Establishment and verification of a displacement model for the solitary pulmonary lesion based on 4D-CT technology / 中华放射肿瘤学杂志

ABSTRACT

Objective:To measure the displacement of the solitary pulmonary lesion (SPL) located in different pulmonary segments based on 4D-CT technology (4DCT) and to establish and verify a relevant mathematical model of tumor displacement.Methods:The modeling samples of 290 SPLs were subject to both 4DCT and active breath control (ABC) spiral CT scans. The tumor displacement in different pulmonary segments was measured based on 4DCT images. The tumor volume was obtained by contouring the gross tumor volume (GTV) on ABC spiral CT images. The diaphragm movement was measured by X-ray simulator. The vital capacity and tidal volume were gained by pneumatometer. The baseline data, such as gender, age, height, weight, respiratory rate, and tumor lobe and segment where tumors were located, were collected. Multivariate linear regression was used to analyze the correlation between the 3D-tumor displacement and gender, age, height, weight, respiratory rate, tumor location, volume and diaphragm movement. The displacement model was established based on the modeling sample of 290 cases. Then, it was verified by comparing the tumor displacement derived from the model with that of 4DCT technology based on the randomly selected 17 SPLs.Results:The displacement model for tumors located in the upper lobe was established as Xup=-0.267+0.002TV+0.446DM, Yup=-1.704+0.004TV+0.725DM+2.250SII+1.349SIII and Zup=0.043+0.626DM+0.599SII+0.519SIII. The displacement model of the middle lobe tumors was Xmid=0.539+0.758DM, Ymid=-2.316+2.707DM+0.009TV and Zmid=0.717+1.112DM. The displacement model for tumors located in the lower lobe was Xlow=-0.425+0.004TV+0.857DM, Ylow=4.691+4.817DM+0.005TV-0.307RR+3.148SIX+2.655SX and Zlow=0.177+0.003TV+0.908DM.(DM diaphragm movement, TV tidal volume, RR respiratory rate, SII posterior segment, SIII anterior segment, SIX lateral basal segment, SX posterior basal segment). There was no significant difference between two results derived from the displacement model and 4DCT technology.( P>0.05). Conclusions:The diaphragm movement and tidal volume are the main influencing factors of 3D lung tumor displacement. The tumor displacement in the superior-inferior direction is correlated with different pulmonary segments of the upper and lower lobes. The displacement of tumors located in different segments of middle lobes is similar. The displacement model can predict the displacement of SPLs located in different lobes, providing reference for individualized delineation of PTV.