Intrafractional Tumor Motion: Lung and Liver

Hiroki Shirato*, Yvette Seppenwoolde, Kei Kitamura, Rikiya Onimura, Shinichi Shimizu

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

297 Citations (Scopus)


Three-dimensional (3D) dose distribution has been improved by 3D conformation and intensity modulation in external radiotherapy. Interfractional uncertainty has been reduced by image-guided setup techniques. Reduction of ambiguity because of intrafractional target motion is the next step forward. Respiratory organ motion is known to be the largest intrafractional organ motion. Radiotherapy techniques controlling, gating, or tracking respiratory motion are under investigation to use smaller safety margins and higher doses for moving tumors. However, data on intrafractional tumor motion are sparse. We developed a fluoroscopic real-time tracking system and implantation techniques of fiducial markers for moving organs and have been accumulating knowledge about internal tumor motion. We also found the importance of 4-dimensional treatment planning to account for tumor motion in precision radiotherapy. This article reviews the current basic knowledge on respiratory physiology and summarizes the accumulating knowledge on internal motion of lung and liver tumors.

Original languageEnglish
Pages (from-to)10-18
Number of pages9
JournalSeminars in Radiation Oncology
Issue number1
Publication statusPublished - Jan 2004
Externally publishedYes

Bibliographical note

Funding Information:
Supported in part by the grant from Japanese Ministry of Education, Culture, Sports, Science and Technology.


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