Proper Management of the Clinical Exposure Index Based on Body Thickness Using Dose Optimization Tools in Digital Chest Radiography: A Phantom Study

Advancing Exposure Index in Radiology for Optimized Imaging, Accuracy, and Future Innovations

Exposure index (EI) is a critical parameter in digital radiography, providing a quantitative measure of the radiation dose received by the detector. This review examines the significance of EI, methods for its determination, influencing factors, and clinical implications. Additionally, it explores challenges in standardization efforts and the role of emerging technologies, particularly artificial intelligence (AI), in optimizing exposure management. A comprehensive review of literature published over the last two decades was conducted using databases such as PubMed, ScienceDirect, and Google Scholar. Studies addressing EI measurement, clinical applications, and advancements in exposure monitoring technology were analyzed. Guidelines from the International Electrotechnical Commission (IEC), the American Association of Physicists in Medicine (AAPM), and the European Federation of Organizations for Medical Physics (EFOMP) were also reviewed to assess standardization efforts and best practices. Findings highlight the importance of EI in radiation dose optimization and quality control. Despite standardization initiatives, variations persist across manufacturers and imaging systems due to factors such as patient characteristics, beam energy, detector sensitivity, and post-processing algorithms. Artificial intelligence-driven exposure monitoring systems have shown promise in enhancing EI accuracy and enabling real-time dose adjustments. Artificial intelligence technologies have the potential to revolutionize EI utilization by enabling automated exposure optimization, real-time monitoring, and predictive analytics. Future efforts should focus on refining AI algorithms, ensuring cross-platform standardization, and enhancing radiographer training to fully integrate AI into EI-based radiation safety protocols.

"Exposing" the exposure index: Navigating between image quality and radiation dose

INTRODUCTION

Deep knowledge of the properties and importance of the Exposure Index (EI) is crucial for delivering high-quality digital radiography images. This study aims to assess the EI on chest posterior anterior (PA) radiographic projection, demonstrating its correlation with parameters, such as body mass index (BMI), source-to-object distance (SOD), age, gender, and patient entrance skin dose (ESD).

METHODS

The study population included 805 patients who underwent a routine PA chest projection. All data were collected on an Agfa imaging system. Height and weight were also measured, and BMI was calculated. Descriptive statistics was used for data analysis, and inferential statistics was used for correlation analysis between EI, gender, age, ESD and BMI.

RESULTS

Over half (56.4%) of the study's participants were males; throughout the multivariate statistical correlation, increasing age was associated with increasing EI only in the female population (p=0.001). Ιn the lower BMI population subgroup, an increase in the SOD was associated with a decrease in the EI (p<0.001). Increasing BMI was associated with decreasing EI, while increasing ESD was linked to increased EI, except for those with lower or higher BMI, where no statistically significant relationship was observed (p=0.403 and p=0.445, respectively).

CONCLUSION

Analysis of the intercorrelation between important parameters such as the EI, BMI, ESD, SOD, age and gender can prove useful for radiographers, offering the ability to deliver high-quality diagnostic chest images, whilst also establishing the EI as an important and highly significant factor.

Feasibility of new patient dose management tool in digital radiography: Using clinical exposure index data of mobile chest radiography in a large university hospital

The clinical anteroposterior (AP) chest images taken with a mobile radiography system were analyzed in this study to utilize the clinical exposure index (EI) as a patient dose-monitoring tool. The digital imaging and communications in medicine header of 6048 data points exposed under the 90 kVp and 2.5 mAs were extracted using Python for identifying the distribution of clinical EI. Even under the same exposure conditions, the clinical EI distribution was 137.82-4924.38. To determine the cause, the effect of a patient's body shape on EI was confirmed using actual clinical chest AP image data binarized into 0 and 255-pixel values using Python. As a result, the relationship between the direct X-ray area of the chest AP image, the higher the clinical EI, the larger the rate of the direct X-ray area. A conversion equation was also derived to infer entrance surface dose through clinical EI based on the patient thickness. This confirmed the possibility of directly monitoring patient dose through EI without a dosimeter in real-time. Therefore, to use the clinical EI of the mobile radiography system as a patient dose-monitoring tool, the derivation method of clinical EI considers several factors, such as the relationship between patient factors.

Comparison of organ dose from chest radiography with varying beam quality and constant exposure index

The optimum X-ray tube voltage for chest radiographic examinations remains unclear; hence, the tube voltage varies between medical facilities. An exposure index (EI) was proposed to standardize the parameters for radiographic examinations. However, even if identical EI values are used to examine the same person, organ doses may vary due to differences in tube voltages. In this study, the variation in organ doses between different beam qualities under identical EI values for chest radiographic examinations was investigated using Monte Carlo simulations. A focused anti-scatter grid as well as standard and larger physique-type medical internal radiation dose (MIRD) phantoms were studied under tube voltages of 90, 100, 110, and 120 kVp. The organ doses in the MIRD phantom increased as the X-ray tube voltage decreased, even with identical EI values. The absorbed doses in the lungs of standard and large-sized MIRD phantoms at 90 kVp were 23% and 35% higher than those at 120 kVp, respectively. The doses to organs other than the lung at 90 kVp were also higher than those at 120 kVp. From the perspective of reducing radiation doses, a tube voltage of 120 kVp is considered better for chest examinations compared with a tube voltage of 90 kVp under identical EI values.

Exposure index in digital radiography: initial results of awareness and knowledge from Nigerian digital radiography practices

INTRODUCTION

Exposure Index (EI) is incorporated into Digital Radiography (DR) systems to indicate incorrect exposure to enable matching exposure to the desired speed class of operation. However, knowledge of the utilization of EI by radiographers in a low-income country has not been investigated.

METHODS

A pre-tested questionnaire designed using Google forms, with open and close-ended questions was shared online with radiographers working with DR systems in public and private health facilities in some cities located in southern Nigeria. The 32-item questionnaire had two parts: Part A focused on socio-demographic characteristics and Part B focused on the respondents' awareness and knowledge of EI in DR systems. A 5-point Likert scale with 5 test items was used to assess the respondents' knowledge of EI. Statistical analyses were conducted using the Statistical Package for Social Sciences (SPSS) version 21.0. The probability value of p < 0.05 was considered statistically significant.

RESULTS

About 8.3% of the respondents had good knowledge of EI in DR systems in spite of the awareness level of 24.7%. The absence of the EI concept in DR curriculum for undergraduates, the lack of EI software in DR systems, and equipment training by the vendor engineers were reasons for the low level of knowledge of EI in DR systems.

CONCLUSION

There is low awareness and knowledge of EI by radiographers in this study, which suggests the need to maximize the benefits of EI concepts by ensuring its integration into clinical radiography practice and curriculum for undergraduates program, to improve knowledge, awareness, and practice in DR.

Monitoring clinical exposure index and deviation index for dose optimization based on national diagnostic reference level: Focusing on general radiography of extremities

BACKGROUND

The International Electrotechnical Commission established the concept of the exposure index (EI), target exposure index (EIT) and deviation index (DI). Some studies have conducted to utilize the EI as a patient dose monitoring tool in the digital radiography (DR) system.

OBJECTIVE

To establish the appropriate clinical EIT, this study aims to introduce the diagnostic reference level (DRL) for general radiography and confirm the usefulness of clinical EI and DI.

METHODS

The relationship between entrance surface dose (ESD) and clinical EI is obtained by exposure under the national radiography conditions of Korea for 7 extremity examinations. The EI value when the ESD is the DRL is set as the clinical EIT, and the change of DI is then checked.

RESULTS

The clinical EI has proportional relationship with ESD and is affected by the beam quality. When the clinical EIT is not adjusted according to the revision of DRLs, there is a difference of up to 2.03 in the DI value and may cause an evaluation error of up to 1.6 times for patient dose.

CONCLUSIONS

If the clinical EIT is periodically managed according to the environment of medical institution, the appropriate patient dose and image exposure can be managed based on the clinical EI, EIT, and DI.