Thayer School of Engineering, Dartmouth College, Hanover, United States.
DoseOptics LLC, Lebanon, United States.
Radiother Oncol. 2021 Jul;160:90-96. doi: 10.1016/j.radonc.2021.04.013. Epub 2021 May 1.
In mono-isocentric radiation therapy treatment plans designed to treat the whole breast and supraclavicular lymph nodes, the fields meet at isocenter, forming the match line. Insufficient coverage at the match line can lead to recurrence, and overlap over weeks of treatment can lead to increased risk of healthy tissue toxicity. Cherenkov imaging was used to assess the accuracy of delivery at the match line and identify potential incidents during patient treatments.
A controlled calibration was constructed from the deconvolved Cherenkov images from the delivery of a modified patient treatment plan to an anthropomorphic phantom with introduced separation and overlap. The trend from this calibration was then used to evaluate the field match line for accuracy and inter-fraction consistency for two patients.
The intersection point between matching field profiles was directly correlated to the distance (gap/overlap) between the fields (anthropomorphic phantom R = 0.994 "breath hold" and R = 0.990 "free breathing"). The profile intersection points from two patients' imaging sessions yielded an average of +1.40 mm offset (overlap) and -1.32 mm offset (gap), thereby introducing roughly a 25.0% over-dose and a -23.6% under-dose (R = 0.994).
This study shows that field match regions can be detected and quantified by taking deconvolved Cherenkov images and using their product image to create steep intensity gradients, causing match lines to stand out. These regions can then be quantitatively translated into a dose consequence. This approach offers a high sensitivity detection method which can quantify match line variability and errors in vivo.
在设计用于治疗整个乳房和锁骨上淋巴结的单等中心放射治疗计划中，射野在等中心处交汇，形成吻合线。吻合线处覆盖不足可能导致复发，而在数周的治疗中重叠可能导致健康组织毒性增加。切伦科夫成像被用于评估吻合线处的投递准确性，并在患者治疗期间识别潜在事件。
从经过解卷积的切伦科夫图像中构建了一个受控校准，该图像是将修改后的患者治疗计划传输到带有引入的分离和重叠的人体模型上的结果。然后，使用该校准的趋势来评估两个患者的场吻合线的准确性和分次间一致性。
匹配场轮廓的交点与场之间的距离（间隙/重叠）直接相关（人体模型 R = 0.994“呼吸暂停”和 R = 0.990“自由呼吸”）。从两个患者的成像会话中获得的轮廓交点平均产生+1.40 毫米的偏移（重叠）和-1.32 毫米的偏移（间隙），从而引入了大约 25.0%的超剂量和-23.6%的低剂量（R = 0.994）。
这项研究表明，可以通过拍摄解卷积的切伦科夫图像并使用其乘积图像创建陡峭的强度梯度来检测和量化场吻合区域，从而使吻合线突出。然后可以将这些区域定量转化为剂量后果。这种方法提供了一种高灵敏度的检测方法，可以量化吻合线的变异性和体内误差。
