================================ xtubes ==================================== xtubes is an widget based graphical interface to calculate the spectum of an X-ray tube with Mo, Rh or W target in the energy range 18-40 keV. It uses the method descibed in the manuscript: "Molybdenum, rhodium, and tungsten anode spectral models using interpolating polynomials with application to mammography" J.M. Boone T.H. Fewell and R. J. Jennings Medical Physics 24(12) pp. 1863-1874, 1997. The program interfaced by XTubeW has been downloaded from: ftp://ftp.aip.org/epaps/medical-phys/E-MPHYA-24-1863 DESCRIPTION OF THE CONTROLS IN THE MAIN WINDOW: File: xtubes input parameters: This option allows to save the current parameters to a file for later loading. It also allows to save the current parameters as defaults for being used when the application is initialized. In the last case, the file is named "application".xop (where "application " is the name of the current XOP application) and is written in the directory pointed by the XOP_DEFAULTS_DIR environment variable (which must be set). The parameter file is ASCII and can be read and edited with care. Write Files for XOP/Optics: Saves the current undulator spectrum in the SRCOMPE (flux) and SRCOMPW (Power) files to be used for the other XOP application from Optics menu. Quit: to exit from the program Set_Parameters: Set Parameters: to define the parameters for the calculation. The same result is obtained pressing the "Set Parameters" button in the main xtubes window. Please refer to the information under the HELP button for a complete description of the parameters. After pressing the ACCEPT button, xtubes starts running. Set Defaults: Sets the default parameters. Show: Display results Plot Results: Plots the xtubes results (see note on units). Help: Shows the xtubes help (this text). NOTE ON RESULT UNITS: The units of the fluence in the results are not very clear in the Boone's paper. This has creates some problems for users, and originated a discussion between Sutter (sutter@ntmail.desy.de) and Boone. You can find below a short version of the discussion: In the paper for the W (only) [XOP program xtube_w] Boone's paper clearly states that the flux per sec per 1keV bandwidth and per mm2 collected at 1m from the target. The result looks very reasonable, and I (srio@esrf.fr) have checked one result against the example in the doc of "Catalogue of diagnostic x-ray spectra and other data", Cranley et al., Report 78, The Institute of Physics and Engineering in Medicine, with quite reasonable agreement. However, in the paper on Mo, W and Rh [code Xtubes] the units are not clearly stated. Moreover, both programs produced different results for W @ > 41 keV (one case that can be calculated with both codes). I (sutter@ntmail.desy.de) have had several interesting exchanges with Dr. Boone. The units: The paper on Mo, W, and Rh states that the spectra collected on these tubes were binned into 500 eV intervals. (See Fig. 2 for an example of these spectra for the Mo anode.) In addition, the caption of Fig. 2 states that all the spectra were normalized to a constant value of mA x sec, but does not reveal what this value was. When I asked Boone about this, he said that his reason for not revealing it was the following: "You are correct, I intentionally did not "reveal" the absolute output efficiency of the x-ray sources because x-ray tubes are so variable - the calibration of the mA (and the time) is often imperfect (and hence the mR/mAs term would be in error) and the amount of inherent x-ray tube filtration (we deal with tubes in the clinical environment, which have collimators and other structures over the x-ray tube port which make it difficult and impractical to visually check exactly what filters are in the beam. Thus, the total inherent (and added) filtration is often not known.)" When I pressed him for at least an approximate value for the normalizing constant, he stated that it was 1 mA x sec. However, the above warning about the variability of X-ray tubes should be kept in mind. In short, the units for the fluence, strictly speaking, should be: photons/mm2/500 eV/(mA.s). One final note: Boone stated in another message to me that the fluence from a point source drops off with the inverse square law. This indicates that the area unit (mm2) in the fluence refers to the number of photons per unit surface area on a sphere of given radius centered on the anode, rather than to the number of photons produced per unit illuminated area on the anode. Another quantity that isn't given with certainty in Boone's first paper is the distance between the Mo, Rh, and W tubes and the detector. When I asked Boone for this quantity, he said it was "probably 50 cm," this being a common distance for mammography measurements. The measurements for the W tube in Boone's second paper, corresponding to the XOP program "xtubes_w", however, are clearly stated to have been made at 1 m from the tube. Perhaps this explains the discrepancy between the results from the two calculation routines xtube_w and Xtubes . Does this make sense? (The fact that 500-eV bins are used in the first paper, while the fluence in the second is given per 1 keV bandwidth, will also influence the results.) Added srio@esrf.fr: Following this arguments, in order to transform the units of xtubes (fluence @0.5m with 0.5keV bandwidth) into xtube_w units (fluence @1m with 1keV bandwidth) one should multiply by (0.5/1.0)^2 * 2 = 1/2 (in other words, at 1m we have 1/4 times the flux of at 0.5m multiplied again by 2 because we use the double of bandwidth). However, a strage factor of about 1000 is found: W @ 41 kV Photon_Energy[keV] Fluence[xtube_w] Fluence[xtubes] 25 1.24e4 1.23e7 35 7.02e3 4.39e6 I have no explanation for this discrepancy. COPYRIGHT: XTUBES belongs to XOP package and it is distributed within XOP. PLEASE REFER TO THE XOP COPYRIGHT NOTICE REFERENCE: Published calculations made with XOP should refer: M. Sanchez del Rio and R. J. Dejus "Status of XOP: an x-ray optics software toolkit" SPIE Proceedings Vol. 5536 (2004) pp.171-174 http://dx.doi.org/10.1117/12.560903 In addition, published calculations using the xtubes aplication should also cite: J.M. Boone T.H. Fewell and R. J. Jennings "Molybdenum, rhodium, and tungsten anode spectral models using interpolating polynomials with application to mammography" Medical Physics 24(12) pp. 1863-1874, 1997. LAST MODIFICATION: srio@esrf.eu 2008-01-28