.. _basedata_photons: ====================== Photon Base Data File ====================== This page describes the format and the variables as part of the particle base data files `protons_Generic.mat `_ and `carbon_Generic.mat `_. The base data is stored using MATLAB's structure format. The first sub level of the structure 'machine' contains two fields named 'meta' and 'data' which are explained separately next. machine.version --------------- Specifies the version of the machine file. If not present, version 1 is assumed. Currently version 1 and 2 are supported. Version 2 is the current standard used in matRad. It's main difference to version 1 is that kernel normalization does not imply a convolution grid of 0.5 mm. machine.meta ------------ Stores relevant isolated meta information describing the actual base data file that does not fit into the machine.data structure. machine.meta.name ^^^^^^^^^^^^^^^^^ Actual machine name as string to identify the base data set during runtime. machine.meta.radiationMode ^^^^^^^^^^^^^^^^^^^^^^^^^^ The radiationMode stores the radiation modality the base data is describing. Logically, `protons_Generic.mat `_ models protons in water and the corresponding field machine.meta.radiationMode is set to 'protons'. machine.meta.SAD ^^^^^^^^^^^^^^^^ This subfield holds the geometrical source to axis distance in millimeter. In case of the generic base data set, we use a value of 1000 [mm]. machine.meta.SCD ^^^^^^^^^^^^^^^^ This subfield holds the geometrical source to collimator distance in millimeter. In case of the generic base data set, we use a value of 500 [mm]. This value is mainly used to convert between penumbra and source width. machine.data ------------ This subfield contains the detailed dosimetric machine information. It is currently only storing decomposed pencil-beam kernels according to `Bortfeld et al. (1993) Medical Physics `_. machine.data.energy ^^^^^^^^^^^^^^^^^^^ Maximum photon energy in MeV. Corresponds to the acceleration potential in MV. machine.data.betas ^^^^^^^^^^^^^^^^^^ Beta factors for the individual kernels. Row array with length of number of kernels. machine.data.m ^^^^^^^^^^^^^^ Attenuation factor (obtained from kernel fitting). machine.data.primaryFluence ^^^^^^^^^^^^^^^^^^^^^^^^^^^ Radial fluence distribution of a photon beam. machine.data.kernelPos ^^^^^^^^^^^^^^^^^^^^^^ Lateral Kernel evaluation positions in [mm]. Alle kernels in machine.data.kernel are tabulated at these positions. machine.data.penumbraFWHMatIso ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Penumbra full width half maximum (FWHM) at isocenter in [mm]. This value is used to convert between penumbra and source width and in kernel convolution with the field function. machine.data.kernel ^^^^^^^^^^^^^^^^^^^ Structure Array with all kernels by SSD. Each kernel struct contains the field ``SSD`` to tell the corresponding SSD for which the kernel components were fitted. Further fields enumerate the kernels, i.e.: ``kernel1``, ``kernel2``, ``kernel3``, etc. Each kernel is tabulated at the positions given in ``machine.data.kernelPos`` and has been fitted to the measured data. Number of kernels must match the length of ``machine.data.betas``.