fractalFeatures: Fractal features
In kbolab/moddicom: Package for handling DICOM RT files

This function extracts fractal features using the box counting technique.

1 2	fractalFeatures(imgObj, fstPerc = 0, lstPerc = 100, ThDown = 0, ThUp = 100, onepxwide = T)

`imgObj`	The imgObj get as input the GTV object extracted using getROIVoxels method.
`fstPerc`	A `numeric` value for normalized the image. It is the first percentile.
`lstPerc`	A `numeric` value for normalized the image. It is the last percentile.
`ThDown`	A `numeric` value for masked image filter. It is the minimum value of the threshold
`ThUp`	A `numeric` value for masked image filter. It is the maximum value of the threshold

## Not run: 
# Create an instance of geoLet object and load a case
obj <- geoLet()
obj$openDICOMFolder(pathToOpen = './patient1')

# get the ROI
GTV <- obj$getROIVoxels(Structure = 'GTV')

# extract the fractal feature
 Fractal <- fractalFeatures(imgObj = GTV, fstPerc = 1, lstPerc = 99, ThDown = 0, ThUp = 100)


## End(Not run)