Journal of Indian Academy of Oral Medicine and Radiology

REVIEW ARTICLE
Year
: 2018  |  Volume : 30  |  Issue : 2  |  Page : 153--157

Hand-held X-ray device: A review


D N S V Ramesh, Mahalakshmi Wale, R Thriveni, Amit Byatnal 
 Department of Oral Medicine and Radiology, AME's Dental College and Hospital, Raichur, Karnataka, India

Correspondence Address:
Dr. Mahalakshmi Wale
Department of Oral Medicine and Radiology, AME's Dental College and Hospital, Raichur, Karnataka
India

Abstract

This is an era of digital revolution where the world is shifting from analogue to digital electronics. This revolution has led to the invention miniaturization of devices and one such invention is hand-held X-ray devices. With the introduction of new technology in dental radiology, there is a need to change or update old guidelines that many states use to regulate the use of ionizing radiation. Currently, there are voluntary guidelines promulgated by the NCRP for dental radiation protection. Many states use the Conference of Radiation Control Program Directors Suggested State Regulations for the Control of Radiation to regulate the use of X-ray equipment. Hand-held portable X-ray devices are increasingly used for intraoral radiography. This development introduced new challenges to operator and patient safety, for which new or revised risk assessments must be made and acted upon prior to use.



How to cite this article:
V Ramesh D N, Wale M, Thriveni R, Byatnal A. Hand-held X-ray device: A review.J Indian Acad Oral Med Radiol 2018;30:153-157


How to cite this URL:
V Ramesh D N, Wale M, Thriveni R, Byatnal A. Hand-held X-ray device: A review. J Indian Acad Oral Med Radiol [serial online] 2018 [cited 2021 Jul 26 ];30:153-157
Available from: https://www.jiaomr.in/text.asp?2018/30/2/153/236727


Full Text



 Introduction



An important part of a modern dental examination is radiographic imaging. While there are risks to the use of ionizing radiation, the diagnostic benefits have been determined to outweigh the risks; thus, the procedures have now become routine during regular exams.[1]

The first hand-held portable dental X-ray devices date back to the early 90s of the past century; those devices were intended to be used in the military field. An increase in the marketing of hand-held portable X-ray devices for intraoral radiography in general dental facilities has been recently observed and hand-held portable X-ray devices are valuable online only at present [Figure 1].[2]{Figure 1}

Types of hand-held X-ray devices

NOMADNon-FDA–cleared device [Figure 2] and [Figure 3]Tube-based X-ray fluorescence (XRF).{Figure 2}{Figure 3}

Since the introduction of hand-held X-ray units in dentistry, a few inexpensive devices have emerged that lack the necessary safety measures and failed to meet the U.S. Food and Drug Administration standards.[3]

Hand-held X-ray units challenge the concept of a restricted access “controlled area” as they are held by the operator. Although an integral lead shield is provided, the distance from the body is variable and depends on how the device is held.[4]

A new hand-held battery-operated portable X-ray system was tested for possible leakage radiation through the existing heavy metal compounds surrounding the X ray tube, backscatter radiation through the lead-filled acrylic shield attached at the end of the exit tube, and patient exposure.[5]

Some uses permitted with the hand-held unit would be

Use in nursing homesHome health careSpecial needs patients (individuals who require assistance for disabilities such as medical, mental, or psychological)Sedated patients who are unable to cooperate with the positional requirements of the radiographForensic workIn outreach programs like dental camps.

The current hand-held portable X-ray devices resemble a photographic camera or have a “shotgun” design. The devices are used as a replacement for wall-mounted or semi mobile X-ray devices (on a tripod or mobile support) and differ in two major characteristics from those:

The operator holds the hand-held portable X-ray devices during exposure of the patient, so the operator cannot stand back of radiation protection shields, and therefore, dedicated means of (scatter) radiation protection need to be providedThe newer handheld devices have typically a lower output dose rate (set by current, waveform, filtration and cone length) than the traditional wall-mounted direct current units.[2]

Hand-held portable X-ray devices should only be used in specific cases where it is impractical or impossible to transfer the patient to a fixed mounted X-ray installation and use of mobile devices are not practicable, such as in:

Operation theatres where no fixed mounted X-ray unit is available and the patient is under general anesthesia or sedation. The first choice in this case should be a semi-mobile deviceEmergency rooms, surgical suites, patient rooms, or other hospital facilities for immobile patients. The first choice in this case should be a semi-mobile deviceNursing homes, residential care facilities, or homes for persons with disabilities, which compromise mobility or their general health and who are thus unable to attend a healthcare facility. In this case, the follow-up treatment should be considered before justification of the X-ray procedure is made. If follow-up treatment is not available at the site, the patient might need to be moved to a healthcare facility, and X-ray imaging can be performed at the healthcare facilityDetention centre facilities where persons are physically confined and cannot easily be moved or transferred.

Most accepted and cleared by FDA is NOMADTM.

Hand-held X-ray machine offers portability in X-ray technology, featuring cordless operation, rechargeable 14.4-V nickel–cadmium battery packs, and provides more than 100–700 exposures on a single charge. It weighs 8 pounds, has internal lead shielding, and an external lead–acrylic backscatter shield. There is an automatic shut off and “Enable” feature that minimizes the risk of inadvertent exposure.

The hand-held X-ray device uses direct current, operates at a fixed 60 kV, 2.3 mA, and has a 0.4 mm focal spot with a 20 cm source-to-skin distance.[5]

Exposure parameters for hand held X-ray device [Table 1].[1]{Table 1}

Whole body radiation exposure limit for hand held X-ray device [Table 2].[6]{Table 2}

The high-voltage power supply is a high-frequency DC unit, which reduces the dose to the patient. Second, the X-ray tube is surrounded by compounds of heavy metals to reduce the leakage radiation from the tube.

British Standard BS EN 60601-2-65:2013 sets a limit on tube head leakage of 0.25 mGy an hour averaged over 100 cm 2 at a distance of 1 m, with an added note that, for hand-held equipment, the protection of the operator is subject to the manufacturer's risk assessment process.

The ICRP-60 recommends an annual dose limit of 20 mSv (averaged over 5 years) owing to the occupational exposure of the whole body, 500 mSv for hand dose and 150 mSv for the eye lenses.

The estimated annual effective dose and the annual equivalent dose to the operator's whole body and hands from these devices, when used correctly, were well below 0.25 mSv and 10 mSv, respectively.[7]

The beam limiting device (exit cone) is lined with Pb. This would not normally be required in a dental unit as the exit cone is defined by Pb apertures closer to the tube. However, in our case, backscattered radiation from the patient could travel through the exit cone and impinge on the operators' hand. This backscattered radiation is absorbed in the lead-lined cone.

Backscattered radiation is also absorbed in a Pb-filled acrylic shield attached at the end of the exit cone. This shield has a Pb-equivalent of 0.5 mm thickness, and protects the operators' torso, hands, face, and gonads from backscattered radiation from the patient's face and teeth [Figure 1] and [Figure 3].[1]

Because of its innovative internal shielding, hand-held X-ray machine is safe for the operator to use. The X-ray tube and collimator are enclosed in a proprietary compound that blocks radiation leakage. The leaded acrylic shield at the front of the device provides the operator with a “zone of protection” from backscatter radiation during the actual exposure [Figure 4].[6]{Figure 4}

Lead apron applicable in hand-held X-ray: The operator to stand at least 1.5 m away from the tube head and patient; lead apron of at least 0.25 mm lead equivalency is needed.[8]

Radiation protection of the patient

The main consideration in any radiographic procedure involving live patients is to reduce the dose to the patient as much as possible while still achieving the diagnostic goals. Hand-held X-ray device is designed to operate with factors that help to maintain the safe operating region:

High-frequency, constant potential has been shown to reduce patient dose by up to 1/3 per image.

System is optimized for digital sensors at 60 kV. Digital sensors reduce the dose per image by 1/4th to 1/10th compared with conventional filmBeam is limited to 6 cm diameter, rather than the allowed 7 cm. This smaller irradiation area reduces the patient dose by 25% without significantly compromising the beam aiming capability.[5]

Radiation protection of the operator

Operators should always wear personal protective equipment (PPE) while using the hand-held equipment to be shielded from backscatter radiation. Both an apron (with 0.5 mm lead equivalent) and thyroid collar are recommended. This X-ray unit must only be operated by trained personnel in a controlled settingWithin such a setting, ensure that only the patient is in the direct beam of the X-ray, and that any ancillary personnel are a minimum of 3 m (approximately 9 feet) away from the patient. If it is necessary for any ancillary personnel to be closer than 3 m, these personnel should stay out of the direct beam.[6]

General population

A radiation risk assessment should always be available for the location in which the handheld portable X-ray device is used. The radiation risk assessment should include a minimum clearance distance (“controlled area”) around the X-ray device and shielding requirements if applicable.[2]

Image quality

The same image quality requirements apply to handheld portable X-ray devices as do to fixed intraoral X-ray units.

0.4 mm focal spot produces sharp, high resolution images. No blur from hand movementHigh-frequency, 60-kV DC X-ray generator produces clear images while reducing patient dose.

In the study of Pittayapat et al. it was concluded that handheld portable X-ray devices produce satisfactory image quality for use in forensic odontology.

Therefore, only films with speeds designated as E or ideally F-speed or faster or digital image receptors (sensors or phosphor plates) should be used to minimize the required dose.

It has been clinically shown that handheld device produces diagnostic-quality X-rays and will work equally well with both film and digital imaging media.

Hand held device provides all the benefits of DC performance: highest quality images and lowest patient dosage

Hand held X-ray devices as high-frequency, 60 kv DC X-ray generator provides constant radiation output [Figure 5].[7]{Figure 5}

Duty cycle

The hand-held device is also designed to avoid damage from overheating. The minimum duty cycle rating for maximum exposure (the relationship between duration and frequency of exposures taken during a rolling 60 second period) is 1:60. The following table shows examples of optimal use:

[INLINE:1]

AC and DC current

Half wave rectification. The rectifier blocks current flow in the inverse half of the electrical cycle resulting in the flow of the current in one direction only and this is known as half wave rectification as well as self-rectification. This is currently found in most dental X-ray machines. Larger X-ray machine use full wave rectification.

Recently, some X-ray manufacturers have used amplifiers to increase the number of cycles and are claiming that they are obtaining a continuous direct current resulting in a current that has higher energy at the same voltage [Figure 6].[9]{Figure 6}

Product review of NOMAD Tm

The NOMAD Dental X-ray System has been tested and found to comply with the limits of electromagnetic compatibility standards for medical devices, which provide reasonable protection against harmful interference in a typical medical/dental setting.

The NOMAD MD X-ray system is intended for use in the electromagnetic environment as specified. The NOMAD MD uses RF energy only for its internal function. In addition, the housing includes conductive shielding; therefore, while portable and mobile RF communications equipment can affect other medical electrical equipment, the RF emissions of the NOMAD are very low and are not likely to cause any interference in nearby electronic equipment.[10]

Security, storage, and transportation

The optimal storage location is cool, dry, and away from direct sunlight.

Battery

The charging for 30 to 45 min can be used for 8 hours. Color red indicates low battery.

Green indicates start and yellow X-rays exposures.

Advantages of hand-held radiography for dental professionals

Operator can stay with the patient during X-ray proceduresTake radiographs twice as fast as with conventional X-ray systemsReduce number of retakes by up to 50%Move hand-held X-ray devices from room to room, eliminating the need for multiple unitsCarry anywhere – ideal for hospital, home-health, humanitarian, and out-of-office useThe any high degree of flexibility makes it easy to take exposures while the patient is reclined, lying completely on their back, or sitting uprightThere are less chances of cone-cut and others errors in taking X-raysNo need to follow accurate angulations. usually 90° or perpendicular to the film or sensor is maintainedLight weight, cordless, easily transportableNo awkward arms to manipulate; no driftNo need for special stands, cables, remotesHundreds of diagnostic quality images from a single battery chargeWorks with sensors, film, phosphor platesExceptionally valuable in dental surgery suitesPerfect for use with sedated patients, children, geriatric or special needsIdeal for general dentistry, humanitarian work, clinics, mobile, home health, hospitalsIt is rechargeable one so no need of current to operate the device.

Disadvantages of hand-held radiography for dental professionals

The main drawback is that ALARA principal is not followedThe device must be angled and the operator cannot be completely within the protection zoneCompulsory lead apron is necessarily should be worn by the operatorSome time the radiofrequency which is used to produce X-ray leads disturbs other operating machinesAn experienced operator is needed.

 Conclusion



The hand-held device is easy to set up and use. It meets radiation safety standards. It has potential for use in forensic dentistry, humanitarian missions and nursing homes, and for disabled patients. This is beneficial for the operator and the patient and is less time consuming. Many more studies have to be conducted to know more about the hand-held X-ray devices.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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