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Purpose: Whilst computed tomography (CT) imaging has been a vital component of injury management, its increasing use has raised concern regarding ionising radiation exposure. This study aims to identify latent classes (underlying patterns) of CT use over a 3-year period following the incidence of injury and factors predicting the observed patterns., Method: A retrospective observational cohort study was conducted in 21,544 individuals aged 18 + years presenting to emergency departments (ED) of four tertiary public hospitals with new injury in Western Australia. Mixture modelling approach was used to identify latent classes of CT use over a 3-year period post injury., Results: Amongst injured people with at least one CT scan, three latent classes of CT use were identified including a: temporarily high CT use (46.4%); consistently high CT use (2.6%); and low CT use class (51.1%). Being 65 + years or older, having 3 + comorbidities, history with 3 + hospitalisations and history of CT use before injury were associated with consistently high use of CT. Injury to the head, neck, thorax or abdomen, being admitted to hospital after the injury and arriving to ED by ambulance were predictors for the temporarily high use class. Living in areas of higher socio-economic disadvantage was a unique factor associated with the low CT use class., Conclusions: Instead of assuming a single pattern of CT use for all patients with injury, the advanced latent class modelling approach has provided more nuanced understanding of the underlying patterns of CT use that may be useful for developing targeted interventions., (© 2023. The Author(s).)

Objective: High use of CT scanning has raised concern due to the potential ionising radiation exposure. This study examined trends of CT during admission to tertiary hospitals and its associations with length of stay (LOS), readmission and mortality., Design: Retrospective observational study from 2003 to 2015., Setting: West Australian linked administrative records at individual level., Participants: 2 375 787 episodes of tertiary hospital admission in adults aged 18+ years., Main Outcome Measures: LOS, 30-day readmissions and mortality stratified by CT use status (any, multiple (CTs to multiple areas during episode), and repeat (repeated CT to the same area))., Methods: Multivariable regression models were used to calculate adjusted rate of CT use status. The significance of changes since 2003 in the outcomes (LOS, 30-day readmission and mortality) was compared among patients with specific CT imaging status relative to those without., Results: Between 2003 and 2015, while the rate of CT increased 3.4% annually, the rate of repeat CTs significantly decreased -1.8% annually and multiple CT showed no change. Compared with 2003 while LOS had a greater decrease in those with any CT, 30-day readmissions had a greater increase among those with any CT, while the probability of mortality remained unchanged between the any CT/no CT groups. A similar result was observed in patients with multiple and repeat CT scanning, except for a significant increase in mortality in the recent years in the repeat CT group., Conclusion: The observed pattern of increase in CT utilisation is likely to be activity-based funding policy-driven based on the discordance between LOS and readmissions. Meanwhile, the repeat CT reduction aligns with a more selective strategy of use based on clinical severity. Future research should incorporate in-hospital and out-of-hospital CT to better understand overall CT trends and potential shifts between settings over time., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: The professional service review (PSR) is an Australian Government agency aiming to reduce inappropriate practices funded via Medicare, Australia's public insurer. Our objective was to examine changes in CT following the 2008-2009 PSR annual report, which noted excessive CT use., Design: Interrupted time series analysis examined trends in CT use following the 2008-2009 PSR report, estimating both change in the immediate rate of CT and the slope of the trend in usage postintervention., Setting: Medicare-funded imaging (most out-of-hospital imaging) in Australia., Participants: Patients receiving Medicare-funded CT and other imaging., Intervention: The 2008-2009 PSR report highlighted concerns regarding excessive CT use. Two providers were financially penalised for CT overuse with these cases detailed in the PSR report and highlighted in an associated Report to the Professions, distributed to 50 000 providers. Media articles on radiation risks followed., Outcomes: Quarterly rates of out-of-hospital CT, MRI (as a comparator), and all other Medicare-funded diagnostic imaging examinations 2001-2019., Results: CT scanning increased from 4663.5 per 100 000 person-years in 2001 to 14 506 in 2019 (211% increase), with substantial variation by type and anatomical region. The 2008-2009 PSR report was followed by an immediate reduction in CT scanning of 237.7 CTs per 100 000 people per quarter (95% CI -333.4 to -141.9) though growth in use soon continued at the preintervention rate. The degree of change in utilisation following the report differed between states/territories and by scan type, both in terms of the immediate change and the slope. For other diagnostic imaging modalities, there was an increase in the slope, while for MRI there was no change in either parameter., Conclusion: Actions consisting of financial disincentives for service overtesting and provider/public education components may limit excessive use of diagnostic imaging in fee-for-service systems, however, effects observed here were only short lived., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objectives: While CT scanning plays a significant role in healthcare, its increasing use has raised concerns about inappropriate use. This study investigated factors driving the changing use of CT among people admitted to tertiary hospitals in Western Australia (WA)., Design and Setting: A repeated cross-sectional study of CT use in WA in 2003-2005 and 2013-2015 using linked administrative heath data at the individual patient level., Participants: A total of 2 375 787 tertiary hospital admissions of people aged 18 years or older., Main Outcome Measure: Rate of CT scanning per 1000 hospital admissions., Methods: A multivariable decomposition model was used to quantify the contribution of changes in patient characteristics and changes in the probability of having a CT over the study period., Results: The rate of CT scanning increased by 112 CT scans per 1000 admissions over the study period. Changes in the distribution of the observed patient characteristics were accounted for 62.7% of the growth in CT use. However, among unplanned admissions, changes in the distribution of patient characteristics only explained 17% of the growth in CT use, the remainder being explained by changes in the probability of having a CT scan. While the relative probability of having a CT scan generally increased over time across most observed characteristics, it reduced in young adults (-2.8%), people living in the rural/remote areas (-0.8%) and people transferred from secondary hospitals (-0.8%)., Conclusions: Our study highlights potential improvements in practice towards reducing medical radiation exposure in certain high risk population. Since changes in the relative probability of having a CT scan (representing changes in scope) rather than changes in the distribution of the patient characteristics (representing changes in need) explained a major proportion of the growth in CT use, this warrants more in-depth investigations in clinical practices to better inform health policies promoting appropriate use of diagnostic imaging tests., Competing Interests: Competing interests: The authors have no competing interest to declare. The institutions of RM, NH, DY, MB and DM received grant funding from the National Medical Research Council of Australia for investigator-initiated research. The funding agreement ensured author independence in designing the study, interpreting the data, writing and publishing the report., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: The overuse of diagnostic imaging for low back pain (LBP) in Australia results in unnecessary cost to the health system and, for patients, avoidable exposure to radiation. The 2013 NPS MedicineWise LBP program aimed to reduce unnecessary diagnostic imaging for non-specific acute LBP in the Australian primary care setting. The LBP program delivered referral pattern feedback, a decision support tool and patient information to 19,997 (60%) of registered Australian general practitioners (GPs). This study describes the findings from evaluation of the effectiveness of the 2013 LBP program at reducing X-ray and computed tomography (CT) scans of the lower back, and the financial costs and benefits of the program to the government funder., Methods: The effectiveness of the 2013 LBP program was evaluated using population-based time-series analysis of administrative claims data of Medicare Benefits Schedule (MBS) funded X-ray and CT scan services of the lower back. The CT scan referral trend of non-GP health professionals was used as an observational control group in a Bayesian structural time-series model. A retrospective cost-benefit analysis and cost-effectiveness analysis was conducted using program costs from organisational records and reimbursement data from the MBS., Results: The 2013 NPS MedicineWise LBP program was associated with a statistically significant 10.85% relative reduction in the volume of CT scans of the lumbosacral region, equating to a cost reduction to the MBS of AUD$11,600,898. The best available estimate of program costs was AUD$141,154. Every dollar of funding spent on the 2013 LBP program saved AUD$82 of funding to the MBS for CT scan reimbursements. Therefore, from the perspective of the Australian Government Department of Health, the 2013 LBP program was cost saving. The program cost AUD$2.82 per CT scan averted in comparison to the scenario of no program. No association between the 2013 NPS MedicineWise LBP program and the volume of X-ray items on the MBS was observed., Conclusions: The 2013 NPS MedicineWise LBP program reduced CT scan referral by GPs, in line with the program's messages and clinical guidelines. Reducing this low-value care produced savings to the health system that exceeded the costs of program implementation.

Objective: Organ radiation dose from a CT scan, calculated by CT dosimetry software, can be combined with cancer risk data to estimate cancer incidence resulting from CT exposure. We aim to determine to what extent the use of improved anatomical representation of the adult human body "phantom" in CT dosimetry software impacts estimates of radiation dose and cancer incidence, to inform comparison of past and future research., Methods: We collected 20 adult cases for each of three CT protocols (abdomen/pelvis, chest and head) from each of five public hospitals (random sample) (January-April inclusive 2010) and three private clinics (self-report). Organ equivalent and effective dose were calculated using both ImPACT (mathematical phantom) and NCICT (voxelised phantom) software. Bland-Altman plots demonstrate agreement and Passing-Bablok regression reports systematic, proportional or random differences between results. We modelled the estimated lifetime attributable risk of cancer from a single exposure for each protocol, using age-sex specific risk-coefficients from the Biologic Effects of Ionizing Radiation VII report., Results: For the majority of organs used in epidemiological studies of cancer incidence, the NCICT software (voxelised) provided higher dose estimates. Across the lifespan NCICT resulted in cancer estimates 2.9%-6.6% and 14.8%-16.3% higher in males and females (abdomen/pelvis) and 7.6%-19.7% and 12.9%-26.5% higher in males and females respectively (chest protocol). For the head protocol overall cancer estimates were lower for NCICT, but with greatest disparity, >30% at times., Conclusion: When the results of previous studies estimating CT dose and cancer incidence are compared to more recent, or future, studies the dosimetry software must be considered. Any change in radiation dose or cancer risk may be attributable to the software and phantom used, rather than-or in addition to-changes in scanning practice. Studies using dosimetry software to estimate radiation dose should describe software comprehensively to facilitate comparison with past and future research., Competing Interests: The authors have declared that no competing interests exist.

Background: Publicly funded computed tomography (CT) procedure descriptions in Australia often specify the body site, rather than indication for use. This study aimed to evaluate the relative contribution of demographic versus non-demographic factors in driving the increase in CT services in Australia., Methods: A decomposition analysis was conducted to assess the proportion of additional CT attributable to changing population structure, CT use on a per capita basis (CPC, a proxy for change in practice) and/or cost of CT. Aggregated Medicare usage and billing data were obtained for selected years between 1993/4 and 2012/3., Results: The number of billed CT scans rose from 33 per annum per 1000 of population in 1993/94 (total 572,925) to 112 per 1000 by 2012/13 (total 2,540,546). The respective cost to Medicare rose from $145.7 million to $790.7 million. Change in CPC was the most important factor accounting for changes in CT services (88%) and cost (65%) over the study period., Conclusions: While this study cannot conclude if the increase is appropriate, it does represent a shift in how CT is used, relative to when many CT services were listed for public funding. This 'scope shift' poses questions as to need for and frequency of retrospective/ongoing review of publicly funded services, as medical advances and other demand- or supply-side factors change the way health services are used., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Purpose: To evaluate the effect of introduction of iterative reconstruction as a mandated software upgrade on radiation dosimetry in routine clinical practice over a range of computed tomography examinations., Methods: Random samples of scanning data were extracted from a centralised Picture Archiving Communication System pertaining to 10 commonly performed computed tomography examination types undertaken at two hospitals in Western Australia, before and after the introduction of iterative reconstruction. Changes in the mean dose length product and effective dose were evaluated along with estimations of associated changes to annual cancer incidence., Results: We observed statistically significant reductions in the effective radiation dose for head computed tomography (22-27%) consistent with those reported in the literature. In contrast the reductions observed for non-contrast chest (37-47%); chest pulmonary embolism study (28%), chest/abdominal/pelvic study (16%) and thoracic spine (39%) computed tomography. Statistically significant reductions in radiation dose were not identified in angiographic computed tomography. Dose reductions translated to substantial lowering of the lifetime attributable risk, especially for younger females, and estimated numbers of incident cancers., Conclusion: Reduction of CT dose is a priority Iterative reconstruction algorithms have the potential to significantly assist with dose reduction across a range of protocols. However, this reduction in dose is achieved via reductions in image noise. Fully realising the potential dose reduction of iterative reconstruction requires the adjustment of image factors and forgoing the noise reduction potential of the iterative algorithm. Our study has demonstrated a reduction in radiation dose for some scanning protocols, but not to the extent experimental studies had previously shown or in all protocols expected, raising questions about the extent to which iterative reconstruction achieves dose reduction in real world clinical practice.

Background: Computed tomography (CT) scanning is a relatively high radiation dose diagnostic imaging modality with increasing concerns about radiation exposure burden at the population level in scientific literature. This study examined the epidemiology of adult CT utilisation in Western Australia (WA) in both the public hospital and private practice settings, and the policy implications., Methods: Retrospective cohort design using aggregate adult CT data from WA public hospitals and Medical Benefits Schedule (MBS) (mid-2006 to mid-2012). CT scanning trends by sex, age, provider setting and anatomical areas were explored using crude CT scanning rates, age-standardised CT scanning rates and Poisson regression modelling., Results: From mid-2006 to mid-2012 the WA adult CT scanning rate was 129 scans per 1,000 person-years (PY). Females were consistently scanned at a higher rate than males. Patients over 65 years presented the highest scanning rates (over 300 scans per 1,000 PY). Private practice accounted for 73% of adult CT scans, comprising the majority in every anatomical area. In the private setting females predominately held higher age-standardised CT scanning rates than males. This trend reversed in the public hospital setting. Patients over 85 years in the public hospital setting were the most likely age group CT scanned in nine of ten anatomical areas. Patients in the private practice setting aged 85+ years were relatively less prominent across every anatomical area, and the least likely age group scanned in facial bones and multiple areas CT scans., Conclusion: In comparison to the public hospital setting, the MBS subsidised private sector tended to service females and relatively younger patients with a more diverse range of anatomical areas, constituting the majority of CT scans performed in WA. Patient risk and subsequent burden is greater for females, lower ages and some anatomical areas. In the context of a national health system, Australia has various avenues to monitor radiation exposure levels, improve physician training and modify funding mechanisms to ensure individual and population medical radiation exposure is as low as reasonably achievable.

Objectives: To explore the interaction of computed tomography (CT) use, dose and radiation risk of Australian Medicare-funded CT scanning and the impact on cancer incidence and mortality., Methods: This retrospective cohort study used records of Medicare subsidised CT scans in Australia (2006/07 to 2011/12) and Australian CT dosimetry. The annual number, rate and adjusted likelihood of CT were determined for gender, age and examination type. Incident cancer and cancer-related mortality attributable to CT in Australia were estimated using lifetime attributable risk coefficients, dosimetry and scan numbers., Results: The number of CT scans increased by 36% from 2006/07 to 2011/12. Only patients aged 0-4 years did not present an increase in CT scanning rates. Females were 11% more likely to be scanned than males. Head, abdomen/pelvis and spine CT scans were the most likely areas scanned. Females were attributed 61% of both incident cancers and cancer-related mortality from 55% of scans performed. Patients aged 15-44 years were attributed 37% of incident cancers and 30% of cancer-related mortality from 26% of CT scans., Conclusions: CT in Australia is increasing, including in groups at higher risk from ionising radiation. This presents a complex set of risk/benefit considerations for clinicians and policy makers., (© 2014 Public Health Association of Australia.)

Objective: Choosing to undertake a CT scan relies on balancing risk versus benefit, however risks associated with CT scanning have generally been limited to broad anatomical locations, which do not provided adequate information to evaluate risk against benefit. Our study aimed to determine differences in radiation dose and risk estimates associated with modern CT scanning examinations when computed for clinical protocols compared with those using anatomical area., Methods: Technical data were extracted from a tertiary hospital Picture Archiving Communication System for random samples of 20-40 CT examinations per adult clinical CT protocol. Organ and whole body radiation dose were calculated using ImPACT Monte Carlo simulation software and cancer incidence and mortality estimated using BEIR VII age and gender specific lifetime attributable risk weights., Results: Thirty four unique CT protocols were identified by our study. When grouped according to anatomic area the radiation dose varied substantially, particularly for abdominal protocols. The total estimated number of incident cancers and cancer related deaths using the mean dose of anatomical area were 86 and 69 respectively. Using more specific protocol doses the estimates rose to 214 and 138 incident cancers and cancer related deaths, at least doubling the burden estimated., Conclusions: Modern CT scanning produces a greater diversity of effective doses than much of the literature describes; where a lack of focus on actual scanning protocols has produced estimates that do not reflect the range and complexity of modern CT practice. To allow clinicians, patients and policy makers to make informed risk versus benefit decisions the individual and population level risks associated with modern CT practices are essential.

Objective: Concerns about the radiation dose associated with CT scanning have led to a call for establishment of diagnostic reference levels. Self-complete surveys have been used extensively to gather this information, however, departmental Radiological Information System's/Picture Archive Communication Systems (RIS/PACS) also hold this information. We compared dosimetry derived from survey with that using RIS/PACSs., Methods: Technical data were collected from a large metropolitan tertiary hospital in WA using both data collection methods for a range of adult CT scanning examinations. Radiation dose was calculated from both datasets and the results evaluated for several indexes of inter-rater agreement., Results: Radiation dose calculated using self-report survey data differed both systematically and proportionally from that calculated using RIS/PACS data. Differences were not consistent across CT examination type and thus not amenable to simple correction. The disparity was greater and more variable for organ dose than effective dose due to reliance of survey data on "generic" anatomical start and stop limits compared with actual data available on RIS/PACS., Conclusions: The bias observed in our study indicates that care should be taken when interpreting the results of studies measuring radiation dose using self-complete surveys. The availability of electronic databases that include information required for the evaluation and monitoring of CT radiation dose provides the opportunity to capture better quality data in a cost-effective manner. We recommend that national and local databases are established that routinely capture these data so as to facilitate the development and monitoring of radiation dose associated with CT scanning., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Technical data on local CT practice in Western Australia were collected for five major CT providers using a self-completed questionnaire. The CTDIvol DLP and effective dose for each protocol were obtained and providers were ranked according to radiation burden for each clinical scenario. The mean, median, 75th percentile and standard deviation were calculated for both effective dose and DLP for each scenario and these values were compared with published data. CT utilisation data were used to estimate the attributable radiation dose to the WA population and the potential change in population annual effective dose according to the protocol used was estimated. We found that wide variations in technique and radiation dose exist across providers for similar examinations, producing a higher radiation burden than reported internationally. As expected, the CT protocol used dramatically affects the radiation dose received, and this has a significant effect on annual population dose. This study highlights the need for recognition and understanding of both the degree of variation in radiation dose across providers and the relatively high radiation burden afforded by protocols in use in Western Australia so that necessary dialogue can be launched for practitioner consensus on appropriate diagnostic reference levels in CT scanning.