Dejar de hacer lo que no hay que hacer / Ceasing to do what shouldn't be done

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Grado de conocimiento de la campaña Compromiso por la Calidad y de las recomendaciones no hacer entre médicos de familia, pediatras y enfermería de Atención Primaria / Level of knowledge of Quality Commitment Campaign and of "do not do" recommendations amongst general practitioners, pediatricians and nursing Primary Care

Fundamento: Evaluar si la iniciativa campaña Compromiso por la Calidad (ICC) era suficientemente conocida entre profesionales de atención primaria (AP), y valorar el grado de conocimiento de determinadas recomendaciones de lo que no debiera hacerse dirigidas a profesionales de AP. Material y métodos: Estudio observacional basado en un muestreo de conveniencia a profesionales de medicina de familia (MF), pediatría (PED) y enfermería (ENF). Se formuló una pregunta directa sobre si se conocía la ICC y una serie de preguntas dicotómicas basadas en las recomendaciones No Hacer para valorar el nivel de conocimiento. Se consideró necesario un tamaño muestral mínimo de 288 profesionales por cada colectivo, considerando un error del 5%, nivel de confianza del 95% y p=0,75. El estudio de campo se realizó con la colaboración de diversos servicios de salud y organizaciones profesionales y científicas. Los datos se describieron como frecuencias o media (desviación típica), y se compararon mediante χ2/Fisher o ANOVA y t-test. Resultados: Respondieron 1.904 profesionales (936 MF, 682 PED y 286 ENF). De ellos, 828 (43,5%) conocían la ICC: 524 (56,0%) MF, 234 (34,3%) PED y 70 (24,5%) ENF (p<0,001). Respondieron correctamente a todas las preguntas 652 (69,7%) MF, 631 (92,5%) PED y 116 (40,6%) ENF. Cometieron significativamente más errores (p<0,001) quienes no conocían la ICC, trabajaban en el sector privado o no se consideraban responsables de la sobreutilización. Pese a no conocer la ICC, 60% MF y 90% PED contestaron correctamente a todas las preguntas del test. Conclusiones: ENF y MF podrían beneficiarse de una mayor difusión de la ICC. También quienes trabajan en el sector privado y quienes creen que los profesionales tienen escasa responsabilidad en la sobreutilización innecesaria

Background: To evaluate if the Quality Commitment Campaign (QCC) was sufficiently known among primary care professionals (PC), and second, to evaluate the knowledge about certain recommendations of what should not be done in PC. Methods: A observational study was conducted. General practitioners (GP), pediatricians (PED) and nursing (NUR) participated. A direct question was asked about whether QCC was known and a set of dichotomous questions based on the "do not do" recommendations to assess their knowledge. A sample size of 288 professionals from each group was the minimum required for a sampling error of 5%, 95% confidence level and p=0.75. The field study was conducted with the collaboration of health services and professional and scientific organizations. Data were described by frequencies and mean (standard deviation), and compared by means of χ2/Fisher or ANOVA and t-test. Results: A total of 1,904 professionals (936 GP, 682 PED and 286 NUR) answered. The QCC initiative was known by 828 (43.5%) professionals: 524 (56.0%) GP, 234 (34.3%) PED and 70 (24.5%) NUR (p<0.001). All the questions were correctly answered by 652 (69.7%) GP, 631 (92.5%) PED and 116 (40.6%) NUR. Significantly more mistakes (p<0.001) were made by those who did not know the QCC, worked in the private sector or were not considered responsible for overuse. Despite not knowing the QCC, 60% GP and 90% PED answered all the questions of the test correctly. Conclusions: NUR and GP could benefit from a greater diffusion of the QCC. As could those working in the private sector and those who believe that professionals have little responsibility for unnecessary overuse

[Level of knowledge of Quality Commitment Campaign and of "do not do" recommendations amongst general practitioners, pediatricians and nurses Primary Care]. / Grado de conocimiento de la campaña Compromiso por la Calidad y de las recomendaciones no hacer entre médicos de familia, pediatras y enfermería de Atención Primaria.

BACKGROUND: To evaluate if the Quality Commitment Campaign (QCC) was sufficiently known among primary care professionals (PC), and second, to evaluate the knowledge about certain recommendations of what should not be done in PC. METHODS: A observational study was conducted. General practitioners (GP), pediatricians (PED) and nursing (NUR) participated. A direct question was asked about whether QCC was known and a set of dichotomous questions based on the "do not do" recommendations to assess their knowledge. A sample size of 288 professionals from each group was the minimum required for a sampling error of 5%, 95% confidence level and p=0.75. The field study was conducted with the collaboration of health services and professional and scientific organizations. Data were described by frequencies and mean (standard deviation), and compared by means of ?2/Fisher or ANOVA and t-test. RESULTS: A total of 1,904 professionals (936 GP, 682 PED and 286 NUR) answered. The QCC initiative was known by 828 (43.5%) professionals: 524 (56.0%) GP, 234 (34.3%) PED and 70 (24.5%) NUR (p<0.001). All the questions were correctly answered by 652 (69.7%) GP, 631 (92.5%) PED and 116 (40.6%) NUR. Significantly more mistakes (p<0.001) were made by those who did not know the QCC, worked in the private sector or were not considered responsible for overuse. Despite not knowing the QCC, 60% GP and 90% PED answered all the questions of the test correctly. CONCLUSIONS: NUR and GP could benefit from a greater diffusion of the QCC. As could those working in the private sector and those who believe that professionals have little responsibility for unnecessary overuse.

[Proposals for the study of the second victim phenomenon in Spanish Primary Care Centres and Hospitals]. / Propuestas para el estudio del fenómeno de las segundas víctimas en España en atención primaria y hospitales.

OBJECTIVE: To identify the Spanish studies conducted since 2014 on second victims. Its main objective was to identify a global response to the second victim problem, assessing the impact of adverse events (AE) on caregivers and developing of a set of tools to reduce their impact. METHOD: Descriptive studies in which a sample of managers and safety coordinators from Hospitals and Primary Care were surveyed to determine the activities being carried out as regards second victims, as well as a sample of health professionals to describe their experience as a second victims. Qualitative studies are included to design a guide of recommended actions following an AE, an online awareness program on this phenomenon, an application (app) with activities on safety that are the responsibility of the managers, and a web tool for the analysis of AEs. RESULTS: A total of 1,493 professionals (managers, safety coordinators and caregivers) from eight Spanish regions participated. The guide of recommendations, the online program, and the developed applications are accessible on the website: www.segundasvictimas.es, which has received more than 2,500 visits in one year. DISCUSSION: Study results represent a starting point in the study of the second victim phenomenon in Spain. The tools developed raise the awareness of the medical healthcare community about this problem, and provide professionals with basic skills to manage the impact of AEs.

Propuestas para el estudio del fenómeno de las segundas víctimas en España en atención primaria y hospitales / Proposals for the study of the second victim phenomenon in Spanish primary care centres and hospitals

Objetivo. Identificar los enfoques metodológicos y avances de un conjunto de estudios que se han realizado en España desde 2014 en la línea de investigación sobre segundas víctimas, mediante la evaluación del impacto de los eventos adversos (EA) en los profesionales sanitarios. Elaborar un conjunto de herramientas de ayuda para reducir su impacto. Método. Estudio descriptivo en el que se encuestó a directivos y coordinadores de seguridad de hospitales y atención primaria para conocer qué actividades se estaban llevando a cabo en materia de segundas víctimas, y a profesionales asistenciales para describir su posible experiencia como segundas víctimas, junto a estudios cualitativos para diseñar una guía de acciones recomendadas tras un EA, un programa online de sensibilización sobre este fenómeno, una app con actividades en seguridad responsabilidad de los directivos y una herramienta web para el análisis de los EA. Resultados. Participaron 1.493 profesionales (directivos, coordinadores de seguridad y personal asistencial) de 8 comunidades autónomas. La guía de recomendaciones, el programa online y las aplicaciones desarrolladas se encuentran accesibles en el sitio web: www.segundasvictimas.es, que recibió más de 2.500 visitas en un año. Discusión. Los resultados del estudio representan un punto de partida en el estudio del fenómeno de las segundas víctimas en España. Las herramientas desarrolladas sensibilizan a la comunidad sanitaria acerca de esta problemática y dotan a los profesionales de habilidades para gestionar el impacto de los EA (AU)

Objective. To identify the Spanish studies conducted since 2014 on second victims. Its main objective was to identify a global response to the second victim problem, assessing the impact of adverse events (AE) on caregivers and developing of a set of tools to reduce their impact. Method. Descriptive studies in which a sample of managers and safety coordinators from Hospitals and Primary Care were surveyed to determine the activities being carried out as regards second victims, as well as a sample of health professionals to describe their experience as a second victims. Qualitative studies are included to design a guide of recommended actions following an AE, an online awareness program on this phenomenon, an application (app) with activities on safety that are the responsibility of the managers, and a web tool for the analysis of AEs. Results. A total of 1,493 professionals (managers, safety coordinators and caregivers) from eight Spanish regions participated. The guide of recommendations, the online program, and the developed applications are accessible on the website: www.segundasvictimas.es, which has received more than 2,500 visits in one year. Discussion. Study results represent a starting point in the study of the second victim phenomenon in Spain. The tools developed raise the awareness of the medical healthcare community about this problem, and provide professionals with basic skills to manage the impact of AEs (AU)

WE-E-BRB-05: A Novel Detector Dose Calculation Model for in Vivo Delivery Verification of IMRT Treatments.

PURPOSE: Exit 2D detectors are widely used in clinics as a tool for pre- treatment field verification. It is desired to have accurate modeling of the detector dose for each IMRT plan with patient geometry for in-vivo delivery verification. We propose a novel hybrid of model and measurement based methods to estimate the detector dose using the information from TPS and plan/verification CT. METHODS: Our approach is based on the generalized equivalent field size (GEFS) method. It requires two commissioning tables for various square fields (l×l, 2×2, …40×40): the percent depth dose (PDD) table and the detector correction factor (DDCF) table. PDDs are retrieved from the treatment planning system (TPS), and DDCFs are reconstructed from measurement with various field sizes and air gaps (from 5 cm to 50 cm). GEFS models the detector point dose as the superposition of annular contribution of the fluence map, which is retrieved from the TPS. Correction on the radiological path length is calculated through ray-tracing the patient CT. Corrections on the air gap between the couch and detector and detector response are applied via table lookup on PDD and DDCF. RESULTS: We validated the proposed method using TPS with extended geometry and direct clinic measurements for both regular and IMRT fields, various phantom and patient geometry. For all calculations, more than 98% of pixels pass the gamma index with criteria of 3%, 3mm. Each calculation took only a few seconds on a single PC. CONCLUSIONS: We proposed a novel detector dose calculation method that can be applied for arbitrary IMRT field and arbitrary patient geometry. The calculation is simple and fast and when compared with detector measurement during IMRT treatment, makes in- vivo delivery verification and dose reconstruction feasible.

On the relationships between electron spot size, focal spot size, and virtual source position in Monte Carlo simulations.

PURPOSE: Every year, new radiotherapy techniques including stereotactic radiosurgery using linear accelerators give rise to new applications of Monte Carlo (MC) modeling. Accurate modeling requires knowing the size of the electron spot, one of the few parameters to tune in MC models. The resolution of integrated megavoltage imaging systems, such as the tomotherapy system, strongly depends on the photon spot size which is closely related to the electron spot. The aim of this article is to clarify the relationship between the electron spot size and the photon spot size (i.e., the focal spot size) for typical incident electron beam energies and target thicknesses. METHODS: Three electron energies (3, 5.5, and 18 MeV), four electron spot sizes (FWHM = 0, 0.5, 1, and 1.5 mm), and two tungsten target thicknesses (0.15 and 1 cm) were considered. The formation of the photon beam within the target was analyzed through electron energy deposition with depth, as well as photon production at several phase-space planes placed perpendicular to the beam axis, where only photons recorded for the first time were accounted for. Photon production was considered for "newborn" photons intersecting a 45 x 45 cm2 plane at the isocenter (85 cm from source). Finally, virtual source position and "effective" focal spot size were computed by back-projecting all the photons from the bottom of the target intersecting a 45 x 45 cm2 plane. The virtual source position and focal spot size were estimated at the plane position where the latter is minimal. RESULTS: In the relevant case of considering only photons intersecting the 45 x 45 cm2 plane, the results unambiguously showed that the effective photon spot is created within the first 0.25 mm of the target and that electron and focal spots may be assumed to be equal within 3-4%. CONCLUSIONS: In a good approximation photon spot size equals electron spot size for high energy X-ray treatments delivered by linear accelerators.

Preimplantation genetic diagnosis for gender selection in the USA.

Preimplantation genetic diagnosis (PGD) for gender selection for non-medical reasons has been considered an unethical procedure by several authors and agencies in the Western society on the basis that it could disrupt the sex ratio, that it discriminates against women and that it leads to disposal of normal embryos of the non-desired gender. In this study, the analysis of a large series of PGD procedures for gender selection from a wide geographical area in the USA shows that, in general, there is no deviation in preference towards any specific gender except for a preference of males in some ethnic populations of Chinese, Indian and Middle Eastern origin that represent a small percentage of the US population. In cases where only normal embryos of the non-desired gender are available, 45.5% of the couples elect to cancel the transfer, while 54.5% of them are open to have embryos transferred of the non-desired gender, this fact being strongly linked to cultural and ethnic background of the parents. In addition this study adds some evidence to the proposition that, in couples with previous children of a given gender, there is no biological predisposition towards producing embryos of that same gender. Based on these facts, it seems that objections to gender selection formulated by ethics committees and scientific societies are not well founded.

Monte Carlo evaluation of the convolution/superposition algorithm of Hi-Art tomotherapy in heterogeneous phantoms and clinical cases.

The reliability of the convolution/superposition (C/S) algorithm of the Hi-Art tomotherapy system is evaluated by using the Monte Carlo model TomoPen, which has been already validated for homogeneous phantoms. The study was performed in three stages. First, measurements with EBT Gafchromic film for a 1.25 x 2.5 cm2 field in a heterogeneous phantom consisting of two slabs of polystyrene separated with Styrofoam were compared to simulation results from TomoPen. The excellent agreement found in this comparison justifies the use of TomoPen as the reference for the remaining parts of this work. Second, to allow analysis and interpretation of the results in clinical cases, dose distributions calculated with TomoPen and C/S were compared for a similar phantom geometry, with multiple slabs of various densities. Even in conditions of lack of lateral electronic equilibrium, overall good agreement was obtained between C/S and TomoPen results, with deviations within 3%/2 mm, showing that the C/S algorithm accounts for modifications in secondary electron transport due to the presence of a low density medium. Finally, calculations were performed with TomoPen and C/S of dose distributions in various clinical cases, from large bilateral head and neck tumors to small lung tumors with diameter of < 3 cm. To ensure a "fair" comparison, identical dose calculation grid and dose-volume histogram calculator were used. Very good agreement was obtained for most of the cases, with no significant differences between the DVHs obtained from both calculations. However, deviations of up to 4% for the dose received by 95% of the target volume were found for the small lung tumors. Therefore, the approximations in the C/S algorithm slightly influence the accuracy in small lung tumors even though the C/S algorithm of the tomotherapy system shows very good overall behavior.

Fibronectin modulates osteoblast behavior on Nitinol.

We have previously demonstrated that primary rat osteoclasts behave differently when cultured on austenite and martensite Nitinol. In this study, we coated the two phases of Nitinol with plasma fibronectin and studied if this modifies the proliferation and cell cycle of MC3T3-E1 osteoblasts. The influence of the crystalline structure of Nitinol on the remodeling and conformation of fibronectin was also studied. The results on austenite demonstrated that fibronectin was more strongly remodeled and the cells spread better compared with the martensite phase. Interestingly, the conformation of the protein showed no differences between austenite and martensite. In addition, fibronectin improved cell proliferation in both phases, but the effect of fibronectin coating was stronger on the austenite surface. In addition, in both Nitinol phases, the proportion of cells in the G(1) phase was observed to grow in the presence of fibronectin. This could indicate cell differentiation on Nitinol.

Monte Carlo simulation of helical tomotherapy with PENELOPE.

Helical tomotherapy (HT) delivers intensity-modulated radiation therapy (IMRT) using the simultaneous movement of the couch, the gantry and the binary multileaf collimator (MLC), a procedure that differs from conventional dynamic or step-and-shoot IMRT. A Monte Carlo (MC) simulation of HT in the helical mode therefore requires a new approach. Using validated phase-space files (PSFs) obtained through the MC simulation of the static mode with PENELOPE, an analytical model of the binary MLC, called the 'transfer function' (TF), was first devised to perform the transport of particles through the MLC much faster than time-consuming MC simulation and with no significant loss of accuracy. Second, a new tool, called TomoPen, was designed to simulate the helical mode by rotating and translating the initial coordinates and directions of the particles in the PSF according to the instantaneous position of the machine, transporting the particles through the MLC (in the instantaneous configuration defined by the sinogram), and computing the dose distribution in the CT structure using PENELOPE. Good agreement with measurements and with the treatment planning system of tomotherapy was obtained, with deviations generally well within 2%/1 mm, for the simulation of the helical mode for two commissioning procedures and a clinical plan calculated and measured in homogeneous conditions.

The impact of linac output variations on dose distributions in helical tomotherapy.

It has been suggested for quality assurance purposes that linac output variations for helical tomotherapy (HT) be within +/-2% of the long-term average. Due to cancellation of systematic uncertainty and averaging of random uncertainty over multiple beam directions, relative uncertainties in the dose distribution can be significantly lower than those in linac output. The sensitivity of four HT cases with respect to linac output uncertainties was assessed by scaling both modeled and measured systematic and random linac output uncertainties until a dose uncertainty acceptance criterion failed. The dose uncertainty acceptance criterion required the delivered dose to have at least a 95% chance of being within 2% of the planned dose in all of the voxels in the treatment volume. For a random linac output uncertainty of 5% of the long-term mean, the maximum acceptable amplitude of the modeled, sinusoidal, systematic component of the linac output uncertainty for the four cases was 1.8%. Although the measured linac output variations represented values that were outside of the +/-2% tolerance, the acceptance criterion did not fail for any of the four cases until the measured linac output variations were scaled by a factor of almost three. Thus, the +/-2% tolerance in linac output variations for HT is a more conservative tolerance than necessary.

The denoising of Monte Carlo dose distributions using convolution superposition calculations.

Monte Carlo (MC) dose calculations can be accurate but are also computationally intensive. In contrast, convolution superposition (CS) offers faster and smoother results but by making approximations. We investigated MC denoising techniques, which use available convolution superposition results and new noise filtering methods to guide and accelerate MC calculations. Two main approaches were developed to combine CS information with MC denoising. In the first approach, the denoising result is iteratively updated by adding the denoised residual difference between the result and the MC image. Multi-scale methods were used (wavelets or contourlets) for denoising the residual. The iterations are initialized by the CS data. In the second approach, we used a frequency splitting technique by quadrature filtering to combine low frequency components derived from MC simulations with high frequency components derived from CS components. The rationale is to take the scattering tails as well as dose levels in the high-dose region from the MC calculations, which presumably more accurately incorporates scatter; high-frequency details are taken from CS calculations. 3D Butterworth filters were used to design the quadrature filters. The methods were demonstrated using anonymized clinical lung and head and neck cases. The MC dose distributions were calculated by the open-source dose planning method MC code with varying noise levels. Our results indicate that the frequency-splitting technique for incorporating CS-guided MC denoising is promising in terms of computational efficiency and noise reduction.

Evaluation of a diode array for QA measurements on a helical tomotherapy unit.

A helical tomotherapy system is used in our clinic to deliver intensity-modulated radiation therapy (IMRT) treatments. Since this machine is designed to deliver IMRT treatments, the traditional field flatness requirements are no longer applicable. This allows the unit to operate without a field flatness filter and consequently the 400 mm wide fan beam is highly inhomogeneous in intensity. The shape of this beam profile is mapped during machine commissioning and for quality assurance purposes the shape of the beam profile needs to be monitored. The use of a commercial diode array for quality assurance measurements is investigated. Central axis beam profiles were acquired at different depths using solid water built-up material. These profiles were compared with ion chamber scans taken in a water tank to test the accuracy of the diode array measurements. The sensitivity of the diode array to variations in the beam profile was checked. Over a seven week period, beam profiles were repeatedly measured. The observed variations are compared with those observed with an on-board beam profile monitor. The diode measurements were in agreement with the ion chamber scans. In the high dose, low gradient region the average ratio between the diode and ion chamber readings was 1.000 +/- 0.005 (+/- 1 standard deviation). In the penumbra region the agreement was poorer but all diodes passed the distance to agreement (DTA) requirement of 2 mm. The trend in the beam profile variations that was measured with the diode array device was in agreement with the on-board monitor. While the calculated amount of variation differs between the devices, both were sensitive to subtle variations in the beam profile. The diode array is a valuable tool to quickly and accurately monitor the beam profile on a helical tomotherapy unit.

The use of megavoltage CT (MVCT) images for dose recomputations.

Megavoltage CT (MVCT) images of patients are acquired daily on a helical tomotherapy unit (TomoTherapy, Inc., Madison, WI). While these images are used primarily for patient alignment, they can also be used to recalculate the treatment plan for the patient anatomy of the day. The use of MVCT images for dose computations requires a reliable CT number to electron density calibration curve. In this work, we tested the stability of the MVCT numbers by determining the variation of this calibration with spatial arrangement of the phantom, time and MVCT acquisition parameters. The two calibration curves that represent the largest variations were applied to six clinical MVCT images for recalculations to test for dosimetric uncertainties. Among the six cases tested, the largest difference in any of the dosimetric endpoints was 3.1% but more typically the dosimetric endpoints varied by less than 2%. Using an average CT to electron density calibration and a thorax phantom, a series of end-to-end tests were run. Using a rigid phantom, recalculated dose volume histograms (DVHs) were compared with plan DVHs. Using a deformed phantom, recalculated point dose variations were compared with measurements. The MVCT field of view is limited and the image space outside this field of view can be filled in with information from the planning kVCT. This merging technique was tested for a rigid phantom. Finally, the influence of the MVCT slice thickness on the dose recalculation was investigated. The dosimetric differences observed in all phantom tests were within the range of dosimetric uncertainties observed due to variations in the calibration curve. The use of MVCT images allows the assessment of daily dose distributions with an accuracy that is similar to that of the initial kVCT dose calculation.

The helical tomotherapy thread effect.

Inherent to helical tomotherapy is a dose variation pattern that manifests as a "ripple" (peak-to-trough relative to the average). This ripple is the result of helical beam junctioning, completely unique to helical tomotherapy. Pitch is defined as in helical CT, the couch travel distance for a complete gantry rotation relative to the axial beam width at the axis of rotation. Without scattering or beam divergence, an analytical posing of the problem as a simple integral predicts minima near a pitch of 1/n where n is an integer. A convolution-superposition dose calculator (TomoTherapy, Inc.) included all the physics needed to explore the ripple magnitude versus pitch and beam width. The results of the dose calculator and some benchmark measurements demonstrate that the ripple has sharp minima near p=0.86(1/n). The 0.86 factor is empirical and caused by a beam junctioning of the off-axis dose profiles which differ from the axial profiles as well as a long scatter tail of the profiles at depth. For very strong intensity modulation, the 0.86 factor may vary. The authors propose choosing particular minima pitches or using a second delivery that starts 180 deg off-phase from the first to reduce these ripples: "Double threading." For current typical pitches and beam widths, however, this effect is small and not clinically important for most situations. Certain extremely large field or high pitch cases, however, may benefit from mitigation of this effect.

Quality assurance of a helical tomotherapy machine.

Helical tomotherapy has been developed at the University of Wisconsin, and 'Hi-Art II' clinical machines are now commercially manufactured. At the core of each machine lies a ring-gantry-mounted short linear accelerator which generates x-rays that are collimated into a fan beam of intensity-modulated radiation by a binary multileaf, the modulation being variable with gantry angle. Patients are treated lying on a couch which is translated continuously through the bore of the machine as the gantry rotates. Highly conformal dose-distributions can be delivered using this technique, which is the therapy equivalent of spiral computed tomography. The approach requires synchrony of gantry rotation, couch translation, accelerator pulsing and the opening and closing of the leaves of the binary multileaf collimator used to modulate the radiation beam. In the course of clinically implementing helical tomotherapy, we have developed a quality assurance (QA) system for our machine. The system is analogous to that recommended for conventional clinical linear accelerator QA by AAPM Task Group 40 but contains some novel components, reflecting differences between the Hi-Art devices and conventional clinical accelerators. Here the design and dosimetric characteristics of Hi-Art machines are summarized and the QA system is set out along with experimental details of its implementation. Connections between this machine-based QA work, pre-treatment patient-specific delivery QA and fraction-by-fraction dose verification are discussed.