Large variation in radiation dose for routine abdomen CT: reasons for excess and easy tips for reduction

OBJECTIVE

To characterize the use and impact of radiation dose reduction techniques in actual practice for routine abdomen CT.

METHODS

We retrospectively analyzed consecutive routine abdomen CT scans in adults from a large dose registry, contributed by 95 hospitals and imaging facilities. Grouping exams into deciles by, first, patient size, and second, size-adjusted dose length product (DLP), we summarized dose and technical parameters and estimated which parameters contributed most to between-protocols dose variation. Lastly, we modeled the total population dose if all protocols with mean size-adjusted DLP above 433 or 645 mGy-cm were reduced to these thresholds.

RESULTS

A total of 748,846 CTs were performed using 1033 unique protocols. When sorted by patient size, patients with larger abdominal diameters had increased dose and effective mAs (milliampere seconds), even after adjusting for patient size. When sorted by size-adjusted dose, patients in the highest versus the lowest decile in size-adjusted DLP received 6.4 times the average dose (1680 vs 265 mGy-cm) even though diameter was no different (312 vs 309 mm). Effective mAs was 2.1-fold higher, unadjusted CTDIvol 2.9-fold, and phase 2.5-fold for patients in the highest versus lowest size-adjusted DLP decile. There was virtually no change in kV (kilovolt). Automatic exposure control was widely used to modulate mAs, whereas kV modulation was rare. Phase was the strongest driver of between-protocols variation. Broad adoption of optimized protocols could result in total population dose reductions of 18.6-40%.

CONCLUSION

There are large variations in radiation doses for routine abdomen CT unrelated to patient size. Modification of kV and single-phase scanning could result in substantial dose reduction.

CLINICAL RELEVANCE

Radiation dose-optimization techniques for routine abdomen CT are routinely under-utilized leading to higher doses than needed. Greater modification of technical parameters and number of phases could result in substantial reduction in radiation exposure to patients.

KEY POINTS

• Based on an analysis of 748,846 routine abdomen CT scans in adults, radiation doses varied tremendously across patients of the same size and optimization techniques were routinely under-utilized. • The difference in observed dose was due to variation in technical parameters and phase count. Automatic exposure control was commonly used to modify effective mAs, whereas kV was rarely adjusted for patient size. Routine abdomen CT should be performed using a single phase, yet multi-phase was common. • kV modulation by patient size and restriction to a single phase for routine abdomen indications could result in substantial reduction in radiation doses using well-established dose optimization approaches.

Doctor as criminal: reporting of patient deaths to the police and criminal prosecution of healthcare providers in Japan

Background

In Japan, medical error leading to patient death is often handled through the criminal rather than civil justice system. However, the number of cases handled through the criminal system and how this has changed in recent years has not previously been described. Our aim was to determine the trend in reports of patient death to the police and the trend in the resulting prosecution of healthcare providers for medical error leading to patient death from 1998 to 2008.

Methods

We collected data regarding the number of police reports of patient death made by physicians, next-of-kin, and other sources between 1998 and 2008. We also collected data regarding the number of resulting criminal prosecutions of healthcare providers between 1998 and 2008. Reporting and prosecution trends were analyzed using annual linear regression models.

Results

Reports: The number physician reports of patient deaths to the police increased significantly during the study period (slope 18.68, R² = 0.78, P < 0.001) while reports made by next-of-kin and others did not. Mean annual reporting rates by group were physicians 130.1 (± 70.1), next-of-kin 29.3 (± 12.5), and others 10.4 (± 6.0). Prosecutions: The number of resulting criminal prosecutions increased significantly during the study period (slope 9.21, R² = 0.83, P < 0.001). The mean annual prosecution rate was 61.0 (± 33.6).

Conclusions

The reporting of patient deaths to the police by physicians increased significantly from 1998 to 2008 while those made by next-of-kin and others did not. The resulting criminal prosecutions of healthcare providers increased significantly during the same time period. The reasons for these increases are unclear and should be the focus of future research.

Food habits of Canadians: comparison of intakes in adults and adolescents to Canada's food guide to healthy eating

Over 25 years have elapsed since national food and nutrient intake data became available in Canada. Our goal was to describe present dietary intakes based on sociodemographic and 24-hour recall dietary interviews with adults and adolescents from households across the country. Within a multistage, stratified random sample of 80 enumeration areas, 1,543 randomly selected adults (aged 18-65) were enrolled in the study; 178 adolescents within the sampled households also participated. A comparison of food intake with Canada's Food Guide to Healthy Eating indicated that only males aged 13-34 met the minimum recommended intake levels for all four food groups. Mean milk products intake was below the minimum recommended level for all age groups of females and for men aged 35-65 years. Adolescent girls had low intakes of meat and alternatives. Daily grain product intakes were below five servings for women aged 50-65, as were vegetable and fruit intakes for women aged 18-40. Food choices from the "other foods" group contributed over 25% of energy and fat intake for all age and gender groups. These up-to-date data will be useful to dietitians, nutrition researchers, industry, and government in their efforts to promote Canadians' continued progress toward meeting food intake recommendations.

Food bank users: sociodemographic and nutritional characteristics

BACKGROUND

The continued expansion of food assistance programs makes it important to examine the sociodemographic characteristics and nutritional profiles of people relying on this service. The authors undertook such a study in a large urban centre.

METHODS

A total of 490 food bank users were randomly selected from a stratified random sample of 57 urban food banks in Montreal. A questionnaire and a dietary recall interview were given by a dietitian-interviewer to determine socioeconomic, demographic and cultural characteristics and macronutrient intake. These data were compared with national and provincial data.

RESULTS

The mean age of the participants (256 men and 234 women) was 41 years; 204 (41.6%) were living alone and most (409 [83.5%]) were receiving social assistance benefits. These food bank users were well educated (190 [38.8%] had completed technical school or had a college or university education), and the sample included few elderly or disabled people. The median body mass index was greater than 24, which indicated that energy intake, although below recommended levels, was not a chronic problem. The people using the food banks had a monthly shortfall in their food budget of between $43 and $46.

INTERPRETATION

Food banks are used regularly, primarily by young healthy adults. They are though of as a necessary community resource.