Clinical Quality Control Research Articles

Electro-oxidation and Determination of Procainamide at Glassy Carbon Electrode and its Analytical Applications

An electrochemical method has been described for the voltammetric oxidation and determination of an antiarrhythmic drug, procainamide (PAH), at a glassy carbon electrode by using cyclic and differential pulse voltammetry (DPV) in phosphate buffer solution under physiological condition, i.e., pH = 7.0. The oxidation process was shown to be irreversible over the pH range studied. PAH undergoes two electron and one proton change and is a diffusion controlled process. The anodic peak current varied linearly with PAH concentration in the range 2.0 × 10-4 to 5.0 × 10-6 M with a limit of detection (LOD) of 1.966 × 10-6 M and limit of quantification (LOQ) 6.554 ×10-6 M. High percentage recovery and study of excipients showed that the method is free from the interferences of the commonly used excipients in the formulations of drug. The proposed method offered advantages of accuracy and time saving as well as simplicity of reagents and apparatus. This method can be employed in clinical analysis, quality control and routine determination of drugs in pharmaceutical formulations.

Validation of a Spectral Method for Quantitative Measurement of Color in Protein Drug Solutions.

In the biotechnology industry, a visual assessment is the most commonly used method for color characterization, batch release, and stability testing of liquid protein drug solutions. Using this method, an analyst visually determines the color of the sample by choosing the closest match to a standard color series. This visual method can be subjective because it requires an analyst to make a judgment of the best match of color of the sample to the standard color series, and it does not capture data on hue and chroma that would allow for improved product characterization and the ability to detect subtle differences between samples. To overcome these challenges, we developed a quantitative spectral method for color determination that greatly reduces the variability in measuring color and allows for a more precise understanding of color differences. In this study, we established a statistical method for assessing precision in 3-dimensional space and demonstrated that the quantitative spectral method is comparable with respect to precision and accuracy to the current European Pharmacopoeia visual assessment method.

Electrochemical oxidation of catecholamines on fluorine-doped SnO2 substrates. Square-wave voltammetric method for methyldopa determination in pharmaceutical dosage forms

An electrochemical study of methyldopa (MD), dopamine (DA) and adrenaline (AD) catecholamines was conducted using cyclic (CV) and square wave voltammetry (SWV). The pH-dependant electrochemical behavior of catecholamines was studied for the first time on fluorine doped tin oxide electrodes (FTO). The CV scan rate study showed the charge transfer process was diffusion controlled. Besides, electrochemical parameters such as diffusion coefficient, charge transfer coefficient and heterogeneous charge transfer rate constant were determined. The number of transferred electrons was 2. Furthermore, a method is proposed to determine MD in pharmaceutical preparations by SWV. Two linear ranges between 2.0·10−6 and 30.0 ·10−6molL−1 and 30.0·10−6 and 60.0·10−6molL−1 were found, with a limit of detection of 0.15·10−6 and 2.9·10−6molL−1, respectively. The method, displays good sensitivity and stability. This technique can be employed in clinical analysis, quality control and routine determination of drugs in pharmaceutical formulations.

A novel client service quality measuring model and an eHealthcare mitigating approach

ObjectivesFacing population ageing in Hong Kong, the demand of long-term elderly health care services is increasing. The challenge is to support a good quality service under the constraints faced by recent shortage of nursing and care services professionals without redesigning the work flow operated in the existing elderly health care industries.the existing elderly health care industries.1)Developing a model for measuring Total Quality of Services,2)Using the Total Quality of Services measure to assess staffing conditions, i.e. shortage or surplus, and to measure the effectives of catering new services,3)Incorporating Information and Communication Technologies (ICT) to mitigate the staff shortage problems and to enhance efficiency of care,4)Utilizing the Total Quality of Services measure to quantify the improvement and providing an indicator for services assessment in future. Methods1.Model DevelopmentWe use Finite Capacity Queuing Model to develop a model for Total Quality of Services and use the balk rate of the model to set up an efficiency rate. We then assume multiple independent queues existed in the model and calculate the accumulated efficiency rates to give The Total Quality of Services measure.2.Model SimulationWe conduct simulation on the model and check for its validity.3.ICT SolutionsTo keep up a desired quality service, we developed a “Residents Clinical Service Monitoring and Quality Control System” to test the appropriateness of the model. We designed the system to (i) make sure that clinical nursing care staff will run the nursing care protocol; (ii) cut substantially manual operation cost and possible human errors; (iii) give exception alerts for caring rules; (iv) promote efficient communication between staff and cost saving.4.Field TrialsWe carried out field trials for over 2 years and enhanced the system periodically. ResultsThe Total QoS measure based on Finite Capacity Queuing Model is a reliable method and an effective measurement for Quality of services. The value is good for measuring the staffing level and offers a measurement for efficiency enhancement when incorporate new technologies like ICT.The implemented system has improved the Quality of Service by more than 14% and the extra released manpower resource will allow clinical care provider to offer further value added services without actually increasing head count. ConclusionsWe have developed a novel Quality of Service measurement for Clinical Care services based on multi-queue using finite capacity queue model M/M/c/K/n and the measurement is useful for estimating the shortage of staff resource in a caring institution. It is essential for future integration with the existing widely used assessment model to develop reliable measuring limits which allow an effective measurement of public fund used in health care industries.

Comprehensive characterization of 412 muscle invasive urothelial carcinomas: Final analysis of The Cancer Genome Atlas (TCGA) project.

405 Background: We reported the integrated molecular analysis of 131 tumors in 2014 (Nature 507:315, 2014) and now report on the entire cohort of 412 tumors from the TCGA project in chemotherapy-naïve muscle invasive urothelial bladder cancer. Methods: Following strict clinical and pathologic quality control, tumors were analyzed for DNA copy number variants, somatic mutations (WES), DNA methylation, mRNA, microRNA and (phospho-) protein expression, transcript splicing, gene fusions, viral integration, pathway perturbation, clinical correlates, and histopathology Results: There was a high overall somatic mutation rate (8.0/Mb), as previously reported, with a median of 245 and mean of 348 coding region mutations per sample. There were 54 significantly mutated genes (SMGs) (MutSig_2CV), increased from 32 in the original report. TP53 remained the most commonly mutated gene, and chromatin-modifying genes (MLL2, ARID1A, KDM6A) were also frequently mutated. KRAS, ERBB2, RB1, and ELF3 showed significant increased frequencies of mutation. High mutation burden was associated with improved outcome (p = 0.0004). APOBEC mutagenesis explained 70% of the mutation burden and also was associated with survival. 167 genes were silenced by promoter DNA hypermethylation in at least 5% of tumors. Several SMGs were also epigenetically silenced at various frequencies (ZNF773, CDKN2A, FAT1, CASP8). The previously identified four mRNA subtypes were predicted on the larger set identifying a similar proportion of samples in each subtype. We identified 5 expression subtypes based on reverse-phase protein arrays(344 tumors). Five miR expression subtypes were strongly associated with 4 mRNA-based subtypes (P = 3.8E-37) and associated with overall survival (P = 0.05). Conclusions: This integrated analysis of 412 TCGA patient samples validates and extends observations from the first 131 patients and significantly increases our power to detect additional low-frequency aberrations. The results provide a robust basis for functional studies to further our understanding of the biology of bladder cancer, and aid in the development of more precisely targeted therapies.

Construction of an electrochemical sensing platform based on platinum nanoparticles supported on carbon for tetracycline determination

In this paper, we report the construction of an electrochemical sensing platform based on platinum nanoparticles supported on carbon (PtNPs/C) for the determination of the antibiotic tetracycline (TTC). Initially, the PtNPs/C was synthesized and characterized by powder X-ray diffraction spectroscopy and transmission electron microscopy. The effect of experimental parameters on the electrochemical behavior of the PtNPs/C coated glassy carbon electrode (PtNPs/C/GCE), including the amount of PtNPs and electroactive area, scan rate and pH, were evaluated. The electrooxidation of TTC on the PtNPs/C/GCE was investigated by cyclic voltammetry and differential pulse voltammetry, with the determination of TTC electrooxidation mechanism. Under optimum experimental conditions, the linear calibration range, detection limit, quantification and sensitivity of the PtNPs/C/GCE were 9.99–44.01μmolL−1, 4.28μmolL−1, 14.3μmolL−1 and 3.32μALμmol−1cm−2, respectively. Finally, the proposed electrochemical sensing platform was successfully applied to determine low TTC concentrations in urine samples, suggesting its great applicability in clinical analysis and quality control.

Chemical and Instrumental Approaches for Capillary Electrophoresis (CE)-Fluorescence Analysis of Proteins.

Capillary electrophoresis (CE) coupled to fluorescence detection is an invaluable technique for the quantitative analysis of proteins of interest in the field of clinical diagnosis and quality control of novel biotechnology products. The various chemical and instrumental approaches that have been reported to carry out such sensitive analysis are described in this paper. To illustrate the contribution of CE to the analysis of therapeutic proteins, a detailed protocol for impurities profiling of a recombinant antibody sample using CE-LEDIF is given.

Improving the clinical teaching quality control standard by optimizing the management of clinical practice record manual

Clinical practice record manual contains the information about medical students' clinical studying process, clinical teaching process and the concept of clinical teaching management. First, we should design and optimize clinical practice record manual and then collect and analyze the relevant data. In addition, we should give the analysis to the students, teachers, clinical departments and hospitals on time, and at the same time, get their feedback. Through these steps, we can find and solve the problem efficiently and promote the quality of teaching, learning and management of clinical internship, so as to improve the clinical teaching quality control standard. Key words: Clinical teaching; Clinical practice record manual; Data; Feedback; Quality

Construction and implementation of quality control index for clinical safety of Chinese medicine injection

In order to ensure the authenticity and accuracy of traditional Chinese medicine injection safety monitoring data, Chinese medicine injection safety monitoring quality control indicators, including the monitoring center, monitoring personnel, hardware conditions, monitoring progress and the number of patients into the group, original documents and archives management, electronic data, adverse events, quality management were constructed. Its application in the creation of major new drugs technology major projects, 10 kinds of traditional Chinese medicine injections clinical safety monitoring quality control work, found the missing case surveillance, not reported adverse events, only reported adverse reactions, electronic data reporting lag, lack of level of efforts to control the problem, and corrected, the traditional Chinese medicine injection safety monitoring of quality control and quality assurance, and subsequent Chinese medicine safety monitoring quality control to provide the reference.

Standardization efforts enabling next-generation sequencing and microarray based biomarkers for precision medicine.

Microarrays and next-generation sequencing technologies have been increasingly employed in biomedical research. However, before they can be reliably used as clinical biomarker tests, standardization and quality control measures need to be developed to ensure their analytical validity. This review summarizes community-wide efforts such as the MicroArray and Sequencing Quality Control (MAQC/SEQC) project which have identified factors influencing the performance of these technologies. Consequently, consensus-based standards and well-documented best practices have been developed to improve the quality of scientific research, and reference materials and reference datasets have been made available for evaluating the technical proficiency in future studies. These efforts have built the foundation on which the translational application of genomics based technologies can help realize precision medicine.

Improving structural development in oncology: transformation of theoretical health care standards and knowledge into a practical approach -- 2nd European Roundtable Meeting (ERTM), May 8, 2015, Berlin, Germany.

It is widely accepted that National Cancer Control Plans (NCCPs) are essential to improve cancer care. They often describe the structural requirements such as cancer centers, clinical cancer registries and quality control. During the 2nd European roundtable meeting, the implementation processes were analyzed and discussed. Communication strategies between cancer registries and cancer centers need to be developed. Analyses and discussion of collected data have to be performed by multidisciplinary teams. This has to be followed by appropriate actions to improve quality of care. It is essential to describe the clinical procedures, organizational processes and communication between individuals and professional teams. The patients' perspectives have to be included in the development of cancer care networks. The patients' feedback on cancer care is a routine quality indicator. NCCPs that include the description of structural requirements are important. In addition, it is essential to develop cancer care networks including multidisciplinary organizational processes to guarantee high quality. These have to consider patients preferences.

Occurrence and characterization of toxigenic Bacillus cereus in food and infant feces

ObjectiveTo investigate the true incidence of Bacillus cereus (B. cereus) in food and children diarrhea cases. MethodsA total of 110 samples of various dairy products such as raw milk, long life pasteurized milk, yoghurt and infant powdered milk formulas, raw rice, and feces were examined for the presence of B. cereus by selective plating on mannitol-egg-yolk-polymyxin agar. Confirmation of B. cereus was carried out by biochemical tests and PCR. Identification of non-B. cereus isolates was carried out by 16S rDNA sequencing. Antimicrobial susceptibility was done by disk diffusion method. ResultsOverall 35 samples (31.8%, n = 110) yielded Bacillus-like growth. Of which 19 samples (54.28%) were positive for B. cereus. All isolates were positive for enterotoxin production. No psychrotolerant B. cereus strains were detected in all samples. All B. cereus isolates were resistant to penicillin G, but susceptible to vancomycin, erythromycin and clindamycin. ConclusionsThe results of this study confirm the importance of including B. cereus in disease control and prevention programs, as well as in routine clinical and food quality control laboratories in both Saudi Arabia and Egypt.

Abstract 180: Coronary Artery Aneurysms Identified At School Cardiac Screening

Because most significant complication of Kawasaki disease (KD) is coronary aneurysms, echocardiography is an indispensable part of clinical practice and quality control of echocardiography is mandatory. On the other hand, Japanese government has enforced a law of regular school cardiac screening (SCS) at 1st, 7th, and 10th grader in 1995 and all patients with a history of KD were screened for coronary artery lesion. In this study we report 2 patients with coronary aneurysms picked up by SCS. Case1: A 6-year-old boy was diagnosed with KD at 3 year old and received immunoglobulin (2g/kg/day). His condition improved within 8 days of illness and echocardiographic finding of coronary artery was “normal” in acute phase and at 1and 3 months after the onset of KD. Since then he did not visit clinic for follow-up. At 1st grader SCS, he was diagnosed as having giant coronary artery aneurysms by echocardiography. Indeed coronary angiography revealed sequential coronary aneurysms of 10.8 mm and 12.3 mm in diameter at segment 6 and 5 with a 99% stenosis in between them. Because of signs of coronary ischemia on myocardial perfusion scan, he underwent percutaneous coronary interventions and coronary artery bypass graft surgery later. Case2: A 9-year-old boy was diagnosed with juvenile idiopathic arthritis and his fever continued 10 days. He underwent echocardiography at 9 days of illness but coronary artery lesions were not found. At 7th grader SCS, he was diagnosed as having coronary artery aneurysms by echocardiography. Coronary angiography revealed coronary artery aneurysms of 6.1mm and 6.1 mm in diameter at segment 1 and segment 6. Since then he has been placed on oral aspirin. These 2 cases highlight the issue concerning timing and quality of echocardiography and importance of SCS in detecting patients with coronary undiagnosed aneurysms.

Robotic voltammetry with carbon nanotube-based sensors: a superb blend for convenient high-quality antimicrobial trace analysis.

A new automated pharmacoanalytical technique for convenient quantification of redox-active antibiotics has been established by combining the benefits of a carbon nanotube (CNT) sensor modification with electrocatalytic activity for analyte detection with the merits of a robotic electrochemical device that is capable of sequential nonmanual sample measurements in 24-well microtiter plates. Norfloxacin (NFX) and ciprofloxacin (CFX), two standard fluoroquinolone antibiotics, were used in automated calibration measurements by differential pulse voltammetry (DPV) and accomplished were linear ranges of 1–10 μM and 2–100 μM for NFX and CFX, respectively. The lowest detectable levels were estimated to be 0.3±0.1 μM (n=7) for NFX and 1.6±0.1 μM (n=7) for CFX. In standard solutions or tablet samples of known content, both analytes could be quantified with the robotic DPV microtiter plate assay, with recoveries within ±4% of 100%. And recoveries were as good when NFX was evaluated in human serum samples with added NFX. The use of simple instrumentation, convenience in execution, and high effectiveness in analyte quantitation suggest the merger between automated microtiter plate voltammetry and CNT-supported electrochemical drug detection as a novel methodology for antibiotic testing in pharmaceutical and clinical research and quality control laboratories.

The design and implementation of regional creatine kinase/lactate dehydrogenase detection standardization

Objective To design and implement the standardization scheme of creatine kinase(CK)/lactate dehydrogenase(LDH) detection based on the present situation of clinical laboratory in Jiaxing, and attempt to reduce the imprecision and bias of the results in different clinical laboratories, obtain the traceable results. Methods According to the requirements of traceability in clinical laboratory, the CK/LDH standardization scheme was explored in Jiaxing from 2012, October to 2013, February,CK/LDH national reference material GBW09167, GBW09168 and serum pool were as samples for accuracy verification and impression in 33 local hospitals; then the reference materials GBW(E)03061 was as calibrator, while the GBWE03060 was performed as calibration verification material during the tests, the SOP for calibration made by the clinical quality control center was operated in calibration; as a result a scientific, practical standard scheme was developed. Results The equipment of clinical labrotories in Jiaxing are all imported, the laboratory management is well.However the bias of CK is -7%-12% and the bias of LDH is above -22%-15%. And then the standardization scheme was implemented in 6 Laboratories in which CV was less than 2%, and high-quality data of 5 laboratories are as follows:imprecision of CK and LDH in different labs were reduced from 4.95%-6.55% to 1.81%-2.33% and 5.75%-11.68% to 1.39%-1.80% individually， bias for CK is reduced from -0.84 %-6.23% to -0.15%-2.44% ; while in lactate dehydrogenase test, the bias is decreased from -10.18%-0.34% to -3.07%-0.58% . Conclusion Using the commutable and traceable reference material as calibrator, strengening the laboratory management such as making a calibration SOP will be a effective methods to realize the standardization in measurement.（Chin J Lab Med，2014,37：947-950） Key words: Creatine kinase; Lactate dehydrogenases; Reference standards; Laboratories, hospital; Research design

Immobilisation strategies for construction of tyrosinase-based biosensors

Analytical application of immobilised enzyme system is mainly in biosensors. Meeting the demand for practical, cost effective and portable analytical devices, enzyme based biosensors have enormous potential applications in clinical diagnosis, environmental monitoring, bioprocess and food quality control, biomedical and pharmaceutical analysis. Tyrosinase is one of the most extensively studied enzymes for applications in enzyme based biosensors. Since immobilisation of enzyme is crucial for the construction and performance of biosensors, the present overview focuses on functional materials for the development of tyrosinase based biosensors. A short description of how electrochemical sensors are more advantageous for the detection of phenolic compounds is given, followed by sources of tyrosinase and electrode material used in tyrosinase based sensors. Various approaches to biosensor construction with respect to tyrosinase immobilisation, e.g. sol–gel techniques, self-assembled architectures, synthetic, conducting and biopolymers, nanomaterials, are also presented. The review intends to highlight immobilisation strategies in developing tyrosinase based biosensors.

Detection of mixed infection level of Plasmodium falciparum and Plasmodium vivax by SYBR Green I-based real-time PCR in North Gondar, north-west Ethiopia.

BackgroundMalaria is caused by five Plasmodium species and transmitted by anopheline mosquitoes. It occurs in single and mixed infections. Mixed infection easily leads to misdiagnosis. Accurate detection of malaria species is vital. Therefore, the study was conducted to determine the level of mixed infection and misdiagnosis of malaria species in the study area using SYBR Green I-based real time PCR.MethodsThe study was conducted in seven health centres from North Gondar, north-west Ethiopia. The data of all febrile patients, who attended the outpatient department for malaria diagnosis, from October to December 2013, was recorded. Dried blood spots were prepared from 168 positive samples for molecular re-evaluation. Parasite DNA was extracted using a commercial kit and Plasmodium species were re-evaluated with SYBR Green I-based real time PCR to detect mixed infections and misdiagnosed mono-infections.ResultsAmong 7343 patients who were diagnosed for malaria in six study sites within the second quarter of the Ethiopian fiscal year (2013) 1802 (24.54%) were positive for malaria parasite. Out of this, 1,216 (67.48%) Plasmodium falciparum, 553 (30.68%) Plasmodium vivax and 33 (1.8%) mixed infections of both species were recorded. The result showed high prevalence of P. falciparum and P. vivax, but very low prevalence of mixed infections. Among 168 samples collected on dried blood spot 7 (4.17%) were P. vivax, 158 (94.05%) were P. falciparum and 3 (1.80%) were mixed infections of both species. After re-evaluation 10 (5.95%) P. vivax, 112 (66.67%) P. falciparum, 21 (12.50%) P. falciparum + P. vivax mixed infection, and 17 (10.12%) Plasmodium ovale positive rate was recorded. The re-evaluation showed high level of mixed infection, and misdiagnosis of P. ovale and P. vivax.ConclusionsThe result shows that P. falciparum prevalence is higher than P. vivax in the study area. The results, obtained from SYBR Green I-based real time PCR, indicated that the diagnosis efficiency of microscopy is very low for species-specific and mixed infection detection. Therefore, real time PCR-based species diagnosis should be applied for clinical diagnosis and quality control purposes in order to prevent the advent of drug resistant strains due to misdiagnosis and mistreatment.

SU‐E‐CAMPUS‐J‐02: Implementation of Routine Clinical Daily Dose Evaluation for Patient Specific Quality Control

Purpose:The use of deformable registration and dose assessment in prospective clinical trials and routine patient quality control has been limited, largely due to lack of integration of the tools into standard clinical practice and decision support tools. A clinical workflow has been developed and implemented in a standard planning system using in room image.Methods:A patient‐specific quality control procedure has been initiated to ensure safe and accurate treatment delivery and develop decision making guidelines for future adaptation scenarios. Deformable registration, contour propagation, and dose calculation was performed in a clinical system (Varian, Eclipse v11). Twenty head and neck patients diagnosed with base of tongue cancer and treated with volumetric modulated arc therapy (VMAT) following daily kV‐CBCT were evaluated. The planning CT was deformed to the daily CBCT to propagate the planning contours. Daily dose was calculated on the CBCT using a density calibration table and evaluated using the mapped contours. Deviations in the normal tissues were evaluated including the mean dose to the superior constrictors, left and right parotid glands (LPG, RPG), and left and right submandibular glands (LSG, RSG). The CTV D95 was also evaluated.Results:Deformable registration and contour propagation was qualitatively evaluated and deemed acceptable for each fraction. The average (SD) daily fluctuation (planned‐daily) in mean dose to the superior constrictor, LPG, RPG, LSG, and RSG was −3.0(6.0), 1.4(8.8), −1.1(10.7), 1.0(5.4), −2.0(8.5) cGy, respectively. The average (SD) daily fluctuation in D95 for the CTV was 3.7(3.8) cGy.Conclusion:Daily dose assessment is feasible in a clinically available system. Data to guide adaptive decision making guidelines have been suggested, but require evaluation on additional patients for validity, which is ongoing. Dose accumulation, which is necessary for optimizing adaptive replanning, is needed within the clinical system to fully take advantage of this data.

SU‐E‐J‐129: A Strategy to Consolidate the Image Database of a VERO Unit Into a Radiotherapy Management System

Purpose:To present a strategy to integrate the imaging database of a VERO unit with a treatment management system (TMS) to improve clinical workflow and consolidate image data to facilitate clinical quality control and documentation.Methods:A VERO unit is equipped with both kV and MV imaging capabilities for IGRT treatments. It has its own imaging database behind a firewall. It has been a challenge to transfer images on this unit to a TMS in a radiation therapy clinic so that registered images can be reviewed remotely with an approval or rejection record. In this study, a software system, iPump‐VERO, was developed to connect VERO and a TMS in our clinic. The patient database folder on the VERO unit was mapped to a read‐only folder on a file server outside VERO firewall. The application runs on a regular computer with the read access to the patient database folder. It finds the latest registered images and fuses them in one of six predefined patterns before sends them via DICOM connection to the TMS. The residual image registration errors will be overlaid on the fused image to facilitate image review.Results:The fused images of either registered kV planar images or CBCT images are fully DICOM compatible. A sentinel module is built to sense new registered images with negligible computing resources from the VERO ExacTrac imaging computer. It takes a few seconds to fuse registered images and send them to the TMS. The whole process is automated without any human intervention.Conclusion:Transferring images in DICOM connection is the easiest way to consolidate images of various sources in your TMS. Technically the attending does not have to go to the VERO treatment console to review image registration prior delivery. It is a useful tool for a busy clinic with a VERO unit.

An angle-dependent estimation of CT x-ray spectrum from rotational transmission measurements.

Computed tomography (CT) performance as well as dose and image quality is directly affected by the x-ray spectrum. However, the current assessment approaches of the CT x-ray spectrum require costly measurement equipment and complicated operational procedures, and are often limited to the spectrum corresponding to the center of rotation. In order to address these limitations, the authors propose an angle-dependent estimation technique, where the incident spectra across a wide range of angular trajectories can be estimated accurately with only a single phantom and a single axial scan in the absence of the knowledge of the bowtie filter. The proposed technique uses a uniform cylindrical phantom, made of ultra-high-molecular-weight polyethylene and positioned in an off-centered geometry. The projection data acquired with an axial scan have a twofold purpose. First, they serve as a reflection of the transmission measurements across different angular trajectories. Second, they are used to reconstruct the cross sectional image of the phantom, which is then utilized to compute the intersection length of each transmission measurement. With each CT detector element recording a range of transmission measurements for a single angular trajectory, the spectrum is estimated for that trajectory. A data conditioning procedure is used to combine information from hundreds of collected transmission measurements to accelerate the estimation speed, to reduce noise, and to improve estimation stability. The proposed spectral estimation technique was validated experimentally using a clinical scanner (Somatom Definition Flash, Siemens Healthcare, Germany) with spectra provided by the manufacturer serving as the comparison standard. Results obtained with the proposed technique were compared against those obtained from a second conventional transmission measurement technique with two materials (i.e., Cu and Al). After validation, the proposed technique was applied to measure spectra from the clinical system across a range of angular trajectories [-15°, 15°] and spectrum settings (80, 100, 120, 140 kVp). At 140 kVp, the proposed technique was comparable to the conventional technique in terms of the mean energy difference (MED, -0.29 keV) and the normalized root mean square difference (NRMSD, 0.84%) from the comparison standard compared to 0.64 keV and 1.56%, respectively, with the conventional technique. The average absolute MEDs and NRMSDs across kVp settings and angular trajectories were less than 0.61 keV and 3.41%, respectively, which indicates a high level of estimation accuracy and stability. An angle-dependent estimation technique of CT x-ray spectra from rotational transmission measurements was proposed. Compared with the conventional technique, the proposed method simplifies the measurement procedures and enables incident spectral estimation for a wide range of angular trajectories. The proposed technique is suitable for rigorous research objectives as well as routine clinical quality control procedures.