Development of an inorganic scintillating mixture for proton beam verification dosimetry

Safai, Sairos; Lin, Shixiong; Pedroni, E.

doi:10.1088/0031-9155/49/19/013

Cited by 50 publications

(39 citation statements)

References 22 publications

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“…An inorganic scintillating detector was also studied for proton beam dosimetry verification. 18 Small volume solid state detectors, such as silicon diodes and diamond detectors, seem to be the most promising instruments for relative dosimetric measurements of clinical proton beams. 6,12,19 Due to its outstanding properties, such as high radiation hardness, near tissue equivalence, small size, and low leakage current, diamond has long been considered an ideal material for the construction of small volume high-resolution radiation detectors.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the dosimetric properties of a synthetic single crystal diamond detector in high energy clinical proton beams

Mandapaka¹,

Ghebremedhin²,

Patyal³

et al. 2013

Medical Physics

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Purpose: To investigate the dosimetric properties of a synthetic single crystal diamond Schottky diode for accurate relative dose measurements in large and small field high-energy clinical proton beams. Methods:The dosimetric properties of a synthetic single crystal diamond detector were assessed by comparison with a reference Markus parallel plate ionization chamber, an Exradin A16 microionization chamber, and Exradin T1a ion chamber. The diamond detector was operated at zero bias voltage at all times. Comparative dose distribution measurements were performed by means of Fractional depth dose curves and lateral beam profiles in clinical proton beams of energies 155 and 250 MeV for a 14 cm square cerrobend aperture and 126 MeV for 3, 2, and 1 cm diameter circular brass collimators. ICRU Report No. 78 recommended beam parameters were used to compare fractional depth dose curves and beam profiles obtained using the diamond detector and the reference ionization chamber. Warm-up/stability of the detector response and linearity with dose were evaluated in a 250 MeV proton beam and dose rate dependence was evaluated in a 126 MeV proton beam. Stem effect and the azimuthal angle dependence of the diode response were also evaluated. Results: A maximum deviation in diamond detector signal from the average reading of less than 0.5% was found during the warm-up irradiation procedure. The detector response showed a good linear behavior as a function of dose with observed deviations below 0.5% over a dose range from 50 to 500 cGy. The detector response was dose rate independent, with deviations below 0.5% in the investigated dose rates ranging from 85 to 300 cGy/min. Stem effect and azimuthal angle dependence of the diode signal were within 0.5%. Fractional depth dose curves and lateral beam profiles obtained with the diamond detector were in good agreement with those measured using reference dosimeters. Conclusions:The observed dosimetric properties of the synthetic single crystal diamond detector indicate that its behavior is proton energy independent and dose rate independent in the investigated energy and dose rate range and it is suitable for accurate relative dosimetric measurements in large as well as in small field high energy clinical proton beams.

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Section: Introductionmentioning

confidence: 99%

Evaluation of the dosimetric properties of a synthetic single crystal diamond detector in high energy clinical proton beams

Mandapaka¹,

Ghebremedhin²,

Patyal³

et al. 2013

Medical Physics

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“…The use of stacks of films (Lomax et al 2001) gives dose information with very high spatial resolution, but the film measurement evaluation is time consuming. Scintillating screens (Boon et al 1998, Safai et al 2004 coupled to a CCD camera allow online measurements of dose distributions with a 2D spatial resolution nearly as good as the film in a plane perpendicular to the beam. However, their response suffers from saturation.…”

Section: Introductionmentioning

confidence: 99%

A scintillating gas detector for 2D dose measurements in clinical carbon beams

Seravalli¹,

Boer²,

Geurink

et al. 2008

Phys. Med. Biol.

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A two-dimensional position sensitive dosimetry system based on a scintillating gas detector has been developed for pre-treatment verification of dose distributions in hadron therapy. The dosimetry system consists of a chamber filled with an Ar/CF 4 scintillating gas mixture, inside which two cascaded gas electron multipliers (GEMs) are mounted. A GEM is a thin kapton foil with copper cladding structured with a regular pattern of sub-mm holes. The primary electrons, created in the detector's sensitive volume by the incoming beam, drift in an electric field towards the GEMs and undergo gas multiplication in the GEM holes. During this process, photons are emitted by the excited Ar/CF 4 gas molecules and detected by a mirror-lens-CCD camera system. Since the amount of emitted light is proportional to the dose deposited in the sensitive volume of the detector by the incoming beam, the intensity distribution of the measured light spot is proportional to the 2D hadron dose distribution. For a measurement of a 3D dose distribution, the scintillating gas detector is mounted at the beam exit side of a water-bellows phantom, whose thickness can be varied in steps. In this work, the energy dependence of the output signal of the scintillating gas detector has been verified in a 250 MeV/u clinical 12 C ion beam by means of a depth-dose curve measurement. The underestimation of the measured signal at the Bragg peak depth is only 9% with respect to an airfilled ionization chamber. This is much smaller than the underestimation found for a scintillating Gd 2 O 2 S:Tb ('Lanex') screen under the same measurement conditions (43%). Consequently, the scintillating gas detector is a promising device for verifying dose distributions in high LET beams, for example to check hadron therapy treatment plans which comprise beams with different energies.

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“…3.9 is the emission spectrum from Gadox and other compounds from Ref. [168]. One can see that there are multiple emission bands in Gadox, and that the main emission is at 545 nm.…”

Section: : Radiative Relaxationmentioning

confidence: 94%

Control of Laser Plasma Based Accelerators up to 1 GeV

Nakamura

2007

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This dissertation documents the development of a broadband electron spectrometer (ESM) for GeV class Laser Wakefield Accelerators (LWFA), the production of high quality GeV electron beams (e-beams) for the first time in a LWFA by using a capillary discharge guide (CDG), and a statistical analysis of CDG-LWFAs.An ESM specialized for CDG-LWFAs with an unprecedentedly wide momentum acceptance, from 0.01 to 1.1 GeV in a single shot, has been developed. Simultaneous measurement of e-beam spectra and output laser properties as well as a large angular acceptance (> ±10 mrad) were realized by employing a slitless scheme. A scintillating screen (LANEX Fast back ,LANEX-FB) -camera system allowed faster than 1 Hz operation and evaluation of the spatial properties of e-beams. The design provided sufficient resolution for the whole range of the ESM (below 5% for beams with 2 mrad divergence).The calibration between light yield from LANEX-FB and total charge, and a study on the electron energy dependence (0.071 to 1.23 GeV) of LANEX-FB were performed at the Advanced light source (ALS), Lawrence Berkeley National Laboratory (LBNL). Using this calibration data, the developed ESM provided a charge measurement as well.The production of high quality electron beams up to 1 GeV from a centimeter-scale ii accelerator was demonstrated. The experiment used a 310 µm diameter gas-filled capillary discharge waveguide that channeled relativistically-intense laser pulses (42 TW, A statistical analysis of the CDG-LWFAs' performance was carried out. By taking advantage of the high repetition rate experimental system, several thousands of shots were taken in a broad range of the laser and plasma parameters. An analysis program was developed to sort and select the data by specified parameters, and then to evaluate performance statistically.The analysis suggested that the generation of GeV-level beams comes from a highly unstable and regime. By having the plasma density slightly above the threshold density for self injection, 1) the longest dephasing length possible was provided, which led to the generation of high energy e-beams, and 2) the number of electrons injected into the wakefield was kept small, which led to the generation of high quality (low energy spread) e-beams by minimizing the beam loading effect on the wake. The analysis of the stable half-GeV beam regime showed the requirements for stable self injection and acceleration. A small change of discharge delay t dsc , and input energy E in , significantly affected performance.The statistical analysis provided information for future optimization, and suggested possible schemes for improvment of the stability and higher quality beam generation. A CDG-LWFA is envisioned as a construction block for the next generation accelerator, enabling significant cost and size reductions.

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Development of an inorganic scintillating mixture for proton beam verification dosimetry

Cited by 50 publications

References 22 publications

Evaluation of the dosimetric properties of a synthetic single crystal diamond detector in high energy clinical proton beams

Evaluation of the dosimetric properties of a synthetic single crystal diamond detector in high energy clinical proton beams

A scintillating gas detector for 2D dose measurements in clinical carbon beams

Control of Laser Plasma Based Accelerators up to 1 GeV

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