Nuclear medicine plays a key role in evaluating thoracic conditions across benign and malignant entities. The inherent quantitative capabilities of nuclear medicine imaging have been adapted for better characterization of pulmonary disease phenotypes and treatment response assessment. In this chapter, we first provide an overview of the underlying medical physics for quantitative nuclear medicine imaging. Next, we review benign and oncologic conditions commonly assessed with quantitative nuclear medicine and molecular imaging, including applying molecularly targeted radionuclide therapies (a.k.a. theranostics). Finally, novel molecular imaging and therapeutic assays with promising translational potential for thoracic imaging are discussed.