AbstractID: 9478 Title: Time-integrated Dose Volume Histogram (TDVH), a new
paradigm for plan evaluation
We propose a new concept of time-integrated dose volume histogram (TDVH). TDVH is a
quantity defined to account for the transient motion of a volume of interest (either target or organs
at risk) during treatment in the treatment plan evaluation. The DVH and dose distribution analyses
have been commonly used to evaluate the quality of a plan in terms of target coverage and
normal tissue sparing. However, due to static characteristics its significance decreases as the
magnitude of intra-fraction patient motion increases. The DVH for planning target volume (PTV)
has another issue. Two similar DVH for the PTV with different planning margins will have a very
different interpretation for the CTV coverage. The TDVH concept overcomes this problem. The
TDVH is calculated for the CTV and each organ-at-risk volume by convolving the three
dimensional patient motion with the 3-D dose matrix computed on volumetric planning CT data
set. The 3-dimensional motion of a volume of interest (VOI) during treatment can be easily
monitored using a commercially available patient setup and monitoring system. We have
developed an algorithm to calculate time-integrated dose matrix, which is then used to compute
TDVH. We present a simple benchmark test to demonstrate the difference between DVH and
TDVH and show the clinical utility of this new concept.