AUTHOR=Du Qing-Hua , Li Jian , Gan Yi-Xiu , Zhu Hui-Jun , Yue Hai-Ying , Li Xiang-De , Ou Xue , Zhong Qiu-Lu , Luo Dan-Jing , Xie Yi-Ting , Liang Qian-Fu , Wang Ren-Sheng , Liu Wen-Qi 

TITLE=Potential Defects and Improvements of Equivalent Uniform Dose Prediction Model Based on the Analysis of Radiation-Induced Brain Injury

JOURNAL=Frontiers in Oncology

VOLUME=11

YEAR=2022

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2021.743941

DOI=10.3389/fonc.2021.743941

ISSN=2234-943X

ABSTRACT=<sec><title>Purpose</title><p>To study the impact of dose distribution on volume-effect parameter and predictive ability of equivalent uniform dose (EUD) model, and to explore the improvements.</p></sec><sec><title>Methods and Materials</title><p>The brains of 103 nasopharyngeal carcinoma patients treated with IMRT were segmented according to dose distribution (brain and left/right half-brain for similar distributions but different sizes; V<italic><sub>D</sub></italic> with different <italic>D</italic> for different distributions). Predictive ability of EUD<sub>V</sub><italic><sub>D</sub></italic> (EUD of V<italic><sub>D</sub></italic>) for radiation-induced brain injury was assessed by receiver operating characteristics curve (ROC) and area under the curve (AUC). The optimal volume-effect parameter <italic>a</italic> of EUD was selected when AUC was maximal (mAUC). Correlations between mAUC, <italic>a</italic> and <italic>D</italic> were analyzed by Pearson correlation analysis. Both mAUC and <italic>a</italic> in brain and half-brain were compared by using paired samples <italic>t</italic>-tests. The optimal D<italic><sub>V</sub></italic> and V<italic><sub>D</sub></italic> points were selected for a simple comparison.</p></sec><sec><title>Results</title><p>The mAUC of brain/half-brain EUD was 0.819/0.821 and the optimal <italic>a</italic> value was 21.5/22. When <italic>D</italic> increased, mAUC of EUD<sub>V</sub><italic><sub>D</sub></italic> increased, while <italic>a</italic> decreased. The mAUC reached the maximum value when <italic>D</italic> was 50–55 Gy, and <italic>a</italic> was always 1 when D ≥55 Gy. The difference of mAUC/<italic>a</italic> between brain and half-brain was not significant. If <italic>a</italic> was in range of 1 to 22, AUC of brain/half-brain EUD<sub>V55 Gy</sub> (0.857–0.830/0.845–0.830) was always larger than that of brain/half-brain EUD (0.681–0.819/0.691–0.821). The AUCs of optimal dose/volume points were 0.801 (brain D<sub>2.5 cc</sub>), 0.823 (brain V<sub>70 Gy</sub>), 0.818 (half-brain D<sub>1 cc</sub>), and 0.827 (half-brain V<sub>69 Gy</sub>), respectively. Mean dose (equal to EUD<sub>V</sub><italic><sub>D</sub></italic> with <italic>a</italic> = 1) of high-dose volume (V<sub>50 Gy</sub>–V<sub>60 Gy</sub>) was superior to traditional EUD and dose/volume points.</p></sec><sec><title>Conclusion</title><p>Volume-effect parameter of EUD is variable and related to dose distribution. EUD with large low-dose volume may not be better than simple dose/volume points. Critical-dose-volume EUD could improve the predictive ability and has an invariant volume-effect parameter. Mean dose may be the case in which critical-dose-volume EUD has the best predictive ability.</p></sec>