Ultrasound: A method used to obtain images for medical diagnostic purposes by measuring the transmission of frequency or ultrasonic waves. 

Ultrasound-guided biopsy:  Fine needle aspiration or core biopsy with guidance from ultrasound.

V

Vaccine:  A substance containing antigenic components from an infectious organism.  By stimulating an immune response, it protects against subsequent infection by that organism.

Visualization:  Use of imagery and visual pictures to help reduce stress and to promote healing.

W

White blood cells: Part of the immune system manufactured by bone marrow, a component of blood.

X

X Ray:  A high-energy electromagnetic wave able to penetrate most solid matter and to act on photographic film, used for detecting or treating cancer.