Basic research for four-dimensional stereotactic radiotherapy: Toward the two-dimensional cell line.
Hokkaido University Graduate School of Medicine
Department of Radiation Medicine
Hiroki Shirato, Professor
Development of stereotactic radiotherapy for static organs (brain or cervical spinal cord)
|Cranial fixation by a stereotactic frame|
|Three-dimentional (3D) radiation treatment planning using CT images|
|Calculating the location of the target with 1.0-mm
accuracy using biplanar radiography
|Focusing a higher radiation dose to the target|
(Shirato H, et al. J Jpn Soc Ther Radiol Oncol 4:149-62, 1992)
Analysis of respiratory movement on the CT images of small lung tumors
All respiratory phases
|This study showed that respiratory movement of the tumors greatly differed between patients.
(Shimizu S, et al. IJROBP 46:1127-33, 2000)
To determine the 3D coordinates of a moving tumor during radiotherapy, there is a need to develop the four-dimensional (4D) treatment planning, incorporating the time factor into 3D treatment planning,
Study of stereotactic irradiation
Can we irradiate a moving tumor at the very moment that the actual 3D coordinates of the tumor coincide with the planned coordinates if the coordinates are continuously calculated by using the method we developed for static organs?
The development of Real-time Tumor-tracking Radiotherapy
|1997||The Education Ministry Grants-in-Aid for Scientific Research (B) “Real-time Tumor-tracking Radiotherapy”|
|1998||Mitsubishi Electronics manufactured the machine.|
|1999||Collaborative researches with clinical departments started.|
(Shirato H, et al. Lancet 353:1331-32, 1999)
Concept of real-time tumor-tracking radiotherapy
The linac is triggered to irradiate the tumor only when the marker is located within the region of the planned coordinates after 0.05 seconds.
Improvement of dose distribution by intercepting radiotherapy
A moving lung phantom measured with X-ray films
|Conventional radiotherapy||Intercepting radiotherapy|
Improvement of treatment accuracy may lead to cure certain diseases.
Results of stereotactic radiotherapy for stageⅠnon-small cell lung cancer in patients who are medically inoperable or who refuse surgery.
(Onimaru R, et al. IJROBP 56:126-135, 2003)
Improvement of treatment accuracy would lead to cure certain diseases.
Results of stereotactic radiotherapy for localized hepatocellular carcinoma in patients who are not eligible for any other treatment or who are with intercurrent other malignancy.
(Kitamura K, et al. IJROBP 56:221-228, 2003)
Proposition of the basic research for 4D stereotactic radiotherapy
- Can we establish cell or animal experimental systems for 4D stereotactic radiotherapy?
- Can we detect the tumor location non-invasively, without insertion of a gold marker?
Overview of the basic research for 4D stereotactic radiotherapy using molecular imaging
The tumor is irradiated only when it is located at the point of observation.
After 18F-Fluorodeoxyglucose (FDG) is administered to a mouse,
a moving tumor is detected at the point of observation.