In:
Medical Physics, Wiley, Vol. 40, No. 6Part27 ( 2013-06), p. 447-447
Abstract:
Purpose: To (1) investigate the dosimetric impact of interfraction deformable organ motion for high‐risk prostate cancer treatments and (2) compare two coverage‐based planning (CP) techniques with the fixed margin‐based planning (FM). Methods: 19 patients with 8–13 prostate CT images were used to model interfraction deformable organ changes using principal component analysis (PCA). Displacement vector fields (DVFs) that map from each of the 8–13 images to the reference image were analyzed with PCA to determine the dominant eigenmodes, which were then used to predict the synthetic patient geometries for virtual treatment course simulation. For each patient, an intensity modulated radiation therapy (IMRT) plan with zero PTV margin on target structures (CTVprostate and CTV seminalVesicles ) was created, then evaluated by simulating 1000 30‐fraction virtual treatment courses. Each fraction was prostate centroid aligned. Probabilistic metrics, including 5% and 95% percentile DVHs (pDVH) and TCP/NTCP distributions, were computed. Patients whose D98 failed to achieve 95% coverage probability objective D 98,95 〉 =78Gy (CTV prostate ) or D 98,95 〉 =66Gy (CTV seminalVesicles ) were replanned using (1) FM (PTV prostate = CTV prostate + 5mm, PTV seminalVesicles = CTV seminalVesicles + 8mm), (2) CP OM which optimized uniform margins for CTV prostate and CTV seminalVesicles to meet the CP objective, and (3) CP COP which directly optimized coverage‐based objectives for all structures of interest. Results: For zero‐PTV‐margin plans, 0/19 patients satisfied objective D 98,95 for both CTV prostate and CTV seminalVesicles . The selected margins used in FM failed to ensure target coverage for 8/19 patients. 11 CP OM plans and 8 CP COP plans were favored over the other plans by achieving desirable D98,95 while sparing more normal tissues. Conclusion: The dosimetric impact of deformable organ motions for prostate centroid alignment treatment is not insignificant. Coverage‐based treatment planning techniques can produce better plans than FM, while relative advantages of CP OM and CP COP are patient specific. Supported by NIH P01‐CA‐116602 and Philips Medical Systems. Supported by NIH P01‐CA‐116602 and Philips Medical Systems; NIH P01‐CA‐116602 and Philips Medical Systems
Type of Medium:
Online Resource
ISSN:
0094-2405
,
2473-4209
Language:
English
Publisher:
Wiley
Publication Date:
2013
detail.hit.zdb_id:
188780-4
detail.hit.zdb_id:
1466421-5
