Minimizing Radiation Exposure in Neonatal Intensive Care Unit: A Quality Improvement Approach on X-Ray Practices

Article information

Neonatal Med. 2024;31(3):56-64

Publication date (electronic) : 2024 November 30

doi : https://doi.org/10.5385/nm.2024.31.3.56

Jae Hui Ryu, MD¹, Seung Han Shin, MD, PhD^,2, Young Hun Choi, MD, PhD³, Ee-Kyung Kim, MD, PhD², Han-Suk Kim, MD, PhD²

¹Department of Pediatrics, Ewha Womans University Mokdong Hospital, Ewha Womans University College of Medicine, Seoul, Korea

²Department of Pediatrics, Seoul National University Children’s Hospital, Seoul National University College of Medicine, Seoul, Korea

³Department of Radiology, Seoul National University Children’s Hospital, Seoul National University College of Medicine, Seoul, Korea

Correspondence to: Seung Han Shin, MD, PhD Department of Pediatrics, Seoul National University Children’s Hospital, 101 Daehak-ro, Jongno-gu, Seoul 03080, Korea Tel: +82-2-2072-7230 Fax: +82-2-2072-3555 E-mail: revival421@snu.ac.kr

Received 2024 April 25; Revised 2024 October 24; Accepted 2024 October 24.

Abstract

INTRODUCTION

Over the past decades, the survival rates of high-risk preterm infants have improved with significant advancements in neonatal care. These vulnerable infants are susceptible to a range of conditions and complications including respiratory distress syndrome (RDS), bronchopulmonary dysplasia (BPD), patent ductus arteriosus (PDA), and necrotizing enterocolitis (NEC). Throughout their extensive and complex treatment in neonatal intensive care units (NICUs), newborns undergo numerous diagnostic procedures that require exposure to X-ray radiation. This issue is particularly pronounced in preterm infants with very low or extremely low birth weights and longer hospital stays [1,2]. Furthermore, the small body size of neonates often leads to additional exposure of irrelevant body parts during X-ray procedures, substantially contributing to the cumulative amount of radiation exposure [1,3].

Radiation exposure during childhood is possibly linked to an increased risk of developing solid tumors and leukemia in later life [4,5]. Furthermore, tissue sensitivity to radiation is inversely correlated with age, with younger patients having more susceptible tissues. This is critical among neonates, whose cells rapidly proliferate and differentiate, making them particularly vulnerable to the harmful effects of radiation [6]. Additionally, reports have indicated an increased risk of hepatoblastoma, germ cell tumors, and acute myeloid leukemia in preterm infants [7,8]. Therefore, the accumulated radiation exposure in these groups is likely to have even more detrimental effects.

Empirical studies, including a measurement of radiation dose in an NICU, indicate that the number of X-rays and radiation doses received during the NICU stay varies across centers, and the recommended actions based on measured radiation doses also vary widely. These results suggest a global inconsistency in addressing concerns about neonatal X-ray exposure, which presents a potential public health risk to this vulnerable neonatal group [9]. Based on this foundation, we implemented a quality improvement (QI) project in a level-IV NICU to reduce the cumulative radiation exposure to neonates during portable X-ray examinations.

MATERIALS AND METHODS

3. Intervention

We established two key drivers of our initiative (Figure 1). The first was to avoid excessive prescription of infantograms and the second was to minimize radiation exposure during X-ray imaging through optimal collimation. Ultimately, we aimed to achieve a reduction of over 30% in the average monthly cumulative DAP value per patient compared to the baseline. The DAP is a measure used to assess the total radiation energy delivered to a patient. It is defined as the absorbed dose multiplied by the irradiated area, and is expressed in Gy·cm² (graycentimeter square).

Figure 1.

Key driver diagram summarizing specific interventions. Abbreviation: NICU, neonatal intensive care unit.

1) Avoiding excessive prescription of infantograms

Patients admitted to the NICU underwent routine daily X-ray (infantogram) imaging for a certain period after birth, depending on their gestational age and clinical condition. Subsequently, the frequency of routine radiographic imaging was typically reduced based on the patient’s condition. However, unnecessary routine X-ray imaging was often performed, even in clinically stable patients, indicating the need for established protocols regarding appropriate X-ray imaging intervals and frequencies. Therefore, a protocol was proposed to minimize routine X-ray prescriptions for clinically stable patients. After the initial respiratory distress stabilized and sufficient enteral nutrition was achieved, the frequency of routine X-ray imaging was reduced to twice or thrice weekly, depending on the postmenstrual age.

• (1) For infants born at <32 weeks of gestation or weighing <1,500 g:

  • - During the first week of life (or until full enteral nutrition is achieved), a daily infantogram was taken.

  • - Afterwards, routine infantograms for screening purposes were limited to no more than three times a week.

  • - After 1 month of age, routine infantograms for screening purposes were limited to no more than twice a week.

• (2) For infants born at ≥32 weeks of gestation and weighing ≥1,500 g:

  • - For the first 3 days of life (or until full enteral nutrition is achieved), a daily infantogram was taken.

  • - Afterwards, routine infantograms for screening purposes were limited to no more than twice a week

  • - After 1 month of age, routine infantograms for screening purposes were limited to no more than once a week.

Infantograms of the chest and abdomen are critically needed for premature infants, particularly during the unstable early postnatal period. However, the DAP values, which reflect the radiation dose, significantly differed between infantograms and chest or abdominal radiographs alone [10]. Therefore, once preterm infants are stable after the initial postnatal period, it is recommended to replace infantograms with chest or abdominal radiographs as needed. For instance, (1) a chest radiograph alone may be performed to check the position of the tube in patients undergoing intubation and (2) an abdominal radiograph alone may be performed in cases where multiple rounds of checking the condition of the bowel at short intervals are required in situations such as when NEC is suspected or there is an impending risk of perforation.

We aimed to reduce the total number of infantogram sessions relative to the number of hospitalized patients by 20% compared to that before the implementation of QI activities through the establishment of guidelines for routine X-ray prescription protocols and the substitution of infantograms with chest or abdominal X-rays.

2) Achieving optimal collimation

Although the settings of the mobile radiography system were not changed, an internal rule was established among the radiographers to position the X-ray tube as high as possible during imaging. This approach increased the distance between the patient and the tube, potentially reducing the exposure field. Additionally, it standardized the variable distance between the patient and the tube across different radiographers, offering a consistent approach to minimize radiation exposure. Repeated educational sessions were conducted for the radiographers because this process extends beyond the establishment of internal regulations and necessitates heightened awareness and attention from all radiographers.

Furthermore, it is crucial to properly secure the target neonate to minimize movement, allowing the radiographer to cover only the minimum necessary area using an X-ray beam. To this effect, the NICU nurses were educated to ensure that they understood the importance of these activities. The goal was to achieve a 30% reduction in the average DAP value compared with that before the implementation of QI activities.

RESULTS

A total of 656 patients were included in the study, including 489 in the pre-intervention cohort (spanning 8 months; October 1, 2022, to May 31, 2023) and 167 in the post-intervention cohort (spanning 4 months; June 1, 2023, to September 30, 2023). Gestational age, birth weight, sex, mode of delivery, in-hospital birth status, length of stay, and mortality rate were not significantly different between the infants in either group (Table 1). Regarding infants born at <32 weeks of gestation or very low birth weight infants (birth weight <1,500 g), 106 were in the pre-intervention cohort, and 41 were in the post-intervention cohort. The rates of prematurity-related complications (air leak, pulmonary hemorrhage, pulmonary hypertension, RDS, moderate- to-severe BPD, symptomatic PDA, high-grade IVH, PVL, sepsis, NEC, SIP, and ROP) and mortality rates were not statistically different between the two groups (Table 2).

Table 1.

Baseline Characteristics of Overall Patients

Table 2.

Baseline Characteristics and Neonatal Morbidities of Patients Born at <32 Weeks of Gestational Age or with a Birth Weight <1,500 g

The average monthly number of admitted patients did not differ between the 8-month pre-intervention and 4-month postintervention periods (Table 3). The proportion of infantograms out of the total number of radiography orders showed a significant difference, dropping from 91% in the pre-intervention cohort to 83% in the post-intervention cohort (P=0.017). The average number of infantogram exposures per patient per month decreased notably from 25.91 to 21.24 (P=0.016) (Figure 2A). As a result of encouraging the substitution of infantograms with chest or abdomen X-rays whenever possible, the average number of chest and abdominal X-rays per patient per month increased from 0.39 to 2.25 (P=0.004) (Figure 2B). The average DAP value per X-ray decreased significantly from 0.25 dGy·cm² in the pre-intervention period to 0.14 dGy·cm² in the postintervention period (P=0.011) (Figure 3). Consequently, our primary outcome, the average monthly cumulative DAP value per patient, decreased by approximately half from 7.00 to 3.60 dGy·cm² (P=0.004) (Figure 4), achieving the target reduction of more than 30%.

Table 3.

Changes in Quality Improvement Metrics

Figure 2.

(A) U-chart of monthly number of infantogram per patient. (B) U-chart of monthly number of chest or abdominal X-ray per patient. Abbreviations: UCL, upper control limit; CL, center limit; LCL, lower control limit.

Figure 3.

Run chart of average dose-area product (DAP) value. Abbreviation: CL, center limit.

Figure 4.

U-chart of monthly cumulative dose-area product (DAP) value per patient. Abbreviations: UCL, upper control limit; CL, center limit; LCL, lower control limit.

DISCUSSION

A comparison of the periods before and after the implementation of the QI project revealed a reduction in the overall number of X-ray prescriptions and a significant decrease in the number of infantogram prescriptions, which covered the entire body and typically involved greater radiation exposure. The initiative to replace infantograms with chest or abdominal radiographs has led to an increase in the number of specific radiographs. Although efforts have been made to significantly reduce routine infantogram prescriptions, the incidence rates of events for which radiography plays a critical diagnostic role, such as air leaks, NEC, and intestinal perforation, showed no statistical difference. This indicates that reducing the number of X-ray exposures does not necessarily delay the diagnosis of these conditions provided that thorough patient monitoring and meticulous physical examinations are performed.

Additionally, through the practice of optimal collimation, which aimed to minimize radiation exposure for each shot, the average monthly DAP value per X-ray markedly decreased from 0.25 in the pre-intervention period to 0.14 in the postintervention period. This reduction played a crucial role in significantly surpassing the primary outcome goal of decreasing the average monthly cumulative DAP per patient. Remarkably, this was accomplished primarily through the efforts of radiographers who performed more precise collimation without any changes to the settings of the mobile radiography system. According to Stollfuss et al. [11], the only identifiable factor influencing the quality of collimation during chest radiography in preterm infants is the dedication and awareness of the radiographer. In their previous study, factors such as the infant's weight or size, presence of external lines or catheters, and even the radiographer's years of experience did not affect optimal collimation. Furthermore, numerous reports have indicated that collimation quality can be improved through high-quality education for radiographers [12,13].

Upon examining several international guidelines regarding diagnostic reference levels (DRLs), the health information and quality authority guideline suggests a DRL of 0.9 dGy·cm² for infants weighing <5 kg. The European Commission Recommendation advises a DRL of 1.5 dGy·cm² for chest X-rays and 4.5 dGy·cm² for abdomen X-rays in infants weighing <5 kg [14,15]. Studies that have differentiated infants by weight categories propose DRL recommendations as follows: for extremely low birth weight infants weighing <1,000 g, between 0.27 and 0.41 dGy·cm²; for preterm infants weighing between 1,000 and 2,000–2,500 g, between 0.37 and 0.72 dGy·cm²; and for newborns weighing over 2,000–2,500 g, between 0.61 and 0.66 dGy·cm² [10,16]. In our data, the DAP value per X-ray was maintained at lower levels than those recommended in international guidelines and numerous studies, regardless of the periods, with pre-intervention values at 0.25 dGy·cm² and post-intervention values at 0.14 dGy·cm².

By implementing reduced infantogram prescriptions and promoting strategies for optimal collimation, we achieved significant reductions in monthly cumulative radiation exposure for patients in the NICU. However, to further minimize exposure, it is essential to create adequate space between patients to reduce scatter radiation [17]. Furthermore, simple immobilization devices for babies can enhance image quality and reduce doses [18]. Leveraging radiation-free imaging modalities like ultrasonography, especially for procedures such as verifying catheter placement or assessing the position of endotracheal tubes, offers substantial benefits [19-21]. Lastly, safeguarding medical personnel with lead aprons and gloves and monitoring radiation exposure levels during procedures are crucial for comprehensive QI [22].

Our study had some limitations. First, although no cases of delayed diagnosis of complications such as air leaks, NEC, or intestinal perforation occurred during the observation period following the implementation of this QI project, the observation period was not long enough to rule out the occurrence of such adverse effects. Furthermore, efforts to minimize the area exposed to radiation for optimal collimation occasionally resulted in the need for retakes owing to inadequate image quality on the first attempt; however, data on the frequency of such retakes were not collected. Moreover, as this project depends heavily on the individual attentiveness of NICU physicians who prescribe X-ray orders and radiographers who perform collimations, there has been a noticeable decline in performance as their attention to duty has diminished. To address this issue, it is crucial to implement structured feedback in staff education, particularly by utilizing the Plan-Do-Study-Act cycle to ensure continuous performance improvement. Finally, although the cumulative DAP value per patient was significantly reduced, the long-term benefits of this reduction remain unclear. Therefore, a more detailed and long-term study is required to assess the effects of the radiation reduction project.

In conclusion, by discouraging excessive prescriptions of infantograms and promoting optimal collimation, we achieved a significant reduction in the average monthly cumulative DAP per patient. Despite the reduction in the number of infantogram exposures, no incidents of delayed diagnoses that could harm neonates have occurred. A major contributor to our encouraging results was the substantial decrease in the DAP value per X-ray, underscoring the critical role of the radiographers' dedication. Monitoring to ensure sustained implementation of this QI and designing studies to analyze the long-term benefits for infants are necessary.

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