PMID- 17298753
OWN - NLM
STAT- MEDLINE
DCOM- 20090924
LR  - 20181201
VI  - 26
IP  - 2
DP  - 2007 Feb
TI  - [Design planning target volumes (PTVs) in intensity-modulated radiotherapy for 
      nasopharyngeal carcinoma].
PG  - 200-3
AB  - BACKGROUND & OBJECTIVE: Intensity-modulated radiotherapy (IMRT) may help to 
      diminish radiation-induced normal tissue damage and improve quality of life of 
      nasopharyngeal carcinoma (NPC) patients. However, highly conformal treatment 
      techniques commonly establish steep dose gradients between tumor and normal 
      tissues, therefore, daily setup variations can significantly compromise the 
      ultimate precision of idealized IMRT delivery. This study was to investigate the 
      setup accuracy of thermoplastic masks used for immobilizing NPC patients treated 
      by simultaneous integrated boost IMRT, and to determine adequate margins to 
      account for those uncertainties. METHODS: Nineteen patients with early stage 
      (T1-2N0M0) NPC received CT scan weekly during their 6-week treatment course of 
      fractionated IMRT. A total of 85 scanning parameters were obtained. The 
      differences in anatomic landmark coordinates in 3-dimensional directions between 
      daily setup and the first day setup were calculated through comparing the CT 
      images with Osiris software. RESULTS: Mean target isocenter translation was 
      (0.89+/-0.69) mm in x-direction, (0.82+/-0.79) mm in y-direction, and 
      (0.95+/-1.24) mm in z-direction. The systematic errors were 0.94 mm, 1.00 mm, and 
      1.32 mm. The random errors were 0.87 mm, 0.80 mm, and 1.04 mm. The mean total 
      magnitude vector of isocenter motion was 1.87 mm; the 95% confidence interval 
      (CI) was 2.03-7.24 mm. CONCLUSION: During IMRT for early stage nasopharyngeal 
      carcinoma, setting appropriate margin of planning target volume (PTV) by widening 
      3 mm from clinical target volume (CTV) in x, y, z directions will be sufficient 
      to compensate for the dosimetric uncertainty of target areas due to patient setup 
      error. The measured data in the present study should enable the user of this kind 
      of thermoplastic mask to assign appropriate margins for the generation of 
      planning target volumes (PTVs).
FAU - Lin, Cheng-Guang
AU  - Lin CG
AD  - State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, PR China.
FAU - Li, Guo-Wen
AU  - Li GW
FAU - Lin, Liu-Wen
AU  - Lin LW
FAU - Wu, Yu-Qi
AU  - Wu YQ
FAU - Xiao, Da-Yi
AU  - Xiao DY
FAU - Zhao, Chong
AU  - Zhao C
FAU - Lu, Tai-Xiang
AU  - Lu TX
FAU - Cui, Nian-Ji
AU  - Cui NJ
LA  - chi
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - China
TA  - Ai Zheng
JT  - Ai zheng = Aizheng = Chinese journal of cancer
JID - 9424852
SB  - IM
MH  - Adult
MH  - Confidence Intervals
MH  - Dose Fractionation, Radiation
MH  - Female
MH  - Humans
MH  - Immobilization
MH  - Male
MH  - Masks
MH  - Middle Aged
MH  - Nasopharyngeal Neoplasms/diagnostic imaging/pathology/*radiotherapy
MH  - Neoplasm Staging
MH  - Radiotherapy Dosage
MH  - Radiotherapy Planning, Computer-Assisted/*methods
MH  - Radiotherapy, Intensity-Modulated/*methods
MH  - Tomography, X-Ray Computed
EDAT- 2007/02/15 09:00
MHDA- 2009/09/25 06:00
CRDT- 2007/02/15 09:00
PHST- 2007/02/15 09:00 [pubmed]
PHST- 2009/09/25 06:00 [medline]
PHST- 2007/02/15 09:00 [entrez]
AID - 1000-467X200702200 [pii]
PST - ppublish
SO  - Ai Zheng. 2007 Feb;26(2):200-3.