Improving Dose Accuracy in Cancer Radiation Therapy Using
Deformable Image Registration
Amy Liu1, Yadin David2,Fred Hosea3, Richard Wu1
1.Department of Radiation Physics,
University of Texas MD Anderson
Cancer Center, Houston, Texas, USA;
2.Biomedical Engineering Consultants,
LLC, Houston, Texas, USA; 3.Convivia,
Oakland, California, USA
摘要Objective To explore the differences in volume and doses to clinical target volumes (CTVs) and
organs at risk (OARs) with and without adaptive treatment plans by using deformable image registration
technology. Methods Ten patients with head and neck cancer were selected for this retrospective study.
Each patient’s original treatment plan was generated using the Eclipse treatment planning system (Varian,
Inc.). Verification CT scans were performed during the third week of treatment. The verification CT images
were registered with the original CT images using the Eclipse rigid registration tool simulating daily
patient treatment alignment. Then, deformable image registrations (Velocity, Inc.) were performed between
the two CT image sets, and the CTVs and major OARs were transferred from the original CT images to
the verification CT images. The original treatment plan was then copied into the verification CT image set
to calculate the radiation dose reflecting the most recent anatomic changes. Verification plan doses were
evaluated by a radiation oncologist, who determined whether an adaptive treatment plan was required.
We compared the accumulated doses to CTVs and OARs between the original and adaptive plans, as
well as between the adaptive and verification plans, to simulate the doses that would have been delivered
if the adaptive plans were not used. All dosimetric data were extracted using the Eclipse Application
Programming Interface tool, which was developed in house to access the Eclipse database. Results Body
contours were different after 3 weeks of treatment. Mean volumes of all CTVs were reduced (P≤0.04),
and the volumes of left and right parotid glands decreased (P≤0.004). There were no significant
differences in the volumes of brainstem and oral cavity (P≥0.14) between the original and verification
CT scans. The spinal cord had a mean 8.7% decrease in volume (P=0.04). Mean doses of CTVs were all
decreased (P≤0.04), whereas the mean doses of the right parotid and oral cavity were increased (P=0.03).
Conclusion Verification CT scans and adaptive planning are required during the course of proton therapy
for patients with head and neck cancer to identify anatomic and dosimetric changes and to ensure adequate
doses to target volumes and safe doses to normal tissues. Our results indicate that deformable image
registration can serve as an essential tool for current proton treatment.
Amy Liu1, Yadin David2,Fred Hosea3, Richard Wu1. Improving Dose Accuracy in Cancer Radiation Therapy Using
Deformable Image Registration[J]. 中国医疗设备, 2016, 31(11): 9-13.
. . China Medical Devices, 2016, 31(11): 9-13.
