Multi-institutional comparison of intensity modulated radiation therapy (IMRT) planning strategies and planning results for nasopharyngeal cancer.
The intensity-modulated radiation therapy (IMRT) planning strategies for nasopharyngeal cancer among Korean radiation oncology facilities were investigated. Five institutions with IMRT planning capacity using the same planning system were invited to participate in this study. The institutions were requested to produce the best plan possible for 2 cases that would deliver 70 Gy to the planning target volume of gross tumor (PTV1), 59.4 Gy to the PTV2, and 51.5 Gy to the PTV3 in which elective irradiation was required. The advised fractionation number was 33. The planning parameters, resultant dose distributions, and biological indices were compared. We found 2-3-fold variations in the volume of treatment targets. Similar degree of variation was found in the delineation of normal tissue. The physician-related factors in IMRT planning had more influence on the plan quality. The inhomogeneity index of PTV dose ranged from 4 to 49% in Case 1, and from 5 to 46% in Case 2. Variation in tumor control probabilities for the primary lesion and involved LNs was less marked. Normal tissue complication probabilities for parotid glands and skin showed marked variation. Results from this study suggest that greater efforts in providing training and continuing education in terms of IMRT planning parameters usually set by physician are necessary for the successful implementation of IMRT.
Park
Sung Ho
SH
Department of Radiation Oncology, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, Korea.
Park
Hee Chul
HC
Park
Suk Won
SW
Oh
Do Hoon
DH
Choi
Youngmin
Y
Kim
Jeung Kee
JK
Ahn
Yong Chan
YC
Park
Won
W
Suh
Hyun Sook
HS
Lee
Rena
R
Bae
Hoonsik
H
D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D010306:Parotid Gland / Q000528:radiation effects; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012062:Relative Biological Effectiveness; D012867:Skin / Q000528:radiation effects; D047368:Tumor Burden; D055815:Young Adult