Clinical Quality Assurance Research Articles

Evaluation of an aSi‐EPID with flattening filter free beams: Applicability to the GLAaS algorithm for portal dosimetry and first experience for pretreatment QA of RapidArc

To demonstrate the feasibility of portal dosimetry with an amorphous silicon mega voltage imager for flattening filter free (FFF) photon beams by means of the GLAaS methodology and to validate it for pretreatment quality assurance of volumetric modulated arc therapy (RapidArc). The GLAaS algorithm, developed for flattened beams, was applied to FFF beams of nominal energy of 6 and 10 MV generated by a Varian TrueBeam (TB). The amorphous silicon electronic portal imager [named mega voltage imager (MVI) on TB] was used to generate integrated images that were converted into matrices of absorbed dose to water. To enable GLAaS use under the increased dose-per-pulse and dose-rate conditions of the FFF beams, new operational source-detector-distance (SDD) was identified to solve detector saturation issues. Empirical corrections were defined to account for the shape of the profiles of the FFF beams to expand the original methodology of beam profile and arm backscattering correction. GLAaS for FFF beams was validated on pretreatment verification of RapidArc plans for three different TB linacs. In addition, the first pretreatment results from clinical experience on 74 arcs were reported in terms of γ analysis. MVI saturates at 100 cm SDD for FFF beams but this can be avoided if images are acquired at 150 cm for all nominal dose rates of FFF beams. Rotational stability of the gantry-imager system was tested and resulted in a minimal apparent imager displacement during rotation of 0.2 ± 0.2 mm at SDD = 150 cm. The accuracy of this approach was tested with three different Varian TrueBeam linacs from different institutes. Data were stratified per energy and machine and showed no dependence with beam quality and MLC model. The results from clinical pretreatment quality assurance, provided a gamma agreement index (GAI) in the field area for six and ten FFF beams of (99.8 ± 0.3)% and (99.5 ± 0.6)% with distance to agreement and dose difference criteria set to 3 mm/3% with 2 mm/2% thresholds, GAI resulted (95.7.0 ± 2.3)% and (97.2 ± 2.1)%. The GLAaS methodology, introduced in clinical practice for conventional flattened photon beams for machine, IMRT, and RapidArc quality assurance, was successfully adapted for FFF beams of Varian TrueBeam Linac. The detector saturation effects could be eliminated if the portal images acquired at 150 cm for all nominal dose rates of FFF beams.

Clinical Pharmacology Quality Assurance Program

Among National Institutes of Health HIV Research Networks conducting multicenter trials, samples from protocols that span several years are analyzed at multiple clinical pharmacology laboratories (CPLs) for multiple antiretrovirals. Drug assay data are, in turn, entered into study-specific data sets that are used for pharmacokinetic analyses, merged to conduct cross-protocol pharmacokinetic analysis, and integrated with pharmacogenomics research to investigate pharmacokinetic-pharmacogenetic associations. The CPLs participate in a semiannual proficiency testing (PT) program implemented by the Clinical Pharmacology Quality Assurance program. Using results from multiple PT rounds, longitudinal analyses of recovery are reflective of accuracy and precision within/across laboratories. The objectives of this longitudinal analysis of PT across multiple CPLs were to develop and test statistical models that longitudinally: (1) assess the precision and accuracy of concentrations reported by individual CPLs and (2) determine factors associated with round-specific and long-term assay accuracy, precision, and bias using a new regression model. A measure of absolute recovery is explored as a simultaneous measure of accuracy and precision. Overall, the analysis outcomes assured 97% accuracy (±20% of the final target concentration of all (21) drug concentration results reported for clinical trial samples by multiple CPLs). Using the Clinical Laboratory Improvement Act acceptance of meeting criteria for ≥2/3 consecutive rounds, all 10 laboratories that participated in 3 or more rounds per analyte maintained Clinical Laboratory Improvement Act proficiency. Significant associations were present between magnitude of error and CPL (Kruskal-Wallis P < 0.001) and antiretroviral (Kruskal-Wallis P < 0.001).

A novel technique for VMAT QA with EPID in cine mode on a Varian TrueBeam linac

Volumetric modulated arc therapy (VMAT) is a relatively new treatment modality for dynamic photon radiation therapy. Pre-treatment quality assurance (QA) is necessary and many efforts have been made to apply electronic portal imaging device (EPID)-based IMRT QA methods to VMAT. It is important to verify the gantry rotation speed during delivery as this is a new variable that is also modulated in VMAT. In this paper, we present a new technique to perform VMAT QA using an EPID. The method utilizes EPID cine mode and was tested on Varian TrueBeam in research mode. The cine images were acquired during delivery and converted to dose matrices after profile correction and dose calibration. A sub-arc corresponding to each cine image was extracted from the original plan and its portal image prediction was calculated. Several analyses were performed including 3D γ analysis (2D images + gantry angle axis), 2D γ analysis, and other statistical analyses. The method was applied to 21 VMAT photon plans of 3 photon energies. The accuracy of the cine image information was investigated. Furthermore, this method's sensitivity to machine delivery errors was studied. The pass rate (92.8 ± 1.4%) for 3D γ analysis was comparable to those from Delta4 system (99.9 ± 0.1%) under similar criteria (3%, 3 mm, 5% threshold and 2° angle to agreement) at 6 MV. The recorded gantry angle and start/stop MUs were found to have sufficient accuracy for clinical QA. Machine delivery errors can be detected through combined analyses of 3D γ, gantry angle, and percentage dose difference. In summary, we have developed and validated a QA technique that can simultaneously verify the gantry angle and delivered MLC fluence for VMAT treatment.This technique is efficient and its accuracy is comparable to other QA methods.

PRIMO: A graphical environment for the Monte Carlo simulation of Varian and Elekta linacs

The accurate Monte Carlo simulation of a linac requires a detailed description of its geometry and the application of elaborate variance-reduction techniques for radiation transport. Both tasks entail a substantial coding effort and demand advanced knowledge of the intricacies of the Monte Carlo system being used. PRIMO, a new Monte Carlo system that allows the effortless simulation of most Varian and Elekta linacs, including their multileaf collimators and electron applicators, is introduced. PRIMO combines (1) accurate physics from the PENELOPE code, (2) dedicated variance-reduction techniques that significantly reduce the computation time, and (3) a user-friendly graphical interface with tools for the analysis of the generated data. PRIMO can tally dose distributions in phantoms and computerized tomographies, handle phase-space files in IAEA format, and import structures (planning target volumes, organs at risk) in the DICOM RT-STRUCT standard. A prostate treatment, conformed with a high definition Millenium multileaf collimator (MLC 120HD) from a Varian Clinac 2100 C/D, is presented as an example. The computation of the dose distribution in 1.86×3.00×1.86 mm3 voxels with an average 2% standard statistical uncertainty, performed on an eight-core Intel Xeon at 2.67 GHz, took 1.8 h-excluding the patient-independent part of the linac, which required 3.8 h but it is simulated only once. PRIMO is a self-contained user-friendly system that facilitates the Monte Carlo simulation of dose distributions produced by most currently available linacs. This opens the door for routine use of Monte Carlo in clinical research and quality assurance purposes. It is free software that can be downloaded from http://www.primoproject.net.

Audit of the Informed Consent Process as a Part of a Clinical Research Quality Assurance Program

Audits of the informed consent process are a key element of a clinical research quality assurance program. A systematic approach to such audits has not been described in the literature. In this paper we describe two components of the audit. The first is the audit of the informed consent document to verify adherence with federal regulations. The second component is comprised of the audit of the informed consent conference, with emphasis on a real time review of the appropriate communication of the key elements of the informed consent. Quality measures may include preparation of an informed consent history log, notes to accompany the informed consent, the use of an informed consent feedback tool, and the use of institutional surveys to assess comprehension of the informed consent process.

Delta three-dimensional semiconductor array verification for intensity modulated planning of helical tomotherapy

Objective To investigate the feasibility of dose verification of intensity modulated planning of helical tomotherapy (HT) using three-dimensional semiconductor array (Delta4) and find a more time-consuming and accurate method to validate the delivery dose.Methods Delta4 detector array was used to verify the HT plan dose distribution of 10 patients.The precise setup of detector array was guided and registered by MVCT imaging.After the implementation of delivery,the measured dose distributions on the corresponding planes were compared with those calculated by the treatment planning system (TPS).According to the different acceptance criteria combination of dose difference or distance to agreement at different threshold level including 3％/2 mm,3％/3 mm,3％/4 mm,3％/5 mm at TH5,TH10,TH20,TH30,TH70,TH90,the γ analysis method was utilized to evaluate the dose verification.Results The dose distribution measured by the Delta4 was well consistent with that calculated by the TPS.The mean γpassing rates were all above 94.89％.Conclusions Delta4 detector array can get satisfying results when used in HT plan dose verification and is a viable tool to replace traditional film dosimetry system in clinical quality assurance work. Key words: Dose verification; Three-dimensional detector array; Helical tomotherapy

Dosimetry for audit and clinical trials: challenges and requirements

Many important dosimetry audit networks for radiotherapy have their roots in clinical trial quality assurance (QA). In both scenarios it is essential to test two issues: does the treatment plan conform with the clinical requirements and is the plan a reasonable representation of what is actually delivered to a patient throughout their course of treatment. Part of a sound quality program would be an external audit of these issues with verification of the equivalence of plan and treatment typically referred to as a dosimetry audit. The increasing complexity of radiotherapy planning and delivery makes audits challenging. While verification of absolute dose delivered at a reference point was the standard of external dosimetry audits two decades ago this is often deemed inadequate for verification of treatment approaches such as Intensity Modulated Radiation Therapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT). As such, most dosimetry audit networks have successfully introduced more complex tests of dose delivery using anthropomorphic phantoms that can be imaged, planned and treated as a patient would. The new challenge is to adapt this approach to ever more diversified radiotherapy procedures with image guided/adaptive radiotherapy, motion management and brachytherapy being the focus of current research.

A semi-automated tool for treatment plan-quality evaluation and clinical trial quality assurance

The goal of this work is to develop a plan-quality evaluation program for clinical routine and multi-institutional clinical trials so that the overall evaluation efficiency is improved. In multi-institutional clinical trials evaluating the plan quality is a time-consuming and labor-intensive process. In this note, we present a semi-automated plan-quality evaluation program which combines MIMVista, Java/MATLAB, and extensible markup language (XML). More specifically, MIMVista is used for data visualization; Java and its powerful function library are implemented for calculating dosimetry parameters; and to improve the clarity of the index definitions, XML is applied. The accuracy and the efficiency of the program were evaluated by comparing the results of the program with the manually recorded results in two RTOG trials. A slight difference of about 0.2% in volume or 0.6 Gy in dose between the semi-automated program and manual recording was observed. According to the criteria of indices, there are minimal differences between the two methods. The evaluation time is reduced from 10–20 min to 2 min by applying the semi-automated plan-quality evaluation program.

Development and validation of automatic tools for interactive recurrence analysis in radiation therapy: optimization of treatment algorithms for locally advanced pancreatic cancer

BackgroundIn radiation oncology recurrence analysis is an important part in the evaluation process and clinical quality assurance of treatment concepts. With the example of 9 patients with locally advanced pancreatic cancer we developed and validated interactive analysis tools to support the evaluation workflow.MethodsAfter an automatic registration of the radiation planning CTs with the follow-up images, the recurrence volumes are segmented manually. Based on these volumes the DVH (dose volume histogram) statistic is calculated, followed by the determination of the dose applied to the region of recurrence and the distance between the boost and recurrence volume. We calculated the percentage of the recurrence volume within the 80%-isodose volume and compared it to the location of the recurrence within the boost volume, boost + 1 cm, boost + 1.5 cm and boost + 2 cm volumes.ResultsRecurrence analysis of 9 patients demonstrated that all recurrences except one occurred within the defined GTV/boost volume; one recurrence developed beyond the field border/outfield. With the defined distance volumes in relation to the recurrences, we could show that 7 recurrent lesions were within the 2 cm radius of the primary tumor. Two large recurrences extended beyond the 2 cm, however, this might be due to very rapid growth and/or late detection of the tumor progression.ConclusionThe main goal of using automatic analysis tools is to reduce time and effort conducting clinical analyses. We showed a first approach and use of a semi-automated workflow for recurrence analysis, which will be continuously optimized. In conclusion, despite the limitations of the automatic calculations we contributed to in-house optimization of subsequent study concepts based on an improved and validated target volume definition.

MO‐A‐108‐01: The Impact of Intensity Modulated Proton Therapy On Proton Therapy?

One of the major controversies surrounding proton therapy is that despite the high cost of proton therapy relative to conventional x‐ray radiotherapy, the clinical benefit of proton therapy has not been clearly demonstrated in the literature. The majority of clinical studies comparing proton and photon therapy have compared passive scattering proton therapy (PSPT) with intensity‐modulated radiation therapy (IMRT). However, the delivery of proton therapy, while predominantly in the form of PSPT, is likely to be superseded by intensity modulated proton therapy (IMPT). Improvement in dose distribution by IMPT in a representative series of patients compared to IMRT has been reported. It appears that IMPT will have the opportunity to justify adopting the proton therapy in the routine care for majority disease.This session will begin with a short introduction explaining the current state of the art for IMPT. This introduction will be followed by four presentations. The first presentation will cover the efficacy of proton therapy for prostate cancer from a clinician's point of view. The second presentation will provide more detail on the current state of the art for proton therapy, introduce future research directions for IMPT technology, and address the impact of the research on proton therapy. The third presentation will cover the clinical and operational reasoning behind an all‐scanning‐beam facility and the expertise needed to build such a facility. In the fourth presentation, a physicist and a physician will present their center's experience with implementing IMPT techniques for lung, head and neck, and central nervous system tumors and present relevant clinical protocols and data.Learning Objectives:1. Describe the current machine delivery systems and treatment planning, quality assurance, and dose verification techniques for IMPT.2. Explain the clinical efficacy and cost‐effectiveness of proton therapy.3. Differentiate the capabilities of IMPT from those of PSPT and IMRT and explain how the unique capabilities of IMPT improve the clinical efficacy and cost‐effectiveness of proton therapy.4. Provide examples of working clinical protocols, workflow, and quality assurance procedures for the use of IMPT in routine patient care.

WE‐G‐141‐01: The Imaging and Radiation Oncology Core (IROC) Group: A Proposed New Clinical Trial Quality Assurance Organization

Purpose: The NCI is implementing the new National Clinical Trial Network (NCTN) Program in 2014 reducing the number of existing study groups from ten to five. The NCTN Program also requires a new combined Imaging and Radiation Oncology Core (IROC) service to provide a uniform QA program. Methods: The six existing clinical trial QA centers, Radiological Physics Center, Quality Assurance Review Center, RTOG QA Center, Image Guided Therapy Center, ACRIN Core Lab and the CALGB Imaging Core Lab have combined to form IROC. The interdependencies between diagnostic imaging and radiation therapy (RT) will be synergized in IROC eliminating duplication of services within the network and optimizing efficient and effective workflows. A major strength of this new organization will be the development of consistent standard operating procedures for all imaging and RT aspects of the NCTN as well as to facilitate a seamless flow of imaging and RT datasets across the network. Results: IROC, administered though the American College of Radiology will provide the scientific and technical expertise in both diagnostic imaging and RT to the entire NCTN Program capitalizing on existing infrastructure and expertise at QA centers currently providing services to the NCI Cooperative Groups. IROC's organizational structure will allow the delivery of a broad array of imaging and RT QA services including Site Qualification; Trial Design Support; Credentialing; Data Management and Case Review. IROC will work closely with the leadership of each Network Group and NCI to assure them that imaging and RT data used by the Groups for protocol analysis are accurate. Conclusion: The proposed IROC Group has hundreds of collective years of experience conducting clinical trial QA and fully understands the QA needs/dataflow requirements of clinical trials to maintain the highest quality clinical trial data that will not obscure the outcomes of clinical trials. This work was supported by PHS grants CA10953, CA21661, CA029511 and CA081647 awarded by NCI, DHHS.

SU‐E‐T‐234: An Automated Tool for Treatment Plan Quality Evaluation and Clinical Trial Quality Assurance

Purpose: Develop an automated plan‐quality evaluation program for multi‐institutional clinical trials to improve case review efficiency. This program is generally applicable to routine clinical process to raise practice quality level. Methods: In this study, we developed an automated plan‐quality evaluation program which combines MIMVista, Java/MATLAB, and extensible markup language (XML). More specifically, MIMVista is used for data visualization; Java and its powerful function library are implemented for calculating dosimetry parameters; and to improve the clarity of the index definitions, XML is applied. The accuracy and the efficiency of the program were evaluated by comparing the results of the program with the manually recorded results in two RTOG trials. Results: A slight difference of about 0.2% in volume or 0.6Gy in dose between the automated program and manual recording was observed. According to the criteria of indices, there was no significant difference between the two methods. The evaluation time was reduced from 10–20 minutes to 2 minutes by applying the automated plan‐quality evaluation program. Conclusion: Quality review efficiency was much improved by using this automated plan‐quality evaluation tool. Accuracy was also improved as human error was eliminated. This tool will be made freely available to benefit general clinical practice.

Prostate radiotherapy clinical trial quality assurance: How real should real time review be? (A TROG-OCOG Intergroup Project)

Background and purposeReview of plans early in treatment offers the potential to reduce the chance of sub-optimal treatment delivery. We compare the use of real time reviews (RTR) either before randomization (pre-rand 3D RTR) or following randomization (post-rand 2D RTR). Materials and methodsPROFIT is an international randomised trial for men with prostate cancer which had credentialing via multiple dummy runs. In Australia, but not Canada, all plans were submitted for pre-rand 3D RTR using 3D software, and resubmission was requested if significant protocol deviations (PD) were seen. All plans from Canada and Australia then underwent post-rand 2D RTR using a 2D assessment. ResultsFor 147 Australian patients, pre-rand 3D RTR was fast (median 1day, 95% range 0–4days). 51 minor and 5 major PD were observed and 15 of the 147 cases (10%) required resubmission. Of the 5 major PD, 4 were remedied on resubmission and 1 was withdrawn from study. For the post-rand 2D RTR, reports from 147 Australian cases and 193 Canadian cases were reviewed. No major PD were reported from Australian cases, but 3 were seen in Canadian cases (0% versus 1.5%; p=0.26). There was also no difference in the rate of minor PD (14.3% versus 15.3%; p=NS). ConclusionsIn a study using relatively simple treatment volumes after comprehensive credentialing, pre-rand 3D RTR offers only modest benefits compared with post-rand 2D RTR. In the future the intensity of RTR may need to vary according to protocol and site specific factors.

SU‐E‐I‐56: An Overview of a CT Protocol Optimization Process at a Major University Hospital Medical Center; Including Details On Physics Support, IT Support, and a Radiologist Based Quality Assurance Program

Purpose: Modern CT departments with multiple scanner architectures can easily have hundreds of different protocols for different size patients and clinical requirements. Unless a systematic approach is taken to the optimization and quality assurance of these protocols, care to the patient in the form of image quality, dose, and clinical usability of the CT exams can be compromised. The purpose of this study is to present the model that has been put into a operational form after being organically developed by the medical physicists, radiologists, IT staff, and CT technologists at our over the last several years. Methods: The process of CT protocol formation will be covered including: assessment of the CT scanner technology by the medical physicist, clinical protocol requirements determined by clinicians, optimization of protocols parameters by the medical physicist, final review of the protocols by the entire protocol optimization team, and the subsequent clinical application of the protocols. After implementation, a clinical quality assurance program enables radiologists to score CT exams while reading them on a standard PACS workstation and concurrently the medical physics team monitors the radiation dose (patient size specific) and reviews image quality concerns made by radiologists. The IT infrastructure for this QA assurance process will also be presented. Results: We have successfully gone through several iterations of the CT protocol optimization procedure presented in this study at our institution. The incorporation of new technologies was reviewed and fit into our protocol optimization process as well. The operational procedures defined in this study have greatly increased the efficiency with which we manage and optimize protocols at our institution. Conclusion: CT protocol optimization is an ongoing process; constant monitoring of patient dose and image quality, incorporation of new scanner technologies, and changing clinical requirements all necessitate an organized approach to CT protocols optimization. Equipment grant from GE healthcare.

SU-E-T-575: Independent Verification of VMAT Treatment Plans Using a DICOM-RT Framework

Purpose: To compare volumetric modulated arc therapy (VMAT) treatment plans calculated with Eclipse 10 (RapidArc, Varian Medical Systems) and Pinnacle 9.2 (SmartArc, Philips Healthcare) to those computed with an independent verification system utilizing a DICOM‐RT framework Mobius3D (M3D 1.1, Mobius Medical Systems, LP). Methods: Mobius3D (M3D) utilizes standardized machine data, supplemented by custom scaled measured depth dose curves, output factors and off‐axis ratios, to create institution specific beam models as an independent dose validation check. A randomly selected set of clinical radiotherapy plans generated by two treatment planning systems (TPS) consisting of 26 RapidArc prostate plans and 29 SmartArc head and neck plans were exported to M3D. The requisite DICOM‐RT files sent to M3D included CT images, contoured structure sets, RT plan and RT dose. This data was used to recalculate 3D dose distributions using a collapsed cone algorithm in M3D. Dose distributions were compared to those calculated by the TPS 3D dose using a 3D gamma analysis with 3% global dose difference and 3 mm isodose point distance criteria. Additionally, TPS's and M3D's target coverage and regions of interests sparing were compared by calculating the mean dose percent difference for each structure. DVH from each system were also compared. Results: On average, M3D plans showed excellent 3D gamma passing rates agreement of (99.1%±1.1%) and (95.7%±2.2%) relative to RapidArc and SmartArc plans, respectively. Similarly, the M3D recalculated and RapidArc and SmartArc calculated mean target dose percent differences demonstrated small differences of (−0.3%±1.2%) and (− 1.2%±0.9%), respectively. Conclusion: Mobius3D enables a paradigm shift in clinical quality assurance practice by moving beyond single point dose and MU verification to a full 3D treatment plan QA check. The VMAT results obtained utilizing fast and fully automated M3D software showed that M3D is suitable for an independent check of RapidArc and SmartArc plans.

WE-G-108-08: A Novel Technique for VMAT QA with EPID in Cine Mode On Varian TrueBeam

Purpose: Volumetric modulated arc therapy (VMAT) is a relatively new treatment modality for dynamic photon radiation therapy. Pre‐treatment quality assurance (QA) is necessary and many efforts have been taken to apply electronic portal imaging device (EPID) based IMRT QA methods to VMAT. It is important to verify the gantry angles during delivery as this is new variable that is also modulated in VMAT. The purpose of this study is to develop and validate a new technique that is accurate and efficient to perform VMAT QA using EPID. Methods: The method utilized EPID cine mode and was tested on Varian TrueBeam in research mode. The cine images were acquired during delivery and converted to dose matrices after profile correction and dose calibration. Sub‐arc corresponding to each cine image was extracted from the original plan and its portal image prediction was calculated. Several analyses were performed including 3D γ analysis (2D images plus gantry angle axis), 2D γ analysis, and other statistical analyses. The method was applied to 21 VMAT beams of 6MV photons and the accuracy of cine image information was investigated. Furthermore, this method's sensitivity to machine delivery errors was studied. Results: The pass rate (97.8±1.1%) for 3D γ analysis was comparable to that from Delta4 (99.9±0.1%) under similar criteria (3%, 3mm, 5% threshold and 3°angle to agreement). The recorded gantry angle and start/stop MUs were found to have sufficient accuracy for clinical QA. Machine delivery errors can be detected through combined analyses of 3D γ index, gantry angle, and percentage dose difference. Conclusion: We have developed and validated a QA technique that can simultaneously verify the gantry angle and delivered MLC fluence for VMAT treatment. The method is efficient and its accuracy is comparable to other methods. B Liu's work was supported by the Chinese Scholarship Council.

Quantitative assessment of the accuracy of dose calculation using pencil beam and Monte Carlo algorithms and requirements for clinical quality assurance

To compare the doses calculated using the BrainLAB pencil beam (PB) and Monte Carlo (MC) algorithms for tumors located in various sites including the lung and evaluate quality assurance procedures required for the verification of the accuracy of dose calculation. The dose-calculation accuracy of PB and MC was also assessed quantitatively with measurement using ionization chamber and Gafchromic films placed in solid water and heterogeneous phantoms. The dose was calculated using PB convolution and MC algorithms in the iPlan treatment planning system from BrainLAB. The dose calculation was performed on the patient's computed tomography images with lesions in various treatment sites including 5 lungs, 5 prostates, 4 brains, 2 head and necks, and 2 paraspinal tissues. A combination of conventional, conformal, and intensity-modulated radiation therapy plans was used in dose calculation. The leaf sequence from intensity-modulated radiation therapy plans or beam shapes from conformal plans and monitor units and other planning parameters calculated by the PB were identical for calculating dose with MC. Heterogeneity correction was considered in both PB and MC dose calculations. Dose-volume parameters such as V95 (volume covered by 95% of prescription dose), dose distributions, and gamma analysis were used to evaluate the calculated dose by PB and MC. The measured doses by ionization chamber and EBT GAFCHROMIC film in solid water and heterogeneous phantoms were used to quantitatively asses the accuracy of dose calculated by PB and MC. The dose-volume histograms and dose distributions calculated by PB and MC in the brain, prostate, paraspinal, and head and neck were in good agreement with one another (within 5%) and provided acceptable planning target volume coverage. However, dose distributions of the patients with lung cancer had large discrepancies. For a plan optimized with PB, the dose coverage was shown as clinically acceptable, whereas in reality, the MC showed a systematic lack of dose coverage. The dose calculated by PB for lung tumors was overestimated by up to 40%. An interesting feature that was observed is that despite large discrepancies in dose-volume histogram coverage of the planning target volume between PB and MC, the point doses at the isocenter (center of the lesions) calculated by both algorithms were within 7% even for lung cases. The dose distributions measured with EBT GAFCHROMIC films in heterogeneous phantoms showed large discrepancies of nearly 15% lower than PB at interfaces between heterogeneous media, where these lower doses measured by the film were in agreement with those by MC. The doses (V95) calculated by MC and PB agreed within 5% for treatment sites with small tissue heterogeneities such as the prostate, brain, head and neck, and paraspinal tumors. Considerable discrepancies, up to 40%, were observed in the dose-volume coverage between MC and PB in lung tumors, which may affect clinical outcomes. The discrepancies between MC and PB increased for 15MV compared with 6MV indicating the importance of implementation of accurate clinical treatment planning such as MC. The comparison of point doses is not representative of the discrepancies in dose coverage and might be misleading in evaluating the accuracy of dose calculation between PB and MC. Thus, the clinical quality assurance procedures required to verify the accuracy of dose calculation using PB and MC need to consider measurements of 2- and 3-dimensional dose distributions rather than a single point measurement using heterogeneous phantoms instead of homogenous water-equivalent phantoms.

Clinical Pharmacology Quality Assurance for HIV and Related Infectious Diseases Research

The global HIV epidemic continues to grow in certain regions while contracting in others, necessitating a broadened research agenda, including clinical pharmacology of tuberculosis, hepatitis, malaria, and immune activation/inflammation, underscoring the need for a coordinated quality assurance approach. A comprehensive program has been developed and implemented by the University at Buffalo HIV Clinical Pharmacology Quality Assurance and Quality Control Program, funded by the National Institutes of Health. Clinical Pharmacology & Therapeutics (2013); 93 6, 479-482. doi:10.1038/clpt.2013.62

An investigation into the use of MMCTP to tune accelerator source parameters and testing its clinical application

This paper presents an alternative method to tune Monte Carlo electron beam parameters to match measured data using a minimal set of variables in order to reduce the model setup time prior to clinical implementation of the model. Monte Carlo calculations provide the possibility of a powerful treatment planning verification technique. The nonstandardized and nonautomated process of tuning the required accelerator model is one of the reasons for delays in the clinical implementation of Monte Carlo techniques. This work aims to establish and verify an alternative tuning method that can be carried out in a minimal amount of time, allowing it to be easily implemented in a clinical setting by personnel with minimal experience with Monte Carlo methods. This tuned model can then be incorporated into the MMCTP system to allow the system to be used as a second dose calculation check for IMRT plans. The technique proposed was used to establish the primary electron beam parameters for accelerator models for the Varian Clinac 2100 6 MV photon beam using the BEAMnrc Monte Carlo system. The method is intended to provide a clear, direct, and efficient process for tuning an accelerator model using readily available clinical quality assurance data. The tuning provides a refined model, which agrees with measured dose profile curves within 1.5% outside the penumbra or 3 mm in the penumbra, for square fields with sides of 3 cm up to 30 cm. These models can then be employed as the basis for Monte Carlo recalculations of dose distributions, using the MMCTP system, for clinical treatment plans, providing an invaluable assessment tool. This was tested on six IMRT plans and compared to the measurements performed for the pretreatment QA process. These Monte Carlo values for the average dose to the chamber volume agreed with measurements to within 0.6%.PACS number: 87.55.km

Volitional Delay of Self-Reported Outcomes

Intraoperative awareness with explicit recall (AWR) is a self-reported outcome of interest in clinical practice, quality assurance initiatives, and clinical trials. Combining structured postoperative interviews with a preoperative description of AWR is assumed to ensure prompt patient disclosure. We describe a volitionally delayed reporting of AWR because of the perceived unimportance of nondistressing awareness experiences, despite preoperative education and 2 postoperative interviews. This delay had implications for a major randomized controlled trial on AWR. Volitionally delayed self-reported outcomes may affect statistical comparisons in clinical trials and quality assurance initiatives, and delay the treatment of subsequent sequelae in clinical practice. This limitation should be considered, even when using structured outcome assessment and preoperative education.