Determination of the accuracy of implant reconstruction and dose delivery in brachytherapy in The Netherlands and Belgium

Purpose: To gain insight into the accuracy of brachytherapy treatments, the accuracy of implant reconstruction and dose delivery was investigated in 33 radiotherapy institutions in The Netherlands and Belgium. Materials and methods: The accuracy of the implant reconstruction method was determined using a cubic phantom containing 25 spheres at well-known positions. Reconstruction measurements were obtained on 41 brachytherapy localizers, 33 of which were simulators. The reconstructed distances between the spheres were compared with the true distances. The accuracy of the dose delivery was determined for high dose rate (HDR), pulsed dose rate (PDR) and low dose rate (LDR) afterloading systems using a polymethyl methacrylate cylindrical phantom containing a NE 2571 ionization chamber in its centre. The institutions were asked to deliver a prescribed dose at the centre of the phantom. The measured dose was compared with the prescribed dose. Results: The average reconstruction accuracy was -0.07 mm (±0.4 mm, 1 SD) for 41 localizers. The average deviation of the measured dose from the prescribed dose was +0.9% (±1.3%, 1 SD) for 21 HDR afterloading systems, +1.0% (±2.3%, 1 SD) for 12 PDR afterloaders, and +1.8% (±2.5%, 1 SD) for 15 LDR afterloaders. Conclusions: This comparison showed a good accuracy of brachytherapy implant reconstruction and dose delivery in The Netherlands and Belgium

Clinical characteristics of women captured by extending the definition of severe postpartum haemorrhage with 'refractoriness to treatment': a cohort study

Background: The absence of a uniform and clinically relevant definition of severe postpartum haemorrhage hampers comparative studies and optimization of clinical management. The concept of persistent postpartum haemorrhage, based on refractoriness to initial first-line treatment, was proposed as an alternative to common definitions that are either based on estimations of blood loss or transfused units of packed red blood cells (RBC). We compared characteristics and outcomes of women with severe postpartum haemorrhage captured by these three types of definitions. Methods: In this large retrospective cohort study in 61 hospitals in the Netherlands we included 1391 consecutive women with postpartum haemorrhage who received either ≥4 units of RBC or a multicomponent transfusion. Clinical characteristics and outcomes of women with severe postpartum haemorrhage defined as persistent postpartum haemorrhage were compared to definitions based on estimated blood loss or transfused units of RBC within 24 h following birth. Adverse maternal outcome was a composite of maternal mortality, hysterectomy, arterial embolisation and intensive care unit admission. Results: One thousand two hundred sixty out of 1391 women (90.6%) with postpartum haemorrhage fulfilled the definition of persistent postpartum haemorrhage. The majority, 820/1260 (65.1%), fulfilled this definition within 1 h following birth, compared to 819/1391 (58.7%) applying the definition of ≥1 L blood loss and 37/845 (4.4%) applying the definition of ≥4 units of RBC. The definition persistent postpartum haemorrhage captured 430/471 adverse maternal outcomes (91.3%), compared to 471/471 (100%) for ≥1 L blood loss and 383/471 (81.3%) for ≥4 units of RBC. Persistent postpartum haemorrhage did not capture all adverse outcomes because of missing data on timing of initial, first-line treatment. Conclusion: The definition persistent postpartum haemo

Consistency in quality control programmes for electron accelerators in radiotherapy centres

Background and purpose: To gain insight into the current practice of quality control (QC) of medical electron accelerators and to reduce possible variations in test frequencies and test procedures. Materials and methods: An extensive questionnaire on QC procedures of medical electron accelerators was distributed and completed by all (21) radiotherapy institutions in The Netherlands. The questions were related to safety systems, mechanical parameters, beam profiles, beam energy, absolute dosimetry, wedge filters, the dose monitor system and radiation leakage. Results: The data of the questionnaire were compared with recommendations given in national and international reports on QC of electron accelerators. Large variations in time spent on QC exist, especially for accelerators having dual energy photon beams and several electron beam energies. This diversity is mainly due to differences in philosophy with regard to QC and the differences in resources and machine time available. Furthermore, large variations in test frequencies and test methodologies were observed. The staffing level involved in the QC measurements was evaluated and compared with recent recommendations provided by EFOMP-ESTRO. Conclusions: From these recommendations and the results of the questionnaire, a set of minimum guidelines for a QC programme could be formulated and implemented in all radiotherapy institutions in The Netherlands

Lees eerst de bijsluiter : het in gebruik nemen van nieuwe medische apparatuur

Als nieuwe apparatuur en methoden in de gezondheidszorg worden toegepast, zijn er extra risico's dat er ongelukken optreden - een voorbeeld is de ingebruikname van een autoloog infuussysteem. Om deze risico's te minimaliseren zijn enkele maatregelen vereist: blamefree rapportage van (bijna-)incidenten en ongevallen; het instellen van een veiligheidskern in ieder ziekenhuis; het toepassen van in de industrie ontwikkelde strategieën op het gebied van veiligheidskunde en risicoanalyse zoals die aan klinisch fysici voor de gezondheidszorg zijn onderwezen ter preventie

Axillary recurrence after negative sentinel lymph node biopsy: Frequency and factors influencing recurrence on the long term

Table S1. Primers used in the study. Figure S1. Plasmid construct developed and used for the genetic complementation of E. tenella. The plasmids contain a double cassette: mCitrine - green arrow - flanked by 5′EtMIC1 and 3′EtMIC1 - green arrows - and EtMIC2 and EtMCP2 fused to mCherry - yellow arrow + red arrow - flanked by 5′EtMIC2 and 3′EtMIC3 - final purple arrows. (PDF 273 kb

Determination and use of scatter correction factors of megavoltage photon beams: Measurement and use of collimator and phantom scatter correction factors of arbitrarily shaped fiels with a symmetrical collimator setting

For each radiation treatment machine, the dose per monitor unit must be known at a reference point in a water-phantom under reference conditions. It varies with field size, due to: ( 1) changes in radiation scattered from the head of the treatment machine to the reference point and into the monitor chamber and ( 2) changes in the radiation scattered from the irradiated part of the phantom to the reference point. The field size dependence is usually described by the total scatter correction factor, Scp• If the field size defined by the collimator setting at the reference source-surface distance ( SSD) does not correspond with the field size at the phantom surface, Sec must be separated into two factors, the head or collimator scatter correction factor, Sc, and the phantom scatter correction factor, Sc. This is the case when a source-surface distance different from the SSD of the reference condition is used, when tissue is missing in the beam, or when shielding blocks are applied. The factor Sc describes the influence of the setting of the collimator on the total scatter correction factor; Sp describes the influence of the field size at the phantom surface, and thus of the irradiated volume on this correction f actor. In this report, recommendations are given for the measurement of Scp, Sc and Sp in a photon beam at a reference depth of 10 cm. The reference field is defined as the open field, with a collimator setting yielding a 10 cm x 10 cm field when the SSD is set equal to the source-axis distance ( SAD) . For the determination of Sc, the use of a narrow cylindrical beam-coaxial phantom (the mini-phantom) is recommended. In this way, measurements can be performed in small fields and the disturbance of contaminating electrons, reaching the point of interest from the head of the treatment machine, becomes negligible. Construction details of the mini-phantom are described. Furthermore, a consistent set of relations is presented for the use of these factors in dose calculations for symmetric ally collimated square, rectangular and arbitrarily shaped fields, at an arbitrary SSD. These include blocked and wedged fields. A procedure to use Sc and Sp data in the calculation of monitor units is presented. Relations are given to calculate the collimator and phantom scatter data for the reference situation from already available data, measured at a non­ reference depth and at a non-reference SSD. The influence of asymmetric set-up of the collimating jaws or multi-leaf collimators on the scatter correction factors is, however, not yet considered. Scp, Sc and Sp data sets are presented in this report for different types of treatment machines and for a wide range of photon beams, with beam qualities ranging from 6°Co to 25 MV. Sp is shown to be a smooth f unction of the beam quality if the same reference depth of 10 cm and an SSD of 100 cm is chosen for all beam qualities. However, Sc is shown to depend on the design of the head of the linear accelerator