DYNAMIC FIELD SHAPING/STEREOTACTIC RADIOSURGERY DOSES

动态场整形/立体定向放射外科剂量

基本信息

批准号：
2094830
负责人：
DENNIS D. LEAVITT
金额：
$ 22万
依托单位：
UNIVERSITY OF UTAH
依托单位国家：
美国
项目类别：
财政年份：
1991
资助国家：
美国
起止时间：
1991-05-01 至 1995-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/2094830
关键词：
clinical biomedical equipment computer assisted medical decision making computer simulation densitometry mathematical model neoplasm /cancer radiation therapy neoplasm /cancer radionuclide therapy neoplasm /cancer surgery patient monitoring device phantom model stereoradiography

项目摘要

The circular field defining apertures commonly used in isocentrically focussed high-dose irradiation (termed radiosurgery) used in treatment of surgically inaccessible vascular malformations, benign acoustic neuromas, or other focal neoplasms, are inadequate to deliver a uniform dose to non-spherical lesions and to simultaneously minimize dose to surrounding critical brain tissue. Multiple-isocenter techniques introduce unacceptable dose Inhomogeneity within the target volume and dose inhomogeneity has been identified as the major predictor of complications following stereotactic radiosurgery (SRS). There is clearly a need for improved techniques. Evaluation of lesion shapes In 40 previously treated patients showed that in nearly 2/3 of the cases, dose to normal tissue could have been reduced and target dose uniformity improved by using dynamically shaped irradiation fields continuously conforming to the target shape throughout the treatment-arc sequence. A computer-controlled Dynamic Field Shaping Collimator for small-field radiosurgery is proposed. Four independent jaws, each having translational motion (in-out) and circular rotation (around the target-to-isocenter-axis) modify the field shape of the circular collimator to conform the shape more closely to the target projection at each increment of arc. The mechanical integrity and reproducibility of the collimation system will be investigated. The dosimetric characteristics of the shaped fields will be Investigated by film and water phantom dosimetry. Dose calculation techniques will be developed and verified to correctly predict the dose distribution for each possible arrangement of the four independent jaws and the series of circular-aperture inserts. These calculations will be verified both for fixed-field and arc irradiations using head phantoms and film densitometry. Computer calculation of isodose distributions and dose volume histograms will be used to compare radiosurgery treatment techniques using a single aperture and single isocenter, single or multiple apertures with multiple Isocenters, and single aperture with dynamic field shaping. It is expected, based on simple geometric estimations, that the volume of critical normal brain receiving excessive radiation can be reduced by half. The potential benefit of this work includes improved cure rates and reduced acute and long term complications through Increased dose uniformity throughout the target volume and minimization of dose to critical brain tissue. These techniques may be applicable in 1/2 to 2/3 of all patients treated with SRS.

定义异中心常用的孔的圆形场用于治疗外科手术无法访问的血管畸形，良性声神经瘤，或其他局灶性肿瘤，不足以将均匀剂量输送到非球状病变，并同时最大程度地减少对周围的剂量关键的脑组织。介绍了多种异化技术目标体积内不可接受的剂量不均匀性和剂量不均匀性已被确定为并发症的主要预测指标立体定向放射外科手术（SRS）。显然需要改进的技术。 40例先前治疗的患者的病变形状评估表明在近2/3病例中，对正常组织的剂量可能具有通过动态使用降低和目标剂量均匀性提高形状的辐照场连续符合目标形状在整个治疗序列中。计算机控制的动态场，用于塑造准直仪提出了小场放射外科手术。四个独立下巴，每个下巴有翻译运动（在外）和圆形旋转（周围目标对中心轴）修改圆形准直仪的场形状要更紧密地与每个目标投影保持一致弧的增加。机械完整性和可重复性将研究准直系统。形状场的剂量特征将是通过膜和水幻影剂量测定法调查。剂量计算将开发和验证技术以正确预测剂量四个独立下巴的每个可能安排的分布一系列圆形孔插入。这些计算将是使用头幻象和膜光密度法。等速器分布和剂量体积的计算机计算直方图将用于比较使用放射外科治疗技术单个光圈和单个同中心，单个或多个孔，带有多个同中心和具有动态场塑形的单个光圈。它根据简单的几何估计，可以预期关键的正常大脑接收过度辐射可以减少一半。这项工作的潜在好处包括提高的治愈率并通过增加剂量减少急性和长期并发症整个目标体积均匀性，剂量最小化关键的脑组织。这些技术可能适用于1/2至2/3 在所有接受SRS治疗的患者中。