Two-dimensional dosimetry for an electronic brachytherapy source using radiochromic EBT film: Determination of TG43 parameters

Chiu‐Tsao, Sou‐Tung; Davis, Stephen D.; Pike, T; DeWerd, Larry A.; Rusch, Thomas W.; Burnside, R; Chadha, Manjeet; Harrison, Louis B.

doi:10.1016/j.brachy.2007.02.110

Cited by 4 publications

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“…There have been several reports on the dosimetric applications of EBT film in quality assurance of intensity modulated radiation therapy ͑IMRT͒, 23,25 radiosurgery, 26 external photon and electron beam therapy, 27,28 tomotherapy, 23 and brachytherapy applications. [29][30][31][32] With the experience gained in using MD55 films for intravascular brachytherapy dosimetry, we proceeded to study the feasibility of using EBT films to measure the 2D dosimetry for an 125 I seed in Solid Water ® phantom for distances out to 5 cm within a reasonably achievable time frame. We carried out this study using an Implant Sciences model 3500 125 I seed [33][34][35] by measuring two-dimensional dose distributions at distances ͑from the seed center͒ as short as 0.06 cm out to 5 cm.…”

Section: Introductionmentioning

confidence: 99%

The use of new GAFCHROMIC® EBT film for I125 seed dosimetry in Solid Water® phantom

2008

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Radiochromic film dosimetry has been extensively used for intravascular brachytherapy applications for near field within 1 cm from the sources. With the recent introduction of new model of radiochromic films, GAFCHROMIC EBT, with higher sensitivity than earlier models, it is promising to extend the distances out to 5 cm for low dose rate (LDR) source dosimetry. In this study, the use of new model GAFCHROMIC EBT film for 125I seed dosimetry in Solid Water was evaluated for radial distances from 0.06 cm out to 5 cm. A multiple film technique was employed for four 125I seeds (Implant Sciences model 3500) with NIST traceable air kerma strengths. Each experimental film was positioned in contact with a 125I seed in a Solid Water phantom. The products of the air kerma strength and exposure time ranged from 8 to 3158 U-h, with the initial air kerma strength of 6 U in a series of 25 experiments. A set of 25 calibration films each was sequentially exposed to one 125I seed at about 0.58 cm distance for doses from 0.1 to 33 Gy. A CCD camera based microdensitometer, with interchangeable green (520 nm) and red (665 nm) light boxes, was used to scan all the films with 0.2 mm pixel resolution. The dose to each 125I calibration film center was calculated using the air kerma strength of the seed (incorporating decay), exposure time, distance from seed center to film center, and TG43U1S1 recommended dosimetric parameters. Based on the established calibration curve, dose conversion from net optical density was achieved for each light source. The dose rate constant was determined as 0.991 cGy U(-1)h(-1) (+/-6.9%) and 1.014 cGy U(-1)h(-1) (+/-6.8%) from films scanned using green and red light sources, respectively. The difference between these two values was within the uncertainty of the measurement. Radial dose function and 2D anisotropy function were also determined. The results obtained using the two light sources corroborated each other. We found good agreement with the TG43U1S1 recommended values of radial dose function and 2D anisotropy function, to within the uncertainty of the measurement. We also verified the dosimetric parameters in the near field calculated by Rivard using Monte Carlo method. The radial dose function values in Solid Water were lower than those in water recommended by TG43U1S1, by about 2%, 3%, 7%, and 14% at 2, 3, 4, and 5 cm, respectively, partially due to the difference in the phantom material composition. Radiochromic film dosimetry using GAFCHROMIC EBT model is feasible in determining 2D dose distributions around low dose rate 125I seed. It is a viable alternative to TLD dosimetry for 125I seed dose characterization.

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Section: Introductionmentioning

confidence: 99%

The use of new GAFCHROMIC® EBT film for I125 seed dosimetry in Solid Water® phantom

2008

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“…9,[13][14][15] The electronic brachytherapy source produced by Xoft (San Jose, California), for instance, offers a 15-mm long X-ray tube run at 50 kV and 300 µA [11][12][13] that has been reported to achieve 2.5 Gy/min at a distance of 1 cm in water. 16 A study performed by Rivard et al on the TG-43-compliant dosimetry of the Xoft source found spherical symmetry in the dose distribution comparable to that of brachytherapy sources. 17 This was the expressed intention of Xoft and other miniature X-ray tube manufacturers like them.…”

Section: Introductionmentioning

confidence: 96%

“…The consequences of these design priorities have resulted in low‐kilovoltage X‐ray tubes operated at low current with near‐homogeneous fields 9,13–15 . The electronic brachytherapy source produced by Xoft (San Jose, California), for instance, offers a 15‐mm long X‐ray tube run at 50 kV and 300 µA 11–13 that has been reported to achieve 2.5 Gy/min at a distance of 1 cm in water 16 . A study performed by Rivard et al.…”

Section: Introductionmentioning

confidence: 99%

Proof‐of‐concept for a thin conical X‐ray target optimized for intensity and directionality for use in a carbon nanotube‐based compact X‐ray tube

Insley,

Bartkoski,

Balter

et al. 2023

Medical Physics

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BackgroundCarbon nanotube‐based cold cathode technology has revolutionized the miniaturization of X‐ray tubes. However, current applications of these devices required optimization for large, uniform fields with low intensity.PurposeThis work investigated the feasibility and radiological characteristics of a novel conical X‐ray target optimized for high intensity and high directionality to be used in a compact X‐ray tube.MethodsThe proposed device uses an ultrathin, conical tungsten‐diamond target that exhibits significant heat loading while maintaining a small focal spot size and promoting forward‐directedness of the X‐ray field through preferential attenuation of oblique‐angled photons. The electrostatic and thermal properties of the theoretical tube were calculated and analyzed using COMSOL Multiphysics software. The production, transport, and calculation of radiological properties associated with the resultant X‐ray field were performed using the Geant4 toolkit via its wrapper, TOPAS.ResultsHeat transfer analysis of this X‐ray tube demonstrated the feasibility of a 200‐kV electron beam bombarding the proposed target at a maximum current of 100 mA using a 1‐ms symmetric duty cycle. The cathode of the X‐ray tube was designed to be segmented into nine switchable electrical segments for modulation of the focal spot size from 0.4‐ to 10.8‐mm. After importing the COMSOL‐derived electron beam into TOPAS for X‐ray production simulations, radiological analysis of the resultant field demonstrated high levels of intrinsic beam collimation while maintaining high intensity. A maximum dose rate of 17,887 cGy/min was calculated for 1‐mm depth in water at 7‐cm distance.ConclusionsThe proposed X‐ray tube design can create highly directional X‐ray fields with superior fluence compared to that of current commercial X‐ray tubes of comparable size.

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“…Companies like Carl Zeiss (Oberkoche, Germany, INTRABEAM) [ 16 , 17 ] and Xoft (Fremont, Axxent C.A.) [ 18 - 20 ] and ELEKTA, (Stockholm, Sweden, Esteya) [ 21 ] have designed eBS systems to treat tumors. The eBS system was designed in 1996 by photoelectron company (INTRABEAM).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Effect of Source Geometry on the Output of Miniature X-ray Tube for Electronic Brachytherapy through Simulation

et al. 2018

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Objective: The use of miniature X-ray source in electronic brachytherapy is on the rise so there is an urgent need to acquire more knowledge on X-ray spectrum production and distribution by a dose. The aim of this research was to investigate the influence of target thickness and geometry at the source of miniature X-ray tube on tube output. Method:Five sources were simulated based on problems each with a specific geometric structure and conditions using MCNPX code. Tallies proportional to the output were used to calculate the results for the influence of source geometry on output. Results:The results of this work include the size of the optimal thickness of 5 miniature sources, energy spectrum of the sources per 50 kev and also the axial and transverse dose of simulated sources were calculated based on these thicknesses. The miniature source geometric was affected on the output x-ray tube. Conclusion:The result of this study demonstrates that hemispherical-conical, hemispherical and truncated-conical miniature sources were determined as the most suitable tools.

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Two-dimensional dosimetry for an electronic brachytherapy source using radiochromic EBT film: Determination of TG43 parameters

Cited by 4 publications

References 0 publications

The use of new GAFCHROMIC® EBT film for I125 seed dosimetry in Solid Water® phantom

The use of new GAFCHROMIC® EBT film for I125 seed dosimetry in Solid Water® phantom

Proof‐of‐concept for a thin conical X‐ray target optimized for intensity and directionality for use in a carbon nanotube‐based compact X‐ray tube

Evaluation of the Effect of Source Geometry on the Output of Miniature X-ray Tube for Electronic Brachytherapy through Simulation

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