全身照射的剂量学方法

全身照射是治疗白血病和晚期实体瘤的一个重要组成部分，然后而于各放疗中心的设备状况、射线的能量、射野大小及治疗室的大小各不相同，从而使各放疗中心所采用的物理照射技术也不相同。因此，对比各种不同物理照射技术及临床结果，对于确定最佳放射治疗计划就显得非常重要。本从照射体位及射野均匀性、济量计算、处方计算及分次照射、肺铅档等四个方面讲述全身照射的剂量学方法，这个问题也是放疗医生、特别是放射物理人员在实施全身照射以前必须解决的问题。     

浅谈放疗患者治疗过程中的皮肤护理

放射性治疗是利用放射线来抑制和杀灭瘤细胞而达到治疗的目的。放射线照射在病人体表的大小范围称之为射野。在医院里，放疗医生根据肿瘤的范围及生物学要求精心设计病人的射野，用紫墨水在病人皮肤上画出。在每次照射治疗时，医生都要看清病人的射野，才能给予正确的照射。因此要求病人一定要注意保护射野使其保持清晰状态。再就是皮肤的完好无损在照射治疗中也是至关重要的。     

29例白血病骨髓移植的全身照射治疗

白血病患者在骨髓移植前一般都做大剂量的化疗和全身照射（ＴＢＩ）治疗，以求达到根治或长期缓解的目的。ＴＢＩ与常规放疗相比在照射方法及剂量学方面有着很大的不同。我院自１９９０年开始了这一技术的临床应用研究，至１９９６年１２月已治疗２９例，取得较好疗效。１　材料和方法１．１　技术的前期准备１．１．１　设计制作专用治疗床全身照射要求在一个射野内包罗病人的全部身躯，我们使用的ＶａｒｉａｎＣＬ１８００型直线加速器在常规治疗位１００ｃｍ处最大射野是４０ｃｍ×４０ｃｍ，为此我们设计一专用治疗床，将治疗位延至３８…     

应用EPID对放射治疗摆位误差的研究

放射治疗中对照射野位置的验证是放疗质量保证的重要内容.2000-2004年我科应用Varian电子射野影像系统（EPID）对头颈部、乳腺、胸腔内以及盆腔肿瘤的照射野进行了动态的射野验证和修正.     

调节灯光野与照射野符合性的简便方法

调节灯光野与照射野符合性的简便方法缪旭东鞠永健在肿瘤放射治疗中，物理技术的质量保证（ＱＡ）和质量控制（ＱＣ）问题尤为重要，其中照射野特性检查中的灯光野与射野的符合性是放射治疗物理技术质量保证的一项重要内容。对于灯光野和射野的符合性国内外均有较为严格的...     

肿瘤病人放射治疗的一次全身等效剂量

在抗放药物临床过渡中,常选择某些肿瘤放疗病人进行研究,如食道癌、宫颈癌和乳腺癌等。其照射条件与通常放射生物实验的动物照射有以下两点不同:(1)长时间的多次照射;(2)小射野局部照射。在这种放疗条件下,射线对病人全身引起多大的损伤,即一次全身等效剂量多大,这是药物过渡工作十分关心的问题之一。关于多次照射归一到一次照射剂量方法,文献报导很多。     

对全身照射的进一步分析

全身照射时相当小的剂量差别就可引起生物学效应很大的不同,但目前世界上开展全身照射的各中心之间所采用的每分割剂量、分割方式、总剂量都不相同,以至于各自的结果无法互相比较。各中心对全身照射研究的终点也不同,包括急性副作用、免疫抑制作用、灭癌效应及远期副作用。作者认为应将近期副作用及灭癌作用作为研究的终点。放疗医师应发挥其在小野照射方面的特长,每次3～4 Gy,3～4次的全身照射认为是最好的方法。     

X射线1/4照射野的输出剂量计算及剂量测量验证

新型的直线加速器中均配有独立准直器 ,在某些临床治疗中 ,需要用到非对称射野来削弱线束扩展的影响 ,以减少对正常组织的照射剂量。有时为了相邻野的衔接 ,避免组织中剂量冷热点的出现 ,也要用到独立准直器功能。对于常规不对称射野处方剂量的计算许多文献均有论述[1 3 ] ,某些病例如乳腺癌病人等需用到的双不对称射野 ,Ｘ轴切线照射避免正常肺受量 ,Ｙ轴切线照射能使得与锁骨上野有良好衔接。笔者分析了这一类双不对称射野 (简称 1 4照射野 )的剂量计算 ,并对结果进行实测验证 ,现报道如下。一、材料和方法1 使用的仪器设备 :西门子Ｍｅ…     

一种侧卧位X射线分次全身照射技术及剂量监测结果分析

目的 报道一种侧卧位前后对穿X射线分次全身照射技术,并对照射中的实时剂量监测结果进行分析。方法 采用Varian Trilogy医用电子直线加速器10 MV X射线,行水平野对穿全身照射,源到模体表面距离390 cm,测量X射线全身照射条件下的射野百分深度剂量、离轴剂量分布及绝对剂量输出。对10例患者采用侧卧位前后对穿野分次全身照射。照射处方剂量1200 cGy/6次,共3 d,体中线剂量率约5.0 cGy/min。治疗时利用多通道半导体剂量计实时监测患者剂量准确性及剂量分布均匀性,采用固体水进行剂量非均匀性补偿。结果 治疗条件下模体测量射野离轴剂量分布均匀性<±5.0%,最大剂量点处绝对剂量输出为0.0721 cGy/MU。10例患者均能够顺利完成侧卧位治疗,各个部位监测总剂量偏离处方剂量-4.9%~6.7%,平均监测剂量均匀性<5.0%。结论 侧卧位X射线全身分次照射技术患者耐受性好,照射过程中实时监测剂量,采用固体水进行剂量非均匀性补偿,能够保证患者接受准确均匀的剂量分布,方法简便易行。     

个人剂量监测工作改进的建议

早期乳腺癌的术后放疗采用乳腺定位板、等中心 (ＳＡＤ)摆位技术、非对称半野照射以及三维治疗计划系统的优化等技术对早期乳腺癌行术后切线放疗已成定式 ,特别是非对称半野照射技术已被某些放疗中心所采用 ,它能有效地降低肺部受照射剂量 ,但是其对肺部剂量的改善程度尚少见报道[1 ,2 ] 。笔者通过比较三维治疗计划系统给出的体积剂量直方图 ,对对称野和非对称半野照射在乳腺癌切线照射时肺受照射体积进行量化比较和分析。一、材料和方法1 体位及射野 :患者仰卧在平床上 ,手臂上举并握住乳腺定位棒。切线照射野的宽度应以包括全部乳腺组织…     

Clinical application of GAFCHROMIC EBT film for in vivo dose measurements of total body irradiation radiotherapy.

The GAFCHROMIC EBT film model is a fairly new film product designed for absorbed dose measurements of high-energy photon beams. In vivo dosimetry for total body irradiation (TBI) remains a challenging task due to the extended source-to-surface distance (SSD), low dose rates, and the use of beam spoilers. EBT film samples were used for dose measurements on an anthropomorphic phantom using a TBI setup. Additionally, in vivo measurements were obtained for two TBI patients. Phantom results verified the suitability of the EBT film for TBI treatment in terms of accuracy, reproducibility, and dose linearity. Doses measured were compared to conventional dosimeter measurements using thermoluminescent dosimeters (TLDs), resulting in an agreement of 4.1% and 6.7% for the phantom and patient measurements, respectively. Results obtained from the phantom and patients confirm that GAFCHROMIC EBT films are a suitable alternative to TLDs as an in vivo dosimeter in TBI radiotherapy.     

TBI treatment planning using the ADAC Pinnacle Treatment Planning System

The use of total-body irradiation (TBI) for the purpose of bone marrow transplant is an established procedure at many institutions. In our institution, the TBI monitor unit (MU) calculation starts with the calibration done at the same conditions of the treatment source-axis distance (SAD) = 350 cm for the field size of 40 × 40 cm at a depth of 10 cm). The dose rate in the central axis of the beam at this distance is measured in cGy/MU. A tissue phantom ratio table obtained in the condition of treatment together with off-axis factors is used in the MU calculation for each particular patient. The treatment is done with the patient lying on his/her back and the beam is delivered using right-to-left lateral beams. Due to different thickness’ of the patient, a lead compensator is built to compensate for the different parts of the body. Eighteen or 10-MV x-ray photons are used in the TBI treatment, and a 1-cm-thick lucite plate is placed near the patient to increase the dose to the surface. In vivo dosimetry using diodes is done to verify the calculations. The Rando-Phantom™ was computed-tomography scanned from the head to the abdomen with 1-cm-thick slices covering 70 cm of the phantom. This simulated the TBI treatment and correlated the calculations done by the ADAC treatment planning system to film measurements at the pelvis and lung levels. These results agreed within 5% of the measured dose. The use of the upper arms to reduce the dose to the lungs and optimization of dose using special compensators has been studied using the treatment planning system. Use of the multileaf collimator to compensate the dose received by the patient has been explored in this paper.     

Total body irradiation in Essen--dosimetry and physical treatment planning

Since 1975, in Essen 109 patients received total body irradiation (TBI) prior to bone marrow transplantation. About 80 patients were treated by bilateral 5.7 MeV photon beams. Three new TBI techniques were developed providing precise, homogeneous, reliable and reasonable a. p./p. a. TBI for adults and children. Systematic TBI dosimetry and the beam-zone method enable for individual treatment planning.     

Vulnerability of folate in plasma and bone marrow to total body irradiation in mice

PURPOSE: To examine how folate status in a body is influenced by oxidative stress. MATERIAL AND METHODS: Mice were given total body irradiation (TBI) by X-ray, and changes in the concentration of folate were compared to those in vitamins C and E. RESULTS: In a time-dependent study, folate in plasma and bone marrow decreased from 5 h until 120 h post-TBI at 3 Gy. Folate in plasma and bone marrow decreased in a dose-dependent manner at 24 h. Marked decreases of vitamins C and E were also detected in bone marrow, but not in plasma even at 10 Gy of TBI. The susceptibility of plasma folate by irradiation was confirmed by an in vitro exposure study. Neither vitamins C and E nor folate were decreased in the liver by TBI. CONCLUSION: It is suggested that folate is vulnerable to oxidative stress, and folate may need to be evaluated, particularly for TBI or radiotherapy.     

Optimization of a dosimetric procedure in total body irradiation

The experimental dosimetry of 2 radiotherapy beams produced by a 60Co Picker unit and by a Siemens 4 MV unit, respectively, was analyzed to verify the use of tissue air ratio (TAR) and tissue maximum ratio (TMR) in the computerized planning of total body irradiation (TBI). The use of a small ionization chamber PRO5P Capintec in anthropometric phantoms allowed us to test a computed calculation procedure adopted to reduce both experimental uncertainties and time consumption. The experimental test on the computed procedure was also useful to identify the equivalent fields the patient's body had to be divided into for dosimetric planning. Such dosimetric specifications as average dose to the patient and degree of dose inhomogeneity are calculated when the thickness of compensator filters in perspex is optimized. Following the guidelines reported in ICRU 29, a dosimetric record is presented. In page 1 the target volume is described, in page 2 the provisional treatment planning, and in page 3 the actual treatment planning, checked with in vivo TLD measurements, and the dose specifications for TBI.     

全身照射后肠黏膜通透性与肠三叶因子mRNA表达的关系

目的 探讨全身照射(TBI)对肠道黏膜通透性和肠三叶因子(ITF)mRNA表达的影响以及二者之间的关系.方法 32只BALB/c小鼠随机均分为4组:空白对照组和总剂量8.0 Gy全身照射后4、8和12 d组.TBI剂量8.0 Gy,剂量率1.0 Gy/min.高效液相色谱-蒸发光散射检测器分析(HPLC-ELSD)检测尿液标本中乳果糖与甘露醇的排出率比值(L/M),评价各组小鼠的肠道通透性;收集空肠组织标本,实时荧光定量PCR检测肠道ITF mRNA表达水平.结果 TBI后4、8和12d组L/M比值分别为0.5092±0.0353,0.7174±0.0116和0.7295±0.0063,均明显高于空白对照组(0.2908±0.0533,F=321.47,P＜0.05).TBI后4、8和12 d组ITF mRNA表达水平分别为0.78612±0.1428,0.2521±0.1223,和0.2306±0.0221,均显著低于空白对照组(1.3498±0.0476,F=235.71,P＜0.05).各TBI组中L/M与肠道ITF mRNA水平呈显著负相关(r=-0.985,P＜0.01).结论 TBI后随着时间延长ITF mRNA表达逐渐下降而肠黏膜通透性逐渐增加,即TBI后ITF mRNA表达与肠道通透性呈显著负相关.ITF在TBI所致肠道黏膜通透性增加中起着保护作用.

Abstract：

Objective To investigate the change of the intestinal permeability,the expression level of intestinal trefoil factor (ITF) mRNA and the relationship between them after total body irradiation (TBI),and explore the effect of TBI on the development of intestinal permeability and the expression level of ITF mRNA.Methods Twenty two BALB/c mice were randomly divided into 4 equal groups: 3 groups at 4,8 and 12 d after TBI with the total dose of 8.0 Gy and the dose rate of 1.0 Gy/min respectively,and a control group.Lactulose (L) and mannitol (M) were perfused into the esophagus before the experiment and urine samples were collected.Liquid chromatography was used to measure the L/M excretion ratio in the urine samples collected 4,8,and 12 days after the TBI.And then the mice were killed with their intestine were taken out.The expression of ITF mRNA in the jejunum tissue was detected by real-time fluorescence quantitative PCR.Results The urine L/M ratio levels of the groups 4,8 and 12 days after TBI were (0.5092 ± 0.0352),(0.7174 ± 0.0116),and (0.7295 ± 0.0533) respectively,all significantly higher than that of the control group [(0.2908 ± 0.0533),F = 321.47,P ＜ 0.05].The ITF mRNA expression levels of groups 4,8 and 12 days after TBI were (0.78612 ±0.1428),(0.2521 ±0.1223),and (0.2306 + 0.0221 ) respectively,all significantly lower than that of the control group [( 1.3498 + 0.0476),F = 235.71 ,P ＜ 0.05].The urine L/M ratio was significantly negatively correlated with the expression of ITF mRNA in all TBI groups (r = - 0.985,P ＜ 0.01 ).Conclusions The intestinal permeability increases and the expression level of ITF mRNA decreases after TBI.The urine L/M ratio is negatively correlated with the expression level of ITF mRNA after TBI.ITF is involved in protection against intestinal permeability induced by TBI.