Helical CT of the body: are settings adjusted for pediatric patients?

Left ventricle volume measurements in cardiac micro-CT: the impact of radiation dose and contrast agent

Micro-CT-based cardiac function estimation in small animals requires measurement of left ventricle (LV) volume at multiple time points during the cardiac cycle. Measurement accuracy depends on the image resolution, its signal and noise properties, and the analysis procedure. This work compares the accuracy of the Otsu thresholding and a region sampled binary mixture approach, for live mouse LV volume measurement using 100 microm resolution datasets. We evaluate both analysis methods after varying the volume of injected contrast agent and the number of projections used for CT reconstruction with a goal of permitting reduced levels of both X-ray and contrast agent doses.

Cancer risks from diagnostic radiology

In recent years, there has been a rapid increase in the number of CT scans performed, both in the US and the UK, which has fuelled concern about the long-term consequences of these exposures, particularly in terms of cancer induction. Statistics from the US and the UK indicate a 20-fold and 12-fold increase, respectively, in CT usage over the past two decades, with per caput CT usage in the US being about five times that in the UK. In both countries, most of the collective dose from diagnostic radiology comes from high-dose (in the radiological context) procedures such as CT, interventional radiology and barium enemas; for these procedures, the relevant organ doses are in the range for which there is now direct credible epidemiological evidence of an excess risk of cancer, without the need to extrapolate risks from higher doses. Even for high-dose radiological procedures, the risk to the individual patient is small, so that the benefit/risk balance is generally in the patients' favour. Concerns arise when CT examinations are used without a proven clinical rationale, when alternative modalities could be used with equal efficacy, or when CT scans are repeated unnecessarily. It has been estimated, at least in the US, that these scenarios account for up to one-third of all CT scans. A further issue is the increasing use of CT scans as a screening procedure in asymptomatic patients; at this time, the benefit/risk balance for any of the commonly suggested CT screening techniques has yet to be established.

Imaging findings in noncraniofacial childhood rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most common soft-tissue sarcoma of childhood. This paper is focuses on imaging for diagnosis, staging, and follow-up of noncraniofacial RMS.

Pediatric traumatic brain injury: an update of research to understand and improve outcomes

PURPOSE OF REVIEW

Traumatic brain injury is the leading cause of death in the pediatric population. The purpose of this review is to highlight recent contributions in evaluation, management, and predictors of outcome in pediatric traumatic brain injury.

RECENT FINDINGS

Advances have been made in defining the critical Glasgow Coma Score for predicting poor outcome and in developing the Relative Head Injury Severity Score, which can assess severity of traumatic brain injury from administrative datasets. More information regarding the radiation risks of head computed tomography imaging and guidelines for the appropriate use of imaging have recently been evaluated. Important steps have also been taken to reduce secondary brain injury through the use of hypertonic saline and induced hypothermia. There continues to be long-term neurodevelopmental deficits among survivors and new tools to assess these deficits have been developed and tested. Finally, increased investigation into understanding the impact of minority race and socioeconomic status has on outcome following traumatic brain injury has determined the existence of disturbing disparities.

SUMMARY

Traumatic brain injury is the leading cause of mortality and is a major public health issue in the pediatric population. There have been many recent contributions in the diagnosis, treatment, and long-term morbidity of traumatic brain injury. Ongoing work is needed to improve outcomes of traumatic brain injury equitably for all patients.

ALARA: is there a cause for alarm? Reducing radiation risks from computed tomography scanning in children

PURPOSE OF REVIEW

Radiation exposure from computed tomography is associated with a small but significant increase in risk for fatal cancer over a child's lifetime. This review aims to heighten awareness and spearhead efforts to reduce unnecessary computed tomography scans in children.

RECENT FINDINGS

The use of pediatric computed tomography continues to grow despite evidence on known risks of computed tomography-related radiation and induction of fatal cancers in children. More than 60 million computed tomography scans are estimated to be performed annually in the USA, with 7 million in children. Pediatric radiologists apply the practice of ALARA ('as low as reasonably achievable') to reduce radiation exposure. Education and advocacy directed to the referring clinician reinforce these principles. Radiation exposure may be further reduced by developing clinical pathways limiting computed tomography scanning and encourage alternate, nonradiation imaging modalities, such as ultrasound and magnetic resonance imaging. Although individual risk estimates are small, widespread use of computed tomography in the population may implicate a future public health issue.

SUMMARY

Advocacy by pediatric healthcare providers to promote intelligent dose reduction based on the principles of ALARA and the judicious use of computed tomography scanning is essential to foster the safest possible care of children.

CT radiation dose in children: a survey to establish age-based diagnostic reference levels in Switzerland

This work aimed at assessing the doses delivered in Switzerland to paediatric patients during computed tomography (CT) examinations of the brain, chest and abdomen, and at establishing diagnostic reference levels (DRLs) for various age groups. Forms were sent to the ten centres performing CT on children, addressing the demographics, the indication and the scanning parameters: number of series, kilovoltage, tube current, rotation time, reconstruction slice thickness and pitch, volume CT dose index (CTDI(vol)) and dose length product (DLP). Per age group, the proposed DRLs for brain, chest and abdomen are, respectively, in terms of CTDI(vol): 20, 30, 40, 60 mGy; 5, 8, 10, 12 mGy; 7, 9, 13, 16 mGy; and in terms of DLP: 270, 420, 560, 1,000 mGy cm; 110, 200, 220, 460 mGy cm; 130, 300, 380, 500 mGy cm. An optimisation process should be initiated to reduce the spread in dose recorded in this study. A major element of this process should be the use of DRLs.

Cumulative diagnostic radiation exposure in children with ventriculoperitoneal shunts: a review

INTRODUCTION

Children may be more vulnerable to diagnostic radiation exposure because of the increased dose-volume ratio and the increased lifetime risk per unit dose of radiation from early exposure. Moreover, recent radiological literature suggests that exposure to ionizing radiation from imaging studies may play a role in the later development of malignancies.

MATERIALS AND METHODS

We review the literature and present two illustrative clinical examples of children (each child developed head and neck malignancies during their late teen years) with hydrocephalus requiring multiple cerebrospinal fluid (CSF) shunt revisions and diagnostic computerized tomography (CT) scans throughout their life.

DISCUSSION

The literature reviewed suggests that children are more prone to diagnostic radiation exposure. Although it is not possible to prove that the multiple diagnostic studies result in malignancies, our review of the literature and illustrative cases describing malignancy risk and radiation exposure should give clinicians pause when considering requesting multiple diagnostic CT studies in children during the evaluation of possible CSF shunt dysfunction. Alternative tests such as "shunt MRI" protocols should be considered for patients and used whenever possible to minimize exposure to ionizing radiation.

Paediatric CT: the effects of increasing image noise on pulmonary nodule detection

BACKGROUND

A radiation dose of any magnitude can produce a detrimental effect manifesting as an increased risk of cancer. Cancer development may be delayed for many years following radiation exposure. Minimizing radiation dose in children is particularly important. However, reducing the dose can reduce image quality and may, therefore, hinder lesion detection.

OBJECTIVE

We investigated the effects of reducing the image signal-to-noise ratio (SNR) on CT lung nodule detection for a range of nodule sizes.

MATERIALS AND METHODS

A simulated nodule was placed at the periphery of the lung on an axial CT slice using image editing software. Multiple copies of the manipulated image were saved with various levels of superimposed noise. The image creation process was repeated for a range of nodule sizes. For a given nodule size, output images were read independently by four Fellows of The Royal College of Radiologists.

RESULTS

The overall sensitivities in detecting nodules for the SNR ranges 0.8-0.99, 1-1.49, and 1.5-2.35 were 40.5%, 77.3% and 90.3%, respectively, and the specificities were 47.9%, 73.3% and 75%, respectively. The sensitivity for detecting lung nodules increased with nodule size and increasing SNR. There was 100% sensitivity for the detection of nodules of 4-10 mm in diameter at SNRs greater than 1.5.

CONCLUSION

Reducing medical radiation doses in children is of paramount importance. For chest CT examinations this may be counterbalanced by reduced sensitivity and specificity combined with an increased uncertainty of pulmonary nodule detection. This study demonstrates that pulmonary nodules of 4 mm and greater in diameter can be detected with 100% sensitivity provided that the perceived image SNR is greater than 1.5.

The radiation burden of radiological investigations

The harmful effects of ionising radiation are widely acknowledged. It has been reported that young children, particularly girls, have a higher sensitivity to radiation than adults. However, the exact detrimental effects of radiation, particularly at the low doses used in routine diagnostic radiography, are unknown and the subject of much controversy. Computed tomography (CT) accounts for about 9% of all radiological examinations but is responsible for 47% of medical radiation dose. Approximately 11% of CT examinations performed are in the paediatric population, but the long-term hazards of CT are unknown.

Radiation doses to children with shunt-treated hydrocephalus

BACKGROUND

Children with shunt-treated hydrocephalus are still followed routinely with frequent head CT scans.

OBJECTIVE

To estimate the effective dose, brain and lens doses from these examinations during childhood, and to assess dose variation per examination.

MATERIALS AND METHODS

All children born between 1983 and 1995 and treated for hydrocephalus between 1983 and 2002 were included. We retrospectively registered the number of examinations and the applied scan parameters. The effective dose was calculated using mean conversion factors from the CT dose index measured free in air, while doses to the lens and brain were estimated using tabulated CT dose index values measured in a head phantom.

RESULTS

A total of 687 CT examinations were performed in 67 children. The mean effective dose, lens dose and brain dose to children over 6 months of age were 1.2 mSv, 52 mGy and 33 mGy, respectively, and the corresponding doses to younger children were 3.2 mSv, 60 mGy and 48 mGy. The effective dose per CT examination varied by a factor of 64.

CONCLUSION

None of the children was exposed to doses known to cause deterministic effects. However, since the threshold for radiation-induced damage is not known with certainty, alternative modalities such as US and MRI should be used whenever possible.

PET/CT and SPECT/CT dosimetry in children: the challenge to the pediatric imager

Both positron emission tomography (PET) and computed tomography (CT) contribute significantly to the effective dose from PET/CT imaging. For PET imaging, the effective dose is related to the administered activity and age of patient. For CT, there are many factors that determine effective dose. Effective dose is dependent on tube current (mA), tube potential (kVp), rotation speed, pitch, slice thickness, patient mass, and the exact volume of the patient that is being imaged. The CT scan may be acquired at exposure parameters similar to those used for diagnostic CT, but more commonly, the tube current is reduced and a localization CT scan of somewhat less than optimal diagnostic quality is obtained. A very low dose CT scan for attenuation correction may also be considered.

Informing parents about CT radiation exposure in children: it's OK to tell them

OBJECTIVE

The purpose of our study was to determine how parents' understanding of and willingness to allow their children to undergo CT change after receiving information regarding radiation dose and risk.

MATERIALS AND METHODS

One hundred parents of children undergoing nonemergent CT studies at a tertiary-care children's hospital were surveyed before and after reading an informational handout describing radiation risk. Parental knowledge of whether CT uses radiation or increases lifetime risk of cancer was assessed, as was willingness to permit their child to undergo both a CT examination that their child's doctor recommended and one for which their doctor thought observation might be equally effective.

RESULTS

Of the 100 parents who were surveyed, 66% believed CT uses radiation before reading the handout, versus 99% afterward (p < 0.01). Before reading the handout, 13% believed CT increases the lifetime risk of cancer, versus 86% afterward (p < 0.01). After reading the handout, parents became less willing to have their child undergo CT given a hypothetic situation in which their doctor believed that either CT or observation would be equally effective (p < 0.01), but their willingness to have their child undergo CT recommended by their doctor did not significantly change. After reading the handout, 62% of parents reported no change in level of concern. No parent refused or requested to defer CT after reading the handout.

CONCLUSION

A brief informational handout can improve parental understanding of the potential increased risk of cancer related to pediatric CT without causing parents to refuse studies recommended by the referring physician.

Radiation risk to children from computed tomography

Imaging studies that use ionizing radiation are an essential tool for the evaluation of many disorders of childhood. Ionizing radiation is used in radiography, fluoroscopy, angiography, and computed tomography scanning. Computed tomography is of particular interest because of its relatively high radiation dose and wide use. Consensus statements on radiation risk suggest that it is reasonable to act on the assumption that low-level radiation may have a small risk of causing cancer. The medical community should seek ways to decrease radiation exposure by using radiation doses as low as reasonably achievable and by performing these studies only when necessary. There is wide agreement that the benefits of an indicated computed tomography scan far outweigh the risks. Pediatric health care professionals' roles in the use of computed tomography on children include deciding when a computed tomography scan is necessary and discussing the risk with patients and families. Radiologists should be a source of consultation when forming imaging strategies and should create specific protocols with scanning techniques optimized for pediatric patients. Families and patients should be encouraged to ask questions about the risks and benefits of computed tomography scanning. The information in this report is provided to aid in decision-making and discussions with the health care team, patients, and families.

Computed tomography and radiation: understanding the issues

We are currently seeing increasing opportunities to improve patient care with computed tomography (CT). At the same time, we are challenged to use this technology wisely. In particular, we are being asked to balance the benefits against the risks, chiefly those of ionizing radiation. To do this, we must have a foundation from which to determine the relative risks. This foundation necessarily must be composed of several components. First, it is important to understand the patterns of use and increasing application of CT, particularly multidetector CT. In addition, it is helpful to be familiar with measures of radiation pertinent to CT and the doses provided by this modality. This foundation then provides a context in which to discuss the issue of low-dose radiation and cancer risk as well as potential changes in CT practice guidelines and regulation. It is with an understanding of these issues that radiologists and other radiology personnel can participate in an informed discussion with referring physicians and patients and continue to optimize the practice of CT.

Comparative evaluation of organ and effective doses for paediatric patients with those for adults in chest and abdominal CT examinations

Patient doses in paediatric and adult CT examinations were investigated for modern multislice CT scanners by using specially constructed in-phantom dose measuring systems. The systems were composed of 32 photodiode dosemeters embedded in various tissue and organ sites within anthropomorphic phantoms representing the bodies of 6-year-old children and adults. Organ and the effective doses were evaluated from dose values measured at these sites. In chest CT examinations, organ doses for organs within the scanning area were 2-21 mGy for children and 7-26 mGy for adults. Thyroid doses for children were frequently the highest with a maximum of 21 mGy. In abdominal CT examinations, organ doses for organs within the scanning area were 3-16 mGy for children and 10-34 mGy for adults. Effective doses evaluated for children and adults were found to be proportional to the effective mAs of CT scanners, where linear coefficients were specific to the types of CT examinations and to the manufacturers of CT scanners. Effective doses in paediatric chest CT and abdominal CT examinations were lower than those in adult examinations by a factor of two or greater on average for the same CT scanners because of the lower effective mAs adopted in paediatric examinations.

MDCT of Tracheobronchial Narrowing in Pediatric Patients

Chest radiographs have been useful for the incidental detection and initial imaging evaluation of clinically suspected central airway narrowing in pediatric patients. However, cross-sectional imaging, such as computed tomography (CT), is frequently required for confirmation of diagnosis, further characterization, and preoperative evaluation of surgical lesions. Recent rapid technologic advancement in CT has allowed CT to assume a pivotal role in the noninvasive evaluation of tracheobronchial narrowing in children, in particular with multidetector computed tomography with postprocessing techniques, including multiplanar reformations and 3-dimensional reconstructions. In this article, the authors review the multidetector computed tomography technique for evaluation of central airway narrowing in children, with emphasis on the use of multiplanar reformations and 3-dimensional reconstructions in the imaging evaluation of the spectrum of intrinsic and extrinsic causes of central airway narrowing in children.

Contrast-enhanced MR angiography of the chest and abdomen with use of controlled apnea in children

PURPOSE

To retrospectively determine if controlled apnea improves the image quality of contrast material--enhanced magnetic resonance (MR) angiography of the chest and abdomen in children.

MATERIALS AND METHODS

Institutional review board approval and waiver of informed consent were obtained for this HIPAA-compliant study. The authors evaluated contrast-enhanced MR angiographic procedures performed in the chest, abdomen, or both, in 23 children (14 boys, nine girls; age range, 1 month to 8 years) who were under general anesthesia. All patients underwent mechanical ventilation with preoxygenation (100% oxygen) prior to controlled apnea during image acquisition. In control subjects, the authors assessed contrast-enhanced MR angiographic procedures performed in the chest, abdomen, or both, in 23 children (matched for age and type of study with children in the controlled apnea group; 11 boys, 12 girls; age range, 1 month to 8 years) who were under general anesthesia (n=15) or deep sedation (n=8) and were breathing spontaneously during image acquisition. MR angiograms of the chest, abdomen, or both, were assessed for image quality, motion artifacts, and vessel definition by two radiologists working in consensus with a subjective grading scale. Wilcoxon signed rank test was used to assess differences in measurements.

RESULTS

Image quality was rated excellent in 97% (30 of 31) of studies with controlled apnea and in 30% (nine of 31) of control studies (P<.001). Motion artifacts were absent in 97% (30 of 31) of studies with controlled apnea and 13% (four of 31) of control studies (P<.001). Vessel sharpness was rated as being significantly better on images obtained with controlled apnea (P<.05). There were no complications caused by anesthesia or sedation in either group.

CONCLUSION

Controlled apnea is highly effective in children for eliminating respiratory motion artifacts with contrast-enhanced MR angiographic studies, resulting in greatly improved image quality and spatial resolution.

Peer assessment of pediatric surgeons for potential risks of radiation exposure from computed tomography scans

PURPOSE

Radiology literature reports potential cancer risk from radiation exposure from computed tomography (CT). We hypothesized that pediatric surgeons' knowledge of potential risks of radiation exposure from CT scan is limited.

METHODS

We used an anonymous, Internet-based peer assessment survey for members of the American Pediatric Surgical Association (APSA). The survey assessed surgeon's knowledge based on potential risks of radiation exposure from CT as well as current practice patterns for use of CT. The chi2 test of significance was used to detect any differences in responses based on years in training.

RESULTS

Twenty percent (147/753) of the American Pediatric Surgical Association members completed the survey. About one half (54%) of surgeons believe that the lifetime risk of cancer was increased because of radiation from one abdominal/pelvic CT scan, although more than 75% of respondents underestimated the radiation dose from a CT scan compared to a chest radiograph. Most surgeons generally did not discuss the potential risks of CT scan with their patients. Surgeons demonstrated a range of responses for use of CT for select clinical scenarios.

CONCLUSIONS

Pediatric surgeon's knowledge of potential risks of radiation exposure from CT scan is limited. As the radiology literature indicates an increasing awareness for potential cancer risks from radiation exposure from CT, there is also a need for education of subspecialties outside of radiology.

The use of repeated head computed tomography in pediatric blunt head trauma: factors predicting new and worsening brain injury

OBJECTIVE

Opinion is divided on the value of repeat head computed tomography for guiding clinical management of pediatric patients with blunt head trauma. This study describes the prevalence of worsening brain injury on repeat computed tomography, predictors of worsening computed tomography findings, and the frequency of neurosurgical intervention after the repeat computed tomography.

DESIGN

Retrospective cohort study.

SETTING

All patients were admitted to a level I pediatric trauma center between 1994 and 2003.

PATIENTS

Children <15 yrs old with two or more head computed tomographies following hospital admission for blunt head trauma.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We reviewed the imaging reports to determine injury progression. Potential predictors of worsening computed tomography findings and neurosurgical intervention were recorded by chart review. Logistic regression and recursive partitioning were used to identify predictors. Twenty percent (50 of 257) of patients with mild head injury had worsening computed tomography findings, and three patients (1%) had subsequent neurosurgical intervention. Patients with moderate and severe head injuries were more likely to have worsening computed tomography findings (107 of 248; 43%) and to have neurosurgical intervention (15 of 248; 6%). In most surgical patients, repeat computed tomography was preceded by rapid decline in neurologic status or elevated intracranial pressure. Stratification based on four clinical factors (initial head injury severity, any intraparenchymal finding on initial computed tomography, normal findings on initial computed tomography, coagulopathy) identified 100% of the surgical patients and 89% of patients with worsening brain injuries on the repeat computed tomography.

CONCLUSIONS

Repeat head computed tomography imaging is frequently used. About 30% of repeated computed tomographies showed new or worsening brain injury. However, worsening brain injury on repeat computed tomography rarely resulted in neurosurgical intervention. Patients with moderate or severe head injury and intraparenchymal injuries were more likely to show worsening brain injury and undergo neurosurgical intervention.

Pediatric Cardiac-Gated CT Angiography: Assessment of Radiation Dose

OBJECTIVE

The purpose of our study was to determine a dose range for cardiac-gated CT angiography (CTA) in children.

MATERIALS AND METHODS

ECG-gated cardiac CTA simulating scanning of the heart was performed on an anthropomorphic phantom of a 5-year-old child on a 16-MDCT scanner using variable parameters (small field of view; 16 x 0.625 mm configuration; 0.5-second gantry cycle time; 0.275 pitch; 120 kVp at 110, 220, and 330 mA; and 80 kVp at 385 mA). Metal oxide semiconductor field effect transistor (MOSFET) technology measured 20 organ doses. Effective dose calculated using the dose-length product (DLP) was compared with effective dose determined from measured absorbed organ doses.

RESULTS

Highest organ doses included breast (3.5-12.6 cGy), lung (3.3-12.1 cGy), and bone marrow (1.7-7.6 cGy). The 80 kVp/385 mA examination produced lower radiation doses to all organs than the 120 kVp/220 mA examination. MOSFET effective doses (+/- SD) were as follows: 110 mA: 7.4 mSv (+/- 0.6 mSv), 220 mA: 17.2 mSv (+/- 0.3 mSv), 330 mA: 25.7 mSv (+/- 0.3 mSv), 80 kVp/385 mA: 10.6 mSv (+/- 0.2 mSv). DLP effective doses for diagnostic runs were as follows: 110 mA: 8.7 mSv, 220 mA: 19 mSv, 330 mA: 28 mSv, 80 kVp/385 mA: 12 mSv. DLP effective doses exceeded MOSFET effective doses by 9.7-17.2%.

CONCLUSION

Radiation doses for a 5-year-old during cardiac-gated CTA vary greatly depending on parameters. Organ doses can be high; the effective dose may reach 28.4 mSv. Further work, including determination of size-appropriate mA and image quality, is important before routine use of this technique in children.

Imaging strategies to reduce the risk of radiation in CT studies, including selective substitution with MRI

"When one admits that nothing is certain one must, I think, also admit that some things are much more nearly certain than others." Bertrand Russell (1872-1970) Computed tomography (CT) is one of the largest contributors to man-made radiation doses in medical populations. CT currently accounts for over 60 million examinations in the United States, and its use continues to grow rapidly. The principal concern regarding radiation exposure is that the subject may develop malignancies. For this systematic review we searched journal publications in MEDLINE (1966-2006) using the terms "CT," "ionizing radiation," "cancer risks," "MRI," and "patient safety." We also searched major reports issued from governmental U.S. and world health-related agencies. Many studies have shown that organ doses associated with routine diagnostic CT scans are similar to the low-dose range of radiation received by atomic-bomb survivors. The FDA estimates that a CT examination with an effective dose of 10 mSv may be associated with an increased chance of developing fatal cancer for approximately one patient in 2000, whereas the BEIR VII lifetime risk model predicts that with the same low-dose radiation, approximately one individual in 1000 will develop cancer. There are uncertainties in the current radiation risk estimates, especially at the lower dose levels encountered in CT. To address what should be done to ensure patient safety, in this review we discuss the "as low as reasonably achievable" (ALARA) principle, and the use of MRI as an alternative to CT.

Automatic exposure control in multichannel CT with tube current modulation to achieve a constant level of image noise: Experimental assessment on pediatric phantoms

Automatic exposure control (AEC) systems have been developed by computed tomography (CT) manufacturers to improve the consistency of image quality among patients and to control the absorbed dose. Since a multichannel helical CT scan may easily increase individual radiation doses, this technical improvement is of special interest in children who are particularly sensitive to ionizing radiation, but little information is currently available regarding the precise performance of these systems on small patients. Our objective was to assess an AEC system on pediatric dose phantoms by studying the impact of phantom transmission and acquisition parameters on tube current modulation, on the resulting absorbed dose and on image quality. We used a four-channel CT scan working with a patient-size and z-axis-based AEC system designed to achieve a constant noise within the reconstructed images by automatically adjusting the tube current during acquisition. The study was performed with six cylindrical poly(methylmethacrylate) (PMMA) phantoms of variable diameters (10-32 cm) and one 5 years of age equivalent pediatric anthropomorphic phantom. After a single scan projection radiograph (SPR), helical acquisitions were performed and images were reconstructed with a standard convolution kernel. Tube current modulation was studied with variable SPR settings (tube angle, mA, kVp) and helical parameters (6-20 HU noise indices, 80-140 kVp tube potential, 0.8-4 s. tube rotation time, 5-20 mm x-ray beam thickness, 0.75-1.5 pitch, 1.25-10 mm image thickness, variable acquisition, and reconstruction fields of view). CT dose indices (CTDIvol) were measured, and the image quality criterion used was the standard deviation of the CT number measured in reconstructed images of PMMA material. Observed tube current levels were compared to the expected values from Brooks and Di Chiro's [R.A. Brooks and G.D. Chiro, Med. Phys. 3, 237-240 (1976)] model and calculated values (product of a reference value multiplied by a dose ratio measured with thermoluminescent dosimeters). Our study demonstrates that this AEC system accurately modulates the tube current according to phantom size and transmission to achieve a stable image noise. The system accurately controls the tube current when changing tube rotation time, tube potential, or image thickness, with minimal variations of the resulting noise. Nevertheless, CT users should be aware of possible changes of tube current and resulting dose and quality according to several parameters: the tube angle and tube potential used for SPR, the x-ray beam thickness (tube current decreases and image noise increases when doubling x-ray beam thickness), the pitch value (a pitch decrease leads to a higher dose but also to a higher noise), and the acquisition field of view (FOV) (tube current is lower when using the small acquisition FOV compared to the large one, but the use of small acquisition FOV at 120 kVp leads to a peculiar increase of tube current and CTDIvol).

Congenital scoliosis: a review and update

Vertebral anomalies causing congenital scoliosis are classified on the basis of failures of formation, segmentation, or both. The natural history depends on the type of anomaly and the location of anomaly. Patient evaluation focuses on the history and physical examination, followed by appropriate imaging modalities. The hallmark of surgical treatment is early intervention before the development of large curvatures. The surgical treatment of a congenital deformity mandates the use of neurological monitoring to minimize the risk of perioperative neurological deficit. Modern surgical techniques have evolved to include the routine use of spinal instrumentation. Patients with associated chest wall deformities or large compensatory curves may be candidates for vertical expansion prosthetic titanium rib placement or growing rods insertion to maximize growth.

Pediatric CT scan usage in Japan: results of a hospital survey

PURPOSE

The aim of this study was to examine the usage parameters of diagnostic computed tomography (CT) in children because of concerns of possible overuse in Japanese hospitals, including the "technical" CT exposure settings and the "clinical" grounds for CT requests.

MATERIALS AND METHODS

We examined the methodology at the radiology department to reduce radiation exposure to children and performed a retrospective study on pediatric CT requests during a 1-year period at Nagasaki University Hospital. The parameters of diagnostic CT usage for minor head trauma and acute appendicitis were studied in detail.

RESULTS

CT radiation dose settings are adjusted for children based on guidelines issued by the Japan Radiological Society, with few limitations. CT requests were made for 62% of minor head trauma cases and 76% of cases clinically suspected to be acute appendicitis. These figures are considerably higher than those reported by studies in the United Kingdom, Canada, or the United States. No specific guidelines are advocated regarding CT usage for minor head trauma. The diagnosis of acute appendicitis in children is almost routinely referred for "confirmation" by CT.

CONCLUSION

CT radiation risks to children at Japanese hospitals need to be considered more seriously. Physicians should be encouraged to follow diagnostic algorithms that help avoid unnecessary CT usage in children.

Suspected Appendicitis in Children: Rectal and Intravenous Contrast-enhanced versus Intravenous Contrast-enhanced CT

PURPOSE

To retrospectively compare the diagnostic performance of intravenous contrast material-enhanced computed tomography (CT) with that of intravenous and rectal contrast-enhanced CT in the evaluation of children suspected of having appendicitis by using pathologic findings, surgical findings, or a follow-up telephone call as the reference standard.

MATERIALS AND METHODS

This HIPAA-compliant study was approved by the committee on clinical investigations. As part of a larger study, informed consent was obtained from all parents and from all children older than 7 years. Consecutive patients aged 5-21 years who presented to the emergency department and were suspected of having appendicitis were studied with CT. From April 2003 until February 2004, patients underwent intravenous and rectal contrast-enhanced CT. From March 2004 until December 2004, patients underwent intravenous contrast-enhanced CT. Demographic data, clinical outcomes, and test performance characteristics--including sensitivity, specificity, accuracy, and negative and positive predictive values--were compared.

RESULTS

Of the 416 patients who met inclusion criteria, 223 underwent intravenous and rectal contrast-enhanced CT and 193 underwent intravenous contrast-enhanced CT. There were no differences in sex distribution (55% vs 52% male patients), frequency of appendicitis (36% vs 32%), or frequency of equivocal CT findings (4%) between the groups. Intravenous and rectal contrast-enhanced CT had a sensitivity of 92% (95% confidence interval [CI]: 85%, 97%), a specificity of 87% (95% CI: 79%, 92%), a negative predictive value of 94% (95% CI: 90%, 98%), and an accuracy of 89% (95% CI: 85%, 93%). Intravenous contrast-enhanced CT had a sensitivity of 93% (95% CI: 84%, 97%), a specificity of 92% (95% CI: 85%, 96%), a negative predictive value of 95% (95% CI: 90%, 99%), and an accuracy of 92% (95% CI: 88%, 96%) (P > .2 for all comparisons).

CONCLUSION

There was no significant difference between the performance of intravenous contrast-enhanced CT and that of rectal and intravenous contrast-enhanced CT in children suspected of having appendicitis.

Review of radiation risks from computed tomography: essentials for the pediatric surgeon

BACKGROUND/PURPOSE

Over the past several years, increasing attention has been focused on the potential for radiation exposure from computed tomography (CT) for inducing the development of cancers. An understanding of these issues is important for the practice of pediatric surgery.

METHODS

Medline based clinical review of current medical literature of the risks for the induction of cancers by CT. Data includes estimates of cancer risk from computer models, epidemiologic data from survivors of atomic bomb radiation exposure, and consensus opinions from expert panels.

RESULTS

Review of scientific evidence demonstrates varied opinions, but consensus suggests there may be a potential for an increased risk of cancer from low level radiation exposure such as from CT. These calculations suggest that there may be as high as 1 fatal cancer for every 1000 CT scans performed in a young child.

CONCLUSIONS

Pediatric surgeons should be aware of the potential risks of CT. Minimizing the radiation risks of CT is a complex endeavor, and will require investments from pediatric surgeons as well as pediatric radiologists.

16-slice CT: achievable effective doses of common protocols in comparison with recent CT dose surveys

The aim of the study was to investigate achievable dose levels in 16-slice CT by evaluating CT dose indices (CTDI) and effective doses of dose-optimized protocols compared with 4-slice dose surveys. Normalized CTDI free in air and in 16 cm and 32 cm diameter phantoms were measured on four different 16-slice CT scanners in the Netherlands. All collimation and tube potential settings were analysed. Volume CTDI was calculated for adult protocols for brain, chest, pulmonary angiography (CTPA), abdomen and biphasic liver CT. Effective doses were calculated first using volume CTDI with conversion factors and second from CTDIair values using the ImPACT dose calculator. Average results of the 16-slice scanners were correlated to results of dose surveys with predominantly 4-slice scanners. Statistical analysis was done with Student t-tests with a Bonferroni correction; therefore p < 0.017 was significant. The results of CTDIair and weighted CTDI were documented for all scanners. Effective doses averaged over four scanners for brain, chest, CTPA, abdomen and biphasic liver protocols were 1.9+/-0.4, 3.8+/-0.4, 3.0+/-0.2, 7.2+/-0.9 and 10.2+/-1.3 mSv, respectively. Compared with dose surveys achievable effective doses were equal (p = 0.069) to significantly lower (p < 0.017) for chest and abdomen protocols. For 16-slice spiral brain CT there was a trend of equal doses compared with sequential brain CT in the dose surveys. Thus, with dose-optimized protocols 16-slice CT can achieve equal to lower effective doses in examinations of the chest and abdomen compared with 4-slice CT, while doses can remain stable in the brain.

Dose reduction in paediatric MDCT: general principles

The number of multi-detector array computed tomography (MDCT) examinations performed per annum continues to increase in both the adult and paediatric populations. Estimates from 2003 suggested that CT contributed 17% of a radiology department's workload, yet was responsible for up to 75% of the collective population dose from medical radiation. The effective doses for some CT examinations today overlap with those argued to have an increased risk of cancer. This is especially pertinent for paediatric CT, as children are more radiosensitive than adults (and girls more radiosensitive than boys). In addition, children have a longer life ahead of them, in which radiation induced cancers may become manifest. Radiologists must be aware of these facts and practise the ALARA (as low as is reasonably achievable) principle, when it comes to deciding CT protocols and parameters.

Portal imaging practice patterns of children's oncology group institutions: Dosimetric assessment and recommendations for minimizing unnecessary exposure

PURPOSE

To determine and analyze the dosimetric consequences of current portal imaging practices for pediatric patients, and make specific recommendations for reducing exposure from portal imaging procedures.

METHODS AND MATERIALS

A survey was sent to approximately 250 Children's Oncology Group (COG) member institutions asking a series of questions about their portal imaging practices. Three case studies are presented with dosimetric analysis to illustrate the magnitude of unintended dose received by nontarget tissues using the most common techniques from the survey.

RESULTS

The vast majority of centers use double-exposure portal image techniques with a variety of open field margins. Only 17% of portal images were obtained during treatment, and for other imaging methods, few centers subtract monitor units from the treatment delivery. The number of monitor units used was nearly the same regardless of imager type, including electronic portal imaging devices. Eighty-six percent imaged all fields the first week and 17% imaged all fields every week. An additional 1,112 cm3 of nontarget tissue received 1 Gy in one of the example cases. Eight new recommendations are made, which will lower nontarget radiation doses with minimal impact on treatment verification accuracy.

CONCLUSION

Based on the survey, changes can be made in portal imaging practices that will lower nontarget doses. It is anticipated that treatment verification accuracy will be minimally affected. Specific recommendations made to decrease the imaging dose and help lower the rate of radiation-induced secondary cancers in children are proposed for inclusion in future COG protocols using radiation therapy.

Patient Radiation Doses from Adult and Pediatric CT

OBJECTIVE

The purpose of our study was to determine typical organ doses, and the corresponding effective doses, to adult and pediatric patients undergoing a single CT examination.

MATERIALS AND METHODS

Heads, chests, and abdomens of patients ranging from neonates to oversized adults (120 kg) were modeled as uniform cylinders of water. Monte Carlo dosimetry data were used to obtain average doses in the directly irradiated region. Dosimetry data were used to compute the total energy imparted, which was converted into the corresponding effective dose using patient-size-dependent effective-dose-per-unit-energy-imparted coefficients. Representative patient doses were obtained for scanning protocols that take into account the size of the patient being scanned by typical MDCT scanners.

RESULTS

Relative to CT scanners from the early 1990s, present-day MDCT scanners result in doses that are approximately 1.5 and approximately 1.7 higher per unit mAs in head and body phantoms, respectively. Organ absorbed doses in head CT scans increase from approximately 30 mGy in newborns to approximately 40 mGy in adults. Patients weighing less than approximately 20 kg receive body organ absorbed doses of approximately 7 mGy, which is a factor of 2 less than for normal-sized (70-kg) adults. Adult head CT effective doses are approximately 0.9 mSv, four times less than those for the neonate. Effective doses for neonates undergoing body CT are approximately 2.5 mSv, whereas those for normal-sized adults are approximately 3.5 mSv.

CONCLUSION

Representative organ absorbed doses in CT are substantially lower than threshold doses for the induction of deterministic effects, and effective doses are comparable to annual doses from natural background radiation.

Pediatric ophthalmic computed tomographic scanning and associated cancer risk

PURPOSE

To review pediatric neuroimaging studies of the head and orbit and the radiation-induced cancer risk associated with computed tomography in light of recent attention to pediatric radioimaging by the US Food and Drug Administration, the National Cancer Institute, pediatricians, and radiologists.

DESIGN

Perspective.

METHODS

Literature review.

SETTING

Institutional.

PATIENT POPULATION

Pediatric ophthalmic patients requiring neuroimaging studies. INTERVENTION/PROCEDURE: Review of the current literature.

MAIN OUTCOME MEASURES

After review of the current literature and discussion of the related issues, recommendations are made for pediatric neuroimaging studies of the head and orbit.

RESULTS

Computed tomography (CT) of the head and orbit may be performed in children with the appropriate indications as long as the radiation exposure is minimized.

CONCLUSIONS

Information obtained from CT scans of the head and orbit may determine or affect management in the pediatric ophthalmic population. Because of the concern of cancer induced by radiation exposure in children, neuroimaging modalities without radiation exposure, such as magnetic resonance imaging or ultrasound, may be considered. However, when CT is indicated, it is reasonable and acceptable to perform CT of the head and orbit while minimizing the radiation exposure, thereby adhering to the "ALARA" (as low as reasonably achievable) policy recommended by the US Food and Drug Administration. Further studies of the actual radiation dose delivered during pediatric CT of the head and orbit and the true incidence of radiation-induced cancers after scans are warranted.

Utility of serial computed tomography imaging in pediatric patients with head trauma

OBJECT

The purpose of this study was to evaluate the risk of progression of traumatic intracranial lesions in children by comparing initial and subsequent computed tomography (CT) scans. Reserving repeated CT imaging for patients who harbor higher-risk lesions may reduce overall radiation exposure, the need for sedative agents, and cost.

METHODS

The authors performed a retrospective cohort study in 268 patients younger than 18 years of age who underwent repeated CT scanning within 24 hours of their initial CT scanning procedure. The risk of progression between the initial and repeated CT scanning sessions and the need for delayed neurosurgical intervention were determined for each lesion type. In 54 patients (20.1%) the normal findings on the initial CT study did not change on subsequent imaging. In 61 (28.5%) of the 214 patients in whom abnormal findings were present on the initial scan, progression was demonstrated. Patients with epidural hematoma (EDH; odds ratio [OR] 12.29), subdural hematoma (SDH; OR 3.18), cerebral edema (OR 9.34), and intraparenchymal hemorrhage (IPH; OR 18.3) were found to be at a significantly increased risk for progression and to require delayed neurosurgical intervention (OR 11.91). No significantly increased risk was found for patients with subarachnoid hemorrhage (SAH), intraventricular hemorrhage (IVH), diffuse axonal injury (DAI), or skull fracture.

CONCLUSIONS

Repeated CT imaging in children with high-risk lesions such as EDH, SDH, cerebral edema, and IPH is recommended. However, in children with low-risk lesions, such as SAH, IVH, DAI, and isolated skull fractures but no sign of clinical deterioration, repeated imaging may be less likely to alter the clinical management scheme. The limited benefits of undertaking repeated imaging in these patients should be weighed against the risks of radiation exposure, sedation, intrahospital transportation, and patient monitoring.

Conventional and CT angiography in children: dosimetry and dose comparisons

Tremendous advances have been made in imaging in children with both congenital and acquired heart disease. These include technical advances in cardiac catheterization and conventional angiography, especially with advancements in interventional procedures, as well as noninvasive imaging with MR and CT angiography. With rapid advances in multidetector CT (MDCT) technology, most recently 64-detector array systems (64-slice MDCT), have come a number of advantages over MR. However, both conventional and CT angiography impart radiation dose to children. Although the presence of radiation exposure to children has long been recognized, it is apparent that our ability to assess this dose, particularly in light of the rapid advancements, has been limited. Traditional methods of dosimetry for both conventional and CT angiography are somewhat cumbersome or involve a potential for substantial uncertainty. Recent developments in dosimetry, including metal oxide semiconductor field effect transistors (MOSFET) and the availability of anthropomorphic, tissue-equivalent phantoms have provided new opportunities for dosimetric assessments. Recent work with this technology in state-of-the-art cardiac angiography suites as well as with MDCT have offered direct comparisons of doses in infants and children undergoing diagnostic cardiac evaluation. It is with these dose data that assessment of risks, and ultimately the assessment of risk-benefit, can be better achieved.

Assessment of radiation dose awareness among pediatricians

BACKGROUND

There is increasing awareness among pediatric radiologists of the potential risks associated with ionizing radiation in medical imaging. However, it is not known whether there has been a corresponding increase in awareness among pediatricians.

OBJECTIVE

To establish the level of awareness among pediatricians of the recent publicity on radiation risks in children, knowledge of the relative doses of radiological investigations, current practice regarding parent/patient discussions, and the sources of educational input.

MATERIALS AND METHODS

Multiple-choice survey.

RESULTS

Of 220 respondents, 105 (48%) were aware of the 2001 American Journal of Roentgenology articles on pediatric CT and radiation, though only 6% were correct in their estimate of the quoted lifetime excess cancer risk associated with radiation doses equivalent to pediatric CT. A sustained or transient increase in parent questioning regarding radiation doses had been noticed by 31%. When estimating the effective doses of various pediatric radiological investigations in chest radiograph (CXR) equivalents, 87% of all responses (and 94% of CT estimates) were underestimates. Only 15% of respondents were familiar with the ALARA principle. Only 14% of pediatricians recalled any relevant formal teaching during their specialty training. The survey response rate was 40%.

CONCLUSION

Awareness of radiation protection issues among pediatricians is generally low, with widespread underestimation of relative doses and risks.

The accuracy of 3-dimensional magnetic resonance 3D vibe images of the mandible: an in vitro comparison of magnetic resonance imaging and computed tomography

OBJECTIVE

The purpose of this study was to investigate in vitro the accuracy of three-dimensional (3D) magnetic resonance imaging (MRI) to measure the mandible.

STUDY DESIGN

The optimal MRI sequence for 3D mandible from the data of 2 volunteers was determined to be 3D vibe. MRI and computed tomography (CT) scans of tube, mandible, and hemimandible phantoms were obtained. MRI with 3D vibe and standard parameters used in clinical practice for 3D reconstructions of jawbones on CT were used. Pearson's correlation coefficient, standard deviation (SD), and accuracy in measurement on reconstructed 3D MRI and CT were compared to direct osteometric measurement of the phantoms.

RESULTS

The correlation coefficient between MRI and direct osteometry was high, with r = 0.85 to 0.99 (P < .001). The difference ranged from -1.5 to 0.7 mm (-8.9%-11.1%) on smaller distances, which is important for orthognathic surgery. The accuracy of MRI was similar to that of CT.

CONCLUSION

3D vibe MRI provided adequate dimensional accuracy and image quality during in vitro examination of the mandible.

The utilization of pediatric computed tomography in a large Israeli Health Maintenance Organization

BACKGROUND

Concern has been raised about the potential risks related to radiation exposure from CT scans, particularly among children. However, to date, there are few data available describing the magnitude of pediatric CT utilization.

OBJECTIVE

The aim of the study was to explore patterns of CT use in pediatric patients, with respect to time, use of multiple scans, body regions imaged, and medical diagnoses.

MATERIALS AND METHODS

Records of 22,223 scans performed on 18,075 people aged < or =18 years over the period 1999-2003, including diagnoses recorded within 21 days after the examination, were obtained from a large Israeli Health Maintenance Organization (1,600,000 members).

RESULTS

The highest annual CT examination rate (per 1,000) was recorded in 2001 (10.1) compared to 7.0 and 6.3 in 1999 and 2003, respectively. The lowest rate (three scans per 1,000) was found for 3-year-old children, with increasing rates with age. The head was the most frequently scanned region, both in young children (78%) and adolescents (39%). Symptoms of ill-defined conditions and injuries were documented in 22% and 10% of all scans, respectively.

CONCLUSIONS

Although the results suggest that children comprise only 3% of all patients undergoing CT, this important modality must be carefully used because of their increased radiosensitivity, higher effective radiation doses, and longer life expectancy.

[Modern imaging technology for childhood urinary tract infection]

Imaging in childhood urinary tract infection (UTI) is still a matter of debate. There are established guidelines, however new knowledge and the changed medical environment have enhanced this ongoing discussion. These new insights have impacted therapy and consequently the imaging algorithm. Modern imaging methods -- particularly MRI and modern ultrasound (US) -- are less invasive with a lower radiation burden. Additionally, it has been shown that VUR is a poor predictor for renal scarring out, which affects long-term results. Furthermore, the majority of UT malformations is depicted by prenatal US. The most crucial aspect of improving long-term outcome appears to be the early and reliable depiction of UTI and effective treatment to prevent renal scarring. This review tries to present this new knowledge and to discuss the potential of modern imaging. Recent changes in imaging algorithms are highlighted and an outcome-oriented algorithm that addresses these recent developments is proposed, without lightly abandoning established standards. It consists of an orienting US and -- for depiction of renal involvement -- amplitude coded color Doppler sonography or renal static scintigraphy (considered the gold standard, particularly for evaluating scars); in future MRI may play a role. Based on this concept, only patients with renal damage as well as patients with complex urinary tract malformations or intractable recurrent UTI may have to undergo VCUG.

Paediatric and adult computed tomography practice and patient dose in Australia

The current practice for CT scanning of paediatric patients in Australia has been assessed through a survey sent to the site of all CT scanners licensed in New South Wales and all dedicated children's hospitals in Australia. The survey addressed demographic details, CT scanner details and scanning parameters for four imaging scenarios (brain CT, chest CT, abdomen/pelvis CT and high-resolution chest CT for three different age groups (8 weeks, 5-7 years and adult patients). The effective dose for each imaging scenario and age group was calculated and compared for 52 sites representing 53 CT scanners. For any age group and imaging scenario, there was a large spread of effective dose. For comparable CT examinations, the effective dose varied by up to 36-fold between centres. There was a clear trend for centres that frequently carry out CT scans on paediatric patients to have the lowest radiation doses. Four age group/imaging scenarios showed significantly lower effective doses for hospital-based CT than for nonhospital sites. There was also a trend for doses to be lower at dedicated paediatric centres. Effective dose was closely associated with mAs, with most centres using lower mAs for younger patients, but few centres reduced the kVp for paediatric patients. The results of the survey emphasize the need for continuing education and protocol review, particularly in paediatric CT examinations, in a complex and fast changing environment.

Effective radiation dose from radiologic studies in pediatric trauma patients

Evaluation of the pediatric trauma patient frequently requires radiologic studies. Although low-dose radiation from diagnostic radiology is considered safe, lifetime risks per unit dose of radiation are increased in children compared to adults. The total effective dose of radiation to a typical pediatric trauma patient is unknown. We sought to estimate the total effective dose of radiation related to the radiologic assessment of injured children admitted to a pediatric Level I trauma center. We reviewed the radiology records of all children admitted directly to a trauma center in 2002 and tabulated all plain films, computed tomograms, angiographic/fluoroscopic studies, and nuclear medicine studies. Using age-adjusted effective doses (which incorporate biologic effects of radiation), we computed each patient's total effective dose of radiation. Of 506 admitted patients, 394 (78%) underwent at least one radiologic study. The mean total effective dose per patient was 14.9 mSv (median: 7.2 mSv; interquartile range: 2.2-27.4 mSv). On average, computed tomography accounted for 97.5% of total effective dose. Age and injury severity score did not predict total effective dose. We conclude that in pediatric trauma patients, the estimated total effective dose of radiation varied widely. Computed tomography contributed virtually the entire total effective dose. Regarding radiographic evaluation of pediatric trauma patients, the risks and benefits of current practices should continue to be evaluated critically, because lifetime risks associated with radiation exposure are inversely proportional to age at exposure.

Modern pediatric ultrasound: potential applications and clinical significance. A review

After the introduction of ultrasound (US), the new imaging modality was first warmly welcomed, but then lost reputation and importance particularly in radiology leading to an increasing number of other -- particularly computed tomography (CT) -- investigations, which especially in pediatrics was a potentially dangerous development considering the radiation hazards. However, innovative and creative US approaches as well as new US techniques such as amplitude-coded color Doppler, harmonic and high-resolution imaging, and US contrast media or three-dimensional US have been introduced over the past decade and significantly broadened the potential of US. Thus, now, the role of US has been widened in many conditions and queries, and US today may well play a more pronounced and essential role in modern imaging algorithms at still relatively low cost, with sufficient diagnostic accuracy and conspicuity. Particularly in the pediatric setting, these new capabilities are applicable in many queries and almost all body regions and should be used to reduce the number of more invasive or radiating and relatively costly examinations that often additionally need some sedation or intravenous iodinated contrast material. To readily provide this approach for sick children, we need to promote the knowledge about modern US capabilities, to train US staff to guarantee 24-h availability of adequate pediatric US performance, and to make it known to the referring clinicians.

Pulmonary sarcoidosis in a 14-year-old boy diagnosed by low-dose CT-guided transthoracic lung biopsy

Pulmonary sarcoidosis is a rare disease in the pediatric age group, characterized by the presence of epitheloid-cell granulomas. In stage 3 sarcoidosis, pulmonary infiltrates without hilar lymphadenopathy occur. Definitive diagnosis requires a histopathological specimen, which might be difficult to obtain by transbronchial biopsy. Multidetector computed tomography (MDCT)-guided transthoracic lung biopsy (TLB) is a well-established procedure in adults, but has only rarely been applied in children.A 14-year-old boy was admitted to hospital for evaluation of a chronic systemic disease with severe pulmonary manifestation. All investigations, including bronchosopy and bronchoalveolar lavage with microbiological and virological testing, had been negative. MDCT-guided TLB was performed on a 16-section scanner with a low-dose protocol (single slices, 120 kV, 20 mAs), using a 16-gauge biopsy device. The total effective dose was 0.4 mSv for the biopsy procedure. Histopathological examination revealed multiple epitheloid-cell granulomas with giant cells in the absence of microbiological or virological abnormalities. A diagnosis of stage 3 pulmonary sarcoidosis was made and systemic anti-inflammatory therapy was administered, which led to complete remission within weeks. MDCT-guided TLB can be a valuable instrument in assessing pulmonary manifestations of pediatric sarcoidosis, enabling precise histopathological diagnosis and adequate therapy. The use of low-dose protocols can substantially reduce radiation exposure without relevant loss of image information. MDCT-guided lung biopsy should be considered prior to open-lung surgery in selected patients with unclear pulmonary disease.