National survey of radiation doses of pediatric chest radiography in Korea: analysis of the factors affecting radiation doses

Typical Diagnostic Reference Levels of Radiation Exposure on Neonates Under 1 kg in Mobile Chest Imaging in Incubators

The purpose of this study is to determine the typical diagnostic reference levels (DRLs) of radiation exposure values for chest radiographs in neonates (<1 kg) in mobile imaging at a University Hospital in Greece and compare these values with the existing DRL values from the literature. Patient and dosimetry data, including age, sex, weight, tube voltage (kV), tube current (mA), exposure time (s), exposure index of a digital detector (S), and dose area product (DAP) were obtained from a total of 80 chest radiography examinations performed on neonates (<1 kg and <30 days old). All examinations were performed in a single X-ray system, and all data (demographic and dosimetry data) were collected from the PACS of the hospital. Typical radiation exposure values were determined as the median value of DAP and ESD distribution. Afterward, these typical values were compared with DRL values from other countries. Three radiologists reviewed the images to evaluate image quality for dose optimization in neonatal chest radiography. From all examinations, the mean value and standard deviation of DAP was 0.13 ± 0.11 dGy·cm2 (range: 0.01-0.46 dGy·cm2), and ESD was measured at 11.55 ± 4.96 μGy (range: 4.01-30.4 μGy). The typical values in terms of DAP and ESD were estimated to be 0.08 dGy·cm2 and 9.87 μGy, respectively. The results show that the DAP value decreases as the exposure index increases. This study's typical values were lower than the DRLs reported in the literature because our population had lower weight and age. From the subjective evaluation of image quality, it was revealed that the vast majority of radiographs (over 80%) met the criteria for being diagnostic as they received an excellent rating in terms of noise levels, contrast, and sharpness. This study contributes to the recording of typical dose values in a sensitive and rare category of patients (neonates weighing <1 kg) as well as information on the image quality of chest X-rays that were performed in this group.

Evaluation of the image quality and dose reduction in digital radiography with an advanced spatial noise reduction algorithm in pediatric patients

OBJECTIVES

To evaluate whether the advanced spatial noise reduction (ASNR) algorithm installed in a digital radiography system generates acceptable images at a lower dose than a conventional denoising algorithm in pediatric patients.

METHODS

Nine sets of 30 images of pediatric patients, classified under three protocols and three age groups, were retrospectively selected. Different levels of low-dose image sets of these 270 images were generated by a noise simulation tool after validation testing using phantoms. Each image set was obtained with both the ASNR and conventional algorithm, and grouped randomly and blinded. Three experienced pediatric radiologists were asked to pick the "image with optimum dose" among images of different dose levels with an ALARA (as low as reasonably achievable) perspective. Dose reduction rates for each protocol and age group were calculated, and entrance skin exposure (ESE) was calculated using the values of kVp and mAs, assuming a standard body depth for each age group.

RESULTS

With the ASNR algorithm, estimated dose reduction rates were highest for abdominal radiographs (45.0%, 27.3%, and 24.3% in infants, children, and adolescents, respectively, p < 0.001). The mean dose reductions for all age groups in the abdominal, chest, and skull radiographs were 32.8%, 12.9%, and 23.2%, respectively (p < 0.001). Average of the calculated ESE was lower with the ASNR algorithm than with the conventional algorithm group (p < 0.001).

CONCLUSIONS

The ASNR algorithm facilitated optimization of image quality with a higher reduction in radiation dose than the conventional algorithm, making it more acceptable for use in pediatric patients.

KEY POINTS

•ASNR algorithm in DR system improves image quality via enhanced contrast and noise removal by estimating actual noise distribution based on a multi-scale noise covariance and frequency processing. •Noise simulation tool (NST) generating images of different dose levels can be used for evaluation of the optimum dose without unnecessary additional radiation exposure to pediatric patients. •Retrospective clinical study using NST showed that the ASNR algorithm enabled a higher reduction in radiation dose than the conventional algorithm in pediatric patients.

Evaluation of Radiation Doses in Pediatric Patients Undergoing Conventional Chest X-ray Examination

ABSTRACT

This work deals with the evaluation of radiation doses from chest x rays for 240 male and female pediatric patients selected randomly from four Palestinian hospitals. The patient population was divided into five age groups: Newborn, 1, 5, 10, and 15 y old. Doses were theoretically calculated by using Monte Carlo based codes: CALDOSE-X5 and PCXMC-2.0. Patients' data and type of radiographic systems used as well as exposure factors were provided by the administrations of the selected hospitals. Absorbed organ doses from AP and PA projections were evaluated for 76 pediatric patients selected from one hospital in East Jerusalem. The highest mean organ dose for these patients was 0.085 mGy to the breast in AP projection. Effective doses were estimated for the five age groups for all patients. The highest average effective dose was found for patients in the age group of 10 y and was about 0.13 mSv, while the lowest average effective dose was found for the 5-y age group, about 0.06 mSv. The mean effective dose for all investigated patients in the five age categories was about 0.08 mSv. Variations in effective doses for the same age group and x-ray examination among involved hospitals are remarkable.

PROPOSAL FOR LOCAL DIAGNOSTIC REFERENCE LEVELS IN GENERAL RADIOGRAPHY IN JAPAN

The present study aimed to propose local diagnostic reference levels (DRLs) formulated by calculating entrance surface doses for general radiography at 20 facilities of Aichi prefecture in Japan, by comparing these values with DRLs established in Japan in 2015 (DRLs 2015) and assessing radiation dose differences among facilities. X-ray outputs (half-value layer and air kerma) of each facility were measured with a non-invasive type of detector. The results were employed to formulate local DRLs based on the 75th percentiles of dose distributions. These local DRLs were lower than the DRLs 2015 for all examinations. If proposed local DRLs from other 46 prefectures can be collected, this paper can be used to benefit the next effort to draft better DRL for Japan.

Assessment of Pediatrics Radiation Dose from Routine X-Ray Examination at Jimma University Hospital, Southwest Ethiopia

BACKGROUND

Given the fact that children are more sensitive to ionizing radiation than adults, with an increased risk of developing radiation-induced cancer, special care should be taken when they undergo X-ray examinations. The main aim of the current study was to determine Entrance Surface Dose (ESD) to pediatric patients arising from routine x-ray examination in the Radiology Department of Jimma University Specialized Hospital (JUSH).

METHODS

Descriptive cross-sectional study was conducted on pediatric patients less than 15 years of age who visited to seek x-ray examinations in JUSH. In this study, chest (AP), skull (AP), Abdomen (AP) and Pelvic (AP) x-ray examinations were analyzed. Radiographic exposure factors were recorded in each examination. ESD was calculated using exposure parameters. The calculated ESD values were weighed against the Diagnostic Reference Level (DRL) recommended doses and similar published studies. Comparison was made among different age groups through mean comparison.

RESULT

The obtained ESD values were mostly higher than the values in internationally published studies and DRL for all age groups. For chest AP, the mean ESD values were 1.82mGy which is higher than similar studies in Nigeria (0.642Mgy), Brazil (o.o62mGy) and NRPB (0.050mGy) for ages of 0-1 years.

CONCLUSION

The higher pediatric patient dose obtained in this study is a further indicator that doses delivered to pediatric patients are not according to ALARA principle, and there is a need to optimize service and patients' radiation exposure in JUSH in particular and in Ethiopia in general.

Survey of Thoracic CT Protocols and Technical Parameters in Korean Hospitals: Changes before and after Establishment of Thoracic CT Guideline by Korean Society of Thoracic Radiology in 2008

We retrospectively reviewed the thoracic CT scan protocols and technical parameters obtained from hospitals in Korea, one group during May 2007 (n = 100) and the other group during January 2012 (n = 173), before and after the establishment of the thoracic CT Guideline in 2008. Each group was also divided into two subgroups according to the health care delivery level, i.e. the "A" subgroup from primary and the "B" subgroup from secondary and tertiary care hospitals. When comparing the data from 2007 and 2012, the tube current decreased from 179.1 mAs to 137.2 mAs. The scan interval decreased from 6.4 mm to 4.8 mm. Also, the insufficient scan range decreased from 19.0% to 8.7%, and the suboptimal quality scans decreased from 33.0% to 5.2%. Between groups A and B, group B had lower tube voltages, smaller scan thicknesses, and smaller scan intervals. However, group B had more phase numbers. In terms of the suboptimal quality scans, a decrease was seen in both groups. In conclusion, during the five-year time period between 2007 and 2012, a reduction in the tube current values was seen. And the overall image quality improved over the same time period. We assume that these changes are attributed to the implementation of the thoracic CT guideline in 2008.

Spina bifida occulta: not to be overlooked in children with nocturnal enuresis

OBJECTIVE

Previous reports have suggested that the incidence of spina bifida occulta in patients with nocturnal enuresis is higher than in the general population. However, the effect of spina bifida occulta on the response to nocturnal enuresis treatment is controversial. The purpose of this study was to investigate the relationship between spina bifida occulta and response to treatment of nocturnal enuresis.

METHODS

Between 2006 and 2009, the records of 160 children with nocturnal enuresis were reviewed. Children with other organic urological disease or symptoms suggestive of spinal dysraphism were excluded. Plain radiography for the kidney-ureter-bladder was carried out before the start of the nocturnal enuresis treatment. Response to treatment of children with and without spina bifida occulta was compared.

RESULTS

Of 160 children, 53 were girls; the mean age was 7.8 ± 2.06 years. The mean duration of treatment was 8.7 ± 9.29 months. Spina bifida occulta was detected in 43 children (26.9%). Spina bifida occulta affected L4 in four children, L5 in 12 children, S1 in 26 children and S2 in one child. There was a significant difference between the spina bifida occulta and non-spina bifida occulta groups in terms of outcome (P=0.002), with a complete response more likely in children without spina bifida occulta (P=0.005). None of the children with primary non-mono symptomatic nocturnal enuresis and spina bifida occulta showed a complete response.

CONCLUSIONS

The presence of spina bifida occulta significantly affects the response to treatment in patients with nocturnal enuresis. Thus, verifying spina bifida occulta in this patient population can facilitate the prediction of the response to nocturnal enuresis treatment.