Four-dimensional measurement of intrafractional respiratory motion of pancreatic tumors using a 256 multi-slice CT scanner.
OBJECTIVE
To quantify pancreas and pancreatic tumor movement due to respiratory motion using volumetric cine CT images.


METHODS
Six patients with pancreatic tumors were scanned in cine mode with a 256 multi-slice CT scanner under free breathing conditions. Gross tumor volume (GTV) and pancreas were manually contoured on the CT data set by a radiation oncologist. Intrafractional respiratory movement of the GTV and pancreas was calculated, and the results were compared between the respiratory ungated and gated phases, which is a 30% duty cycle around exhalation.


RESULTS
Respiratory-induced organ motion was observed mainly in the anterior abdominal side than the posterior side. Average GTV displacement (ungated/gated phases) was 0.7 mm/0.2mm in both the left and right directions, and 2.5mm/0.9 mm in the anterior, 0.1 mm/0mm in the posterior, and 8.9 mm/2.6mm in the inferior directions. Average pancreas center of mass displacement relative to that at peak exhalation was mainly in the inferior direction, at 9.6mm in the ungated phase and 2.3mm in the gated phase.


CONCLUSIONS
By allowing accurate determination of the margin, quantitative analysis of tumor and pancreas displacement provides useful information in treatment planning in all radiation approaches for pancreatic tumors.
Mori
Shinichiro
S
Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan. shinshin@nirs.go.jp
Hara
Ryusuke
R
Yanagi
Takeshi
T
Sharp
Gregory C
GC
Kumagai
Motoki
M
Asakura
Hiroshi
H
Kishimoto
Riwa
R
Yamada
Shigeru
S
Kandatsu
Susumu
S
Kamada
Tadashi
T
D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D015656:Respiratory Mechanics / Q000502:physiology*; D014057:Tomography, X-Ray Computed / Q000379:methods*