Guevara Nicolas, Atean Ibrahim, Benoit David, Pointreau Yoann, Angellier Gaëlle, Marcie Serge, Saaï Sonia, Gnansia Dan, Thariat Juliette
Department of Head and Neck Surgery, University Center-Institut Universitaire de la Face et du Cou, 33 Av. Valombrose, 06189, Nice Cedex 2, France,
Eur Arch Otorhinolaryngol. 2015 Jul;272(7):1597-603. doi: 10.1007/s00405-014-2949-y. Epub 2014 Mar 7.
The aim of this study was to assess dose attenuation by a Digisonic SP cochlear implant (CI) and evaluate its impact on treatment planning. The Digisonic CI was irradiated with 6 MV photons. Overall dose attenuation was assessed with MOSFET dosimeters and Gafchromic films. In addition, we evaluated the attenuation of separate CI components. Dose attenuation was also calculated using different radiation treatment planning systems (TPS) softwares and dose calculation algorithms. The CI was placed on a head phantom. Single-beam and multiple-beam plans were evaluated for dose attenuation using two radiation techniques (Conformal and Stereotactic radiotherapy) and four different algorithms (Clarkson, Point Kernel-Superposition, Ray Tracing and Monte Carlo). MOSFET and Gafchromics film showed maximal 6-7.5% radiation dose attenuation, at the center of the CI. Computerized TPS-based dose attenuation by the implant was 4-8.1%, using a single ipsilateral field. No clinically meaningful dose attenuation was found in multiple field plans owing to the contribution of various beam paths with only a couple going through the implant using either conventional conformal or stereotactic treatment plans. Dose attenuation induced by a Digisonic SP CI is about 6%, for single 6 MV photon field. This dose reduction is unlikely to be clinically significant, as single-field radiotherapy plans to this anatomic region are uncommon.
本研究的目的是评估Digisonic SP型人工耳蜗（CI）的剂量衰减情况，并评估其对治疗计划的影响。用6兆伏光子对Digisonic CI进行照射。使用MOSFET剂量计和Gafchromic胶片评估总体剂量衰减。此外，我们还评估了CI各个组件的衰减情况。还使用不同的放射治疗计划系统（TPS）软件和剂量计算算法计算剂量衰减。将CI放置在头部模型上。使用两种放射技术（适形放疗和立体定向放疗）和四种不同算法（克拉克森算法、点核叠加算法、射线追踪算法和蒙特卡罗算法）评估单束和多束计划的剂量衰减情况。MOSFET和Gafchromics胶片显示，在CI中心处，辐射剂量最大衰减6 - 7.5%。使用单个同侧野时，基于计算机TPS的植入物引起的剂量衰减为4 - 8.1%。在多野计划中，由于各种射线路径的贡献，只有少数几条射线通过植入物（使用传统适形或立体定向治疗计划），因此未发现具有临床意义的剂量衰减。对于单个6兆伏光子野，Digisonic SP CI引起的剂量衰减约为6%。这种剂量减少在临床上不太可能具有显著意义，因为针对该解剖区域的单野放射治疗计划并不常见。
