Characterisation of Silicon Diode Arrays for Dosimetry in External Beam Radiation Therapy

Porumb, C.; Aldosari, A. H.; Fuduli, Iolanda; Cutajar, Dean L; Newall, Matthew; Metcalfe, Peter E; Carolan, Martin G; Lerch, Michael L. F; Perevertaylo, Vladimir; Rosenfeld, Anatoly B.; Petasecca, Marco

doi:10.1109/tns.2016.2567446

Cited by 7 publications

(5 citation statements)

References 40 publications

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“…In terms of response linearity with delivered dose, the bulk Octa results are, as expected, consistent with those of similar bulk devices previously characterized, such as the MP512 [34] and the Duo [33]. Figure 6 shows that the epitaxial Octa demonstrated an equally good linear response.…”

Section: B Linearitysupporting

confidence: 87%

“…The variation of I as a function of accumulated dose, which would reflect the increasing concentration of radiationinduced defects in the silicon and Si-SiO interfaces, has previously been characterized for similar bulk and epitaxial substrates elsewhere [18], [33].…”

Section: Uniformitymentioning

confidence: 99%

“…Based on previous radiation damage studies [33], it is estimated that the sensitivity of the bulk Octa has been reduced by approximately 55% as a consequence of its preirradiation. Conversely, the sensitivity of the epitaxial Octa, which was not pre-irradiated, could be expected to increase, albeit slightly, with future exposure to irradiation as a consequence of continuous clinical testing [18].…”

Section: Uniformitymentioning

confidence: 99%

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On Monolithic Silicon Array Detectors for Small-Field Photon Beam Dosimetry

Biasi

Davis

Petasecca

et al. 2018

IEEE Trans. Nucl. Sci.

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Contemporary x-ray radiotherapy employs small radiation fields to deliver highly conformal dose distributions. Submillimeter accuracy in the measurement of the delivered dose map is a crucial requirement of detectors proposed for quality assurance applications. 2D monolithic silicon array detectors can provide high spatial-resolution by optimizing small sensitive volumes (SVs) in a large active area. They offer a stable and near energy-independent response in megavoltage photon beams, good dose linearity and real-time read-out. The SVs are ion-implanted on a silicon wafer whose geometry and physical characteristics, such as resistivity and defects concentration, dramatically affect the detector performance. The Octa is a novel 2D monolithic silicon array detector dedicated to small-field dosimetry. Its 512 diode-SVs are arranged with a sub-millimeter pitch along 4 intersecting orthogonal linear arrays. We report on the experimental and numerical characterization (performed with Sentaurus Workbench within the Synopsys framework) of two Octa detectors, manufactured respectively on a bulk and on an epitaxial silicon substrate. The effects of resistivity and defects concentration profiles across their largearea monolithic silicon wafers is compared and discussed in terms of the response linearity with dose, response uniformity, charge-collection efficiency and clinical performance in the case of a small radiation field delivered with a flattening filter free beam.Abstract-Contemporary x-ray radiotherapy employs small radiation fields to deliver highly conformal dose distributions. Sub-millimetre accuracy in the measurement of the delivered dose map is a crucial requirement of detectors proposed for quality assurance applications.2D monolithic silicon array detectors can provide high spatialresolution by optimizing small sensitive volumes (SVs) in a large active area. They offer a stable and near energy-independent response in megavoltage photon beams, good dose linearity and real-time read-out. The SVs are ion-implanted on a silicon wafer whose geometry and physical characteristics, such as resistivity and defects concentration, dramatically affect the detector performance. The Octa is a novel 2D monolithic silicon array detector dedicated to small-field dosimetry. Its 512 diode-SVs are arranged with a sub-millimeter pitch along 4 intersecting orthogonal linear arrays.We report on the experimental and numerical characterization (performed with Sentaurus™ Workbench within the Synopsys ® framework) of two Octa detectors, manufactured respectively on a bulk and on an epitaxial silicon substrate. The effects of resistivity and defects concentration profiles across their largearea monolithic silicon wafers is compared and discussed in terms of the response linearity with dose, response uniformity, charge-collection efficiency and clinical performance in the case of a small radiation field delivered with a flattening filter free beam.Index Terms-2D monolithic silicon array detector, small-field dosimetry, flattening filter...

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Section: B Linearitysupporting

confidence: 87%

Section: Uniformitymentioning

confidence: 99%

Section: Uniformitymentioning

confidence: 99%

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On Monolithic Silicon Array Detectors for Small-Field Photon Beam Dosimetry

Biasi

Davis

Petasecca

et al. 2018

IEEE Trans. Nucl. Sci.

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“…Ionization chambers are the most established detectors for absolute dosimetry, however, they have a limited spatial resolution for dose distribution assessments and the same occurs with diodes mainly due to inevitable gaps between the detectors (Stelljes et al 2015, Fuduli et al 2016.…”

Section: Introductionmentioning

confidence: 99%

Using the optically stimulated luminescence technique for one- and two-dimensional dose mapping: a brief review

Gasparian¹,

Malthez²,

Rodrigues³

2022

Phys. Med. Biol.

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In respect of radiation dosimetry, several applications require dose distribution verification rather than absolute dosimetry. Most protocols use radiological and radiochromic films and ionization chambers or diode arrays for dose mapping. The films are disposable which causes the precision of the results dependent on film production variability. The measurements with arrays of ionization chambers or diodes mainly lack spatial resolution. This review aims to provide an overview of the use of optically stimulated luminescence detectors (OSLDs) for one-dimensional (1D) and two-dimensional (2D) dose mapping in different applications. It reviews the ideas, OSL materials, and applications related to the assessment of dose distribution using OSLDs in the form of film or ceramic plate (BeO). Additionally, it reviews research published in the international scientific literature from 1998 to 2021. As an outcome, a table containing the main characteristics of each relevant paper is shown. The results section was divided by the type of OSL material, and we briefly described the principal findings and the significant developments of each mentioned study such as film production and OSL reader assembly. The purpose of this study was to present an overview of the main findings of several research groups on the use of OSLD in the form of film or plate for 1D and 2D dose mapping. Finally, the potential future development of dose mapping using OSLD films was outlined.

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“…However, the limits of single-point measuring devices are approached when it comes to scanning the complex dose gradients generated by IMRT. This has prompted the development of a variety of novel linear-array and planar-array designs [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

Hydrogels for Three-Dimensional Ionizing-Radiation Dosimetry

Marrale

D’Errico

2021

Gels

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Radiation-sensitive gels are among the most recent and promising developments for radiation therapy (RT) dosimetry. RT dosimetry has the twofold goal of ensuring the quality of the treatment and the radiation protection of the patient. Benchmark dosimetry for acceptance testing and commissioning of RT systems is still based on ionization chambers. However, even the smallest chambers cannot resolve the steep dose gradients of up to 30–50% per mm generated with the most advanced techniques. While a multitude of systems based, e.g., on luminescence, silicon diodes and radiochromic materials have been developed, they do not allow the truly continuous 3D dose measurements offered by radiation-sensitive gels. The gels are tissue equivalent, so they also serve as phantoms, and their response is largely independent of radiation quality and dose rate. Some of them are infused with ferrous sulfate and rely on the radiation-induced oxidation of ferrous ions to ferric ions (Fricke-gels). Other formulations consist of monomers dispersed in a gelatinous medium (Polyacrylamide gels) and rely on radiation-induced polymerization, which creates a stable polymer structure. In both gel types, irradiation causes changes in proton relaxation rates that are proportional to locally absorbed dose and can be imaged using magnetic resonance imaging (MRI). Changes in color and/or opacification of the gels also occur upon irradiation, allowing the use of optical tomography techniques. In this work, we review both Fricke and polyacrylamide gels with emphasis on their chemical and physical properties and on their applications for radiation dosimetry.

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Characterisation of Silicon Diode Arrays for Dosimetry in External Beam Radiation Therapy

Cited by 7 publications

References 40 publications

On Monolithic Silicon Array Detectors for Small-Field Photon Beam Dosimetry

On Monolithic Silicon Array Detectors for Small-Field Photon Beam Dosimetry

Using the optically stimulated luminescence technique for one- and two-dimensional dose mapping: a brief review

Hydrogels for Three-Dimensional Ionizing-Radiation Dosimetry

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