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Objective: 4D-CT technology to determine advanced non-small cell lung cancer (NSCLC) within the target volume (internal the gross target The volume IGTV4D and IGTVGating) between conventional the 3DCRT plan and 4D plans respiratory gating (Gating) program target volume and geometric and dosimetric benefits related dosimetric differences, evaluation of the 4D-CT technology to explore its clinical significance in non-small cell lung cancer radiation therapy used in the late. Methods: 15 patients with advanced non-small cell lung cancer patients in advance of normal breathing ordinary 3D unenhanced CT scan, re-4D-CT scan, the CT sequence 10 different respiratory phases. Sweep in ordinary flat sketch on a 3D-CT 3D plan GTV and normal organs; each 4D-CT scanning level 10 breathing phase CT image sequences one by one phase sketch 4D planning IGTV, saved to 4D-CT 20% of the sequence outlined in 20% CT sequence, normal organ; the end expiratory 40%, 50%, 60% three 4D-CT sequence one by one on each scan level phase sketched PTVGating plan IGTV, Save to the sequence of the 4D-CT 50% 50% CT sequence sketched normal organs. The use of three-dimensional treatment planning system according the PTV3D, PTV4D and the PTVGating, designed three sets of radiation treatment planning for each patient: 3D plans, 4D plans Gating plan. The contrast CT PTV3D by ordinary level outlined GTV isotropic external expansion 1.5cm, including subclinical lesions, breathing exercises and equipment error (tumors of the lower lobe of the head and tail direction expansion 2.0cm); PTV4D 4D-CT 10 outlined in the CT image sequences individually IGTV, coupled with superior directional external expansion 1.0cm, including subclinical lesions and equipment errors; PTVGating by end-expiratory 40%, 50%, 60% three 4D- CT sequence individually when each scan level sketched IGTV, plus fine isotropic external expansion 1.0cm, including subclinical lesions and equipment error. The three sets of plans to the prescription dose, radiation field the same way. Compare three sets of plans in the target volume, dose and normal organ dosimetry differences. Results: GTV4D IGTVgating the average volume were 36.99 Guests 29.68 cm3, 28.57 Guests 23.28 cm3, which decreased by 8.43 soil 12.42 cm3, P = 0.02. PTV3D, PTV4D, the average volume of PTVgating were 205.07 disabilities 87.24cm3, 156.63 Guests 85.03 cm3, 134.73 disabilities 72.04 cm3, followed by decreasing 48.45 soil 31.23 cm3, 70.34 soil 28.76 cm3, 21.89 soil 32.78 cm3 (PTV4D VS PTV3D, PTVgating VS PTV3D PTVgating VS PTV4D), P values ??as follows P = 0.000, P = 0.000, P = 0.022 15 patients PTV3D volume were significantly to greater than PTV4D and PTVgating but three cases appeared PTV3D representing PTV4D omission of some of the target area . The volume of PTV4D the volume greater than PTVgating respiratory gating technology can further reduce the target volume on the basis of the 4D plan. 4D plans the Gating plan in the V5, V20, V30, and lung average by the amount (mean lung dose MLD) compared with 3D plans to lower. Compared with 3D plans, the lung 4D plan V5 from 35.07 ± 15.17% decline to 29.50 ± 14.59%, P = 0.018; the V20 decreased by 16.08 ± 5.45% to 13.29 ± 5.08%, P = 0.001; V30 by 12.97 Guests 4.12 % to 10.72 ± 3.98%, P = 0.001; lung mean dose (mean lung dose MLD) from 1021.20 disabilities 343.15cGy decline to the 848.13 with disabilities 342.66cGy, P = 0.003. Than 3D plans to reduce exposure doses compared with 3D plans the Gating plan in the V5, V20, V30 and MLD. Gating plan lung V5 decreased by 35.07 ± 15.17% to 28.85 ± 14.39%, P = 0.009; the V20 decreased by 16.08 ± 5.45% to 13.05 Guests 5.05%, P = 0.000; V30 decreased from 12.97 ± 4.12% to 10.35 Guests 3.77 %, P = 0.000; MLD from 1021.20 disabilities 343.15cGy decline to the 807.00 with disabilities 316.18cGy, P = 0.001. Compared to the 4D planning, Gating plan V5, V20, V30 and the MLD compared with 4D plan to reduce. The Gating plan V5 by 29.50 ± 14.59% down to 28.85 ± 14.39%, P = 0.103; V20 decreased from 13.29 ± 5.08% to 13.05 Guests 5.05%, P = 0.336; the V30 decreased by 10.72 ± 3.98% to 10.35 ± 3.77%, P = 0.124; MLD decreased by 848.13 disabilities 342.66cGy to the 807.00 with disabilities 316.18cGy, P = 0.062. Conclusions: 3DCRT, 4D planning based on 4D-CT positioning technology to more accurately locate the tumor target boundary, lower respiratory movement of the target; compared with 4D plans, 3D plans exist too expand the target or missing the target District defects; 4D-CT technology can reduce the target volume of ensure target coverage tumor while lower dose and volume of normal tissue exposed to the radiation dose to enhance it possible; gated radiotherapy can be compared with the 4D plan further narrow the target area, and more conducive to the protection of normal tissues.
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