A novel correction factor based on extended volume to complement the conformity index

Jin, Fang; Wang, Y; Yz, Wu

doi:10.1259/bjr/27949149

Cited by 4 publications

(1 citation statement)

References 21 publications

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“…A conformity index, defined in Equation 1 , 15 , 16 was used to measure the target dose conformity.

where, TV RI was the target volume covered by the reference isodose (95%), V RI was the volume covered by the reference isodose (95%), and TV was the target volume.…”

Section: Methodsmentioning

confidence: 99%

Impact of CT slice thickness on volume and dose evaluation during thoracic cancer radiotherapy

Luo

Jin

et al. 2018

CMAR

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IntroductionAccurate delineation of targets and organs at risk (OAR) is required to ensure treatment efficacy and minimize risk of normal tissue toxicity with radiotherapy. Therefore, we evaluated the impacts of computed tomography (CT) slice thickness and reconstruction methods on the volume and dose evaluations of targets and OAR.Patients and methodsEleven CT datasets from patients with thoracic cancer were included. 3D images with a slice thickness of 2 mm (2–CT) were created automatically. Images of other slice thickness (4–CT, 6–CT, 8–CT, 10–CT) were reconstructed manually by the selected 2D images using two methods; internal tumor information and external CT Reference markers. Structures and plans on 2–CT images, as a reference data, were copied to the reconstructed images.ResultsThe maximum error of volume was 84.6% for the smallest target in 10–CT, and the maximum error (≥20 cm3) was 10.1%, 14.8% for the two reconstruction methods, internal tumor information and external CT Reference, respectively. Changes in conformity index for a target of <20 cm3 were 5.4% and 17.5% in 8–CT. Changes on V30 and V40 of the heart were considerable. In the internal tumor information method, volumes of hearts decreased by 3.2% in 6–CT, while V30 and V40 increased by 18.4% and 46.6%.ConclusionThe image reconstruction method by internal tumor information was less affected by slice thickness than the image reconstruction method by external CT Reference markers. This study suggested that before positioning scanning, the largest section through the target should be determined and the optimal slice thickness should be estimated.

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“…A conformity index, defined in Equation 1 , 15 , 16 was used to measure the target dose conformity.

where, TV RI was the target volume covered by the reference isodose (95%), V RI was the volume covered by the reference isodose (95%), and TV was the target volume.…”

Section: Methodsmentioning

confidence: 99%

Impact of CT slice thickness on volume and dose evaluation during thoracic cancer radiotherapy

Luo

Jin

et al. 2018

CMAR

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Analysis of different evaluation indexes for prostate stereotactic body radiation therapy plans: conformity index, homogeneity index and gradient index

Cao

Dai

Ding

et al. 2019

Precision Radiation Oncology

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Objective:This study analyzed different definitions of the conformity index (CI), homogeneity index (HI), and gradient index (GI) used in evaluation of prostate cancer stereotactic body radiation therapy. Methods:A total of 10 patients with localized prostate cancer staged T1-T2a were selected randomly, from which two stereotactic body radiation therapy plans were designed with CyberKnife and EDGE systems for each patient based on the same images and contours. CI, HI, and GI with different definitions were calculated based on a dose-volume histogram of treatment plans. Results:For four definitions of CI, the results showed that the values calculated by the Radiation Therapy Oncology Group, Lomax and Scheib, and Van't Riet were closer to 1 for EDGE plans, except for that by the Saint-Anne, Lariboisiere, and Tenon group. Meanwhile, CI values of Van't Riet et al were lower than other definitions, which showed high accuracy to describe the conformity between the target volume and prescribed isodose line. For five definitions of HI, CyberKnife plans showed lower values than EDGE plans. HI calculated based on the D 2 (D 5 ) and D 98 (D 95 ) were lower than that calculated by the D max to D min , whereas the standard deviation was higher than others. For the dose GI, the results of effective radius and modified GI showed that EDGE plans had a steeper dose fall-off, which is inverse to the conventional GI. Conclusions:These indexes can all be objective tools for the evaluation of plan quality. Our results showed better conformity of dose distribution and dose gradient for EDGE plans, but better uniformity for CyberKnife plans. The conformation number and S-index were recommended to accurately describe the conformity and uniformity of dose distribution. The ∆R iso and modified GI were also recommended to calculate the dose gradient. K E Y W O R D Sconformity, dose gradient, homogeneity, plan quality, stereotactic body radiotherapy

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Standard-Deviation Based Conformity Index for Evaluating Treatment Plan of Intensity Modulated Radiotherapy in Lung Cancer

Qingya¹,

Yizhong²,

Fuke³

et al. 2022

Radiation Protection Dosimetry

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This paper attempts to find a new conformity index (CI) calculation method with slice and angle information for evaluating lung cancer radiation treatment plan. A total of 20 lung cancer patients in 2016–2019 were selected. Treatment plans were made for each patient. Parameters used in the process of making treatment plans were set the same. The CI and the standard-deviation based CI (SDCI) that contains angle and slice information were calculated. Comparison of results calculated with SDCI and CI were made. The results of the two methods for the patients showed the same trend. Different shapes of simulated dose distribution line shows SDCI can provide more detail information about the target area. Special shapes of simulated dose distribution line for SDCI showed inaccuracy in angle information. The parameter SDCI has more advantage towards the traditional CI for it can provide angle and slice information. However, more angles need to be calculated.

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A novel correction factor based on extended volume to complement the conformity index

Cited by 4 publications

References 21 publications

Impact of CT slice thickness on volume and dose evaluation during thoracic cancer radiotherapy

Impact of CT slice thickness on volume and dose evaluation during thoracic cancer radiotherapy

Analysis of different evaluation indexes for prostate stereotactic body radiation therapy plans: conformity index, homogeneity index and gradient index

Standard-Deviation Based Conformity Index for Evaluating Treatment Plan of Intensity Modulated Radiotherapy in Lung Cancer

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