| Budget Amount *help |
¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000)
Fiscal Year 2014: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2013: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2012: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
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| Outline of Final Research Achievements |
The efficacy of four-dimensional computed tomography (4DCT) before stereotactic body radiotherapy (SBRT) for peripheral lung tumors was evaluated. The amplitude of a fiducial marker implanted near a lung tumor was measured using the maximum intensity projection (MIP) method in 4DCT imaging acquired before SBRT and compared with that measured during SBRT using real-time tumor-tracking radiotherapy (RTRT) system. In the lower lobe, the mean discrepancy from the amplitude measured with 4DCT to the mean of maximum amplitude of the patient during SBRT was 5.7 ± 8.0 mm, 12.5 ± 16.7 mm, 6.8 ± 8.5 mm in the LR, CC, and AP direction, respectively. 4DCT MIP before SBRT underestimates the maximum amplitude during actual SBRT. Caution must be paid to determine the margin with 4DCT especially for tumors in the lower lobe. More research is needed to establish a new method for gated radiotherapy using multiple gating points.
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