Abstract Objective To assess the differences in delineation of organs at risk (OAR) and dosimetry between junior and senior physicians during intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC) and to evaluate the role of specific training in reducing the differences. Methods Sixteen patients newly diagnosed with NPC were selected in the study. The OAR was delineated separately by three junior physicians and three senior physicians, and the geometric and dosimetric differences were assessed relative to the reference OAR. Delineation was performed again for the two OARs with the biggest difference after specific training in the two groups of physicians, and the differences were evaluated again. The difference was determined by paired t test. Results The maximum dose differences (Dmax) of OAR in the junior and senior physicians were (2.33±12.06)%(－48.06%—137.82%) and (0.09±4.72)%(－49.54%—42.96%), respectively (P=0.039), and the difference in the optic chiasm was the greatest ((5.85±19.63)%∶(1.36±4.64)%,P=0.042). The mean dose differences (Dmean) of OAR in the junior and senior physicians were (3.10±8.07)%(－46.76%—59.76%) and (－0.93±2.03)%(－45.54%—35.69%), respectively (P=0.021), and the difference in the parotid gland was the greatest ((13.23±13.39)%∶(3.20±6.71)%,P=0.002). In the secondary delineation after training, the Dmax of the optic chiasm in the junior and senior physicians was (1.68±3.34)% and (1.50±1.87)%, respectively (P=0.841), and the difference in junior physicians was reduced significantly compared with before training ((1.68±3.34)%∶(5.85±19.63)%,P=0.048);the Dmean of the parotid gland in the junior and senior physicians was (2.46±3.06)% and (1.35±3.00)%, respectively (P=0.274), significantly reduced compared with before training ((2.46±3.06)%∶(13.23±13.39)%,P=0.002;(1.35±3.00)%∶(3.20±6.71)%,P=0.033). Conclusions The differences in delineation of OAR lead to dose uncertainties during IMRT for NPC, and specific training can improve the accuracy of delineation.
Qian Jianjun,Xing Pengfei,Lu Xueguan et al. Differences in delineation of organs at risk lead to dose uncertainties during intensity-modulated radiotherapy for nasopharynx carcinoma[J]. Chinese Journal of Radiation Oncology, 2014, 23(3): 239-243.
Qian Jianjun,Xing Pengfei,Lu Xueguan et al. Differences in delineation of organs at risk lead to dose uncertainties during intensity-modulated radiotherapy for nasopharynx carcinoma[J]. Chinese Journal of Radiation Oncology, 2014, 23(3): 239-243.
[1] Lobefalo F, Bignardi M, Reggiori G, et al. Dosimetric impact of inter-observer variability for 3D conformal radiotherapy and volumetric modulated arc therapy:the rectal tumor target definition case[J]. Radiat Oncol,2013,8:176-186. [2] Ltgendorf-Caucig C, Fotina I, Stock M, et al. Feasibility of CBCT-based target and normal structure delineation in prostate cancer radiotherapy:multi-observer and image multi-modality study[J]. Radiother Oncol,2011, 98:154-161. [3] Jameson MG, Holloway LC, Vial PJ, et al. A review of methods of analysis in contouring studies for radiation oncology[J]. J Med Imag Radiat Oncol,2010,54:401-410. [4] Li XA, Arthur DW, Buchholz TA, et al. Variability of target andnormal structure delineation for breast cancer radiotherapy:an RTOG multi-institutional and multiobserver study[J]. Int J Radiat Oncol Biol Phys,2009,73:944-951. [5] Hall WH, Guiou M, Lee NY, et al. Development and validation of a standardized method for contouring the brachial plexus:preliminary dosimetric analysis among patients treated with IMRT for head-and-neck cancer[J]. Int J Radiat Oncol Biol Phys,2008,72:1362-1367. [6] Saarnak AE, Boersma M, van Bunningen BNFM, et al. Inter-observer variation in delineation of bladder and rectum contours for brachytherapy of cervical cancer[J]. Radiother Oncol,2000,56:37-42. [7] Collier DC, Burnett SSC, Amin M, et al. Assessment of consistency in contouring of normal-tissue anatomic structures[J]. J Appl Clin Med Phys,2003,4:17-24. [8] Ballivy O, Parker W, Vuong T, et al. Impact of geometric uncertainties on dose distribution during intensity modulated radiotherapy of head-and-neck cancer:the need for a planning target volume and a planning organ-at-risk volume[J]. Curr Oncol,2006,13:108-115. [9] Hanna GG, Hounsell AR, O′Sullivan JM, et al. Geometrical analysis of radiotherapy target volume delineation:a systematic review of reported comparison methods[J]. Clin Oncol,2010,22:515-525. [10] Breunig J, Hernandez S, Lin J, et al. A system for continual quality improvement of normal tissue delineation for radiation therapy treatment planning[J]. Int J Radiat Oncol Biol Phys,2012,83:703-708. [11] Nelms BE, Tomé WA, Robinson G, et al. Variations in the contouring of organs at risk:test case from a patient with oropharyngeal cancer[J]. Int J Radiat Oncol Biol Phys,2012,82:368-378.
2014, Vol. 23 
