This chapter reviews the transformative period in radiation oncology from 2005 to 2015, highlighting significant advancements in treatment technologies, modalities, and the progress in standardization. Key developments included the widespread adoption and technical maturation of image-guided radiation therapy (IGRT) and stereotactic body radiation therapy (SBRT), which expanded treatment options for various extracranial sites such as lung, spine, liver, and prostate cancers. The increasing sophistication of these techniques, alongside the introduction of advanced delivery platforms like volumetric-modulated arc therapy (VMAT), underscored the critical need for standardization. This era saw the foundational development of clinical practice guidelines (CPGs) and consensus statements by professional organizations, aimed at improving consistency in target and normal tissue delineation through anatomical atlases, enhancing patient safety via principles like ALARA, and reducing medical-legal risks. The chapter details the impact of these guidelines on specific cancer sites (head and neck, gynecologic, gastrointestinal, lung) and the technical specifications established for advanced treatments. Furthermore, it examines the evolution of normal tissue complication models (e.g., QUANTEC, AAPM TG101) and the development of new commissioning and quality assurance (QA) protocols essential for the safe and effective implementation of these complex technologies. Ultimately, the efforts during this decade laid the essential groundwork for contemporary evidence-based radiation oncology, enhancing targeting accuracy, expanding treatment paradigms, and ensuring the safety and quality of patient care amidst rapid technological evolution.