Mammographic x-ray unit kilovoltage test tool based on k-edge absorption effect

Mary E. Napolitano, Jon H. Trueblood, Nolan E. Hertel, George David

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

A simple tool to determine the peak kilovoltage (kVp) of a mammographic x-ray unit has been designed. Tool design is based on comparing the effect of k-edge discontinuity of the attenuation coefficient for a series of element filters. Compatibility with the mammography accreditation phantom (MAP) to obtain a single quality control film is a second design objective. When the attenuation of a series of sequential elements is studied simultaneously, differences in the absorption characteristics due to the k-edge discontinuities are more evident. Specifically, when the incident photon energy is higher than the k-edge energy of a number of the elements and lower than the remainder, an inflection may be seen in the resulting attenuation data. The maximum energy of the incident photon spectra may be determined based on this inflection point for a series of element filters. Monte Carlo photon transport analysis was used to estimate the photon transmission probabilities for each of the sequential k-edge filter elements. The photon transmission corresponds directly to optical density recorded on mammographic x-ray film. To observe the inflection, the element filters chosen must have k-edge energies that span a range greater than the expected range of the end point energies to be determined. For the design, incident x-ray spectra ranging from 25 to 40 kVp were assumed to be from a molybdenum target. Over this range, the k-edge energy changes by approximately 1.5 keV between sequential elements. For this design 21 elements spanning an energy range from 20 to 50 keV were chosen. Optimum filter element thicknesses were calculated to maximize attenuation differences at the k-edge while maintaining optical densities between 0.10 and 3.00. Calculated relative transmission data show that the kVp could be determined to within ± 1 kV. To obtain experimental data, a phantom was constructed containing 21 different elements placed in an acrylic holder. MAP images were used to determine appropriate exposure techniques for a series of end point energies from 25 to 35 kVp. The average difference between the kVp determination and the calibrated dial setting was 0.8 and 1.0 kV for a Senographe 600 T and a Senographe DMR, respectively. Since the k-edge absorption energies of the filter materials are well known, independent calibration or a series of calibration curves is not required.

Original languageEnglish (US)
Pages (from-to)2169-2176
Number of pages8
JournalMedical Physics
Volume29
Issue number9
DOIs
StatePublished - Jan 1 2002

Fingerprint

Photons
X-Rays
Accreditation
Mammography
Calibration
Molybdenum
Motion Pictures
Quality Control

Keywords

  • Kilovoltage
  • kVp
  • Mammography
  • Quality control

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging

Cite this

Mammographic x-ray unit kilovoltage test tool based on k-edge absorption effect. / Napolitano, Mary E.; Trueblood, Jon H.; Hertel, Nolan E.; David, George.

In: Medical Physics, Vol. 29, No. 9, 01.01.2002, p. 2169-2176.

Research output: Contribution to journalArticle

Napolitano, Mary E. ; Trueblood, Jon H. ; Hertel, Nolan E. ; David, George. / Mammographic x-ray unit kilovoltage test tool based on k-edge absorption effect. In: Medical Physics. 2002 ; Vol. 29, No. 9. pp. 2169-2176.
@article{4ead7bc789274260b2f848b4887c5765,
title = "Mammographic x-ray unit kilovoltage test tool based on k-edge absorption effect",
abstract = "A simple tool to determine the peak kilovoltage (kVp) of a mammographic x-ray unit has been designed. Tool design is based on comparing the effect of k-edge discontinuity of the attenuation coefficient for a series of element filters. Compatibility with the mammography accreditation phantom (MAP) to obtain a single quality control film is a second design objective. When the attenuation of a series of sequential elements is studied simultaneously, differences in the absorption characteristics due to the k-edge discontinuities are more evident. Specifically, when the incident photon energy is higher than the k-edge energy of a number of the elements and lower than the remainder, an inflection may be seen in the resulting attenuation data. The maximum energy of the incident photon spectra may be determined based on this inflection point for a series of element filters. Monte Carlo photon transport analysis was used to estimate the photon transmission probabilities for each of the sequential k-edge filter elements. The photon transmission corresponds directly to optical density recorded on mammographic x-ray film. To observe the inflection, the element filters chosen must have k-edge energies that span a range greater than the expected range of the end point energies to be determined. For the design, incident x-ray spectra ranging from 25 to 40 kVp were assumed to be from a molybdenum target. Over this range, the k-edge energy changes by approximately 1.5 keV between sequential elements. For this design 21 elements spanning an energy range from 20 to 50 keV were chosen. Optimum filter element thicknesses were calculated to maximize attenuation differences at the k-edge while maintaining optical densities between 0.10 and 3.00. Calculated relative transmission data show that the kVp could be determined to within ± 1 kV. To obtain experimental data, a phantom was constructed containing 21 different elements placed in an acrylic holder. MAP images were used to determine appropriate exposure techniques for a series of end point energies from 25 to 35 kVp. The average difference between the kVp determination and the calibrated dial setting was 0.8 and 1.0 kV for a Senographe 600 T and a Senographe DMR, respectively. Since the k-edge absorption energies of the filter materials are well known, independent calibration or a series of calibration curves is not required.",
keywords = "Kilovoltage, kVp, Mammography, Quality control",
author = "Napolitano, {Mary E.} and Trueblood, {Jon H.} and Hertel, {Nolan E.} and George David",
year = "2002",
month = "1",
day = "1",
doi = "10.1118/1.1501472",
language = "English (US)",
volume = "29",
pages = "2169--2176",
journal = "Medical Physics",
issn = "0094-2405",
publisher = "AAPM - American Association of Physicists in Medicine",
number = "9",

}

TY - JOUR

T1 - Mammographic x-ray unit kilovoltage test tool based on k-edge absorption effect

AU - Napolitano, Mary E.

AU - Trueblood, Jon H.

AU - Hertel, Nolan E.

AU - David, George

PY - 2002/1/1

Y1 - 2002/1/1

N2 - A simple tool to determine the peak kilovoltage (kVp) of a mammographic x-ray unit has been designed. Tool design is based on comparing the effect of k-edge discontinuity of the attenuation coefficient for a series of element filters. Compatibility with the mammography accreditation phantom (MAP) to obtain a single quality control film is a second design objective. When the attenuation of a series of sequential elements is studied simultaneously, differences in the absorption characteristics due to the k-edge discontinuities are more evident. Specifically, when the incident photon energy is higher than the k-edge energy of a number of the elements and lower than the remainder, an inflection may be seen in the resulting attenuation data. The maximum energy of the incident photon spectra may be determined based on this inflection point for a series of element filters. Monte Carlo photon transport analysis was used to estimate the photon transmission probabilities for each of the sequential k-edge filter elements. The photon transmission corresponds directly to optical density recorded on mammographic x-ray film. To observe the inflection, the element filters chosen must have k-edge energies that span a range greater than the expected range of the end point energies to be determined. For the design, incident x-ray spectra ranging from 25 to 40 kVp were assumed to be from a molybdenum target. Over this range, the k-edge energy changes by approximately 1.5 keV between sequential elements. For this design 21 elements spanning an energy range from 20 to 50 keV were chosen. Optimum filter element thicknesses were calculated to maximize attenuation differences at the k-edge while maintaining optical densities between 0.10 and 3.00. Calculated relative transmission data show that the kVp could be determined to within ± 1 kV. To obtain experimental data, a phantom was constructed containing 21 different elements placed in an acrylic holder. MAP images were used to determine appropriate exposure techniques for a series of end point energies from 25 to 35 kVp. The average difference between the kVp determination and the calibrated dial setting was 0.8 and 1.0 kV for a Senographe 600 T and a Senographe DMR, respectively. Since the k-edge absorption energies of the filter materials are well known, independent calibration or a series of calibration curves is not required.

AB - A simple tool to determine the peak kilovoltage (kVp) of a mammographic x-ray unit has been designed. Tool design is based on comparing the effect of k-edge discontinuity of the attenuation coefficient for a series of element filters. Compatibility with the mammography accreditation phantom (MAP) to obtain a single quality control film is a second design objective. When the attenuation of a series of sequential elements is studied simultaneously, differences in the absorption characteristics due to the k-edge discontinuities are more evident. Specifically, when the incident photon energy is higher than the k-edge energy of a number of the elements and lower than the remainder, an inflection may be seen in the resulting attenuation data. The maximum energy of the incident photon spectra may be determined based on this inflection point for a series of element filters. Monte Carlo photon transport analysis was used to estimate the photon transmission probabilities for each of the sequential k-edge filter elements. The photon transmission corresponds directly to optical density recorded on mammographic x-ray film. To observe the inflection, the element filters chosen must have k-edge energies that span a range greater than the expected range of the end point energies to be determined. For the design, incident x-ray spectra ranging from 25 to 40 kVp were assumed to be from a molybdenum target. Over this range, the k-edge energy changes by approximately 1.5 keV between sequential elements. For this design 21 elements spanning an energy range from 20 to 50 keV were chosen. Optimum filter element thicknesses were calculated to maximize attenuation differences at the k-edge while maintaining optical densities between 0.10 and 3.00. Calculated relative transmission data show that the kVp could be determined to within ± 1 kV. To obtain experimental data, a phantom was constructed containing 21 different elements placed in an acrylic holder. MAP images were used to determine appropriate exposure techniques for a series of end point energies from 25 to 35 kVp. The average difference between the kVp determination and the calibrated dial setting was 0.8 and 1.0 kV for a Senographe 600 T and a Senographe DMR, respectively. Since the k-edge absorption energies of the filter materials are well known, independent calibration or a series of calibration curves is not required.

KW - Kilovoltage

KW - kVp

KW - Mammography

KW - Quality control

UR - http://www.scopus.com/inward/record.url?scp=0036735657&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0036735657&partnerID=8YFLogxK

U2 - 10.1118/1.1501472

DO - 10.1118/1.1501472

M3 - Article

VL - 29

SP - 2169

EP - 2176

JO - Medical Physics

JF - Medical Physics

SN - 0094-2405

IS - 9

ER -