Implications of respiratory motion as measured by four-dimensional computed tomography for radiation treatment planning of esophageal cancer.
OBJECTIVE
To evaluate the respiratory motion of primary esophageal cancers and pathologic celiac-region lymph nodes using time-resolved four-dimensional computed tomography (4D CT).


METHODS
Respiration-synchronized 4D CT scans were obtained to quantify the motion of primary tumors located in the proximal, mid-, or distal thoracic esophagus, as well as any involved celiac-region lymph nodes. Respiratory motion was measured in the superior-inferior (SI), anterior-posterior (AP), and left-right (LR) directions and was analyzed for correlation with anatomic location. Recommended margin expansions were determined for both primary and nodal targets.


RESULTS
Thirty patients underwent 4D CT scans at Massachusetts General Hospital for planned curative treatment of esophageal cancer. Measurements of respiratory tumor motion were obtained for 1 proximal, 4 mid-, and 25 distal esophageal tumors, as well as 12 involved celiac-region lymph nodes. The mean (SD) peak-to-peak displacements of all primary tumors in the SI, AP, and LR dimensions were 0.80 (0.45) cm, 0.28 (0.20) cm, and 0.22 (0.23) cm, respectively. Distal tumors were found to have significantly greater SI and AP motion than proximal or mid-esophageal tumors. The mean (SD) SI, AP, and LR peak-to-peak displacements of the celiac-region lymph nodes were 0.92 (0.56) cm, 0.46 (0.27) cm, and 0.19 (0.26) cm, respectively.


CONCLUSIONS
Margins of 1.5 cm SI, 0.75 cm AP, and 0.75 cm LR would account for respiratory tumor motion of >95% of esophageal primary tumors in the dataset. All celiac-region lymph nodes would be adequately covered with SI, AP, and LR margins of 2.25 cm, 1.0 cm, and 0.75 cm, respectively.
Patel
Abhijit A
AA
Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA, USA.
Wolfgang
John A
JA
Niemierko
Andrzej
A
Hong
Theodore S
TS
Yock
Torunn
T
Choi
Noah C
NC
D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy; D004938:Esophageal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy; D005260:Female; D006801:Humans; D015182:Lymphatic Irradiation; D008297:Male; D009068:Movement; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012016:Reference Values; D012119:Respiration; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*