Fourth review of the UK national patient dose database

Panoramic dental X-ray exposure leads to oxidative stress, inflammation and apoptosis-mediated developmental defects in zebrafish embryos

Panoramic x-ray units are widely used in dental radiodiagnostics. Patients are exposed to relatively low radiation doses with panoramic imaging, but considering lifetime frequency of exposure, even a small risk can have serious health consequences. Our aim was to assess the effects of panoramic x-rays at two different exposure times on developing zebrafish embryos, focusing on oxidative stress, inflammation, apoptotic pathways, and development. Zebrafish embryos were divided into three groups: control, standard panoramic (SPE, 5.5 s exposure time) and pedodontic panoramic x-ray group (PPE, 4.8 s exposure time). Optically stimulated luminescence dosimeters were used to measure absorbed doses. Mean radiation doses for SPE and PPE were 7.83 mSv and 5.83 mSv respectively. At the end of 96 h post-fertilization, lipid peroxidation (LPO), nitric oxide (NO), reduced glutathione (GSH), glutathione S-transferase and superoxide dismutase were measured in the embryos. Expressions of genes related with inflammation (tnfα, il6, ill15, il21), immunoregulation (ifng) and apoptosis (p53, bax, casp2, casp3, casp8) were determined by RT-PCR. Even at reduced doses at high-speed mode, developmental toxicity was observed in both groups as evidenced by decreased pigmentation, yolk sac oedema, and spinal curvature. While deterioration of oxidant-antioxidant balance, suppression of immune response, induction of inflammation and apoptosis were observed through increased LPO, NO, decreased GSH, ifng, and increased expressions of genes related with inflammation and apoptosis, these effects were more pronounced in the SPE group. These results demonstrate the influence of exposure time and indicate the need for further consideration of optimal panoramic modes from a radiation-induced damage perspective.

Radiation risk issues in recurrent imaging

Millions of patients benefit from medical imaging every single day. However, we have entered an unprecedented era in imaging practices wherein 1 out of 125 patients can be exposed to effective dose >50 mSv from a single CT exam and 3 out of 10,000 patients undergoing CT exams could potentially receive cumulative effective doses > 100 mSv in a single day. Recurrent imaging with CT, fluoroscopically guided interventions, and hybrid imaging modalities such as positron emission tomography/computed tomography (PET/CT) is more prevalent today than ever before. Presently, we do not know the cumulative doses that patients may be receiving across all imaging modalities combined. Furthermore, patients with diseases with longer life expectancies are being exposed to high doses of radiation enabling radiation effects to manifest over a longer time period. The emphasis in the past on improving justification of imaging and optimization of technique and practice has proved useful. While that must continue, the current situation requires imaging device manufacturers to urgently develop imaging technologies that are safer for patients as high doses have been observed in patients where imaging has been justified through clinical decision-support and optimized by keeping doses below the national benchmark doses. There is a need to have a critical look at the fundamental principles of radiation protection as cumulative doses are likely to increase in the coming years.

Patient radiation dose in percutaneous biliary interventions: recommendations for DRLs on the basis of a multicentre study

OBJECTIVE

Percutaneous biliary interventions (PBIs) can be associated with a high patient radiation dose, which can be reduced when national diagnostic reference levels (DRLs) are kept in mind. The aim of this multicentre study was to investigate patient radiation exposure in different percutaneous biliary interventions, in order to recommend national DRLs.

METHODS

A questionnaire asking for the dose area product (DAP) and the fluoroscopy time (FT) in different PBIs with ultrasound- or fluoroscopy-guided bile duct punctures was sent to 200 advanced care hospitals. Recommended national DRLs are set at the 75th percentile of all DAPs.

RESULTS

Twenty-three facilities (9 interventional radiology depts. and 14 gastroenterology depts.) returned the questionnaire (12%). Five hundred sixty-five PBIs with 19 different interventions were included in the analysis. DAPs (range 4-21,510 cGy·cm2) and FTs (range 0.07-180.33 min) varied substantially depending on the centre and type of PBI. The DAPs of initial PBIs were significantly (p < 0.0001) higher (median 2162 cGy·cm2) than those of follow-up PBIs (median 464 cGy·cm2). There was no significant difference between initial PBIs with ultrasound-guided bile duct puncture (2162 cGy·cm2) and initial PBIs with fluoroscopy-guided bile duct puncture (2132 cGy·cm2) (p = 0.85). FT varied substantially (0.07-180.33 min).

CONCLUSIONS

DAPs and FTs in percutaneous biliary interventions showed substantial variations depending on the centre and the type of PBI. PBI with US-guided bile duct puncture did not reduce DAP, when compared to PBI with fluoroscopy-guided bile duct puncture. National DRLs of 4300 cGy·cm2 for initial PBIs and 1400 cGy·cm2 for follow-up PBIs are recommended.

KEY POINTS

• DAPs and FTs in percutaneous biliary interventions showed substantial variations depending on the centre and the type of PBI. • PBI with US-guided bile duct puncture did not reduce DAP when compared to PBI with fluoroscopy-guided bile duct puncture. • DRLs of 4300 cGy·cm2for initial PBIs (establishing a transhepatic tract) and 1400 cGy·cm2for follow-up PBIs (transhepatic tract already established) are recommended.

Establishment of national diagnostic reference levels (DRLs) for radiotherapy localisation computer tomography of the head and neck

AIM

The aim of this research is to establish if variation exists in the dose delivered for head and neck (HN) localisation computed tomography (CT) imaging in radiation therapy (RT); to propose a national diagnostic reference levels (DRLs) for this procedure and to make a comparison between the national DRL and a DRL of a European sample.

BACKGROUND

CT has become an indispensable tool in radiotherapy (RT) treatment planning. It is a requirement of legislation in many countries that doses of ionising radiation for medical exposures be kept 'As Low As Reasonably Achievable'. There are currently no dose guidelines for RT localisation CT of the HN.

MATERIALS AND METHODS

All RT departments in Ireland and a sample of European departments were surveyed. Dose data on CT dose length product (DLP); dose index volume (CTDIvol); current time product; tube voltage and scan length was acquired for ten average-sized HN patients from each department. DRLs were proposed for DLP and CTDIvol using the rounded 75th percentile of the distribution of the means.

RESULTS

42% of Irish departments and one European department completed the survey. Significant variation was found in the mean DLP, CTDIvol and scan lengths across the Irish departments. The proposed Irish DRL is 882 mGy cm and 21 mGy and the European department DRL is 816 mGy cm and 21 mGy, for DLP and CTDIvol, respectively.

CONCLUSIONS

Variation exists in doses used for HN RT localisation CT. DRLs have been proposed for comparison purposes with the aim of dose optimisation.

Patient dose measurement in common medical X-ray examinations and propose the first local dose reference levels to diagnostic radiology in Iran

Introduction: The main purpose of this study was to investigate patient dose in pelvic and abdomen x-ray examinations. This work also provided the LDRLs (local diagnostic reference levels) in Khuzestan region, southwest of Iran to help establish the NDRLs (national diagnostic reference levels).

Methods: Patient doses were assessed from patient’s anatomical data and exposure parameters based on the IAEA indirect dosimetry method. With regard to this method, exposure parameters such as tube output, kVp, mAs, FFD and patient anatomical data were used for calculating ESD (entrance skin dose) of patients. This study was conducted on 250 standard patients (50% men and 50% women) at eight high-patient-load imaging centers.

Results: The results indicate that mean ESDs for the both pelvic and abdomen examinations were lower than the IAEA and EC reference levels, 2.3 and 3.7 mGy, respectively. Mean applied kVps were 67 and 70 and mean FFDs were 103 and 109, respectively. Tube loadings obtained in this study for pelvic examination were lower than all the corresponding values in the reviewed literature. Likewise, the average annual patient load across all hospitals were more than 37000 patients, i.e. more than 100 patients a day.

Conclusions: The authors recommend that DRLs (diagnostic reference levels) obtained in this region, which are the first available data, can be used as local DRLs for pelvic and abdomen procedures. This work also provides that on-the-job training programs for staffs and close cross collaboration between physicists and physicians should be strongly considered.

Diagnostic reference levels in low- and middle-income countries: early "ALARAm" bells?

Background In 1996 the International Commission on Radiological Protection (ICRP) introduced diagnostic reference levels (DRLs) as a quality assurance tool for radiation dose optimization. While many countries have published DRLs, available data are largely from high-income countries. There is arguably a greater need for DRLs in low- and middle-income-countries (LMICs), where imaging equipment may be older and trained imaging technicians are scarce. To date, there has been no critical analysis of the published work on DRLs in LMICs. Such work is important to evaluate data deficiencies and stimulate future quality assurance initiatives. Purpose To review the published work on DRLs in LMICs and to critically analyze the comprehensiveness of available data. Material and Methods Medline, Scopus, and Web of Science database searches were conducted for English-language articles published between 1996 and 2015 documenting DRLs for diagnostic imaging in LMICs. Retrieved articles were analyzed and classified by geographical region, country of origin, contributing author, year of publication, imaging modality, body part, and patient age. Results Fifty-three articles reported DRLs for 28 of 135 LMICs (21%), reflecting data from 26/104 (25%) middle-income countries and 2/31 (6%) low-income countries. General radiography (n = 26, 49%) and computerized tomography (n = 17, 32%) data were most commonly reported. Pediatric DRLs (n = 14, 26%) constituted approximately one-quarter of published work. Conclusion Published DRL data are deficient in the majority of LMICs, with the paucity most striking in low-income countries. DRL initiatives are required in LMICs to enhance dose optimization.

American College of Radiology Dose Index Registry: A User's Guide for Cardiothoracic Radiologists Part 1: Dose Index Registry (DIR)-What it Means and Does for CT?

Computed tomography (CT) is an indispensable part of diagnostic imaging and contributes significantly to patient care. With increasing use of CT, there have been growing concerns regarding risks from radiation exposure. This has prompted efforts to introduce measures to optimize the radiation dose used in CT imaging. The Dose Index Registry (DIR) was launched by the American College of Radiology (ACR) in 2011. It provides a national database of radiation dose indices for various CT examinations performed at participating institutions. It affords an opportunity for institutions to compare and tailor their CT protocols against existing national averages. In this article, we review the history, mechanism, and major elements of the DIR. We also briefly discuss similar radiation dose registries in other countries.

Dose surveys and DRLs: critical look and way forward

The main purpose of dose surveys has been to detect and bring down wide variation in radiation doses for any particular radiological examination and to avoid doses that are on higher side. Diagnostic reference levels (DRLs) have been used for over two decades as an aid in this objective. With very limited success that has been achieved through DRL, the author has recently described a new term 'acceptable quality dose' (AQD) that is aimed at optimisation within the DRL, is facility initiated and takes into account all three important parameters-image quality, dose and patient's body build. It is hoped that AQD will be found easy to establish, will be a useful tool to achieve optimisation in the facilities and will serve as the standard dose.

Radiation dose metrics in CT: assessing dose using the National Quality Forum CT patient safety measure

PURPOSE

The National Quality Forum (NQF) is a nonprofit consensus organization that recently endorsed a measure focused on CT radiation doses. To comply, facilities must summarize the doses from consecutive scans within age and anatomic area strata and report the data in the medical record. Our purpose was to assess the time needed to assemble the data and to demonstrate how review of such data permits a facility to understand doses.

METHODS AND MATERIALS

To assemble the data we used for analysis, we used the dose monitoring software eXposure to automatically export dose metrics from consecutive scans in 2010 and 2012. For a subset of 50 exams, we also collected dose metrics manually, copying data directly from the PACS into an excel spreadsheet.

RESULTS

Manual data collection for 50 scans required 2 hours and 15 minutes. eXposure compiled the data in under an hour. All dose metrics demonstrated a 30% to 50% reduction between 2010 and 2012. There was also a significant decline and a reduction in the variability of the doses over time.

CONCLUSION

The NQF measure facilitates an institution's capacity to assess the doses they are using for CT as part of routine practice. The necessary data can be collected within a reasonable amount of time either with automatic software or manually. The collection and review of these data will allow facilities to compare their radiation dose distributions with national distributions and allow assessment of temporal trends in the doses they are using.