IEC 60336:2020 pdf free.Medical electrical equipment – X-ray tube assemblies for medical diagnosis -Focal spot dimensions and related characteristics.
lf the LOADING FACTORs according to Table 2 do not fall within the RADIOGRAPHICRATINGs for theX-RAY TUBE concerned or if they otherwise do not cover the typical special applications ofspecified NORMAL USE of the X-RAY TUBE,LOADING FACTORs shall be chosen to correspond tothose specific conditions. In this case, the LOADING FACTORs under which the FocAL SPOT sLITRADIOGRAMs or FOCAL SPOT PINHOLE RADIOGRAMs were obtained shall be stated in the statementof compliance together with the characteristics.
ln particular cases, it may be appropriate to state the characteristics of a FoCAL SPoT underadditional LOADING conditions.
6.2.4Special arrangements
lf, for the purpose of production of suitable FocAL SPOT SLIT RADIOGRAMS, arrangements weremade for the adjustment and alignment of either the sLIT cAMERA or X-RAY TUBE ASSEMBLY, or ifspecial electrical or LOADING conditions prevailed,details shall be stated together with thecharacteristics in the statement of compliance.
6.3 Production of FOCAL SPOT SLIT RADIOGRAMS,FOCAL SPOT PINHOLE RADIOGRAMs and FOCAL SPOT LINE SPREAD FUNCTIONS
6.3.1 DIGITAL FOCAL SPOT DETECTOR requirements for FOCAL SPOT SLIT RADIOGRAMS
The spatial range of the FocAL SPOT SLITRADIOGRAM shall be such that further extension of thespatial range does not significantly change the result for the 15 % width.
NOTE In general, the spatial range of three times the 15 % width of the LINE SPREAD FUNCTION is sufficient.
Discretization errors are inherent to digital detectors and the subsequent signal processing.These errors will lead to LINE SPREAD FUNCTION widths which are larger than in the ideal case.The following choice of parameters is recommended in order to limit the error induced bydiscretization to about 1 %.
a) The number of pixels over the 15 % width of the LINE SPREAD FUNCTION is at least 30,and linear interpolation is applied. lf linear interpolation is not applied, the number of pixels should be at least 60.
b) The number of levels between the background level and the maximum signal of the LINESPREAD FUNCTION is 200 or more.
c) The signal to noise ratio is 200 or better.
6.3.2 DIGITAL FOCAL SPOT DETECTOR requirements for FocAL SPOT PINHOLE RADIOGRAMSThe spatial range of the FOCALSPOT PINHOLE RADIOGRAM shall be such that that the outermostportions of the RADlOGRAM are well included, so that the true background-level of the RADIOGRAMcan be perceived correctly.IEC 60336 pdf download.