Abstract:
Objective:To investigate the setup error of patients with spinal bone metastasis under the guidance of cone beam CT ( CBCT ).Methods : A total of 118 patients with spinal metastasis who underwent radiotherapy from June 2017 to June 2024 in Cancer Hospital of Chinese Academy of Medical Sciences were collected, including 17 cases of cervical spine, 62 cases of thoracic spine and 39 cases of lumbar spine.The KV-level CBCT scan was performed using the Accelerator from Elekta and the KV-level CBCT included with the EDGE linear accelerator from Varian. CBCT images were registered with CT reference images using bone window mode.In this study, 973 data were collected and three-dimensional linear errors were recorded respectively.Results : The patients with spinal bone metastasis were grouped by site, height, weight and BMI respectively. It was found that the P value of the patients grouped only by site was < 0.05, which was statistically significant.Conclusion : The set-up errors of the cervical spine in the VRT, LNG and LAT directions were ( 0.13 ± 0.08 ) cm, ( 0.19 ± 0.09 ) cm and ( 0.15 ± 0.06 ) cm, respectively. The setup errors of thoracic vertebrae in ventral-dorsal ( VRT ), cranial-caudal ( LNG ) and left-right ( LAT ) directions were ( 0.19 ± 0.1 ) cm, ( 0.28 ± 0.13 ) cm and ( 0.24 ± 0.14 ) cm, respectively. The setup errors of the lumbar spine in the VRT, LNG and LAT directions were ( 0.21 ± 0.09 ) cm, ( 0.30 ± 0.13 ) cm and ( 0.20 ± 0.08 ) cm, respectively.It is not necessary to extend or narrow the margin according to the BMI of patients with spinal metastasis, but to change the margin according to the location of bone metastasis.
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