CT evaluation of patient deep inspiration self‐breath‐holding: How precisely can patients reproduce the tumor position in the absence of respiratory monitoring devices?

Abstract

The aim of the present study was to evaluate the reproducibility of tumor position under patient deep inspiration self-breath-holding in the absence of respiratory monitoring devices, as well as to compare the reproducibility of deep inspiration self-breath-holding on the verbal command of a radiation technologist (Passive mode) with that initiated by patients' own estimation (Active mode). Twenty patients with lung cancer were shown how the tumor and diaphragm move during the respiration cycle. Patients were instructed to hold their breath during deep inspiration and reproduce identical tumor position as well as possible either by the Active mode or by the Passive mode. After patients had practiced self-breath-holding during deep inspiration, a set of three CT scans was obtained for each of the two modes of self-breath-holding (6 CT scans total) to obtain randomly timed images of 2 mm thickness in the vicinity of the tumor. The first three scans were performed during breath-hold using the Active mode, and next three scans were using the Passive mode. Maximum difference in tumor position for the three CT scans was then calculated along three axes: cranial-caudal (C-C); anterior-posterior (A-P); and right-left (R-L). In the 20 patients who underwent analysis of self-breath-holding, mean maximum difference in tumor position obtained under breath-hold using the Active and the Passive modes were: 2.2 and 3.1 mm along the C-C axis; 1.4 and 2.4 mm along the A-P axis; and 1.3 and 2.2 mm along the R-L axis, respectively. These differences in all axes were significantly smaller (p<0.05) for the Active mode than for the Passive mode. Most tumors displayed maximal respiratory movement along the C-C axis, and minimal movement along the R-L axis, but tumors located in the upper lung displayed maximal movement along the A-P axis. Significant correlation (p<0.05) was observed between differences along three axes in either mode of breath-hold. In conclusion, the reproducibility of tumor position under self-breath-holding by patients during deep inspiration after sufficient practice and in the absence of respiratory monitoring devices was satisfactorily accurate, and differences in tumor position were smaller under breath-holding using the Active mode than using the Passive mode. We believe this new technique is likely to prove extremely useful for the irradiation of lung tumors with a small internal margin and for reduced proportion of high-dose irradiated normal lung to total lung volume.

The Use of the Active Breathing Coordinator Throughout Radical Non–Small-Cell Lung Cancer (NSCLC) Radiotherapy

“…Tumour motion can be unrestricted and monitored, with delivery of RT gated to a pre-defined phase of the respiratory cycle [13][14][15] or following the moving tumour [16]. Alternatively motion can be Brock 5 minimized by planning and treating in passive [17][18][19][20][21] or active [22,23] breathhold.…”

Fluctuation in measurements of pulmonary nodule under tidal volume ventilation on four-dimensional computed tomography: preliminary results

“…Forth, we evaluated unidimensional measurements on the transaxial plane. Onishi and coworkers reported that tumors of lower or middle lung often demonstrated the largest respiratory movement along the craniocaudal axis and the smallest along the right-left axis [18]. Reproducible CT data for pulmonary nodules in the lung base must be obtained on coronal multiplanar reformatting plane to detect the largest respiratory movement.…”

High-dose-rate Three-dimensional Conformal Radiotherapy Combined with Active Breathing Control for Stereotactic Body Radiotherapy of Early-stage Non-small-cell Lung Cancer

“…In our study, the PTV mDIBH included an extra 3 mm margin from the GTV to account for the reproducibility of the tumor position during breath holding. The PTV FB required an extra 10 mm in the left-right and anterior-posterior directions, and an additional 15 mm in the cranio-caudal direction, to account for the uncertainty introduced by breathing motions during CT, while these margins may be unnecessarily large to ensure adequate PTV coverage (14,15). The mean PTV decreased by 50%, which significantly reduced the irradiated region in the normal lungs.…”

“…PTV mDIBH contained GTV mDIBH plus 8 mm margins in all directions. All margins contained the 5 mm distance between the GTV and PTV (15).…”