IMRT或3DCRT计划评估——适形指数(CI)

doi:10.3760/cma.j.issn.1004-4221.2017.10.015

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Abstract Objective To propose a new set of conformity indices (CIs) that may be useful for evaluating whether the prescribed doses to target volume and organs at risk (OAR) in intensity-modulated radiotherapy (IMRT) or three-dimensional conformal radiotherapy (3DCRT) plans meet clinical requirements. Methods A total of 30 patients’ plans were randomly selected from the IMRT or 3DCRT plans for non-small cell lung cancer and analyzed with the newly defined CIs described in this article. The plans to be improved were selected according to the evaluating results, and two schemes were developed to improve these plans. Then, the differences in CI, D_max, D_min, and D_meanof the planning target volume (PTV), V₅ and V₂₀ of the normal lung, V₃₀ and V₄₀ of the heart, and D_max of the spinal cord were investigated with the paired t-test.Results Among the 30 plans, the average volume covered by the prescribed isodose line (V_RI) was 25% larger than the PTV, so the normal lung tissue with a volume approximately 25% of PTVwas given the same dose as the target volume, and the volume covered by the prescribed isodose line in the target V (C) R was only 75% of the volume VR. Ninety-five percent of the target volume received a full prescribed dose;only 5% of the target volume received less than the prescribed dose, but which was still within 90% of the prescribed dose. In the comparison between the original plans and the plans improved using the first scheme, CI₂, CI₄, CI₅, CI₆, and homogeneity index (HI) were not significantly different (P=0.240-0.780), and CI₁ and CI₃ showed significant differences (P=0.002 and 0);D_max, D_min, and D_mean of the PTV, V₅ and V₂₀ of the normal lung, V₃₀ and V₄₀ of the heart, and D_max of the spinal cord were not significantly different (P=0.211-0.964). In the comparison between the original plans and the plans improved using the second scheme, CI₂, CI₄, and CI₅ were not significantly different (P=0.308, 0.308, and 0.106), CI₁, CI₃, CI₆, and HI showed significant differences (P=0.001-0.014);D_max, D_min, and D_mean of the PTV, V₅ and V₂₀ of the normal lung, and D_max of the spinal cord showed significant differences (P=0.008-0.036), and V₃₀ and V₄₀ of the heart were not significantly different (P=0.083 and 0.080). Conclusions The new set of CIs proposed in this paper may be a good tool for evaluating the conformity of the target and the prescribed dose to OAR and thus developing better individualized treatment plans.

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	Articles by authors
	Zhao Man
	Hu Yimin

Key words： Intensity modulated radiotherapy Three-dimensional conformity radiotherapy Conformity index Plan evaluation

Received: 02 March 2017

Corresponding Authors: Hu Yimin,Email:yiminhu888@163.com

Cite this article:

Zhao Man,Hu Yimin. A new set of conformity indices for evaluating intensity-modulated radiotherapy or three-dimensional conformal radiotherapy plans[J]. Chinese Journal of Radiation Oncology, 2017, 26(10): 1177-1181.

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http://journal12.magtechjournal.com/Jweb_fszlx/EN/10.3760/cma.j.issn.1004-4221.2017.10.015 OR http://journal12.magtechjournal.com/Jweb_fszlx/EN/Y2017/V26/I10/1177

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