Positron Emission Tomography-Computed Tomography Protocols for Radiation Therapy Planning and Therapy Response Assessment

Role of positron emission tomography-computed tomography in pulmonary neoplasms

Positron emission tomography (PET)-computed tomography (CT) has become a routine imaging modality in body oncology and is particularly well suited for the management of patients with lung cancer. Current clinical applications of PET-CT in patients with lung cancer include evaluation of indeterminate pulmonary nodules, initial staging of lung cancer, restaging of lung cancer following treatment, and radiation therapy planning. Contemporary PET-CT scanners allow comprehensive diagnostic PET and CT imaging in a single imaging session. Interpretation and reporting of PET-CT examinations of patients with lung cancer require a thorough and integrated approach taking advantage of the anatomic and metabolic information.

Motion management in positron emission tomography/computed tomography for radiation treatment planning

Hybrid positron emission tomography (PET)/computed tomography (CT) scanners combine, in a unique gantry, 2 of the most important diagnostic imaging systems, a CT and a PET tomograph, enabling anatomical (CT) and functional (PET) studies to be performed in a single study session. Furthermore, as the 2 scanners use the same spatial coordinate system, the reconstructed CT and PET images are spatially co-registered, allowing an accurate localization of the functional signal over the corresponding anatomical structure. This peculiarity of the hybrid PET/CT system results in improved tumor characterization for oncological applications, and more recently, it was found to be also useful for target volume definition (TVD) and treatment planning in radiotherapy (RT) applications. In fact, the use of combined PET/CT information has been shown to improve the RT treatment plan when compared with that obtained by a CT alone. A limiting factor to the accuracy of TVD by PET/CT is organ and tumor motion, which is mainly due to patient respiration. In fact, respiratory motion has a degrading effect on PET/CT image quality, and this is also critical for TVD, as it can lead to possible tumor missing or undertreatment. Thus, the management of respiratory motion is becoming an increasingly essential component in RT treatment planning; indeed, it has been recognized that the use of personalized motion information can improve TVD and, consequently, permit increased tumor dosage while sparing surrounding healthy tissues and organs at risk. This review describes the methods used for motion management in PET/CT for radiation treatment planning. The article covers the following: (1) problems caused by organ and lesion motion owing to respiration, and the artifacts generated on CT, PET, and PET/CT images; (2) data acquisition and processing techniques used to manage respiratory motion in PET/CT studies; and (3) the use of personalized motion information for TVD and radiation treatment planning.

Patient and image data management in positron emission tomography-computed tomography for radiation therapy and therapy response assessment

This article provides an overview of the primary considerations of positron emission tomography-computed tomographic (PET-CT) workflows specifically related to patient and image data management in radiation therapy (RT) planning and therapy response assessment. PET-CT has become increasingly integral to the RT planning and therapy response assessment. There are numerous workflow challenges related to integrating PET-CT in the framework of RT planning and therapy assessment. For PET-CT scan used for RT planning, accurate patient positioning and scan registration with the simulation is critical. For therapy assessment PET-CT scans, consistency in patient preparation, scanning and image reconstruction parameters, and image analysis are critical.