Windy Rothmund, MSDH, RDH
Intraoral radiography is a long-standing and essential tool used to support the diagnosis, treatment, and management of dental conditions. When Wilhelm Roentgen captured the first x-ray back in 1895, he probably never imagined the digitial revolution that would lead to today’s high-tech wall-mounted units and handheld x-ray devices. Both wall-mounted units and handheld devices are sources of x-rays used to produce dental images with film, phosphor plates, or digital sensors.1 Conventional intraoral x-ray equipment is designed to be fixed to the wall or ceiling, with the exposure button located behind a protective barrier to ensure the operator receives no exposure to x-rays. Handheld x-ray devices, developed in the early 1990s for military medicine and humanitarian missions, have increased in popularity over the past few years in dental practices, challenging the concept of a “controlled area.”2,3
When using conventional wall-mounted units, the operator has to leave the room and stand behind a shielded wall during exposure. Today, handheld battery-powered devices make it possible to stay in the room and hold the x-ray device. Various handheld devices are available on the market offering advantages and disadvantages over wall-mounted units. They come in two forms, a pistol design resembling a hairdryer, operated by a trigger on the handle, and a camera-like design operated by a push button.1
Basic components of a handheld device include an x-ray tube assembly, irradiation switch on the body, and a protective shield at the end of the cone to reduce backscatter radiation to the operator.1 Handheld devices are an appealing solution for dental practices wanting to avoid the cost of purchasing wall-mounted units for every operatory. However, before making the decision to go “off the wall” and invest in a handheld device, it’s critical to look at the entire picture by evaluating the benefits and pitfalls of these new devices.
Benefits of handheld devices
Handheld x-ray devices offer advantages compared to traditional wall-mounted units, including portability and flexibility in patient care. The patient may feel less intimidated about x-rays if the operator stays in the room instead of running out to stand behind a wall during exposure. The ability to stay in the room makes it ideal for use with any patient who has difficulty with x-rays, including pediatric, geriatric, special needs, or fearful patients.4 In addition, staying in the room may reduce the number of retakes caused by patient movement and improve efficiency and workflow. In fact, the time needed to take radiographs is often reduced by half, saving approximately 120 hours annually.4 The freedom to position portable devices at any angle makes it possible to take x-rays while the patient is reclined or sitting upright.4
In terms of economics, one handheld device can service up to four operatories, eliminating the need for multiple wall-mounted units.4 There is no need for installation, special cabinetry that takes up space, reinforced walls, or electrical work. In addition to saving on acquisition costs, maintenance costs associated with multiple wall-mounted units are eliminated. Moreover, bulky wall-mounted units have awkward arms to manipulate, which often drift during exposure or if the patient moves unexpectedly.
The most accepted handheld x-ray device cleared by the US Food and Drug Administration (FDA) is the pistol design, such as the KaVo Nomad Pro 2.2 Weighing about six pounds, this cordless, lightweight device is easily transportable between operatories.4 The ergonomic design makes the shape and weight dispersion more stable in the operator’s palm.4 The KaVo Nomad Pro 2 model utilizes a 0.4 mm focal spot that produces sharp, high-resolution exposures, and a 60 kV DC x-ray generator that helps to ensure clear images and can reduce the patient’s radiation dose.2 Hundreds of high quality diagnostic images can be taken on a single battery charge—up to 600 shots.4 Images from newer handheld units are often superior to older wall-mounted units.1
Pitfalls of handheld devices
Despite the attractive benefits, there are disadvantages that come with handheld devices. First, there is the potential for the device to be knocked to the ground or dropped as it is being carried from operatory to operatory or when trying to adjust an x-ray. If the device becomes damaged it will have to be sent out for repair, leaving the office with no x-ray source to take radiographs. (Notably, the Nomad warranty includes overnight shipment of a loaner device.)
Second is the fatigue that may result from the entire weight of the unit being held and supported by the operator; a handheld device weighing between five and eight pounds is the equivalent of carrying a large bag of flour.5 The degree of fatigue can be lessened if the device is designed more ergonomically. Productivity may be affected if the operator has to put the unit down to make adjustments. Some designs, such as the Nomad, are designed to be cradled and thus should normally not need to be set down.
Also, a depleted battery may disrupt operations if the operator grabs it while the patient is in the chair and finds it does not work.6 Therefore, someone must be in charge of monitoring the battery and maintaining a charged backup battery pack. There is also potential for image quality to be affected by reduced or inconsistent radiation output as the battery charge reduces.6
Frustration may be an issue if one device is being shared between many operators and the operator has to locate the unit and wait for it to be available. Next, there is the issue of disinfection. Handheld devices cannot be sterilized; however, a wipe down with a disinfectant cloth between patients or at another routine interval is needed to adhere to infection control standards. With the power off and the handset attached, a nonacetone cleaner containing less than 20% alcohol may be used to avoid damaging the housing and bezel area.4 The risk of cross contamination may also be reduced by placing a disposable plastic barrier over the device.4
Another pitfall is the security procedures that must be in place to prevent unauthorized use or theft.7 Anytime the device is not in the operator’s direct supervision, it must be placed in a secure cabinet, storage room, or work area.7 When the dental office is closed, the device must be stored out of sight with the battery pack removed and, if possible, stored separately.7 All users of the handheld device require proof of training regarding safe use, risks involved, and radiation protection measures.6
One of the biggest challenges associated with handheld devices is keeping the operator within the protection zone of the backscatter shield (figure 1). This is achieved by maintaining the device perpendicular to the sensor to keep the x-ray beam on the horizontal plane.3 The position of the handheld x-ray device relative to the operator has a significant effect on the overall radiation exposure received by the operator.3
The height and inclination of the dental chair should be adjusted so that the x-ray tube is one inch away from the patient’s face.4 The operator should avoid adjusting his or her position to suit the patient, as this may result in part of the operator’s body (head or feet) not being in the protection zone.4 Rather than angling the device to take an x-ray, the operator must have the patient tilt his or her head or change the position of the chair, which may be difficult or uncomfortable for the patient. If the device is angled, the operator must wear a lead apron of not less than 0.25 mm lead equivalent for protection against scatter radiation.4 Because the cone of the handheld unit must be placed as close to the patient as possible without touching him or her, aiming devices with a shorter arm must be used on the image receptor holder.6 The arm of longer image receptor holders may obstruct the backscatter shield and increase the distance between the x-ray source and the patient, thereby increasing the area that is irradiated and the radiation required to take a quality image.6
Finally, if the handheld device is used in an open area, a controlled perimeter must be established. A controlled perimeter assures dental personnel do not stand in the path of the x-ray beam, remain behind a protective barrier, or stand at least six feet away from the patient and between 90 to 135 degrees to the direction of the primary beam during exposure.4
Possible health risks
Since the 1950s, radiation safety standards have followed the principles of ALARA (as low as reasonably achievable) to maintain radiation exposure well below the maximum permissible dose of 1 millisievert (mSv) annually.8 Commitment to ALARA principles is important because the long-term effects of low-dose radiation are unknown.8 In fact, ALARA is required by law, mandated by the United States Nuclear Regulatory Commission Title 10 Section 20.1003, and applicable to stationary, mobile, and handheld x-rays units.9
Although not legally binding, recommendations by the National Council on Radiation Protection and Measurements (NCRP), FDA, and the American Dental Association (ADA) help reduce radiation risks for operators and patients.7,10 With both traditional wall-mounted units and handheld devices, the operator assumes responsibility for following state and federal safety regulations.7 This includes poor technique resulting in retakes, poorly serviced or damaged equipment, or danger to themselves or others.4
Time has shown the diagnostic benefits of x-rays outweigh the risks, making them a routine dental assessment, but what about newer handheld devices? With the introduction of handheld devices in dental practices, there is a need to evaluate if additional risks to the operator or patient exist when compared to traditional wall-mounted units. New safety challenges are introduced that may violate the principles of ALARA, such as angling the device or not maintaining a controlled perimeter. Also, because of the close proximity to the operator, handheld x-ray devices pose increased operator exposure concerns due to leakage radiation and backscatter radiation.11 The operator using the device daily for routine care is at highest risk of long-term exposure. Also, longer exposure times are needed for handheld devices operating with a lower tube current (below 60 kV) than traditional wall-mounted units.2
Keeping this in mind, the inverse square law tells us that the effective dose of radiation 1 foot from a radiation source is 100 times greater than at 10 feet. Because of these concerns, state and federal agencies regulate handheld devices closely. Each state makes its own decisions about radiation monitoring programs, use of a lead apron by the operator, and which devices may be used, even if they have been cleared by the FDA.2,5
Numerous studies have shown handheld devices are safe for clinical use and do not present a significantly greater radiation risk than traditional wall-mounted units, leading to FDA approval of several handheld units.3 Conversely, a 2019 study found handheld x-ray units have the potential to increase radiation risk to the operator when compared to wall-units.1 In fact, the study found that scatter radiation dose from handheld units was above the expected dose for conventional wall-mounted units of 0.1 mSv.1 Based on ALARA principles, this recent study suggests using handheld devices only when use of a handheld device on a stand or wall-mounted unit is not feasible.1
Furthermore, the NCRP does not recommend the use of handheld x-ray devices when wall-mounted units are available.8 It is the employer’s responsibility to purchase a handheld device that is FDA and state approved in order to provide safe working conditions for dental personnel.7Even if there is an increase in exposure when using wall-mounted units, radiation levels associated with handheld devices do not exceed regulation limits if an FDA-certified device is used.3 Buyers should be aware that inexpensive devices marketed online lack the necessary safety measures and fail to meet FDA standards.2 Operators should ensure the device is cleared by the FDA by checking for a certification label, warning label, and identification tag permanently attached on the housing, written in the English language.12 Devices not approved by the FDA pose major safety hazards, including high doses of radiation to patients and operators, lack of shielding, low kV, and inadequate collimation.12
In the United States, there are no standard federal regulations regarding handheld x-ray devices. Therefore, individual states vary in their approval and requirements for handheld x-ray devices, including storage, use of protective apron, and radiation monitoring. It is important to note that states approve handheld units on a case-by-case basis, and not all FDA approved machines have been approved by every state. Regulations specify a minimum of E or F speed film or a digital sensor should be used.4 While the use of lead aprons with thyroid collars is not required for patients when optimal rectangular collimation is implemented, according to the NCRP and the ADA, their use is advised with handheld devices due to round collimation.7,8 The FDA recommends that the lead-embedded acrylic shield is in place, has minimum specifications of 0.25 mm lead equivalent, is 15.2 cm in diameter, and capable of being positioned no farther than 1 cm from the end of the cone to sufficiently block backscatter radiation and create a protective zone for the operator.6
The face of intraoral radiography is changing as handheld x-ray devices gain popularity in dental practices across the country. Whether a pistol design or camera-like design is utilized, there are advantages and disadvantages compared to conventional wall-mounted x-ray units. Advantages include portability, patient satisfaction, fewer retakes, and lower acquisition cost. Disadvantages include operator fatigue due to the weight of the device, no longer having free hands to adjust x-rays, having to share with multiple users, keeping the battery pack charged, disinfection, security concerns, and keeping the x-ray beam in the horizontal plane to avoid excessive radiation exposure. Even though some studies show FDA-approved devices may expose the operator to more radiation than wall-mounted units, radiation levels are still well below the maximum permissible dose. Operators must receive proper training before using a handheld device and be aware of requirements specific to their state, including which devices are cleared for use.
1. Smith R, Tremblay R, Wardlaw GW. Evaluation of stray radiation to the operator for five hand-held dental x-ray devices. Dentomaxillofac Radiol. 2019;48(5):20180301. doi:10.1259/dmfr.20180301.
2. Ramesh DNSV, Wale M, Thriveni R, Byatnal A. Hand-held X-ray device: A review. J Indian Acad Oral Med Radiol. 2018;30(2):153-157.
3. Makdissi J, Pawar RR, Johnson B, Chong BS. The effects of device position on operator’s radiation dose when using a handheld portable x-ray device. Dentomaxillofac Radiol. 2016;45(3):20150245. doi:10.1259/dmfr.20150245. Epub 2016 Jan 14.
4. Operator manual: NOMAD Pro 2 handheld x-ray system for intraoral radiographic imaging. http://q9bgh9q08416907ck9fxol3z-wpengine.netdna-ssl.com/wp-content/uploads/ARU-07P2-NOMAD-Pro-2-Manual.pdf. Published 2013.
5. Six surprising pitfalls of handheld dental x-rays that can cost money. ImageWorks website. https://www.imageworkscorporation.com/five-little-known-facts-about-handheld-dental-x-rays-that-can-cost-your-practice-money/.
6. Berkhout WER, Suomalainen A, Brullmann D, Jacobs R, Horner K, Stamatakis HC. Justification and good practice in using handheld portable dental x-ray equipment: A position paper prepared by the European Academy of Dentomaxillofacial Radiology (EADMFR). Dentomaxillofac Radiol. 2015;44(6):20140343. doi:10.1259/dmfr.20140343.
7. American Dental Association Council on Scientific Affairs, US Food & Drug Administration. Dental Radiographic Examinations: Recommendations for patient selection and limiting radiation exposure. https://www.ada.org/~/media/ADA/Member%20Center/FIles/Dental_Radiographic_Examinations_2012.pdf. Published 2012. Accessed April 20, 2019.
8. National Commission of Radiation Protection and Measurements. Report No. 145: Radiation protection in dentistry. 2003.
9. 20.1001 Definitions. United States Nuclear Regulatory Commission website. https://www.nrc.gov/reading-rm/doc-collections/cfr/part020/part020-1003.html. Updated August 24, 2018. Accessed April 20, 2019.
10. McDaniel TF, Prashar V. Comparison of state dental radiography safety regulations. Gen Dent. 2015;63(4):67-72.
11. US Food & Drug Administration. Radiation safety considerations for x-ray equipment designed for hand-held use. https://www.fda.gov/regulatory-information/search-fda-guidance-documents/radiation-safety-considerations-x-ray-equipment-designed-hand-held-use. Published December 24, 2008. Accessed April 20, 2019.
12. Mahdian M, Pakchoian AJ, Dagdeviren D, et al. Using hand-held dental x-ray devices: ensuring safety for patients and operators. J Am Dent Assoc. 2014;145(11):1130-1132. doi:10.14219/jada.2014.85.
Windy Rothmund, MSDH, RDH, is a professor in the dental hygiene program at Eastern Washington University in Spokane, Washington. In addition to more than 20 years of experience in private practice, her teaching experiences include head and neck anatomy, radiology, first-year clinic lead, and graduate courses. She is an advocate for oral health and serves as chair-elect for the American Dental Education Association Section on Addiction.