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首页> 外文期刊>Radiotherapy and oncology: Journal of the European Society for Therapeutic Radiology and Oncology >Comparison of megavoltage position verification for prostate irradiation based on bony anatomy and implanted fiducials.
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Comparison of megavoltage position verification for prostate irradiation based on bony anatomy and implanted fiducials.

机译：比较基于骨解剖结构和植入基准的前列腺照射兆伏位置验证。

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摘要

PURPOSE: The patient position during radiotherapy treatment of prostate cancer can be verified with the help of portal images acquired during treatment. In this study we quantify the clinical consequences of the use of image-based verification based on the bony anatomy and the prostate target itself.PATIENTS AND METHODS: We analysed 2025 portal images and 23 computed tomography (CT) scans from 23 patients with prostate cancer. In all patients gold markers were implanted prior to CT scanning. Statistical data for both random and systematic errors were calculated for displacements of bones and markers and we investigated the effectiveness of an off-line correction protocol.RESULTS: Standard deviations for systematic marker displacement are 2.4 mm in the lateral (LR) direction, 4.4 mm in the anterior-posterior (AP) direction and 3.7 mm in the caudal-cranial direction (CC). Application of off-line position verification based on the marker positions results in a shrinkage of the systematic error to well below 1 mm. Position verification based on the bony anatomy reduces the systematic target uncertainty to 50% in the AP direction and in the LR direction. No reduction was observed in the CC direction. For six out of 23 patients we found an increase of the systematic error after application of bony anatomy-based position verification.CONCLUSIONS: We show that even if correction based on the bony anatomy is applied, considerable margins have to be set to account for organ motion. Our study highlights that for individual patients the systematic error can increase after application of bony anatomy-based position verification, whereas the population standard deviation will decrease. Off-line target-based position verification effectively reduces the systematic error to well below 1 mm, thus enabling significant margin reduction.
机译：目的：可以借助在治疗过程中获得的门静脉图像来验证前列腺癌放射治疗期间的患者位置。在这项研究中，我们基于骨解剖结构和前列腺靶标本身来量化使用基于图像的验证的临床后果。患者与方法：我们分析了23例前列腺癌患者的2025例门静脉图像和23例计算机断层扫描（CT）扫描结果。在所有患者中，在CT扫描之前都植入了金标记。计算了关于骨骼和标记物位移的随机和系统误差的统计数据，我们研究了离线校正方案的有效性。结果：系统性标记物位移的标准偏差在横向（LR）方向为2.4 mm，在4.4 mm在前后（AP）方向上，在3.7毫米处在尾颅方向（CC）上。基于标记位置的离线位置验证的应用导致系统误差减小到远低于1 mm。基于骨骼解剖的位置验证可将系统目标不确定性在AP方向和LR方向上降低到50％。在CC方向上未观察到减少。在23位患者中，有6位发现在应用基于骨骼解剖的位置验证后系统误差增加了。结论：我们表明，即使基于骨骼解剖进行矫正，也必须设置相当大的余量来考虑器官运动。我们的研究强调，对于个别患者，应用基于骨骼解剖的位置验证后，系统误差可能会增加，而总体标准差会降低。基于离线目标的位置验证可有效地将系统误差减小到1 mm以下，从而显着降低裕度。

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