Imaging in cancer

Medical imaging techniques are an important element in early detection for many cancers. They are also important for determining the stage and extension of the lesion, assessing tumour response during and after treatment, and locating cancer to aid surgery and other treatments. Imaging methods range from anatomical-based methods (ultrasound, conventional plain X-rays with mammography, computed tomography) to the more functional-based methods (magnetic resonance imaging with a spectroscopy option, single-photon emission computed tomography and positron emission tomography). The principles of image acquisition methods with examples of clinical indications are described in the article. Advances in medical imaging have also been widely applied in the field of radiation oncology. Technical development has lead to more accurate treatment plan calculations and more precise administration of the radiation. The range of imaging applications in radiation oncology is very wide and often called ‘therapeutic imaging’. Medical imaging is employed at almost every step of the radiation treatment process from diagnosis, treatment planning, dose calculations, and simulation of real treatment, to irradiation on the linear accelerator.