Open AccessComparison of CT images with average intensity projection, free breathing, and mid‐ventilation for dose calculation in lung cancer
Author(s) -
Khamfongkhruea Chirasak,
Thongsawad Sangutid,
Tannata Chirapha,
Chamchod Sasikarn
Publication year - 2017
Publication title -
journal of applied clinical medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.83
H-Index - 48
ISSN - 1526-9914
DOI - 10.1002/acm2.12037
Subject(s) - contouring , nuclear medicine , lung cancer , radiation therapy , radiation treatment planning , maximum intensity projection , medicine , intensity (physics) , breathing , mathematics , radiology , physics , computer science , oncology , angiography , computer graphics (images) , anatomy , quantum mechanics
The purpose of this study was to compare three computed tomography ( CT ) images under different conditions—average intensity projection ( AIP ), free breathing ( FB ), mid‐ventilation (MidV)—used for radiotherapy contouring and planning in lung cancer patients. Two image sets derived from four‐dimensional CT (4 DCT ) acquisition ( AIP and MidV) and three‐dimensional CT with FB were generated and used to plan for 29 lung cancer patients. Organs at risk ( OAR s) were delineated for each image. AIP images were calculated with 3D conformal radiotherapy (3 DCRT ) and intensity‐modulated radiation therapy ( IMRT ). Planning with the same target coverage was applied to the FB and MidV image sets. Plans with small and large tumors were compared regarding OAR volumes, geometrical center differences in OAR s, and dosimetric indices. A gamma index analysis was also performed to compare dose distributions. There were no significant differences ( P > 0.05) in OAR volumes, the geometrical center differences, maximum and mean doses of the OAR s between both tumor sizes. For 3 DCRT , the gamma analysis results indicated an acceptable dose distribution agreement of 95% with 2%/2 mm criteria. Although, the gamma index results show distinct contrast of dose distribution outside the planning target volume ( PTV ) in IMRT , but within the PTV , it was acceptable. All three images could be used for OAR delineation and dose calculation in lung cancer. AIP image sets seemed to be suitable for dose calculation while patient movement between series acquisition of FB images should be considered when defining target volumes on 4 DCT images.