Characterization of a microSilicon diode detector for small-field photon beam dosimetry

Akino, Yuichi; Fujiwara, Mika; Okamura, Keita; Shiomi, Hiroya; Mizuno, Hirokazu; Isohashi, Fumiaki; Сузукі, Осаму; Seo, Yuji; Tamari, Keisuke; Ogawa, Kazuhiko

doi:10.1093/jrr/rraa010

Cited by 26 publications

(30 citation statements)

References 29 publications

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“…Another Semiflex ionization chamber (model 31010) was used as a reference detector; however, this detector was not used for measurements of the TrueBeam photon beams with field sizes of ≤30 × 30 mm 2 . Note that OF , the beam profiles, and the PDD data of the CyberKnife beams measured by MD have been reported elsewhere 15 . IC was used as the reference detector for middle‐to‐large‐field sizes, whereas MD was used as the small‐field reference because of its previously reported suitable characteristics for small‐field dosimetry 3,16,17 …”

Section: Methodsmentioning

confidence: 99%

“…Note that OF, the beam profiles, and the PDD data of the CyberKnife beams measured by MD have been reported elsewhere. 15 IC was used as the reference detector for middle-to-large-field sizes, whereas MD was used as the small-field reference because of its previously reported suitable characteristics for small-field dosimetry. 3,16,17 In 2008, the IAEA/American Association of Physicists in Medicine (AAPM) proposed a formalism for the correction of OF values, 18 and IAEA TRS-483 provides correction factors (k f clin ,f msr Q clin ,Q msr ) that correct the detector output factor (OF det ) to obtain the field output factor (Ω f clin ,f msr Q clin ,Q msr ), for various detectors.…”

Section: C Scanning Data and Detector Output Factorsmentioning

confidence: 99%

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Technical Note: Characteristics of a microSilicon X shielded diode detector for photon beam dosimetry

et al. 2021

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This study investigated the characteristics of a new shielded diode detector, microSilicon X (model 60022: MSX), for small-field and large-field dosimetry. Methods: The percent depth dose (PDD), beam profiles, detector output factor (OF det ), temperature dependence, dose rate dependence, dose-per-pulse (DPP) dependence, and dose-response linearity of MSX were evaluated in Cyberknife and TrueBeam photon beams and compared with various detectors including microDiamond (PTW model 60019: MD), Sun Nuclear EDGE detector, Photon diode (PTW model 60016: PD), and semiflex ionization chamber (PTW model 31010: IC). Results: For field sizes ranging from 50 × 50 mm 2 to 400 × 400 mm 2 , MSX-measured OF det values were within 1% of the IC-measured values. For the CyberKnife small fields, the maximum difference between the MSX-measured OF det and the MD-measured field output factor (Ω) was 4.0%, while the maximum differences were 8.8% and 10.9% for PD and EDGE, respectively. MSX showed a stable response within 0.7% for water temperatures of 5°C to 34°C, while PD and EDGE showed a linear correlation between the water temperature and the response. MSX showed small variations within 0.2% for the dose rate, and PD and EDGE showed logarithmic increases in the response with the dose rate. MSX and MD had smaller DPP dependences than PD and EDGE. Conclusions: The characteristics of MSX for measurements of small-and large-field photon beams are favorable. Compared to PD, MSX exhibited significant improvement in the over-response for small fields. The OF det values measured by MSX were approximately in-between those measured by MD and PD. MSX showed stable responses against water temperature, dose rate, and DPP variations and provided suitable data for a wide range of field sizes. However, careful attention is required for measurements of OF det for field sizes of <10 × 10 mm 2 and PDD for field sizes of ≥200 × 200 mm 2 .

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Section: Methodsmentioning

confidence: 99%

Section: C Scanning Data and Detector Output Factorsmentioning

confidence: 99%

Technical Note: Characteristics of a microSilicon X shielded diode detector for photon beam dosimetry

et al. 2021

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“…126,231,232 However, the parallel irradiation of the Gafchromic™ EBT films is discouraged by Fontanarosa et al 233 who observed unacceptable under dosage in PDD at depths greater than 15 cm (about 5% at 20 cm). In general, the detectors that have smallest k f clin, f msr Q clin, Q msr factor (microdiamond, microslicon, plastic scintillator, EBT film) 78,85,97,123,156,158,[186][187][188]192,[234][235][236] are preferred to avoid the need to correct the PDD. If the institution is unable to justify acquisition of at least one of these systems, the method described by Francescon et al 237 and as described in Figure 5 could be adopted.…”

Section: Percentage Depth Dose (Pdd)mentioning

confidence: 99%

“…Recently, a new unshielded silicon diode detector (PTW-60023) known as a microSilicon detector with very small dimension (0.032 mm 3 with 1.5 mm diameter) with an epoxy density of 1.15 g/cm 3 was introduced and was found to have very suitable characteristics for small-field dosimetry for both linear accelerators and CyberKnife. [156][157][158][159] Even the new shielded diode (PTW-60022) showed a very good characteristics and superior results in very small photon fields. 160…”

Section: Diode Typesmentioning

confidence: 99%

Report of AAPM Task Group 155: Megavoltage photon beam dosimetry in small fields and non‐equilibrium conditions

et al. 2021

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Abbreviations: %dd(10) x , The photon component of the percent depth dose at 10 cm depth in water for a 10 cm 2 × 10 cm 2 field; L∕ w air , Restricted mass collision stopping power ratio of water to air; en ∕ , Spectrum-averaged mass energy-absorption coefficient; AAPM, American Association of Physicists in Medicine; CPE, Charged Particle Equilibrium; DLG, Dosimetric leaf gap; D f msr w,Q msr , Absorbed dose to water at the reference depth z ref in water in the absence of the detector in a field specified by f msr and beam quality Q msr .; f clin , Clinical (clin) non-reference radiation field; f msr , Machine-specific reference (msr) field; f ref , Reference field (ref) specified in dosimetry protocols for which the calibration coefficient of an ionization chamber in terms of absorbed dose to water is provided by a standards laboratory; FWHM, Full-width at half-maximum; GUM, Guide to the expression of Uncertainty in Measurements.; IAEA, International Atomic Energy Agency; ICRU, International Commission on Radiation Units and Measurements; IMRT, Intensity-modulated radiation therapy; k Q,Q 0 , The beam-quality correction factor, which corrects for the differences between the response of an ionization chamber in the reference beam of quality Q o used for calibrating the chamber and the beam of quality Q (defined as k Q . in TG-51 4 ); k f ref Q,Q 0 , Correction factor that accounts for the differences between the response of a detector in field f ref in a beam of quality Q and reference beam quality Q 0 as defined in TRS-483. 1 and Palmans et al 2 ; k fclin,fmsr Qclin,Q msr , The detector-specific correction factor that accounts for the difference between the responses of the detector in fields f clin in a beam of quality Q clin and in fields f msr in beam of quality Q msr as defined by Alfonso et al. 3 ; LCPE, Lateral charged particle equilibrium; M fmsr Qmsr , Detector reading in field f msr and beam quality Q msr corrected for influence of changes in pressure and temperature, incomplete charge collection, polarity effect and electrometer correction factor (TRS-483 1 ); MU, Monitor unit; N D,w,Q 0 , This is N D,w in TG-51, 4 and defined as the calibration coefficient in terms of absorbed dose to water for an ionization chamber at a reference beam of quality,Q 0 and field size f ref ; N f ref D,w,Q 0

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“…The novel PTW microSilicon detector may be an appropriate detector for measurements in high-energy small-field electron beams. The suitability of this small-volume detector for dosimetry in small photon beams was already investigated, showing very good dosimetric properties [8][9][10]. In addition, three-dimensional characterization of the active volumes of the PTW microSilicon has been performed for accurate Monte Carlo simulations of the detector [11].…”

Section: Introductionmentioning

confidence: 99%

Dosimetric Characterization of Small Radiation Therapy Electron Beams Collimated by Tubular Applicators With the New Micro-Silicon Detector

Russo¹,

Bettarini²,

Leonulli³

et al. 2021

Preprint

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High-energy small electron beams generated by linear accelerators are used for radiotherapy of localized superficial tumors. The aim of the present study is to assess the dosimetric performance under small radiation therapy electron beams of the novel PTW microSilicon detector by comparison with commercially available dosimeters. Relative dose measurements of circular fields with 20, 30, 40 and 50 mm aperture diameters were performed for 4 to 12 MeV energy range of electron beams generated by an Elekta Synergy linac. Percentage depth dose, transverse profiles and output factors normalized to the 10 × 10 cm2 reference field were measured. All dosimetric data were collected in a PTW MP3 motorized water phantom at SSD of 100cm by using the novel PTW microSilicon detector. The PTW diode E and the PTW microDiamond were also used in all beam aperture for benchmarking. Data for the biggest field size were also measured by the PTW Advanced Markus ionization chamber.Measurements performed by the microSilicon are in good agreement with the reference values for all the tubular applicators and beam energies, within the stated uncertainties. This confirms the reliability of the microSilicon detector for relative dosimetry of small radiation therapy electron beams collimated by tubular applicators.

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Characterization of a microSilicon diode detector for small-field photon beam dosimetry

Cited by 26 publications

References 29 publications

Technical Note: Characteristics of a microSilicon X shielded diode detector for photon beam dosimetry

Technical Note: Characteristics of a microSilicon X shielded diode detector for photon beam dosimetry

Report of AAPM Task Group 155: Megavoltage photon beam dosimetry in small fields and non‐equilibrium conditions

Dosimetric Characterization of Small Radiation Therapy Electron Beams Collimated by Tubular Applicators With the New Micro-Silicon Detector

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