The role of hybrid cameras in oncology

The rapid advances in imaging technologies are a challenge for nuclear medicine physicians, radiologists, and clinicians who must integrate these technologies for optimal patient care and outcome at minimal cost. Multiple indications for functional imaging using F-18-fluorodeoxyglucose (FDG) are now well accepted in the field of oncology, including differentiation of benign from malignant lesions, staging malignant lesions, detection of malignant recurrence, and monitoring therapy. The use of FDG imaging was first shown using dedicated positron emission tomography (PET) with multiple full rings of bismuth germanate detectors. Most manufacturers now have available hybrid gamma cameras capable of imaging conventional single-photon emitters, as well as positron emitters such as FDG. This new technology was developed to make FDG imaging more widely accessible, first using single photon emission computed tomography (SPECT) with high-energy collimators, and then using dualhead coincidence (DHC) detection with multihead gamma cameras that improved spatial resolution. Most hybrid gamma cameras are now equipped with thicker NaI(TI) crystals to improve sensitivity. Technical developments are still evolving with correction for attenuation and new iterative reconstruction algorithms to improve the quality of the images. Users need to be familiar with the rapid developments of the technology as well as its limitations. Currently, one model of hybrid gamma camera is equipped with an integrated x-ray transmission system for attenuation correction, anatomic mapping, and image fusion. This powerful tool has promising clinical applications including intensity-modulated radiation therapy.