Journal of the ICRU Vol 4 No 2 (2004) Report 72 Oxford University Press
SYMBOLS AND ACRONYMS A A0 Ai a
Activity of a source Apparent activity of a source Mass number of element i Area of a collecting electrode of an extrapolation chamber; radius of a disc-shaped source av Activity divided by volume as Activity divided by surface area (surface activity) am Activity divided by mass (mass activity) B Normalizing constant in point-source dose functions c Dimensionless parameter in point-source dose equations; factor for unit conversion in the equation for air-kerma-rate constant C Capacitance CSDA Continuous-slowing-down approximation d Diameter of a source D_ Absorbed-dose rate D_ m Absorbed-dose rate to medium m D_ P Absorbed-dose rate at point P D_ ð xÞ Absorbed-dose rate at a distance x from a source D_ avg Average absorbed-dose rate D_ max Maximum absorbed-dose rate D_ min Minimum absorbed-dose rate E, hEbi Mean kinetic energy of a beta-particle spectrum e Electron charge Ei Photon energy Emax Maximum kinetic energy of a beta-particle spectrum f Dimensionless parameter in point-source dose functions F(r,u) Anisotropy function gr0 (r) Radial dose function G(r,u) Geometry factor h Thickness of a source I, Ic Corrected current measured by an extrapolation chamber Inet Net ionization current J(x) Beta-ray point-source dose function (absorbed-dose rate per unit activity at distance x from a point source) K_ Air-kerma rate kback Correction for difference in electron backscatter kdi Correction for the effect of source radiation field divergence krecom Correction for recombination losses in an ionization measurement kTp Correction to reference conditions of temperature and pressure kfilter Correction for attenuation in filter kab Correction for source-to-aperture air attenuation kac Correction for aperture-to-WAFAC air attenuation kap Inverse-square correction for aperture khum Humidity correction kscat Correction for in-chamber photon scatter ª International Commission on Radiation Units and Measurements 2004
DOI: 10.1093/jicru/ndh022
DOSIMETRY OF BETA RAYS AND LOW-ENERGY PHOTONS FOR THERAPEUTIC APPLICATIONS
kstem kpene kelec kbuil L ‘ N p p0 r
Source-holder stem-scatter correction Aperture-penetration correction In-chamber electron-loss correction External-photon-scatter (build-up) correction Active length of a seed or line source Chamber depth of an extrapolation chamber (air-gap width) Number of spontaneous nuclear transformations Pressure Reference pressure Radial distance from the center of a source; radial distance from the central axis r0 Reference distance R Correction term in point-source dose function (Cross function) R50 The radius of the 50% isodose contour of a dose distribution Rmax CSDA range of the most energetic beta particle K_ d Reference air-kerma rate sw,air Ratio of spectrum-averaged stopping power of water to that of air S/r Total mass stopping power (S/r)col Collision mass stopping power t Time; integration time T Temperature T0 Reference temperature U Source non-uniformity V Voltage induced in a capacitor during an ionization measurement; volume of the source wi Atomic weight of element i W Mean energy to produce an ion pair in air WAFAC Wide-angle free-air chamber x Distance from a point source X Electric field z Depth in a medium z0 Reference location in a plane perpendicular to the source plane Zeff Effective atomic number Zi Atomic number of element i a Parameter in point-source dose functions b Angle subtended by the effective active-source length L Gd Air-kerma rate constant d Cut-off energy of a spectrum FE dE Fluence of electrons between energy E and E þ dE f Azimuthal angle fan Anisotropy factor an Anisotropy constant f h Scaling factor for beta particles L r0 Dose-rate constant Lb Absorbed-dose rate conversion factor (m/r)m Mass attenuation coefficient of medium m (men/r)m Mass-energy absorption coefficient of medium m n Apparent absorption coefficient of a beta-particle source r Density of a material r0 Density of air at reference temperature and pressure r(r0 ) Activity per unit volume at a point r0 within a source u Angle with respect to the axis of a seed or line source u0 Reference angle with respect to the axis of a seed or line source vi Number of photons with energies Ei greater than d s Standard deviation 12
SYMBOLS AND ACRONYMS A A0 Ai a
Activity of a source Apparent activity of a source Mass number of element i Area of a collecting electrode of an extrapolation chamber; radius of a disc-shaped source av Activity divided by volume as Activity divided by surface area (surface activity) am Activity divided by mass (mass activity) B Normalizing constant in point-source dose functions c Dimensionless parameter in point-source dose equations; factor for unit conversion in the equation for air-kerma-rate constant C Capacitance CSDA Continuous-slowing-down approximation d Diameter of a source D_ Absorbed-dose rate D_ m Absorbed-dose rate to medium m D_ P Absorbed-dose rate at point P D_ ð xÞ Absorbed-dose rate at a distance x from a source D_ avg Average absorbed-dose rate D_ max Maximum absorbed-dose rate D_ min Minimum absorbed-dose rate E, hEbi Mean kinetic energy of a beta-particle spectrum e Electron charge Ei Photon energy Emax Maximum kinetic energy of a beta-particle spectrum f Dimensionless parameter in point-source dose functions F(r,u) Anisotropy function gr0 (r) Radial dose function G(r,u) Geometry factor h Thickness of a source I, Ic Corrected current measured by an extrapolation chamber Inet Net ionization current J(x) Beta-ray point-source dose function (absorbed-dose rate per unit activity at distance x from a point source) K_ Air-kerma rate kback Correction for difference in electron backscatter kdi Correction for the effect of source radiation field divergence krecom Correction for recombination losses in an ionization measurement kTp Correction to reference conditions of temperature and pressure kfilter Correction for attenuation in filter kab Correction for source-to-aperture air attenuation kac Correction for aperture-to-WAFAC air attenuation kap Inverse-square correction for aperture khum Humidity correction kscat Correction for in-chamber photon scatter ª International Commission on Radiation Units and Measurements 2004
DOI: 10.1093/jicru/ndh022
DOSIMETRY OF BETA RAYS AND LOW-ENERGY PHOTONS FOR THERAPEUTIC APPLICATIONS
kstem kpene kelec kbuil L ‘ N p p0 r
Source-holder stem-scatter correction Aperture-penetration correction In-chamber electron-loss correction External-photon-scatter (build-up) correction Active length of a seed or line source Chamber depth of an extrapolation chamber (air-gap width) Number of spontaneous nuclear transformations Pressure Reference pressure Radial distance from the center of a source; radial distance from the central axis r0 Reference distance R Correction term in point-source dose function (Cross function) R50 The radius of the 50% isodose contour of a dose distribution Rmax CSDA range of the most energetic beta particle K_ d Reference air-kerma rate sw,air Ratio of spectrum-averaged stopping power of water to that of air S/r Total mass stopping power (S/r)col Collision mass stopping power t Time; integration time T Temperature T0 Reference temperature U Source non-uniformity V Voltage induced in a capacitor during an ionization measurement; volume of the source wi Atomic weight of element i W Mean energy to produce an ion pair in air WAFAC Wide-angle free-air chamber x Distance from a point source X Electric field z Depth in a medium z0 Reference location in a plane perpendicular to the source plane Zeff Effective atomic number Zi Atomic number of element i a Parameter in point-source dose functions b Angle subtended by the effective active-source length L Gd Air-kerma rate constant d Cut-off energy of a spectrum FE dE Fluence of electrons between energy E and E þ dE f Azimuthal angle fan Anisotropy factor an Anisotropy constant f h Scaling factor for beta particles L r0 Dose-rate constant Lb Absorbed-dose rate conversion factor (m/r)m Mass attenuation coefficient of medium m (men/r)m Mass-energy absorption coefficient of medium m n Apparent absorption coefficient of a beta-particle source r Density of a material r0 Density of air at reference temperature and pressure r(r0 ) Activity per unit volume at a point r0 within a source u Angle with respect to the axis of a seed or line source u0 Reference angle with respect to the axis of a seed or line source vi Number of photons with energies Ei greater than d s Standard deviation 12
