ZHU Zheng-fei,XU Zhi-yong,CHEN Lan-fei,et al.Impact of different beam set-up methods on quality of intensity modulated radiation therapy in non-small cell lung cancer[J].Chinese Journal of Radiological Medicine and Protection,2010,30(5):576-579 |
Impact of different beam set-up methods on quality of intensity modulated radiation therapy in non-small cell lung cancer |
Received:December 11, 2009 |
DOI: |
KeyWords:Non-small cell lung cancer Intensity modulated radiation therapy Dosimetry Beam angle Beam number |
FundProject: |
Author Name | Affiliation | E-mail | ZHU Zheng-fei | Department of Radiation Oncology, Cancer Hospital, Department of Oncology, Shanghai Medical college, Fudan University, Shanghai 200032 China | | XU Zhi-yong | Department of Radiation Oncology, Cancer Hospital, Department of Oncology, Shanghai Medical college, Fudan University, Shanghai 200032 China | | CHEN Lan-fei | Department of Radiation Oncology, Cancer Hospital, Department of Oncology, Shanghai Medical college, Fudan University, Shanghai 200032 China | | HU Wei-gang | Department of Radiation Oncology, Cancer Hospital, Department of Oncology, Shanghai Medical college, Fudan University, Shanghai 200032 China | | FAN Min | Department of Radiation Oncology, Cancer Hospital, Department of Oncology, Shanghai Medical college, Fudan University, Shanghai 200032 China | | WU Kai-liang | Department of Radiation Oncology, Cancer Hospital, Department of Oncology, Shanghai Medical college, Fudan University, Shanghai 200032 China | | XIA Bing | Department of Radiation Oncology, Cancer Hospital, Department of Oncology, Shanghai Medical college, Fudan University, Shanghai 200032 China | | FU Xiao-long | Department of Radiation Oncology, Cancer Hospital, Department of Oncology, Shanghai Medical college, Fudan University, Shanghai 200032 China | xlfu1964@126.com |
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Abstract:: |
Objective To investigate whether the change of beam set-up methods will influence the dosimetric quality of intensity modulated radiation therapy (IMRT) for non-small cell lung cancer (NSCLC). Methods Twenty-one stage Ⅰ-Ⅲ NSCLC patients were selected for this study. The technique of step and shoot was used and three different beam set-up methods were chosen for IMRT planning, including IMRT-7 with nine equal-spaced beams angled 0°, 51°, 102°, 153°, 204°, 255°and 306°; IMRT-5 with five equal-spaced beams angled 0°, 72°, 144°, 216°and 288°; and IMRT-5m which was created from IMRT-7 but excluded 2 fields (51°and 102° were omitted if there was lesion in the right lung, while 255°and 306° were excluded if there was lesion in the left lung). The dose constrains of normal lungs for IMRT were set according to V5-V60 of normal lungs obtained from the same patient’s actually treated 3D-CRT dose volume histogram. The prescription dose for IMRT started from 65 Gy, and then escalated or decreased step by step by 2 Gy once a time until the best plan was obtained. Results For normal lung dose, IMRT-5m had lower V5-V25 than the other two groups; but there was no significant difference in V30-V40.IMRT-5 was the worst for V45-V60; and mean lung dose was lowest in IMRT-5m. Dose parameters of esophagus and spinal cord, target conformity index, and total monitor units were all similar among difference plans. IMRT-5m had lowest heart V40 compared to the other two groups. For target heterogeneity index, IMRT-5 was higher than IMRT-7, but there were no significant differences among IMRT-5m,IMRT-5 and IMRT-7. Compared to 3D-CRT, the prescription dose could be increased by (5.1 ±4.6) Gy for IMRT-7, (3.1±5.3) Gy for IMRT-5, and (5.5±4.8)Gy for IMRT-5m. ConclusionFewer beams and modified beam angles could result in similar, even better plan quality. |
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