon 3 MX) or active (In-Ovation R) SLBs. Impressions and cone-beam CT-scans were taken before (T0) and after treatment (T1). Displacement of maxillary canines, premolars and molars, and buccal alveolar bone modeling were blindly assessed. RESULTS: Twenty-one patients in the Damon and 20 in the In-Ovation group completed treatment according to the prescribed protocol. Eight Damon and 10 In-Ovation patients were excluded as the treatment approach had to be changed because of deviation from the recommended initial plan, while three Damon and two In-Ovation patients did not complete the treatment. Transversal expansion of the upper arch was achieved by buccal tipping in all but one patient in each group. No statistical significant difference in inter-premolar bucco-lingual inclination was found between the two groups from T0 to T1. The bone area buccal to the 2nd premolar decreased on average of 20% in the Damon and 14% in the In-Ovation group. Only few patients exhibited widening of the alveolar process. CONCLUSION: The anticipated translation and buccal bone modeling using active or passive SLBs could not be confirmed. Because of the large interindividual variation, a patient-specific analysis seems to be mandatory as individual factors like pre-treatment teeth inclination and occlusion influenced the treatment outcome of the individual patients.


Subject(s)
Alveolar Process/pathology , Malocclusion/therapy , Maxilla/pathology , Orthodontic Appliance Design , Orthodontic Brackets , Tooth Movement Techniques/instrumentation , Tooth/pathology , Adolescent , Adult , Bicuspid/pathology , Bone Remodeling/physiology , Cephalometry/methods , Child , Cone-Beam Computed Tomography/methods , Cuspid/pathology , Follow-Up Studies , Humans , Imaging, Three-Dimensional/methods , Malocclusion, Angle Class I/therapy , Malocclusion, Angle Class II/therapy , Malocclusion, Angle Class III/therapy , Models, Dental , Molar/pathology , Treatment Outcome
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