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Objective: To present the results following a UK national patient dose audit of paediatric CT examinations, to propose updated UK national diagnostic reference levels (DRLs) and to analyse current practice to see if any recommendations can be made to assist with optimisation. Methods: A UK national dose audit was undertaken in 2019 focussing on paediatric CT examinations of the head, chest, abdomen/pelvis and cervical spine using the methods proposed by the International Commission on Radiological Protection. The audit pro-forma contained mandatory fields, of which the post-examination dosimetry (volume CT dose index and dose–length product) and the patient weight (for body examinations) were the most important. Results: Analysis of the data submitted indicates that it is appropriate to propose national DRLs for CT head examinations in the 0-p). Conclusion: Updated UK national DRLs are proposed for paediatric CT examinations of the head and chest. Advances in knowledge: A national patient dose audit of paediatric CT examinations has led to the proposal of updated national DRLs.

Introduction:Cone beam computed tomography (CBCT) is increasingly seen in UK dental practices, but there is no published information regarding how it is used. The aim of the study was to obtain such information using a survey. Materials and Methods:A survey on aspects of justification, optimisation and training was distributed to all dental practices having CBCT equipment and a contract with Dental X-ray Protection Services (DXPS). Results:Seventy-one completed surveys were received (49% response rate). A wide range of CBCT equipment was in use. The number of scans reported as being carried out was typically low. One third of respondents had acquired their CBCT machine within the last year. The clinical use was overwhelmingly in adult patients and related to implant dentistry. Small or medium field of view scans were most commonly used. Only 19.7% of respondents could provide detailed exposure factors. Patient protective shielding for patients was almost never used. The dentist always or mainly performed the CBCT reporting in 88.7% of practices. Conclusions:The survey provided no evidence of excessive use of CBCT in UK dental practices. The typical reported use was of small field of view scans for implant dentistry. Only 8.4% of practices performed examinations on children and young people. Some concerns were raised regarding respondents’ knowledge about exposure factors and the clinical evaluation of images.

The aim of this study was to quantify the levels of transmitted radiation arising from the use of intra-oral dental x-ray equipment and scattered radiation arising from the use of both intra-oral and panoramic x-ray equipment. Levels of scattered radiation were measured at 1 m from a phantom, using an ion chamber with a volume of 1800 cm3. Transmitted radiation was measured using both (i) a phantom and dose-area product (DAP) meter and (ii) a patient and a 1800 cm3 ion chamber. For intra-oral radiography the patient study gave a maximum transmission of 1.80% (range 0.04-1.80%, mean 0.26%) and the phantom study gave a maximum transmission of 6% (range 2-6%, mean 5%). The maximum scattered radiation, per unit DAP, was 5.5 nGy (mGy cm2)-1 at 70 kVp and a distance of 1 m. For panoramic radiography the maximum scattered radiation was 9.3 nGy (mGy cm2)-1 at 80 kVp and a distance of 1 m. Dose values are presented to enable the calculation of adequate protective measures for dental radiography rooms. Previous studies have used a phantom and measured radiation doses at 1 m from the phantom to determine the radiation dose transmitted through a patient, whereas this study uses both patient and phantom measurements together with a large-area dosemeter, positioned to capture the entire x-ray beam, to ensure that more realistic dose measurements can be made.

Purpose The protocol for quality control of CBCT devices was produced as consensus among active MPEs of EFOMP, ESTRO and IAEA. It is available on-line since September 2017. In the beginning of 2018 we published an update including an appendix on patient dosimetry by EURADOS, comments by the German institute of standards (DIN) and remarks by users from countries that were not involved in the first edition, such as Austria, Costa Rica and Australia. This contribution gives a general overview of the guideline including insights about this recent update. Methods The guideline focuses on the measurement of objective image quality parameters and radiation output from any kind of CBCT device, including applications in dental radiology, C-arms and guidance systems in radiotherapy. Indications to use commercial or non-commercial phantoms and software are given, as well as to use ionization chambers or solid state dosemeters. The new EURADOS appendix includes an extensive review of patient dose data from recent research papers, organized by application and dose indicators: CTDI, DAP, effective dose, entrance surface dose, CTDIw, absorbed dose, D1-D2 and air kerma. The DIN has reviewed the details of the standards 6868–161 and 6868–15 for acceptance and constancy tests in dental CBCT. Individual comments have helped to clarify the measurements of radiation output and the methods to measure the modulation transfer function. Some colleagues have stressed the informative value of the appendices. Results The comments received were reviewed by the authors of the corresponding sections and discussed by the group in virtual meetings before being published as an update. The mentioned additions are meant to keep the document alive. They respond to questions raised by physicists that are starting to use the protocol inside and outside Europe. Conclusions The first presentation in the ECMP in Athens was followed by international presentations at ESTRO, ECR, IOMP and IRPA and national presentations in Italy, Spain, UK, Germany and other countries. Thanks to these voluntary efforts, physicists around the world are using and improving the document together. We also welcome your participation in this session and your feedback.

This is the second paper arising from a project concerning the application of Monte Carlo simulations to provide scanner-specific organ dose coefficients for modern CT scanners. The present focus is centred on the bone dosimetry models that have been developed. Simulations have been performed in photon only transport mode, with the assumption of electron equilibrium. This approximation breaks down for doses to active marrow and endosteum since the target cells are localised within tens of micrometre from bone tissue and dose enhancement functions are necessary to correct for the additional dose from photoelectric electrons created in adjacent material. The dose enhancement models used previously in publications NRPB-SR250 (Jones and Shrimpton 1993 Software Report NRPB-SR250, National Radiological Protection Board, Chilton, UK) and ORNL-TM8381 (Cristy and Eckerman 1987 Technical Report Oak Ridge National Laboratory, Oak Ridge, TN) have been implemented and compared with the contemporary approaches of Johnson et al (2011 Phys. Med. Biol. 56 2347-65) and ICRP Publication 116 (ICRP 2010 Ann. ICRP 40 1-257) that are being adopted in the present project. In addition, the calculation of dose to endosteum in the medullary cavity is reviewed and updated using electron mode simulations. For the purposes of quality assurance and comparison, the various dose enhancement functions have been applied in relation to the NRPB18+DJ and HPA18+ stylised hermaphrodite phantoms and also the adult male and female voxel phantoms recommended in ICRP Publication 110 (ICRP 2009 Ann. ICRP 39 1-165), for exposure from three CT scanners modelled previously. Contemporary results for standard examinations on the head and trunk calculated for these latter phantoms demonstrate moderate increases (modal value +18%) in active marrow dose coefficients relative to values derived from data published in NRPB-SR250. A similar analysis in relation to endosteum dose coefficients shows larger reductions (modal value -46%), owing at least in part to changes in assumed location of the target cells. Even larger changes are apparent for both of these dose coefficients in relation to examination of the upper legs (-39% and -94%, respectively). However, resultant changes in any values of effective dose will be less owing to the low weighting factors applied for these tissues.

Objective: To review doses to patients undergoing cervical spine CT examinations in the UK. Methods: A data collection form was developed and distributed to medical physicists and radiographers via e-mail distribution lists. The form requested details of CT scanners, exposure protocols and patient dose index information. Results: Data were received for 73 scanners. It was seen that 97% of scanners used automatic exposure control, and 60% of scanners used an iterative reconstruction technique for cervical spine examinations. The majority of scans were taken at 120 kV. The average patient dose indicators in terms of CT dose index (CTDIvol) ranged from 3.5 to 39.7 mGy (mean value 16.7 mGy), and for the DLP, ranged from 87 to 1030 mGy cm (mean value 379 mGy cm) as quoted for the standard 32 cm phantom. Conclusion: The rounded third quartile value of the mean dose distributions from this study were a CT dose index (CTDIvol) of 20 mGy and a dose–length product of 440 mGy cm as quoted for a 32 cm body phantom. These are significantly higher than those in the 2011 Public Health England CT dose survey when adjusted for phantom size. It is suggested that the existing national diagnostic reference levels for cervical spine CT should be amended, both with the new values and also to quote according to the 32 cm phantom. Advances in knowledge: Proposed new national diagnostic reference levels are presented for cervical spine CT examinations.

Introduction Current guidelines for quality control of CBCT devices consider the available applications (dental, radiotherapy, interventional radiology and guided surgery) as different entities. However, the data acquisition and reconstruction methods are similar. Henceforth, the evaluation parameters for image quality and dose can be unified. Purpose The purpose of this guideline (under discussion since January 2014 within an EFOMP working group) is to present an objective, practical and unifying procedure for quality control of all imaging CBCT applications Materials and methods The parameters used for image quality assessment are uniformity, accuracy of density values (or Hounsfield units where appropriate), geometrical evaluation, noise, low contrast resolution (including contrast to noise ratio) and high contrast resolution. Results Detailed procedures using free software and commercially available test phantoms are described. The dosimetric quantities under consideration are CTDI, kerma area product and detector incident air kerma. Recommended action levels and test frequency are indicated together with references wherever possible. Conclusion This guideline includes the minimum tests that should be performed to ensure reliable, safe and consistent performance of CBCT devices. This minimum has been sought to guarantee compatibility with all manufacturers and existing European documents (DIN 6868161, HPACRCE010 and RP 172 for dental applications). Disclosure Nothing to disclose.

Diagnostic reference levels (DRLs) are an important tool in the optimisation of clinical radiography. Although national DRLs are provided for many diagnostic procedures including dental intra-oral radiography, there are currently no national DRLs set for cephalometric radiography. In the absence of formal national DRLs, the Health Protection Agency (HPA) has previously published National Reference Doses (NRDs) covering a wide range of diagnostic X-ray examinations. The aim of this study was to determine provisional NRDs for cephalometric radiography.Measurements made by the Dental X-ray Protection Service (DXPS) of the HPA, as part of the cephalometric X-ray equipment testing service provided to dentists and dental trade companies throughout the UK, were used to derive provisional NRDs.Dose-area product measurements were made on 42 X-ray sets. Third quartile dose-area product values for adult and child lateral cephalometric radiography were found to be 41 mGy cm² and 25 mGy cm², respectively, with individual measurements ranging from 3 mGy cm² to 108 mGy cm².This report proposes provisional NRDs of 40 mGy cm² and 25 mGy cm² for adult and child lateral cephalometric radiographs, respectively; these doses could be considered by employers when establishing their local DRLs.

To address whether St John's wort is useful for the treatment of depression we attempted to retrieve all English-language articles with data on the efficacy, safety, and availability of St John's wort. Randomized, controlled, double-blind trials were selected and assessed for methodological quality using a standardized checklist, and data on pharmacology, cost, regulation, and safety were extracted. Eight studies were identified, found to be of generally good methodological quality, and determined to provide a modest amount of data to suggest that St John's wort is more effective than placebo in the treatment of mild to moderate depression. The absolute increased response rate with the use of St John's wort ranged from 23% to 55% higher than with placebo, but ranged from 6% to 18% lower compared with tricyclic antidepressants. More data are required to assess both its use in severe depression and its efficacy compared with other antidepressants. Rates of side effects were low. As a dietary supplement, St John's wort is currently largely unregulated, but the Food and Drug Administration is reviewing plans to tighten its regulatory oversight.

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