The impact of pediatric-specific dose modulation curves on radiation dose and image quality in head computed tomography

Organ-based tube current modulation and bismuth eye shielding in pediatric head computed tomography

BACKGROUND

Exposure of the eye lens to ionizing radiation results in cataract. Several dose optimization techniques to protect the lens are available for computed tomography (CT).

OBJECTIVE

The radiation dose to the eye lens, volume CT dose index (CTDI_vol) and image quality of various methods of dose optimization were evaluated for pediatric head CT: automated tube current modulation (ATCM), automated tube voltage selection (ATVS), organ-based tube current modulation (OBTCM) and bismuth shielding.

MATERIALS AND METHODS

An anthropomorphic phantom of a 5-year-old child was scanned with nine protocols: no dose optimization technique and then adding different dose optimization techniques alone and in combination. Dose to the eye, thyroid and breast were estimated using metal oxide semiconductor field effect transistor (MOSFET) dosimetry. CTDI_vol, influence of timing of shield placement, image noise and attenuation values in 13 regions of interest of the head and subjective image quality were compared.

RESULTS

The eye shield significantly reduced the eye lens dose when used alone, to a similar degree as when using all software-based techniques together. When used in combination with software-based techniques, the shield reduced the eye lens dose by up to 45% compared to the no dose optimization technique. Noise was significantly increased by the shield, most pronounced in the anterior portion of the eye.

CONCLUSION

The combination of ATCM, ATVS, OBTCM and a bismuth shield, with the shield placed after acquiring the localizer image, should be considered to reduce the radiation dose to the eye lens in pediatric head CT.

Relation between age and CT radiation doses: Dose trends in 705 pediatric head CT

PURPOSE

To evaluate the relationship between patient age and radiation doses associated with routine pediatric head CT performed with automatic tube potential selection and tube current modulation techniques.

METHODS

We obtained patient demographics, scan parameters, and radiation dose descriptors (CT dose index volume -CTDIvol and dose length product -DLP) associated with consecutive routine head CT in 705 children (mean age 6.9 ± 5 years). Children were scanned on one of the three multidetector-row CTs (64-128 slices, Siemens) over 6 months period in a tertiary hospital. All head CT exams were performed in helical scan mode using automatic tube potential selection (Care kV) and automatic tube current modulation (Care Dose 4D) techniques. The information was obtained from a radiation dose monitoring software. Data were analyzed using linear correlation and analysis of variance.

RESULTS

Most age-wise median CTDIvol (9-27 mGy; 703/705 pediatric head CT, >99 %) from our institution were lower than the European Diagnostic Reference Levels (EDRL, CTDIvol 24-50 mGy) but median DLP (151-586 mGy cm) from 201/705 children (28 %) was higher than the EDRL (DLP 300-650 mGy cm). Unlike the age-stratified EDRL, a combination of automatic tube potential selection and tube current modulation for pediatric head results in a significant linear correlation between radiation doses and patient age (r2 = 0.66, p < 0.001).

CONCLUSIONS

Radiation doses for head CT change linearly with children's age. Despite lower CTDIvol and DLP for most children, longer scan length resulted in higher DLP for some pediatric head CT compared to the corresponding EDRL; this result underscores the need to promote clear guidelines for technologists operating CT.

Radiographer research in radiation protection: National and European perspectives

The author of this paper gives an overview about the evolution of radiography education in Portugal and reflects about the importance of Radiographer-led research, especially in the field of radiation protection and its impact in clinical practice. It also pinpoints several aspects that contribute to the visibility and recognition of the role of radiographer both at national and European level, where the importance of the European Federation of Radiographers Societies is crucial. Radiographer led research is necessary and fundamental to develop the radiography profession field ok knowledge and to provide evidence to sustain the implementation and adoption of new clinical practices. Evidence shows that Radiographer-led research in the field of Radiation Protection contributes significantly to decrease patient and staff exposure to ionizing radiation, while maintaining the quality of diagnostic and therapeutic procedures.

Virtual modeling, stereolithography, and intraoperative CT guidance for the optimization of sagittal synostosis reconstruction: a technical note

INTRODUCTION

Sagittal synostosis affects 1 in 1000 live births and may result in increased intracranial pressure, hindrance of normal neural development, and cosmetic deformity due to scaphocephaly. Historically, several approaches have been utilized for surgical correction and recently, computed tomography (CT)-guided reconstruction procedures are increasingly used. In this report, the authors describe the use of a CT-derived virtual and stereolithographic (3D printed) craniofacial models, which are used to guide intraoperative bone placement, and intraoperative CT guidance for confirmation of bone placement, to ensure the accuracy of surgical correction of scaphocephaly, as demonstrated to parents.

METHODS

Preoperative high-resolution CT imaging was used to construct 3D image sets of the skulls of two infants (a 14-month-old female and a 6-month-old male) with scaphocephaly. These 3D image sets were then used to create a virtual model of the proposed surgical correction for each of the infants' deformities, which was then printed and made available for use intraoperatively to plan the bone flap, fashion the bone cuts, and optimize graft placement. After the remodeling, adherence to the preoperative plan was assessed by overlaying a CT scan of the remodeled skull with the virtual model. Deviations from the preoperative model were noted.

RESULTS

Both patients had excellent postoperative cosmetic correction of head shape and contouring. The mean operative time was 5 h, blood loss was 100 ml, and one child required modification of the subocciput after intraoperative imaging showed a deviation of the reconstruction from the surgical goal as depicted by the preoperative model.

CONCLUSION

The addition of neuro-navigation to stereolithographic modeling ensured the accuracy of the reconstruction for our patients and provided greater confidence to both surgeons and parents. While unisutural cases are presented for clarity, correction was still required for one patient. The cost of the models and the additional CT required must be weighed against the complexity of the procedure and possibly reserved for patients with potentially complicated corrections.

The changing use of pediatric CT in Australia

BACKGROUND

Despite the medical benefits of CT, there are concerns about increased cancer risks following CT scans in childhood.

OBJECTIVE

To assess Australian temporal trends in pediatric CT scans funded through Medicare over the period 1985 to 2005, as well as changes in the types of CT scanners used.

MATERIALS AND METHODS

We studied de-identified electronic records of Medicare-funded services, including CT scans, that were available for children and adults younger than 20 years between 1985 and 2005. We assessed temporal trends using CT imaging rates by age, gender and anatomical region. Regulators provided CT scanner registration lists to identify new models installed in Australia and to date the introduction of new technologies.

RESULTS

Between 1985 and 2005, 896,306 Medicare-funded CT services were performed on 688,260 individuals younger than 20 years. The imaging rate more than doubled during that time period. There were more than 1,000 CT scanners on registration lists during the study period. There were both a sharp increase in the availability of helical scanning capabilities from 1994 and significant growth in multi-detector CT scanners from 2000.

CONCLUSION

Significant increases in the rate of pediatric CT scanning have occurred in Australia. This rate has stabilized since 2000, possibly a result of better understanding of cancer risks.