Journal List > Prog Med Phys > v.24(3) > 1098388

Shin, Chung, Kim, Son, Yoon, Lim, and Lee: The Development of Real Time Automatic Patient Position Correction System during the Radiation Therapy Based on CCD: A Feasibility Study

Abstract

Upon radiation treatment, it is the important factor to monitor the patient's motion during radiation irradiated, since it can determine whether the treatment is successful. Thus, we have developed the system in which the patient's motion is monitored in real time and moving treatment position can be automatically corrected during radiation irradiation. We have developed the patient's position monitoring system in which the patient's position is three dimensionally identified by using two CCD cameras which are orthogonal located around the isocenter. This system uses the image pattern matching technique using a normalized cross-correlation method. We have developed the system in which trigger signal for beam on and off is generated by quantitatively analyzing the changes in a treatment position through delivery of the images taken from CCD cameras to the computer and the motor of moving couch can be controlled. This system was able to automatically correct a patient's position with the resolution of 0.5 mm or less.

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Fig. 1.
Schematic diagram for algorithm of automatic patient position correction system software and hardware.
pmp-24-191f1.tif
Fig. 2.
Schematic diagram for H/W connection for automatic patient position correction system.
pmp-24-191f2.tif
Fig. 3.
Pattern matching example. (left) pattern matching circle point marker for x-y plane, (right) pattern matching circle point marker for z-axis.
pmp-24-191f4.tif
Fig. 4.
The home made 3D moving phantom for automatic position correction system and CCD camera holder.
pmp-24-191f3.tif
Fig. 5.
Schematic diagram for 3D modeling of the 3D moving couch for heavy moving phantom motion correction verification.
pmp-24-191f5.tif
Table 1.
The result of rectal cancer patient treatment setup position difference of between before treatment and after treatment.
Patient Lateral (cm) Longitudinal (cm) Vertical (cm)
Mean±SD Max Mean±SD Max Mean±SD Max
1 0.115±0.135 0.5 0.07±0.103 0.3 0.18±0.144 0.5
2 0.329±0.199 0.7 0.194±0.241 0.6 0.206±0.139 0.5
3 0.433±0.319 1.0 0.167±0.161 0.5 0.339±0.301 1.2
4 0.222±0.236 0.7 0.089±0.137 0.5 0.094±0.106 0.4
5 0.387±0.219 0.7 0.187±0.219 0.8 0.207±0.258 0.6
Average 0.297±0.222 0.72 0.141±0.172 0.54 0.205±0.189 0.64
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