Elastic image mapping for 4-D dose estimation in thoracic radiotherapy.
OBJECTIVE
Demonstrate the path integration of a four-dimensional (4-D) dose distribution onto the 3-D anatomy.


METHODS
A computer-generated 4-D thoracic phantom with a lung tumour was constructed. Eight respiratory phases were generated. A radiotherapy treatment plan was applied to all the phases resulting in a 4-D dose distribution. An elastic image registration algorithm was used to find the vector displacement between all the image elements and the end expiration phase. The path-integrated tissue dose distribution and each component dose distribution were compared with the planned dose distribution.


RESULTS
Numerical path integration was performed to calculate the tissue dose distribution. Loss of tumour coverage was the predominant effect observed with tumour motion in this study. The loss was asymmetric and dependent on the tumour trajectory.


CONCLUSIONS
The elastic image registration allowed an accurate path integration through a 4-D data set to produce an accurate 3-D tissue dose estimate.
Guerrero
Thomas
T
Department of Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA. tguerrero@mdanderson.org
Zhang
Geoffrey
G
Segars
William
W
Huang
Tzeng-Chi
TC
Bilton
Stephen
S
Ibbott
Geoffrey
G
Dong
Lei
L
Forster
Kenneth
K
Lin
Kang Ping
KP
D016477:Artifacts; D001822:Body Burden; D003198:Computer Simulation; D004548:Elasticity; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000532:radiotherapy*; D008954:Models, Biological; D009038:Motion; D009928:Organ Specificity; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D013902:Radiography, Thoracic / Q000379:methods; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012062:Relative Biological Effectiveness; D013909:Thorax / Q000503:physiopathology / Q000528:radiation effects