Pantak Therapax SXT 150: performance assessment and dose determination using IAEA TRS-398 protocol

Jurado, Dolores; Eudaldo, T.; Carrasco, P.; Jornet, N.; Ruiz, A.; Ribas, M.

doi:10.1259/bjr/15782649

Cited by 17 publications

(23 citation statements)

References 4 publications

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“…Jurado et al [12] evaluated the Therapax SXT 150 unit, which encompass both low and medium-energy beams. The timer error was significant for all filters and should be taken into consideration for absorbed dose rate determination under reference conditions, as well as for the calculation of treatment times.…”

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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“…The film was placed vertically in a water phantom to measure the dose at any depth along the beam central axis. PDD measurements were further compared with the data from Jurado et al 30 who used a PTW chamber. Monte Carlo simulations performed using the EGSnrc/DOSRZnrc code 28 were considered as the reference data for comparison purposes.…”

Section: Iie2 Percent Depth Dose (Pdd) Measurementsmentioning

confidence: 99%

“…17.1 ± 0.2 42.0 ± 1.0 38.3 ± 0.9 37.4 ± 1.0 38.9 ± 0.6 36.9 ± 0.8 44 20.9 ± 0.2 41.0 ± 0.9 37.6 ± 0.9 36.6 ± 0.9 38.1 ± 0.7 36.2 ± 0.8 59 26.6 ± 0.3 38.0 ± 0.9 38.4 ± 1.0 37.7 ± 1.0 38.4 ± 0.9 37.4 ± 0.9 86 34.9 ± 0.3 37.8 ± 0.9 40.1 ± 0.9 39.9 ± 0.9 39.5 ± 0.8 39. effect, reducing the difference to 3%. The data from Jurado et al 30 lie between the PSD raw data and the PSD corrected data. It is important to specify that PDD from Jurado et al that are illustrated in Fig.…”

Section: Iiid Pdd Measurementsmentioning

confidence: 99%

Validating plastic scintillation detectors for photon dosimetry in the radiologic energy range

et al. 2012

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Purpose: Photon dosimetry in the kilovolt (kV) energy range represents a major challenge for diagnostic and interventional radiology and superficial therapy. Plastic scintillation detectors (PSDs) are potentially good candidates for this task. This study proposes a simple way to obtain accurate correction factors to compensate for the response of PSDs to photon energies between 80 and 150 kVp. The performance of PSDs is also investigated to determine their potential usefulness in the diagnostic energy range. Methods: A 1-mm-diameter, 10-mm-long PSD was irradiated by a Therapax SXT 150 unit using five different beam qualities made of tube potentials ranging from 80 to 150 kVp and filtration thickness ranging from 0.8 to 0.2 mmAl + 1.0 mmCu. The light emitted by the detector was collected using an 8-m-long optical fiber and a polychromatic photodiode, which converted the scintillation photons to an electrical current. The PSD response was compared with the reference free air dose rate measured with a calibrated Farmer NE2571 ionization chamber. PSD measurements were corrected using spectra-weighted corrections, accounting for mass energy-absorption coefficient differences between the sensitive volumes of the ionization chamber and the PSD, as suggested by large cavity theory (LCT). Beam spectra were obtained from x-ray simulation software and validated experimentally using a CdTe spectrometer. Correction factors were also obtained using Monte Carlo (MC) simulations. Percent depth dose (PDD) measurements were compensated for beam hardening using the LCT correction method. These PDD measurements were compared with uncorrected PSD data, PDD measurements obtained using Gafchromic films, Monte Carlo simulations, and previous data. Results: For each beam quality used, the authors observed an increase of the energy response with effective energy when no correction was applied to the PSD response. Using the LCT correction, the PSD response was almost energy independent, with a residual 2.1% coefficient of variation (COV) over the 80-150-kVp energy range. Monte Carlo corrections reduced the COV to 1.4% over this energy range. All PDD measurements were in good agreement with one another except for the uncorrected PSD data, in which an over-response was observed with depth (13% at 10 cm with a 100 kVp beam), showing that beam hardening had a non-negligible effect on the PSD response. A correction based on LCT compensated very well for this effect, reducing the over-response to 3%. Conclusion: In the diagnostic energy range, PSDs show high-energy dependence, which can be corrected using spectra-weighted mass energy-absorption coefficients, showing no considerable sign of quenching between these energies. Correction factors obtained by Monte Carlo simulations confirm that the approximations made by LCT corrections are valid. Thus, PSDs could be useful for realtime dosimetry in radiology applications.

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“…It is important that data used for treatment are determined in water or in a water-equivalent medium or that the irradiated medium is stated for data given in publications. 14,15 This article reports on the acceptance and commissioning work carried out on the T-200 X-ray therapy system manufactured by Wolf-Medizintechnik (WOmed) GmbH (WOmed, St Gangloff, Germany) installed at our clinic. The intended use of this machine is for superficial X-ray therapy using beams from tube potentials between 30 and 200 kV.…”

Section: Introductionmentioning

confidence: 99%

“…The intended use of this machine is for superficial X-ray therapy using beams from tube potentials between 30 and 200 kV. Existing publications 14,[16][17][18] report on performance characteristics and dose determination from kV units by other manufacturers. The T-200 system by WOmed differs from other systems, because of its design using interchangeable filters on a carousel, the design of its applicators and the integrated software for machine control and clinical use.…”

Section: Introductionmentioning

confidence: 99%

Acceptance, commissioning and clinical use of the WOmed T-200 kilovoltage X-ray therapy unit

Aspradakis¹,

Zucchetti²

2015

BJR

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Objective: The objective of this work was to characterize the performance of the WOmed T-200-kilovoltage (kV) therapy machine. Methods: Mechanical functionality, radiation leakage, alignment and interlocks were investigated. Half-value layers (HVLs) (first and second HVLs) from X-ray beams generated from tube potentials between 30 and 200 kV were measured. Reference dose was determined in water. Beam start-up characteristics, dose linearity and reproducibility, beam flatness, and uniformity as well as deviations from inverse square law were assessed. Relative depth doses (RDDs) were determined in water and water-equivalent plastic. The quality assurance program included a dosimetry audit with thermoluminescent dosemeters. Results: All checks on machine performance were satisfactory. HVLs ranged between 0.45-4.52 mmAl and 0.69-1.78 mmCu. Dose rates varied between 0.2 and 3 Gy min 21 with negligible time-end errors. There were differences in measured RDDs from published data. Beam outputs were confirmed with the dosimetry audit. The use of published backscatter factors was implemented to account for changes in phantom scatter for treatments with irregularly shaped fields. Conclusion: Guidance on the determination of HVL and RDD in kV beams can be contradictory. RDDs were determined through measurement and curve fitting. These differed from published RDD data, and the differences observed were larger in the low-kV energy range. Advances in knowledge: This article reports on the comprehensive and novel approach to the acceptance, commissioning and clinical use of a modern kV therapy machine. The challenges in the dosimetry of kV beams faced by the medical physicist in the clinic are highlighted.

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Pantak Therapax SXT 150: performance assessment and dose determination using IAEA TRS-398 protocol

Cited by 17 publications

References 4 publications

Dosimetric Characteristics of a New Unit for Electronic Skin Brachytherapy

Dosimetric Characteristics of a New Unit for Electronic Skin Brachytherapy

Validating plastic scintillation detectors for photon dosimetry in the radiologic energy range

Acceptance, commissioning and clinical use of the WOmed T-200 kilovoltage X-ray therapy unit

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