Quantification of radiation-induced lung damage with CT scans: The possible benefit for radiogenomics

Abstract

Background. Radiation-induced lung damage (RILD) is an important problem. Although physical parameters such as the mean lung dose are used in clinical practice, they are not suited for individualised radiotherapy. Objective, quantitative measurements of RILD on a continuous instead of on an ordinal, semi-quantitative, semi-subjective scale, are needed. Methods. Hounsfi eld unit (HU) changes before versus three months post-radiotherapy were correlated per voxel with the radiotherapy dose in 95 lung cancer patients. Deformable registration was used to register pre-and post-CT scans and the density increase was quantifi ed for various dose bins. The dose-response curve for increased HU was quantifi ed using the slope of a linear regression (HU/Gy). The end-point for the toxicity analysis was dyspnoea Ն grade 2. Results. Radiation dose was linearly correlated with the change in HU (mean R 2 ϭ 0.74 Ϯ 0.28). No differences in HU/Gy between groups treated with stereotactic radiotherapy, conventional radiotherapy alone, sequential or concurrent chemoradiotherapy were observed. In the whole patient group, 33/95 (34.7%) had dyspnoea Ն G2. Of the 48 patients with a HU/Gy below the median, 16 (33.3%) developed dyspnoea Ն G2, while in the 47 patients with a HU/Gy above the median, 17 (36.1%) had dyspnoea Ն G2 (not signifi cant). Individual patients showed a nearly 21-fold difference in radiosensitivity, with HU/Gy ranging from 0 to 10 HU/Gy. Conclusions. HU changes identify objectively the whole range of individual radiosensitivity on a continuous, quantitative scale. CT density changes may allow more robust and accurate radiogenomics studies.

Should breathing adapted radiotherapy also be applied for right-sided breast irradiation?

“…Although there was a change in the PFTs, they were still within the normal range [25]. In lung cancer patients, who were treated with (chemo-)radiation, a change in the density of the Houndfields Units (HU) on CT, before and after 3 months of irradiation, seemed to predict dyspnea grade 2 [17]. This ''radionomics'' approach could be interesting to investigate in breast cancer patients.…”

“…In the literature, three pulmonary side effects are described: the risk of radiation pneumonitis, decrease in pulmonary function, and the risk of secondary lung cancer [13][14][15][16][17][18][19][20][21][22][23][24][25].…”

Texture analysis of medical images for radiotherapy applications

“…6 Although most parts of the works in this context faced the detection of RILI by the evaluation of simple CT ; Pota et al, 2015 103 CRT, chemoradiotherapy; DCE-MRI, dynamic contrast-enhanced MRI; EBRT, external beam radiotherapy; IMRT, intensity-modulated radiotherapy; mp-MRI, multiparametric MRI; PET, positron emission tomography; RT, radiotherapy; SABR, stereotactic ablative radiation therapy; SRT, stereotactic radiotherapy; T2w, T 2 weighted. density, [76][77][78] Mattonen et al [79][80][81] proposed texture analysis for an automatic classification of tumour recurrence and lung injuries. They found a radiomic signature consisting of five textural features (minimum grey level, grey-level uniformity, GLCM homogeneity, GLCM correlation and GLCM energy) after stereotactic ablative radiation therapy (SABR) in consolidative and periconsolidative regions.…”

Imaging-Based Treatment Adaptation in Radiation Oncology

“…Consequently, the risk of RILT may decrease when lung subvolumes with high 18 F-FDG uptake are avoided by applying dedicated radiation planning techniques. A similar study investigated the potential of CT imaging to measure RILT (54). Here, changes in the Hounsfield units of CT scans acquired before and 3 mo after radiotherapy were correlated with RILT.…”