Guidelines for anti-scatter grid use in pediatric digital radiography

AWARENESS OF PAEDIATRIC RADIOLOGICAL PROTECTION AND IMAGING PARAMETERS AMONG GROUP OF SRI LANKAN RADIOGRAPHERS

The present survey evaluated the level of awareness of radiological protection concepts and imaging parameters among Sri Lankan radiographers for the first time. The data were collected using an electronic questionnaire of 22 questions on demographic data, awareness of radiation protection concepts and imaging parameters. Only 84 out of 122 (68.8%) requested radiographers to return the questionnaire. More than 85% had ≥3 years of experience in the radiography field. The average scores for questions on best practices, imaging parameters and radiation protection were 75, 75.8 and 70.2%, respectively, with an overall score of 73.4%. Significant confusion existed on protective shielding, paediatric consenting capability, use of grids and excess X-ray field during paediatric radiography. Although the overall knowledge and awareness of participants on studied concepts were satisfactory, a continuous professional development credit system and implementation of a code of practice are required to improve the quality of radiography practice.

Workload and use factor data for a modern digital radiography system

The well-referenced structural shielding design NCRP Report No. 147 uses workload information based on self-reported film-screen data from the AAPM Task Group 9 survey. The aim of this study was to assess the clinical workload distributions of modern digital radiography (DR) systems in general hospital and pediatric-only practices. A retrospective analysis of DR imaging data on four radiographic systems in a hospital practice and two radiographic systems in a pediatric practice, through a custom clinical DICOM header analytics program. A total of 203, 294 exposures from the general hospital practice and 25,415 from the pediatric practice from 2019 and 2021 were included. Values for kVp, mAs, and detector type (wall bucky, table bucky, or free detector) were extracted. For each exam, mAs was accumulated in a kVp histogram with bins 5 kVp wide and further parsed by detector type. Total workload was calculated by summing all exposures, then normalized by the number of patients. The median (25th and 75th percentile) workload in the hospital practice was 0.43 (0.22, 1.13) mA-min per patient, while the average was 1.36 ± 3.08. Pediatric data yielded a median (25th and 75th percentile) of 0.10 (0.05, 0.23) and an average of 0.29 ± 0.69 mA-min per patient. Mean number of patients per week was 230 adult and 57 pediatric. Hospital workload data is approximately 44% less than the NCRP Report No. 147 value.

CIRSE Standards of Practice on Varicocele Embolisation

BACKGROUND

Percutaneous embolisation is an effective, minimally invasive means of treating a variety of benign and malignant lesions and has been successfully used to treat varicoceles since the late 1970s, with refined and expanded techniques and tools currently offering excellent outcomes for varicocele embolisation.

PURPOSE

This document will presume that the indication for treatment is clear and approved by the multidisciplinary team (MDT) and will define the standards required for the performance of each modality, as well as their advantages and limitations. CIRSE Standards of Practice documents are not intended to impose a standard of clinical patient care, but recommend a reasonable approach to, and best practices for, the performance of percutaneous varicocele embolisation.

METHODS

The writing group was established by the CIRSE Standards of Practice Committee and consisted of five clinicians with internationally recognised expertise in embolisation of male varicoceles. The writing group reviewed the existing literature on varicocele embolisation, performing a pragmatic evidence search using PubMed to search for publications in English and relating to human subjects published from 2006 to 2021. The final recommendations were formulated through consensus.

CONCLUSION

Embolisation has an established role in the successful management of male varicoceles. This Standards of Practice document provides up-to-date recommendations for the safe performance of varicocele embolisation.

Reliability of radiographic measurements for hip dysplasia using a reduced radiation technique

The purpose of this study was to examine whether measurement accuracy is impacted with a low radiation radiograph technique. Treatment decisions for hip dysplasia require serial radiographs to monitor acetabular anatomy. However, radiation use creates concern for future malignancy. Standard radiograph technique utilizes a grid to enhance clarity, but requires a larger X-ray dose. We hypothesized grid removal would lower radiation exposure without decreasing measurement accuracy. This is a retrospective cohort study of patients with idiopathic DDH and neuromuscular hip displacement at a single institution from 2019 to 2020 receiving surveillance radiographs. A cohort receiving modified technique radiographs (grid removed) was compared to an age-matched cohort receiving standard technique radiographs. Four examiners measured radiographs on two separate occasions, a minimum of 2 weeks apart. Migration percentage (MP) was measured for neuromuscular patients and acetabular index (AI) for idiopathic DDH. Intraclass correlation coefficient (ICC) with a 95% confidence interval (CI) was used to evaluate inter-observer and intra-observer agreement for measurements. Average radiation dose for both techniques. A total of 134 age-matched patients were included for measurement of MP. Thirty age-matched patients were included for AI measurements. Inter and intra-rater reliability of MP and AI were not different with or without use of the grid. There was a 50-75% decrease in radiation dose per radiograph following grid removal, dependent on patient size. The adjusted radiograph technique showed no significant difference in MP or AI reliability. A slight decrease in picture contrast did not jeopardize measurement reliability and decreased radiation exposure for the patient significantly. This simple technique can be useful for patients requiring multiple radiographs over time.

Evaluating the use of anti-scatter grids in adult knee radiography

INTRODUCTION

Anti-scatter grids efficiently reduce scatter radiation from reaching the imaging receptor, enhancing image quality; however, the patient radiation dose increases in the process. There is disagreement regarding the thickness thresholds for which anti-scatter grids are beneficial. This study aims to establish a thickness threshold for the use of anti-scatter grids to optimise adult knee radiography.

METHODS

The study consisted of two phases. In Phase 1 phantom knee radiographs were acquired at varying thicknesses (10-16 cm) and tube voltages (60-80 kV). For each thickness and tube voltage, images with and without an anti-scatter grid were obtained. In Phase 2, two radiologists and three radiographers, evaluated the image quality of these images. Visual Grading Analysis (VGA) scores were analysed using Visual Grading Characteristics (VGC) based on the visualisation of five anatomic criteria.

RESULTS

The average DAP decreased by 72.1% and mAs by 73.1% when removing the anti-scatter grid. The VGC revealed that overall images taken with an anti-scatter grid have better image quality (AUC ≥0.5 for all comparisons). However, the anti-scatter grids could be removed for thicknesses 10, 12 and 14 cm in conjunction with using 80 kVp,.

CONCLUSION

Anti-scatter grids can be removed when imaging adult knees between 10 and 12 cm using any kVp setting since the radiation dose is reduced without significantly affecting image quality. For thicknesses >12 cm, the use of anti-scatter grids significantly improves image quality; however, the radiation dose to the patient is increased. The exception is at 14 cm used with 80 kVp, where changes in image quality were insignificant.

IMPLICATIONS FOR PRACTICE

Optimisation by removing anti-scatter grids in adult knee radiography seems beneficial below 12 cm thickness with any kVp value. Since the average knee thickness ranges between 10 and 13 cm, anti-scatter grid can be removed for most patients. Nevertheless, further studies are recommended to test if this phantom-based threshold applies to human subjects.

Evaluation of the post-processing algorithms SimGrid and S-Enhance for paediatric intensive care patients and neonates

BACKGROUND

Post-processing software can be used in digital radiography to achieve higher image quality, especially in cases of scattered radiation. SimGrid is a grid-like software based on a Convolutional Neuronal Network that estimates the distribution and degree of scattered radiation in radiographs and thus improves image quality by simulating an anti-scatter grid. S-Enhance is an algorithm programmed to improve contrast visibility of foreign material.

OBJECTIVE

The objective of this study was to evaluate the SimGrid and S-Enhance digital radiography post-processing methods for neonatology and paediatric intensive care.

MATERIALS AND METHODS

Two hundred and ten radiographs from the neonatal (n = 101, 0 to 6 months of age) and paediatric (n = 109, 6 months to 18 years of age) intensive care units performed in daily clinical routine using a mobile digital radiography system were post-processed with one of the algorithms, anonymized and then evaluated comparatively by two experienced paediatric radiologists. For every radiograph, patient data and exposure data were collected and analysed.

RESULTS

Analysis of different radiographs showed that SimGrid significantly improves image quality for patients with a weight above 10 kg (range: 10-30 kg: odds ratio [OR] = 6.683, P < 0.0001), especially regarding the tracheobronchial system, intestinal gas, and bones. Utilizing S-Enhance significantly advances the assessment of foreign material (OR = 136.111, P < 0.0001) and bones (OR = 34.917, P < 0.0001) for children of all ages and weight, whereas overall image quality decreases.

CONCLUSION

SimGrid offers a differentiated spectrum in image improvement for children beyond the neonatal period whereas S-Enhance especially improves visibility of foreign material and bones for all patients.

Radiation use in diagnostic imaging in children: approaching the value of the pediatric radiology community

Medical imaging is foundational in the care of children, and much of the medical imaging province depends on ionizing radiation: radiography, fluoroscopy, CT and nuclear imaging. Many considerations for this imaging in children are distinct in the domains of appropriate radiation use, other factors that determine examination quality, the opportunities to engage and educate through networking, and the translation of research efforts. Given these needs, it is worth approaching the contributions and their impact by the pediatric radiology community, especially to the enhancement of this value in the care of children.

[Examination for Effectiveness of Scatter Correction in Portable Chest Radiography]

OBJECTIVES

The aim of this study was to evaluate the effectiveness of scatter correction in the portable chest radiography.

METHODS

Digital radiographies were performed without anti-scatter grid (grid), with the scatter correction and with the grid ratio of 3 : 1 in this study. The scatter fraction and the detectability of low contrast signals were measured using the four acrylic phantoms of different thicknesses. The chest phantom radiographs were assessed subjectively, in random order, by six radiologic technologists.

RESULTS

The scatter fraction was higher in the no-grid technique, and was lower for the grid technique. The detectability of low contrast signals did not significantly differ between the scatter correction and the grid technique (p>0.05). The area under the receiver operating characteristic curve for the grid technique was higher than that for the scatter correction technique (0.888 vs. 0.855), although no significant difference was found between the grid and the scatter correction technique (p> 0.05). The ability to detect the nasogastric tube was significantly better in the grid technique (p<0.001).

DISCUSSION

In the scatter correction technique, the ability of scatter removal increased as the scatter fraction increased. The scatter correction technique was unnecessary to extremely accurate alignment. In addition, patient dose can be reduced by the scatter correction technique.

CONCLUSIONS

It seemed to be effective for the scatter correction in the portable chest radiography.

Investigating the use of an antiscatter grid in chest radiography for average adults with a computed radiography imaging system

OBJECTIVE

The aim of this study was to investigate via simulation a proposed change to clinical practice for chest radiography. The validity of using a scatter rejection grid across the diagnostic energy range (60-125 kVp), in conjunction with appropriate tube current-time product (mAs) for imaging with a computed radiography (CR) system was investigated.

METHODS

A digitally reconstructed radiograph algorithm was used, which was capable of simulating CR chest radiographs with various tube voltages, receptor doses and scatter rejection methods. Four experienced image evaluators graded images with a grid (n = 80) at tube voltages across the diagnostic energy range and varying detector air kermas. These were scored against corresponding images reconstructed without a grid, as per current clinical protocol.

RESULTS

For all patients, diagnostic image quality improved with the use of a grid, without the need to increase tube mAs (and therefore patient dose), irrespective of the tube voltage used. Increasing tube mAs by an amount determined by the Bucky factor made little difference to image quality.

CONCLUSION

A virtual clinical trial has been performed with simulated chest CR images. RESULTS indicate that the use of a grid improves diagnostic image quality for average adults, without the need to increase tube mAs, even at low tube voltages.

ADVANCES IN KNOWLEDGE

Validated with images containing realistic anatomical noise, it is possible to improve image quality by utilizing grids for chest radiography with CR systems without increasing patient exposure. Increasing tube mAs by an amount determined by the Bucky factor is not justified.