An investigation of the IQM signal variation and error detection sensitivity for patient specific pre-treatment QA

PurposeTo evaluate the Integral Quality Monitor (IQM) as a clinical dosimetry device for detecting photon beam delivery errors in clinically relevant conditions.Materials and methodsThe IQM’s ability to detect delivery errors introduced into clinical VMAT plans for two different treatment sites was assessed. This included measuring 103 nasopharynx VMAT plans and 78 lung SBRT VMAT plans with introduced errors in gantry angle (1–5°) and in MLC-defined field size and field shift (1–5 mm). The IQM sensitivity was compared to ArcCheck detector performance. Signal dependence on field position for on-axis and asymmetrically offset square field sizes from 1 × 1 cm² to 30 × 30 cm² was also investigated.ResultsThe IQM detected almost all introduced clinically-significant MLC field size errors, but not some small gantry angle errors or most MLC field shift errors. The IQM sensitivity was comparable to the ArcCheck for lung SBRT, but worse for the nasopharynx plans. Differences between IQM calculated/predicted and measured signals were within ± 2% for all on-axis square fields, but up to 60% for the smallest asymmetrically offset fields at large offsets.Conclusion The IQM performance was consistent and reproducible. It showed highest sensitivity to the field size errors for these plans, but did not detect some clinically-significant introduced gantry angle errors or most MLC field shift errors. The IQM calculation model is still being developed, which should improve small offset-field performance. Care is required in IQM use for plan verification or online monitoring, especially for small fields that are off-axis in the detector gradient direction.     

An institutional experience of quality assurance of a treatment planning system on photon beam

Aim

The purpose of the present study is to show the application of the IAEA TRS-430 QA procedures of Eclipse™v7.5 TPS for photon energies. In addition, the trends of the deviations found in the conducted tests were determined.

Background

In the past, the lack of complete TPS QA procedures led to some serious accidents. So, QA in the radiotherapy treatment planning process is essential for determination of accuracy in the radiotherapy process and avoidance of treatment errors.

Materials and methods

The calculations of TPS and measurements of irradiations of the treatment device were compared in the study. As a result, the local dose deviation values (δ₁: central beam axis, δ₂: penumbra and build up region, δ₃: inside field, δ₄: outside beam edges, δ_50–90: beam fringe, RW₅₀: radiological width) and their confidence limit values (including systematic and random errors) were obtained.

Results

The confidence limit values of δ₄ were detected to increase with expanding field size. The values of δ₁ and δ₃ of hard wedge were larger than open fields. The values of δ₂ and δ_50–90 of the inhomogeneity effect test were larger, especially than other tests of this study. The average deviation was showed to increase with the rise of the wedge angle. The values of δ₃ and δ₄ of lung irradiation were outside tolerance.

Conclusions

The QA of TPS was done and it was found that there were no reservations in its use in patient treatment. The trend of the deviations is shown.     

Reduced mitochondrial and ascorbate–glutathione activity after artificial ageing in soybean seed

The effect of artificial ageing on the relationship between mitochondrial activities and the antioxidant system was studied in soybean seeds (Glycine max L. cv. Zhongdou No. 27). Ageing seeds for 18 d and 41 d at 40 °C reduced germination from 99% to 52% and 0%, respectively. In comparison to the control, malondialdehyde content and leachate conductivity in aged seeds increased and were associated with membrane damage. Transmission electron microscopy and Percoll density gradient centrifugation showed that aged seeds mainly contained poorly developed mitochondria in which respiration and marker enzymes activities were significantly reduced. Heavy mitochondria isolated from the interface of the 21% and 40% Percoll were analyzed. Mitochondrial antioxidant enzymes activities including superoxide dismutase, ascorbate peroxidase, glutathione reductase, monodehydroascorbate reductase, and dehydroascorbate reductase were significantly reduced in aged seeds. A decrease in total ascorbic acid (ASC) and glutathione (GSH) content as well as the reduced/oxidized ratio of ASC and GSH in mitochondria with prolonged ageing showed that artificial ageing reduced ASC–GSH cycle activity. These results suggested an elevated reactive oxygen species (ROS) level in the aged seeds, which was confirmed by measurements of superoxide radical and hydrogen peroxide levels. We conclude that mitochondrial dysfunction in artificially aged seeds is due to retarded mitochondrial and ASC-GSH cycle activity and elevated ROS accumulation.     

制备低剂量四氯化碳诱导小鼠慢性肝损伤模型的探讨

目的：通过注射低剂量四氯化碳（ carbon tetrachloride ,CC14）建立B/C小鼠肝损伤模型。方法正常B/C小鼠随机分为正常对照组、油对照组、CCl4模型组。正常对照组常规饲养;油对照组腹腔注射鲁花花生油（10μL/g,1次/3天,连续6周）;CC14模型组腹腔注射0.5％CC14（10μL/g,1次/3天,连续6周）。第6周,各组小鼠检测血清AST、ALT浓度,HE及Masson染色后观察小鼠肝脏结构、细胞形态及纤维化程度。结果第6周CCl4模型组小鼠血清ALT（P＝0.00）、AST（P＝0.00）浓度极显著性增高,HE及Masson染色显示CCl4模型组小鼠肝上皮细胞呈广泛性空泡样变及大量坏死,肝小叶内出现明显的条索样纤维增生,其纤维化程度评分显著性升高（P ＝0.00）,纤维显色积分光密度值极显著性增高（P ＝0.00）。结论注射低剂量CCl4可以诱导B/C小鼠肝损伤模型,实验模型具备肝损伤和肝纤维化病理特征。     

Analysis and reduction of thermal dose errors in MRgFUS treatment

ExAblate 2000 MRgFUS system (InSightec) installed in Ospedale Maggiore Niguarda Ca' Granda (Milano, Italy) is currently used to treat uterine fibroids. Through the magnetic resonance thermometry (PRF method), it is possible to monitor the temperature in the target in real-time and compute the treated region calculating the thermal dose. The purpose of this work is to investigate the errors in the temperature measurements and their effect on thermal dose. A low pass filtering of temperature maps is proposed to reduce the errors and therefore to improve the reliability of the treated regions calculated.The PRF method was studied through a calibration experiment on ex vivo pig muscle. The outcome resulted to be a very good linearity (p value 0.03) between phase and temperature in the range of interest, and an α value of −0.0109 ± 0.0002 ppm/°C. Temperature statistical uncertainty was evaluated by analyzing the temperature readout variability in specific gel provided by InSightec for daily quality assurance control. It resulted to be 1.89 ± 0.32 °C.A Monte Carlo simulation of the MRI temperature measurement and thermal dose calculations in our specific conditions of geometry and statistical uncertainty revealed that a low-pass filtering process on each temperature map can strongly reduce systematic errors in thermal dose evaluations (1.11 overestimation factor instead of 2.62 without filter); consequently the systematic errors on the size of the predicted ablated area are reduced as well.     

长期应用小剂量激素对类风湿关节炎患者的临床疗效及安全性研究

目的:分析长期使用小剂量激素治疗类风湿关节(RA)炎的临床效果及安全性,并探讨小剂量激素的使用方法。方法:将49例RA患者随机分为两组,治疗组使用改变病情抗风湿药物(DMARD)及激素泼尼松7.5 mg/d,对照组给予DMARDs。观察和比较两组患者在不同治疗时间的临床缓解情况及不良反应的发生率。结果:最终49例患者完成实验(治疗组22例,对照组27例)。治疗第12周时,治疗组的DAS28评分显著低于对照组,差异有统计学意义(P0.05);治疗24、48周时,两组的DAS28评分比较均无统计学差异(P0.05)。在治疗第12周时,治疗组的ACR20达标率显著高于对照组(P0.05);在治疗第24、48周时,两组的的ACR20达标率相比无统计学差异(P0.05)。治疗12、24周时,两组体重增加的发生率比较无统计学差异(P0.05)。但在治疗48周时,治疗组体重增加的发生率显著高于对照组(P0.05);两组胃肠不适及血压升高的发生率相近,且均未发现血糖升高的患者。结论:与单纯使用DMARDs相比,长期(大于24周)应用小剂量激素对RA患者临床症状的缓解作用不明显,但安全性尚可。     

Comparative assay of Vipera ammodytes antivenom potency

The finding of the most appropriate way to assess precisely the antivenom efficacy represents one of the major issues for antivenom standardization and success increasing of antivenom therapy. The efficacy of experimental Vipera ammodytes antivenom raised in sheep was determined using in vivo mouse lethality test, respectively, L-aminoacid oxidase, total proteinase and phospholipase A₂ antienzymatic effectiveness. The values gained for the antivenom potency depend on the method of measure. So, some of the most toxic venom proteins own phospholipase A₂ activity and provide the highest antivenom potency (lowest effective dose) values by antienzymatic assay method. This value is similar with total antiproteolytic antivenom potency value, but almost three times higher than value obtained by L-aminoacid oxidase (low toxic viper venom protein) antienzymatic assay method.     

Long-term low-dose α-particle enhanced the potential of malignant transformation in human bronchial epithelial cells through MAPK/Akt pathway

Since the wide usage of ionizing radiation, the cancer risk of low dose radiation (LDR) (<0.1 Gy) has become attractive for a long time. However, most results are derived from epidemiologic studies on atomic-bomb survivors and nuclear accidents surrounding population, and the molecular mechanism of this risk is elusive. To explore the potential of a long-term LDR-induced malignant transformation, human bronchial epithelial cells Beas-2B were fractionally irradiated with 0.025 Gy α-particles for 8 times in total and then further cultured for 1–2 months. It was found that the cell proliferation, the abilities of adhesion and invasion, and the protein expressions of p-ERK, p-Akt, especially p-P38 were not only increased in the multiply-irradiated cells but also in their offspring 1–2 months after the final exposure, indicating high potentiality of cell malignant transformation. On opposite, the expressions of p-JNK and p-P66 were diminished in the subcultures of irradiated cells and thus may play a role of negative regulation in canceration. When the cells were transferred with p38 siRNA, the LDR-induced enhancements of cell adhesion and invasion were significantly reduced. These findings suggest that long-term LDR of α-particles could enhance the potential of malignant transformation incidence in human bronchial epithelial cells through MAPK/Akt pathway.     

Proactive rectal warming during total-gland prostate cryoablation

Purpose

Proactive rectal warming (PRW), as a modification of prostate cryoablation, was assessed in terms of rectal complications and therapeutic outcomes.

Materials and methods

A cohort of 166 patients cumulatively treated between September, 2009 and November, 2012 qualified for study, each undergoing total-gland cryoablation (TGC) for prostate cancer. The initial 100 patients accrued submitted to TGC alone. PRW was administered to the final 66 patients. Preemptive warming is achieved by inserting a cryoprobe midline through perineal skin into anterior rectal wall under ultrasound guidance. The activated probe generates warmth as the ice ball encroaches on rectum. Prospective, post-ablative grading of rectal pain was measured at weeks 1, 2, 4, 8, 12, and 24 by using the Common Terminology Criteria for Adverse Events. Recurrent prostate cancer was gauged by Phoenix criterion (nadir + 2 ng/ml). The Mann–Whitney U test and Chi-square test were used to compare clinical characteristics of therapeutic subsets. The Cox proportional hazard model was applied for comparison of cancer recurrence risk by group.

Results

Rectal pain (all grades) was experienced by patients treated with (62%) and without (74%) PRW. Although such pain typically resolved with time, it was milder (general lineal model, p = 0.023) and less prolonged (median: 0.75 vs 1.5 months; log-rank test, p = 0.002) in patients receiving PRW than in controls. Of note, PRW did not heighten cancer recurrence risk (hazard ratio = 1.3 [95% CI, 0.3–5.0]).

Conclusions

PRW helps to protect the rectum from freeze injury during prostate cryoablation, significantly reducing post-ablative rectal pain without compromising therapeutic outcomes.