Three-dimensional treatment planning using electrocardiographically gated multi-detector row CT.
OBJECTIVE
Information concerning the amount and nature of target motion is essential for the determination of internal margin size. However, there are few published reports outlining the motion with heart and aortic pulsation. We introduce a method for three-dimensional radiation treatment planning (3D-RTP) by using electrocardiographically (ECG) gated spiral scanning with a four-section CT system. We describe a new approach to visualize internal organ motion resulting from cardiac motion with ECG gated multidetector row CT.


METHODS
Five patients with lung or liver tumors were studied with a multidetector row CT system under shallow inspiration breath-holding. With retrospective ECG gating, only data acquired within a predefined interval of the cardiac cycle are used for image reconstruction. All reconstructed image data at diastolic and systolic phases of the cardiac cycle were transferred to the 3D-RTP system. The shift of the internal organs between the cardiac cycles was evaluated.


RESULTS
Cardiac contraction influences anterior thorax, pulmonary peripheral vessels, and liver position, in addition to locations near the heart. Apparent movements more than 5 mm between diastolic and systolic phases were observed in the left ventricle, right atrium, and superior vena cava. Two-phase imaging was useful for showing the movement of internal organs during cardiac contraction under breath-holding.


CONCLUSIONS
Spatial information using ECG-gated CT has the potential to determine the planning target volume of moving lung and liver tumors more precisely than conventional CT planning.
Yamada
Kazunari
K
Department of Radiology, Kobe University Graduate School of Medicine, Kobe, Japan. yamadaka@tenriyorozu-hp.or.jp
Soejima
Toshinori
T
Minami
Toshiaki
T
Yoden
Eisaku
E
Watanabe
Yuichi
Y
Takenaka
Daisuke
D
Imai
Masatake
M
Okayama
Takanobu
T
Fujii
Masahiko
M
Sugimura
Kazuro
K
D003199:Computer Systems; D003964:Diaphragm / Q000000981:diagnostic imaging; D004867:Equipment Design; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008099:Liver / Q000000981:diagnostic imaging; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D008168:Lung / Q000000981:diagnostic imaging; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D009038:Motion; D009200:Myocardial Contraction; D010063:Ovum; D011651:Pulmonary Artery / Q000000981:diagnostic imaging; D011667:Pulmonary Veins / Q000000981:diagnostic imaging; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012119:Respiration; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*