Takemura Akihiro, Nagano Akira, Kojima Hironori, Ikeda Tomohiro, Yokoyama Noriomi, Tsukamoto Kosuke, Noto Kimiya, Isomura Naoki, Ueda Shinichi, Kawashima Hiroki
Faculty of Health Sciences, Institution of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa 920-0942, Japan.
Division of Radiology, Okayama University Hospital, 2-5-1 Shikatacho, Kitaku, Okayama 700-8558, Japan.
Phys Imaging Radiat Oncol. 2018 May 31;6:77-82. doi: 10.1016/j.phro.2018.05.005. eCollection 2018 Apr.
In adaptive radiotherapy, deformable image registration (DIR) is used to propagate delineations of tumors and organs into a new therapy plan and to calculate the accumulated total dose. Many DIR accuracy metrics have been proposed. An alternative proposed here could be a local uncertainty (LU) metric for DIR results.
The LU represented the uncertainty of each DIR position and was focused on deformation evaluation in uniformly-dense regions. Four cases demonstrated LU calculations: two head and neck cancer cases, a lung cancer case, and a prostate cancer case. Each underwent two CT examinations for radiotherapy planning.
LU maps were calculated from each DIR of the clinical cases. Reduced fat regions had LUs of 4.6 ± 0.9 mm, 4.8 ± 1.0 mm, and 4.5 ± 0.7 mm, while the shrunken left parotid gland had a LU of 4.1 ± 0.8 mm and the shrunken lung tumor had a LU of 3.7 ± 0.7 mm. The bowels in the pelvic region had a LU of 10.2 ± 3.7 mm. LU histograms for the cases were similar and 99% of the voxels had a LU < 3 mm.
LU is a new uncertainty metric for DIR that was demonstrated for clinical cases. It had a tolerance of <3 mm.
在自适应放射治疗中，可变形图像配准（DIR）用于将肿瘤和器官的轮廓传播到新的治疗计划中，并计算累积总剂量。已经提出了许多DIR准确性指标。这里提出的一种替代方法可能是用于DIR结果的局部不确定性（LU）指标。
LU表示每个DIR位置的不确定性，并且专注于均匀密度区域中的变形评估。四个病例展示了LU计算：两个头颈癌病例、一个肺癌病例和一个前列腺癌病例。每个病例都接受了两次用于放射治疗计划的CT检查。
从临床病例的每个DIR计算出LU图。脂肪减少区域的LU分别为4.6±0.9毫米、4.8±1.0毫米和4.5±0.7毫米，而萎缩的左腮腺的LU为4.1±0.8毫米，萎缩的肺肿瘤的LU为3.7±0.7毫米。盆腔区域的肠道的LU为10.2±3.7毫米。这些病例的LU直方图相似，99%的体素的LU<3毫米。
LU是一种用于DIR的新的不确定性指标，已在临床病例中得到验证。它的容差<3毫米。
