Dose Calculation

Model-based dose calculation algorithms (MBDCAs) for brachytherapy are methods that are driven by physics-based models of varying complexity and are capable of providing improved dosimetric accuracy over traditional methods. MBDCA and the imaging methods needed to support them are emerging topics in brachytherapy. This chapter will cover both “conventional brachytherapy” with sealed radioactive sources or miniature x-ray tubes of millimeter dimensions and emitting photons with energies from 20 keV to 1.25 MeV and targeted radionuclide therapy with sealed sources of very small dimensions as, such as, Y microsphere brachytherapy, emitting beta particles. Computed tomography (CT) images used to gather information on the individual patient’s tissues in terms of their atomic composition is lacking in accuracy, causing severe problems especially at low energies where it is most needed. Most of the blood flow to the healthy liver tissue is provided by the portal vein, while hepatocellular carcinoma (HCC) and liver metastasis feed mainly from the liver artery.