Is dose escalation achievable for esophageal carcinoma?

Aim

To investigate the feasibility of dose escalation using rapid arc (RA) and Helical Tomotherapy (HT) for patients with upper, middle and distal esophageal carcinomas, even for large tumor volumes.

Background

In esophageal cancer, for patients with exclusive radio-chemotherapy, local disease control remains poor. Planning study with dose escalation was done for two sophisticated modulated radiotherapy techniques: Rapid arc against Tomotherapy.

Materials and methods

Six patients treated with a RA simultaneous integrated boost (SIB) of 60 Gy were re-planned for RA and HT techniques with a SIB dose escalated to 70 Gy. Dose volume histogram statistics, conformity indices and homogeneity indices were analyzed. For a given set of normal tissue constraints, the capability of each treatment modality to increase the GTV dose to 70 Gy was investigated.

Results

Either HT or VMAT may be used to escalate the dose delivered in esophageal tumors while maintaining the spinal cord, lung and heart doses within tolerance. Adequate target coverage was achieved by both techniques. Typically, HT achieved better lung sparing and PTV coverage than did RA.

Conclusions

Dose escalation for esophageal cancer becomes clinically feasible with the use of RA and HT. This promising result could be explored in a carefully controlled clinical study which considered normal tissue complications and tumor control as endpoints.     

Novel X-ray image noise reduction technology reduces patient radiation dose while maintaining image quality in coronary angiography

Aims

The consequences of high radiation dose for patient and staff demand constant improvements in X-ray dose reduction technology. This study assessed non-inferiority of image quality and quantified patient dose reduction in interventional cardiology for an anatomy-specific optimised cine acquisition chain combined with advanced real-time image noise reduction algorithms referred to as ‘study cine’, compared with conventional angiography.

Methods

Fifty patients underwent two coronary angiographic acquisitions: one with advanced image processing and optimised exposure system settings to enable dose reduction (study cine) and one with standard image processing and exposure settings (reference cine). The image sets of 39 patients (18 females, 21 males) were rated by six experienced independent reviewers, blinded to the patient and image characteristics. The image pairs were randomly presented. Overall 85 % of the study cine images were rated as better or equal quality compared with the reference cine (95 % CI 0.81–0.90). The median dose area product per frame decreased from 55 to 26 mGy.cm²/frame (53 % reduction, p < 0.001).

Conclusion

This study demonstrates that the novel X-ray imaging technology provides non-inferior image quality compared with conventional angiographic systems for interventional cardiology with a 53 % patient dose reduction.     

非静脉曲张上消化道出血不同剂量奥美拉唑治疗的疗效比较

目的:比较不同剂量奥美拉唑治疗非静脉曲张上消化道出血的疗效。方法:选取2012年1月至2013年8月已被收治的符合标准的病例共256例非静脉曲张上消化道出血患者随机按知情同意原则分为治疗组(128例)和对照组(128例)两组,治疗组给予大剂量奥美拉唑治疗,对照组给予常规剂量奥美拉唑治疗,比较两组患者的临床疗效并记录分析两组患者治疗前后各观察指标有无统计学差异,并于治疗72小时后评估两组患者的胃内pH值及不良反应发生情况。结果:治疗组临床疗效优于对照组(P0.05),但是各指标改善情况、胃内Ph值及不良反应发生情况与对照组相近(P0.05)。结论:大剂量奥美拉唑治疗非静脉曲张上消化道出血有良好的临床疗效。     

Pretreatment verification of dose calculation and delivery by means of measurements with PLEXITOM™ phantom

Aim

To validate a pretreatment verification method of dose calculation and dose delivery based on measurements with Metaplex PTW phantom.

Background

The dose-response relationships for local tumor control and radiosensitive tissue complications are strong. It is widely accepted that an accuracy of dose delivery of about 3.5% (one standard deviation) is required in modern radiotherapy. This goal is difficult to achieve. This paper describes our experience with the control of dose delivery and calculations at the ICRU reference point.

Materials and methods

The calculations of dose at the ICRU reference point performed with the treatment planning system CMS XiO were checked by measurements carried out in the PLEXITOM™ phantom.All measurements were performed with the ion chamber positioned in the phantom, at the central axis of the beam, at depth equivalent to the radiological depth (at gantry zero position). The source-to-phantom surface distance was always set to keep the source-to-detector distance equal to the reference point depth defined in the ICRU Report 50 (generally, 100 cm). The dose was measured according to IAEA TRS 398 report for measurements in solid phantoms. The measurement results were corrected with the actual accelerator''s output factor and for the non-full scatter conditions. Measurements were made for 111 patients and 327 fields.

Results

The average differences between measurements and calculations were 0.03% (SD = 1.4%), 0.3% (SD = 1.0%), 0.1% (SD = 1.1%), 0.6% (SD = 1.8%), 0.3% (SD = 1.5%) for all measurements, for total dose, for pelvis, thorax and H&N patients, respectively. Only in 15 cases (4.6%), the difference between the measured and the calculated dose was greater than 3%. For these fields, a detailed analysis was undertaken.

Conclusion

The verification method provides an instantaneous verification of dose calculations before the beginning of a patient''s treatment. It allows to detect differences smaller than 3.5%.     

One size does not fit all: Factors associated with increased frequency of radiation overexposure alerts based on fixed-alert thresholds

ObjectivesQuantify the expected rate of CT radiation dose alerts for three body regions using accepted radiation dose benchmarks and assess key determinants of alert frequency.MethodsThis IRB-approved retrospective cohort study evaluated consecutive CT examinations performed between July and December 2013 within an academic medical system. CTDI_vol x-ray tube output metrics were compared to the body-region-specific benchmark levels, Achievable Doses (AD), Diagnostic Reference Levels (DRL), and Dose Notification Values (DNV). A logistic regression model for the simulated alerts was fit as a function of the independent predictors: scanner, body region, gender, weight, and age.ResultsFor 17,000 exams, the proportion of events triggering alerts increased with patient weight. Significant covariates were scanner, body region, patient weight and patient age (all p < 0.0001). Odds of alert generation for the AD, DRL, and DNV benchmarks increased by 7.6%, 6.6% and 2.9% per kilogram, respectively, and by 0.8%, 1.1% and −2.7% per year of age (all p < 0.0001). Compared to the most highly optimized scanner, odds of alert generation varied by a factor of 595 for AD, 1126 for DRL, and 13 for DNV.ConclusionAlert frequency was significantly correlated with weight, age, body region and scanner. Controllable factors include scanner functionality and associated protocol optimization. Patient factors driving alert frequency are predominantly weight, and to a lesser degree, age. Size-agnostic fixed dose thresholds can frequently produce false positive alerts in appropriately performed exams of large patients, while missing opportunities to identify outlier scans of higher-than-expected dose in small patients.     

Dose calculation validation of a convolution algorithm in a solid water phantom

PurposeThe dose calculated using a convolution algorithm should be validated in a simple homogeneous water-equivalent phantom before clinical use. The dose calculation accuracy within a solid water phantom was investigated.MethodsThe specific Gamma knife design requires a dose rate calibration within a spherical solid water phantom. The TMR10 algorithm, which approximates the phantom material as liquid water, correctly computes the absolute dose in water. The convolution algorithm, which considers electron density miscalculates the dose in water as the phantom Hounsfield units were converted into higher electron density when the original CT calibration curve was used. To address this issue, the electron density of liquid water was affected by modifying the CT calibration curve. The absolute dose calculated using the convolution algorithm was compared with that computed by the TMR10. The measured depth dose profiles were also compared to those computed by the convolution and TMR10 algorithms. A patient treatment was recalculated in the solid-water phantom and the delivery quality assurance was checked.ResultsThe convolution algorithm and the TMR10 calculate an absolute dose within 1% when using the modified CT calibration curve. The dose depth profile calculated using the convolution algorithms was superimposed on the TMR10 and measured dose profiles when the modified CT calibration curve was applied. The Gamma index was better than 93%.ConclusionsDose calculation algorithms, which consider electron density, require a CT calibration curve adapted to the phantom material to correctly compute the dose in water.     

不同放射剂量CT在早期非小细胞肺癌中筛检价值对比

摘要 目的：探讨与对比不同放射剂量计算机断层扫描(Computed Tomography,CT)在早期非小细胞肺癌中筛检价值。方法：2020年1月到2020年12月选择在本院经病理确诊为肺内磨玻璃样结节患者98例作为研究对象,所有患者都给予常规剂量正电子发射计算机断层扫描(Positron emission tomography,PET)/CT检查与低剂量PET/CT检查,记录成像特征、辐射剂量并判定筛检价值。结果：低剂量PET/CT对肺部增厚、边界不规则、钙化、囊变的检出率高于常规剂量PET/CT(P<0.05)。低剂量PET/CT与常规剂量PET/CT的图像质量优良率为98.0 %和96.9 %,对比差异无统计学意义(P>0.05)。低剂量PET/CT的有效放射剂量、剂量长度乘积低于常规剂量PET/CT(P<0.05)。低剂量PET/CT的最大标准摄取值(maximum standardized uptake value,SUVmax)值低于常规剂量PET/CT(P<0.05)。低剂量PET/CT与常规剂量PET/CT分别筛检非小细胞肺癌51例与37例,筛检敏感性分别为98.1 %和69.2 %,特异性分别为100.0 %和97.8 %。结论：低放射剂量PET/CT在肺结节中的应用不会影响图像质量,且能降低辐射剂量,提高对早期非小细胞肺癌患者的筛检效果。     

木丹颗粒联合羟苯磺酸钙胶囊对糖尿病周围神经病变患者神经传导速度、血液流变学和氧化应激的影响

摘要 目的：探讨木丹颗粒联合羟苯磺酸钙胶囊对糖尿病周围神经病变（DPN）患者神经传导速度、血液流变学和氧化应激的影响。方法：选取2018年9月~2020年8月期间我院收治的120例DPN患者。按照随机数字表法分为观察组（60例,木丹颗粒联合羟苯磺酸钙胶囊治疗）和对照组（60例,羟苯磺酸钙胶囊治疗）,均治疗8周。对比两组疗效、神经传导速度、血液流变学和氧化应激,记录两组不良反应发生情况。结果：观察组的临床总有效率高于对照组（P<0.05）。观察组治疗后正中神经、腓总神经的运动传导速度（MNCV）和感觉传导速度（SNCV）均较治疗前升高,且高于对照组（P<0.05）。两组治疗后全血低切黏度、全血高切黏度、纤维蛋白原、血浆黏度均较治疗前降低,且观察组低于对照组（P<0.05）。两组治疗后丙二醛（MDA）较治疗前降低,超氧化物歧化酶（SOD）较治疗前升高（P<0.05）,且观察组MDA较对照组低,SOD较对照组高（P<0.05）。两组不良反应发生率对比无明显差异（P>0.05）。结论：木丹颗粒联合羟苯磺酸钙胶囊治疗DPN患者疗效确切,可提高患者神经传导速度和抗氧化应激能力,改善血液流变学状态,安全可靠。     

Inactivation of Crotalus atrox venom hemorrhagic activity by direct current exposure using hens' egg assay

The hemotoxic venoms of Viperidae and Crotalidae are responsible for most of the evenomations in the United States, West Africa, India, South-East Asia, New Guinea, and Latin America. We previously reported that a short exposure of Crotalus atrox venom to direct electric current (dc) from a low-voltage generator, in solution, causes consistent and irreversible inactivation of venom phospholipase A(2) and metalloproteases. Here we report by in vivo assay on chicken embryos at stage 18 of development according to Hamburger and Hamilton that the hemorrhagic activity of C. atrox venom is lost after exposure to dc (from low voltage). Venom was exposed to dc ranging between 0 and 1 mA. dc values above 0.7 mA abolished hemorrhage. Such in vivo data, showing that dc neutralizes C. atrox venom hemorrhagic activity suggest that a deeper knowledge is needed to understand the relationship among dc and biological matter.