Spectroscopic characterization of a novel electronic brachytherapy system

Liu, Derek; Poon, Emily; Bazalova, M.; Reniers, Brigitte; Evans, Michael D.; Rusch, Thomas W.; Verhaegen, Frank

doi:10.1088/0031-9155/53/1/004

Cited by 44 publications

(40 citation statements)

References 24 publications

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“…This source exhibited depth dose behavior similar to low-energy photon-emitting low dose rate sources 125 I and 103 Pd, yet with capability for variable and much higher dose rates, and subsequently adjustable pe netration possibilities. Liu et al [14] performed the spectral and attenuation curve measurements to characterize it in terms of spectrum and half-value layers. The change in beam quality due to source to source variation and source aging is significant, and each source should be treated on individual basis.…”

Section: Purposementioning

confidence: 99%

Dosimetric Characteristics of a New Unit for Electronic Skin Brachytherapy

et al. 2014

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Purpose: Brachytherapy with radioactive high dose rate (HDR) 192 Ir source is applied to small skin cancer lesions, using surface applicators, i.e. Leipzig or Valencia type. New developments in the field of radiotherapy for skin cancer include electronic brachytherapy. This technique involves the placement of an HDR X-ray source close to the skin, therefore combining the benefits of brachytherapy with the reduced shielding requirements and targeted energy of low energy X-rays. Recently, the Esteya ® Electronic Brachytherapy System (Esteya EBS, Elekta AB-Nucletron, Stockholm, Sweden) has been developed specifically for HDR brachytherapy treatment of surface lesions. The system provides radionuclide free HDR brachytherapy by means of a small 69.5 kV X-ray source. The purpose of this study is to obtain the dosimetric characterization required for clinical implementation, providing the detailed methodology to perform the commissioning.Material and methods: Flatness, symmetry and penumbra, percentage of depth dose (PDD), kV stability, HVL, output, spectrum, linearity, and leakage have been evaluated for a set of applicators (from 10 mm to 30 mm in diameter).Results: Flatness and symmetry resulted better than 5% with around 1 mm of penumbra. The depth dose gradient is about 7%/mm. A kV value of 68.4 ± 1.0 kV (k = 1) was obtained, in good agreement with manufacturer data (69.5 kV). HVL was 1.85 mm Al. Dose rate for a typical 6 Gy to 7 Gy prescription resulted about 3.3 Gy/min and the leakage value was < 100 µGy/min. Conclusions:The new Esteya ® Electronic Brachytherapy System presents excellent flatness and penumbra as with the Valencia applicator case, combined with an improved PDD, allowing treatment of lesions of up to a depth of 5 mm in combination with reduced treatment duration. The Esteya unit allows HDR brachytherapy superficial treatment within a minimally shielded environment due its low energy.

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Section: Purposementioning

confidence: 99%

Dosimetric Characteristics of a New Unit for Electronic Skin Brachytherapy

et al. 2014

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“…; who measured the HVL at 0.5 ± 0.2 mmAl, using a similar, modified TG‐61 setup 8. Table 2 shows that the attenuation by Tegaderm are all less than 0.4% for the four different methods accounting for changing energy spectrum.…”

Section: Resultsmentioning

confidence: 99%

“…Liu et al. concluded that the change in beam quality due to source variation and source aging is significant and each source should be treated on an individual basis 8. Independent verification and validation of all equipment and software provided by vendor is of upmost importance for accuracy of treatment and patient safety.…”

Section: Introductionmentioning

confidence: 99%

Investigation of a source model for a new electronic brachytherapy tandem by film measurement

Martin

Sowards

Wang

2018

J Applied Clin Med Phys

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PurposeTo investigate the accuracy of a vendor‐supplied source model for a new Xoft Axxent 0‐degree titanium tandem by film measurement.MethodsWe measured the anisotropy factors at varying distances and angles from the tandem in water using radiochromic film (Gafchromic EBT3) and an Epson Perfection v750 desktop flatbed scanner (US Epson, Long Beach, CA). A 0‐degree tandem was placed vertically in a water phantom. Four pieces of film, each at varying depths, were positioned orthogonal to the longitudinal axis of the tandem for azimuthal anisotropy measurements. Polar anisotropy measurements were taken with the film aligned parallel to the tandem. An absolute dose calibration for the film was verified with a PTW 34013 Soft X‐Ray Chamber. The film measurements were analyzed using different color channels. The measured polar anisotropy for varying source positions was compared to the vendor's data. Azimuthal anisotropy was measured as a function of the radius and angle, and normalized to the mean value over all angles at the specified radius.ResultsThe azimuthal anisotropy of the tandem and source was found to be consistent for different positions along the tandem's longitudinal axis and at varying distances from the tandem. Absolute dose using a calibrated parallel plate chamber showed agreement to within 2% of expected TPS values. The custom tandem, which has a thicker tip than the wall, was attenuating the 50 kV photons more than expected, at the angles where the photons had more wall material to traverse. This discrepancy was verified at different distances from the tandem and with different measurement techniques. As distance increased, anisotropy values had better agreement.ConclusionsWe quantified the agreement between the measured and provided anisotropy factors for a new Xoft Axxent 0‐degree titanium tandem. Radiochromic film response at low kV energy was also investigated. Our results showed that vendor‐supplied TG‐43 values were appropriate for clinical use at majority of the angles. A rigorous quality assurance method for new electronic brachytherapy sources and applicators, along with complete knowledge of all dosimetric measuring tools, should be implemented for all parts of the verification and commissioning process.

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“…The 192 Ir spectrum was taken from National Nuclear Data Center (Baglin 2012) and the 50 kV spectrum from Liu et al (2008) using a Geant4 model based on the work of Rivard et al (2006). Additionally, simpler geometries such as a water cube and a spherical APBI applicator were employed for estimation of calculation efficiency and validation.…”

Section: Geometries Of Interestmentioning

confidence: 99%

The use of tetrahedral mesh geometries in Monte Carlo simulation of applicator based brachytherapy dose distributions

et al. 2014

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Accounting for brachytherapy applicator attenuation is part of the recommendations from the recent report of AAPM Task Group 186. To do so, model based dose calculation algorithms require accurate modelling of the applicator geometry. This can be non-trivial in the case of irregularly shaped applicators such as the Fletcher Williamson gynaecological applicator or balloon applicators with possibly irregular shapes employed in accelerated partial breast irradiation (APBI) performed using electronic brachytherapy sources (EBS). While many of these applicators can be modelled using constructive solid geometry (CSG), the latter may be difficult and timeconsuming. Alternatively, these complex geometries can be modelled using tessellated geometries such as tetrahedral meshes (mesh geometries (MG)).

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Spectroscopic characterization of a novel electronic brachytherapy system

Cited by 44 publications

References 24 publications

Dosimetric Characteristics of a New Unit for Electronic Skin Brachytherapy

Dosimetric Characteristics of a New Unit for Electronic Skin Brachytherapy

Investigation of a source model for a new electronic brachytherapy tandem by film measurement

The use of tetrahedral mesh geometries in Monte Carlo simulation of applicator based brachytherapy dose distributions

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