Radiation dose features and solid cancer induction in pediatric computed tomography

Post-Procedural Follow-Up of the Interventional Radiology’s Management of Osteoid Osteomas and Osteoblastomas

The family of painful osteocytic tumors includes osteoblastomas and osteoid osteomas—these lesions are considered benign, but they could produce a significant painful symptomatology. Usually, people affected are between 20 s and 30 s. When symptomatic, an effective treatment is mandatory for the management of these lesions to allow for a ful quality of life. The possibilities of treatment range from chirurgical en-block resection (procedure of surgical oncology aiming to remove a tumoral mass in its entirety, completely surrounded by a continuous layer of healthy tissue) to interventional approaches that, nowadays, are considered the most affordable and sustainable in terms of effectiveness, recovery after procedure, and for bone structure sparing. The main techniques used for osteoid osteomas and osteoblastomas are radio frequency ablation (RFA) and magnetic resonance-guided focused ultrasound (MRgFUS): the most important difference between these approaches is the needleless approach of MRgFUS, which further reduces the minimal invasiveness of RFA (and the related consequences) and the absence of exposure to ionizing radiation. Despite their high efficacy, a recurrence of pathology may occur due to a failure in therapy. In light of this, describing the various possibilities of follow up protocols and the imaging aspects of recurrence or incomplete treatment is mandatory. In the scenario given in the literature, many authors have tried to asses an organized follow up protocol of these patients, but many of them did not undergo periodical magnetic resonance (MR) or computerized tomography (CT) because of the lack of symptomatology. However, even if it seems that clinical evolution is central, different papers describe the protocol useful to detect eventual relapse. The aim of our manuscript is to review the various possibilities of follow-up of these patients and to bring together the most salient aspects found during the management of these osteocytic bone lesions.

Improving the protocol for whole-body CT scans in trauma patients

PURPOSE

While whole-body computed tomography is an established diagnostic method for the work up of polytraumatized patients, the protocols used differ between trauma centers. This study aimed to compare scan duration and estimated radiation of two protocols. Secondary aim was to assess if using the revised CT protocol reduced the number of additional images of the upper extremities.

METHODS

Two groups of consecutive trauma patients, which both received a whole-body CT, were analyzed. Patients, who received a three-phased CT during which their arms needed to be repositioned from their side to above the head, were assigned to group A. Those, who received a CT with their arms placed on a pillow ventral to the abdomen throughout the entire scan were assigned to group B. Estimated radiation dose, scan duration, number of upper limb injuries and number of additional images of the upper limbs within 24 h after initial CT were assessed.

RESULTS

Group A consisted of 182 patients, group B of 218. The scan duration was 3 min shorter (p < 0.001) and the estimated radiation dose lower (15.0 vs 22.9 mSv, p < 0.001) in group B. There was no difference in the number of upper limb injuries detected or the number of upper limb additional images required within 24 h.

CONCLUSION

Using a whole-body CT scan protocol in which the arms remain on a pillow ventral to the torso instead of one which requires a repositioning of the arms, both scan duration and estimated radiation dose can be reduced. Despite the arms being within the scanned area in the revised protocol, the number of additional imaging of the upper extremities could not be reduced.

Experimental Assessment of Workplace Radiation Exposure in Diagnostic X-ray Medical Imaging Centres in Benin from 2019 to 2020

The ease of prescribing radiological examinations has prompted an expansion in radiological procedures and, consequently, an increase of occupational dose to medical imaging workers. However, little is known about radiation exposure in the workplace of medical radiology professionals in many countries, and in Benin particularly. The purpose of this study was to assess ambient radiation doses in diagnostic X-ray medical facilities in Benin and to observe whether exposure levels are below reference levels. A total of 72 public and private medical imaging centres participated in a cross-sectional study carried out from June 2019 to February 2020 in Benin. These centres had 59 X-ray, four chest and six computed tomography (CT) scan rooms. A calibrated radiameter able to measure short, pulsed or continuous X fields and gamma/beta (50 nSv to 10 Sv) was used to measure exposure levels in these functional rooms. Scattered X-ray doses and exposure time from radiological examinations both behind the lead glass of the control area to assess the levels of exposure of professionals and outside of the examination room to evaluate the level of exposure of the public (including non-exposed workers) have been provided. Equivalent doses estimated per hour were compared with the reference levels of 7.50 and 0.05 µSv per hour for workers and the public, respectively. At the control area, the mean/median (min-max) equivalent doses were 0.09/0.07 (0.00-0.21), 2.39/0.13 (0.00-75.67), and 228.39/28.65 (0.39-869.75) µSv per hour for the chest, X-ray, and CT-scan rooms, respectively. Among 69 examination rooms, 13.04% of the equivalent dose estimated in the workplace behind the lead glass was greater than 7.50 µSv per hour; 65 out of 69 examination rooms showed that 40.00% of the equivalent dose estimated behind the doors was greater than 0.05 µSv per hour. These results demonstrated that current controls, including leaded glass separating the control panel and leaded doors between the examination room and the corridor, are inadequate to limit radiation exposures. The controls must be upgraded and a dosimetry program should be implemented to monitor exposures of employees, patients, and visitors.

Clinical significance of rib fractures' anatomical patterns

OBJECTIVES

Rib fractures are common and carry significant morbidity. Chest CT provides an accurate mapping of the fractures. The aim of this study is to propose an anatomical classification of rib fractures, and assess their relation to complication development.

METHOD

The records of all blunt trauma patients between January 1st 2014 and December 31st 2017 at a university hospital were retrospectively reviewed. Wounded who were hospitalized with rib fractures (two and more) as the primary injury were included in the study. Based on the chest CT scans, the cohort was divided into five groups: upper ribs (1-4) fractures, anterior, lateral and posterior middle ribs (4-7) fractures, and lower ribs (9-12) fractures. Data regarding demographics, complications (pneumothorax, hemothorax, chest drains, pulmonary contusion atelectasis, pneumonia, respiratory failure and death), intensive care admission and hospital stay were collected.

RESULTS

A total of 102 wounded were included in the study, with a mean age of 46.3 years. The mean number of fractured ribs per person was 3.82±1.68, and 46 wounded had displaced fractures. Rib fracture distribution was: upper ribs - 13.7%, anterior middle ribs - 28.5%, lateral middle ribs fractures - 27.5%, posterior middle ribs - 14.7%, lower ribs fractures - 15.7%. Wounded sustaining lateral middle ribs fractures had the highest complications rates in relation to any other fracture location group, with 25% respiratory failure rate.

CONCLUSIONS

Lateral middle ribs fractures are associated with a higher complication rate and may require closer oabservation.

RISK EVALUATION IN THE LOW-DOSE RANGE CT FOR RADIATION-EXPOSED CHILDREN, BASED ON DNA DAMAGE

One of the most common usages of radiation in current medical diagnosis is computed tomography (CT) using X-rays. The potential health risk of CT scans has been discussed in various studies to determine whether low-dose radiation from CT could enhance the chromosome aberration yields in pediatric patients and increase their risk of carcinogenesis. For this reason, it is of great interest to study the effects of low-dose radiation. The induction of DNA damage by a CT scan examination has been demonstrated in several reports by the γ-H2AX assay, the micronuclei assay and dicentrics measurements. However, the results of most studies showed limitations. On the other hand, epidemiological studies give contradictory results for post-natal radiation exposure in the low-dose range, so it is still difficult to draw conclusions about the effects of CT examinations and risk of carcinogenesis. This article provides an overview of previously published data and summarizes the current state of knowledge.

Whole-Body Computed Tomography Using Low-Dose Biphasic Injection Protocol With Adaptive Statistical Iterative Reconstruction V: Assessment of Dose Reduction and Image Quality in Trauma Patients

AIM

This study aimed to evaluate potential dose savings on a revised protocol for whole-body computed tomography and image quality after implementing Adaptive Statistical Iterative Reconstruction V (ASiR-V) algorism for trauma patients and compare it with routine protocol.

MATERIALS AND METHODS

One hundred trauma patients were classified into 2 groups using 2 different scanning protocols. Group A (n = 50; age, 32.48 ± 8.09 years) underwent routine 3-phase protocol. Group B (n = 50; age, 35.94 ± 13.57 years) underwent biphasic injection protocol including unenhanced scan for the brain and cervical spines, followed by a 1-step acquisition of the thorax, abdomen, and pelvis. The ASiR-V level was kept at 50% for all examinations, and then studies were reconstructed at 0% ASiR-V level. Radiation dose, total acquisition time, and image count were compared between groups (A and B). Two radiologists independently graded image quality and artifacts between both groups and 2 ASiR-V levels (0 and 50%).

RESULTS

The mean (±SD) dose-length product value for postcontrast scans in group A was 1602.3 ± 271.8 mGy · cm and higher when compared with group B (P < 0.001), which was 951.1 ± 359.6 mGy · cm. Biphasic injection protocol gave a dose reduction of 40.4% and reduced the total acquisition time by 11.4% and image count by 37.6%. There was no statistically significant difference between the image quality scores for both groups; however, group A scored higher grades (4.62 ± 0.56 and 4.56 ± 0.67). Similarly, the image quality scores for both ASiR-V levels in both groups were not significantly different.

CONCLUSIONS

Biphasic computed tomography protocol reduced radiation dose with maintenance of diagnostic accuracy and image quality after implementing ASiR-V algorism.

Magnetic Resonance Imaging-guided High-intensity Focused Ultrasound Applications in Pediatrics: Early Experience at Children's National Medical Center

Magnetic resonance imaging-guided high-intensity focused ultrasound (MR-HIFU) is a novel technology that integrates magnetic resonance imaging with therapeutic ultrasound. This unique approach provides a completely noninvasive method for precise thermal ablation of targeted tissues with real-time imaging feedback. Over the past 2 decades, MR-HIFU has shown clinical success in several adult applications ranging from treatment of painful bone metastases to uterine fibroids to prostate cancer and essential tremor. Although clinical experience in pediatrics is relatively small, the advantages of a completely noninvasive and radiation-free therapy are especially attractive to growing children. Unlike elderly patients, young children must deal with an entire lifetime of negative effects related to collateral tissue damage associated with invasive surgery, side effects of chemotherapy, and risk of secondary malignancy due to radiation exposure. These reasons provide a clear rationale and strong motivation to further advance clinical utility of MR-HIFU in pediatrics. We begin with an introduction to MR-HIFU technology and the clinical experience in adults. We then describe our early institutional experience in using MR-HIFU ablation to treat symptomatic benign, locally aggressive, and metastatic tumors in children and young adults. We also review some limitations and challenges encountered in treating pediatric patients and highlight additional pediatric applications which may be feasible in the near future.

Radiological Correlates of Raised Intracranial Pressure in Children: A Review

Radiological assessment of the head is a routine part of the management of traumatic brain injury. This assessment can help to determine the requirement for invasive intracranial pressure (ICP) monitoring. The radiological correlates of elevated ICP have been widely studied in adults but far fewer specific pediatric studies have been conducted. There is, however, growing evidence that there are important differences in the radiological presentations of elevated ICP between children and adults; a reflection of the anatomical and physiological differences, as well as a difference in the pathophysiology of brain injury in children. Here in, we review the radiological parameters that correspond with increased ICP in children that have been described in the literature. We then describe the future directions of this work and our recommendations in order to develop non-invasive and radiological markers of raised ICP in children.

Radiation Exposure and Attributable Cancer Risk in Patients With Esophageal Atresia

OBJECTIVES

Cases of esophageal carcinoma have been documented in survivors of esophageal atresia (EA). Children with EA undergo considerable amounts of diagnostic imaging and consequent radiation exposure potentially increasing their lifetime cancer mortality risk. This study evaluates the radiological procedures performed on patients with EA and estimates their cumulative radiation exposure and attributable lifetime cancer mortality risk.

METHODS

Medical records of patients with EA managed at a tertiary care center were reviewed for demographics, EA subtype, and number and type of radiological investigations. Existing normative data were used to estimate the cumulative radiation exposure and lifetime cancer risk per patient.

RESULTS

The present study included 53 patients with a mean follow-up of 5.7 years. The overall median and maximum estimated effective radiation dose in the neonatal period was 5521.4 μSv/patient and 66638.6 μSv/patient, respectively. This correlates to a median and maximum estimated cumulative lifetime cancer mortality risk of 1:1530 and 1:130, respectively. Hence, radiation exposure in the neonatal period increased the cumulative cancer mortality risk a median of 130-fold and a maximum of 1575-fold in EA survivors.

CONCLUSIONS

Children with EA are exposed to significant amounts of radiation and an increased estimated cumulative cancer mortality risk. Efforts should be made to eliminate superfluous imaging.

Comparison of Noninvasive High-Intensity Focused Ultrasound with Radiofrequency Ablation of Osteoid Osteoma

OBJECTIVE

To evaluate clinical feasibility and safety of magnetic resonance imaging-guided high-intensity focused ultrasound (MR-HIFU) treatment of symptomatic osteoid osteoma and to compare clinical response with standard of care treatment.

STUDY DESIGN

Nine subjects with radiologically confirmed, symptomatic osteoid osteoma were treated with MR-HIFU in an institutional review board-approved clinical trial. Treatment feasibility and safety were assessed. Clinical response was evaluated in terms of analgesic requirement, visual analog scale pain score, and sleep quality. Anesthesia, procedure, and recovery times were recorded. This MR-HIFU group was compared with a historical control group of 9 consecutive patients treated with radiofrequency ablation.

RESULTS

Nine subjects (7 male, 2 female; 16 ± 6 years) were treated with MR-HIFU without technical difficulties or any serious adverse events. There was significant decrease in their median pain scores 4 weeks within treatment (6 vs 0, P < .01). Total pain resolution and cessation of analgesics were achieved in 8 of 9 patients after 4 weeks. In the radiofrequency ablation group, 9 patients (8 male, 1 female; 10 ± 6 years) were treated in routine clinical practice. All 9 demonstrated complete pain resolution and cessation of medications by 4 weeks with a significant decrease in median pain scores (9 vs 0, P < .001). One developed a second-degree skin burn, but there were no other adverse events. Procedure times and treatment charges were comparable between the 2 groups.

CONCLUSION

This pilot study shows that MR-HIFU treatment of osteoid osteoma refractory to medical therapy is feasible and can be performed safely in pediatric patients. Clinical response is comparable with standard of care treatment but without any incisions or exposure to ionizing radiation.

TRIAL REGISTRATION

ClinicalTrials.govNCT02349971.

Toward a Framework for Benefit-Risk Assessment in Diagnostic Imaging: Identifying Scenario-specific Criteria

RATIONALE AND OBJECTIVES

Diagnostic imaging has many effects and there is no common definition of value in diagnostic radiology. As benefit-risk trade-offs are rarely made explicit, it is not clear which framework is used in clinical guideline development. We describe initial steps toward the creation of a benefit-risk framework for diagnostic radiology.

MATERIALS AND METHODS

We performed a literature search and an online survey of physicians to identify and collect benefit-risk criteria (BRC) relevant to diagnostic imaging tests. We operationalized a process for selection of BRC with the use of four clinical use case scenarios that vary by diagnostic alternatives and clinical indication. Respondent BRC selections were compared across clinical scenarios and between radiologists and nonradiologists.

RESULTS

Thirty-six BRC were identified and organized into three domains: (1) those that account for differences attributable only to the test or device (n = 17); (2) those that account for clinical management and provider experiences (n = 12); and (3) those that capture patient experience (n = 7). Forty-eight survey participants selected 22 criteria from the initial list in the survey (9-11 per case). Engaging ordering physicians increased the number of criteria selected in each of the four clinical scenarios presented. We developed a process for standardizing selection of BRC in guideline development.

CONCLUSION

These results suggest that a process relying on elements of comparative effectiveness and the use of standardized BRC may ensure consistent examination of differences among alternatives by way of making explicit implicit trade-offs that otherwise enter the decision-making space and detract from consistency and transparency. These findings also highlight the need for multidisciplinary teams that include input from ordering physicians.

A new low-dose multi-phase trauma CT protocol and its impact on diagnostic assessment and radiation dose in multi-trauma patients

Purpose

Computed tomography (CT) examinations, often using high-radiation dosages, are increasingly used in the acute management of polytrauma patients. This study compares a low-dose polytrauma multi-phase whole-body CT (WBCT) protocol on a latest generation of 16-cm detector 258-slice multi-detector CT (MDCT) scanner with advanced dose reduction techniques to a single-phase polytrauma WBCT protocol on a 64-slice MDCT scanner.

Methods

Between March and September 2015, 109 polytrauma patients (group A) underwent acute WBCT with a low-dose multi-phase WBCT protocol on a 258-slice MDCT whereas 110 polytrauma patients (group B) underwent single-phase trauma CT on a 64-slice MDCT. The diagnostic accuracy to trauma-related injuries, radiation dose, quantitative and semiquantitative image quality parameters, subjective image quality scorings, and workflow time parameters were compared.

Results

In group A, statistically significantly more arterial injuries (p = 0.04) and arterial dissections (p = 0.002) were detected. In group A, the mean (±SD) dose length product value was 1681 ± 183 mGy*cm and markedly lower when compared to group B (p < 0.001). The SDs of the mean Houndsfield unit values of the brain, liver, and abdominal aorta were lower in group A (p < 0.001). Mean signal-to-noise ratios (SNRs) for the brain, liver, and abdominal aorta were significantly higher in group A (p < 0.001). Group A had significantly higher image quality scores for all analyzed anatomical locations (p < 0.02). However, the mean time from patient registration until completion of examination was significantly longer for group A (p < 0.001).

Conclusions

The low-dose multi-phase CT protocol improves diagnostic accuracy and image quality at markedly reduced radiation. However, due to technical complexities and surplus electronic data provided by the newer low-dose technique, examination time increases, which reduces workflow in acute emergency situations.

Non-invasive intracranial pressure assessment

Assessing intracranial pressure (ICP) remains a cornerstone in neurosurgical care. Invasive techniques for monitoring ICP remain the gold standard. The need for a reliable, safe and reproducible technique to non-invasively assess ICP in the context of early screening and in the neurocritical care environment is obvious. Numerous techniques have been described with several novel advances. While none of the currently available techniques appear independently accurate enough to quantify raised ICP, there is some promising work being undertaken.

Noninvasive methods of detecting increased intracranial pressure

The detection of elevated intracranial pressure (ICP) is of paramount importance in the diagnosis and management of a number of neurologic pathologies. The current gold standard is the use of intraventricular or intraparenchymal catheters; however, this is invasive, expensive, and requires anesthesia. On the other hand, diagnosing intracranial hypertension based on clinical symptoms such as headaches, vomiting, and visual changes lacks sensitivity. As such, there exists a need for a noninvasive yet accurate and reliable method for detecting elevated ICP. In this review, we aim to cover both structural modalities such as computed tomography (CT), magnetic resonance imaging (MRI), ocular ultrasound, fundoscopy, and optical coherence tomography (OCT) as well as functional modalities such as transcranial Doppler ultrasound (TCD), visual evoked potentials (VEPs), and near-infrared spectroscopy (NIRS).

[Papillary thyroid carcinoma in a child with congenital dyshormonogenetic hypothyroidism. Case report]

INTRODUCTION

Papillary thyroid carcinoma (PTC) is a rare childhood disease. The development of PTC in dyshormonogenetic congenital hypothyroidism (CH) is infrequent, with very few case reports in literature.

OBJECTIVE

To report a case of PTC in a boy with dyshormonogenetic CH without goitre and exposed to ionising radiation. To evaluate relationships between these factors and development of PTC.

CASE REPORT

We present a boy with dyshormonogenetic CH since birth. Early hormonal substitution was initiated, with subsequent normal levels of thyrotropin and thyroid hormones. He has also congenital cardiomyopathy, exposed to interventional treatment with 10 heart catheterisations, and approximately 26 chest X-rays at paediatric doses. A thyroid nodule was found in thyroid echography at the age of 6 years old. Fine needle aspiration biopsy confirmed high probability of thyroid carcinoma (Bethesda 5). The pre-surgical thorax and cerebral scan showed no evidence of metastasis. The patient underwent total thyroidectomy. Pathological examination revealed a 0.5cm papillary thyroid micro-carcinoma in the right lobe, with no evidence of dissemination.

CONCLUSION

Genetic mutations and radiation exposure may play an important role in the development of PTC. There may be common pathways between dyshormonogenetic CH and thyroid carcinoma that need further investigation.

Exposure Risks Among Children Undergoing Radiation Therapy: Considerations in the Era of Image Guided Radiation Therapy

Recent improvements in toxicity profiles of pediatric oncology patients are attributable, in part, to advances in the field of radiation oncology such as intensity modulated radiation (IMRT) and proton therapy (IMPT). While IMRT and IMPT deliver highly conformal dose to targeted volumes, they commonly demand the addition of 2- or 3-dimensional imaging for precise positioning--a technique known as image guided radiation therapy (IGRT). In this manuscript we address strategies to further minimize exposure risk in children by reducing effective IGRT dose. Portal X rays and cone beam computed tomography (CBCT) are commonly used to verify patient position during IGRT and, because their relative radiation exposure is far less than the radiation absorbed from therapeutic treatment beams, their sometimes significant contribution to cumulative risk can be easily overlooked. Optimizing the conformality of IMRT/IMPT while simultaneously ignoring IGRT dose may result in organs at risk being exposed to a greater proportion of radiation from IGRT than from therapeutic beams. Over a treatment course, cumulative central-axis CBCT effective dose can approach or supersede the amount of radiation absorbed from a single treatment fraction, a theoretical increase of 3% to 5% in mutagenic risk. In select scenarios, this may result in the underprediction of acute and late toxicity risk (such as azoospermia, ovarian dysfunction, or increased lifetime mutagenic risk) in radiation-sensitive organs and patients. Although dependent on variables such as patient age, gender, weight, body habitus, anatomic location, and dose-toxicity thresholds, modifying IGRT use and acquisition parameters such as frequency, imaging modality, beam energy, current, voltage, rotational degree, collimation, field size, reconstruction algorithm, and documentation can reduce exposure, avoid unnecessary toxicity, and achieve doses as low as reasonably achievable, promoting a culture and practice of "gentle IGRT."

Breast Cancer Induced by X-Ray Mammography Screening? A Review Based on Recent Understanding of Low-Dose Radiobiology

Screening mammography offers the possibility of discovering malignant diseases at an early stage, which is consequently treated early, thereby reducing the mortality rate. However, ionizing radiation as used in low-dose X-ray mammography may be associated with a risk of radiation-induced carcinogenesis. In the context of the harmful effects of ionizing radiation, this article reviewed novel radiobiological data and provided a simulation of the relative incidence of radiation-induced breast cancer due to screening against a background baseline incidence in a population of 100,000 individuals. The use of modern digital mammographic technology was assumed, giving rise to a glandular dose of 2.5 mGy from a 2-view per breast image. Assuming no latency time, this led to a ratio of induced incidence rate over baseline incidence rate of about 1.6‰ for biennial screening in women aged 50-74 years, although it cannot be excluded that the dose and dose rate effectiveness factor values relying on new radiobiological insights may lower this number to about 0.7‰. This carcinogenic risk is considered small in relation to the potential beneficial effects of screening, especially as latency time was not taken into consideration. However, individuals who are known to be carriers of risk-increasing genetic variations and/or have an inherited disposition of breast cancer should avoid ionizing radiation as much as possible and should be referred to ultrasound or magnetic resonance imaging. In addition, a significant, but difficult to quantify, risk of cancer is present for individuals who suffer from hypersusceptibility to ionizing radiation.

Connexin-Related (DFNB1) Hearing Loss

Objectives

Determine if routine computed tomography (CT) imaging is necessary in the workup for children with connexin-related (DFNB1) sensorineural hearing loss (SNHL).

Study Design

Case-control retrospective chart and imaging review.

Setting

Tertiary care otolaryngology practice.

Subjects and Methods

High-resolution temporal bone CT scans of children (n = 21) with DFNB1 SNHL were compared to age-matched controls with either conductive hearing loss (CHL, n = 33) or a nonsyndromic, non-DFNB1 SNHL (n = 33). Sixteen measurements of cochleo-vestibular structures were recorded. Statistical analysis was performed using a repeated analysis of variance model that controlled for both age and gender. Area under the curve (AUC) and multidimensional AUC (MAUC) analyses were also performed.

Results

Overall, no statistically significant differences were found between the 3 experimental groups. In addition, comparisons between the DFNB1 and CHL groups, DFNB1 and non-DFNB1 SNHL groups, and CHL and non-DFNB1 SNHL groups failed to demonstrate any statistically significant differences. AUC and MAUC analyses also failed to detect any significant differences between the 3 groups.

Conclusions

Patients with DFNB1 SNHL do not have significant anatomic differences on temporal bone CT scans when compared to non-DFNB1 SNHL and CHL control groups. Based on the above analysis, it is reasonable to avoid routine CT imaging of the temporal bones in children with known DFNB1 SNHL unless otherwise clinically indicated.

Optimizing the balance between radiation dose and image quality in pediatric head CT: findings before and after intensive radiologic staff training

OBJECTIVE

The purpose of this study was to assess the radiation dose and image quality of pediatric head CT examinations before and after radiologic staff training.

MATERIALS AND METHODS

Outpatients 1 month to 14 years old underwent 215 unenhanced head CT examinations before and after intensive training of staff radiologists and technologists in optimization of CT technique. Patients were divided into three age groups (0-4, 5-9, and 10-14 years), and CT dose index, dose-length product, tube voltage, and tube current-rotation time product values before and after training were retrieved from the hospital PACS. Gray matter conspicuity and contrast-to-noise ratio before and after training were calculated, and subjective image quality in terms of artifacts, gray-white matter differentiation, noise, visualization of posterior fossa structures, and need for repeat CT examination was visually evaluated by three neuroradiologists.

RESULTS

The median CT dose index and dose-length product values were significantly lower after than before training in all age groups (27 mGy and 338 mGy ∙ cm vs 107 mGy and 1444 mGy ∙ cm in the 0- to 4-year-old group, 41 mGy and 483 mGy ∙ cm vs 68 mGy and 976 mGy ∙ cm in the 5- to 9-year-old group, and 51 mGy and 679 mGy ∙ cm vs 107 mGy and 1480 mGy ∙ cm in the 10- to 14-year-old group; p < 0.001). The tube voltage and tube current-time values after training were significantly lower than the levels before training (p < 0.001). Subjective posttraining image quality was not inferior to pretraining levels for any item except noise (p < 0.05), which, however, was never diagnostically unacceptable.

CONCLUSION

Radiologic staff training can be effective in reducing radiation dose while preserving diagnostic image quality in pediatric head CT examinations.

Nuking the radiation: minimizing radiation exposure in the evaluation of pediatric blunt trauma

PURPOSE OF REVIEW

Our objective is to highlight recent literature investigating low-radiation diagnostic strategies in the evaluation of pediatric trauma.

RECENT FINDINGS

In the area of minor head injury, research has focused on implementation of validated clinical decision rules into practice to reduce unnecessary computed tomography scans. Clinical observation may also serve as an adjunct to initial assessment and a potential substitute for computed tomography imaging. Subgroups of children with special needs or severe injury mechanisms may also be safely characterized by the clinical decision rule and spared radiation exposure. Physical examination techniques may be useful in diagnosing mandibular fractures. In addition, evidence suggests that plain radiography for evaluation of blunt thoracic trauma may be sufficient in many cases, and computed tomography could be reserved for those with abnormal radiographs, high-risk mechanisms, or abnormal physical findings. Clinical decision rules are able to predict intra-abdominal injury with high sensitivity. Data suggest that skeletal surveys may be modified to limit radiation exposure in the case of suspected nonaccidental trauma.

SUMMARY

More research is needed in development of pediatric-specific clinical decision rules and risk stratification and in testing low-radiation diagnostic modalities in the pediatric trauma population.

Radiation risks associated with serial imaging in colorectal cancer patients: Should we worry?

To provide an overview of the radiation related cancer risk associated with multiple computed tomographic scans required for follow up in colorectal cancer patients. A literature search of the PubMed and Cochrane Library databases was carried out and limited to the last 10 years from December 2012. Inclusion criteria were studies where computed tomographic scans or radiation from other medical imaging modalities were used and the risks associated with ionizing radiation reported. Thirty-six studies were included for appraisal with no randomized controlled trials. Thirty-four of the thirty-six studies showed a positive association between medical imaging radiation and increased risk of cancer. The radiation dose absorbed and cancer risk was greater in children and young adults than in older patients. Most studies included in the review used a linear, no-threshold model to calculate cancer risks and this may not be applicable at low radiation doses. Many studies are retrospective and ensuring complete follow up on thousands of patients is difficult. There was a minor increased risk of cancer from ionizing radiation in medical imaging studies. The radiation risks of low dose exposure (< 50 milli-Sieverts) are uncertain. A clinically justified scan in the context of colorectal cancer is likely to provide more benefits than harm but current guidelines for patient follow up will need to be revised to accommodate a more aggressive approach to treating metastatic disease.

Occupational radiation exposure among the staff of departments of nuclear medicine and diagnostic radiology in Kuwait

OBJECTIVES

To investigate radiation exposure among the staff of departments of nuclear medicine (NM) and diagnostic radiology (DR) during 2008 and 2009 and to compare the mean doses received with the limit of 20 mSv/year of the International Commission of Radiological Protection (ICRP).

MATERIALS AND METHODS

The whole-body dose or effective dose, i.e. Hp(10), and the skin dose, i.e. Hp(0.07), of the staff of departments of NM and DR in Kuwait for the period of 2008 and 2009 were taken from the national thermoluminescent dosimetry database. A total of 1,780 radiation workers, grouped as NM physicians, radiologists, NM technologists, and DR technologists, from 7 departments of NM and 12 departments of DR were included. The annual average Hp(10) and Hp(0.07) were calculated for each group and comparisons were made between the groups and the years. A two-sided Mann-Whitney test was carried out, at the p = 0.05 level, to compare the means. The mean Hp(10) was compared with the limits of the ICRP.

RESULTS

Of the 16 distributions of Hp(10) and Hp(0.07), 10 were normal, with a mean annual Hp (10) in 2008 of 1.06, 1.03, 1.07, and 1.05 mSv for NM physicians, radiologists, NM technologists, and DR technologists, respectively. The corresponding Hp(0.07) values for 2008 were 1.03, 1.00, 1.05, and 1.03 mSv, respectively. Small but significant (p < 0.001) reductions in Hp(10) and Hp(0.07) were observed in 2009 for NM technologists and DR technologists. In all other cases, no significant (p > 0.072) differences were found.

CONCLUSION

The annual average Hp(10) was well below the limit of the ICRP.