Determination of the energy fluence of diagnostic x‐ray beams from field measurements of attenuation curves

Delgado, V.; Ortiz, P.

doi:10.1118/1.598080

Cited by 8 publications

(17 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Ideally, the x-ray beam’s width should be collimated as tightly as possible to the dosimeter as observed previously (Delgado and Ortiz, 1997). Maximizing the AAF diameter by fixing plates to the gantry reduces scatter and eliminates the need for an external fixture.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Real-time dosimeter employed to evaluate the half-value layer in CT

et al. 2013

View full text Add to dashboard Cite

Half-value layer (HVL) measurements on commercial whole body CT scanners require serial measurements and, in many institutions, the presence of a service engineer. An assembly of aluminum filters (AAF), designed to be used in conjunction with a real-time dosimeter, was developed to provide estimates of the HVL using clinical protocols. Two real-time dose probes, a solid-state and air ionization chamber, were examined. The AAF consisted of eight rectangular filters of high purity aluminum (Type 1100), symmetrically positioned to form a cylindrical “cage” around the probe’s detective volume. The incident x-ray beam was attenuated by varying thicknesses of aluminum filters as the gantry completed a minimum of one rotation. Measurements employing real-time chambers were conducted both in service mode and with a routine abdomen/pelvis protocol for several combinations of x-ray tube potentials and bow tie filters. These measurements were validated against conventional serial HVL measurements. The average relative difference between the HVL measurements using the two methods was less than 5% when using a 122 mm diameter AAF; relative differences were reduced to 1.1% when the diameter was increased to 505 mm, possibly due to a reduced scatter contamination. Use of a real-time dose probe and the AAF allowed for time-efficient measurements of beam quality on a clinical CT scanner using clinical protocols.

show abstract

Section: Discussionmentioning

confidence: 99%

“…Extensive work has shown that transmission measurements, such as those used to calculate the half value layer (HVL), adequately characterize the absorption properties of a diagnostic x-ray beam (Bell, 1936; Boone, 1986; Delgado and Ortiz, 1997; Greening, 1963; Kaye, 1934; Poirier et al ; Ruth and Joseph, 1997; Silberstein, 1932). …”

Section: Introductionmentioning

confidence: 99%

Real-time dosimeter employed to evaluate the half-value layer in CT

et al. 2013

View full text Add to dashboard Cite

show abstract

“…In this way, the author has proposed and exploited a method that considers the attenuation curve in itself as a functional description of the x-ray beam. [31][32][33][34][35] This method is well suited to the calculation, in a stable way, of radiometric and dosimetric quantities, and, in general, of generalized moments of the spectral distribution, along the lines presented in Zahrt's book. 30 The aim of the present work is to check the feasibility of an inversion method for the Laplace transform, with the a priori conditions that the solution has to be positive and that its support has to be bounded to a fixed energy range.…”

Section: Introductionmentioning

confidence: 99%

Determination of x‐ray spectra from attenuation data by imposing a priori positiveness and bounded support: Theory and experimental validation

Delgado

2007

Medical Physics

View full text Add to dashboard Cite

The determination of the spectral distribution of an x-ray beam from attenuation measurements in a narrow beam has aroused great interest since it was first proposed by Silberstein in 1932. Since then, it has become clear that this is an ill-conditioned problem. Then, due to the intrinsic difficulties of the problem, care has been taken to improve the mathematical and numerical inversion techniques. Alternative ways to circumvent the explicit inversion by using the attenuation curve itself to calculate directly generalized moments of the solution have also been found. In this work, the explicit reconstruction of the spectral distribution is carried out by an expectation-maximization method that satisfies the a priori condition of positiveness of the solution and allows us to impose the boundness of its support easily, conditions which are known to be fulfilled by physically acceptable solutions. The simulations made and the experimental validation of the proposed method allow us to prove its scope and limitations.

show abstract

“…A validação experimental foi feita através da comparação entre fluência em energia calculada a partir do espectro reconstruído e fluência em energia calculada a partir da curva de transmissão [21] .…”

Section: Validaçãounclassified

“…Onde a,b,c, d e e são parâmetros dados na literatura [21] , com a -0.174 66 [m 2 /kg As fluências em energia foram comparadas e assim dada a validação.…”

Section: Validaçãounclassified

Reconstrução espectral de feixes de raios X diagnósticos

Souza¹

View full text Add to dashboard Cite

Determination of the energy fluence of diagnostic x‐ray beams from field measurements of attenuation curves

Cited by 8 publications

References 22 publications

Real-time dosimeter employed to evaluate the half-value layer in CT

Real-time dosimeter employed to evaluate the half-value layer in CT

Determination of x‐ray spectra from attenuation data by imposing a priori positiveness and bounded support: Theory and experimental validation

Reconstrução espectral de feixes de raios X diagnósticos

Contact Info

Product

Resources

About