Hinai Satoki, Usui Keisuke, Obara Yusuke, Maebayashi Toshiya, Ookubo Satoshi, Ichikawa Atsushi, Sasaki Yoshihisa, Ozawa Kazuo
Department of Central Radiology, Nihon University Itabashi Hospital, Tokyo, Japan.
Department of Radiological Technology, Faculty of Health Science, Juntendo University, Tokyo, Japan; Department of Radiation Oncology, Faculty of Medicine, Juntendo University, Tokyo, Japan.
Med Dosim. 2025;50(2):141-147. doi: 10.1016/j.meddos.2024.11.001. Epub 2025 Jan 7.
This study was conducted to evaluate the use of 4-dimensional (4D) maximum intensity projection (4D-MIP) to compensate for the disadvantages of average intensity projection (AIP), which is used to determine the internal target volume (ITV) in lung tumors. A respiratory motion phantom with a simulated tumor was imaged using 4D computed tomography (4D-CT). AIP and 4D-MIP were generated based on 10 phases of 4D-CT, followed by contouring of the ITV and ITV; these were compared with the ITV contoured in 10 phases of 4D-CT (ITV). Additionally, the profile curves of the ITV and ITV were obtained, and the full width at half maximum (FWHM) was measured. There was no significant difference between the ITV and ITV; however, the ITV demonstrated a lower value. The FWHM values of the ITV were smaller than those of ITV owing to decreased CT values in the superior-inferior margin. 4D-MIP may contribute to improving the consistency of the ITV delineation.
