Rapid Computation of Diagnostic X-Ray Bremsstrahlung Spectra

Stanton, Leonard; Day, John; Lightfoot, David A.; Villafana, Theodore; Rauch, Philip L.

doi:10.1148/130.2.477

Cited by 10 publications

(5 citation statements)

References 8 publications

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“…However, when using any of the different spectral models developed over the years, there is a concern that they are based on limited measurements made with machines operated in configurations that are atypical of the current clinical situation (e.g. they used low tube currents, older glass-windowed tubes) (Stanton et al 1979, Birch and Marshall 1979, Kodera et al 1983, Tucker et al 1991b.…”

Section: Introductionmentioning

confidence: 99%

A comparison of mammography spectral measurements with spectra produced using several different mathematical models

2001

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Due to the relatively complex nature of spectral measurements from x-ray machines, many researchers use mathematical models to simulate the spectra they need. However, there is concern over their accuracy, and hence the impact that their accuracy may have, on subsequent calculations that rely upon the spectra modelled. With this in mind spectral measurements have been performed on a mammography machine and a comparison with spectra calculated using several different models is presented. Several different techniques have been investigated in the spectral measurements to allow for pulse pileup and other effects of high count rate. Comparison with half value layer (HVL) measurements shows that the use of a gating signal in conjunction with the air-free path provides accurate results without the need for a pinhole collimator. Comparison of the measured spectra with those calculated using different models proposed in the literature suggests that accurate results can be produced by all models, but only if the user attempts to match the calculated HVL of the modelled spectrum with the physically measured HVL. If this is not done the modelled spectra may be in error. The impact of such an error is demonstrated in calculations of mean glandular dose, which indicate a possible underestimate of the dose by up to 20%.

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Section: Introductionmentioning

confidence: 99%

A comparison of mammography spectral measurements with spectra produced using several different mathematical models

2001

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“…Shown are normalized spectra E +(E) p,,(E)lp, where b,,(E)lp is the mass-energy absorption coefficient at photon energy E; this representation is such that the area under the curves delimited by any two photon energies is approximately proportional to the fraction of dose deposited by photons in that energy range. Solid line: 80 kVp X rays from a tungsten target, typical of those used in fluoroscopic examinations given to tuberculosis patients (14)(15)(16). Also shown are photon spectra incident on survivors at Hiroshima (short dash, ground distance 1.5 km) and Nagasaki (long dash, ground distance 1.9 km).…”

Section: Nagasaki---l'--;----mentioning

confidence: 99%

Does Fractionation Decrease the Risk of Breast Cancer Induced by Low-LET Radiation?

Brenner

1999

Radiation Research

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Whether fractionation decreases the risk of breast cancer induced by low-LET radiation is a question of some importance. Analyses of the data for TB cohorts who were exposed to multiple fluoroscopies show an apparently similar breast cancer risk compared with those for the acutely exposed A-bomb survivors. However, the fluoroscopy cohorts were subjected to very much lower-energy photons (60-80 kVp) compared with the A-bomb survivors; the increased RBE associated with the low photon energies to which these fluoroscopy cohorts were exposed suggests that, in comparison to the risk estimates for the A-bomb survivors, the risk estimates from the X-ray fluoroscopy cohorts are increased because of the lower-energy X rays and decreased by a similar amount due to fractionation, resulting in an overall apparent equality of risk. Thus the results from the most powerful epidemiological data sets available for assessing breast cancer risks after fractionated exposure to low-LET radiation (the fluoroscopy cohorts) are quite consistent with a lower radiation risk for a fractionated exposure in comparison to an acute exposure. In general, for any cancer site, estimates of the dose-rate effectiveness factor (DDREF) generated by comparing the results for A-bomb survivors with those for the TB fluoroscopy cohorts should probably be roughly doubled from their apparent values because of the increased RBE of the fluoroscopy X rays.

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“…There were only a few attempts to take into account the effects of pulsation with the aid of weighted averaging of spectra approximated by Kramers' formula. Stanton et al (1979) have fitted Kramers' spectra by empirical factors to measured values before averaging. presented pulsatingpotential x-ray spectra calculated by averaging theoretical spectra fitted to some experimental data, and also included the attenuation due to inherent filtration and air path.…”

Section: Preliminariesmentioning

confidence: 99%

Calculations concerning voltage ripple of X-ray generators

Porubszky¹

1986

Phys. Med. Biol.

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Formulae are given for absorbed dose, fluence and energy fluence of narrow x-ray beams generated by pulsatingpotential x-ray generators with any waveform. A computer program has been written for calculating these and some other quantities, including mean energies, for particular waveforms. A new definition is suggested for the ripple correction factor of pulsating-potential x-ray generators for the assessment of their performance. Some numerical results and applications are discussed.

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Rapid Computation of Diagnostic X-Ray Bremsstrahlung Spectra

Cited by 10 publications

References 8 publications

A comparison of mammography spectral measurements with spectra produced using several different mathematical models

A comparison of mammography spectral measurements with spectra produced using several different mathematical models

Does Fractionation Decrease the Risk of Breast Cancer Induced by Low-LET Radiation?

Calculations concerning voltage ripple of X-ray generators

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