Abstract：Objective To explore the correlation between the respiration-induced clinical target volume (CTV) motion and volume variation and the dosimetric variation of planning target volume (PTV) and organs at risk (OAR) during free-breathing (FB) with whole breast intensity-modulated radiotherapy (IMRT). Methods Seventeen patients with breast conserving surgery underwent respiration-synchronized four-dimentional computed tomography (4DCT) simulation scans on the state of FB. The treatment plan was constructed using the end-inspiration phase scan, then copied and applied to the other respiratory phases. The dose distribution was calculated separately to evaluate the dose-volume histograms parameters for the PTV, ipsilateral lung and heart. Results During FB, the CTV motion vector was (2.09±0.74) mm, and the volume variation was (3.05±0.94)%. There was no correlation between the volume variation of CTV and dosimetric variation of PTV/OAR (r=－0.390－0.480,P=0.182－0.775). In anteroposterior (AP), superoinferior (SI) and vector directions, the CTV movement correlated well with the PTV mean dose, conformal index, and the lung volume receiving high dose (V20, V30, V40, and V50;r=－0.975－0.791,P=0.000－0.041). In SI and vector directions, the CTV displacement only correlated with the heart volume receiving>5 Gy (V5)(r=－0.795,0.687,P=0.006,0.028). The lung volume variation and the lung volume receiving high dose correlated reasonably well (r=0.655－0.882,P=0.001－0.040).The heart volume variation only correlated with the V5 of heart (r=－0.701,P=0.024). Conclusions During free-breathing, the effect of breast volume variation can be ignored for whole breast IMRT, and whole breast IMRT assisted with breath-hold may improve the accuracy of dose delivery during radiotherapy.
WANG Wei,LI Jian-bin,HU Hong-guang et al. The dosimetric study of the targets and organs at risk in whole breast forward intensity-modulated radiotherapy during free breathing based on 4DCT[J]. Chinese Journal of Radiation Oncology, 2012, 21(4): 357-360.
[1] Topolnjak R, Sonke JJ, Nijkamp J, et al. Breast patient setup error assessment:comparison of electronic portal image devices and cone-beam computed tomography matching results. Int J Radiat Oncol Biol Phys,2010,78:1235-1243. [2] 王玮,李建彬.保乳术后外照射靶区位移的确定与校正.中华放射肿瘤学杂志,2011,20:259-262. [3] Wu Q, Mohan R, Morris M, et al. Schmidt-Ullrich R.Simultaneous integrated boost intensity-modulated radiotherapy for locally advanced head-and-neck squamous cell carcinomas. Ⅰ:dosimetric results. Int J Radiat Oncol Biol Phys,2003,56:573-585. [4] Baltas D, Kolotas C, Geramani K, et al. A conformal index (COIN) to evaluate implant quality and dose specification in brachytherapy. Int J Radiat Oncol Biol Phys,1998,40:515-524. [5] Oozeer R, Chauvet B, Garcia R, et al. Dosimetric evaluation of conformal radiotherapy:conformity factor. Cancer Radiother,2000,4:207-216. [6] Pignol JP, Olivotto I, Rakovitch E, et al. A multicenter randomized trial of breast intensity-modulated radiation therapy to reduce acute radiation dermatitis. J Clin Oncol,2008,26:2085-2092. [7] McDonald MW, Godette KD, Butker EK, et al. Long-term outcomes of IMRT for breast cancer:a single-imtitution cohort analysis．Int J Radiat Oncol Biol Phys,2008,72:1031-1040． [8] Kinoshita R, Shimizu S, Taguchi H, et al. Three-dimensional intrafractional motion of breast during tangential breast irradiation monitored with high-sampling frequency using a real-time tumor-tracking radiotherapy system. Int J Radiat Oncol Biol Phys,2008,70:931-934. [9] Richter A, Sweeney R, Baier K, et al. Effect of breathing motion in radiotherapy of breast cancer:4D dose calculation and motion tracking via EPID. Strahlenther Onkol,2009,185:425-430. [10] Qi XS, White J, Rabinovitch R, et al. Respiratory organ motion and dosimetric impact on breast and nodal irradiation. Int J Radiat Oncol Biol Phys,2010,78:609-617. [11] Wang X, Pan T, Pinnix C, et al. Cardiac motion during deep-inspiration breath-hold:implications for breast cancer radiotherapy. Int J Radiat Oncol Biol Phys,2012,In press. [12] Qi XS, Hu A, Wang K, et al. Respiration induced heart motion and indications of gated delivery for left-sided breast irradiation. Int J Radiat Oncol Biol Phys, 2012,In press. [13] Weiss E, Wijesooriya K, Dill SV, et al. Tumor and normal tissue motion in the thorax during respiration:analysis of volumetric and positional variations using 4DCT. Int J Radiat Oncol Biol Phys,2007,67:296-307. [14] Darby SC, McGale P, Taylor CW, et al. Long-term mortality from heart disease and lung cancer after radiotherapy for early breast cancer:prospective cohort study of about 300,000 women in US SEER cancer registries. Lancet Oncol,2005,6:557-565. [15] Zurl B, Stranzl H, Winkler P, et al. Quantitative assessment of irradiated lung volume and lung mass in breast cancer patients treated with tangential fields in combination with deep inspiration breath hold (DIBH). Strahlenther Onkol,2010,186:157-162. [16] Cover KS, Lagerwaard FJ, Senan S. Color intensity projections:a rapid approach for evaluating four-dimensional CT scans in treatment planning. Int J Radiat Oncol Biol Phys,2006,64:954-961． [17] 李建彬,王巾帼,卢杰,等.乳腺癌保乳术后自主呼吸控制全乳腺调强放疗靶区勾画与靶区位移.中华放射医学与防护杂志,2009,29:58-60.
2012, Vol. 21 
