科研之友
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摘要
Background and purpose: Intra-fraction patient motion is incompletely understood and the optimum amount of support or immobilization during stereotactic body radiotherapy (SBRT) is unclear. Rigid immobilization is often advocated, but motion still occurs. In contrast, we deliver the vast majority of SBRT using simple supporting devices, simultaneously emphasizing comfort, frequent position checks and progressive reduction in treatment times. We report spine stability during lung SBRT. Materials and methods: Patients lie on a thin mattress with arms supported above their head and below-knee support. Stereoscopic spine X-rays before and after fraction delivery identified motion in three translational and three rotational directions. %26lt;br%26gt;Results: Images from 109 fractions in 30 patients resulted in 327 translational and 327 rotational pre- and post-fraction comparisons. Mean RapidArc (R) delivery time for variable fraction dose was 4.2 min (SD = 1.4). 92% and 97% of translational and rotational differences were %26lt;= 1 mm and %26lt;= 1 degrees in any direction and 98% of translational differences were %26lt;= 1.5 mm. Mean vertical, longitudinal and lateral motion was 0 mm (SD = 0.4), 0 mm (0.6) and 0 mm (0.6). 84% and 94% of the 109 fractions were delivered with %26lt;= 1 and %26lt;= 1.5 mm translation in all three directions and 93% with %26lt;= 1 degrees of rotation. Two patients accounted for 10/17 fractions with %26gt;1 mm translational motion. %26lt;br%26gt;Conclusions: Based on pre and post-fraction X-ray imaging during fast lung SBRT, simple support devices can result in spine stability that is comparable to that reported with rigid external immobilization.
- 出版日期2012-7
