工业X射线探伤防护剂量水平的研究

本文介绍了用实验方法研究不同管电压, 钢板厚度与散射线之间的关系.结果表明, 透射比随管电压升高而增加, 并随钢板厚度增加而下降；散射比随散射角的增大而逐渐下降, 至180°时为最低值。此研究为X射线探伤作业的辐射防护提供了依据。     

采用儿童仿真模体研究胸部DR不同千伏照射下的有效剂量

目的 采用1岁儿童仿真模体计算胸部数字化摄影（DR）不同千伏条件下儿童各组织、器官的吸收剂量，估算并比较不同千伏下有效剂量。方法 塑料管分装的热释光剂量计（TLD）布放入儿童模体预留的插孔，在60、 70、80和90 kV时，自动曝光控制（AEC）模式下各曝光20次，然后回收TLD，回实验室测量。计算出不同千伏下组织、器官的吸收剂量，并分别估算出受照儿童模体全身有效剂量。结果 在60、70、80和90 kV时照射野范围内各组织、器官随千伏的增高吸收剂量逐渐降低。4个实验组中有效剂量分别为0.43、0.34、0.29和0.23 μSv。结论 儿童模体胸部摄影使用较高千伏可减少组织、器官的吸收剂量和全身有效剂量。     

^60Coγ射线放疗水平二级剂量标准的TLD国际比对

目的通过参加IAEA/WHO组织的TLD国际比对,检查二级标准剂量学实验室（SSDL）放疗水平剂量标准和国际标准的一致性。方法 SSDL对IAEA邮寄的TLD进行照射,并计算出其吸收剂量,然后将TLD及其计算结果寄往IAEA剂量学实验室,IAEA对其进行评价后给出比对的偏差。结果本次60Coγ射线吸收剂量比对的偏差为-1.8%。结论按照IAEA要求,该项比对的最大允许偏差为±3.5%,所以这次比对结果是合格的。     

Assessment of the radiological safety of a Genoray portable dental X-ray unit

Objectives:

The portable dental radiographic systems are generally used in emergency situations (e.g. during natural disasters) for disabled/aged patients and in patient rooms. This study assesses the output exposure of a portable dental radiographic system measured using thermoluminescent dosemeters (TLDs).

Methods:

Occupational exposure of the operator was determined when the portable dental unit was used for mandibular and maxillary teeth exposure.

Results:

The doses of some critical organs of an operator were measured using TLDs implanted within the Rando phantom.

Conclusions:

Considering the annual organ dose limits, the eye lens dose limit is the main factor determining the frequency of system application.     

沙利度胺及其衍生物临床及作用机制研究进展

沙利度胺是一种合成的谷氨酸衍生物，原作为镇静剂治疗早孕反应，20世纪60年代出现严重的致胎儿缺陷而被禁止使用。但此后研究发现，沙利度胺具有免疫调节和抗血管生成作用，治疗多发性骨髓瘤等恶性肿瘤以及其他难治性疾病有效。通过对沙利度胺进行结构改造得到的一系列免疫调节药克服了原形药物的严重不良反应，这些药物的强大的抗癌作用意味着它们将走出沙利度胺的阴影，成为有效的抗肿瘤药物。现对沙利度胺及其衍生物的临床应用和作用机制的研究进展进行综述。     

Estimating the absorbed dose to critical organs during dual X-ray absorptiometry.

OBJECTIVE: The purpose of this study is to estimate a patient's organ dose (effective dose) during performance of dual X-ray absorptiometry by using the correlations derived from the surface dose and the depth doses in an anthropomorphic phantom. MATERIALS AND METHODS: An anthropomorphic phantom was designed and TLDs (Thermoluminescent Dosimeters) were placed at the surface and these were also inserted at different depths of the thyroid and uterus of the anthropomorphic phantom. The absorbed doses were measured on the phantom for the spine and femur scan modes. The correlation coefficients and regression functions between the absorbed surface dose and the depth dose were determined. The derived correlation was then applied for 40 women patients to estimate the depth doses to the thyroid and uterus. RESULTS: There was a correlation between the surface dose and depth dose of the thyroid and uterus in both scan modes. For the women's dosimetry, the average surface doses of the thyroid and uterus were 1.88 microGy and 1.81 microGy, respectively. Also, the scan center dose in the women was 5.70 microGy. There was correlation between the thyroid and uterus surface doses, and the scan center dose. CONCLUSION: We concluded that the effective dose to the patient's critical organs during dual X-ray absorptiometry can be estimated by the correlation derived from phantom dosimetry.     

Rectum dose analysis employing a multi-purpose brachytherapy phantom

PURPOSE: It is difficult to reproduce a brachytherapy measurement because of changes in the rectal shape during inter-fraction. We constructed a multi-purpose brachytherapy phantom (MPBP) and reproduced the same conditions found in actual therapy. We further attempted to apply the measured optimal dose to reduce rectal complications. METHODS: A measured dose was administered at rectal reference point R1 using a diode detector in four patients who used a tandem and ovoid in brachytherapy for carcinoma of the cervix. A total number of 20 rectal dose measurements were performed five times per patient. In addition, discrepancies in the set-up of the diode detector were analyzed with each repetitive measurement. After reproducing the same conditions as found in actual therapy using a multi-function applicator (MFA) in the multi-purpose brachytherapy phantom constructed for this study, the dose was measured at reference points in the rectum using a thermoluminescence dosimeter (TLD). RESULTS: According to the discrepancies measured in the set-up using a diode detector, Patient 1 showed a maximum value of 11.25 +/- 0.95 mm in the Y direction, Patients 2 and 3 exhibited 9.90 +/- 2.40 mm and 20.85 +/- 4.50 mm in the Z direction, respectively. Patient 4 showed 19.15 +/- 3.33 mm in the Z direction. In addition, values of the mean dose according to the position of the diode detector were recorded as 122.82 +/- 7.96-323.78 +/- 11.16 cGy. In the measured results for TLD in an MPBP, relative error for Patients 1 and 4 at the rectal reference point R2 were a maximum of 8.6 and 7.7%, respectively. For Patients 2 and 3 they were 1.7 and 1.2%, respectively. Furthermore, the dose measured at point R1 and R2 exhibited values approximately 1.7-8.6% higher than the dose calculated in advance, excluding point R1 in Patient 2. The discrepancies in the set-up owing to repetitive measurements and alterations in dosage according to these changes were not analyzed. It was evident that the relative error between the calculated and measured value was within 15%, which was allowable according to the recommendations by the American Association of Physicists in Medicine (AAPM). CONCLUSIONS: The multi-purpose brachytherapy phantom constructed for this study successfully reproduced an optimal dose measured under the same conditions found in actual therapy in which the dose was precisely analyzed at a rectal reference point. In addition, these results were considered reliable and applicable for dose optimization before applying therapy using the measured data from the phantom in order to reduce rectal complications.     

热释光剂量计核查非参考条件下放射治疗剂量学参数的研究

目的　用TLD核查在非参考条件下 ,光子束轴向和电子束轴向最大剂量点处 ,剂量随深度、距离、照射野和 4 5°楔形板等变化的临床剂量学参数研究。方法　在非参考条件下 ,TLD经6 0 Coγ射线束 ,6MV和 15MV高能X射线束 ,9MeV和 16MeV高能电子束测量并估算剂量。结果经TLD核查 ,对不同射线质在不同深度 ,用不同指型电离室测量 ,除了TLD在水中深度 2 0cm处应做支架减弱效应减弱校正外 ,其余临床剂量学参数核查结果表明 ,TLD测量结果与指型电离室测量的参考剂量结果相对误差值均在± 4 9% (IAEA允许误差± 5 % )以内 ;对高能电子线束 ,用平行板电离室测量 ,绝大多数TLD相对误差值超过± 5 %。结论　用TLD核查非参考条件下 ,放射治疗临床剂量学参数方便 ,准确可靠 ,经在医院做可行性验证 ,IAEA推荐的两种TLD照射支架 (一种用于光子束 ,另一种用于电子束 )具有可行性 ;对高能电子线束用平行板电离室测量 ,TLD验证方法待做进一步研究。     

Implementation of a blood irradiation program at a community cancer center

BACKGROUND: Blood component irradiation is an accepted method of preventing transfusion-associated GVHD. Previous publications have largely focused on the technical aspects of the irradiation process itself, but relatively little attention has been paid to the details associated with the implementation of a blood irradiation program at the level of a community cancer center. STUDY DESIGN AND METHODS: An observational study was performed, detailing the specific operational, documentation, and quality assurance measures employed in providing a blood component-irradiation service within the institutional context of a community cancer center. RESULTS: The Montgomery Cancer Center irradiated 589 units of blood components in 1998 and 1999 to provide a local blood bank with an alternative for procurement of irradiated blood components while complying with applicable quality assurance and regulatory requirements. CONCLUSION: Blood component irradiation is within the scope of most well-equipped and adequately staffed community cancer centers. Establishment of a blood component irradiation program requires scrupulous physics and dosimetry support, both to ensure the quality of the irradiated component and to satisfy governmental agency regulatory requirements.     

Sensitivity and stability of LiF thermoluminescence dosimeters

Three different batches of LiF TLD-100 rods were subjected to investigation of their radiation sensitivity and the stability of the sensitivity after subsequent cycles of irradiation readouts. An old batch (circular rods from 1985), R85, showed an initial sensitivity of approximately 720 (nC/Gy). A new batch of circular rods (R0059) had an initial sensitivity more than a factor of 2.5 higher than the old batch. A batch of square rods (S3720) had an even higher sensitivity; a factor of almost 4 higher than batch R85. Both batches of circular rods showed a statistically significant change in sensitivity with increasing cycles of irradiations and readouts. No significant change was observed for the batch S3720. Batch R85 showed an increasing sensitivity with increasing number of cycles, and a small reduction in the width of the sensitivity distribution within the batch. However, the newer batch (R0059), showed a marked decrease in sensitivity and a doubling of the broadening of the sensitivity distribution after 10 cycles. No significant change in the sensitivity distribution within the S3720 batch was observed after 10 cycles.