A dosimetric analysis of dose escalation using two intensity-modulated radiation therapy techniques in locally advanced pancreatic carcinoma.
OBJECTIVE
To perform an analysis of three-dimensional conformal radiation therapy (3D-CRT), sequential boost intensity-modulated radiation therapy (IMRTs), and integrated boost IMRT (IMRTi) for dose escalation in unresectable pancreatic carcinoma.


METHODS
Computed tomography images from 15 patients were used. Treatment plans were generated using 3D-CRT, IMRTs, and IMRTi for dose levels of 54, 59.4, and 64.8 Gy. Plans were analyzed for target coverage, doses to liver, kidneys, small bowel, and spinal cord.


RESULTS
Three-dimensional-CRT exceeded tolerance to small bowel in 1 of 15 (6.67%) patients at 54 Gy, and 4 of 15 (26.7%) patients at 59.4 and 64.8 Gy. 3D-CRT exceeded spinal cord tolerance in 1 of 15 patients (6.67%) at 59.4 Gy and liver constraints in 1 of 15 patients (6.67%) at 64.8 Gy; no IMRT plans exceeded tissue tolerance. Both IMRT techniques reduced the percentage of total kidney volume receiving 20 Gy (V20), the percentage of small bowel receiving 45 Gy (V45), and the percentage of liver receiving 35 Gy (V35). IMRTi appeared superior to IMRTs in reducing the total kidney V20 (p < 0.0001), right kidney V20 (p < 0.0001), and small bowel V45 (p = 0.02).


CONCLUSIONS
Sequential boost IMRT and IMRTi improved the ability to achieve normal tissue dose goals compared with 3D-CRT. IMRTi allowed dose escalation to 64.8 Gy with acceptable normal tissue doses and superior dosimetry compared with 3D-CRT and IMRTs.
Brown
Michael W
MW
Radiation Oncology Branch, CCR, National Institutes of Health, Bethesda, MD 20892-1002, USA.
Ning
Holly
H
Arora
Barbara
B
Albert
Paul S
PS
Poggi
Matthew
M
Camphausen
Kevin
K
Citrin
Deborah
D
D002277:Carcinoma / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D004307:Dose-Response Relationship, Radiation; D005240:Feasibility Studies; D006801:Humans; D007421:Intestine, Small / Q000528:radiation effects; D007668:Kidney / Q000528:radiation effects; D008099:Liver / Q000528:radiation effects; D020714:Maximum Tolerated Dose; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000517:prevention & control*; D011859:Radiography; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D013116:Spinal Cord / Q000528:radiation effects