Computed tomography (CT) images acquired during image guided radiation therapy (IGRT) are useful to assess whether interfractional anatomic changes are large enough to warrant adaptive radiation therapy (ART) replanning. In practice, this assessment is a manual process and is subjective and qualitative; the observer determines a need for ART by visually inspecting anatomic changes in the daily CT relative to the original plan CT. In this study, we report an automated ART-assessment technique in which the planned dose is recalculated upon all daily CTs, which in turn are deformably registered to the original plan CT to accumulate dose from delivered fractions and to track changes in dose distribution and dose-volume parameters. Any change beyond defined thresholds can objectively and quantitatively trigger an ART replan. Analyses were performed upon randomly selected head and neck and female-pelvis cases treated using helical tomotherapy. The daily fan-beam MVCTs, acquired immediately prior to delivery of each fraction, the plan CT, plan structure set, and planned sinogram were input to a prototype adaptive-tracking software, within which the single-fraction dose was recalculated upon each daily MVCT using the planned sinogram and the appropriate MVCT-number-to-electron-density table. The obtained daily dose was accumulated on the plan CT based on the registration of the daily MVCT and the plan CT using the prototype software. The commonly used dose-volume parameters (including mean dose and maximum point dose) were plotted for each fraction. Among the cases reviewed, the volume of the primary PTV was observed to steadily decrease over the treatment course, ranging from approximately 7% to 39% of the initial volume. This was accompanied by observable increases in the mean and maximum doses to the PTV. For one head and neck case, a squamous cell carcinoma of the oropharynx prescribed 70 Gy in 35 fractions, a reduced PTV was observed visually after 28 fractions, at which point a new CT and plan were generated for the patient’s remaining 7 fractions. The adaptive analysis of the original plan had identified a PTV decrease of 13% after fraction 11, with a displacement of regional tissues observed; had this adaptive-tracking software been available during the original treatment course, the need for an adaptive plan could have been identified 17 fractions earlier. The automated tracking of fractional and accumulated dose using the prototype software is practical and effective, and can identify the need for ART in an objective and quantifiable manner. The utility of this ART-assessment technique was demonstrated retrospectively on head and neck cases for which the PTV decrease was not immediately apparent through visual inspection of the IGRT CT alone.