Radiation protection protocol

This protocol sets out the general guidelines governing the use of ionizing radiation equipment at the imaging center, intended to protect the health of patients, staff and the general public, in accordance with the fundamental radiation protection principles recognized by the International Commission on Radiological Protection (ICRP) and the International Atomic Energy Agency (IAEA).

1. Center data and responsible parties

2. Fundamental principles

All use of ionizing radiation at the center is governed by three principles:

• Justification: no study is performed if its net benefit (diagnostic or therapeutic) does not outweigh the potential harm. Each request must be supported by a clinical indication documented by the requesting professional.
• Optimization (ALARA): "As Low As Reasonably Achievable". The dose received by the patient must be the minimum necessary to obtain the required diagnostic information, taking economic and social factors into account.
• Dose limitation: applied to occupationally exposed staff and to the public. It does not apply directly to the individual patient (where justification governs), but it does apply to the center's staff.

3. Justification of studies

Each study must be justified by a written clinical indication. The center maintains the following criteria:

• The referral or request form must state the indication (see referral form template at /ayuda/recursos).
• In case of an ambiguous or unjustified indication (for example "routine check without symptoms"), the center contacts the requester before proceeding.
• The lowest-dose modality compatible with the clinical question is preferred: panoramic/periapical before CBCT when diagnostically equivalent; small FOV before large FOV.
• In pediatrics: CBCT is only performed when the additional information over panoramic/periapical justifies the increased dose.
• In pregnancy: studies are deferred to postpartum whenever clinically reasonable. When performed, specific consent and lead abdominal shielding are applied.

4. Optimization (ALARA) in CBCT

To minimize patient dose while preserving diagnostic quality:

• Smallest FOV (Field of View) needed to include the region of interest. FOV ≤ 6 × 6 cm is preferred when sufficient.
• Voxel size appropriate to the indication: large voxel (≥ 0.3 mm) for broad bone studies; fine voxel (0.1–0.2 mm) only when spatial resolution is critical (endodontics, root fractures).
• Equipment parameters (kVp, mA, time) in the lowest compatible dose mode. In pediatrics, pediatric mode always enabled.
• Verify before exposure: positioning, bite, patient stability. A repeat due to a positioning error doubles the dose.
• Audit study repeats monthly. Target rate: <5% of the total.

5. Patient protection

• Lead apron with thyroid collar available and offered to all patients. In dental CBCT the primary beam is directed at the craniofacial complex; the apron protects against scatter radiation to the trunk and especially the thyroid.
• In pregnant patients: lead abdominal and gonadal shielding is mandatory, in addition to documentation of specific consent.
• Communication with the patient about the procedure, its duration, and the importance of staying still.
• Only the patient remains in the room during exposure. If assistance is required (pediatric patients, people with disabilities), the companion uses lead shielding and stands outside the primary beam.

6. Protection of occupationally exposed staff

• All staff with potential exposure use a personal dosimeter (TLD or OSL). Monthly or quarterly readings according to regulation.
• Monthly individual dose record with a minimum archive of 30 years, or the period set by local regulation.
• Occupational dose limit per ICRP/local regulation: typically 20 mSv/year averaged over 5 years, maximum 50 mSv in any single year. Pregnant workers: reinforced limit to the fetus (≤1 mSv during the remainder of the pregnancy from the declaration).
• Staff operate the equipment from behind architectural shielding (lead screen with viewing window) or from outside the room.
• Annual medical surveillance of exposed staff.
• Initial training course in radiation protection upon hiring and periodic refresher courses according to regulation.

7. Signage and shielding

• "Ionizing radiation" (trefoil) sign at the entrance to the room where the equipment is located, clearly visible.
• Active light signage during exposure (red light or equivalent).
• Calculation and verification of architectural shielding (walls, door, windows) in line with equipment workload. Calculation report on file.
• Restricted access to the room during exposure (lock, interlock, or verifiable protocol).

8. Personal protective equipment (PPE)

• Lead aprons (≥ 0.25 mm Pb equivalent) in sufficient quantity
• Lead thyroid collars
• Lead gonadal shielding for specific cases
• Monthly visual integrity check (no cracks or tears)
• Annual radiographic check of aprons to detect internal damage
• Record of each PPE item with serial number, purchase date, and inspections

9. Equipment quality control

• Initial calibration upon installing the equipment, documented by the supplier or authorized technical service.
• Periodic checks (weekly, monthly, annual) according to the manufacturer's program and local regulation: constancy test, beam quality, kVp accuracy, exposure time, image geometry, detector uniformity.
• Annual preventive maintenance by an authorized technical service.
• Equipment logbook with incidents, maintenance, changes and recalibrations. Permanent archive.

10. Staff training

• Mandatory initial radiation protection course upon joining the center, with knowledge test.
• Periodic refresher (at least every 2 years, or as required by local regulation).
• Specific operator training on the CBCT equipment by the supplier or qualified staff.
• Internal dissemination of regulatory updates and international recommendations (ICRP, IAEA).

11. Recording and traceability

The center keeps the following records on file:

• Referral form for each study
• Signed informed consent for each study
• Acquisition parameters and estimated dose per study (DAP, CTDI or equivalent)
• Equipment activity log (power-on, exposures performed)
• Personal dosimetry of exposed staff (monthly/quarterly)
• Radiological incident log (overexposure, malfunction, accidents)
• Record of training received by each staff member
• Equipment quality control documentation

12. Incident management

In the event of a radiological incident (unintended overexposure, equipment failure during exposure, exposure of unauthorized staff, etc.):

1. Stop activity on the affected equipment.
2. Assess the clinical situation of the patient or staff involved.
3. Notify the center's RPO (Radiation Protection Officer).
4. Document the incident in the logbook with date, time, description, people involved, estimated dose and actions taken.
5. Notify the local regulatory authority when required by regulation.
6. Review the procedure that led to the incident and apply improvements.

13. Protocol revision and updating

This protocol is reviewed at least annually by the center's RPO, or sooner when: (a) local regulations are updated; (b) equipment is acquired or replaced; (c) an incident occurs that prompts changes; (d) the regulatory authority requests it.

The date and signature of each review are recorded at the end of this document.