三维治疗计划系统模拟全身照射的应用研究

目的:采用三维治疗计划系统(3D-TPS)模拟计算全身照射(TBI)的剂量分布.材料和方法:对于全身照射,设置源皮距(SSD)为380 cm,射野大小为40 cm×40 cm,光栏角度为45°,采用自制大水箱测量了直线加速器8 MV光子线水中的百分深度剂量(PDD)和离轴比(OAR).上述相同照射条件下,在3D-TPS中进行水体模的PDD和OAR的模拟计算并与之测量结果进行对比,确认3D-TPS是否能够模拟计算TBI的剂量分布.采用3D-TPS计算人形体模的TBI剂量分布,采用剂量胶片和热释光测量对计算结果进行了比较和确认.结果:对于水体模中的百分深度量和离轴比,3D-TPS的模拟计算结果与大水箱的测量结果最大误差分别为3%和6%左右.对于人形体模的模拟计算,3D-TPS的模拟计算结果与胶片和热释光的测量结果基本符合.结论:3D-TPS可以较准确地模拟计算全身照射的剂量分布.通过3D-TPS对每个特定病人制作相应补偿块,为更均匀剂量的全身照射治疗提供了可能.     

全身放疗中“校准孔法”肺屏蔽技术应用

目的：介绍一种全身照射中以“校准孔法”确定肺挡块位置的方法,并评价其应用效果。方法：在固定肺挡块的泡沫塑料模板上镂一方孔,将射野光野灯透过该方孔的投影,作为调整、校正肺挡块的位置的参照。对8例病人拍片验证,测量胸片上肺与挡块投影的偏差并与传统挡肺方法比较。结果：“校准孔法”肺挡铅在头足方向和身体侧向偏差均小于传统方法。结论：“校准孔法”是一种简单有效的提高全身照射肺屏蔽精度的技术,实用性强,值得进一步研究推广。     

肺屏蔽块对全身照射剂量分布的影响

目的：探讨全身照射（ＴＢＩ）中为控制肺剂量所采用肺屏蔽挡块对剂量分布的影响。方法：利用三维自动扫描水箱按实际ＴＢＩ照射条件测量三种厚度不同的肺铅挡块下，水模体中剂量分布情况。结果：加肺档块使纵膈区剂量减少，肺挡因子与测量的深度有关。结论：肺挡因子应在照射条件下测量。在全身照射总剂量与肺部限受剂量相差较大时，应注意纵膈剂量的修正。     

23例X线全身照射患者的照射方法及剂量学分析

目的:报道23例全身照射患者的照射方法,并对照射中的实时监测结果进行剂量学分析.方法:采用6MV X线对23例患者行前后对穿野分次全身照射治疗,并在照射中用多通道半导体剂量计对晶体、肺、腹部、睾丸、膝五个部位进行剂量实时监测.结果:晶体、肺、腹部、睾丸、膝五个部位的平均受照剂量分别为445.28 cGy、614.26 ...     

全身皮肤电子束照射中剂量监测的意义

目的：通过对全身皮肤电子束照射(TSEI)的急性毒性反应的观察，分析热释光(TLD)剂量监测的临床意义。材料与方法：1995年12月至2002年12月利用Varian Clinac2100C电子直线加速器的6MeV电子束高剂量率治疗模式(HDTSe 6MeV)治疗9例患者，利用热释光剂量计测量剂量累积因子MF．利用电离室测量不同厚度散射屏的皮肤表面剂量及治疗深度，对治疗中的8个患者进行18个解剖部位的TLD剂量监测，治疗周剂量5Gy～6Gv。结果：测得的MF值为2．7。不同厚度散射屏的皮肤表面剂量及治疗深度分别为87．5％～96％、13．5mm～6．5mm。全身皮肤电子束照射对皮肤T细胞淋巴瘤可得到良好的控制效果；急性毒性反应限于皮肤及附属器、手足．热释光监测结果与急性反应相符．结论：通过剂量的测量，可以准确给予患者处方刺量，指导临床根据病变的分期选择适当的散射屏，疗中TLD剂量监测对手指、足背防护及治疗后头项．腋下、会阴、足底补量照射有指导意义，对肥胖患者应行大腿内侧补量。     

用不同剂量率全身照射技术的临床应用

目的：探讨用直线加速器不同剂量率全身照射技术的可行性。方法：采用直线加速器8MV—X射线。不同剂量率分次全身照射方案对9例白血病患者进行了骨髓移植前的预处理照射，用瑞典Seanditronix公司生产的DPD-12通道快速测量系统及其应用软件进行实时剂量监测。结果：检测结果显示符合临床要求，白血病患者全部骨髓移植成功。结论：本方法既避免放射性肺炎的发生，又降低了机器的损耗。     

多通道剂量测量仪在调强放疗剂量检测中的应用

目的：保证调强放疗治疗计划临床实施的正确性。方法：分别用0coy、50cGy、100cGy、150cGy、200cGy、250cGy、300cGy照射多通道剂量仪金属氧化物半导体场效应晶体管（MOSFET）探头,观察多通道剂量仪读数;大机架分别旋转0、30、60、90、120、150、180、210、240、270、300度时,计划照射探头100coy时,观察多通道剂量仪读数;采用多通道剂量仪验证空间多点绝对剂量。结果：计划剂量与多通道剂量仪探头阈值电压之间呈正相关关系（r=l,P=-0．0000）：计划剂量与多通道剂量仪探头读数剂量之间呈正相关关系,（r=1,P=0．0000）;测得多通道剂量仪MOSFET探头,轴方向性误差〈2％：在模体中测量绝对剂量,等中心点实测剂量与计划剂量误差在3％以内,其它偏离点的实测剂量与计划剂量误差在5％以内。结论：应用多通道剂量仪测量IMRT绝对剂量是可行的．可有效地保证IMRT的顺利开展。     

一种用于全身照射技术的全身模拟定位CT扫描与图像重建方法

目的：探索一种适用于全身照射（TBI）的CT重建方法,可同体位连续扫描后获得一套完整的全身模拟定位CT。方法：使用TBI CT重建方法对患者进行CT模拟定位,完成后于Eclipse v15.5计划系统中生成一套全身模拟定位CT,将其运用到TBI计划设计与评估。在应用过程中,基于Python系统开发出相应的图像重建软件,与手动图像重建结果进行对比。结果：该全身模拟定位扫描方案可在Eclipse v15.5中实现两套CT的重建。在工作效率上,手工重建方法生成全身模拟定位CT平均需要10 min,软件重建方法只需要5 s。两种CT重建方法在图像质量上无差异,重建CT与真实值相比误差小于1 mm。使用重建的全身模拟定位进行TBI计划设计与评估,靶区适形度指数（CI）=0.854,剂量均匀性指数（HI）=0.199。结论：本文介绍的TBI全身模拟定位CT扫描与图像重建的方法可以简单、快速地获得完整的全身模拟定位CT图像,适用于后期的TBI计划设计、优化和评估过程。     

全身皮肤电子线放疗中快速确定机架角度的方法

目的：为双机架角多野全身皮肤电子线放疗技术提供一种快速确定机架角度的方法。方法：引入一个与治疗时辐射场几何条件关联的新因子F,F与机架角度、准直器大小和源皮距相关。查阅以往相关文献,归纳总结出不同几何条件下因子F的规律,然后建立根据F快速推算机架角度的方法,再用两组试验验证该方法的有效性。结果：分析以往文献中的数据后发现,因子F的值稳定在一个固定值左右,F的平均值为0.79,标准差为0.05。新建立的快速计算方法可将机架角度搜索范围从一般方法推荐的15°缩小到5°左右。在两组试验中,最佳照射时的机架角度均能快速而准确地确定。结论：在双机架角多野全身皮肤电子线放疗技术中,因子F的引入和新的计算方法能够有效提高确定照射机架角度的效率。     

SunCHECK软件在调强放疗计划剂量验证中的应用

目的:探讨SunCHECK软件在调强放疗计划剂量验证中的应用。方法:选取新疆医科大学第一附属医院已执行IMRT计划的40例患者,应用SunCHECK软件,对所接受数据进行单独计算,然后对原始放疗计划和QA计划进行Gamma分析。最后对QA计划与ArcCHECK测量结果进行Gamma通过率比较。结果:在SunCHECK软件单独计算结果中,Monaco计划平均Gamma通过率略高于Eclipse计划。相同计划系统原始计划与QA计划Gamma通过率没有差异。使用SunCHECK软件计算QA计划（包括Monaco计划和Eclipse计划）Gamma通过率略高于ArcCHECK测量结果的Gamma通过率。结论:SunCHECK软件符合IMRT计划剂量验证需要,给放疗质控工作带来了很大的便利性。无论是作为单独放疗计划验算工具,还是以log日志文件反推进行计划验证,都应该把SunCHECK作为质量保证程序的一部分。     

全身放射治疗的剂量测量研究

目的:在全身放射治疗条件下,测量直线加速器空气中射线场均匀性,水模体内剂量分布情况,以及不同规格水模体的百分深度剂量值。方法:将加速器的源皮距(SSD)延长至450 cm,机架头旋转为90°,准直器开到最大,治疗头旋转为45°,形成菱形射野,使用剂量测量仪:PTW-UNIDOS,电离室:PTW 30001,测量Varian Clinac 2100C直线加速器的剂量值。结果与结论:加速器在空气中射线场剂量:T方向上总的平均值为5.147,绝对误差为5.8%,归一后相对误差达到;G方向上总的平均值为5.124,绝对误差为5.1%,归一后相对误差达到;此加速器的射线场均匀性可以用于全身放射治疗。水模体内剂量分布情况,在10 cm深度处,平均剂量值为8.960,归一数据中的绝对误差为;在20 cm深度处,平均剂量为6.381,从归一数据中的绝对误差为。     

Rotation Technique for Superficial Total Body Electron Beam Irradiation

Low megavoltage electrons, because of their limited penetration, have been found very useful in the treatment of generalized superficial malignancies. However, because of the complexity of the human body contour, it is extremely difficult to achieve uniform dose distribution over the entire body surface. To achieve this, various techniques ranging from two to six fields have been used. In this paper, we discuss the disadvantages of these techniques and describe a new technique, “the rotation technique,” which is superior.     

肺癌螺旋断层放疗计划设计的初步研究

目的：比较同一肺内存在上肺和下肺病灶的肺癌患者制定一个计划和单独两个计划的剂量学差异,制定出一套合理的肺癌螺旋断层放疗计划方案。方法：选择上肺和下肺病灶的10例患者,分别设计一个计划和单独两个计划,将单独两个计划的剂量学参数逻辑相加,与一个计划的剂量学参数比较,分析其差异。结果：10例患者一共48例治疗计划,所有计划均能满足合适的靶区剂量均匀度和适形度。同侧肺内病灶的患者靶区平均剂量差异在1％以内,正常肺组织V5～V15差异较大,范围为0．05％～7．47％;对侧肺内病灶的患者靶区平均剂量差异在1．5％以内,正常肺组织V,差异较大,范围为O．64％～8．36％。无论同侧肺内病灶患者和对侧肺内病灶患者,病灶间隔（PTv）大于5cm的患者,单次治疗时间均至少降低25％以上。个别患者最大降幅为50．92％。结论：对于病灶间隔（PTV）大于5cm的患者,建议分开单独设计计划,可以有效节约患者单次治疗时间,提高治疗效率,并且解决患者治疗前影像引导靶区配准的临床难题。     

Current Use of Total Body Irradiation in Haploidentical Allogeneic Hematopoietic Stem Cell Transplantation

Total body irradiation (TBI) is included in the conditioning regimen for allogeneic hematopoietic stem cell transplantation (HSCT), with unique advantages such as uniform distribution over the whole body and decreased exposure to cytotoxic chemotherapeutic agents. For individuals who lack matched sibling or matched unrelated donors, the use of haploidentical donors has been increasing despite challenges such as graft rejection and graft-versus-host disease (GVHD). Although a limited number of studies have been performed to assess the clinical role of TBI in haploidentical HSCT, TBI-based conditioning showed comparable results in terms of survival outcomes, rate of relapse, and GVHD in diverse hematologic malignancies such as leukemia, lymphoma, and multiple myeloma. Advances in supportive care, along with recent technical improvements such as restriction of maximum tolerated dose, appropriate fractionation, and organ shielding, help to overcome diverse adverse events related to TBI. Post-transplantation cyclophosphamide was used in most studies to reduce the risk of GVHD. Additionally, it was found that post-transplantation rituximab may improve outcomes in TBI-based haploidentical HSCT, especially in patients with B-cell lymphoma. Along with the advances of techniques and strategies, the expansion of age restriction would be another important issue for TBI-based haploidentical HSCT considering the current tendency toward increasing age limitation and lack of matched donors. This review article summarizes the current use and future perspectives of TBI in haploidentical HSCT.     

Comparison of High Doses of Total Body Irradiation in Myeloablative Conditioning before Hematopoietic Cell Transplantation

Malignancy relapse is the most common cause of treatment failure among recipients of hematopoietic cell transplantation (HCT). Conditioning dose intensity can reduce disease relapse but is offset by toxicities. Improvements in radiotherapy techniques and supportive care may translate to better outcomes with higher irradiation doses in the modern era. This study compares outcomes of recipients of increasing doses of high-dose total body irradiation (TBI) divided into intermediate high dose (IH; 13-13.75 Gy) and high dose (HD; 14 Gy) with standard dose (SD; 12 Gy) with cyclophosphamide. A total of 2721 patients ages 18 to 60 years with hematologic malignancies receiving HCT from 2001 to 2013 were included. Cumulative incidences of nonrelapse mortality (NRM) at 5 years were 28% (95% confidence interval [CI], 25% to 30%), 32% (95% CI, 29% to 36%), and 34% (95% CI, 28% to 39%) for SD, IH, and HD, respectively (P = .02). Patients receiving IH-TBI had a 25% higher risk of NRM compared with those receiving SD-TBI (12 Gy) (P = .007). Corresponding cumulative incidences of relapse were 36% (95% CI, 34% to 38%), 32% (95% CI, 29% to 36%), and 26% (95% CI, 21% to 31%; P = .001). Hazard ratios for mortality compared with SD were 1.06 (95% CI, .94 to 1.19; P = .36) for IH and .89 (95% CI, .76 to 1.05; P = .17) for HD. The study demonstrates that despite improvements in supportive care, myeloablative conditioning using higher doses of TBI (with cyclophosphamide) leads to worse NRM and offers no survival benefit over SD, despite reducing disease relapse.     

A Phase 1 Trial of Eltrombopag in Patients Undergoing Stem Cell Transplantation after Total Body Irradiation

Stem cell transplantation can be associated with significant periods of thrombocytopenia, necessitating platelet transfusions and contributing to the risk of bleeding. Thrombopoietin receptor agonists have been shown to enhance platelet counts in other clinical settings, and so a phase 1 clinical trial was conducted to assess the safety, pharmacokinetics, and maximum tolerated dose of once-daily eltrombopag in patients undergoing stem cell transplantation with conditioning regimens containing total body irradiation ≥400 cGy. Eltrombopag was examined at dosage levels of 75, 150, 225, and 300 mg given orally once daily for 27 days, starting at 24 to 48 hours post-transplantation. Pharmacokinetic sampling was performed over a 24-hour period after the first dose of eltrombopag, as well as during the second week of treatment (steady-state). Nineteen patients were enrolled, 15 of whom completed protocol treatments. Three patients completed each dose level up to 225 mg, and 6 completed treatment at the highest dose of 300 mg. Four patients were replaced because drug compliance was <75% of planned doses. No dose-limiting toxicities were observed in this heterogeneous post-transplantation patient population. Common adverse events were related to standard stem cell transplantation. One episode of pulmonary embolus occurred 9 days after discontinuation of eltrombopag, and the only other thromboembolic episode was a grade 2 catheter-related clot. We conclude that up to 27 days of once-daily dosing of eltrombopag after stem cell transplantation is well tolerated.