Interindividual registration and dose mapping for voxelwise population analysis of rectal toxicity in prostate cancer radiotherapy.
OBJECTIVE
Recent studies revealed a trend toward voxelwise population analysis in order to understand the local dose/toxicity relationships in prostate cancer radiotherapy. Such approaches require, however, an accurate interindividual mapping of the anatomies and 3D dose distributions toward a common coordinate system. This step is challenging due to the high interindividual variability. In this paper, the authors propose a method designed for interindividual nonrigid registration of the rectum and dose mapping for population analysis.


METHODS
The method is based on the computation of a normalized structural description of the rectum using a Laplacian-based model. This description takes advantage of the tubular structure of the rectum and its centerline to be embedded in a nonrigid registration-based scheme. The performances of the method were evaluated on 30 individuals treated for prostate cancer in a leave-one-out cross validation.


RESULTS
Performance was measured using classical metrics (Dice score and Hausdorff distance), along with new metrics devised to better assess dose mapping in relation with structural deformation (dose-organ overlap). Considering these scores, the proposed method outperforms intensity-based and distance maps-based registration methods.


CONCLUSIONS
The proposed method allows for accurately mapping interindividual 3D dose distributions toward a single anatomical template, opening the way for further voxelwise statistical analysis.
INSERM, U1099, Rennes F-35000, France and Université de Rennes 1, LTSI, Rennes F-35000, France.
Gaël
G
Dréan
INSERM, U1099, Rennes F-35000, France and Université de Rennes 1, LTSI, Rennes F-35000, France.
Oscar
O
Acosta
INSERM, U1099, Rennes F-35000, France; Université de Rennes 1, LTSI, Rennes F-35000, France; and Département de Radiothérapie, Center Eugène Marquis, Rennes F-35000, France.
Caroline
C
Lafond
INSERM, U1099, Rennes F-35000, France and Université de Rennes 1, LTSI, Rennes F-35000, France.
Antoine
A
Simon
INSERM, U1099, Rennes F-35000, France; Université de Rennes 1, LTSI, Rennes F-35000, France; and Département de Radiothérapie, Center Eugène Marquis, Rennes F-35000, France.
Renaud
R
de Crevoisier
INSERM, U1099, Rennes F-35000, France and Université de Rennes 1, LTSI, Rennes F-35000, France.
Pascal
P
Haigron
D004307:Dose-Response Relationship, Radiation; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008954:Models, Biological; D058958:Organs at Risk / Q000293:injuries / Q000528:radiation effects; D057285:Precision Medicine / Q000379:methods; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000175:diagnosis; D011878:Radiotherapy / Q000009:adverse effects*; D011879:Radiotherapy Dosage; D012007:Rectum / Q000000981:diagnostic imaging* / Q000293:injuries / Q000528:radiation effects*; D014057:Tomography, X-Ray Computed / Q000379:methods