Python SimpleITK 统计医学图像mask的体积

import SimpleITK as sitk
import os
import pandas as pd
import csv
import numpy as np

def volume_static(image):
    stats = sitk.StatisticsImageFilter()
    img = sitk.ReadImage(image)
    stats.Execute(img)
    spacing = img.GetSpacing()
    voxel = np.prod(spacing)  
    img_np = sitk.GetArrayFromImage(img)
    left_np = img_np.copy()
    right_np = img_np.copy()
    left_np[left_np == 2] = 0
    right_np[right_np == 1] = 0
    right_np[right_np == 2] = 1
    vol_left = voxel*np.sum(left_np)
    vol_right = voxel*np.sum(right_np)
    return vol_left, vol_right

if __name__ == '__main__':
	# image path
    root_path = r'/home/xx'
    case_list = os.listdir(root_path)
    case_list.sort()
    header = ['case_name', 'left', 'right']
    with open ('/home/xx/stage2_3.csv','w',encoding='utf-8') as fp:
        for case in case_list:
            case_path = os.path.join(root_path, case)
            volume_left, volume_right = volume_static(case_path)
            writer =csv.writer(fp)
            writer.writerows([[case, volume_left, volume_right]])