三例大面积放疗病人染色体畸变率、微核率检测及全身等效剂量估算

为探讨在高度不均匀照射条件下 ,以微核 (ＭＮ)率和双 环 (ｄｉｃ ｒ)率所估算的相当于一次全身均匀受照剂量 ,我们用常规ＣＡ分析和ＣＢＭＮ法对接受全淋巴区、全腹和下半身放疗的 3例晚期肿瘤病人进行了外周血淋巴细胞ＣＡ率和ＭＮ率检测 ,比较了以ｄｉｃ ｒ率和ＭＮ率所估算的相当于一次全身均匀受照剂量。并针对ＣＢＭＮ法用作辐射生物剂量计时 ,其相对偏高的本底对剂量估算的影响进行了探讨。一、材料和方法1 病人 :接受全淋巴区、全腹和下半身6 0 Ｃｏγ射线放疗的 3例男性晚期肿瘤病人 ,中心平面剂量分别为 8、6和 6Ｇｙ。2 血样…     

低剂量^60Coγ线诱发淋巴细胞微核的剂量效应研究

用细胞浆分裂阻滞微核法（ＣＢＭＮ）研究了５名健康成人离体血＾６０Ｃｏγ线低剂量照射后的淋巴细胞中含微核细胞（ＭＮＣ）及微核（ＭＮ）的剂量效应关系。结果表明，在低剂量范围内，ＭＮＣ率及ＭＮ率均随照射剂量的增加而增加，并可配合出拟合度良好的二次多项式模型。该模型适合于单次或短期内多次外照射的剂量估算，可望成为检测剂量电离辐射的生物剂量计。结果还表明，应用ＭＮＣ率或ＭＮ率所能的最低剂量为０．０５Ｇｙ。当     

3例137Cs放射源事故受照人员的剂量估计

在一次¹³⁷Cs辐射源事故中,3个人在120～180天内受到多次全身不均匀照射,通过调查及模拟试验,确定了照射参数,并估计了身体中轴线剂量和等效全身均匀照射的剂量.     

头颈部照射血液及细胞遗传学变化的特点

头颈部照射血液及细胞遗传学变化的特点金玉珂，王明东，吕彩霞，邴文贵，孙晓玲，宫恩甲，陈德英，张贵荣，孙宝侠，王国印，金映辉急性全身均匀照射条件下，外周血液学改变和淋巴细胞染色体畸变率都与照射剂量相关，在一定剂量范围内随剂量的增加，变化更加明显．因此，...     

狗全身照射后淋巴细胞微核蜕减规律的探讨

狗全身照射后淋巴细胞微核蜕减规律的探讨蒋本荣，张海鹰，姚波淋巴细胞微核ＯＩ入）检测在核辐射事故受照者剂量估算中的重要性日益受到重视。国内一些学者相继以常规法及ＣＢ法建立了ＭＮ的剂量效应刻度曲线，用于临床，取得可喜的结果。由于射线诱发的ＭＮ主要源于染色...     

中度急性放射病的诊断

本文报道了40例中、晚期恶性淋巴瘤病人采用⁶⁰Coγ线一次全淋巴区照射6,8Gy的临床表现。若按病人外周血淋巴细胞染色体畸变估算这一剂量, 则相当于一次全身均匀照射条件下血液平均受照剂量分别为2.73～4.30Gy(平均3.55Gy)和3.48～5.58Gy(平均4.25Gy).按红骨髓千细胞法估算等效剂量为1.85～2.37Gy.可以见到中度急性放射病的临床经过, 表现为消化道反应和造血免疫功能受损, 骨髓受到抑制。白细胞, 血小板迅速减少, 淋巴细胞在早期就有质和量的变化。所有这些均是有意义的诊断指标。此外, 唇肌刺激反应、C反应蛋白、皮质醇, 尿中核苷和碱基, 照射前后皆有显着改变。因此利用肿瘤病人进行6～8Gy全淋巴区照射可以作出中度急性放射病的早期诊断。     

非均匀体模在剂量测定中的应用

本文介绍我们设计的非均匀人体模型在⁶⁰Coγ线辐射场中用热释光剂量测量方法测定体接内的吸收剂量,并参照ICRP26号出版物计算出人员全身拉德/伦值.各向均匀照射测量的结果可近似地用于天然本底辐射剂量的估算.     

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。     

细胞遗传学指标在慢性放射损伤诊断中的意义

用染色体畸变估算全身一次比较均匀的Ｘ、γ射线和中子的过量照射时的生物剂量比较准确 ,对不均匀和局部照射可给出相当于均匀照射的等效剂量当量。淋巴细胞微核也已被用作估算受照射剂量的指标 ,并取得了较为满意的结果。但在慢性放射损伤时 ,染色体畸变和微核的变化特点及其在慢性放射病诊断中的作用 ,是值得探讨和深入研究的问题。在《外照射慢性放射病诊断标准及处理原则》(ＧＢ82 81 87) [1] 中将“外周血淋巴细胞染色体畸变率显著增加和 /或外周血淋巴细胞微核率显著增加” ,作为慢性放射病诊断的参考指标。到目前为止 ,还不能用染色…     

组织不均匀条件对调强计划系统计算模型精度的影响

目的 探讨在组织不均匀条件下,治疗计划系统(MONACO)中的有限笔形束算法(FSPB)与快速X射线体积元蒙特卡罗算法(XVMC)的调强放射治疗计划计算精度差别,以及对临床治疗的影响和各自的应用范围。方法 在非均匀仿真人体模型中,对两种算法模型计算的规则照射野及调强照射野的剂量精度,利用经过刻度的放射性铬胶片(EBT2胶片),进行剂量测量以及二维平面剂量的分析比对。结果 在非均匀仿真人体模型中,不同能量的X射线规则照射野,XVMC算法在不同介质中的剂量计算与胶片测量的结果偏差均在±2.00%范围内,而FSPB计算的结果与测量结果的偏差除了15 MV射野为10 cm×2 cm情况下肺中的剂量偏差高达6.51%以外,其他条件下的结果偏差都在±3%范围内。调强放疗计划(IMRT)的胶片验证测量结果中,3%/3 mm γ通过率XVMC算法组>90%;FSPB算法组为80%~90%,且4%/4 mm γ通过率>90%。结论 当临床治疗病例的组织密度不均匀性较大、子野数较多时,XVMC算法的剂量计算精度优于FSPB算法,采用XVMC治疗设计胸腹部IMRT治疗计划可以将算法所引起的误差控制在±3%以内,而且可以避免由于算法原因所致的计划靶区剂量缺失。     

放射外照射事故剂量重建中的蒙特卡罗模拟方法

目的 建立放射外照射事故剂量重建的计算机系统。方法 基于MIRD的人体及其器官的数学模型，采用蒙特卡罗(MC)方法，结合 放射事故的受照模式，建立放射外照射事故剂量重建的计算机系统。结果 成功研制了放射事故剂量重建的计算机系统。用这个系统计算了河南省^60Co放射事故危重病人的剂量，其计算结果与实验模拟测量和生物剂量检测结果十分一致。结论 本系统方便、快捷，它不但可估算事故受照人员的器官剂量和全身剂量，而且也能用于事故早期剂量的估计。     

Utilization of a high energy photon beam for whole body irradiation.

Use of a high energy linear accelerator (giving high dose rates) for whole body irradiation is recommended because (a) there is a shorter treatment time compared with other techniques using orthovoltage or 60Co irradiation; and (b) there is more comfort for the patient, who does not have to turn over to receive an acceptably uniform dose. Dosimetry indicates that the usual data is not applicable for such treatments given at large distances from the source. A method of dosage calculation at large distances was checked by using TLD dosimetry in a Rando phantom.     

Dosimetry with phantom for total body irradiation(TBI)

Total body irradiation(TBI) is being used as a method of preparation for bone marrow transplantation(BMT). In TBI, the dose calculation is based on dosimetry using a phantom. We measured the basic dose with a phantom using a 10 MV X-rays. We confirmed the accuracy of the dose calculation performed in our facilities and investigated a method of more accurate dosimetry. We measured the variation in dose according to the size of the phantom and the depth using a tough water phantom, and examined the difference in TMR according to SCD, field size, and size of the phantom. Consequently, the dose has been changed regardless of the size of the phantom at larger than 80 x 30 x 30 cm(3), and it is about 1% larger than 30 x 30 x 30 cm(3). Also TMR has changed according to various conditions, including the size of the phantom, field size, and SCD. Therefore, it was found that dosimetry using the 30 x 30 x 30 cm(3) phantom leads to underestimation in dose calculation, and there is no difference in dose between the field size of 151.5 x 160 cm(2) and 151.5 x 80 cm(2). It is also necessary to consider the effect of the vertical size of the phantom.     

An isocentrically mounted stand for total body irradiation

The purpose of this study was to construct a stand to support a patient for total body photon irradiation and to expedite the set-up and treatment by rotating the stand. As in other isocentric treatments, the midline dose is impacted less by source-to-skin distance variations. The method of immobilizing the patient is described. A 10 mm lucite plate is supported in front of the patient to increase skin dose. A matrix of holes in this plate serves to index the location of blocks used to shield the lungs. The dosimetry of the set-up is described, as is the production of tissue deficit compensators. The results of phantom studies and in vivo thermoluminescent dosimetry measurements are presented.     

Estimation of the mean effective organ doses for total body irradiation from Rando phantom measurements.

For the total body irradiation (TBI) procedure, it is necessary to compare the mean dose obtained from the tissue or organs and the estimated dose equivalent value from the computer program. Due to the easy-access of the Rando phantom and repeatability of TLDs and its output, the results from the experiment are quite encouraging for the verification of the dose distributions from total body irradiation at the given prescribed monitor units. The estimation of effective dose equivalent particularly across the lung sections was studied by combinations of using arms as the scatter volume to compensate for the inhomogeneity across the breast portion, as well as using the spoiler for skin-sparing purposes. The results were based upon various beam quality such as 4 MV, 6 MV, and 10 MV X rays. One series of experiments performed for this survey to ascertain the dose equivalent of the tissues was conducted. This paper describes the method and procedure for comparison between the measured data and computed data as a reference in the dosimetry of total body irradiation. Comparison of the measured and computed data for the largest collimated field shows that the calculated dose rates do not differ by more than 2% from the measured data. Because uncertainty is inherent in non-patient-like phantoms, the calculated data may be served as a reference for the dosimetry. For the total body irradiation setup, considering the radiation field size and treatment distances commonly employed, we conclude that the best combination of the patient setup will be (1) laying both arms down as compensation for lung inhomogeneity, and (2) the spoiler, which is made of acrylic about 8 mm thick and functions like a bolus, is needed to reduce the skin sparing effects and contribute the uniform dose distribution. The beam spoiler with the frame stands near the patient during the treatment.     

Patient dosimetry for 131I-lipiodol therapy

Patient dosimetry data for intra-arterial()iodine-131 lipiodol therapy for hepatocellular carcinoma (HCC) are scarce. The aim of this study was to determine the absorbed dose (D) to the tumour and healthy tissues, as well as the effective dose (E), by different methods for 17 therapies in 15 patients who received a mean activity of 1.9 GBq (SD 0.2) (131)I-lipiodol. Eight patients received thyroid blocking by potassium iodide (KI). Patient dosimetry was performed based on bi-planar total body scans using the Monte Carlo simulation program MCNP-4B and the MIRDOSE-3 standard software program. CT images of each patient were used to determine liver and tumour volume and position. The total body dose to the patient was also determined by biological dosimetry with the in vitro micronucleus (MN) assay. From the increase in micronucleus yield after therapy, the equivalent total body dose (ETBD) was calculated. Results for D and E were comparable between MCNP and MIRDOSE (liver: mean 7.8 Gy, SD 1.8, lungs: 6.8 Gy, SD 2.9, E: 2.01 Gy, SD 0.58). MIRDOSE gave a systematic overestimation for the tumour dose, especially for tumours <3 cm (15%). The MCNP method is more accurate since the dose contributions from tumour to organs and vice versa can be accounted for. The absorbed dose to the thyroid was significantly lower for patients who received KI (7.2 Gy, SD 2.2) than for the other patients (13.8 Gy, SD 5.0). MN yields could be obtained for only 12 of the 17 therapies due to hypersplenism. A mean ETBD of 1.66 Gy (SD 0.73) was obtained, but the MN results showed no correlation between the ETBD and the total body dose values of the physical dosimetry. Also, in all except one of the patients, no further reduction in the number of thrombocytes was observed after therapy, probably due to the existing hypersplenism. It is concluded that in view of the high E values, patient dosimetry is necessary for patients receiving (131)I-lipiodol therapy. Except in the case of the smaller tumours, comparable results were obtained with MCNP and MIRDOSE. Due to hypersplenism, biological dosimetry results based on the MN assay are not reliable.     

胞浆分裂阻滞微核法对山东"10·21"辐射事故病人受照射剂量的估算

目的 对山东"10·21"辐射事故中2例严重受照射者进行淋巴细胞微核(MN)检测,并估算受照射剂量.方法 用胞浆分裂阻滞微核(CBMN)法对2例患者(A和B)的外周血和骨髓样本分别进行MN检测.结果 2例患者的外周血培养均未见双核淋巴细胞.患者A的骨髓培养所获双核细胞极少,依据双核淋巴细胞多少粗估剂量＞20Gy.患者B的骨髓MN率为2.42个/细胞,剂量估计为8.7(8.0～9.4)Gy,与用染色体畸变分析、物理方法及ESR法所估算剂量接近,与临床表现基本一致.结论 MN法简便快速,结果准确,是除染色体畸变分析之外又一种可靠的生物剂量计.     

Gonad dose in AP pelvis radiography: Impact of anode heel orientation

PurposeFor antero posterior (AP) pelvis radiographic examination, determine the impact of anode heel orientation on female/male gonad dose.MethodsHigh sensitivity thermo-luminescent dosimeters (TLDs) were used with an ATOM dosimetry phantom; the phantom was positioned for AP pelvis. TLDs were placed into the testes and ovaries. Radiation dose received by these organs was measured with the feet toward anode and feet toward the cathode. kVp, mAs and SID were manipulated to generate a range of exposures. A dose profile was also generated using Unfors Mult-O-Meter 401 along the long axis of the phantom.ResultsA decrease in dose from the central ray toward the anode was noted, with a marked increase toward the cathode. A significant reduction in dose was received by the testes with feet towards the anode compared with feet towards cathode (P˂0.001). No difference was seen for ovarian dose (P˃0.05). kVp, mAs and SID all have an effect on male and female gonad dose.ConclusionFor male pelvis imaging, placing feet towards the anode can be used as a simple dose reduction method.     

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.     

Chromosomal radiosensitivity study of temporary nuclear workers and the support of the adaptive response induced by occupational exposure

PURPOSE: To study chromosomal radiosensitivity in a population of radiation workers and investigate the possibility of an adaptive response in lymphocytes of workers after short-term occupational exposure to ionizing radiation. MATERIALS AND METHODS: The studied group comprised 41 workers temporarily employed at the Nuclear Power Plant Doel (Belgium) for reactor maintenance. A blood sample was taken before and directly after the exposure period of about 1 month. Chromosomal radiosensitivity was assessed in vitro by the G2 assay and the G0 micronucleus (MN) assay. For the MN assay, a low dose-rate (LDR) in vitro irradiation protocol was applied in addition to high dose-rate (HDR) irradiation of the blood samples in order to determine the dose-rate sparing (DRS) effect. RESULTS: No statistically significant effect of the occupational exposures (up to 10 mSv) on the baseline MN frequencies without in vitro irradiation was observed. A comparison of the number of chromatid aberrations pre- and post-exposure shows no effect of the occupational exposure. On the other hand, the G0-MN assay with the LDR irradiation protocol reveals a systematic reduction in chromosomal radiosensitivity by the exposure, increasing with dose. For workers who received the highest dose (4-10 mSv) a statistically significant (p <0.05) decrease of the in vitro induced MN yields and increase of the dose-rate sparing was observed. CONCLUSIONS: Short-term low-dose occupational exposure may act as an in vivo adaptive dose and stimulate repair in G0 lymphocytes.