Evaluation of Operator and Patient Doses after Irradiation with Handheld X-ray Devices

Abstract

This study aimed to evaluate radiation doses from handheld X-ray devices, specifically NOMAD Pro 2^TM (DvcN), Rextar X (DvcRX), and Diox 602 (DvcD), targeting operator and patient’s critical organs and tissues. Calibrated TLD-100H dosimeters were placed on a mannequin and phantom head, focusing on the eyes, thyroid, gonads, hands, and salivary glands. Using a TLD reader, absorbed equivalent doses post irradiation were assessed. Conventional systems yielded higher radiation doses than phosphor plates and digital systems. Notably, implementing protective measures resulted in significant (p < 0.05) dose reductions to the operator. Peak measurements without protection included: gonad 24.4 (DvcN) μGy; thyroid 30.5 (DvcN) μGy; right eye 31.9 (DvcN) μGy; left eye 27.9 (DvcN) μGy; right hand 111.6 (DvcRX) μGy; and left hand 71.7 (DvcD) μGy. Radiation dose reductions ranged from 11.49% to 93.25%, depending on the region and device. It is imperative to adhere to radiological protection protocols, particularly when employing handheld X-ray devices; optimally, these should be used with digital systems.

1. Introduction

Radiographic imaging is an essential part of a modern dental examination. It has been determined that the diagnostic benefits of ionizing radiation far outweigh the risks to the patient; therefore, radiological evaluation has become routine during clinical examination [1]. The first handheld X-ray devices were designed for military use in the early 1990s of the last century. Apart from military areas, it has found wide use in dentistry-related situations such as temporary health clinics, patients with reduced mobility, nursing homes, autopsies, morgues, and remote areas [2,3]. There has been a recent increase in the marketing of handheld portable X-ray devices for intraoral radiography in general dental clinics. Handheld X-ray units challenge the concept of a “controlled area” as they are held by the operator. The distance from the body varies depending on how the device is held. Although the device has an integrated shield, the handheld X-ray system raises concerns about increased operator exposure due to X-ray leakage and backscatter radiation as the operator is in direct contact with the X-ray source [4,5].

Exposure to X-ray radiation poses a tangible risk to biological systems due to its energy transfer capabilities. Such energy can induce structural damage to critical biomolecules like DNA within the exposed cells, thereby elevating the risk of detrimental effects, including carcinogenesis. With the increasing ubiquity of radiographic procedures utilizing X-ray technology, concerns over radiation-induced malignancies have grown. Radiation safety protocols aim to mitigate these risks by regulating the utilization of ionizing radiation sources, including X-rays [6,7,8]. Adherence to guidelines set forth by the International Commission on Radiological Protection (ICRP) ensures that both practitioners and the general public are not subjected to radiation levels exceeding internationally recognized safety thresholds. Consequently, quantifying the radiation dose absorbed by both patients and especially healthcare personnel exposed to X-rays is of paramount importance. Recent advancements in the field have led to a heightened focus on continually monitoring and setting estimated dose limits during public X-ray exposures. This approach aims to ensure the optimal safeguarding of both patients and medical staff [9,10].

This study aimed to determine the amount of radiation dose to which selected critical organs and tissues on personnel’s and patient’s bodies are exposed after irradiation with handheld X-ray devices.

2. Methods and Materials

In the present study, facilities from Ankara University Faculty of Dentistry and Atatürk University Faculty of Medicine’s Biophysics Department were employed. The focus was primarily on the handheld X-ray device, whose adoption has surged in recent times. The objective was to ascertain and compare the radiation exposure to selected organs and tissues in both the patient and the operator. For the purpose of this study, three distinct handheld X-ray devices were employed to irradiate the TLDs. Firstly, the NOMAD Pro 2^TM X-ray device (Aribex, Inc., Charlotte, NC, USA) was utilized. This device boasts specifications of 60 kVp, 2.5 mA power, 1.5 mm Al total filtration, and a 0.4 mm focal spot size. Weighing in at 2.5 kg, it has a cone length of 20 cm and requires a two-hand operation. Its digital timer display facilitates adjustments ranging from 0.02–1.00 s with 0.01 s increments. The second instrument was the Rextar X (Posdion Co., Seoul, Korea). Characterized by 70 kVp, 2 mA power, 1.5 mm Al total filtration, and 0.4 mm focal spot size, it weighs 1.6 kg and has a 6 mm circular diameter with a 4 cm cone length. Its ergonomic design is tailored for one-handed operation. Its timer, with a digital interface, can be modulated between 0.01 and 1.3 s, adjustable in 0.01 s segments. The third handheld in consideration was the Diox-602 X-ray device (DigiMed, Seoul, Korea). This device, presenting a specification of 60 kVp, 2 mA power, 1.6 mm Al total filtration, and 0.8 mm focal spot size, weighs 1.8 kg. Additionally, it has a 6 mm circular diameter and a 10 cm cone length, requiring bipedal operation. Its digital timer allows for adjustments ranging from 0.01 to 1.6 s in 0.01 s increments.

A soft and hard tissue equivalent maxillofacial phantom, ATOM^® Max Dental and Diagnostic Phantom, model 711 HN (CIRS Inc., Norfolk, VA, USA), was used to simulate the patient’s cranial structure. To ensure precision in positioning during the irradiation process, this phantom head was paired with a tripod, facilitating rotational adjustments across the x, y, and z axes. Representing the operator was a life-sized mannequin, standing approximately 185 cm (See Figure 1). All experimental procedures were meticulously orchestrated within the radiological laboratory of Ankara University’s Faculty of Dentistry. For the paramount safety of the personnel, irradiation was executed from behind a lead screen using a 2.5 m extended rod. Prior to initiating the experiments, thorough radiation safety checks were undertaken to ensure the assembly’s functionality and the adequacy of the radiation protection measures.

To measure the equivalent doses to the operator’s body and to estimate the doses as recorded by an occupational dosemeter, pre-calibrated thermoluminescent dosemeters (TLDs) (LiF: Mg, Cu, P, Harshaw Chemical, Solon, OH, USA) were placed on the mannequin and the phantom head (Figure 1 and Figure 2). TLD-100H dosimeters are in the form of a 4.5 mm diameter and 0.89 mm thick disk (chip) and are sensitive to small quantities of radiation down to 1 μGy.

Then, 100 TLD-100H dosimeters to be used in the experiments were heated at 225 °C for 10 min, and their stored energy was discharged. After numbering from 1 to 100, it was placed in a 3 mm thick plexiglass container. The dosimeters were irradiated with an X-ray source (periapical X-ray device/Belmont Phot-XII) whose radiation amount was determined using the RTI Black Piranha X-ray Meter device in the environment to receive a homogeneous 1000 μGy. During this irradiation, the amount of radiation reaching the vessel was measured as 1000 ± 10 μGy. Since the amount of radiation given to the dosimeters and the phototube current values read in the TLD-reader device are known, the conversion coefficients (Reader Calibration Factor—RCF) of the dosimeters used to convert the phototube current to the amount of absorbed radiation were calculated for the device. The energy of the dosimeters was discharged by heating them again at 225 °C for 10 min. The irradiation process of the dosimeters with an X-ray source whose radiation amount is known was repeated to find the element correction coefficients (ECC). The calibration process was completed by reading the dosimeters again in the appropriate set-up in the WinREMS software program on the TLD-reader device. After each irradiation, the dosimeters were read in the TLD reader after 12 h. The dosimeters, whose readings were made, were heated at 225 °C for 10 min and their absorbed energy was discharged. For the next irradiation, the dosimeters were placed on the phantom head and the devices in locked bags.

Organs and tissues that were selected for the determination of radiation dose within the scope of this study were:

• On the patient’s/phantom’s head;
• Thyroid (skin dose (SD));
• Right—left eyes;
• Right—left parotid glands (SD);
• Right—left submandibular glands (SD);
• Sublingual gland (SD).
• On personnel/mannequin;
• Gonads (SD);
• Thyroid (SD);
• Right—left eyes;
• Right—left hands.

TLDs were placed on the phantom head, mannequin, and devices in locked bags for irradiation, three in each area and four on the cone (Figure 2). Unlike the other two devices, since the NOMAD Pro 2TM device has a protective disc, TLDs were placed in front of and behind the protective disc, and irradiations were made. All irradiations were made by placing the same dosimeters in the same area during the experiments. In the experiments, irradiations were made for the following series of radiographs with each handheld X-ray device:

-

Conventional (Kodak Dental Carestream E-speed, Rochester, NY, USA) intraoral whole-mouth radiograph series (2 right and left bitewing, 7 maxillary periapical radiographs, 7 mandibular periapical radiographs; a total of 16 irradiations);

-

Phosphor plate (GXPS-500 PSP, Hatfield, PA, USA) intraoral whole mouth radiograph series;

-

RVG (CMOS) system (GENDEX GXS-700™, Hatfield, PA, USA) intraoral whole mouth radiograph series.

While the irradiations were performed, the NOMAD Pro 2^TM device; 60 kVp, 2.5 mA, Rextar X device; 70 kVp, 2 mA, Diox 602 device; and 60 kVp, 2 mA were used within those parameters, and times specified in

Table 1. Exposure times recommended by the manufacturers.

Irradiation Times (s) for Conventional Systems
	Anterior	Posterior	Bitewing
NOMAD Pro 2TM	0.30	0.38	0.40
Rextar X	0.30	0.38	0.40
Diox 602	0.30	0.38	0.40
Irradiation Times (s) for Photo Stimulable Phosphor Plate Systems
	Anterior	Posterior	Bitewing
NOMAD Pro 2TM	0.16	0.19	0.20
Rextar X	0.16	0.20	0.20
Diox 602	0.16	0.19	0.20
Irradiation Times (s) for RVG Systems
	Anterior	Posterior	Bitewing
NOMAD Pro 2TM	0.12	0.16	0.17
Rextar X	0.12	0.16	0.18
Diox 602	0.12	0.16	0.17

(recommended by the manufacturers).

With each device, images were obtained by irradiating at the recommended times in conventional (C), photo-stimulable phosphor plate (P), and RVG (R) systems. Image quality was not evaluated in our study. It was determined how the image would look when irradiated at the times recommended by the manufacturers (Figure 3).

Irradiations were performed on the personnel in the designated areas without protective measures and with protective measures.

For TLDs to give more accurate measurements, all irradiations were made three times (16 × 3), and the average of the values obtained was taken. In addition, these described operations were repeated three times to increase the number of observations.

A statistical evaluation of the effect of devices and protection factors on C, P, and R irradiations for each region was performed with two-way ANOVA. Multiple comparisons were examined with the Tukey test when differences in devices were found. Significance levels were accepted as 5% (p < 0.05) for two-way ANOVA and Tukey test.

3. Results

Background radiation of TLDs, which are not among other TLDs using mannequins and phantom heads in irradiation and are kept away from the irradiation area, was found to be 0.0132 Gy.

Irradiation measurements in the gonad, thyroid, right-eye, left-eye, right-hand, and left-hand regions using conventional (C), phosphor (P), and RVG (R) devices in NOMAD Pro 2^TM (N), Rextar X (RX) and Diox 602 (D) devices at dose levels, both protected and unprotected, were performed in triplicate, and the mean values for these results are summarized in

Table 2. Organ absorption dose averages (μGy) after irradiation (mannequin).

		NOMAD Pro 2TM			Rextar X			Diox 602
		C	P	R	C	P	R	C	P	R
Gonad	with protection	11.2	17.5	12.3	8.5	12.7	7.3	14.8	13.4	13.5
		26.8	24.4	18.3	14.2	13.2	19.7	25.3	21.8	22.5
Thyroid	with protection	11.3	15.5	12.4	10.2	9.5	7.8	15.1	17.5	15.7
		30.5	26.7	21.5	17.7	17.6	19.3	20.5	21.5	20.5
Right eye	with protection	11.5	9.8	13.1	9.6	7.8	7.8	16.4	17.3	13.2
		31.9	25.8	17.8	13.5	22.5	17.3	25.7	22.1	20.6
Left eye	with protection	11.3	11.6	13.5	10.6	11.2	12.6	12.9	14.4	13.5
		27.8	25.9	18.4	12.4	15.3	17.5	27.9	20.7	17.5
Right hand	with protection	11.5	14.9	12.4	11.5	8.8	7.8	18.5	18.6	17.6
		25.3	23.6	19.5	119.4	111.6	115.5	49.9	57.3	42.6
Left hand	with protection	11.6	12.5	16.7	8.9	10.2	8.6	21.3	16.5	18.4
		35.6	28.3	19.5	12.1	12.4	9.7	71.7	62.5	46.1

C: conventional, P: phosphor, R: RVG.

.

For the gonad region, the highest value was measured as 26.8 μGy in the unprotected C irradiation with NOMAD Pro 2^TM, and the lowest value was 7.3 μGy in the protected R irradiation with Rextar X. There is no statistically significant difference between devices N and D in C and P irradiations for the gonad region. Device RX produced a statistically lower radiation dose. There is no statistically significant difference between devices R and D in R irradiation of device N. Device RX produced a statistically lower radiation dose than device D (

Table 3. Pairwise comparisons for the regions (p < 0.05) (mannequin).

	Gonad	Thyroid	Right Eye	Left Eye	Right Hand	Left Hand
C	$N=D>RX$	$N=D, RX=D, N>RX$	$N=D>RX$	$N=D>RX$	$RX=D>N$	$D>N, N=RX$
P	$N=D>RX$	$N=D>RX$	$N=RX=D$	$N=D>RX$	$RX=D>N$	$D>N, N=RX$
R	$N=RX, N=D, D>RX$	$N=D>RX$	$D>N=RX$	$N=RX=D$	$RX=D>N$	$D>N, N=RX$

C: conventional, P: phosphor, R: RVG; NOMAD Pro 2^TM: N, REXTAR X: RX, DIOX 602: D.

).

On the mannequin, the highest value for the thyroid region was 30.5 μGy in the unprotected C irradiation with NOMAD Pro 2^TM, and the lowest value was 7.8 μGy in the protected R irradiation with Rextar X. There is no statistically significant difference between the devices RX and D in the C irradiation of the device N in the thyroid region. Device RX produced a statistically lower radiation dose than device D. While there was no statistically significant difference between devices N and D in P and R irradiation, device RX produced a statistically lower radiation dose (Table 3).

The highest value for the right eye area was 31.9 μGy in unprotected C irradiation with NOMAD Pro 2^TM, and the lowest value was 7.8 μGy in protected R irradiation with Rextar X. There is no statistically significant difference between devices N and D in C irradiation for the right eye area. Device RX produced a statistically lower radiation dose than devices N and D. There is no statistically significant difference between the three devices in P irradiation. There is no statistically significant difference between devices N and RX in R irradiation. Device D produced a statistically higher radiation dose (Table 3).

The highest value for the left eye area was 27.9 μGy in the unprotected C irradiation with Diox 602, and the lowest value was 10.6 μGy in the protected F irradiation with Rextar X. There is no statistically significant difference between devices N and D in C and P irradiation for the left eye region. Device RX produced a statistically lower radiation dose than devices N and D. There is no statistically significant difference between the three devices in R irradiation (Table 3).

The highest value for the right-hand region was 119.4 μGy in the unprotected C irradiation with Rextar X, and the lowest value was 7.8 μGy in the protected D irradiation with Rextar X. There is no statistically significant difference between devices RX and D in C, P and R irradiation for the right-hand region. Device N produced a statistically lower radiation dose than devices RX and D (Table 3).

The highest value for the left-hand region was 71.7 μGy in the unprotected C irradiation with Diox 602, and the lowest value was 8.6 μGy in the protected D irradiation with Rextar X. There is no statistically significant difference between devices N and RX in C, P and R irradiation for the left-hand region. Device D produced a statistically higher radiation dose than devices N and RX (Table 3).

A statistically significant difference was found between protected and unprotected irradiation at all dose levels in all regions.

The total doses of the organs on the phantom head selected for the study were recorded after irradiation. According to this, the highest total dose (153.2 μSv) was measured at the C irradiation in the Diox 602 device, while the lowest total dose (25.5 μSv) was measured at the R irradiation in the NOMAD Pro 2TM device. When the total dose results for the patient (phantom head) were evaluated in general, the highest values were found in conventional irradiations and the lowest in digital irradiations for all three devices (

Table 4. Total dose (μSv) of organs included in the study for all irradiations (phantom head).

	NOMAD Pro 2TM	Rextar X	Diox 602
C	113.4	146.4	153.2
P	88.1	92.9	60.3
R	25.5	58.4	42.1

C: conventional, P: phosphor, R: RVG.

).

The dose values measured from the cone ends of the devices included in the study are shown in

Table 5. Average dose values (μGy) measured from device cone tips after all irradiations.

	NOMAD Pro 2TM	Rextar X	Diox 602
C	292.65 (front) 28.65 (back)	258.796	210.108
P	133.956 (front) 25.976 (back)	155.958	134.51
R	113.284 (front) 12.134 (back)	115.177	84.305

C: conventional, P: Phosphor, R: RVG.

. According to this, the highest dose (292.6 μGy) was measured in the anterior region at the C irradiation in the NOMAD Pro 2^TM device, and the lowest dose (84.3 μGy) was measured at the R irradiation in the Diox 602 device.

The results of the measurements made in the hands, eyes, thyroid, and gonad regions by taking protective measures are shown in

Table 6. Reduced dose rates when protective measures are used for all regions (%).

	NOMAD Pro 2TM			Rextar X			Diox 602
	C	P	R	C	P	R	C	P	R
R. hand	54.23	36.8	36.18	89.7	92.62	93.25	62.94	67.43	58.67
L. hand	67.31	55.87	14.26	25.31	18.16	11.49	70.23	73.5	59.91
R. eye	64.43	62.08	26.74	28.44	65.21	54.98	20.64	21.07	48.61
L. eye	59.34	55.11	26.64	14.26	26.66	28.12	53.18	31.37	23.03
Thyroid	62.85	41.83	41.96	41.98	36.05	59.31	26.05	18.78	24.28
Gonads	54.05	34.46	32.80	40.03	30.84	62.89	31.98	47.03	40.11

C: conventional, P: phosphor, R: RVG.

. A statistically significant difference was found between protected and unprotected irradiation at all dose levels in all regions (p < 0.05).

In this study, irradiations were made with handheld X-ray devices at the recommended times for C, P, and R systems. The reduction rates of the phosphor plate and RVG systems in the patient’s dose compared to the conventional system are shown in

Table 7. Reduced dose rates of phosphor plate and digital system compared to conventional system (%).

	NOMAD Pro 2TM	Rextar X	Diox 602
P	22.38	36.55	60.64
R	77.45	60.09	72.58

P: phosphor, R: RVG.

.

4. Discussion

Radiological assessments play a pivotal role in the diagnostic and therapeutic decision-making processes within both the dental and medical fields. While the implications of protracted exposure to low-dose radiation remain a topic of ongoing research, emerging evidence suggests that the associated risks may be more pronounced than previously anticipated [11].

In the realm of clinical dentistry, radiographs are indispensable, forming an integral component of the daily diagnostic arsenal. Traditionally, dental X-ray machines have been either stationary (wall or floor mounted) or mobile (tripod based). However, advancements in technology have paved the way for the inception of handheld, portable, and rechargeable X-ray devices. Initially, these devices found application in sectors such as military medicine, dentistry, and humanitarian outreach. Subsequently, their utility extended to diverse fields like archaeology, forensic dentistry, veterinary sciences, and criminal forensics in disaster zones. A salient advantage of these handheld devices lies in their capacity to facilitate radiographic evaluations for patients with restricted mobility or those under general anesthesia, scenarios where traditional fixed or mobile X-ray units might be impracticable [2,5].

Typically, these devices are engineered to be held aloft, parallel to the ground, and at arm’s length from the user. However, their advent has ushered in a slew of queries pertaining to radiation safety, particularly concerning the operator’s exposure. Conventional stationary or mobile X-ray units necessitate that operators adhere to stringent safety protocols, which include maintaining a prescribed distance from the device and avoiding direct manual contact. Such protocols, ubiquitously termed being within the “controlled area”, are universally recognized and practiced, including within our jurisdiction. The primary intent behind these guidelines is to mitigate unwarranted radiation exposure to both operators and the broader public. Notably, the central apprehension surrounding handheld X-ray devices centers on the potential for undue radiation exposure to the operator [12].

Handheld X-ray devices, being directly operated by practitioners, challenge the conventional paradigm of the “controlled area”. To address this, manufacturers have incorporated shielding into the device’s design. Furthermore, select models are fortified with an acrylic shield imbued with lead, designed to counter backscatter radiation.

The existing literature pertaining to handheld portable X-ray devices indicates that when assessing the effective dose directly, both the patient and the operator are exposed to radiation levels beneath the recommended thresholds [12]. Nonetheless, the proximity of the device to the practitioner’s body can vary based on hand positioning and the specific manner in which the device is held. While these devices often feature inherent protective measures, with certain models boasting an additional acrylic protective shield, there remains an ongoing debate regarding the adequacy of these safeguards in negating undue radiation exposure to the practitioner. Consequently, it is advocated that operators employ personal dosimeters for added safety [13].

In the present study, radiation dose measurements from the practitioner operator and the patient were taken using the thermoluminescence dosimetry method using various mobile X-ray devices. The devices utilized for irradiations included the NOMAD Pro 2TM, Rextar X, and Diox 602, with TLD 100H employed for dose assessments. Given the 1 μGy sensitivity of the TLD 100H dosimeters, the precision of these measurements is purportedly high [14]. Palomo et al. [15] employed a single TLD for each region, subjecting it to a single irradiation, citing prior studies that demonstrated that the employed TLDs could adequately absorb radiation for a measurable outcome with just one irradiation [16,17]. However, irradiations expose a vast area to radiation, with the central beam differing in angle across various intraoral periapical film exposures. Pauwels et al. [18] have indicated that when fewer TLDs are utilized for repeated measurements, there can be disparities of up to 80% in organ and tissue dose outcomes [18]. As such, enhancing the number of TLDs undeniably augments measurement accuracy. For this study, three TLDs were positioned for each designated organ and tissue, with each irradiation being performed thrice to bolster measurement reliability. A mannequin, standing at 185 cm, was employed to simulate the practitioner, while a phantom head was used in lieu of an actual patient. All irradiations were conducted from a distance of 250 cm and executed from behind a protective screen (1 mm Pb).

In previous studies, the radiation dosages from handheld X-ray devices were consistently found to be below the recommended thresholds. A majority of these investigations were conducted in the USA, with others originating from Italy, Belgium, Korea, and England [2,3,5,12,19,20]. Notably, despite the presence of handheld X-ray devices in our national market, there has been an absence of related studies. As such, the current investigation holds significant relevance, serving as a pioneering effort within our nation to evaluate the risks associated with handheld X-ray devices.

Goren et al. [20] constructed their research framework based on the premise that an operator would conduct 300 irradiations weekly, cumulating to 15,000 irradiations annually. For dose assessment, the TLD-700 was employed, with the NOMAD^TM serving as the chosen portable X-ray device. TLDs were placed in the eye, thyroid, finger, and chest areas of the practitioner staff. The deduced annual radiation exposure for the operator was quantified as 18 mR for the chest region, 22.5 mR for the eyes, and 45 mR for the fingers. Given the contextual understanding that handheld X-ray devices are primarily utilized in specialized scenarios—including patients with limited mobility, elder care facilities, temporary healthcare clinics, forensic field investigations, remote locales, and military contexts—Goren et al. posited that these values remained comfortably within acceptable limits [20].

In the study undertaken by Hermsen et al. [21], radiation doses to both the operating practitioner and ancillary staff were gauged utilizing the ion chamber methodology, with the NOMADTM device deployed in disaster relief efforts post-Hurricane Katrina. In contrast to this, the current study employed a mannequin to simulate the position of the operator. Furthermore, to mitigate radiation exposure, irradiation was conducted from a distance of 250 cm, shielded by a 1 mm Pb screen.

A study by Danforth et al. [19] involved the strategic placement of three TLDs on staff at key anatomical locations: eyes, thyroid, chest, abdominal region, gonads, hands, and feet. Their findings indicated the highest radiation exposure to the reproductive organs and the most minimal exposure to the thyroid gland. The annualized whole-body dosage for the operator was ascertained to be 0.0453 mSv, which represents a mere 0.9% of the prescribed annual limit. Specifically, the reproductive organ exposure was 0.095 mSv, equating to 0.19% of the permissible annual dose [19]. Within the scope of the present study, standardization was achieved by consistently positioning the handheld X-ray device at the greatest possible distance from the operator’s body during all irradiation sessions. A distinctive feature of our study, diverging from that of Danforth et al., was the incorporation of three varying devices. For all these devices, peak radiation levels were observed in the hand region, while the nadir was identified in the gonadal region. This discrepancy in outcomes might be attributed to Danforth et al.’s operator holding the device proximal to the body, especially near the gonadal region, with their arms flexed at the elbows.

In the United States, portable X-ray devices have become increasingly prevalent, with an estimated thousands of units employed across sectors such as dentistry, veterinary science, the military, forensics, and research. Gray et al. [13] assessed the radiation dose from both portable and fixed X-ray machines during digital imaging. This comprehensive study spanned 18 dental clinics and utilized 661 personal dosimeters for measurements. The study’s temporal assessments were delineated on a weekly and monthly basis, leveraging Optically Stimulated Luminescence (OSL) dosimeters or Thermoluminescent Dosimeters (TLD) for data collection. Notably, devices such as the NOMAD™ and NOMAD Pro 2™ were employed as portable X-ray units. Dosimeters were positioned on personnel associated with fixed (wall-mounted) X-ray machines, while those operating portable units had dosimeters on both their bodies and hands. However, Gray et al. did not specify if the operator, during the irradiation with stationary X-ray devices, utilized a protective screen or shared the room with the patient. Further, there was no delineation regarding potential extraneous radiation exposure, such as sunlight or reflective radiation. Their results indicated that operators of fixed X-ray devices received a monthly body dosage of 27.3 μSv, in contrast to the 9.01 μSv recorded for portable device operators. Regarding hand exposure, out of 116 dosimeters, only 6 (5.2%) registered below the threshold value, suggesting negligible dosage [13]. In the present study, contrary to the methodology of Gray et al., it was taken as a reference that operators using fixed X-ray devices are not exposed to any radiation when they adhere to radiation protection rules (distance and protection considerations). Gray et al. reported elevated radiation values associated with fixed X-ray devices compared to their portable counterparts. This discrepancy might arise from operators’ non-adherence to established radiation protection guidelines. Additionally, the utilization of digital films in portable devices, compared with the application of conventional films in fixed machines, could further contribute to this variation. Despite these findings, the recorded doses remained within the safety thresholds established by the National Council on Radiation Protection and Measurement (NCRP) [22]. Notably, Gray et al. did not underscore the significant monthly hand dose of 208 μSv. Similarly, our study indicated that the highest radiation doses were consistently observed in the hands (Table 3).

The highest value for the right-hand region was 119.4 μGy in the unprotected P irradiation in the Rextar X device, and the lowest value was 11.5 μGy in the protected C irradiation in the NOMAD Pro 2^TM device. Obtaining quite different results after the measurements made on the devices can be explained by the fact that the primary protectors constituting the internal structure of the devices are different, and the fact that the devices differ from each other in terms of shape causes different holding positions. Due to these different grips (Rextar X is used with one hand), the lowest value in the left hand was measured as 8.6 μGy in protected R irradiation in the Rextar X device. The highest value in the left-hand region was measured as 71.7 μGy in the unprotected C irradiation of the Diox 602 device.

In the study of Cho et al. [23], the focus was on the frequently utilized DX3000 and Rextar brand portable X-ray devices in Korea, with dose measurements carried out using the ion chamber method. The areas evaluated for radiation exposure on the operator included the hands, waist, and chest regions. Various configurations were tested: both long and short cones, with and without acrylic shielding, and with and without lead gloves. The results indicated that employing long cones reduced radiation doses by 48–52%, wearing lead gloves led to a 26–31% reduction, and the inclusion of an acrylic protective shield resulted in a 23–32% dose reduction compared to short cone usage. In our analysis, the differential efficacy of lead gloves, compared to Cho et al.’s findings, may be attributed to varying lead content and the use of distinct glove brands. Table 6 presents the measurement outcomes from the hands, eyes, thyroid, and gonad regions when protective measures were implemented. While Cho et al. conducted measurements both with and without a protective disc, in the current study, TLDs were positioned both in front and behind this disc. Particularly for the NOMAD Pro 2TM device, where the protective disk is a fixed feature, our irradiation studies were conducted in this manner. It was found that the radiation dose in the region just behind the protective disc was reduced by approximately 85 ± 5%.

Makdissi et al. [12] used the NOMAD Pro 2^TM device and the operator held the handheld X-ray device in 3 different positions and irradiated it. In the thyroid region, the highest recorded exposure was for Test 1 (0.0043 mGy), but fewer values were observed in Test 2 (0.0023 mGy) and Test 3 (0.0013 mGy) measurements. The index finger (representative trigger finger) of the right hand recorded a similar exposure for Test 1 (0.0120 mGy) and Test 2 (0.0117 mGy), but a lower exposure for Test 3 (0.0070 mGy). The palm of the left hand recorded a variable amount of exposure across all tests; the highest recorded exposure was in Test 3 (0.0310 mGy).

Higher values were observed in the lumbar region in Test 3 (0.0110 mGy) and, subsequently, in Test 1 (0.0057 mGy). In the feet region, 0.0047 mGy and 0.0030 mGy were recorded in Test 1 and Test 2, respectively. In the present study, the highest value (0.0305 mGy) in the thyroid region was measured in C irradiations in the NOMAD Pro 2^TM device. The values observed in P and R irradiations are 0.0267 mGy and 0.0215, respectively. In Rextar X and Diox 602 devices, it is 0.0182 mGy and 0.0208 mGy on average, respectively. In the right-hand region, the highest value was measured as 0.0253 mGy in C irradiations in the NOMAD Pro 2^TM device. The values observed in P and R irradiations are 0.0236 mGy and 0.0195 mGy, respectively. In Rextar X and Diox devices, it is 0.1155 mGy and 0.0499 mGy on average, respectively. The difference observed between the devices in the hands area in our study may be due to the differences in device internal structures, device designs, and materials and protectors used in device production.

In a study by Rottke et al. [24], the scatter radiation emanating from the handheld X-ray device, NOMAD Pro 2^TM, and the subsequent exposure risk to the operator were examined utilizing the ionization chamber technique. Their findings posited that the device does not amplify the risk to the operator when operated within the guidelines set by the manufacturer. In addition, they reported that the concept of “controlled area” is smaller than the currently accepted version.

Iwawaki et al. [25] focused on assessing the radiation doses received by the fingers and lens when employing various handheld X-ray devices. Their data underscored the efficacy of protective shields in diminishing finger dose exposure and emphasized that increased distance correspondingly reduced the lens dose.

Similarly, Moshfeghi et al. [26] evaluated the radiation doses received in specific regions—fingers, hands, interpupillary distance, sternum, and genital area—by radiology personnel during the operation of a handheld X-ray device. Their findings indicated that the dose exposure fell within the thresholds recommended by the ICRP [0.16 (0.12–0.23) per hour or 1.28 (0.96–1.84) per day]. These results align with the outcomes of the current research. However, a distinct methodological difference existed: instead of employing a mannequin, as in the current study, Moshfeghi et al. [26] conducted their irradiations with personnel equipped with lead shields.

It is pertinent to note that a limitation of the present research was the consistent distance maintained between the mannequin and the device. In practical settings, operators might employ varied positions during X-ray operations, potentially altering the radiation dose to different organs. Future research endeavors could incorporate this variability by conducting evaluations across a range of positions.

5. Conclusions

In the present study, dose measurements were performed using handheld X-ray devices NOMAD Pro 2^TM, Rextar X, and Diox 602, and the TLD method.

According to the findings, handheld X-ray devices should be operated by trained personnel and are particularly suited for use in settings such as remote areas, military zones, and temporary healthcare facilities. Protective measures must be rigorously followed when using these devices, with preference given to equipment featuring protective discs and elongated cones. Further organ dosimetry studies are needed to fully understand the implications and risks associated with their use.