Introduction to novel developments in radio-imaging and radiotherapy.

Radiation therapy has long been known to be a very effective form of therapy in relieving symptoms and prolonging the life of patients with brain metastases. Novel developments in this field have allowed oncologists to improve on older forms of radiation therapy; these recent advances in radiotherapeutic techniques (stereotactic radiosurgery and hippocampal-avoidant whole brain radiation therapy) allow sparing of the healthy brain from receiving unnecessary radiation while delivering effective treatment to the metastases, thus improving the quality of life for surviving patients. Furthermore, multiple clinical trials have documented the increased loco-regional control in the brain when radiosurgery is interdigitated with immune check point inhibitors for treatment of melanoma brain metastases. Mild hyperthermia has been used for decades as an adjuvant to radiotherapy in the treatment of radiation resistant cancers; lately, however, thermal therapies, such as hyperthermia, cryoablation, radiofrequency ablation and high intensity focused ultrasound are being investigated to provide a new ablative approach to cancer while thermoacoustic imaging and thermometry have recently been proposed as new techniques for monitoring tissue temperature in the breast during ablation treatment. In addition, other hybrid techniques have emerged that combine ultrasounds with other forms of energy such as light to provide a more accurate diagnosis and enhance the efficacy of therapy for early and late stage cancers.