ALARA — As Low As Reasonably Achievable — is the foundational radiation safety principle in dental imaging, requiring clinicians to minimize a patient’s exposure to ionizing radiation while still obtaining images of sufficient diagnostic quality. It is both an ethical obligation and, in most jurisdictions, a regulatory standard that governs how and when dental radiographs are prescribed.

The Core Principle

ALARA is grounded in the understanding that no dose of ionizing radiation is entirely without biological risk, even at the low levels used in routine dental imaging. Cumulative lifetime exposure from repeated radiographic examinations — including bitewing radiographs, periapical radiographs, and panoramic images — must be weighed against the clinical information each study provides. The goal is not to eliminate radiation use, but to ensure every exposure is justified by a clear diagnostic benefit.

How ALARA Is Applied in Clinical Practice

Practitioners implement ALARA through a combination of equipment selection, technique refinement, and individualized prescribing decisions. Key strategies include:

• Selective prescribing — ordering radiographs only when clinical findings or patient history provide a specific indication, rather than on a fixed routine schedule.
• Digital radiography — using digital sensors or phosphor plate systems, which require significantly lower radiation doses than conventional film to produce a diagnostically adequate image.
• Rectangular collimation — restricting the X-ray beam to the precise region of interest to reduce scatter radiation and limit tissue exposure.
• Lead shielding — employing lead aprons and thyroid collars, particularly for children, pregnant patients, and individuals with heightened radiosensitivity.
• Optimized exposure settings — selecting the lowest kilovoltage, milliamperage, and exposure time consistent with acceptable image quality.

Special Considerations for Advanced Imaging

ALARA carries particular weight when evaluating cone beam computed tomography (CBCT), which delivers a substantially higher effective dose than conventional two-dimensional dental radiographs. The volumetric data CBCT provides can be invaluable for implant planning, assessment of impacted teeth, or analysis of complex root morphology — but the indication must be strong enough to justify the increased exposure. Clinicians should confirm that the diagnostic question cannot be adequately answered with lower-dose alternatives before proceeding.

Patient age, reproductive status, medical history, and the availability of prior radiographic records should always factor into prescribing decisions, ensuring that every exposure a patient receives carries a benefit that clearly outweighs its risk.