RESUMO
BACKGROUND: Barriers in access to pediatric surgical care are common in low- and middle-income countries (LMICs), but also exist in high-income countries, particularly in urban and rural areas. METHODS: This article describes "Disparities in Access to Care"-held within the Social Injustice Symposium at the 2020 American Pediatric Surgical Association (APSA) Annual Meeting. RESULTS: This symposium outlined disparities in access to care, illustrated by examples from pediatric trauma and neonatal surgery in U.S. urban, U.S. rural, and non-U.S. global locations (LMICs). Geographic and financial challenges were common to families from the rural U.S. and LMICs. In contrast, families in U.S. urban settings generally do not face geographic barriers, but are often economically and racially diverse and many face complex societal factors leading to poor outcomes. Systemic processes must be changed to improve pediatric surgical health outcomes. CONCLUSION: A comprehensive health system with an equal emphasis on supportive care and surgery is required in all settings. Global collaboration and partnerships can provide an avenue for advocacy and strategic innovation to improve quality of care. LEVEL OF EVIDENCE: â ¤.
Assuntos
Acessibilidade aos Serviços de Saúde , Disparidades em Assistência à Saúde , Renda , Criança , Humanos , Recém-Nascido , Pobreza , População Rural , População Urbana , Características de ResidênciaAssuntos
COVID-19/prevenção & controle , Planejamento em Desastres/métodos , Emergências , Saúde Pública/métodos , Medição de Risco/métodos , SARS-CoV-2/isolamento & purificação , COVID-19/epidemiologia , COVID-19/virologia , Planejamento em Desastres/economia , Planejamento em Desastres/organização & administração , Humanos , Pandemias/prevenção & controle , Saúde Pública/economia , Medição de Risco/economia , Fatores de Risco , SARS-CoV-2/genética , SARS-CoV-2/fisiologiaRESUMO
BACKGROUND: Allocation of scarce resources during a pandemic extends to the allocation of vaccines when they eventually become available. We describe a framework for priority vaccine allocation that employed a cross-disciplinary approach, guided by ethical considerations and informed by local risk assessment. METHODS: Published and grey literature was reviewed, and augmented by consultation with key informants, to collate past experience, existing guidelines and emerging strategies for pandemic vaccine deployment. Identified ethical issues and decision-making processes were also included. Concurrently, simulation modelling studies estimated the likely impacts of alternative vaccine allocation approaches. Assembled evidence was presented to a workshop of national experts in pandemic preparedness, vaccine strategy, implementation and ethics. All of this evidence was then used to generate a proposed ethical framework for vaccine priorities best suited to the Australian context. FINDINGS: Published and emerging guidance for priority pandemic vaccine distribution differed widely with respect to strategic objectives, specification of target groups, and explicit discussion of ethical considerations and decision-making processes. Flexibility in response was universally emphasised, informed by real-time assessment of the pandemic impact level, and identification of disproportionately affected groups. Model outputs aided identification of vaccine approaches most likely to achieve overarching goals in pandemics of varying transmissibility and severity. Pandemic response aims deemed most relevant for an Australian framework were: creating and maintaining trust, promoting equity, and reducing harmful outcomes. INTERPRETATION: Defining clear and ethically-defendable objectives for pandemic response in context aids development of flexible and adaptive decision support frameworks and facilitates clear communication and engagement activities.
Assuntos
Pandemias , Vacinas , Austrália/epidemiologia , Pandemias/prevenção & controle , Alocação de Recursos , ConfiançaRESUMO
BACKGROUND: Pandemic planning has historically been oriented to respond to an influenza virus, with vaccination strategy being a key focus. As the current COVID-19 pandemic plays out, the Australian government is closely monitoring progress towards development of SARS-CoV2 vaccines as a definitive intervention. However, as in any pandemic, initial supply will likely be exceeded by demand due to limited manufacturing output. METHODS: We convened community juries in three Australian locations in 2019 to assess public acceptability and perceived legitimacy of influenza pandemic vaccination distribution strategies. Preparatory work included literature reviews on pandemic vaccine allocation strategies and on vaccine allocation ethics, and simulation modelling studies. We assumed vaccine would be provided to predefined priority groups. Jurors were then asked to recommend one of two strategies for distributing remaining early doses of vaccine: directly vaccinate people at higher risk of adverse outcomes from influenza; or indirectly protect the general population by vaccinating primary school students, who are most likely to spread infection. RESULTS: Thirty-four participants of diverse backgrounds and ages were recruited through random digit dialling and topic-blinded social media advertising. Juries heard evidence and arguments supporting different vaccine distribution strategies, and questioned expert presenters. All three community juries supported prioritising school children for influenza vaccination (aiming for indirect protection), one by 10-2 majority and two by consensus. Justifications included that indirect protection benefits more people and is likely to be more publicly acceptable. CONCLUSIONS: In the context of an influenza pandemic, informed citizens were not opposed to prioritising groups at higher risks of adverse outcomes, but if resources and epidemiological conditions allow, achieving population benefits should be a strategic priority. These insights may inform future SARS-CoV-2 vaccination strategies.
Assuntos
COVID-19/epidemiologia , Alocação de Recursos para a Atenção à Saúde/organização & administração , Programas de Imunização/organização & administração , Vacinas contra Influenza/provisão & distribuição , Influenza Humana/prevenção & controle , Pandemias/prevenção & controle , Vacinação/ética , Adolescente , Adulto , Austrália/epidemiologia , Criança , Feminino , Humanos , Esquemas de Imunização , Vacinas contra Influenza/administração & dosagem , Vacinas contra Influenza/economia , Influenza Humana/epidemiologia , Influenza Humana/imunologia , Influenza Humana/virologia , Masculino , Pessoa de Meia-Idade , Orthomyxoviridae/imunologia , Saúde Pública/economia , Saúde Pública/métodos , SARS-CoV-2/patogenicidade , Vacinação/economia , Cobertura Vacinal/estatística & dados numéricosRESUMO
BACKGROUND: Single visit surgery (SVS) consists of same-day pre-operative assessment and operation with telephone post-operative follow-up. This reduces family time commitment to 1 hospital trip rather than 2-3. We began SVS for ambulatory patients with clear surgical indications in 2013. We sought to determine family satisfaction, cost savings to families, and institutional financial feasibility of SVS. METHODS: SVS patients were compared to age/case matched conventional surgery (CS) patients. Satisfaction was assessed by post-operative telephone survey. Family costs were calculated as the sum of lost revenue (based on median income) and transportation costs ($0.50/mile). RESULTS: Satisfaction was high in both groups (98% for SVS vs. 93% for CS; p=0.27). 40% of CS families indicated that they would have preferred SVS, whereas no SVS families indicated preference for the CS option (p<0.001). Distance from the hospital did not correlate with satisfaction. Estimated cost savings for an SVS family was $188. Reimbursement, hospital and physician charges, and day-of-surgery cancellation rates were similar. CONCLUSIONS: SVS provides substantial cost savings to families while maintaining patient satisfaction and equivalent institutional reimbursement. SVS is an effective approach to low-risk ambulatory surgical procedures that is less disruptive to families, facilitates access to pediatric surgical care, and reduces resource utilization. TYPE OF STUDY: Cost Effectiveness Study. LEVEL OF EVIDENCE: Level II.
RESUMO
Climate change is a risk management challenge for society, with uncertain but potentially severe outcomes affecting natural and human systems, across generations. Managing climate-related risks will be more difficult without a base of knowledge and practice aimed at identifying and evaluating specific risks, and their likelihood and consequences, as well as potential actions to promote resilience in the face of these risks. We suggest three improvements to the process of conducting climate change assessments to better characterize risk and inform risk management actions.
RESUMO
IMPORTANCE: Current evidence suggests that nonoperative management of uncomplicated appendicitis is safe, but overall effectiveness is determined by combining medical outcomes with the patient's and family's perspective, goals, and expectations. OBJECTIVE: To determine the effectiveness of patient choice in nonoperative vs surgical management of uncomplicated acute appendicitis in children. DESIGN, SETTING, AND PARTICIPANTS: Prospective patient choice cohort study in patients aged 7 to 17 years with acute uncomplicated appendicitis presenting at a single pediatric tertiary acute care hospital from October 1, 2012, through March 6, 2013. Participating patients and families gave informed consent and chose between nonoperative management and urgent appendectomy. INTERVENTIONS: Urgent appendectomy or nonoperative management entailing at least 24 hours of inpatient observation while receiving intravenous antibiotics and, on demonstrating improvement of symptoms, completion of 10 days of treatment with oral antibiotics. MAIN OUTCOMES AND MEASURES: The primary outcome was the 1-year success rate of nonoperative management. Successful nonoperative management was defined as not undergoing an appendectomy. Secondary outcomes included comparisons of the rates of complicated appendicitis, disability days, and health care costs between nonoperative management and surgery. RESULTS: A total of 102 patients were enrolled; 65 patients/families chose appendectomy (median age, 12 years; interquartile range [IQR], 9-13 years; 45 male [69.2%]) and 37 patients/families chose nonoperative management (median age, 11 years; IQR, 10-14 years; 24 male [64.9%]). Baseline characteristics were similar between the groups. The success rate of nonoperative management was 89.2% (95% CI, 74.6%-97.0%) at 30 days (33 of 37 children) and 75.7% (95% CI, 58.9%-88.2%) at 1 year (28 of 37 children). The incidence of complicated appendicitis was 2.7% in the nonoperative group (1 of 37 children) and 12.3% in the surgery group (8 of 65 children) (P = .15). After 1 year, children managed nonoperatively compared with the surgery group had fewer disability days (median [IQR], 8 [5-18] vs 21 [15-25] days, respectively; P < .001) and lower appendicitis-related health care costs (median [IQR], $4219 [$2514-$7795] vs $5029 [$4596-$5482], respectively; P = .01). CONCLUSIONS AND RELEVANCE: When chosen by the family, nonoperative management is an effective treatment strategy for children with uncomplicated acute appendicitis, incurring less morbidity and lower costs than surgery. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01718275.
Assuntos
Antibacterianos/uso terapêutico , Apendicite/tratamento farmacológico , Apendicite/cirurgia , Participação do Paciente , Preferência do Paciente , Adolescente , Combinação Amoxicilina e Clavulanato de Potássio/uso terapêutico , Antibacterianos/administração & dosagem , Apendicectomia , Apendicite/complicações , Apendicite/economia , Criança , Ciprofloxacina/uso terapêutico , Família , Feminino , Custos de Cuidados de Saúde , Humanos , Laparoscopia , Masculino , Metronidazol/uso terapêutico , Ácido Penicilânico/análogos & derivados , Ácido Penicilânico/uso terapêutico , Piperacilina/uso terapêutico , Combinação Piperacilina e Tazobactam , Estudos Prospectivos , Resultado do TratamentoRESUMO
PURPOSE: We implemented and validated a linkage algorithm for cases in both the National Surgical Quality Improvement Program-Pediatric (NSQIP-Peds) and the Pediatric Health Information System (PHIS) to investigate healthcare utilization during the first post-operative year. METHODS: NSQIP-Peds and PHIS cases from our institution who were operated on between January 2010 and September 2011 were matched on gender and dates of birth, admission, and discharge. Rates of true matches were validated using medical records. We examined rates of emergency department (ED) visits, hospital readmissions, potentially preventable readmissions (PPR), and hospital charges within one year of the NSQIP-Peds encounter. RESULTS: Of the 2,409 NSQIP-Peds and 61,147 PHIS records, 93.6% met match criteria with 92.5% being true matches. Post-operative ED visit rates were 7.8% within 30days, 17.2% between 31-180days, and 18.1% between 181-365days. Readmission rates were 5.5% within 30days, 9.3% between 31-180days, and 8.4% between 181-365days. In patients undergoing inpatient procedures, 10.6% had readmissions within 30days, and 23.7% had readmissions within 365days that were potentially preventable. CONCLUSIONS: Using indirect identifiers, a linked NSQIP-Peds-PHIS dataset demonstrated high rates of ED visits, readmissions, and PPR in the first post-operative year. This dataset may provide a more comprehensive way to study health care utilization and clinical outcomes.
Assuntos
Bases de Dados Factuais/estatística & dados numéricos , Sistemas de Informação em Saúde/organização & administração , Recursos em Saúde/estatística & dados numéricos , Registro Médico Coordenado , Aceitação pelo Paciente de Cuidados de Saúde/estatística & dados numéricos , Pediatria/organização & administração , Período Pós-Operatório , Melhoria de Qualidade/organização & administração , Especialidades Cirúrgicas/organização & administração , Benchmarking , Criança , Pré-Escolar , Serviço Hospitalar de Emergência/estatística & dados numéricos , Feminino , Preços Hospitalares/estatística & dados numéricos , Registros Hospitalares , Humanos , Lactente , Recém-Nascido , Masculino , Readmissão do Paciente/estatística & dados numéricos , Pediatria/estatística & dados numéricos , Especialidades Cirúrgicas/estatística & dados numéricosRESUMO
PURPOSE: The American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) provides validated assessment of surgical outcomes. This study reports initiation of an ACS NSQIP Pediatric at 4 children's hospitals. METHODS: From October 2008 to June 2009, 121 data variables were prospectively collected for 3315 patients, including 30-day outcomes and tailoring the ACS NSQIP methodology to children's surgical specialties. RESULTS: Three hundred seven postoperative complications/occurrences were detected in 231 patients representing 7.0% of the study population. Of the patients with complications, 175 (75.7%) had 1, 39 (16.9%) had 2, and 17 (7.4%) had 3 or more complications. There were 13 deaths (0.39%) and 14 intraoperative occurrences (0.42%) detected. The most common complications were infection, 105 (34%) (SSI, 54; sepsis, 31; pneumonia, 13; urinary tract infection, 7); airway/respiratory events, 27 (9%); wound disruption, 18 (6%); neurologic events, 8 (3%) (nerve injury, 4; stroke/vascular event, 2; hemorrhage, 2); deep vein thrombosis, 3 (<1%); renal failure, 3 (<1%); and cardiac events, 3 (<1%). Current sampling captures 17.5% of cases across institutions with unadjusted complication rates ranging from 6.8% to 10.2%. Completeness of data collection for all variables exceeded 95% with 98% interrater reliability and 87% of patients having full 30-day follow-up. CONCLUSION: These data represent the first multiinstitutional prospective assessment of specialty-specific surgical outcomes in children. The ACS NSQIP Pediatric is poised for institutional expansion and future development of risk-adjusted models.
Assuntos
Avaliação de Resultados em Cuidados de Saúde/métodos , Pediatria/normas , Melhoria de Qualidade/normas , Sociedades Médicas/normas , Especialidades Cirúrgicas/normas , Adulto , Benchmarking/métodos , Criança , Estudos de Viabilidade , Feminino , Hospitais Pediátricos , Hospitais de Veteranos/normas , Humanos , Masculino , Avaliação de Resultados em Cuidados de Saúde/normas , Pediatria/estatística & dados numéricos , Complicações Pós-Operatórias/epidemiologia , Estudos Prospectivos , Garantia da Qualidade dos Cuidados de Saúde/métodos , Garantia da Qualidade dos Cuidados de Saúde/normas , Especialidades Cirúrgicas/estatística & dados numéricos , Resultado do Tratamento , Estados UnidosRESUMO
OBJECTIVE: Caring for neonates with major congenital anomalies has significant financial implications for the treating institution, which can be positive or negative depending on whether the patient has insurance. We hypothesized that insured affected neonates born in non-children's hospitals would be more likely to be treated on site, whereas uninsured neonates would be more likely to be transferred. PATIENTS AND METHODS: We used the Kids' Inpatient Database to study neonates with congenital anomalies who were born in US non-children's hospitals. We performed bivariate analysis using the chi(2) test and adjusted for covariates with multiple logistic regression. RESULTS: Uninsured patients were 2.57 (95% confidence interval, 1.83-3.62) times more likely to be transferred compared with patients with private insurance or Medicaid, after adjusting for patient and hospital characteristics. This trend increased over time between 1997 and 2006. CONCLUSIONS: The current reimbursement structure in the United States incentivizes non-children's hospitals to retain insured patients with congenital anomalies and transfer uninsured patients with these same anomalies. This places a disproportionate financial burden on children's hospitals while paradoxically causing insured infants to be cared for at hospitals that may not be best equipped to provide complex care.
Assuntos
Anormalidades Congênitas/cirurgia , Acessibilidade aos Serviços de Saúde/economia , Hospitalização/economia , Cobertura do Seguro/estatística & dados numéricos , Seguro Saúde , Parede Abdominal/anormalidades , Parede Abdominal/cirurgia , Anormalidades Congênitas/economia , Economia Hospitalar , Feminino , Custos de Cuidados de Saúde/estatística & dados numéricos , Acessibilidade aos Serviços de Saúde/estatística & dados numéricos , Hospitalização/estatística & dados numéricos , Hospitais Pediátricos/economia , Humanos , Lactente , Recém-Nascido , Seguro Saúde/economia , Unidades de Terapia Intensiva Neonatal/economia , Masculino , Medicaid/economia , Pessoas sem Cobertura de Seguro de Saúde/estatística & dados numéricos , Transferência de Pacientes/economia , Reembolso de Incentivo/economia , Fatores Socioeconômicos , Estados UnidosRESUMO
BNCT treatment planning can be improved by having the adjoint technique available in the Monte Carlo transport code. In adjoint MC, the simulated particles travel backwards instead of 'forward'. By speeding up the calculations, more beam positions can be investigated and thus a better plan can be composed. In a realistic head phantom with 10 disseminated lesions in the brain, the adjoint method is more favourable than the forward calculations whenever larger beam diameters are applied.
Assuntos
Terapia por Captura de Nêutron de Boro/estatística & dados numéricos , Neoplasias Encefálicas/radioterapia , Cabeça , Imagens de Fantasmas/estatística & dados numéricos , Planejamento da Radioterapia Assistida por Computador/estatística & dados numéricos , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/secundário , Humanos , Melanoma/patologia , Melanoma/radioterapia , Melanoma/secundário , Método de Monte CarloRESUMO
At the boron neutron capture therapy (BNCT) facility in Petten, the Netherlands, (10)B concentrations in biological materials are measured with the prompt gamma ray analyses facility that is calibrated using certified (10)B solutions ranging from 0 to 210 ppm. For this study, newly certified (10)B solutions ranging up to 1972 ppm are added. MCNP simulations of the setup range to 5000 ppm. A second order polynomial (as already used) will fit (10)B-concentrations less than 300 ppm. Above 300 ppm a fitted third order polynomial is needed to describe the calibration curve accurately.
Assuntos
Terapia por Captura de Nêutron de Boro/normas , Boro/análise , Espectrometria gama/normas , Boro/uso terapêutico , Terapia por Captura de Nêutron de Boro/instrumentação , Terapia por Captura de Nêutron de Boro/estatística & dados numéricos , Arquitetura de Instituições de Saúde , Raios gama/uso terapêutico , Humanos , Isótopos/análise , Isótopos/uso terapêutico , Modelos Estatísticos , Método de Monte Carlo , Neoplasias/metabolismo , Neoplasias/radioterapia , Países Baixos , Reatores Nucleares , Padrões de Referência , Espectrometria gama/instrumentação , Espectrometria gama/estatística & dados numéricos , Distribuição TecidualRESUMO
BNCT causes selective damage to tumor cells by neutron capture reactions releasing high LET-particles where (10)B-atoms are present. Neither the (10)B-compound nor thermal neutrons alone have any therapeutic effect. Therefore, the development of BNCT to a treatment modality needs strategies, which differ from the standard phase I-III clinical trials. An innovative trial design was developed including translational research and a phase I aspect. The trial investigates as surrogate endpoint BSH and BPA uptake in different tumor entities.
Assuntos
Terapia por Captura de Nêutron de Boro/métodos , Neoplasias/radioterapia , Adenocarcinoma/metabolismo , Adenocarcinoma/radioterapia , Adenocarcinoma/secundário , Boroidretos/farmacocinética , Boroidretos/uso terapêutico , Compostos de Boro/farmacocinética , Compostos de Boro/uso terapêutico , Carcinoma de Células Escamosas/metabolismo , Carcinoma de Células Escamosas/radioterapia , Neoplasias Colorretais , Feminino , Neoplasias de Cabeça e Pescoço/metabolismo , Neoplasias de Cabeça e Pescoço/radioterapia , Humanos , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/radioterapia , Neoplasias Hepáticas/secundário , Masculino , Neoplasias/metabolismo , Fenilalanina/análogos & derivados , Fenilalanina/farmacocinética , Fenilalanina/uso terapêutico , Estudos Prospectivos , Radiossensibilizantes/farmacocinética , Radiossensibilizantes/uso terapêutico , Compostos de Sulfidrila/farmacocinética , Compostos de Sulfidrila/uso terapêutico , Neoplasias da Glândula Tireoide/metabolismo , Neoplasias da Glândula Tireoide/radioterapia , Distribuição TecidualRESUMO
A Monte Carlo calculation was carried out for boron neutron capture therapy (BNCT) of extra corporal liver phantom. The present paper describes the basis for a subsequent clinical application of the prompt gamma spectroscopy set-up aimed at in vivo monitoring of boron distribution. MCNP code was used first to validate the homogeneity in thermal neutron field in the liver phantom and simulate the gamma ray detection system (collimator and detector) in the treatment room. The gamma ray of 478 keV emitted by boron in small specific region can be detected and a mathematical formalism was used for the tomography image reconstruction.
Assuntos
Terapia por Captura de Nêutron de Boro/métodos , Boro/farmacocinética , Boro/uso terapêutico , Neoplasias Hepáticas/radioterapia , Neoplasias Hepáticas/secundário , Espectrometria gama/métodos , Terapia por Captura de Nêutron de Boro/estatística & dados numéricos , Nêutrons Rápidos/uso terapêutico , Humanos , Processamento de Imagem Assistida por Computador/métodos , Processamento de Imagem Assistida por Computador/estatística & dados numéricos , Técnicas In Vitro , Modelos Estatísticos , Método de Monte Carlo , Países Baixos , Imagens de Fantasmas/estatística & dados numéricos , Espectrometria gama/estatística & dados numéricosRESUMO
For an accurate determination of the absorbed doses in complex radiation fields (e.g. mixed neutron-gamma fields), a better interpretation of the response of ionisation chambers is required. This study investigates a model of the ionisation chambers using a different approach, analysing the collected charge per minute as a response of the detector instead of the dose. The MCNPX Monte Carlo code is used. In this paper, the model is validated using a well-known irradiation field only: a (60)Co source. The detailed MCNPX models of a Mg(Ar) and TE(TE) ionisation chamber is investigated comparing the measured charge per minute obtained free-in-air and in a water phantom with the simulated results. The difference between the calculations and the measurements for the TE(TE) chamber is within +/-2% whereas for the Mg(Ar) chamber is around +7%. The systematic discrepancy in the case of Mg(Ar) chamber is expected to be caused by an overestimation of the sensitive volume.
Assuntos
Argônio/química , Radioisótopos de Cobalto , Raios gama , Magnésio/química , Radiometria/instrumentação , Telúrio/química , Método de Monte Carlo , NêutronsRESUMO
The aim of this study is to introduce a triple ionization chamber system to separate dose components of mixed neutron/photon fields. Fast and thermal neutron dose components have a different biological effectiveness than gamma dose components. If boron neutron capture is used to enhance the dose in certain areas of a patient, the precise knowledge of the thermal neutron flux is essential. A tissue equivalent and two magnesium ionization chambers have been prepared for use in a triple chamber system for this purpose. One of the magnesium chambers is coated with (10)B on the inside to enhance its response to thermal neutrons. All three chambers have been calibrated at a cobalt source, medical linear accelerators and several neutron sources. The chambers have been studied in Monte Carlo simulations and the results are compared with measurements.
Assuntos
Terapia por Captura de Nêutron de Boro/métodos , Radiometria/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Terapia por Captura de Nêutron de Boro/instrumentação , Calibragem , Cobalto/química , Radioisótopos de Cobalto/química , Humanos , Íons , Magnésio/química , Método de Monte Carlo , Nêutrons , Imagens de Fantasmas , Fótons , Dosagem RadioterapêuticaRESUMO
This paper deals with the application of the adjoint transport theory in order to optimize Monte Carlo based radiotherapy treatment planning. The technique is applied to Boron Neutron Capture Therapy where most often mixed beams of neutrons and gammas are involved. In normal forward Monte Carlo simulations the particles start at a source and lose energy as they travel towards the region of interest, i.e., the designated point of detection. Conversely, with adjoint Monte Carlo simulations, the so-called adjoint particles start at the region of interest and gain energy as they travel towards the source where they are detected. In this respect, the particles travel backwards and the real source and real detector become the adjoint detector and adjoint source, respectively. At the adjoint detector, an adjoint function is obtained with which numerically the same result, e.g., dose or flux in the tumor, can be derived as with forward Monte Carlo. In many cases, the adjoint method is more efficient and by that is much quicker when, for example, the response in the tumor or organ at risk for many locations and orientations of the treatment beam around the patient is required. However, a problem occurs when the treatment beam is mono-directional as the probability of detecting adjoint Monte Carlo particles traversing the beam exit (detector plane in adjoint mode) in the negative direction of the incident beam is zero. This problem is addressed here and solved first with the use of next event estimators and second with the application of a Legendre expansion technique of the angular adjoint function. In the first approach, adjoint particles are tracked deterministically through a tube to a (adjoint) point detector far away from the geometric model. The adjoint particles will traverse the disk shaped entrance of this tube (the beam exit in the actual geometry) perpendicularly. This method is slow whenever many events are involved that are not contributing to the point detector, e.g., neutrons in a scattering medium. In the second approach, adjoint particles that traverse an adjoint shaped detector plane are used to estimate the Legendre coefficients for expansion of the angular adjoint function. This provides an estimate of the adjoint function for the direction normal to the detector plane. In a realistic head model, as described in this paper, which is surrounded by 1020 mono-directional neutron/gamma beams and from which the best ones are to be selected, the example calculates the neutron and gamma fluxes in ten tumors and ten organs at risk. For small diameter beams (5 cm), and with comparable relative errors, forward Monte Carlo is seen to be 1.5 times faster than the adjoint Monte Carlo techniques. For larger diameter neutron beams (10 and 15 cm), the Legendre technique is found to be 6 and 20 times faster, respectively. In the case of gammas alone, for the 10 and 15 cm diam beams, both adjoint Monte Carlo Legendre and point detector techniques are respectively 2 and 3 times faster than forward Monte Carlo.
Assuntos
Algoritmos , Terapia por Captura de Nêutron de Boro/métodos , Modelos Biológicos , Método de Monte Carlo , Radiometria/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Simulação por Computador , Humanos , Modelos Estatísticos , Dosagem RadioterapêuticaRESUMO
BACKGROUND/PURPOSE: The aim of this study was to determine the preliminary impact of work hour regulations on pediatric surgical training. METHODS: An anonymous survey was sent to all program directors (PDs) and fellows to identify changes in pediatric surgery fellowship programs. RESULTS: Ninety-three percent of programs and 87% of PDs responded. Thirty programs hired additional personnel, including nurse practitioners, physician assistants, and fellows outside the training program. Thirteen programs reported increased attending coverage. The daily composition of the surgical team has changed, with postcall fellows and residents leaving in the morning. Residents and fellows also take call less frequently. More than 50% of PDs felt that quality of care had declined and three quarters of respondents felt that continuity of care was worse. Half of the respondents feared missed educational opportunities. However, half of the fellows felt more rested, 61% reported more family time, and 22% reported increased social time. In contrast, no PDs perceived life-style improvements. CONCLUSIONS: The work hour regulations have resulted in fundamental changes in pediatric surgical training. Ongoing assessment is needed to prioritize quality of care, improve continuity of care, and track changes in operative, clinical, and didactic experiences of the trainees. The added impact of these changes on the time spent available for commitment to teaching by the faculty should be assessed.
Assuntos
Atitude do Pessoal de Saúde , Educação de Pós-Graduação em Medicina/organização & administração , Pediatria/educação , Admissão e Escalonamento de Pessoal/normas , Diretores Médicos/psicologia , Qualidade da Assistência à Saúde/tendências , Especialidades Cirúrgicas/educação , Centro Cirúrgico Hospitalar , Criança , Connecticut , Continuidade da Assistência ao Paciente/tendências , Bolsas de Estudo/organização & administração , Pesquisas sobre Atenção à Saúde , Humanos , Inovação Organizacional , Centro Cirúrgico Hospitalar/organização & administração , Fatores de Tempo , Recursos HumanosRESUMO
The values of the parameters used in boron neutron capture therapy (BNCT) to calculate a given dose to human tissue vary with patients due to different physical, biological and/or medical circumstances. Parameters include the tissue dimensions, the 10B concentration and the relative biological effectiveness (RBE) factors for the different dose components associated with BNCT. Because there is still no worldwide agreement on RBE values, more often than not, average values for these parameters are used. It turns out that the RBE-problem can be circumvented by taking into account all imaginable parameter values. Approaching this quest from another angle: the outcome will also provide the parameters (and values) which influence the optimal source neutron energy. For brain tumours it turns out that the 10B concentration, the RBE factors for 10B as well as fast neutrons, together with the dose limit set for healthy tissue, affect the optimal BNCT source neutron energy. By using source neutrons of a few keV together with neutrons of a few eV, it ensures that, under all imaginable circumstances, a maximum of alpha (and lithium) particles can be delivered in the tumour.