Introduction of hospital quality measures may lead to a temporary decrease in patient outcomes.

OBJECTIVES: To analyse the impact of hospital quality indicators on hip fracture mortality in Israel. STUDY DESIGN: A retrospective observational study. METHODS: Data were collected on all patients aged ≥65 years with an isolated hip fracture in the years 2010-2016 from the Israel's National Trauma Registry. These data were then cross checked with information on co-morbidities and medication intake from the Clalit medical fund. All successfully matched patients constituted the study population. The main outcome measures were in-hospital and 1-year mortality. Trend analysis of surgery on hip fractures within 48 h of hospitalisation (referred to as early hip fracture surgeries) and mortality was performed. The introduction of the proportion of early hip fracture surgeries as an official quality parameter in 2013 was considered an intervention. RESULTS: The proportion of early hip fracture surgeries continuously increased during the study period and, after the introduction of the quality measure, a significant increase in the uniformity of practice among hospitals was observed. The mortality trend was not related to the early surgeries trend, with a sharp upward spike detected in 2014, followed by a gradual return to previous levels in the subsequent years. The analysis has shown that when adjusting for demographic factors and co-morbidity, both in 2010-2013 and in 2015-2016, a clear benefit in survival existed for patients who were operated on within the first 48 h. In 2014, which was the first year of open publication of achieved quality measures reported in the media, no such benefit was found. CONCLUSIONS: Even when an improvement in a promoted practice is achieved, its positive impact on clinical outcomes may be delayed, possibly indicating the need for a learning period.

Traumatic brain injury: It is all about definition.

BACKGROUND: TBI may be defined by different methods. Some may be most useful for immediate clinical purposes, however less optimal for epidemiologic research. Other methods, such as the Abbreviated Injury Score (AIS), may prove more beneficial for this task, if the cut-off-points for their categories are defined correctly. OBJECTIVE: To reveal the optimal cut-off-points for AIS in definition of severity of TBI in order to ensure uniformity between future studies of TBI. RESULTS: Mortality of patients with TBI AIS 3, 4 was 1.9% and 2.9% respectively, comparing with 31.1% among TBI AIS 5+. Predictive discrimination ability of the model with cut-off-points of 5+ for TBI AIS (in comparison with other cut-off-points) was better. Patients with missing Glasgow Coma Scale (GCS) in the ED had an in-hospital mortality rate of 11.5%. In this group, 25% had critical TBI according to AIS. Normal GCS didn't indicate an absence of head injury, as, among patients with GCS 15 in the ED, 26% had serious/critical TBI injury. Moreover, 7% of patients with multiple injury and GCS 3-8 had another reason than head injury for unconsciousness. CONCLUSIONS: This study recommends the adoption of an AIS cut-off ≥ 5 as a valid definition of severe TBI in epidemiological studies, while AIS 3-4 may be defined as 'moderate' TBI and AIS 1-2 as 'mild'.

Autosomal Dominant Polycystic Kidney Disease and Intracranial Aneurysms: Is There an Increased Risk of Treatment?

BACKGROUND AND PURPOSE: Autosomal dominant polycystic kidney disease is associated with an increased risk of intracranial aneurysms. Our purpose was to assess whether there is an increased risk during aneurysm coiling and clipping. MATERIALS AND METHODS: Data were obtained from the National Inpatient Sample (2000-2011). All subjects had an unruptured aneurysm clipped or coiled and were divided into polycystic kidney (n = 189) and control (n = 3555) groups. Primary end points included in-hospital mortality, length of stay, and total hospital charges. Secondary end points included the International Classification of Diseases, Ninth Revision codes for iatrogenic hemorrhage or infarction; intracranial hemorrhage; embolic infarction; and carotid and vertebral artery dissections. RESULTS: There was a significantly greater incidence of iatrogenic hemorrhage or infarction, embolic infarction, and carotid artery dissection in the patients with polycystic kidney disease compared with the control group after endovascular coiling. There was also a significantly greater incidence of iatrogenic hemorrhage or infarction in the polycystic kidney group after surgical clipping. However, the hospital stay was not longer in the polycystic kidney group, and the total hospital charges were not higher. Additional analysis within the polycystic kidney group revealed a significantly shorter length of stay but similar in-hospital costs when subjects underwent coiling versus clipping. CONCLUSIONS: Patients with polycystic kidney disease face an increased risk during intracranial aneurysm treatment, whether by coiling or clipping. This risk, however, does not translate into longer hospital stays or increased hospital costs. Despite the additional catheterization-related risks of dissection and embolization, coiling results in shorter hospital stays and similar mortality compared with clipping.

Should patients with autosomal dominant polycystic kidney disease be screened for cerebral aneurysms?

Autosomal dominant polycystic kidney disease is a genetic disorder affecting 1 in 1000 people worldwide and is associated with an increased risk of intracranial aneurysms. It remains unclear whether there is sufficient net benefit to screening this patient population for IA, considering recent developments in imaging and treatment and our evolving understanding of the natural history of unruptured aneurysms. There is currently no standardized screening protocol for IA in patients with ADPCKD. Our review of the literature focused on the above issues and presents our appraisal of the estimated value of screening for IA in the setting of ADPCKD.

Percutaneous transosseous translaminar approach for thecal sac access in advanced ankylosing spondylitis with instrumented posterior spinal fusion.

A novel transosseous approach for percutaneous access of the lumbar subarachnoid space is described in a patient with advanced ankylosing spondylitis (AS) and instrumented spinal fusion who presented for myelography. Use of a coaxial threaded bone biopsy system to provide transosseous access to the thecal sac, imaging findings, and outcome are discussed. This technique provided access to an otherwise inaccessible subarachnoid space and is an alternative approach in the setting of advanced AS or posterior spinal fusion.

Uncertainty of calibrations at the accredited dosimetry calibration laboratories.

The American Association of Physicists in Medicine, through a subcommittee (formerly Task Group 3) of the Radiation Therapy Committee, has accredited five laboratories to perform calibrations of instruments used to calibrate therapeutic radiation beams. The role of the accredited dosimetry calibration laboratories (ADCLs) is to transfer a calibration factor from an instrument calibrated by the National Institute of Standards and Technology (NIST) to a customer's instrument. It is of importance to the subcommittee, to physicists using the services of the ADCLs, and to the ADCLs themselves, to know the uncertainty of instrument calibrations. The calibration uncertainty has been analyzed by asking the laboratories to provide information about their calibration procedures. Estimates of uncertainty by two procedures were requested: Type A are uncertainties derived as the standard deviations of repeated measurements, while type B are estimates of uncertainties obtained by other methods, again expressed as standard deviations. Data have been received describing the uncertainty of each parameter involved in calibrations, including those associated with measurements of charge, exposure time, and air density, among others. These figures were combined with the uncertainty of NIST calibrations, to arrive at an overall uncertainty which is expressed at the two-standard deviation level. For cable-connected instruments in gamma-ray and x-ray beams of HVL > 1 mm Al, the figure has an upper bound of approximately 1.2%.

Mechanism of inhibition of fibrinolysis and fibrinogenolysis by the end fibrinogen degradation products.

Influence of the end fibrinogen-derived DH, DL and E fragments on fibrinolysis and fibrinogenolysis has been studied. Electrophoresis of the plasmin-digested unstabilized fibrin and fibrinogen showed that fragment E was the only inhibitor of plasmin hydrolysis of fibrinogen, the antifibrinolytic activity of the fragments being increased in a DL < E < DH series. The fragments were revealed by means of elastic light scattering and analytical ultracentrifugation to be arranged in a E > DL > DH series by their ability to form a complex with plasminogen. It was concluded that the complex formation did not greatly contribute to the mechanism of fibrinolysis inhibition. Antifibrinolytic effect of fragment DH is due to its antipolymerization activity. The paper discusses the competitive protein-protein interactions occurring on a polymeric matrix of fibrin.

Electron dose calculation using multiple-scattering theory: thin planar inhomogeneities.

In this article in our series on electron dose calculation using multiple-scattering theory, we apply the Fermi-Eyges theory to the problem of a thin planar inhomogeneity present in an otherwise-layered medium. We derive expressions for the distribution function P and the location distribution L (which multiplied by the restricted mass collision stopping power is the dose directly deposited by the primary electrons) for various types of incident beams: a completely arbitrary distribution, a Gaussian point source, a pencil beam, an isotropic point source, and a broad parallel beam. We show how divergent-beam dose distributions can be determined from parallel-beam calculations, through use of equivalent configurations dependent upon the depth of dose calculation. Also, we indicate how this work can be applied to the design of wedges (or "compensators") for beam shaping to provide desired dose distributions or to match juxtaposed radiation fields. Explicit formulas for thin plates are then worked out, and we examine the appearance of hot and cold spots distal to the edge of a localized inhomogeneity, for thin half-slabs and for narrow strips. Finally, considering the case of a thin straight wedge-shaped inhomogeneity, we theoretically discover the phenomenon of a "focused hot spot" without an accompanying cold spot, and suggest the design of a "multiple-scattering lens".

Treatment planning with external beams. Introduction and historical overview.

In this first of a series of articles on Radiation Treatment Planning based on the Basic Physics Symposium of the American Association of Physicists in Medicine at the 73rd Annual meeting of the RSNA, an attempt has been made to provide a broad overview of the process of designing an optimal radiation therapy regimen. The essentials of treatment planning have been identified and essential terms have been defined. Variables to be selected have been identified and constraints in choosing treatment plans have been noted. The effect of combining multiple beams to achieve the most advantageous distribution of radiation dose within the patient has been discussed and the vital importance of appropriate quality control has been emphasized. Future articles will consider specific aspects of this discipline in detail.

Collimated electron beams and their associated penumbra widths.

The Fermi-Eyges multiple-scattering theory for electrons is applied to calculate profiles of collimated electron beams. The dose profile below the collimator is a convolution of the intensity distribution of the electrons at the level of the collimator and the distribution arising from the propagation of a Gaussian point source from the collimator to the level of the calculation. The electrons at the level of the collimator possess an angular distribution characteristic of the configuration of the electron beam at the vacuum window. Hence, the dose profile and its associated penumbra width can be expressed in terms of the angular moments of the distribution of the electrons at the collimator. The dependence of the penumbra width on the configuration-dependent angular spread of the electrons at the collimator accounts for differences in the size of the penumbra between two broad-beam configurations. These differences are also seen experimentally. We have also studied the dependence of the angular moments of the electrons upon scattering foils present above the collimator and the position of the beam-broadening device in the accelerator head.

Cylindrical chamber dimensions and the corresponding values of Awall and Ngas/(NxAion).

Cylindrical ionization chamber descriptions and physical dimensions that are necessary for the calculation of Awall and Ngas are presented. Also included are the corresponding calculated values of Awall and Ngas/(NxAion).

Can the AAPM Task Group 21 protocol lead to optimum ion chamber designs?

The recently published AAPM Task Group 21 protocol for high-energy dosimetry is complicated in that it requires the physicist to obtain the values of about a dozen different physical variables by looking them up in tables or graphs. This should be compared with the procedure of earlier protocols using the concept of a single multiplier C lambda. We have investigated how the physical principles outlined in the improved AAPM protocol could be utilized for the redesign of the therapy-level ion chambers in such a way that one can reduce the number of factors that need to be looked up in tables or graphs for the calibration of high-energy teletherapy photon beams. In our analysis presented in this paper we found that one such design could be for an ion chamber having a wall acrylic or Bakelite of a thickness not exceeding 0.1 g/cm2 and having an inner diameter of 6 mm, and used in conjunction with a cobalt-60 buildup cap of thickness 0.35 g/cm2 made of acrylic, Bakelite, or Tufnol. If a chamber of such a design is used in a water phantom, the dosimetry practically reduces to the simplicity of the former protocols of depending on a single value of energy-dependent multiplier to be obtained from a table. With the above design parameters, it becomes possible to eliminate the explicit need to incorporate the factors Pwall, Prepl, Awall, beta wall, and the variable alpha, representing the fraction of ionization due to electrons from the wall material of the chamber.

Quality assurance of radiation dosage: usefulness of redundancy.

Regulations for maintaining the calibration of radiation-measuring instruments generally require that they be recalibrated periodically, and some also specify periodic spot-checks. There is a finite probability that changes in the instrument sensitivity will occur between these calibrations or periodic checks. Routine spot-checks of the output of a therapy unit, made with a given instrument, should detect changes in either device. Comparisons of reliability obtained by these and other procedures for checking on instrument sensitivity are made using calculations based on estimates of the mean time between failures for sources and instruments. These comparisons demonstrate that significantly greater reliability and efficiency should result from considering each machine spot-check and recalibration as a check on the stability of both the machine and the instrument, as opposed to placing complete dependence upon the instrument during the period between separate checks of its sensitivity.

Product representations of teletherapy dose distributions.

Product representations are frequently used for teletherapy dose distributions. For example, the dose in a central plane is often written as the product of two factors, one dependent on the depth and the other on the transverse variable. We have answered the following question: given a (two-dimensional) set of data, how closely is it possible to represent these data by a product of two such factors, and what factors would give a best-fit representation? We thus have developed a quantitative test with which to judge any proposed product representation, for a given set of data. As an example, we have applied our method in analyzing the accuracy of a model proposed by van de Geijn for representing central-plane Cobalt-60 dose data through a product representation on decrement lines intersecting the source.