应用Alderson Rando人形体模探讨肺肿瘤位置和体积对正常肺组织剂量学参数影响

目的 探讨肺肿瘤位置、体积对正常肺组织剂量体积参数的影响.方法 将采用组织等效材料制作的模拟球形病灶分别嵌入Alderson Rando人形体模右肺3个叶和左肺下、上叶,采用6MV X线对上述各种情况进行5个野简化调强放疗计划设计,处方剂量为60 Gy(2 Gy/次共30次).所有计划都使99%靶区体积达到处方剂量要求.分析正常肺组织接受不同剂量照射的体积百分比(V_5、V_(10)、V_(20)、V_(30)、V_50)和平均肺剂量.结果 就正常肺组织的各个剂量体积参数而言,不同病灶位置和直径的差异多数是不同的,两种因素对各个参数的变化有不同程度的影响.各个参数随球形病灶直径的增大而增大(P<0.05).当病灶直径从2 cm增至3 cm、病灶位于不同位置时,各参数增幅在3.83%～125.38%范围内;当病灶直径从3 cm增至4 cm、病灶位于不同位置时,各参数增幅在10.46%～51.46%范围内.结论 肺肿瘤位置和直径变化对正常肺组织剂量体积参数多数有不同程度影响,但如何提高预测准确性尚待基础和临床实验的进一步研究.     

Impact of Different Vein Catheter Sizes for Mechanical Power Injection in CT: In Vitro Evaluation with Use of a Circulation Phantom

The purpose of this study was to evaluate the influence of different peripheral vein catheter sizes on the injection pressure, flow rate, injection duration, and intravascular contrast enhancement. A flow phantom with a low-pressure venous compartment and a high-pressure arterial compartment simulating physiological circulation parameters was used. High-iodine-concentration contrast medium (370 mg iodine/ml; Ultravist 370) was administered in the venous compartment through peripheral vein catheters of different sizes (14, 16, 18, 20, 22, and 24 G) using a double-head power injector with a pressure limit of 325 psi. The flow rate was set to 5 ml/s, with a total iodine load of 36 g for all protocols. Serial CT scans at the level of the pulmonary artery and the ascending and the descending aorta replica were obtained. The true injection flow rate, injection pressure, injection duration, true contrast material volume, and pressure in the phantom during and after injection were continuously monitored. Time enhancement curves were computed and both pulmonary and aortic peak time and peak enhancement were determined. Using peripheral vein catheters with sizes of 14–20 G, flow rates of approximately 5 ml/s were obtained. During injection through a 22-G catheter the pressure limit was reached and the flow rate was decreased, with a consecutive decreased pulmonary and aortic contrast enhancement compared to the 14- to 20-G catheters. Injection through a 24-G peripheral vein catheter was not possible because of disconnection of the canula due to the high flow rate and pressure. In summary, intravenous catheters with sizes of 14–20 G are suitable for CT angiography using an injection protocol with a high flow rate and a high-iodine-concentration contrast medium.     

幻肢痛

幻肢现象不仅局限于四肢,身体其他部位被切除时也会发生,其中幻肢痛的发生率约占60%～70%。最近,其发病机制中大脑皮层功能重组和幻肢感、幻肢痛的相关性受到重视,认为很可能是幻肢痛产生的中枢性机制之一。幻肢痛的治疗极为困难,治疗方式多种多样,被证明行之有效的包括药物治疗、神经阻滞治疗、外科治疗、心理疗法等。治疗方案仍然没有统一和定论。     

~(125)I粒子源治疗前列腺癌的剂量分布研究

目的研究放射性125I粒子源治疗前列腺癌的剂量分布。方法采用三维治疗计划系统(3-DTPS)进行实验模拟,前列腺癌用肿瘤模型代替,应用热释光剂量学方法,模拟测量前列腺癌中的剂量分布。结果实验表明,125I粒子源治疗前列腺癌是在不均匀剂量模式下受照,剂量直接与粒子源的数量和几何位置有关。结论125I粒子源表面剂量最高,随着距离增加而剂量迅速下降。粒子源的间距越小瘤内剂量越高。     

Preoperative localization of intracranial lesions with MRI using marking pills

Objective

To describe a simple technique for preoperative surface localization of intracranial lesions.

Methods

11 pills in total, including Alfarol (alfacalcidol) capsules, were affixed to a phantom with adhesive tape and a MRI scan was performed. The visibility of the pills and any spatial errors in determining their locations were evaluated. Between June 2006 and April 2009, we employed Alfarol capsules as a skin marker in MRI in clinical surgical cases.

Results

Alfarol capsules, whose actual size is 5.6 mm in diameter, were identified as a hyperintense spot at a size of 4.2, 4.2, and 4.5 mm in diameter in T1-weighted, T2-weighted, and FLAIR (fluid attenuated inversion recovery) sequence images, respectively. The size discrepancies were within 1.4 mm. The average spatial errors were 0.7, 0.6, and 0.7 mm in T1-weighted, T2-weighted, and FLAIR sequence images, respectively. Other pills were not identified in the MRI scans.During this 35-month period, 8 patients underwent preoperative MRI-guided localization at our institution. There were 5 men and 3 women in whom 8 biopsies were performed. In all cases, the result of the biopsy was positive and useful for the treatment that followed. No perioperative complications were encountered.

Conclusion

Alfarol capsule can be used as an external skin marker. Our simple and inexpensive method is a useful addition to preoperative evaluation of superficial intracranial lesions.