450例全身照射患者的照射方法及结果分析

目的 探讨450例全身照射(TBI)患者的照射方法及结果.方法 (1)测算方法:①对TLD的剂量标定采用单点剂量标定法;②人体纵轴方向体中线吸收剂量的测算采用对皮肤表面入射与出射剂量的平均值并加修正的方法.(2)照射方法:①4个野照射方法:射线成水平入射,射野的对角线与患者人体长轴方向一致,患者取仰、侧卧位,组成两对平行对穿的照射野.照射方案采用患者在TBI前一周左右通过4个野等剂量预照射(预照剂量为TBI总量的1/10),筛选出均匀度最佳的仰、侧卧位相同或不同的剂量配比方案,用于TBI的正式照射.②小野照射方法:患者仰坐在特制木椅上,照射分左侧位和右侧位两野平行对穿照射.椅背可顺时针(CW)或反时针(CCW)旋转,脚蹬可前后移动并可固定.③双侧位照射方法:与4个野照射方法基本相同,但患者仅取仰卧位,射线分别从身体两侧入射形成一对平行对穿的照射野.在使用双侧位照射方法收治的患者中,有5例患者采用了FFBI治疗方案.另外,收治的全部TBI患者,在射线入射方向上,紧贴患者身体均放置一块具有一定建成厚度的有机玻璃散射屏.结果 ①使用4个野照射方法的87例患者,其人体纵轴方向体中线的不均匀度平均为±8.1%.②使用小野照射方法收治的91例患者,其不均匀度平均为±7.4%.⑧使用双侧位照射方法收治的272例患者,其不均匀度平均为±4.9%.结论 ①使用TLD或半导体剂量仪实时监测患者体表入射与出射剂量是TBI治疗重要的质量控制和保证.②对使用常规仰、侧卧位,射野不能完全包罗患者身体各个部位时,采用小野照射方法,它从过程到结果都优于4个野照射技术.③当射野的对角线＜110 em时,采用4个野和小野照射的均匀度都不及对角线＞180 cm患者取平卧的双侧位照射.④双侧位与前后野照射比较,各有特点.实际上后者更适合于使用PTBI治疗亭,患者取半坐立姿,分前后野接受多次TBI照射.⑤STBI虽不具有FTBI放射生物学的优势,但从某种意义上讲,它也是TBI的一种较为实用的形式.     

优化全身照射技术对造血干细胞移植后发生间质性肺炎影响的初步观察

目的:探讨优化医用直线加速器高能X线全身照射(total body irradiation, TBI)的技术对造血干细胞移植后发生间质性肺炎(IP)的影响.方法:28例患者接受以环磷酰胺(CY) 全身放疗±依托泊苷(Vp-16)为预处理方案的造血干细胞移植,TBI采用分割放疗、肺挡铅技术,其中19例患者采用热释光剂量片(TLD)监测全身放疗的肺吸收剂量,TBI总量12Gy,共6次,肺部剂量8.5Gy.结果:28例患者随访24～104个月,中位随访时间75个月,5年总生存率(OS)为(53.6±9.4)%,5年无复发生存(RFS)(71.1±8.6)%;19例接受热释光剂量片监测吸收剂量的患者,肺吸收中位剂量8.44Gy,脐部吸收中住剂量11.87Gy,全身剂量的不均匀性<±10%;28例患者无1例发生IP.结论:采用分割全身放疗、肺挡铅、并用热释光剂量片监测肺吸收剂量可降低IP的发生.     

全身皮肤电子线照射技术的开发及研究——台湾经验交流

目的 开发设计躺姿及旋转板电子线全身皮肤肿瘤照射新技术,可使患者从头至脚全身都给到足够且均匀剂量照射。方法 躺姿及旋转板电子线照射时直线加速器机头水平往上或水平往下照射,可合成一个可用的剂量剖面野的旋转角度,再求出绝对剂量及PDD跟加成因子后就可让患者得到足够且均匀的电子剂量以便做全身性电子线治疗。结果 躺姿及旋转板全身电子线照射方式结果显示,采取任一姿式做照射都可在患者治疗表面行成一个平坦的剂量剖面,此剖面剂量均匀度可控制在 ±10%的范围内。结论 躺姿及旋转板电子线照射方式可同时从头至脚在同一次治疗,并得到和全身其余区域相同且均匀的剂量。     

造血干细胞移植前全身照射的毒副反应及影响因素分析

目的　观察和分析造血干细胞移植前采用全身照射治疗所产生的近期和晚期毒副反应。方法　自１９９９年５月至２００５年１２月,我科对３１２例造血干细胞移植患者进行了全身照射。采用６０Ｃｏγ射线照射,患者取侧卧体位,腹脐处中心平面剂量率控制在４～６ｃＧｙ／ｍｉｎ,平均（５.２±１.１３）ｃＧｙ／ｍｉｎ,总剂量７～１２Ｇｙ,分１～３次照射,每天照射１次,照射期间制作个体化的肺挡铅进行肺屏蔽。结果　在全身照射后,患者近期出现了Ⅰ ～Ⅱ级的发热、胃肠道反应、口腔炎及出血性膀胱炎,均可耐受,无需特殊处理。间质性肺炎发生率为９.９％,造血系统重建和干细胞植活率达７０％以上,患者均未出现严重的肾功能衰竭。结论　采用剂量率５ｃＧｙ／ｍｉｎ照射,总照射剂量控制在７～１２Ｇｙ,肺中位剂量不超过７.５Ｇｙ,１次／天,共照射１～３次的剂量分割模式,是有效和安全的造血干细胞移植预处理方案。     

单次与分次全身照射对干细胞移植患者肾功能损伤及其影响因素分析

目的:探讨造血干细胞移植前全身单次和分次照射对移植患者肾功能的损伤及其影响因素。方法:回顾性分析2001-2010年我院以全身放射(TBI)为基础方案预处理后73例造血干细胞移植患者的临床资料。根据TBI方案不同,分为单次照射组(A组,8 Gy)、分次照射组(B组,12 Gy分6次照射)。根据血清肌酐水平分别评估肾小球滤过率(eGFR)的基线水平及TBI后1、4、12、18和24个月的eGFR变化,肾功能损伤定义为eGFR较基线水平下降≥30%,采用t检验及Kaplan-meier方法对病例随访资料进行肾存活生存曲线分析,比较两种TBI方式对肾功能的损伤。采用逐步逻辑回归方法分析年龄、TBI剂量率、环孢素以及移植物抗宿主病(GvHD)等因素对肾功能损伤的影响。结果:TBI后1和4个月时A组肾损伤的发生率分别为12.20%和34.15%,B组分别为9.37%和21.88%;且肾损伤程度〔(各观察时间点eGFR-基线水平eGFR)/基线水平eGFR〕A组大于B组,4个月时A组为-0.25±0.20,B组-0.14±0.18,差异有统计学意义,P<0.05。12、18和24个月时A组慢性肾损伤的发生率分别为34.15%、48.78%和48.78%,B组分别为28.13%、43.75%和46.88%,A组肾损伤的发生率高于B组,但两组患者各时间点的肾损伤程度差异无统计学意义,P>0.05。Kaplan-meier肾存活生存曲线显示,两组的肾存活函数均趋于下降,但B组肾存活率高于A组。逐步逻辑回归模型分析显示,干细胞移植后肾功能的损伤与年龄密切相关,而与照射剂量、环孢素应用及GvHD无关。结论:单次及分次全身照射均能够造成造血干细胞移植患者的急、慢性肾损伤,但单次照射的早期肾损伤较为明显,分次照射对肾功能的远期影响更小。年龄与干细胞移植患者的肾损伤密切相关。     

全身皮肤电子束照射剂量学参数的测量和讨论

目的对全身皮肤电子束照射(TSEI)的剂量学参数进行测量并讨论。方法采用双机架角多野照射技术，在源皮距等于380cm下对6、8MeV电子束相关照射野的剂量学参数进行测量。采用平行板电离室和半导体探头测量百分深度量；用半导体探头测量均匀模体内某一深度处各点剂量均匀性，用剂量胶片测量人体体模横截面的剂量分布。结果对于6、8MeV电子束双机架角6个野照射，最大剂量深度都在0～3mm处，6MeV的80％，50％剂量深度分别在7、14mm处，8MeV的80％、50％剂量深度分别在7、17mm处。在机架旋转方向上模体2、11mm深度处野内各测量点的剂量均匀性在-10％～ 3％内。得出了人体模脐部横断面内等剂量分布曲线。结论全身皮肤电子束照射的剂量学参数与常规单野照射的剂量学参数有较大区别，临床治疗前需要准备充分的临床剂量学资料。     

用MOSFET探测器进行乳腺癌放疗剂量的实时检测

目的 研究用金属氧化物半导体场效应晶体管(MOSFET)探测器测量接受高能X射线半束照射的乳腺癌患者的照射剂量。方法 采用MOSFET探测器首先在人体模型上测量,研究在6MV X射线半束照射中相邻半野剂量的分布情况和加速器相关因子的影响,然后实时测量10例乳腺癌患者腋锁野与胸壁切线野6MVX射线半束照射时匹配线上、腋锁...     

造血干细胞移植前全身照射急性放射性反应与照射剂量的关系

目的探讨造血干细胞移植前全身照射急性放射性反应与照射不同总剂量及分次剂量的关系。方法回顾性分析2015年5月至2019年12月于石家庄平安医院造血干细胞移植前接受6 MV X线全身照射预处理的48例患者的临床资料。将患者按照射总剂量分为8 Gy组(12例)、10 Gy组(31例)和12 Gy组(5例),按分次照射剂量分为4 Gy/次组(17例)和5 Gy/次组(31例),总结比较各组患者放疗后的口腔黏膜、咽部、涎腺、上消化道、下消化道及肺的急性放射性反应发生情况。结果照射总剂量8 Gy组咽部急性放射性反应0级11例(91.7%),1级1例(8.3%);10 Gy组0级10例(32.3%),1级13例(41.9%),2级4例(12.9%),3级3例(9.7%),4级1例(3.2%);12 Gy组0级2例(40.0%),1级、2级、3级各1例(20.0%);照射总剂量8 Gy组咽部急性放射性反应较10 Gy组和12 Gy组轻,差异有统计学意义(χ2=11.338,P=0.003);其他部位急性放射性反应发生率差异均无统计学意义(均P>0.05)。分次照射剂量4 Gy/次组咽部急性放射性反应0级13例(76.5%),1级2例(11.8%),2级、3级各1例(5.9%);5 Gy/次组0级10例(32.3%),1级13例(41.9%),2级4例(12.9%),3级3例(9.7%),4级1例(3.2%);分次照射剂量4 Gy/次组咽部急性放射性反应较5 Gy/次组轻,差异有统计学意义(Z=-2.606,P=0.009);其他部位急性放射性反应发生率差异均无统计学意义(均P>0.05)。结论造血干细胞移植前全身照射总剂量8 Gy及分次剂量4 Gy/次能减轻咽部急性放射性反应。     

含全身照射方案的造血干细胞移植对难治性白血病的疗效

目的探讨含全身照射(TBI)预处理方案的造血干细胞移植(allo-HSCT)对难治性白血病的疗效和安全性。方法采用含TBI预处理方案的allo-HSCT治疗20例难治性白血病患者,采用骨髓加外周血干细胞联合移植,预处理方案包括阿糖胞苷、氟达拉滨及TBI等,全身照射采用6MV-X照射,移植物抗宿主病(GVHD)预防采用经典环孢菌素A(CSA)和氨甲蝶呤(MTX)及抗胸腺细胞免疫球蛋白(ATG)、CD25单克隆抗体,移植后观察并发症和患者无病生存等情况。结果 20例患者均获造血重建,植入证据检测证实100%为完全供者造血。TBI后患者有轻度恶心、呕吐、腮腺肿胀等症状,无1例发生间质性肺炎。中位随访时间为12.5个月(6～36个月),共8例发生GVHD,死亡2例;因感染死亡2例、复发死亡6例,其余10例患者仍无病生存,2年无病生存率为50%。结论含全身照射方案的造血干细胞移植,对难治性白血病是1种安全有效的治疗方案,可作为挽救治疗的关键技术。广泛应用于临床。     

电子照射野影像装置在剂量验证方面的研究进展

电子照射野影像装置 (ｅｌｅｃｔｒｏｎｉｃｐｏｒｔａｌｉｍａｇｅｄｅｖｉｃｅ,ＥＰＩＤ)作为一种新的放射治疗辅助装置 ,目前主要用于患者治疗前或治疗过程中的位置验证 ,通过对照射野影像与模拟定位片或治疗计划系统产生的数字重建影像进行比较 ,验证患者摆位时照射野设置的几何精度。随着调强适形放射治疗在临床中的应用 ,逆向治疗计划产生的调强照射野强度分布和患者体内剂量分布的验证 ,以及治疗过程中剂量的实时监测变得极为重要。目前 ,用于实现这一目的的方法主要有胶片测量、半导体测量和热释光测量等 ,这些方法都有其缺点 ,不能…     

Toxicity and dosimetry of fractionated total body irradiation prior to allogeneic bone marrow transplantation using a straightforward radiotherapy technique

Since 1989, we have used a relatively straightforward technique for giving total body irradiation (TBI), using anterior and posterior parallel opposed fields with the arms and fists acting as compensators. The dosimetry, toxicity and outcome of 48 patients (26 adults, 22 children) treated with TBI using this technique have been audited. A dose of 14.4 Gy in eight fractions over 4 days was prescribed to all patients with an unrelated donor and 12 Gy in six fractions over 3 days to those with a sibling donor. From May 1994, all children received 14.4 Gy because of a recommendation from the United Kingdom Children's Cancer Study Group. The range of lung dosimetry was −6% to +7% when the dose was specified to the lung maximum. The trunk doses were all within ±10% of the prescribed dose. Doses to other regions of the body were less homogeneous but clinically acceptable in that the minimum doses were never less than −10% of the prescribed dose. Mucositis was the most common side effect; its treatment with opioids was more frequent after 14.4 Gy than after 12 Gy (P = 0.0004) and in adults than in children (P = 0.01). No cataracts have yet been seen in these patients. The radiation was not found to be a proven cause of clinical pneumonitis, although there was one death due to interstitial pneumonitis, which was likely to have been caused by cytomegalovirus infection in which radiation pneumonitis could not be excluded. There were no other suspected TBI-related deaths.In conclusion, this straightforward technique achieved acceptable dosimetry and was well tolerated.     

Total body irradiation for treatment of haematological diseases

The present status of total body irradiation (TBI) as a part of the treatment of haematological diseases was discussed during a separate symposium at the 5th Annual ESTRO meeting at Baden-Baden. The experimental techniques applied in Europe, the dosimetry for TBI, the radiobiological aspects and the late effects after TBI have been reviewed. For specific geometries, precautions have to be taken to avoid increased dose contributions at the skin due to electrons scattered from the wall behind the patient. CT data can be useful for the individualization of the exposure regimen of patients with extreme variations in lung anatomy or lung density. An appreciable number of centres apply in vivo dosimetry, however, special care is needed for the correct interpretation of the dosimeter readings. A number of late effects, including induction of cataract and secondary tumours has been observed after TBI. The techniques applied for TBI at the various centres and the temporal administration of the dose show wide variations. At present, the patient material is too heterogeneous to draw any conclusion about an optimum schedule for a TBI regimen. Further cooperation between clinicians, radiobiologists and radiation physicists has to be established to achieve consistency and further improvement of the results after TBI.     

‘Boomerang’ technique: An improved method for conformal treatment of locally advanced nasopharyngeal cancer

The primary aim of the present study was to assess radiation dosimetry and subsequent clinical outcomes in patients with locally advanced nasopharyngeal cancer using a novel radiation technique termed the ‘Boomerang’. Dosimetric comparisons were made with both conventional and intensity modulated radiation therapy (IMRT) techniques. This is a study of 22 patients treated with this technique from June 1995 to October 1998. The technique used entailed delivery of 36 Gy in 18 fractions via parallel opposed fields, then 24 Gy in 12 fractions via asymmetric rotating arc fields for a total of 60 Gy in 30 fractions. Patients also received induction and concurrent chemotherapy. The radiation dosimetry was excellent. Dose?volume histograms showed that with the arc fields, 90% of the planning target volume received 94% of the prescribed dose. Relative to other conventional radiation therapy off‐cord techniques, the Boomerang technique results in a 27% greater proportion of the prescribed dose being received by 90% of the planning target volume. This translates into an overall 10% greater dose received for the same prescribed dose. At 3 years, the actuarial loco‐regional control rate, the failure‐free survival rate and the overall survival rate were 91, 75 and 91%, respectively. At 5 years, the actuarial loco‐regional control rate, the failure‐free survival rate and the overall survival rate were 74, 62 and 71%, respectively. The Boomerang technique provided excellent radiation dosimetry with correspondingly good loco‐regional control rates (in conjunction with chemotherapy) and very acceptable acute and late toxicity profiles. Because treatment can be delivered with conventional standard treatment planning and delivery systems, it is a validated treatment option for centres that do not have the capability or capacity for IMRT. A derivative of the Boomerang technique, excluding the parallel opposed component, is now our standard for patients with locally advanced nasopharyngeal cancer when IMRT is not available.     

Two-dimensional mapping of underdosed areas using radiochromic film for patients undergoing total skin electron beam radiotherapy

PURPOSE: To demonstrate the viability of radiochromic film as an in vivo, two-dimensional dosimeter for the measurement of underdosed areas in patients undergoing total skin electron beam (TSEB) radiotherapy. The results were compared with thermoluminescent dosimeter measurements. METHODS AND MATERIALS: Dosimetry results are reported for an inframammary fold of 2 patients treated using a modified version of the Stanford six-position (i.e., six-field and dual-beam) TSEB technique. The results are presented as contour plots of film optical density and percentage of dose. A linear dose profile measured from film was compared with the thermoluminescent dosimeter measurements. RESULTS: The results showed that the percentage doses as measured by film are in good agreement with those measured by the thermoluminescent dosimeters. The isodose contour plots provided by film can be used as a two-dimensional dose map for a patient when determining the size of the supplemental patch fields. CONCLUSION: Radiochromic film is a viable dosimetry tool that the radiation oncologist can use to understand the surface dose heterogeneity better across complex concave regions of skin to help establish more appropriate margins to patch underdosed areas. Film could be used for patients undergoing TSEB for disorders such as mycosis fungoides or undergoing TSEB or regional skin electron beam for widespread skin metastases from breast cancer and other malignancies.     

External radiation therapy boost to the vaginal vault: feasibility of intracavitary dosimetry using a commercial diode system

PURPOSE: An overall check of the whole dosimetry procedure by intracavitary in vivo dosimetry, using n-type silicon diode dosimeter, was performed during 6-MV x-ray irradiation of the vaginal vault. The dose delivered to the isocenter by all treatment fields was evaluated. METHODS AND MATERIALS: The diode dosimeter was calibrated against an ion chamber and tissue maximum ratio, field size factor, SSD factor, and temperature dependence studies were performed. Diode system accuracy, linearity, and reproducibility were also tested. Patients' dose data were collected and comparision was made with respect to treatment-planning dose calculations. Ten patients with cervical cancer and endometrial cancer were treated with surgery and irradiation. During the boost to the vaginal vault, a diode was inserted by an intravaginal device and the vaginal vault was the isocenter of the four fields. The field size generally was not larger than 10 x 10 cm2. RESULTS: Diode-measured "tissue maximum ratio" agreed to within 1% with those measured with an ion chamber in field from 7 x 7 to 10 x 10 cm2. The diode also exhibited a temperature dependence of 0.1% degrees C(-1). For 10 patients treated with a 6-MV beam, the agreement with treatment-planning dose calculations was shown to be better than +/-4%. CONCLUSION: The good accuracy and reproducibility of the diode system shows that determination of the dose at isocenter, for patients treated in the pelvic region, can be performed with n-type diodes accurately. On the other hand, in the vaginal vault boost, external-beam radiotherapy is delivered accurately and in vivo dosimetry is really not indicated.     

In-vivo dosimetry by diode semiconductors in combination with portal films during TBI: reporting a 5-year clinical experience.

BACKGROUND AND PURPOSE: In-vivo dosimetry is vital to assure an accurate delivery of total body irradiation (TBI). In-vivo lung dosimetry is strongly recommended because of the risk of radiation-induced interstitial pneumonia (IP). Here we report on our 5-year experience with in-vivo dosimetry using diodes in combination with portal films and assessing the effectiveness of in-vivo dosimetry in improving the accuracy of the treatment. Moreover, we wished to investigate in detail the possibility of in-vivo portal dosimetry to yield individual information on the lung dose and to evaluate the impact of CT planning on the correspondence between stated and in-vivo measured doses. MATERIALS AND METHODS: From March 1994 to March 1999, 229 supine-positioned patients were treated at our Institute with TBI, using a 6 MV X-rays opposed lateral beam technique. 146 patients received 10 Gy given in three fractions, once a day (FTBI), shielding the lungs by the arms; 70 received 12-13.2 Gy, given in 6-11 fractions, 2-3 fractions per day (HFTBI): in this case about 2/3 of the lungs were shielded by moulded blocks (mean shielded lung dose equal to 9 or 9.5 Gy). Thirteen patients received 8 Gy given in a single fraction (SFTBI, lung dose: 7 Gy). For all HFTBI and FTBI patients, midline in-vivo dosimetry was performed at the first fraction by positioning two diodes pairs (one at entrance and one at the exit side) at the waist (umbilicus) and at the pelvis (ankles). If at least one of the two diodes doses (waist-pelvis) was outside +/-5% from the prescribed dose, actions could be initiated, together with possible checks on the following fractions. Transit dosimetry by portal films was performed for most patients; for 165 of them (117 and 48, respectively for FTBI and HFTBI) the midline in-vivo dose distribution of the chest region was derived and mean lung dose assessed. As a CT plan was performed for all HFTBI patients, for these patients, the lung dose measured by portal in-vivo dosimetry was compared with the expected value. RESULTS: Concerning all diodes data, 528 measurements were available: when excluding the data of the first fraction(s) of the patients undergoing corrections (n = 392), mean and SD were respectively 0.0% and 4.5% (FTBI: -0.3 +/- 4.8%; HFTBI: 0.4 +/- 3.9%). In total 105/229 patients had a change after the first fraction and 66/229 were controlled by in-vivo dosimetry for more than one fraction. Since January 1998 a CT plan is performed for FTBI patients too: when comparing the diodes data before and after this date, a significant improvement was found (i.e. rate of deviations larger than 5% respectively equal to 30.7% and 13.1%, P = 0.007). When considering only the patients with a CT plan, the global SD reduced to 3.5%. Concerning transit dosimetry data, for FTBI, the mean (midline) lung dose was found to vary significantly from patient to patient (Average 9.13 +/- 0.81 Gy; range 7.4-11.4 Gy); for the HFTBI patients the mean deviation between measured and expected lung dose was 0.0% (1 SD = 3.8%). CONCLUSIONS: In vivo dosimetry is an effective tool to improve the accuracy of TBI. The impact of CT planning for FTBI significantly improved the accuracy of the treatment delivery. Transit dosimetry data revealed a significant inter-patient variation of the mean lung dose among patients undergoing the same irradiation technique. For patients with partial lung shielding (HFTBI), an excellent agreement between measured and expected lung dose was verified.     

单中心上下半野照射鼻咽癌颈部剂量分布的研究

目的：对单个等中心上下半野照射鼻咽癌颈部剂量分布特征进行研究。方法：在加速器上用6MV X射线分别按常规技术和单个等中心上下半野技术方法对剂量体模进行模拟照射，用热释光和胶片剂量仪测出面颈野和颈锁野衔接层面相关剂量及剂量重叠情况。对用2种照射技术治疗的2组患者定时拍摄验证片比较摆位重要性。结果：热释光测量结果显示单中心技术在照射野衔接层面平均剂量（1．01Gy)接近剂量DT1 Gy，而常规分野技术在照射野衔接层面平均剂量（1．09－1．13Gy)有10％左右的超出，胶片显示单中心技术照射在颈部的等剂量分布较均匀合理，无明显高剂量区出现。验证片证实单中心技术的照射野重叠（1mm)和摆位偏移（0.5mm)很小，分别优于常规分野技术（6－14mm和3mm）。结论：单中心上下半野照射技术在照射野衔接处可以得到比较准确和均匀的剂量分布，减少了摆位误差并有较好的摆位重复性，是一种值得推广的照射技术。     

全身照射治疗中的半导体剂量监测

对患者进行照射现场中的剂量监测是放射治疗质量保证和质量控制的最有效的措施之一,文章结合工作实践,探讨如何有效地进行X射线全身照射过程中的半导体剂量监测.