Purpose: It has been shown that in cases of lung tumors close to the liver cupola, the four dimensional (4D)-CT postprocessing maximum intensity projection (MIP) algorithm does not fully recover the radiotherapy internal gross tumor volume (IGTV). In this work, a semiautomatic technique was evaluated by which the residual IGTV that was not included into the IGTV by MIP algorithm was actually added. Methods: A moving phantom and five selected patients were considered. The various IGTVs produced by the semiautomatic approach were compared to those generated by 4D-CT manual contouring. Results: In all cases, the radiation oncologist qualitatively concurred with the semiautomatic IGTV. A quantitative difference in volume of 2.6% was found in the phantom study, whereas a mean difference of 0.1±4.6% was obtained in the patient studies. Conclusions: A semiautomatic technique to include the residual part of IGTV covered by liver/spleen cupola when using MIP algorithm was validated on phantom and on selected patients, revealing the possibility of defining the IGTV for patients with lesions located near liver/spleen cupola by performing only the contours on the MIP series.
- internal gross tumor volume-IGTV
- internal target volume-ITV
- lung node, radiotherapy-RT
- maximum intensity projection-MIP
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging