Specific Muscle Segmentation

Hi, I’m a graduate student and I’m splitting my thoracic muscles right now.
For now, we are using thresholds provided by Slicer to divide the muscles, and then we are removing the skin muscles and internal organs.
For detectors, we are removing them using Scissor.
However, one patient has about 520 sheets of dcm, and it takes three to four days to process them all.
I also tried Growseeds or Between Slide, but it was difficult to use as it was segmented to the areas I didn’t want.
I hope you can let me know so that I can process it faster.
Thank you in advance.