Methods and advanced Equipment for Simulation and Treatment in Radiation Oncology: programa MAESTRO

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Dosimetric characterization with 62 MeV protons of a silicon-segmented detector for 2D dose verifications in radiotherapy

Abstract Due to the features of the modern radiotherapy techniques, namely intensity modulated radiation therapy and proton therapy, where high spatial dose gradients are often present, detectors to be employed for 2D dose verifications have to satisfy very narrow requirements. In particular they have to show high spatial resolution. In the framework of the European Integrated Project—Methods and Advanced Equipment for Simulation and Treatment in Radio-Oncology (MAESTRO, no. LSHC-CT-2004-503564), a dosimetric detector adequate for 2D pre-treatment dose verifications was developed. It is a modular detector, based on a monolithic silicon-segmented sensor, with an n-type implantation on an epitaxial p-type layer. Each pixel element is 2×2 mm 2 and the distance center-to-center is 3 mm. The sensor is composed of 21×21 pixels. In this paper, we report the dosimetric characterization of the system with a proton beam. The sensor was irradiated with 62 MeV protons for clinical treatments at INFN-Laboratori Nazionali del Sud (LNS) Catania. The studied parameters were repeatability of a same pixel, response linearity versus absorbed dose, and dose rate and dependence on field size. The obtained results are promising since the performances are within the project specifications

Natural and CVD type diamond detectors as dosimeters in hadrontherapy applications

Abstract Diamond is potentially a suitable material for use as radiation dosimeter; the wide band gap results in low dark currents and low sensitivity to visible light, the high carrier mobility can give rapid response, the very high density of strong bonds in the crystal structure make diamond very resistent to radiation damage; moreover it is tissue equivalent. The more recent advances in the synthesis of polycrystalline diamond by chemical vapour deposition (CVD) techniques have allowed the synthesis of material with electronic properties suitable for dosimetric application. In this paper we will report the results obtained in the study of the response of a natural diamond dosimeter and a CVD one irradiated with 62 AMeV proton beams to demonstrate their possible application in protontherapy

Dosimetric characterization of CVD diamonds irradiated with 62 MeV proton beams

Diamond is potentially a very suitable material for use as on-line radiation dosimeter. Recent advances in the synthesis of polycrystalline diamond by chemical vapor deposition (CVD) techniques have produced material with electronic properties suitable for dosimetry applications. In this work the possibility to use a segmented commercial CVD detector in the dosimetry of proton beams has been investigated. The response as function of dose, dose rate, the priming and the rise time have been investigated thoroughly. This study shows the suitability of CVD diamond for dosimetry of clinical 62 MeV proton beams. r 2005 Elsevier B.V. All rights reserved

2D dosimeter based on monolithic silicon sensors for beam verification in conformal radiotherapy

Due to the features of modern radiotherapy techniques, such as Intensity Modulated Radiation Therapy (IMRT), Stereotactic Treatments with photons and proton therapy, where high spatial dose gradient are often present, detectors to be employed for two-dimensional dose verifications must satisfy narrow requirements. In particular, they have to exhibit high spatial resolution. For these applications, in the framework of the European Integrated project MAESTRO (LSHC-CT-2004-503564) and of the INFN experiment PRIMA, we designed a modular system based on a monolithic silicon segmented sensor. A single sensor has been coupled with readout electronics and tested with satisfactory results by using 6, 10 and 25MV X-rays from a LINAC at the University Hospital of Florence and 62MeV protons at INFN LNS Catania, following MAESTRO procedures. For photons, almost all the channels exhibit performances within project specifications (repeatability ≪0.5%, reproducibility ≪1%, deviation from linearity ≪1%, dose rate dependence ≪1%). For protons, the measured Spread Out Bragg Peak is in good agreement with the one measured with a single diode and the detector shows also a good linearity in the range 20–5000 cGy. The output factors are in agreement with those measured with ionization chamber, single diode or film, within experimental errors