Erica Bass/ Rogel Cancer Center/ Michigan MedicineUltrasound has long been used for helping doctors see inside the body, but focused high frequency sound waves are offering new ways of targeting cancer.If Zhen Xu hadn't annoyed her lab mates, she might never have discovered a groundbreaking treatment for liver cancer.As a PhD student in biomedical engineering at the University of Michigan in the US during the early 2000s, Xu was trying to find a way for doctors to destroy and remove diseased tis...