Lung cancerComparison of anisotropic aperture based intensity modulated radiotherapy with 3D-conformal radiotherapy for the treatment of large lung tumors
Section snippets
Methods and materials
CT-datasets of 20 patients with Stage I–IV non small cell lung cancer (NSCLC) formed the basis of this study. Specific patient characteristics are presented in Table 1.
The basis for 3D and IMRT plans were thin slice computer tomography (CT) scans acquired on a dedicated 8 slice CT simulator (Somatom Plus 4 Volume Zoom, Siemens®, 120 kV, 200 mAs/section, 10-mm thickness, 10-mm increment. 3D and IMRT plans were generated on PrecisePLAN© 2.03 for a Synergy© linac equipped with a multileaf collimator
Results
As a consequence of identical prescription doses and an emphasis on target coverage, mean target doses were similar for 3D and IMRT (Table 2). Wilcoxon signed rank tests showed that the differences between 3D and 13- and 17-field IMRT, were significant for CTV Dmin (43 Gy vs. 49.1 Gy vs. 48.6 Gy; p < 0.001) and CTV D95 (53.2 Gy vs. 55.0 Gy vs. 55.4 Gy; p = 0.001). GTV- and CTV DVH-metrics were therefore anchored at very similar values. Plan characteristics are therefore mainly based on OAR DVH-metrics.
Discussion
Many dose-escalating trials have been introduced over the past decades in an attempt to improve treatment outcome for patients with advanced NSCLC. Already in the early 70’s, Fletcher’s group reported that dose escalation to between 80 Gy and 100 Gy is necessary to increase local control for lung cancer patients [8], which was recently confirmed in the context of hyperfractionated radiotherapy for stage I and II NSCLC [1], [9]. The following RTOG 83-11 study did not result in improved survival
Conclusion
IMRT reduces lung exposure in patients with large targets compared to 3D-conformal radiotherapy. Anisotropic modulation renders IMRT plans robust toward breathing induced organ motion, effectively preventing interplay effects while not significantly prolonging treatment time.
Conflicts of interest
None.
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Dosimetric and toxicity comparison of IMRT and 3D-CRT of non-small cell lung cancer
2021, Cancer/RadiotherapiePitfalls and Challenges to Consider before Setting up a Lung Cancer Intensity-modulated Radiotherapy Service: A Review of the Reported Clinical Experience
2016, Clinical OncologyCitation Excerpt :The need for increased contouring and planning time, and rigorous quality assurance will probably affect the resources of the radiotherapy department [30]. Although, published data on this in the setting of locally advanced lung cancer are scarce, treatment times will probably be shorter, leading to greater treatment machine availability with VMAT, when compared with tomotherapy or IMRT [30,72,73]. Quite a few trials involving IMRT for lung cancer are in progress.
Intensity-modulated radiotherapy for lung cancer: Current status and future developments
2014, Journal of Thoracic OncologyCitation Excerpt :Apart from treatment time, there is no clear benefit for one technique above the others. All groups comparing standard IMRT techniques with VMAT found a treatment time advantage in favor of VMAT.10,14,32–35 For example, Ong et al.13 showed an 8-minute time reduction if VMAT was used compared to IMRT.