An image-based method to synchronize cone-beam CT and optical surface tracking

open5siThe integration of in-room X-ray imaging and optical surface tracking has gained increasing importance in the field of image guided radiotherapy (IGRT). An essential step for this integration consists of temporally synchronizing the acquisition of X-ray projections and surface data. We present an image-based method for the synchronization of cone-beam computed tomography (CBCT) and optical surface systems, which does not require the use of additional hardware. The method is based on optically tracking the motion of a component of the CBCT/gantry unit, which rotates during the acquisition of the CBCT scan. A calibration procedure was implemented to relate the position of the rotating component identified by the optical system with the time elapsed since the beginning of the CBCT scan, thus obtaining the temporal correspondence between the acquisition of X-ray projections and surface data. The accuracy of the proposed synchronization method was evaluated on a motorized moving phantom, performing eight simultaneous acquisitions with an Elekta Synergy CBCT machine and the AlignRT optical device. The median time difference between the sinusoidal peaks of phantom motion signals extracted from the synchronized CBCT and AlignRT systems ranged between -3.1 and 12.9 msec, with a maximum interquartile range of 14.4 msec. The method was also applied to clinical data acquired from seven lung cancer patients, demonstrating the potential of the proposed approach in estimating the individual and daily variations in respiratory parameters and motion correlation of internal and external structures. The presented synchronization method can be particularly useful for tumor tracking applications in extracranial radiation treatments, especially in the field of patient-specific breathing models, based on the correlation between internal tumor motion and external surface surrogates.Fassi, Aurora; Schaerer, Joël; Riboldi, Marco; Sarrut, David; Baroni, GuidoFassi, Aurora; Schaerer, Joël; Riboldi, Marco; Sarrut, David; Baroni, Guid

Modality-Agnostic Learning for Medical Image Segmentation Using Multi-modality Self-distillation

Medical image segmentation of tumors and organs at risk is a time-consuming yet critical process in the clinic that utilizes multi-modality imaging (e.g, different acquisitions, data types, and sequences) to increase segmentation precision. In this paper, we propose a novel framework, Modality-Agnostic learning through Multi-modality Self-dist-illation (MAG-MS), to investigate the impact of input modalities on medical image segmentation. MAG-MS distills knowledge from the fusion of multiple modalities and applies it to enhance representation learning for individual modalities. Thus, it provides a versatile and efficient approach to handle limited modalities during testing. Our extensive experiments on benchmark datasets demonstrate the high efficiency of MAG-MS and its superior segmentation performance than current state-of-the-art methods. Furthermore, using MAG-MS, we provide valuable insight and guidance on selecting input modalities for medical image segmentation tasks

Auditoría administrativa para evaluar la gestión de las pequeñas y medianas empresas de Ayacucho 2017

Esta investigación trata sobre la relación entre la auditoria administrativa y la gestión de las pequeñas y medianas empresas de Ayacucho, 2017. La investigación tuvo un enfoque cuantitativo, basado en el diseño correlacional-descriptivo y corte transversal. En la recolección de datos se utilizó la encuesta, las cuales fueron dirigidas a 20 gerentes. Para determinar el grado de correlación de las variables se utilizó la prueba estadística de coeficiente de Spearman. La principal conclusión indica que estadísticamente sí existe la relación entre la auditoria administrativa y la gestión de pequeñas y medianas empresas en Ayacucho, 2017, como se demostró según la prueba de correlación de Spearman, donde los resultados afirman una correlación positiva débil de r= 0,492 con un margen de error del 5%. El p – valor es de 0,028, que según la regla de decisión prueba la existencia de relación de ambas variables. En la principal recomendación se indica la aplicación de manera periódica una auditoria administrativa en las medianas y grandes empresas de Ayacucho, con el objetivo de conocer la situación frente a sus objetivos, metas y tomar las decisiones necesarias

Relación del estilo de liderazgo de la enfermera jefe y la satisfacción laboral del personal técnico de enfermería en los centros de salud y puestos de la Microred La Esperanza - La Esperanza - Trujillo 2017

El presente estudio de investigación cuantitativo de tipo, descriptivo correlacional de corte transversal, se realizó durante los meses de julio a diciembre del 2017; con la finalidad de determinar el estilo de liderazgo de la enfermera jefe en los Centros y Puestos de Salud de la Microred La Esperanza; y, el nivel de satisfacción laboral del personal técnico de enfermería de dichos centros. El universo estuvo constituido por 92 técnicos de enfermería seleccionados según criterios de inclusión, a quienes se les aplico los instrumentos: Escala Valorativa del estilo de liderazgo y la escala de satisfacción – insatisfacción laboral Herzbergiana; se respetaron los derechos de confidencialidad y participación voluntaria. Los datos fueron procesados y analizados por el programa SPPS ver. 20 y los resultados se procesaron en tablas de una y doble entrada. Los resultados muestran que el 70.7 por ciento de enfermeras jefes, practican el estilo de liderazgo transformacional, el 37.0 por ciento del personal técnico tiene un nivel de satisfacción laboral media. Así mismo se reporta una correlación positiva y altanamente significativa (r = 0.65, p < 0.01), entre el estilo transformacional y la satisfacción laboral; y una influencia altamente significativa también, (x 2 =16.613, p < 0.01) entre el estilo de liderazgo y satisfacción laboral.Tesi

Relación del estilo de liderazgo de la enfermera jefe y la satisfacción laboral del personal técnico de enfermería en los centros de salud y puestos de la Microred La Esperanza - La Esperanza - Trujillo 2017

El presente estudio de investigación cuantitativo de tipo, descriptivo correlacional de corte transversal, se realizó durante los meses de julio a diciembre del 2017; con la finalidad de determinar el estilo de liderazgo de la enfermera jefe en los Centros y Puestos de Salud de la Microred La Esperanza; y, el nivel de satisfacción laboral del personal técnico de enfermería de dichos centros. El universo estuvo constituido por 92 técnicos de enfermería seleccionados según criterios de inclusión, a quienes se les aplico los instrumentos: Escala Valorativa del estilo de liderazgo y la escala de satisfacción – insatisfacción laboral Herzbergiana; se respetaron los derechos de confidencialidad y participación voluntaria. Los datos fueron procesados y analizados por el programa SPPS ver. 20 y los resultados se procesaron en tablas de una y doble entrada. Los resultados muestran que el 70.7 por ciento de enfermeras jefes, practican el estilo de liderazgo transformacional, el 37.0 por ciento del personal técnico tiene un nivel de satisfacción laboral media. Así mismo se reporta una correlación positiva y altanamente significativa (r = 0.65, p < 0.01), entre el estilo transformacional y la satisfacción laboral; y una influencia altamente significativa también, (x 2 =16.613, p < 0.01) entre el estilo de liderazgo y satisfacción laboral.Tesi

FMEA of MR-Only Treatment Planning in the Pelvis

Purpose: To evaluate the implementation of a magnetic resonance (MR)-only workflow (ie, implementing MR simulation as the primary planning modality) using failure mode and effects analysis (FMEA) in comparison with a conventional multimodality (MR simulation in conjunction with computed tomography simulation) workflow for pelvis external beam planning. Methods and Materials: To perform the FMEA, a multidisciplinary 9-member team was assembled and developed process maps, identified potential failure modes (FMs), and assigned numerical values to the severity (S), frequency of occurrence (O), and detectability (D) of those FMs. Risk priority numbers (RPNs) were calculated via the product of S, O, and D as a metric for evaluating relative patient risk. An alternative 3-digit composite number (SOD) was computed to emphasize high-severity FMs. Fault tree analysis identified the causality chain leading to the highest-severity FM. Results: Seven processes were identified, 3 of which were shared between workflows. Image fusion and target delineation subprocesses using the conventional workflow added 9 and 10 FMs, respectively, with 6 RPNs \u3e100. By contrast, synthetic computed tomography generation introduced 3 major subprocesses and propagated 46 unique FMs, 15 with RPNs \u3e100. For the conventional workflow, the largest RPN scores were introduced by image fusion (RPN range, 120-192). For the MR-only workflow, the highest RPN scores were from inaccuracies in target delineation resulting from misinterpretation of MR images (RPN = 240) and insufficient management of patient- and system-level distortions (RPN = 210 and 168, respectively). Underestimation (RPN = 140) or overestimation (RPN = 192) of bone volume produced higher RPN scores. The highest SODs for both workflows were related to changes in target location because of internal anatomy changes (conventional = 961, MR-only = 822). Conclusions: FMEA identified areas for mitigating risk in MR-only pelvis RTP, and SODs identified high-severity process modes. Efforts to develop a quality management program to mitigate high FMs are underway

Incorporating sensitive cardiac substructure sparing into radiation therapy planning

PURPOSE: Rising evidence suggests that cardiac substructures are highly radiosensitive. However, they are not routinely considered in treatment planning as they are not readily visualized on treatment planning CTs (TPCTs). This work integrated the soft tissue contrast provided by low-field MRIs acquired on an MR-linac via image registration to further enable cardiac substructure sparing on TPCTs. METHODS: Sixteen upper thoracic patients treated at various breathing states (7 end-exhalation, 7 end-inhalation, 2 free-breathing) on a 0.35T MR-linac were retrospectively evaluated. A hybrid MR/CT atlas and a deep learning three-dimensional (3D) U-Net propagated 13 substructures to TPCTs. Radiation oncologists revised contours using registered MRIs. Clinical treatment plans were re-optimized and evaluated for beam arrangement modifications to reduce substructure doses. Dosimetric assessment included mean and maximum (0.03cc) dose, left ventricular volume receiving 5Gy (LV-V5), and other clinical endpoints. As metrics of plan complexity, total MU and treatment time were evaluated between approaches. RESULTS: Cardiac sparing plans reduced the mean heart dose (mean reduction 0.7 ± 0.6, range 0.1 to 2.5 Gy). Re-optimized plans reduced left anterior descending artery (LADA) mean and LADA(0.03cc) (0.0-63.9% and 0.0 to 17.3 Gy, respectively). LV(0.03cc) was reduced by \u3e1.5 Gy for 10 patients while 6 cases had large reductions (\u3e7%) in LV-V5. Left atrial mean dose was equivalent/reduced in all sparing plans (mean reduction 0.9 ± 1.2 Gy). The left main coronary artery was better spared in all cases for mean dose and D(0.03cc) . One patient exhibited \u3e10 Gy reduction in D(0.03cc) to four substructures. There was no statistical difference in treatment time and MU, or clinical endpoints to the planning target volume, lung, esophagus, or spinal cord after re-optimization. Four patients benefited from new beam arrangements, leading to further dose reductions. CONCLUSIONS: By introducing 0.35T MRIs acquired on an MR-linac to verify cardiac substructure segmentations for CT-based treatment planning, an opportunity was presented for more effective sparing with limited increase in plan complexity. Validation in a larger cohort with appropriate margins offers potential to reduce radiation-related cardiotoxicities

Multi-Parametric MRI for Radiotherapy Simulation

Magnetic resonance imaging (MRI) has become an important imaging modality in the field of radiotherapy (RT) in the past decade, especially with the development of various novel MRI and image-guidance techniques. In this review article, we will describe recent developments and discuss the applications of multi-parametric MRI (mpMRI) in RT simulation. In this review, mpMRI refers to a general and loose definition which includes various multi-contrast MRI techniques. Specifically, we will focus on the implementation, challenges, and future directions of mpMRI techniques for RT simulation