Department of Clinical Oncology, Royal Marsden NHS Foundation Trust, London, UK.
Clin Oncol (R Coll Radiol). 2013 Jan;25(1):66-73. doi: 10.1016/j.clon.2012.06.007. Epub 2012 Jul 12.
To compare the accuracy of fractionated cranial radiotherapy in a standard three-point thermoplastic shell using daily online correction with accuracy in a Gill-Thomas-Cosman relocatable stereotactic frame.
All patients undergoing fractionated radiotherapy for benign intracranial tumours between March 2009 and August 2010 were included. Patients were immobilised in the frame with those unable to tolerate it immobilised in the shell. The ExacTrac imaging system was used for verification/correction. Daily online imaging before and after correction was carried out for shell patients and systematic and random population set-up errors calculated. These were compared with frame patients who underwent standard departmental imaging/correction with fractions 1-3 and weekly thereafter. Set-up margins were calculated from population errors.
Systematic and random errors were 0.3-0.7 mm/° before correction and 0.1-0.2 mm/° after correction in all axes in the frame, and 0.6-1.5 mm/° before correction and 0.1-0.4 mm/° after correction in the shell. Isotropic margins required for patient set-up could be reduced from 2 mm to <1 mm in the frame and from 5 mm to <1 mm in the shell.
Similar set-up accuracy can be achieved in the standard thermoplastic shell as in a relocatable frame despite less precise immobilisation. The use of daily online correction precludes the need for larger set-up margins.
比较使用每日在线校正的标准三点热塑性壳中分次颅放疗的准确性与可移动 Gill-Thomas-Cosman 立体定向框架的准确性。
所有在 2009 年 3 月至 2010 年 8 月期间接受分次放疗治疗良性颅内肿瘤的患者均纳入研究。无法耐受框架固定的患者使用热塑性壳固定。使用 ExacTrac 成像系统进行验证/校正。对壳患者进行每日在线成像前和校正后，并计算系统和随机人群摆位误差。将这些与框架患者进行比较，框架患者在第 1-3 次分期间进行标准部门成像/校正，此后每周进行一次。从人群误差计算摆位边缘。
在框架中，所有轴的校正前和校正后的系统和随机误差分别为 0.3-0.7mm/°和 0.1-0.2mm/°，而在壳中分别为 0.6-1.5mm/°和 0.1-0.4mm/°。患者摆位所需的各向同性边缘可以从框架中的 2mm 减少到<1mm，从壳中的 5mm 减少到<1mm。
尽管固定不太精确，但在标准热塑性壳中可以实现与可移动框架相似的摆位准确性。使用每日在线校正可以避免需要更大的摆位边缘。
