ICRP 110 Phantoms
ICRP publication 110 introduced computational models representing adult male and female reference models in the form of voxel phantoms. The models consist of ASCII voxel data (
M) plus material (
AX_media.dat) and organ segmentation (
AX_media.dat) tables. Scan2MCNP can read both the data and the tables. The female model is shown at the right.
Items for reading the ICRP 110 files are contained in the Read submneu of the File menu. The material (media) file must be read first. Any existing materials, such as those loaded by reading the material libary, are deleted. The segmentation file (organs) should be read next. These 2 files are automatically read when loading AX.dat if the files are present in the same directory with the expected names mentioned above. Before loading the phantom data, ICRP 110 and Segmented must be checked and the voxel extents (Rows, Columns, and Slices) entered on the IMG Parameters dialog. One may also wish to enter the voxel size (Dimensions). Unlike image data in binary format, the program cannot determine the number of slices from the size of the file.
Two voxel numbers are not defined in the organs file. Voxel number 0 is the space surrounding the model. The program replaces 0 with (maximum organ number + 2) and assigns air as the material (assuming air is last or penultimate material used in the organs file). The other unassigned voxel number (141 in the models we have seen) is present in the first and last slices. The user has the choice of having this number represent skin or air (or other surrounding medium). In either case, the user must add a line to the organs file to define that voxel number.
As with other segmented data, the MCNP conversion must use a single pixel per voxel cell. Material mixing is not supported.
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