block = [32, 32, 16]
img = imageio.volread('path\to\tiff\file')
x, y, z = 191, 303, 17
img_block = img_block[x - int(block[0] / 2):x + int(block[0] / 2),
                              y - int(block[1] / 2):y + int(block[1] / 2),
                              z - int(block[2] / 2):z + int(block[2] / 2)]