ABSTRACT
This chapter provides an overview of the use of x-ray and computed tomography (CT)-based imaging for brachytherapy. Treatment planning in brachytherapy requires accurate imaging of both the implanted materials and the surrounding anatomy. Ultrasound (US) and magnetic resonance imaging (MRI), which can provide excellent soft-tissue contrast for visualizing anatomy, can be limited in depicting radioactive seeds or interstitial needles. X-ray and CT, however, can provide excellent visualization of most implanted materials and electron density information. Transrectal ultrasound (TRUS) guidance is the main imaging modality for modern prostate brachytherapy. Since the 1990s, intraoperative treatment planning has emerged as an increasingly viable alternative to preplanning. During intraoperative planning, prostate imaging, treatment planning, and radioactive seed implantation are performed within a single session. The basic premise of x-ray fluoroscopy for intraoperative dose assessment is that the three-dimensional (3D) source distribution of radioactive seeds can be reliably reconstructed from multiple fluoroscopic images obtained at different angles.
