D-IMRT verification with a 2D pixel ionization chamber: dosimetric and clinical results in head and neck cancer
D-IMRT verification with a 2D pixel ionization chamber: dosimetric and clinical results in head and neck cancer
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DOI：
10.1088/0031-9155/50/19/017
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发表时间：
2005-10-07
影响因子：
3.5
通讯作者：
Peroni, C
中科院分区：
文献类型：
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作者：
Stasi, M;Giordanengo, S;Peroni, C
在意大利意大利都灵的癌症研究和治疗研究所，采用滑动窗口技术的动态调强放射治疗（D-IMRT）目前被应用于头颈部癌症的选定治疗。在目前的工作中，Pixel分段电离室（PXC）已被用于验证四种不同的头颈部癌症的19个字段。该装置由一个32 x 32矩阵的1024平行板电离室排列在一个24 x 24 cm（2）面积的正方形。每个腔室的直径为0.4 cm，高度为0.55 cm;相邻腔室的中心间隔0.75 cm。每个电离室的灵敏体积为0.07 cm（3）。1024个独立的电离室中的每一个都用定制的微电子芯片读出。将PXC在10 cm深度处获得的水中输出因子与其他探测器进行比较，当场尺寸低至3 x 3 cm时，最大差异为1.9%（2）。用PXC和其他两种类型的电离室测量了不同场尺寸的射束轮廓;在3 x 3 cm 2场的20-80%半影区域中的最大一致距离（DTA）为0.09 cm。多叶准直器的叶速度在0.07和2 cm s（-1）之间变化，探测器响应恒定，优于0.6%。当剂量率在0.21和1.21戈伊min（-1）之间变化时，测量PXC的行为;平均差异为0.50%，最大差异为0.96%。使用增强的动态楔形和阶梯状（步骤）IMRT字段获得的字段，PXC已被测试为简单的ID调制光束;与电影的比较给出了0.12厘米的最大DTA。然后使用PXC检查四种不同的头颈部癌症治疗IMRT计划：颈部脉络膜，腮腺，筛骨和颅底。在PXC与胶片和PXC与治疗计划系统的比较中，具有伽马参数的像素数
Dynamic intensity-modulated radiotherapy (D-IMRT) using the sliding-window technique is currently applied for selected treatments of head and neck cancer at Institute for Cancer Research and Treatment of Candiolo (Turin, Italy). In the present work, a PiXel-segmented ionization Chamber (PXC) has been used for the verification of 19 fields used for four different head and neck cancers. The device consists of a 32 x 32 matrix of 1024 parallel-plate ionization chambers arranged in a square of 24 x 24 cm(2) area. Each chamber has 0.4 cm diameter and 0.55 cm height; a distance of 0.75 cm separates the centre of adjacent chambers. The sensitive volume of each single ionization chamber is 0.07 cm(3). Each of the 1024 independent ionization chambers is read out with a custom microelectronics chip.The output factors in water obtained with the PXC at a depth of 10 cm were compared to other detectors and the maximum difference was 1.9% for field sizes down to 3 x 3 cm(2). Beam profiles for different field dimensions were measured with the PXC and two other types of ionization chambers; the maximum distance to agreement (DTA) in the 20-80% penumbra region of a 3 x 3 cm 2 field was 0.09 cm. The leaf speed of the multileaf collimator was varied between 0.07 and 2 cm s(-1) and the detector response was constant to better than 0.6%. The behaviour of the PXC was measured while varying the dose rate between 0.21 and 1.21 Gy min(-1); the mean difference was 0.50% and the maximum difference was 0.96%. Using fields obtained with an enhanced dynamic wedge and a staircase-like (step) IMRT field, the PXC has been tested for simple I D modulated beams; comparison with film gave a maximum DTA of 0.12 cm. The PXC was then used to check four different IMRT plans for head and neck cancer treatment: cervical chordoma, parotid, ethmoid and skull base. In the comparison of the PXC versus film and PXC versus treatment planning system, the number of pixels with gamma parameter