SUPERHEATED DROP DETECTORS FOR DOSIMETRY IN RADIOTHERAPY

过热液滴检测器（SDD）由一组过热液滴检测器组成。 悬浮在凝胶中的液滴。 其运作原理与 气泡室的，即，蒸汽气泡的启动， 过热液体中的高能离子。 由于液滴保存在 在“完全光滑”的容器，即另一种液体中，样品可以是 长时间保持过热状态。 它有 已经表明，直接的可读性，简单的准备和 低成本使其在中子剂量测量中具有潜在的应用价值 对于接受高能X射线或电子治疗的患者， 放疗 新的光子敏感SDD最近已经上市 这为剂量测定应用开辟了新的可能性。 该项目的一个主要目标是将SDD技术推广到 检测高于所选线性能量传递（LET）的辐射， 的程度。 在该项目的第一阶段，将开发对光子敏感的SDD， 针对近距离放射治疗的二维和三维剂量测定进行了测试和表征 使用光学断层扫描和MRI来定量表征 探测器中产生的气泡分布。 利用这项新技术， 光子发射近距离放射治疗周围剂量分布的各向异性 将确定放射源，从而能够更好地估计剂量， 患者，从而改善源设计和患者治疗。 的 多源位形模拟中的源-源屏蔽效应 将使用SDD研究临床植入物。 此外，三维 SDD将用于调查定制屏蔽的效果， 近距离放射治疗器。 在该项目的下一阶段，将推广SDD系统， 开发用于测量LET高于指定阈值的辐射， 其在放射治疗模式中的临床应用使用高 能量质子束、中子束、硼中子俘获疗法和 中子近距离治疗;特别注意高剂量 能量质子束用于放射治疗。 该项目的次要具体目标之一是更新 关于现有放射疗法的光中子产额的资料 加速器

The superheated drop detector (SDD) consists of a collection of superheated drops suspended in a gel. Its operation is based on the same principle as that of the bubble chamber; namely, the initiation of vapor bubbles by energetic ions in superheated liquids. Since the drops are kept in a "perfectly smooth" container, i.e. another liquid, the sample can be maintained in a superheated state for a long period of time. It has already been shown that direct readability, simplicity of preparation and low cost make it potentially useful in the measurement of neutron dose equivalent for patients underling high energy x-ray or electron radiotherapy. New photon-sensitive SDDs have recently become available that open up new possibilities for dosimetry applications. A major objective of this project is to generalize the SDD technology to detect radiations above a selected linear energy transfer (LET) by varying the degree of superheat. In the first phase of this project photon-sensitive SDDs will be developed, tested and characterized for 2-and 3-dimensional dosimetry of brachytherapy sources using optical tomography and MRI to quantitatively characterize the bubble distribution produced in the detector. Using this new technology, anisotropy of dose distributions around photon-emitting brachytherapy sources will be determined, thereby permitting better dose estimates to patients and therefore improved source design and patient treatment. The source-to-source shielding effects in multisource configurations simulating clinical implants will be investigated using SDDs. Also, the 3-dimensional SDDs will be used to investigate the effects of customized shields in brachytherapy applicators. In the next phase of this project, the generalized SDD systems will be developed to measure radiations with LET above a specified threshold value, which clinical applications in radiation therapy modalities using high energy proton beam, neutron beams, boron-neutron capture therapy and neutron brachytherapy; with special attention to the dosimetry of high energy proton beams for radiotherapy. One of the secondary specific aims of this project is to update the information on photoneutron yields from currently available radiotherapy accelerators.