Tungsten-bismuth shielding sheets for radiation safety in fluoroscopy-guided bronchoscopy: a phantom study

Abstract

Background

Radiation safety is a critical concern in fluoroscopy-guided bronchoscopy. While standard personal protective equipment (PPE) such as lead aprons, thyroid collars, and eyewear protects vulnerable regions, other areas remain exposed. Supplemental shielding (e.g., glass screens, table skirts) can improve safety, but ceiling-mounted lead-acrylic barriers, though effective, are limited by cost and space. This study evaluated tungsten-bismuth (W-Bi) shielding sheets as a low-cost, deployable alternative.

Methods

Using a C-arm fluoroscope (65 kVp, 4.2 mA) on an anthropomorphic phantom, we compared the attenuation performance, weight, and cost of PPE and structural shielding devices. Scatter radiation was measured at four vertical heights (50–170 cm) to simulate body-level exposures, with additional hand-level assessments for the bronchoscopist and assistant. Over-couch protection was tested across five conditions: no shielding, lead-acrylic barrier (0.50 mmPb), and single to triple layers of W-Bi sheets (0.15 mmPb each).

Results

Lead-acrylic and ≥ double-layer W-Bi achieved >96% dose reduction across most body regions, excluding the thigh. Triple-layer W-Bi sheets provided up to 98.8% attenuation at the upper thorax and >99% reduction at hand level, surpassing lead-acrylic in some measurements. The assistant’s hand received the highest unshielded dose (2,439.47±11.19 µGy/h), over threefold greater than the bronchoscopist’s. Combined PPE and structural shielding yielded markedly enhanced protection, particularly in regions not covered by PPE.

Conclusions

Triple-layer W-Bi shielding offers radiation protection comparable to or exceeding lead-acrylic barriers. Its affordability and ease of deployment support its use as a practical strategy for improving radiation safety in bronchoscopy, especially in resource-limited settings.

Highlight box.

Key findings

• Triple-layer tungsten-bismuth (W-Bi) shielding sheets reduced scatter radiation by >98% at the bronchoscopist’s torso and >99% at hand level, comparable to or exceeding ceiling-mounted lead-acrylic barriers.

• W-Bi sheets cost less than 5% of conventional lead-acrylic barriers ($585 vs. $14,000).

• Integration of W-Bi shielding with personal protective equipment (PPE) markedly enhanced overall protection, especially in anatomical regions not adequately covered by PPE.

What is known and what is new?

• Fluoroscopy-guided bronchoscopy exposes operators and assistants to significant scatter radiation. PPE reduces risk but leaves some anatomical regions unprotected. Ceiling-mounted lead-acrylic barriers are effective but costly and difficult to implement in many bronchoscopy suites.

• This study provides the first bronchoscopy-specific evaluation showing W-Bi sheets as an affordable, deployable alternative with comparable protection.

What is the implication, and what should change now?

• W-Bi shielding offers a practical solution for radiation safety in bronchoscopy, especially in resource-limited or space-constrained settings.

• Clinical validation is warranted to support wider adoption in interventional pulmonology.

Introduction

Background

Fluoroscopy-guided bronchoscopy plays a pivotal role in diagnosing peripheral pulmonary lesions by providing real-time imaging that enhances procedural precision and diagnostic accuracy (1). Despite the inherent challenges in navigating complex airway anatomy and locating peripheral targets, recent technological advancements—including augmented fluoroscopy, digital tomosynthesis, and robotic-assisted bronchoscopy integrated with cone-beam computed tomography (CBCT)—have markedly improved lesion localization, sampling accuracy, and procedural control (2). These advancements have further emphasized the critical role of fluoroscopy in the practice of interventional pulmonology.

Rationale and knowledge gap

Given the increasing reliance on fluoroscopy in interventional pulmonology, growing awareness of scattered radiation exposure among healthcare professionals has emphasized the importance of effective protective strategies. Although modern fluoroscopy systems incorporate safety mechanisms designed to minimize exposure for both patients and healthcare professionals (3), strict compliance with the As Low As Reasonably Achievable (ALARA) principle remains critical (4). Achieving ALARA in practice requires a multifactorial approach: reducing fluoroscopy time, maintaining optimal distance from radiation sources, and implementing appropriate protection equipment, with system optimization technology playing a pivotal role (5,6).

From a procedural standpoint, fluoroscopy‑guided bronchoscopy typically employs an under-couch X-ray tube configuration, with the primary beam directed toward the patient’s thorax. As the bronchoscopist and assistant are positioned cranially near the patient’s head, they are generally outside the primary radiation field. Nevertheless, substantial occupational exposure may still occur due to scattered radiation generated by the patient and surrounding structures, which impacts the healthcare professional’s entire body.

The white paper issued by the World Association of Bronchology and Interventional Pulmonology (WABIP) advocates the use of supplementary shielding techniques—such as glass screens and table skirts—in addition to personal protective equipment (PPE), which is considered essential for mitigating radiation risks (7). While conventional PPE—including lead aprons, thyroid collars, and protective eyewear—offers shielding for anatomical regions most vulnerable to radiation exposure, numerous anatomical sites remain susceptible due to practical limitations in PPE application. Emerging evidence indicates that combination of shielding barriers can significantly reduce operator exposure during bronchoscopy procedures (8). By integrating various protection equipment—such as over-couch lead-acrylic panels, under-couch skirts, and patient drapes—clinicians can effectively minimize scatter radiation across a range of anatomical regions, enhancing occupational safety without compromising procedural efficacy. While under-couch shielding solutions are relatively straightforward to implement, over-couch protection—such as ceiling-mounted lead-acrylic panels—typically requires ceiling-mounted suspension arm, presenting substantial financial and spatial challenges that hinder widespread clinical adoption.

Recently, a novel X-ray shielding material composed of a light-weight and highly attenuating tungsten-bismuth (W-Bi) composite has been developed (9,10). This lead-free material is currently being utilized in fluoroscopy guided intervention settings to drape over patients’ bodies, effectively attenuating scattered radiation and enhancing procedural safety (11,12).

Objective

This study introduces a low-cost, portable W-Bi shielding system designed in a curtain-style configuration to supplement standard PPE. The objective is to evaluate its shielding efficacy compared with conventional ceiling-mounted lead-acrylic barriers in a bronchoscopy-specific phantom study. By assessing attenuation performance, weight, and cost, this study explores the feasibility of W-Bi shielding sheets as a scalable, adaptable, and clinically viable solution for radiation protection in fluoroscopy-guided bronchoscopy.

Methods

Assessment of radiation attenuation, cost, and weights of shielding devices and PPE

The radiation attenuation efficacy of various protective equipment was evaluated using direct X-ray beam generated by a mobile C-arm fluoroscopy unit (Cios Select, Siemens Healthineers, Forchheim, Germany). The direct X-ray beam was positioned beneath the table, and each protective equipment to be evaluated was placed on the tabletop. A gamma survey meter (PM1401K-3P, Polimaster, Minsk, Belarus) was then placed on top of the protective equipment to measure radiation exposure. To calculate attenuation efficiency of each protective equipment, dose rates were measured with and without each protective equipment, and the relative dose reduction was used to assess shielding performance.

Shielding barriers included a couch-mounted lower skirt with 0.5 mmPb equivalence, a ceiling-mounted lead-acrylic shield (OT94001, MAVIG, Munich, Germany) also rated at 0.5 mmPb, and W-Bi composite shielding sheets (PK-RAS01, Pentas Korea Co., Ltd., Busan, South Korea) arranged in single, double, or triple layers, with each layer estimated to provide approximately 0.15 mmPb equivalence. The PPE included lead aprons (N-XR-4, Nicemedica, Seoul, South Korea) designed to protect the torso from the upper chest to the lower abdomen, with nominal lead equivalences of 0.25 and 0.5 mmPb. For eye protection, two types of leaded eyewear were evaluated: a full-frame model (Nike Brazen, EV-0571-001) with a lead equivalence of 0.75 mmPb, and an open-frame model (X-XR-E-1, Nicemedica) with a lead equivalence of 0.12 mmPb.

A comparative analysis of shielding barriers and PPE was conducted to evaluate their cost, weight, and accessibility across varying economic conditions, while also accounting for the physical burden PPE imposes on healthcare professionals. This assessment offers practical insight into the affordability and scalability of shielding solutions, balancing protective efficacy with financial feasibility. Table 1 summarizes the type, model, lead equivalence, placement coverage, and key characteristics of each device evaluated in this study.

Table 1. Summary of radiation shielding devices and PPE evaluated for fluoroscopy-guided bronchoscopy.

Category	Type/model	Lead equivalence	Placement/coverage	Remarks
Shielding device	Couch-mounted lower skirt	0.5 mmPb	Mounted below tabletop	Reduces scatter from under-table beam
	Lead-acrylic shield (OT94001, MAVIG)	0.5 mmPb	Ceiling-suspended	Transparent, covers upper body
	W-Bi composite sheet (PK-RAS01)	~0.15 mmPb per layer	Suspended on movable rack	Tested in single/double/triple layers
PPE	Lead apron (N-XR-4, Nicemedica)	0.25 mmPb, 0.5 mmPb	Upper chest to lower abdomen	Two levels of protection tested
	Leaded eyewear—full-frame (Nike Brazen)	0.75 mmPb	Eyes (full-frame)	Higher protection, more enclosed
	Leaded eyewear—open-frame (X-XR-E-1)	0.12 mmPb	Eyes (open-frame)	Lighter, less coverage

PPE, personal protection equipment.

Experimental setup and measurement locations

To characterize bronchoscopy-specific radiation exposure patterns, anthropomorphic phantoms with human-equivalent attenuation and scatter properties were used to simulate procedure-specific scatter fields. Scattered radiation was analyzed and evaluated at cranial positions near the patient’s head, corresponding to typical clinical posture and hand placement of the operator. An anthropomorphic chest phantom (N1 Lungman, Kyoto Kagaku, Kyoto, Japan) and a head phantom (PH-47, Kyoto Kagaku, Japan) were positioned on a patient couch. A mobile C-arm X-ray fluoroscopy unit was used, with the X-ray tube located below the couch to generate realistic scattered radiation. The focal spot of the X-ray tube was positioned 30 cm above the floor, and the source-to-couch distance was set at 50 cm.

The primary measurement point for the bronchoscopist was established 50 cm cranially from the center of the X-ray tube. Dose rates were recorded at four vertical heights corresponding to key anatomical landmarks: glabella level (170 cm), upper thorax (130 cm), hypogastrium (90 cm), and thigh region (50 cm). Additionally, radiation exposure to the hands of the bronchoscopist and assistant was measured. The assistant was assumed to be holding the bronchoscope in front of the patient’s mouth. Hand dose measurements were taken 25 cm cranially from the X-ray source at 130 cm (bronchoscopist’s hand level) and 90 cm (assistant’s hand level) height.

Fluoroscopy parameters were fixed at 65 kVp and 4.2 mA, with pulsed fluoroscopy operating at 30 frames per second. Measurements were conducted in triplicate for each shielding condition and position using a gamma survey meter.

Over-couch shielding scenarios with ceiling-mounted lead-acrylic barrier and multiple layers of W-Bi sheets

A lead-equivalent skirt mounted beneath the couch was applied consistently across all experimental scenarios to provide baseline under-couch radiation protection. While over-couch shielding configurations were varied according to group assignment to evaluate their respective efficacy in attenuating scattered radiation. Scattered dose attenuation was assessed under five distinct shielding conditions, designed to enable a comparative analysis of protective performance. The shielding scenarios tested were as follows: (I) no additional over-couch shielding (control condition); (II) a ceiling-mounted lead-acrylic barrier; (III) single layer of the W-Bi shielding sheets suspended on a movable clothing rack; (IV) double layers of the W-Bi shielding sheets; and (V) triple layers of the W-Bi shielding sheets.

The commercial lead-acrylic barrier was suspended from the ceiling and featured a lead equivalence of 0.5 mmPb, with dimensions of 78 cm × 90 cm. To enhance its protective coverage, 0.5 mmPb X-ray protective strips and drapes were affixed beneath the acrylic panel to minimize open gaps that could allow the transmission of scattered radiation.

The proposed W-Bi shielding sheets was fabricated from a composite of specially processed bismuth, antimony, and tungsten powder. Each individual sheet measured 45 cm × 35 cm, with an estimated lead equivalence of approximately 0.15 mmPb under primary X-ray exposure conditions. Six sheets were interconnected and suspended on a movable stand positioned above the phantom’s neck, providing targeted protection against scattered radiation for both the bronchoscopist and the assistant. Attenuation performance was evaluated using single, double, and triple overlapping layers of the shielding material to assess the dose reduction effect as a function of shielding thickness. The overall experimental setup and shielding scenarios is described in Figure 1.

Figure 1.

Overview of the experimental setup, measurement locations, shielding devices, and test scenarios: (1) under-couch curtain only, (2) a ceiling-mounted lead-acrylic barrier (model OT54001, MAVIG, Germany), (3) single, double, and triple layers of W-Bi composite. W-Bi, tungsten-bismuth.

Integrated attenuation performance of shielding devices used in conjunction with PPE

In real clinical settings, PPE is routinely worn as the primary layer of protection, while additional shielding barriers are applied based on user preference and feasibility. The radiation attenuation efficacy of PPE was integrated with the measured values obtained under over-couch shielding scenarios to derive the total shielding performance at the bronchoscopist torso site. The attenuation performance was calculated under six conditions: (I) lightweight PPE alone; (II) heavyweight PPE alone; (III) lightweight PPE combined with ceiling-mounted lead-acrylic panels; (IV) heavyweight PPE combined with ceiling-mounted lead-acrylic panels; (V) lightweight PPE combined with triple-layered W-Bi composite sheets; and (VI) heavyweight PPE combined with triple-layered W-Bi composite sheets. PPE configurations included protective aprons and leaded eyewear, with aprons rated at 0.25 and 0.5 mmPb considered lightweight and heavyweight, respectively. Protective glasses with lead equivalence of 0.12 mmPb were classified as lightweight, while those with 0.75 mmPb were considered heavyweight. This framework enabled a systematic comparison of shielding performance across varying combinations of wearable and structural protection, aimed at identifying optimal strategies for minimizing radiation exposure during bronchoscopy.

Statistical analysis

To quantitatively evaluate the radiation attenuation performance of each protective configuration, the shielding efficacy was calculated for all tested PPE and shielding barrier conditions. The shielding efficacy for each configuration was calculated as the percentage reduction in radiation dose compared to the unshielded baseline, using the formula:

$$\text{Shielding\hspace{0.17em}efficacy}\left(\%\right)=\left(1-D\text{shielded}/D\text{unshielded}\right)\times 100$$ [1]

where Dshielded represents the measured dose with the shielding material in place, and Dunshielded represents the dose without any shielding. Each measurement was repeated three times to ensure reproducibility, and the mean value was used for analysis.

One-way analysis of variance (ANOVA) was used to compare dose values among all shielding groups (no shielding, lead acrylic, and single, double, and triple-layers W-Bi shielding) at each height. Post hoc comparisons were conducted using Tukey’s Honestly significant difference (HSD) test. A P value <0.05 was considered statistically significant. All statistical analyses were performed using Python (SciPy and statsmodels packages).

Results

Attenuation efficacy, weights, and cost analysis of shielding devices and PPE

Under direct exposure to the primary X-ray beam, the ceiling-mounted lead-acrylic shielding system demonstrated a high shielding efficacy of 99.58%. In comparison, the W-Bi composite shielding sheet achieved attenuation rates of 84.73% with a single layer, 95.80% with a double-layer configuration, and 98.28% with a triple-layer arrangement, as detailed in Table 2. The under-couch curtain, easily applicable in clinical settings and composed of overlapping 0.5 mmPb sheets, demonstrated a shielding efficacy of 97.49%. Within the category of PPE, attenuation efficacy varied according to lead equivalence and design. The 0.5 mmPb apron achieved a 99.03% attenuation rate, outperforming the 0.25 mmPb apron, which showed 94.55%. For eye protection, full-frame leaded glasses (0.75 mmPb equivalence) demonstrated superior shielding with 99.19% attenuation, whereas the open-frame variant (0.12 mmPb equivalence) exhibited significantly lower efficacy at 85.58%. A comprehensive comparison of shielding efficacy, cost, and weight for all device types is presented in Table 2.

Table 2. Shielding efficacy under primary X-ray beam irradiation conditions, weights, and cost of protective equipment (P<0.001).

Parameters	Structural shielding devices						PPE
	Ceiling-mounted lead acrylic (including ceiling-mounted system)	W-Bi composite shielding sheet			Under couch curtain 0.5 mmPb		Apron 0.5 mmPb	Apron 0.25 mmPb	Full-frame with 0.75 mmPb Glasses	Open-frame with 0.12 mmPb Glasses
		Single-layer (6 sheets)	Double-layer (12 sheets)	Triple-layer (18 sheets)
Shielding efficacy (%)	99.58	84.73	95.80	98.28	97.49		99.03	94.55	99.19	85.58
†Cost ($)	7,900 (14,255)	195	390	585	1,200		470	360	640	510
†Weight (kg)	15 (50)	2.82	5.64	8.46	9.07		3.67	2.23	0.08	0.07

^†, Values in parentheses indicate the total cost or weight including the ceiling-mounted suspension system. PPE, personal protection equipment; W-Bi, tungsten-bismuth.

Significant cost differences were observed among the shielding configurations. The ceiling-mounted lead-acrylic including ceiling-mounted system was the most expensive option, priced at approximately $14,255. In contrast, the W-Bi shielding sheets offered more economical alternatives: a single-layer arrangement (six sheets) cost $195, while the triple-layer configuration totaled $585. PPE also exhibited a range of prices. The 0.5 mmPb apron was priced at $470, and the 0.25 mmPb apron at $360. For eye protection, full-frame leaded glasses (0.75 mmPb equivalence) were priced at $640, whereas the open-frame variant (0.12 mmPb equivalence) cost $510.

Device weight was also evaluated as a key factor in determining the practicality of each shielding configuration. The ceiling-mounted lead-acrylic system weighed approximately 15 kg, increasing to nearly 50 kg when including the structural mounting apparatus. In contrast, the triple-layer W-Bi shielding sheets were substantially lighter, with a combined weight of 8.46 kg. PPE items varied in weight depending on their lead equivalence. The 0.5 mmPb apron weighed 3.67 kg, whereas the 0.25 mmPb apron was considerably lighter, with a weight of 2.23 kg. For eye protection, full-frame leaded glasses weighed 0.08 kg, and open-frame glasses weighed 0.07 kg. A comprehensive comparison of shielding efficacy, cost, and weight for all device types is presented in Table 2.

Comparing the shielding efficacy of over-couch configurations, ceiling-mounted lead-acrylic barriers and layered W-Bi composite sheets

Radiation exposure varied significantly across measurement sites depending on the shielding configuration (P<0.001, Table 3). Without over-couch shielding, the bronchoscopist’s torso—50 cm cranial to the X-ray source—received scattered dose rates from 1.11±0.09 µGy/h at the thigh to 708.25±7.28 µGy/h at the upper thorax, the highest exposure. The low thigh dose likely reflects passive attenuation from the operating table’s structure, including the central support column and couch curtain. The triple-layer W-Bi sheet was most effective, reducing exposure by 98.75% (upper thorax), 97.60% (hypogastrium), and 98.57% (glabella). Lead-acrylic barriers showed similar efficacy: 97.05%, 97.41%, and 98.74% at the same landmarks. In contrast, single-layer W-Bi sheets were less effective, with attenuation ranging from 86.03% to 94.86% depending on height. At the hand level (25 cm cranial to the X-ray tube), the assistant’s hand at 90 cm height recorded the highest scattered radiation dose under unshielded conditions: 2,439.47±11.19 µGy/h—more than three times the dose measured at the bronchoscopist’s hand positioned at 130 cm (743.46±5.05 µGy/h). With shielding, triple-layer W-Bi sheets reduced exposure by 99.10% and 99.71% for the assistant and bronchoscopist, respectively. These attenuation levels were comparable to those achieved by the lead-acrylic barrier, which provided 99.31% and 99.84% reduction, respectively. Table 3 summarizes dose rates and shielding efficacy across key body positions under five configurations.

Table 3. Dose rates and shielding efficacy measured at representative positions corresponding to each body part of the bronchoscopist and assistant under five shielding conditions (P<0.001) (65 kVp, 4.2 mA).

Location	H (cm)	No shielding		Lead acrylic			W-Bi composite shielding sheet
							Single-layer			Double-layer			Triple-layer
		$\dot{D}$ (μGy/h)		$\dot{D}$ (μGy/h)	Eff. (%)		$\dot{D}$ (μGy/h)	Eff. (%)		$\dot{D}$ (μGy/h)	Eff. (%)		$\dot{D}$ (μGy/h)	Eff. (%)
Bronchoscopist’s torso (50 cm cranially)	170 (glabella)	230.32±2.63		2.90±0.04	98.74		11.84±0.82	94.86		3.25±0.10	98.59		3.28±0.12	98.57
	130 (upper thorax)	708.25±7.28		20.90±0.12	97.05		80.17±0.89	88.68		20.39±0.34	97.12		8.82±0.10	98.75
	90 (hypogastrium)	444.98±5.12		11.50±0.50	97.41		62.17±0.27	86.03		16.39±0.14	96.32		10.69±0.14	97.60
	50 (thigh)	1.11±0.09		0.82±0.06	26.43		0.33±0.02	70.57		0.44±0.03	60.66		0.13±0.01	88.29
Bronchoscopist (25 cm cranially)	130 (hand)	743.46±5.05		1.2±0.05	99.84		53.95±0.42	92.74		6.90±0.21	99.07		2.18±0.14	99.71
Assistant (25 cm cranially)	90 (hand)	2,439.47±11.19		16.76±0.30	99.31		255.34±0.19	89.53		59.91±1.43	97.54		21.92±0.29	99.10

Data are presented as mean ± standard deviation. $\dot{D}$, dose rate; Eff., efficacy; H, height; W-Bi, tungsten-bismuth.

These findings are also visually summarized in Figure 2, where the mean scattered dose rates and shielding efficacy are illustrated across five experimental setups. Figure 2A presents data obtained at 50 cm cranial to the X-ray source, while Figure 2B displays measurements taken at 25 cm cranial.

Figure 2.

Comparison of mean scattered dose rates under four shielding configurations relative to the unshielded condition (P<0.01 for all comparisons). (A) Measurements acquired 50 cm cranially from the X-ray source center, where additional shielding using PPE is feasible. (B) Measurements acquired 25 cm cranially from the X-ray source center, where effective supplemental shielding with PPE is impractical due to spatial constraints. PPE, personal protection equipment.

Integrated attenuation performance of ceiling-mounted lead-acrylic barriers or layered W-Bi composite sheets combined with PPE

Integrated shielding performance at the bronchoscopist’s torso was calculated by combining PPE attenuation with over-couch shielding. Lightweight PPE (0.25 mmPb apron and 0.12 mmPb lead glasses) yielded a dose rate ratio of 5.4–14.4%, whereas heavyweight PPE (0.5 mmPb apron and 0.75 mmPb lead glasses) demonstrated a significantly lower dose rate ratio of 0.81–0.97%, indicating superior protective capacity (P<0.001; shown in Figure 3).

Figure 3.

Dose rate ratio (with/without shielding) measured at different heights (50, 90, 130, and 170 cm) for various shielding conditions. At 50, 90, and 130 cm, shielding was applied using protective aprons with lead equivalences of 0.25 and 0.50 mmPb. At 170 cm, protective glasses with lead equivalences of 0.12 and 0.75 mmPb were used. Each bar represents the dose rate reduction under different shielding combinations, including PPE alone, lead acrylic with PPE, and W-Bi composite sheets with PPE. Lower dose rate ratios indicate more effective radiation shielding performance. Values below 0.001 are displayed at the minimum scale of the axis and may not be visually distinguishable due to scale compression. PPE, personal protection equipment; W-Bi, tungsten-bismuth.

However, when combined with structural shielding—either ceiling-mounted lead-acrylic panels or W-Bi composite sheets—the disparity in attenuation efficacy between PPE configurations was markedly diminished. Attenuation levels reached 0.14–4.01% for lightweight PPE and 0.01–0.71% for heavyweight PPE in conjunction with lead-acrylic panels, and 0.07–0.90% versus 0.01–0.11% when paired with W-Bi composite sheets. These marginal differences (<0.8%) indicate that the implementation of high-performance over-couch shielding effectively compensates for the lower attenuation capacity of lightweight PPE, resulting in comparable protective performance across both configurations under shielded conditions.

Figure 4 presents post-shielding measurements with PPE-adjusted calculations (µGy/h) at various anatomical sites, including heights of 50, 90, 130, and 170 cm; 50 cm cranial to the X-ray tube; and hand-level positions at 90 and 130 cm height, located 25 cm cranial to the X-ray tube, under over-couch shielding conditions. Additional attenuation was calculated based on PPE efficacy where applicable. However, at the hand level—25 cm cranial to the X-ray tube, corresponding to the assistant’s position at 90 cm and the bronchoscopist’s at 130 cm—PPE cannot be applied, and therefore no additional attenuation was included. At these sites, the absence of structural shielding devices results in substantial exposure to scattered radiation.

Figure 4.

Post-structural shielding measurements with PPE-adjusted calculations (µGy/h) at bronchoscopist’s anatomical heights of 50, 90, 130, and 170 cm, and at hand-level positions 25 cm above the X-ray tube (90 and 130 cm). Green bars denote unshielded dose rates. PPE included a 0.25 mmPb apron (50–130 cm) and 0.12 mmPb glasses (170 cm). Additional shielding comprised lead-acrylic and W-Bi sheets in combination with PPE. At hand level, where PPE cannot be applied, doses were measured under structural shielding only (none, lead-acrylic, W-Bi). *, denotes positions 25 cm cranial to the X-ray tube. PPE, personal protection equipment; W-Bi, tungsten-bismuth.

Discussion

This study demonstrates the effectiveness of a triple-layer W-Bi composite shielding system in reducing scatter radiation during simulated fluoroscopy-guided bronchoscopy. The W-Bi system achieved over 98% attenuation at key anatomical sites and over 99% at high-exposure zones like the hands. Its performance was comparable to or better than conventional ceiling-mounted lead-acrylic barriers. Given its low cost and high efficacy, the W-Bi system offers a practical alternative in settings with spatial, mobility, or budget constraints. Structural shielding complements PPE by enhancing protection in covered areas and serving as the primary defense where PPE is insufficient.

A white paper on radiation safety in bronchoscopy has emphasized the importance of implementing additional shielding devices beyond standard PPE (7), and previous studies have shown the effectiveness of ceiling-mounted lead-acrylic shielding systems in reducing scattered radiation during fluoroscopy guided bronchoscopy (8). However, the adoption of these systems in bronchoscopy suites is often impeded by spatial constraints and financial limitations. Although non-lead shielding sheets have shown promise in other fluoroscopic interventional procedures (13-15), their applicability to bronchoscopy-specific environments has not been previously examined. The geometry of bronchoscopy is distinct from other interventional procedures due to its unique spatial arrangement of the X-ray source, patient, and bronchoscopist, requiring a customized shielding approach. This study offers the first phantom-based assessment of W-Bi shielding sheets under simulated bronchoscopy conditions. The results suggest that W-Bi shielding may represent a practical and economically favorable option compared to conventional ceiling-mounted systems, especially in the settings where physical space or budget constraints limit the feasibility of a ceiling-mounted protection system.

The observed differences in shielding effectiveness among the evaluated devices can be attributed to variations in material composition, density, shielding geometry, and effective thickness, as well as the energy spectrum of scattered radiation encountered during bronchoscopy. Tungsten and bismuth, as high-atomic number elements, exhibit pronounced photoelectric absorption in the low- to intermediate-energy range characteristic of scattered fluoroscopic X-rays (16). When arranged in multiple overlapping layers, the W-Bi composite sheets increase effective attenuation thickness while maintaining flexibility, consistent with the exponential attenuation behavior described by the Beer-Lambert law, thereby enhancing absorption of obliquely incident scatter radiation. In contrast, ceiling-mounted lead-acrylic barriers provide uniform attenuation primarily through a single rigid panel; however, their shielding performance may be influenced by geometric gaps. These findings support the potential role of multilayer W-Bi shielding as an effective supplemental structural protection strategy when combined with standard PPE, warranting further validation in clinical practice.

The W-Bi shielding system demonstrates notably low-cost, with the complete setup—including a movable clothing rack and accessories—costing approximately $600. This stands in stark contrast to conventional ceiling-mounted systems, which typically exceed $14,000. In addition to its favorable cost profile, the W-Bi system offers several ergonomic and operational benefits that support its adoption in clinical practice. Weighing approximately 8.46 kg for the full three-layer configuration, the system imposes minimal physical strain during repositioning. Its portability enables efficient handling by staff and facilitates flexible deployment across multiple procedure rooms, without necessitating permanent installation. Furthermore, the modular design of the W-Bi system allows customization to various procedural scenarios, accommodating differences in operator posture, patient positioning, and room layout. This adaptability is particularly advantageous in resource-constrained or multifunctional environments where procedural setups frequently vary and equipment is often shared. Collectively, these attributes highlight the W-Bi shielding system’s versatility and practicality in extending radiation protection to high-exposure anatomical regions—particularly the upper extremities—while preserving workflow efficiency and user comfort.

Dose rate measurements under various shielding conditions (shown in Figure 4) demonstrate that combining PPE with structural shielding effectively reduces occupational radiation exposure. Although lighter PPE provides less attenuation than heavier alternatives, this difference is minimized when structural shielding is used, suggesting that lighter PPE may be preferable for improved procedural convenience. At hand level—located near the X-ray source and difficult to protect with PPE—structural shielding such as lead-acrylic panels or W-Bi sheets significantly reduced exposure. These findings underscore the importance of integrating PPE with structural shielding to ensure comprehensive protection for both the bronchoscopist and assistant during bronchoscopy.

From a clinical implementation perspective, the proposed W-Bi shielding system is intended to integrate into existing bronchoscopy workflows. Under standard fluoroscopic settings, PPE serves as the primary layer of radiation protection, while W-Bi composite sheets or ceiling-mounted lead-acrylic barriers are applied as supplementary structural shielding. Because the W-Bi sheets are opaque, direct visualization of the patient may be partially restricted; however, this limitation can be effectively mitigated using a convex mirror, which reflects visible light but not ionizing radiation, thereby enabling clear observation beyond the shield.

Despite these favorable results under standard conditions, in the present phantom study, fluoroscopy parameters were fixed to represent commonly used bronchoscopy settings (65 kVp, 4.2 mA, pulsed fluoroscopy at 30 frames per second). Higher-output conditions—such as steep oblique angulation with automatic exposure control (AEC) escalation, markedly increased kVp/mA, prolonged continuous fluoroscopy, or CBCT-guided bronchoscopy—were not directly evaluated due to equipment limitations and image saturation observed under phantom conditions. Nevertheless, these extreme conditions are clinically relevant because they may increase scatter intensity and alter scatter energy spectra. Future work should therefore evaluate shielding robustness across an upper-bound test matrix that varies beam energy/output (e.g., higher kVp and/or mA with AEC on/off), fluoroscopy mode (pulsed low-frame-rate vs. continuous), C-arm angulation (LAO/RAO and cranial/caudal), and field size/collimation, and should include CBCT rotational protocols when applicable. Under such conditions, optimization strategies may include increasing effective thickness (e.g., an additional W-Bi layer) and/or expanding overlap coverage to minimize edge leakage, with performance assessed not only by mean dose reduction but also by worst-case “hotspot” measurements at the bronchoscopist and assistant position.

While this study focused on the W-Bi shielding system, comprehensive radiation safety requires a multifaceted approach. Personal dosimetry, for instance, enables continuous monitoring of occupational exposure, facilitating real-time assessment and long-term dose tracking for healthcare professionals (17). Procedural optimization—such as minimizing fluoroscopy time, employing beam collimation, and adjusting beam angles—can substantially reduce unnecessary radiation exposure (18). Equally important is the implementation of routine equipment maintenance and quality assurance protocols to prevent technical failures that might result in inadvertent dose escalation. Ongoing education and training for clinical staff further ensure adherence to radiation safety principles and promote a culture of informed practice (19). Additionally, the integration of advanced imaging technologies—such as pulsed fluoroscopy, low-dose acquisition protocols, and digital tomosynthesis—provides diagnostic capability with reduced radiation output and should be considered part of a broader protective strategy (2). These combined strategies enhance safety for patients and staff. Though beyond this study’s scope, they are essential for comprehensive radiation protection and should inform future research and policy.

This study demonstrates several key strengths that reinforce the validity, applicability, and practical relevance of its findings. First, the use of anthropomorphic phantoms and fixed fluoroscopic parameters (65 kVp, 4.2 mA, 30 fps) provided a controlled and reproducible experimental setting, allowing reliable dose measurements and clear attribution of attenuation effects to the shielding configurations. Second, the comprehensive measurement protocol evaluated radiation exposure at six anatomical locations, including four vertical height levels corresponding to the bronchoscopist’s body (50, 90, 130, and 170 cm) and two hand positions for both the bronchoscopist and assistant (130 and 90 cm). This approach enabled a more thorough assessment of occupational exposure—particularly in high-risk extremities that have often been underrepresented in previous studies. Third, the study included direct comparisons with certified ceiling-mounted lead-acrylic shielding systems and incorporated PPE evaluations, offering a holistic assessment of radiation protection strategies. Benchmarking the W-Bi shielding sheets against established devices further strengthens the credibility of performance claims. Fourth, the study provided data on the weight and shielding performance of various PPE configurations, enabling healthcare professionals to make informed choices based on individual preferences. Lastly, comprehensive cost evaluation and documentation of assembly procedures add practical value, making the proposed shielding system both scientifically robust and feasible for implementation in resource-limited clinical settings.

As this study utilized anthropomorphic phantoms, it reflects a static setup that does not fully capture the dynamic nature of clinical bronchoscopy. In actual procedures, frequent repositioning of the bronchoscopist and assistant—as well as variations in patient anatomy and fluoroscope angulation—can alter scatter radiation patterns and influence shielding performance. Moreover, phantom-based validation lacks key physiological features such as respiratory motion, soft tissue compliance, and realistic operator-patient interactions. Nonetheless, the primary objective of this study was not to quantify exact exposure levels, but to assess the feasibility of effective shielding strategies.

Concerns may arise regarding the material durability, safety, and maintenance of W-Bi shielding sheets. Previous studies of bismuth-based polymer composite shielding materials have demonstrated stable attenuation performance and structural integrity under repeated bending and extreme folding, without evidence of particulate detachment (20). In this study, the W-Bi sheets were used as suspended structural barriers rather than wearable components, thereby minimizing repetitive mechanical stress during routine clinical use. In accordance with International Commission on Radiological Protection (ICRP) recommendations, routine visual and tactile inspections should be performed at regular intervals.

Clinical validation of the proposed W-Bi shielding system within fluoroscopy-guided bronchoscopy settings is essential to evaluate its generalizability, seamless integration into routine clinical workflows, ergonomic compatibility, and long-term protective efficacy under dynamic procedural conditions. Future studies should incorporate user feedback from both bronchoscopist and assistants to optimize the system’s design and facilitate broader clinical adoption. As CBCT becomes increasingly integrated into bronchoscopy for enhanced imaging and navigation, the shielding system’s performance under CBCT-guided protocols warrants further exploration. Additionally, employing advanced dosimetry tools—particularly real-time personal dose monitoring—can offer granular, role-specific insights into radiation exposure, enabling the development of adaptive and optimized protection strategies responsive to evolving procedural demands.

Conclusions

In this phantom study, a triple-layer W-Bi composite shielding system demonstrated substantial reduction of scattered radiation during fluoroscopy-guided bronchoscopy, achieving attenuation levels comparable to those of a conventional ceiling-mounted lead-acrylic barrier at key anatomical sites, including the hands. The W-Bi system was associated with advantages in cost, portability, and suitability for space-constrained environments. These findings indicate that multilayer W-Bi shielding can serve as an effective supplemental structural shielding option when combined with standard PPE. Further clinical studies are required to validate its performance under dynamic procedural conditions and to define its role within comprehensive radiation protection strategies in interventional pulmonology.

Supplementary

The article’s supplementary files as

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Data Sharing Statement

Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-1763/dss

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DOI: 10.21037/jtd-2025-1763