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Integrating dose spatial distribution into radiotoxicity calculation. Ming Zhang Dept. of Bioinformatics & Computational Biology University of Texas M.D. Anderson Cancer Center. Radiotoxicity. Dose volume histogram. Toxicity measured by dose volume (surface) histogram. dose map. DVH. - PowerPoint PPT Presentation
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Integrating dose spatial distribution into radiotoxicity
calculation
Ming Zhang
Dept. of Bioinformatics & Computational BiologyUniversity of Texas M.D. Anderson Cancer Center
Radiotoxicity
Dose volume histogram
Toxicity measured by dose volume (surface) histogram
volu
me
dose (Gy)
dose map DVH
Dose spatial distribution
Dose levels and spatial distribution both affect toxicity
Maximum clusters
2 / 42 ( / )
1( )
1b D D a
p De
probability that the voxel is damaged
dose received at a voxel
local damage function:
Cluster of damaged voxels
Clusters: connected components of damaged voxels
cluster size =1, 1, 1, 1, 1
cluster size =1, 3
maximum cluster
Connectivity
1-connectivity
2-connectivity
Maximum clusters
local damage probability
maximum clusterlocation
maximum cluster size
2648.91
dose map
maximumclustersrendering
Example
DSH(absolute area)
DSH(relative area)
differenceof maximumclusters
Discussions
Maximum clusters describe radiotoxicity by
Incorporating dose spatial distribution into cluster calculation
Working with all dose levels simultaneously
Providing a visualization tool to select treatment plans (location and size of maximum cluster)
Discussions
Local damage function
sigmoidal shape: analytical, piecewise
parameters (patient/organ specific)
Computational complexity
number of iterations in simulation
all possible parameter combinations
Dose component histogram
Dose component histogram
For each dose level d
DVH: sum of all voxels receiving dose d or more
DCH: largest component of organ region receiving dose d or more
Cluster/component connectivity
• Local connectivity (immediate neighborhood)
– 1-connectivity
– 2-connectivity
– n-connectivity
• Regional connectivity (extended neighborhood)
Regional connectivity
Conclusions
Dose spatial distribution should be integrated into radiotoxicity calculation
Connectivity determines cluster/component formation
Maximum cluster
works with all dose levels simultaneously
provides size and location of MC (rendering)
Dose component histogram (DCH)
Incorporates spatial distribution into DVH
Collaborators:
Howard Thames, Ph.D. (MDACC)
Susan Tucker, Ph.D. (MDACC)
Radhe Mohan, Ph.D. (MDACC)
Lei Dong, Ph.D. (MDACC)
Xiaodong Zhang, Ph.D. (MDACC)
Ronald Goldman, Ph.D. (Rice)
Falai Chen, Ph.D. (USTC, China)
Ming Zhang, Ph.D.Department of Bioinformatics &
Computational BiologyUT M.D. Anderson Cancer [email protected]