Development and Evaluation of a Target-tracking Radiation-therapy System Using a Multileaf Collimator (MLC) Synchronized with Moving Organs

다국어 초록 (Multilingual Abstract)

A target-tracking radiation-therapy (RT) system that tracks the movement of a treatment
target resulting from internal organ movement has been developed, and the system was evaluated
for effectiveness. The developed radiation-therapy system determines the limit of the MLC
(multileaf collimator) movement range with an acquired maximum displacement value of target
movement during the radiotherapy planning stage and moves the MLC to continuously detect
and synchronize the displacement of the abdominal by using a CCD camera monitoring system
during real-time RT treatment. The system consists of a Co-60 teletherapy unit, an abdominal
displacement detection system to correlate the movement of internal organs, and a MLC moving
stage synchronized with the abdominal displacement. The effectiveness of the RT system was
evaluated by analyzing the beam penumbra from the dose distribution on films (Gafchromic EBT)
installed within a moving phantom. Penumbra widths (80%/20%) were measured for the nominal
left (perpendicular to leaf motion) and right (parallel to leaf motion) directions of the x-axis and
the y-axis for a fixed phantom and fixed MLC (3.3 mm/3.5 mm and 3.7 mm/3.1 mm), a moving
phantom and a fixed MLC (9.0 mm/8.2 mm and 9.1 mm/8.8 mm), and a moving phantom and a
moving MLC (3.7 mm/3.5 mm and 3.7 mm/3.8 mm). Percent area deviations of the 100% to 80%
field of the maximum dose for the exposure condition of a fixed phantom and a fixed MLC were
a relatively low value of 0.64% and a relatively high value of 15.04%, as compared to the values
for a moving phantom and a fixed MLC and for a moving phantom and a moving MLC. With
the method to move the MLC by passive synchronization with organ motion, the target-tracking
radiation-therapy system was successfully implemented and was evaluated for performance. In
future studies, various verification processes should be performed prior to the application of the
system in a clinical situation.

참고문헌 (Reference)

1 J. M. Balter, 36 : 167-, 1996

2 S. Shimazu, 46 : 1127-, 2000

3 S. C. Davies, 67 : 1096-, 1994

4 S.Park, Inha University 2007

5 J. C. L. Chow, 33 : 2606-, 2006

6 T. Cheung, 33 : 2912-, 2006

7 K. E. Rosenzweig, 48 : 81-, 2000

8 G. S. Mageras, 60 : 933-, 2004

9 P. Keall, 32 : 942-, 2005

10 D. Tewatia, 33 : 4330-, 2006

11 H. Shirato, 48 : 435-, 2000

12 O. A. Garcia-Garduno, 23 : 90-, 2008

13 E. E. Wilcox, 34 : 1976-, 2007

14 S. M. Vatnitsky, 48 : 643-, 1997

15 B. M. Keller, 34 : 3996-, 2007

16 Hwa Young Lee, "Radiolabeling, Autoradiogram and in Vivo Imaging of an Atherosclerosis Specific-Peptide" 한국물리학회 52 (52): 858-864, 2008

17 정태식, "Determination of Target Motion by Using a Respiration Monitoring Mask for 4-D Radiotherapy" 한국물리학회 53 (53): 845-850, 2008

18 안용찬, "Application of Real-Time Tumor-Tracking and Gated Rdiotherapy System for Unresectable Pancreatic Cancer" 연세대학교의과대학 45 (45): 584-590, 2004

19 William T. Chu, "Accelerators and Medicine" 한국물리학회 50 (50): 1385-1389, 2007