Use of his prostheses by a double upper limb amputee 6 years after amputation: From aesthetic to functional considerations, a case report.

BACKGROUND: Few studies have been published on the prosthetic management of bilateral upper limb amputees. Of particular interest is to study how a patient's use of his upper limb protheses had evolved over a 6-year period in the aim to decrease their rejection rate. CASE DESCRIPTION AND METHODS: Mr. D had undergone a bilateral upper limb amputation and had been fitted with 7 different prostheses in the past 6 years. Multiple validate instruments and analyses were then used to monitor the patient's fitting and choices. FINDINGS AND OUTCOMES: Initially, the left prosthesis was regarded as the dominant hand and the right one as the assistive power grip hand. However, the observational results showed that wearing only a left Greifer enabled the prosthetic user to perform the same tasks as with 2 prostheses. He has gained greater satisfaction and quality of life without losing his independence. CONCLUSION: The patient seemed to make a functional choice over his worrying about his physical appearance in favor of the efficiency of his prosthesis, which was essential for his everyday life, when he decided to wear only nonanthropomorphic prosthesis.

Incremental Detection of Severe Congenital Heart Disease by Fetal Echocardiography Following a Normal Second Trimester Ultrasound Scan in Québec, Canada.

BACKGROUND: The benefit of fetal echocardiograms (FE) to detect severe congenital heart diseases (SCHD) in the setting of a normal second-trimester ultrasound is unclear. We aimed to assess whether the increase in SCHD detection rates when FE are performed for risk factors in the setting of a normal ultrasound was clinically significant to justify the resources needed. METHODS: This is a multicenter, population-based, retrospective cohort study, including all singleton pregnancies and offspring in Quebec (Canada) between 2007 and 2015. Administrative health care data were linked with FE clinical data to gather information on prenatal diagnosis of CHD, indications for FE, outcomes of pregnancy and offspring, postnatal diagnosis of CHD, cardiac interventions, and causes of death. The difference between the sensitivity to detect SCHD with and without FE for risk factors was calculated using generalized estimating equations with a noninferiority margin of 5 percentage points. RESULTS: A total of 688 247 singleton pregnancies were included, of which 30 263 had at least one FE. There were 1564 SCHD, including 1071 that were detected prenatally (68.5%). There were 12 210 FE performed for risk factors in the setting of a normal second-trimester ultrasound, which led to the detection of 49 additional cases of SCHD over 8 years. FE referrals for risk factors increased sensitivity by 3.1 percentage points (95% CI, 2.3-4.0; P<0.0001 for noninferiority). CONCLUSIONS: In the setting of a normal second-trimester ultrasound, adding a FE for risk factors offered low incremental value to the detection rate of SCHD in singleton pregnancies. The current ratio of clinical gains versus the FE resources needed to screen for SCHD in singleton pregnancies with isolated risk factors does not seem favorable. Further studies should evaluate whether these resources could be better allocated to increase SCHD sensitivity at the ultrasound level, and to help decrease heterogeneity between regions, institutions and operators.

Is everyone invited to the discussion table? A bibliometric analysis COVID-19-related mental health literature.

Background: The COVID-19 pandemic has captured the mental health discussion worldwide. Examining countries' representation in this discussion could prove instrumental in identifying potential gaps in terms of ensuring a truly global conversation in times of global crisis. Methods: We collected mental health and COVID-19-related journal articles published in PubMed in 2020. We focused on the corresponding authors' countries of affiliation to explore countries' representation. We also examined these articles' academic impact and correlations with their corresponding authors' countries of affiliation. Additional journals and countries' indicators were collected from the Web of Science and World Bank websites, respectively. Data were analyzed using the IBM SPSS Statistics and the VOSviewer software. Results: In total, 3492 publications were analyzed. Based on the corresponding author, high-income countries produced 61.9% of these publications. Corresponding authors from Africa, Latin America and the Caribbean, and the Middle East combined accounted for 11.8% of the publications. Europe hosted corresponding authors with the most publications and citations, and corresponding authors from North America had the largest mean journal impact factor. Conclusions: The global scientific discussion during the COVID-19 pandemic saw an increased contribution of academics from developing countries. However, authors from high-income countries have continued to shape this discussion. It is imperative to ensure the active participation of low- and middle-income countries in setting up the global mental health research agenda, particularly in situations of global crisis, such as the ongoing pandemic.

Evaluating the tendencies of community practitioners who actively practice in child and adolescent psychiatry to diagnose and treat DSM-5 attenuated psychotic syndrome.

The detection of individuals at clinical ultra-high risk for psychosis (CHR-P) may be a key limiting step for early interventions, and there is some uncertainty regarding the true clinical reliability of the CHR-P states. The aim of this study was to explore how practitioners who were in the direct treatment of children with psychiatric disorders [child psychiatry specialists/trainees (n = 227, n = 131), adult psychiatrists (n = 27), and child neurologists (n = 2)] perceive the DSM-5-Attenuated Psychosis Syndrome (DSM-5-APS), and their clinical routine practice in the treatment of it. Three vignettes describing fictional cases presented with symptoms of either DSM-5-Schizophrenia, DSM-5-APS, and no psychotic symptoms were created. We asked these practitioners to apply a DSM-5 diagnosis and to choose appropriate treatment(s) for these vignettes. Of the responders, 43% correctly diagnosed the APS vignette, whereas 37.4% mentioned that it had a full-blown psychotic episode. Regarding the therapeutic approach for the APS vignette, 72.1% of all practitioners chose a psychopharmacological intervention and 32% individual psychotherapy. This study showed that the diagnostic inter-rater reliability of the DSM-5-APS among child/adolescent mental health practitioners was consistent with the results from the DSM-5 field trials (Kappa = 0.46). Moreover, almost three in four practitioners endorsed psychopharmacological intervention as a treatment option for the DSM-5-APS case. The lack of evidence of psychopharmacological interventions in CHR-P situations emphasizes that the least harmful interventions should be recommended. Thus, our findings indicated a need for raising awareness regarding the CHR-P paradigm and its treatment as well as the development of solid guidelines that can be implemented in clinical practice.

Scaling Up Global Mental Health Services During the COVID-19 Pandemic and Beyond.

Every health care system requires an adequate health care workforce, service delivery, financial support, and information technology. During the COVID-19 pandemic, global health systems were ill prepared to address the rising prevalence of mental health problems, especially in low- and middle-income countries (LMICs), thereby increasing treatment gaps. To close these gaps globally, task shifting and telepsychiatry should be made available and maximized, particularly in LMICs. Task shifting to nonspecialist health workers to improve essential mental health coverage and encourage efficient use of the available resources and technology has become the most viable strategy.

Rationale and Design of the FREQUENCY Study: The Fetal Cardiac Registry of Québec to Improve Resource Utilization in Fetal Cardiology.

OBJECTIVE: Prenatal detection of congenital heart diseases (CHD) decreases morbidity and cost. To improve detections rates, most physicians refer pregnant women with high-risk pregnancies to fetal cardiologists even when there is no suspicion of CHD at the second trimester screening. This paper presents the rationale and detailed method of the Fetal Cardiac Registry of Québec to Improve Resource Utilization in Fetal Cardiology (FREQUENCY) study. The overall objective is to assess the impact of second trimester ultrasound screening (U/S) and referral pattern in fetal cardiology on detection rates, health care costs, and resource utilization, as well as perinatal morbidity and mortality. METHODS: This multicentre retrospective population-based cohort study will link fetal echocardiography data from all centres performing fetal echocardiography in Québec with administrative health care data. This data linking will allow the determination of a true denominator (all women in Québec who underwent second trimester U/S) with complete follow-up of up to 2 years for offspring. This protocol meets Canadian Task Force Classification II-2. RESULTS: The study investigators have collected and cleaned fetal echocardiography data for 24 259 eligible pregnancies referred to fetal cardiology. These data will be matched to approximately 860 000 pregnancies between 2007 and 2015. CONCLUSION: The results of the FREQUENCY study will shed light on the impact of the current prenatal CHD screening strategy in Canada.

Normalize the response of EPID in pursuit of linear accelerator dosimetry standardization.

Normalize the response of electronic portal imaging device (EPID) is the first step toward an EPID-based standardization of Linear Accelerator (linac) dosimetry quality assurance. In this study, we described an approach to generate two-dimensional (2D) pixel sensitivity maps (PSM) for EPIDs response normalization utilizing an alternative beam and dark-field (ABDF) image acquisition technique and large overlapping field irradiations. The automated image acquisition was performed by XML-controlled machine operation and the PSM was generated based on a recursive calculation algorithm for Varian linacs equipped with aS1000 and aS1200 imager panels. Cross-comparisons of normalized beam profiles and 1.5%/1.5 mm 1D Gamma analysis was adopted to quantify the improvement of beam profile matching before and after PSM corrections. PSMs were derived for both photon (6, 10, 15 MV) and electron (6, 20 MeV) beams via proposed method. The PSM-corrected images reproduced a horn-shaped profile for photon beams and a relative uniform profiles for electrons. For dosimetrically matched linacs equipped with aS1000 panels, PSM-corrected images showed increased 1D-Gamma passing rates for all energies, with an average 10.5% improvement for crossline and 37% for inline beam profiles. Similar improvements in the phantom study were observed with a maximum improvement of 32% for 15 MV and 22% for 20 MeV. The PSM value showed no significant change for all energies over a 3-month period. In conclusion, the proposed approach correct EPID response for both aS1000 and aS1200 panels. This strategy enables the possibility to standardize linac dosimetry QA and to benchmark linac performance utilizing EPID as the common detector.

Risk assessment of a new acceptance testing procedure for conventional linear accelerators.

PURPOSE: New techniques and materials have recently been developed to expedite the conventional linac acceptance testing procedure (Med Phys. 2017;22), which use the electronic portal imaging device (EPID) for data collection. This new procedure is designed to be more efficient and robust than the conventional approach. The purpose of this work was to perform a comparative risk assessment of the two acceptance testing procedures (ATPs). MATERIALS AND METHODS: Failure Modes and Effects Analysis was used to assess risks for both ATP approaches. Five domain experts (Medical Physicists) comprised the analysis team. The risk assessment method and ranking scales were adopted from the AAPM TG-100. The number of failure pathways and associated risk priority numbers (RPNs) for the two ATP approaches were compared. RPNs > 100 were considered high-priority failure modes. RESULTS: Fewer failure pathways were determined for the new ATP (ATPEPID ) compared to the conventional ATP (ATPconv ) resulting in a 44% difference (n = 233 vs. n = 534, respectively). There were also 35% fewer RPNs > 100 for the ATPEPID (n = 40) compared to the ATPconv (n = 114). Failure pathways and RPNs > 100 for individual ATP tests were 2.0 and 3.5 times higher, on average, for the ATPconv compared to the ATPEPID , respectively. The EPID pixel sensitivity map was identified as a high risk failure for the ATPEPID . CONCLUSIONS: Potential errors due to human factors were decreased for the ATPEPID compared to ATPconv so it is possible that a largely automated linac ATP can mitigate many error occurrences. Manufacturers should be careful when designing an EPID-based ATP to address errors in the EPID pixel sensitivity map which can potentially lead to a significant impact on patients' treatment.

Rapid acceptance testing of modern linac using on-board MV and kV imaging systems.

PURPOSE: The purpose of this study was to develop a novel process for using on-board MV and kV Electronic Portal Imaging Devices (EPIDs) to perform linac acceptance testing (AT) for two reasons: (a) to standardize the assessment of new equipment performance, and (b) to reduce the time to clinical use while reducing physicist workload. METHODS AND MATERIALS: In this study, Varian TrueBeam linacs equipped with amorphous silicon-based EPID (aS1000) were used. The conventional set of AT tests and tolerances were used as a baseline guide. A novel methodology was developed or adopted from published literature to perform as many tests as possible using the MV and kV EPIDs. The developer mode on Varian TrueBeam linacs was used to automate the process. In the EPID-based approach, most of mechanical tests were conducted by acquiring images through a custom phantom and software tools were developed for quantitative analysis to extract different performance parameters. The embedded steel-spheres in a custom phantom provided both visual and radiographic guidance for beam geometry testing. For photon beams, open field EPID images were used to extract inline/crossline profiles to verify the beam energy, flatness and symmetry. EPID images through a double wedge phantom were used for evaluating electron beam properties via diagonal profile. Testing was augmented with a commercial automated application (Machine Performance Check) which was used to perform several geometric accuracy tests such as gantry, collimator rotations, and couch rotations/translations. RESULTS: The developed process demonstrated that the tests, which required customer demonstration, were efficiently performed using EPIDs. The AT tests that were performed using EPIDs were fully automated using the developer mode on the Varian TrueBeam system, while some tests, such as the light field versus radiation field congruence, and collision interlock checks required user interaction. CONCLUSIONS: On-board imagers are quite suitable for both geometric and dosimetric testing of linac system involved in AT. Electronic format of the acquired data lends itself to benchmarking, transparency, as well as longitudinal use of AT data. While the tests were performed on a specific model of a linear accelerator, the proposed approach can be extended to other linacs.

FMEA of manual and automated methods for commissioning a radiotherapy treatment planning system.

PURPOSE: To evaluate the level of risk involved in treatment planning system (TPS) commissioning using a manual test procedure, and to compare the associated process-based risk to that of an automated commissioning process (ACP) by performing an in-depth failure modes and effects analysis (FMEA). METHODS: The authors collaborated to determine the potential failure modes of the TPS commissioning process using (a) approaches involving manual data measurement, modeling, and validation tests and (b) an automated process utilizing application programming interface (API) scripting, preloaded, and premodeled standard radiation beam data, digital heterogeneous phantom, and an automated commissioning test suite (ACTS). The severity (S), occurrence (O), and detectability (D) were scored for each failure mode and the risk priority numbers (RPN) were derived based on TG-100 scale. Failure modes were then analyzed and ranked based on RPN. The total number of failure modes, RPN scores and the top 10 failure modes with highest risk were described and cross-compared between the two approaches. RPN reduction analysis is also presented and used as another quantifiable metric to evaluate the proposed approach. RESULTS: The FMEA of a MTP resulted in 47 failure modes with an RPNave of 161 and Save of 6.7. The highest risk process of "Measurement Equipment Selection" resulted in an RPNmax of 640. The FMEA of an ACP resulted in 36 failure modes with an RPNave of 73 and Save of 6.7. The highest risk process of "EPID Calibration" resulted in an RPNmax of 576. CONCLUSIONS: An FMEA of treatment planning commissioning tests using automation and standardization via API scripting, preloaded, and pre-modeled standard beam data, and digital phantoms suggests that errors and risks may be reduced through the use of an ACP.

A comparative study of automatic image segmentation algorithms for target tracking in MR-IGRT.

On-board magnetic resonance (MR) image guidance during radiation therapy offers the potential for more accurate treatment delivery. To utilize the real-time image information, a crucial prerequisite is the ability to successfully segment and track regions of interest (ROI). The purpose of this work is to evaluate the performance of different segmentation algorithms using motion images (4 frames per second) acquired using a MR image-guided radiotherapy (MR-IGRT) system. Manual con-tours of the kidney, bladder, duodenum, and a liver tumor by an experienced radiation oncologist were used as the ground truth for performance evaluation. Besides the manual segmentation, images were automatically segmented using thresholding, fuzzy k-means (FKM), k-harmonic means (KHM), and reaction-diffusion level set evolution (RD-LSE) algorithms, as well as the tissue tracking algorithm provided by the ViewRay treatment planning and delivery system (VR-TPDS). The performance of the five algorithms was evaluated quantitatively by comparing with the manual segmentation using the Dice coefficient and target registration error (TRE) measured as the distance between the centroid of the manual ROI and the centroid of the automatically segmented ROI. All methods were able to successfully segment the bladder and the kidney, but only FKM, KHM, and VR-TPDS were able to segment the liver tumor and the duodenum. The performance of the thresholding, FKM, KHM, and RD-LSE algorithms degraded as the local image contrast decreased, whereas the performance of the VP-TPDS method was nearly independent of local image contrast due to the reference registration algorithm. For segmenting high-contrast images (i.e., kidney), the thresholding method provided the best speed (< 1 ms) with a satisfying accuracy (Dice = 0.95). When the image contrast was low, the VR-TPDS method had the best automatic contour. Results suggest an image quality determination procedure before segmentation and a combination of different methods for optimal segmentation with the on-board MR-IGRT system.

Daily QA of linear accelerators using only EPID and OBI.

PURPOSE: As treatment delivery becomes more complex, there is a pressing need for robust quality assurance (QA) tools to improve efficiency and comprehensiveness while simultaneously maintaining high accuracy and sensitivity. This work aims to present the hardware and software tools developed for comprehensive QA of linear accelerator (LINAC) using only electronic portal imaging devices (EPIDs) and kV flat panel detectors. METHODS: A daily QA phantom, which includes two orthogonally positioned phantoms for QA of MV-beams and kV onboard imaging (OBI) is suspended from the gantry accessory holder to test both geometric and dosimetric components of a LINAC and an OBI. The MV component consists of a 0.5 cm water-equivalent plastic sheet incorporating 11 circular steel plugs for transmission measurements through multiple thicknesses and one resolution plug for MV-image quality testing. The kV-phantom consists of a Leeds phantom (TOR-18 FG phantom supplied by Varian) for testing low and high contrast resolutions. In the developed process, the existing LINAC tools were used to automate daily acquisition of MV and kV images and software tools were developed for simultaneous analysis of these images. A method was developed to derive and evaluate traditional QA parameters from these images [output, flatness, symmetry, uniformity, TPR20/10, and positional accuracy of the jaws and multileaf collimators (MLCs)]. The EPID-based daily QA tools were validated by performing measurements on a detuned 6 MV beam to test its effectiveness in detecting errors in output, symmetry, energy, and MLC positions. The developed QA process was clinically commissioned, implemented, and evaluated on a Varian TrueBeam LINAC (Varian Medical System, Palo Alto, CA) over a period of three months. RESULTS: Machine output constancy measured with an EPID (as compared against a calibrated ion-chamber) is shown to be within ±0.5%. Beam symmetry and flatness deviations measured using an EPID and a 2D ion-chamber array agree within ±0.5% and ±1.2% for crossline and inline profiles, respectively. MLC position errors of 0.5 mm can be detected using a picket fence test. The field size and phantom positioning accuracy can be determined within 0.5 mm. The entire daily QA process takes ∼15 min to perform tests for 5 photon beams, MLC tests, and imaging checks. CONCLUSIONS: The exclusive use of EPID-based QA tools, including a QA phantom and simultaneous analysis software tools, has been demonstrated as a viable, efficient, and comprehensive process for daily evaluation of LINAC performance.

Comparison of onboard low-field magnetic resonance imaging versus onboard computed tomography for anatomy visualization in radiotherapy.

BACKGROUND: Onboard magnetic resonance imaging (OB-MRI) for daily localization and adaptive radiotherapy has been under development by several groups. However, no clinical studies have evaluated whether OB-MRI improves visualization of the target and organs at risk (OARs) compared to standard onboard computed tomography (OB-CT). This study compared visualization of patient anatomy on images acquired on the MRI-(60)Co ViewRay system to those acquired with OB-CT. MATERIAL AND METHODS: Fourteen patients enrolled on a protocol approved by the Institutional Review Board (IRB) and undergoing image-guided radiotherapy for cancer in the thorax (n = 2), pelvis (n = 6), abdomen (n = 3) or head and neck (n = 3) were imaged with OB-MRI and OB-CT. For each of the 14 patients, the OB-MRI and OB-CT datasets were displayed side-by-side and independently reviewed by three radiation oncologists. Each physician was asked to evaluate which dataset offered better visualization of the target and OARs. A quantitative contouring study was performed on two abdominal patients to assess if OB-MRI could offer improved inter-observer segmentation agreement for adaptive planning. RESULTS: In total 221 OARs and 10 targets were compared for visualization on OB-MRI and OB-CT by each of the three physicians. The majority of physicians (two or more) evaluated visualization on MRI as better for 71% of structures, worse for 10% of structures, and equivalent for 14% of structures. 5% of structures were not visible on either. Physicians agreed unanimously for 74% and in majority for > 99% of structures. Targets were better visualized on MRI in 4/10 cases, and never on OB-CT. CONCLUSION: Low-field MR provides better anatomic visualization of many radiotherapy targets and most OARs as compared to OB-CT. Further studies with OB-MRI should be pursued.

Process-based quality management for clinical implementation of adaptive radiotherapy.

PURPOSE: Intensity-modulated adaptive radiotherapy (ART) has been the focus of considerable research and developmental work due to its potential therapeutic benefits. However, in light of its unique quality assurance (QA) challenges, no one has described a robust framework for its clinical implementation. In fact, recent position papers by ASTRO and AAPM have firmly endorsed pretreatment patient-specific IMRT QA, which limits the feasibility of online ART. The authors aim to address these obstacles by applying failure mode and effects analysis (FMEA) to identify high-priority errors and appropriate risk-mitigation strategies for clinical implementation of intensity-modulated ART. METHODS: An experienced team of two clinical medical physicists, one clinical engineer, and one radiation oncologist was assembled to perform a standard FMEA for intensity-modulated ART. A set of 216 potential radiotherapy failures composed by the forthcoming AAPM task group 100 (TG-100) was used as the basis. Of the 216 failures, 127 were identified as most relevant to an ART scheme. Using the associated TG-100 FMEA values as a baseline, the team considered how the likeliness of occurrence (O), outcome severity (S), and likeliness of failure being undetected (D) would change for ART. New risk priority numbers (RPN) were calculated. Failures characterized by RPN ≥ 200 were identified as potentially critical. RESULTS: FMEA revealed that ART RPN increased for 38% (n = 48/127) of potential failures, with 75% (n = 36/48) attributed to failures in the segmentation and treatment planning processes. Forty-three of 127 failures were identified as potentially critical. Risk-mitigation strategies include implementing a suite of quality control and decision support software, specialty QA software/hardware tools, and an increase in specially trained personnel. CONCLUSIONS: Results of the FMEA-based risk assessment demonstrate that intensity-modulated ART introduces different (but not necessarily more) risks than standard IMRT and may be safely implemented with the proper mitigations.

Segmentation precision of abdominal anatomy for MRI-based radiotherapy.

The limited soft tissue visualization provided by computed tomography, the standard imaging modality for radiotherapy treatment planning and daily localization, has motivated studies on the use of magnetic resonance imaging (MRI) for better characterization of treatment sites, such as the prostate and head and neck. However, no studies have been conducted on MRI-based segmentation for the abdomen, a site that could greatly benefit from enhanced soft tissue targeting. We investigated the interobserver and intraobserver precision in segmentation of abdominal organs on MR images for treatment planning and localization. Manual segmentation of 8 abdominal organs was performed by 3 independent observers on MR images acquired from 14 healthy subjects. Observers repeated segmentation 4 separate times for each image set. Interobserver and intraobserver contouring precision was assessed by computing 3-dimensional overlap (Dice coefficient [DC]) and distance to agreement (Hausdorff distance [HD]) of segmented organs. The mean and standard deviation of intraobserver and interobserver DC and HD values were DC(intraobserver) = 0.89 ± 0.12, HD(intraobserver) = 3.6mm ± 1.5, DC(interobserver) = 0.89 ± 0.15, and HD(interobserver) = 3.2mm ± 1.4. Overall, metrics indicated good interobserver/intraobserver precision (mean DC > 0.7, mean HD < 4mm). Results suggest that MRI offers good segmentation precision for abdominal sites. These findings support the utility of MRI for abdominal planning and localization, as emerging MRI technologies, techniques, and onboard imaging devices are beginning to enable MRI-based radiotherapy.

Quality Assurance with Plan Veto: reincarnation of a record and verify system and its potential value.

PURPOSE: To quantify the potential impact of the Integrating the Healthcare Enterprise-Radiation Oncology Quality Assurance with Plan Veto (QAPV) on patient safety of external beam radiation therapy (RT) operations. METHODS AND MATERIALS: An institutional database of events (errors and near-misses) was used to evaluate the ability of QAPV to prevent clinically observed events. We analyzed reported events that were related to Digital Imaging and Communications in Medicine RT plan parameter inconsistencies between the intended treatment (on the treatment planning system) and the delivered treatment (on the treatment machine). Critical Digital Imaging and Communications in Medicine RT plan parameters were identified. Each event was scored for importance using the Failure Mode and Effects Analysis methodology. Potential error occurrence (frequency) was derived according to the collected event data, along with the potential event severity, and the probability of detection with and without the theoretical implementation of the QAPV plan comparison check. Failure Mode and Effects Analysis Risk Priority Numbers (RPNs) with and without QAPV were compared to quantify the potential benefit of clinical implementation of QAPV. RESULTS: The implementation of QAPV could reduce the RPN values for 15 of 22 (71%) of evaluated parameters, with an overall average reduction in RPN of 68 (range, 0-216). For the 6 high-risk parameters (>200), the average reduction in RPN value was 163 (range, 108-216). The RPN value reduction for the intermediate-risk (200 > RPN > 100) parameters was (0-140). With QAPV, the largest RPN value for "Beam Meterset" was reduced from 324 to 108. The maximum reduction in RPN value was for Beam Meterset (216, 66.7%), whereas the maximum percentage reduction was for Cumulative Meterset Weight (80, 88.9%). CONCLUSION: This analysis quantifies the value of the Integrating the Healthcare Enterprise-Radiation Oncology QAPV implementation in clinical workflow. We demonstrate that although QAPV does not provide a comprehensive solution for error prevention in RT, it can have a significant impact on a subset of the most severe clinically observed events.

A respiratory correlated image guided surgery method: quantitative accuracy results in swine and human cadaver environments.

BACKGROUND: Intervention on small targets in the lung is difficult, leading our team to develop a highly accurate respiratory correlated image guided surgery (RCIGS) system. METHODS: Simulated point source targets were implanted into ex vivo porcine and human cadaver lungs attached to a ventilator. The RCIGS system was utilized to guide intervention in the presence of respiratory motion using a commercially available electromagnetic tracking solution. After intervention, the lungs were imaged to determine the target registration error between the target and needle. RESULTS: The system tumor position modeling had sub-mm accuracy. The mean intervention error for 12 porcine targets was 3.8 mm. The mean target registration error on four targets in a human cadaver was 4.0 mm at a mean depth of 9 cm. CONCLUSIONS: The system provides an accuracy for intervention on targets of less than 1 cm in diameter at depths of up to 10 cm. A system of this accuracy outperforms current clinical standards.

Planning 4-dimensional computed tomography (4DCT) cannot adequately represent daily intrafractional motion of abdominal tumors.

PURPOSE: To evaluate whether planning 4-dimensional computed tomography (4DCT) can adequately represent daily motion of abdominal tumors in regularly fractionated and stereotactic body radiation therapy (SBRT) patients. METHODS AND MATERIALS: Intrafractional tumor motion of 10 patients with abdominal tumors (4 pancreas-fractionated and 6 liver-stereotactic patients) with implanted fiducials was measured based on daily orthogonal fluoroscopic movies over 38 treatment fractions. The needed internal margin for at least 90% of tumor coverage was calculated based on a 95th and fifth percentile of daily 3-dimensional tumor motion. The planning internal margin was generated by fusing 4DCT motion from all phase bins. The disagreement between needed and planning internal margin was analyzed fraction by fraction in 3 motion axes (superior-inferior [SI], anterior-posterior [AP], and left-right [LR]). The 4DCT margin was considered as an overestimation/underestimation of daily motion when disagreement exceeded at least 3 mm in the SI axis and/or 1.2 mm in the AP and LR axes (4DCT image resolution). The underlying reasons for this disagreement were evaluated based on interfractional and intrafractional breathing variation. RESULTS: The 4DCT overestimated daily 3-dimensional motion in 39% of the fractions in 7 of 10 patients and underestimated it in 53% of the fractions in 8 of 10 patients. Median underestimation was 3.9 mm, 3.0 mm, and 1.7 mm in the SI axis, AP axis, and LR axis, respectively. The 4DCT was found to capture irregular deep breaths in 3 of 10 patients, with 4DCT motion larger than mean daily amplitude by 18 to 21 mm. The breathing pattern varied from breath to breath and day to day. The intrafractional variation of amplitude was significantly larger than intrafractional variation (2.7 mm vs 1.3 mm) in the primary motion axis (ie, SI axis). The SBRT patients showed significantly larger intrafractional amplitude variation than fractionated patients (3.0 mm vs 2.1 mm, P<.05). CONCLUSIONS: It may not be appropriate to use 4DCT without monitoring of patient motion on a regular basis for patients with abdominal tumors, especially SBRT patients.

Clinical evaluation of a commercial orthopedic metal artifact reduction tool for CT simulations in radiation therapy.

PURPOSE: Severe artifacts in kilovoltage-CT simulation images caused by large metallic implants can significantly degrade the conspicuity and apparent CT Hounsfield number of targets and anatomic structures, jeopardize the confidence of anatomical segmentation, and introduce inaccuracies into the radiation therapy treatment planning process. This study evaluated the performance of the first commercial orthopedic metal artifact reduction function (O-MAR) for radiation therapy, and investigated its clinical applications in treatment planning. METHODS: Both phantom and clinical data were used for the evaluation. The CIRS electron density phantom with known physical (and electron) density plugs and removable titanium implants was scanned on a Philips Brilliance Big Bore 16-slice CT simulator. The CT Hounsfield numbers of density plugs on both uncorrected and O-MAR corrected images were compared. Treatment planning accuracy was evaluated by comparing simulated dose distributions computed using the true density images, uncorrected images, and O-MAR corrected images. Ten CT image sets of patients with large hip implants were processed with the O-MAR function and evaluated by two radiation oncologists using a five-point score for overall image quality, anatomical conspicuity, and CT Hounsfield number accuracy. By utilizing the same structure contours delineated from the O-MAR corrected images, clinical IMRT treatment plans for five patients were computed on the uncorrected and O-MAR corrected images, respectively, and compared. RESULTS: Results of the phantom study indicated that CT Hounsfield number accuracy and noise were improved on the O-MAR corrected images, especially for images with bilateral metal implants. The γ pass rates of the simulated dose distributions computed on the uncorrected and O-MAR corrected images referenced to those of the true densities were higher than 99.9% (even when using 1% and 3 mm distance-to-agreement criterion), suggesting that dose distributions were clinically identical. In all patient cases, radiation oncologists rated O-MAR corrected images as higher quality. Formerly obscured critical structures were able to be visualized. The overall image quality and the conspicuity in critical organs were significantly improved compared with the uncorrected images: overall quality score (1.35 vs 3.25, P = 0.0022); bladder (2.15 vs 3.7, P = 0.0023); prostate and seminal vesicles∕vagina (1.3 vs 3.275, P = 0.0020); rectum (2.8 vs 3.9, P = 0.0021). The noise levels of the selected ROIs were reduced from 93.7 to 38.2 HU. On most cases (8∕10), the average CT Hounsfield numbers of the prostate∕vagina on the O-MAR corrected images were closer to the referenced value (41.2 HU, an average measured from patients without metal implants) than those on the uncorrected images. High γ pass rates of the five IMRT dose distribution pairs indicated that the dose distributions were not significantly affected by the CT image improvements. CONCLUSIONS: Overall, this study indicated that the O-MAR function can remarkably reduce metal artifacts and improve both CT Hounsfield number accuracy and target and critical structure visualization. Although there was no significant impact of the O-MAR algorithm on the calculated dose distributions, we suggest that O-MAR corrected images are more suitable for the entire treatment planning process by offering better anatomical structure visualization, improving radiation oncologists' confidence in target delineation, and by avoiding subjective density overrides of artifact regions on uncorrected images.