This talk emphasizes that patient data, including images, are not operable (clinically), but that digital twins are. Based on the former, the latter can be created. Subsequently, virtual clinical operations can be performed towards selection of optimal therapies. Digital twins are beginning to emerge in the field of medicine.. We elaborate on the importance of digital twins in a future where ‘one-size-fits-all’ therapeutic schemes are transcended. Important mathematical and computational developments will be made in the area of physiologically based pharmacokinetic modeling (PBPK), as key engines of digital twins. Multi-modal multi-scale images, combined with other data and aided by computational techniques, will be utilized towards routine digital twinning of patients, and will enable improved deliveries of therapies and overall healthcare.