Computation of bremsstrahlung X-ray spectra and comparison with spectra measured with a Ge(Li) detector

Birch, Rolf B.; Marshall, M

doi:10.1088/0031-9155/24/3/002

Cited by 470 publications

(254 citation statements)

References 23 publications

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“…MOSFET sensitivities were assessed using two different filter combinations (2.5 mm Al, and

2.5 mm Al + 0.5 mm Cu

) to reproduce two different commonly used dental energy spectra. The X‐ray spectra, expressed in terms of the half value layer (HVL) and the average photon energy (Table 1) were calculated using a computer program (23) that was based on the semi‐empirical spectrum model described by Birch and Marshall (24) …”

Section: Methodsmentioning

confidence: 99%

Characterization of MOSFET dosimeters for low‐dose measurements in maxillofacial anthropomorphic phantoms

Koivisto

Wolff

Kiljunen

et al. 2015

J Applied Clin Med Phys

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The aims of this study were to characterize reinforced metal‐oxide‐semiconductor field‐effect transistor (MOSFET) dosimeters to assess the measurement uncertainty, single exposure low‐dose limit with acceptable accuracy, and the number of exposures required to attain the corresponding limit of the thermoluminescent dosimeters (TLD). The second aim was to characterize MOSFET dosimeter sensitivities for two dental photon energy ranges, dose dependency, dose rate dependency, and accumulated dose dependency. A further aim was to compare the performance of MOSFETs with those of TLDs in an anthropomorphic phantom head using a dentomaxillofacial CBCT device. The uncertainty was assessed by exposing 20 MOSFETs and a Barracuda MPD reference dosimeter. The MOSFET dosimeter sensitivities were evaluated for two photon energy ranges (50–90 kVp) using a constant dose and polymethylmethacrylate backscatter material. MOSFET and TLD comparative point‐dose measurements were performed on an anthropomorphic phantom that was exposed with a clinical CBCT protocol. The MOSFET single exposure low dose limit (25% uncertainty, normalk=2) was 1.69 mGy. An averaging of eight MOSFET exposures was required to attain the corresponding TLD (0.3 mGy) low‐dose limit. The sensitivity was 3.09±0.13 mV/mGy independently of the photon energy used. The MOSFET dosimeters did not present dose or dose rate sensitivity but, however, presented a 1% decrease of sensitivity per 1000 mV for accumulated threshold voltages between 8300 mV and 17500 mV. The point doses in an anthropomorphic phantom ranged for MOSFETs between 0.24 mGy and 2.29 mGy and for TLDs between 0.25 and 2.09 mGy, respectively. The mean difference was −8%. The MOSFET dosimeters presented statistically insignificant energy dependency. By averaging multiple exposures, the MOSFET dosimeters can achieve a TLD‐comparable low‐dose limit and constitute a feasible method for diagnostic dosimetry using anthropomorphic phantoms. However, for single in vivo measurements (<1.7 mGy) the sensitivity is too low.PACS number: 87.50.wj

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“…MOSFET sensitivities were assessed using two different filter combinations (2.5 mm Al, and

2.5 mm Al + 0.5 mm Cu

Section: Methodsmentioning

confidence: 99%

Characterization of MOSFET dosimeters for low‐dose measurements in maxillofacial anthropomorphic phantoms

Koivisto

Wolff

Kiljunen

et al. 2015

J Applied Clin Med Phys

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“…For the 120 kV setting, a 9 mm aluminum plate directly positioned above the window and a 1 mm aluminum plate holding the samples were used for filtering. This setup provided an X-ray bremsstrahlung-spectrum with photon energies from ~30 to 120 keV and a predominant characteristic X-ray peak at ~60 keV (14). For the 25 kV setting, only a plate holding the samples (0.5 mm aluminum) was used, providing a bremsstrahlung-spectrum from ~8 to 25 keV with an intensity maximum at ~15 keV and no significant characteristic X-ray peak (15).…”

Section: Irradiation and Dosimetrymentioning

confidence: 99%

X-irradiation of cells on glass slides has a dose doubling impact

et al. 2007

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Immunofluorescence detection of γH2AX foci is a widely used tool to quantify the induction and repair of DNA double-strand breaks induced by ionising radiation. We observed that Xirradiation of mammalian cells exposed on glass slides induced 2-fold higher foci numbers compared to irradiation with γ-rays. Here, we show that the excess γH2AX foci after Xirradiation are produced from secondary radiation particles generated from the irradiation of glass slides. Both 120 kV X-rays and 137 Cs γ-rays induce ~20 γH2AX foci per Gy in cells growing on thin (~2 µm) plastic foils immersed in water. The same yield is obtained following γ-irradiation of cells growing on glass slides. However, 120 kV X-rays produce ~40 γH2AX foci per Gy in cells growing on glass, two-fold greater than obtained using cells irradiated on plastic surfaces. The same increase in γH2AX foci number is obtained if the plastic foil on which the cells are grown is irradiated on a glass slide. Thus, the physical proximity to the glass material and not morphological differences of cells growing on different surfaces accounts for the excess γH2AX foci. The increase in foci number depends on the energy and is considerably smaller for 25 kV relative to 120 kV X-rays, a finding which can be explained by known physical properties of radiation. The kinetics for the loss of foci, which is taken to represent the rate of DSB repair, as well as the Artemis dependent repair fraction, was similar following X-or γ-irradiation, demonstrating that DSBs induced by this range of treatments are repaired in an identical manner.3

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“…X-ray energy spectra for the simulation were generated using the semi empirical model of Birch and Marshall [5], using an x-ray tube operating in a 30 to 90 kVp interval, a W target and 1.0 mm Al filtration. Highly collimated x-ray beams (pencil beam) were assumed following a linear trajectory at each angular interval, covering a total angle of 180º (half-scan) or 360º (full-scan).…”

Section: Methodsmentioning

confidence: 99%

Monte Carlo simulation of an x-ray luminescence optical tomography scanner prototype

Rosas-González

Martínez‐Dávalos

Rodríguez‐Villafuerte³

et al. 2014

AIP Conference Proceedings

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Abstract. In this work we report the calculation of the deposited energy distribution produced by an x-ray luminescence optical tomography (XLOT) system in a phantom containing different concentrations of Gd 2 O 2 S:Eu nanoparticles. The calculations were performed via Monte Carlo simulation considering spectra from a W target x-ray tube operating between 30 and 90 kVp, with 1.0 mm Al added filtration. CT and XLOT tomographic images were reconstructed from the same data. The results show that XLOT has better detectability than CT alone, that the dose scales linearly with kVp for a fixed concentration of Gd 2 O 2 S:Eu and air-kerma rate, the scattered radiation contribution to the total dose and signal is about 20% and that the dose ratio for a 3 mm diameter insert containing 10 mg/ml Gd 2 O 2 S embedded in a 30 mm diameter water phantom is 6:1. This ratio drops to less than 2:1 for a 1 mg/ml concentration. Finally we show that the method of conjugate images can be used to correct for artifacts due to attenuation effects in XLOT images.

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Computation of bremsstrahlung X-ray spectra and comparison with spectra measured with a Ge(Li) detector

Cited by 470 publications

References 23 publications

Characterization of MOSFET dosimeters for low‐dose measurements in maxillofacial anthropomorphic phantoms

Characterization of MOSFET dosimeters for low‐dose measurements in maxillofacial anthropomorphic phantoms

X-irradiation of cells on glass slides has a dose doubling impact

Monte Carlo simulation of an x-ray luminescence optical tomography scanner prototype

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