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Radiology, 1957
The purpose of this communication is to present, in convenient form, values for the half-value depths and fall-off ratios corresponding to the entire range of radiation qualities, portal areas, and target-skin distances likely to be encountered in clinical roentgen therapy. Compilation of these data is believed to be useful for several reasons.
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The purpose of this communication is to present, in convenient form, values for the half-value depths and fall-off ratios corresponding to the entire range of radiation qualities, portal areas, and target-skin distances likely to be encountered in clinical roentgen therapy. Compilation of these data is believed to be useful for several reasons.
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On the choice of material for half‐value‐layer measurements for megavoltage x rays
Medical Physics, 1977The relative sensitivity of various materials for the measurement of half‐value‐layer thickness has been calculated for bremsstrahlung x‐ray spectra in the energy range 5–40 MeV. It is concluded that low‐atomic‐number materials such as water are more sensitive to changes in spectral quality of megavoltage x rays than high‐atomic‐number materials such ...
R, Nath, R J, Schulz
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A Nomogram for the Determination of Half-value Layers
The British Journal of Radiology, 1936Although a statement of the half-value layer alone does not specify the X-ray quality of the radiation in the sense of the accepted definition, it is often sufficient to characterise the radiation. An analysis of the results of several workers shows that a statement of exciting voltage, filtration and type of generator (constant—or pulsating—potential)
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EXPERIMENTAL AND MATHEMATICAL MODELING OF HALF-VALUE LAYER MEASUREMENTS FOR X-RAY EQUIPMENT
Biomedical Engineering: Applications, Basis and Communications, 2016A linear mathematical modeling of half-value layer measurements for X-ray equipment is discussed. The consistency check shows that a linear model is consistent with the value of an exponential model, provided that the thickness of the aluminum absorber used in the calculations is close to 2.5[Formula: see text]mm.
Modesto Sosa +5 more
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A parametric method for determining mammographic X‐ray tube output and half value layer
The British Journal of Radiology, 2001In the National Health Service Breast Screening Programme, regular assessment of the mean glandular doses received by a group of women is recognized as an important part of a quality assurance programme. The use of different tube voltages, to improve the beam penetration for thick or dense breasts, and of X-ray units with programmable exposure modes ...
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A simple method of obtaining off‐axis half‐value layers for megavoltage photon beams
Medical Physics, 1995We describe a simplified technique for the acquisition of off‐axis beam‐quality data (i.e., half‐value layers in water) for medical linear accelerators. A measurement protocol is presented in which an ordinary beam‐scanning water phantom is used to accurately position an ionization chamber at appropriate measuring positions.
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Half-value layer measurement using a radiochromic film for QA and QC
2008Purpose Methods and Materials Results ...
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Direct half value layer measurements in mammography - is near enough good enough?
2014Aim: The accuracy of mean glandular dose (MGD) measurement in mammography depends upon several factors, one of which is half value layer (HVL). This can be calculated from measurements of air kerma with and without aluminium filters in the beam, or...
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Problem of Determination of the First Half-Value Layer of X-Ray Radiation
Biomedical Engineering, 2009The methods for determination of the first half value layer of X-ray radiation are analyzed. The organized comparison revealed significant scatter from different sources of the first half value layer for identical conditions. The analytical expression was derived for calculation of the first half value layer based on the measured value and total ...
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