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 Centermzhang@mdanderson.org