# Comparative Dosimetry of Handheld Versus Wall-Mounted Intraoral X-ray Systems: A Phantom-Based Study

## TL;DR

This study compares radiation exposure from handheld and wall-mounted dental X-ray units, finding that handheld units expose operators and patients to higher doses despite similar image quality.

## Contribution

The study provides a quantitative comparison of radiation doses and image quality between two types of dental X-ray systems using a standardized phantom.

## Key findings

- Handheld units delivered significantly higher operator doses at fingers, chest, and thyroid compared to wall-mounted units.
- The effective dose to the patient-equivalent phantom was higher for the handheld unit than the wall-mounted unit.
- Ambient scatter at 1 meter was three times higher for the handheld device.

## Abstract

Introduction: The rapid adoption of handheld dental X-ray units has revolutionized imaging in mobility-restricted patients; however, concerns may still persist regarding their radiation safety profile compared with traditional wall-mounted systems. The aim of the present study was to quantitatively compare operator- and patient-equivalent radiation doses, ambient scatter, and diagnostic image quality between a handheld (MaxRay Cocoon, Dexcowin Co. Ltd., Korea) and a wall-mounted (Optima DC, Alerio Technologies Pvt. Ltd., India) intraoral X-ray unit during standardized mandibular molar radiography.

Materials and methods: This prospective experimental study was conducted using a human cadaver mandible as a standardized phantom. A total of 384 exposures (198 per device) were performed with identical exposure time (0.18 seconds), rectangular collimation, and a size-2 complementary metal-oxide-semiconductor (CMOS) digital sensor using the paralleling technique. Operator doses were recorded using real-time electronic personal dosimeters (RaySafe i3, RaySafe, Sweden) at the chest and thyroid levels and thermoluminescent dosimeters (TLD-100) placed under the lead apron at the chest, forehead, and fingers of the dominant hand. The patient-equivalent effective dose was calculated from dose-area product (DAP) measurements using conversion coefficients recommended by the International Commission on Radiological Protection. Image quality was evaluated objectively through signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) measurements and subjectively by three blinded experienced oral radiologists using a five-point Likert scale. Data were analyzed using independent sample t-tests.

Results: The handheld unit produced significantly higher operator doses: finger dose 0.45 ± 0.12 µSv vs. 0.08 ± 0.03 µSv (p < 0.001), chest (outside apron) 0.18 ± 0.05 µSv vs. 0.05 ± 0.02 µSv (p = 0.001), and thyroid 0.11 ± 0.03 µSv vs. 0.04 ± 0.01 µSv (p = 0.003). The effective dose to the mandible phantom was 2.65 ± 0.25 µSv (handheld) vs. 1.82 ± 0.18 µSv (wall-mounted) (p < 0.001). The ambient scatter at 1 m was three times higher for the handheld device (p < 0.001). No significant differences were found in SNR (p = 0.125), CNR (p = 0.08), or subjective diagnostic quality scores (p = 0.65).

Conclusions: Despite comparable diagnostic image quality, the handheld dental X-ray unit delivered substantially higher radiation doses to both the operator and the patient-equivalent phantom than the wall-mounted system. Wall-mounted units should remain the standard where patient mobility permits, reserving handheld systems for clinically justified scenarios.