Radiat Oncol J.  2017 Sep;35(3):274-280. 10.3857/roj.2017.00444.

Gross tumor volume dependency on phase sorting methods of four-dimensional computed tomography images for lung cancer

• Lee SY
• Lim S
• Ma SY
• Yu J

• KMID: 2393558
• DOI: http://doi.org/10.3857/roj.2017.00444

Abstract

PURPOSE
To see the gross tumor volume (GTV) dependency according to the phase selection and reconstruction methods, we measured and analyzed the changes of tumor volume and motion at each phase in 20 cases with lung cancer patients who underwent image-guided radiotherapy.
MATERIALS AND METHODS
We retrospectively analyzed four-dimensional computed tomography (4D-CT) images in 20 cases of 19 patients who underwent image-guided radiotherapy. The 4D-CT images were reconstructed by the maximum intensity projection (MIP) and the minimum intensity projection (Min-IP) method after sorting phase as 40%-60%, 30%-70%, and 0%-90%. We analyzed the relationship between the range of motion and the change of GTV according to the reconstruction method.
RESULTS
The motion ranges of GTVs are statistically significant only for the tumor motion in craniocaudal direction. The discrepancies of GTV volume and motion between MIP and Min-IP increased rapidly as the wider ranges of duty cycles are selected.
CONCLUSION
As narrow as possible duty cycle such as 40%-60% and MIP reconstruction was suitable for lung cancer if the respiration was stable. Selecting the reconstruction methods and duty cycle is important for small size and for large motion range tumors.

Keyword

Four-dimensional computed tomography; Tumor volume; Respiratory-induced organ motion

MeSH Terms

Four-Dimensional Computed Tomography*
Humans
Lung Neoplasms*
Lung*
Methods*
Radiotherapy, Image-Guided
Range of Motion, Articular
Respiration
Retrospective Studies
Tumor Burden*