Treatment plan evaluation using dose-volume histogram (DVH) and spatial dose-volume histogram (zDVH)

Area of Science:

• Radiation Oncology
• Medical Physics
• Radiotherapy Planning

Background:

• The standard dose-volume histogram (DVH) is crucial for evaluating radiotherapy plans but lacks spatial information.
• Three-dimensional (3D) treatment planning requires tools that capture the spatial distribution of radiation dose within a region of interest.

Purpose of the Study:

• To introduce and evaluate the z-dependent dose-volume histogram (zDVH) as a supplement to the DVH.
• To demonstrate the utility of zDVH in providing spatial dose variation information for 3D treatment planning.

Main Methods:

• Calculated 3D dose distributions for lung, breast, and prostate treatment plans.
• Computed standard DVHs for entire volumes and zDVHs for individual computed tomographic (CT) slices.
• Compared DVH and zDVH data to identify differences in dose assessment.

Main Results:

• zDVH revealed significant dose concentrations near the central axis in lung irradiation, necessitating plan modification.
• For breast irradiation, zDVH identified high-dose regions and cold spots in specific CT planes, information not evident from DVH alone.
• In prostate treatment, zDVH pinpointed superior hot-spot regions in the bladder and rectum, highlighting potential complication risks.

Conclusions:

• zDVH offers differential dose-volume information relative to CT slice position, complementing the averaged data from DVH.
• zDVH serves as a 2D analog to 3D DVH, providing superior insights in certain scenarios.
• The integration of zDVH with DVH enhances radiotherapy plan evaluation and aids in correlating radiation outcomes.