The measurement of inherent filtration in diagnostic X-ray tubes and the effect of target angle on X-ray quality

Ardran, G. M.; Crooks, H. E.

doi:10.1259/0007-1285-45-536-599

Cited by 6 publications

(3 citation statements)

References 7 publications

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“…The condition of the anode surface and the deposition of sputtered tungsten on the tube envelope have also been made responsible for an increased effective inherent filtration (see e.g. Ardran and Crooks (1972)). Tungsten deposits on the inner side of the tube are found to be much less than 1 µm in thickness (Stears et al 1986, Nagel 1988) and consequently should give little contribution to attenuation.…”

Section: Introductionmentioning

confidence: 99%

Simulation of the effect of anode surface roughness on diagnostic x-ray spectra

Nowotny

Meghzifene²

2002

Phys. Med. Biol.

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To simulate the effect of the condition of the anode surface on x-ray output the surface roughness of anode fragments of replaced clinical x-ray tubes was determined. A mean roughness of 1.32-5.22 microm giving effective tungsten absorption layers of up to 18 microm thickness in the direction of the x-ray beam was determined. X-ray spectra were then simulated using the measured surface profiles. The most prominent effect was the reduction of the kerma output of the tube with increasing roughness (-33% at 50 kV tube voltage and 5 microm roughness). The effects of beam hardening are less pronounced. The corresponding changes in the spectral parameters are generally small but largest for tube voltages up to 70 kV. For higher voltages the increased photon attenuation above the K-edge of tungsten reduces the effects of roughness on spectral parameters. The maximum shifts in mean photon energy of about 1 keV and in HVL of about 0.2 mm Al were obtained for an anode roughness of 5 microm.

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Section: Introductionmentioning

confidence: 99%

Simulation of the effect of anode surface roughness on diagnostic x-ray spectra

Nowotny

Meghzifene²

2002

Phys. Med. Biol.

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“…As a direct measurement of the total filtration of the x-ray tube assemblies is not feasible, various indirect methods for its determination have been proposed and its limitations discussed (see e.g. Ardran and Crooks (1972), Sutcliffe (1983) and Nagel (1988)). In most methods, a relationship for inherent filtration and HVL of the x-ray beam for a typical x-ray device is established and then used for the determination of inherent filtration (quality diagrams).…”

Section: Introductionmentioning

confidence: 99%

A fit method for the determination of inherent filtration with diagnostic x-ray units

2006

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A method for the determination of total inherent filtration for clinical x-ray units using attenuation curves was devised. A model for the calculation of x-ray spectra is used to calculate kerma values which are then adjusted to the experimental data in minimizing the sum of the squared relative differences in kerma using a modified simplex fit process. The model considers tube voltage, voltage ripple, anode angle and additional filters. Fit parameters are the thickness of an additional inherent Al filter and a general normalization factor. Nineteen sets of measurements including attenuation data for three tube voltages and five Al-filter settings each were obtained. Relative differences of experimental and calculated kerma using the data for the additional filter thickness are within a range of -7.6% to 6.4%. Quality curves, i.e. the relationship of additional filtration to HVL, are often used to determine filtration but the results show that standard quality curves do not reflect the variety of conditions encountered in practice. To relate the thickness of the additional filter to the condition of the anode surface, the data fits were also made using tungsten as the filter material. These fits gave an identical fit quality compared to aluminium with a tungsten filter thickness of 2.12-8.21 microm which is within the range of the additional absorbing layers determined for rough anodes.

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“…There is recognition in the literature of various factors affecting the accuracy of H V L and hence total-filtration assessment, e.g. purity of aluminium filters (Jones 1961), geometry and minimisation of scatter (Trout et a1 1960a), quality response of the dosemeter (Johns andCunningham 1983, Nagel 1988), kilovoltage ripple (Trout er a1 1960b), target angle (Ardran and Crooks 1972) and the requirement for use of HvL-totalfiltration data appropriate to the condition of measurements (Birch et al 1979). More 0031-9155/90/070999+ 17303.50 @ 1990 IOP Publishing Ltd recently Nagel (1988) has also investigated the influence of tube aging and composition of the filter.…”

Section: Introductionmentioning

confidence: 99%

Errors in the determination of total filtration of diagnostic X-ray tubes by the HVL method

Gilmore¹,

Cranley²

1990

Phys. Med. Biol.

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There are many sources of error in the traditional method involving measurement of the half-value layer (HVL) and use of appropriate conversion data to determine the total filtration of X-ray tube assemblies. Optimal technique and an analysis of errors are essential for interpreting whether the total filtration of a diagnostic X-ray tube is acceptable. This study approaches these problems from a theoretical viewpoint utilising recent theoretical HVL-total-filtration data relating to 10' and 16' tungsten target angles and 0-30% kilovoltage ripples. The theory indicates the typical accuracy to which each of the appropriate parameters must be determined to maintain acceptable errors in total filtration. A quantitative approach is taken to evaluate systematic errors in a technique for interpolation of HVL from raw attenuation curve data.

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The measurement of inherent filtration in diagnostic X-ray tubes and the effect of target angle on X-ray quality

Cited by 6 publications

References 7 publications

Simulation of the effect of anode surface roughness on diagnostic x-ray spectra

Simulation of the effect of anode surface roughness on diagnostic x-ray spectra

A fit method for the determination of inherent filtration with diagnostic x-ray units

Errors in the determination of total filtration of diagnostic X-ray tubes by the HVL method

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