What are the general principles for safely ordering and performing radiological investigations and interventions?

General Principles for Safe Radiological Investigations and Interventions

The overarching principle is that radiological examinations should be performed only when the benefit outweighs the risk, using the lowest radiation dose necessary to achieve diagnostic efficacy while maintaining image quality sufficient for accurate diagnosis. 1

Core Safety Framework

Fundamental Decision-Making Principle

If the risk of illness or death from delaying radiology care exceeds the risk from performing the procedure (including radiation exposure and procedural complications), the examination should proceed; conversely, if the procedural risks outweigh the benefits of timely diagnosis, the study should be deferred. 1

The examination should only be conducted when:

• There is a clear medical indication that will yield information with therapeutic consequences 2
• The diagnostic question cannot be adequately answered by non-ionizing radiation modalities (ultrasound, MRI) 1
• The patient has provided informed consent after adequate explanation of risks, benefits, and alternatives 2

The ALARA Principle (As Low As Reasonably Achievable)

All radiation exposure must be kept as low as reasonably achievable while maintaining diagnostic quality—this is the cardinal axiom for all radiation-based procedures. 1

ALARA implementation requires three fundamental strategies:

• Maximize distance from radiation sources 1
• Minimize time of exposure 1
• Use appropriate shielding for both patients and personnel 1

Pre-Procedure Requirements

Clinical Justification and Appropriate Use

• Apply appropriate use criteria to select patients for radiation-based procedures 1
• Verify that the examination is the preferred choice among available modalities 1
• Consider patient age and life expectancy—younger patients with longer natural life expectancies warrant particular consideration for radiation exposure, though appropriate studies should never be withheld due to undue concern 1
• Ensure the study will provide information that impacts clinical management 2

Informed Consent Requirements

Patients must receive comprehensive information about the objectives, necessity, urgency, procedures, alternatives, and accompanying risks before consent is legally valid. 2

The information threshold varies by urgency:

• Emergency/urgent indications require less extensive consent processes 2
• Purely diagnostic procedures without direct therapeutic value require particularly thorough informed consent 2
• All risks that would influence a reasonable patient's decision must be disclosed 2

Pre-Procedure Safety Assessments

For invasive radiological procedures (e.g., lung biopsy), specific requirements include:

Coagulation screening:

• Check prothrombin time (PT), activated partial thromboplastin time (APTT), and platelet count 1
• Relative contraindications: platelet count <100,000/mL or APTT/PT ratio >1.4 1
• Stop oral anticoagulants according to perioperative anticoagulation guidelines 1
• Consult hematology if coagulation abnormalities exist 1

Pulmonary function assessment (for lung procedures):

• Obtain recent spirometry before needle biopsy 1
• Patients with FEV1 <35% predicted require multidisciplinary team assessment before proceeding 1

Imaging review:

• Review all recent chest radiographs, CT scans, and previous radiological investigations 1
• Repeat imaging if significant clinical change has occurred or significant delay before biopsy 1
• Perform CT preferably before bronchoscopy 1

Equipment and Protocol Optimization

Equipment Quality Assurance

Regular evaluation by qualified medical physicists is mandatory for all radiation-producing equipment. 1

Required quality assurance steps:

• Acceptance testing at initial installation to confirm baseline specifications 1
• Longitudinal surveillance testing performed periodically to identify performance deterioration 1
• Recalibration or renovation when performance deteriorates 1

For fluoroscopy equipment, benchmark calibration values are:

• Low-dose fluoroscopy: 20 nGy/pulse 1
• Standard-dose fluoroscopy: 40 nGy/pulse 1
• Cine acquisition: 200 nGy/pulse 1

Protocol Selection

Develop a culture of selecting imaging protocols that provide satisfactory image quality for the clinical task while employing minimum dose. 1

Specific strategies:

• Set x-ray system defaults to low-dose protocols requiring conscious selection of higher-dose options 1
• Use low-dose fluoroscopy and slow pulse rates for general catheter placement 1
• Reserve standard-dose fluoroscopy and faster pulse rates for tasks requiring greater spatial/temporal resolution 1
• Consider reducing fluoroscopy and cine framing rates (e.g., from 15 to 10 pulses/second achieves 38% dose reduction without compromising efficacy) 1

Image Quality Considerations

Diagnostic accuracy depends critically on adequate image quality—inadequate quality may cause incorrect diagnoses or necessitate repeat examinations with additional radiation exposure. 1

The balance is crucial:

• Diagnostic and therapeutic efficacy should never be compromised solely to spare radiation dose 1
• However, excessive dose without corresponding diagnostic benefit must be avoided 1

Personnel and Patient Protection

Personnel Radiation Safety

In nuclear cardiology and fluoroscopy, personnel rely primarily on time and distance principles since lead aprons are less effective against higher-energy photons. 1

Key personnel protection measures:

• Minimize time in close proximity to radiation sources 1
• Maximize distance from radioactive patients and dose syringes 1
• Recognize that radiopharmaceuticals create continuous radiation sources that can contaminate body fluids 1
• Implement universal masking and appropriate PPE based on procedure type 1

Patient-Specific Considerations

Special populations require heightened attention:

Pregnant patients:

• Fetal exposure risk includes congenital malformations (1 in 500 at 1 rem over gestation) and potential mental retardation (highest risk weeks 8-15 gestational age at 4% per 10 rem) 1
• Limit radiation exposure to 0.05 rem/month for pregnant workers 1
• Severely limit exposure between weeks 8-15 gestational age when possible 1

Pediatric patients:

• Children are particularly vulnerable due to longer life expectancy and greater radiation sensitivity 3
• Tailor imaging protocols individually for pediatric patients 3
• CT scanning is responsible for 24% of all radiation exposure and requires particular scrutiny in children 3

Procedural Execution

Staffing and Monitoring

• Ensure adequate staffing to monitor patients for signs of distress during and after procedures 1
• Operators must be able to identify and appropriately manage complications 1
• Resuscitation facilities and emergency equipment (e.g., chest drain equipment for lung biopsies) must be immediately available 1

Post-Procedure Protocols

For invasive procedures (using lung biopsy as example):

• Perform erect chest radiograph 1 hour post-procedure to detect complications 1
• Patients should remain where staff can be alerted if new symptoms develop in the first hour 1
• Review post-procedure imaging by qualified staff 1
• Inform patients about risks of delayed complications 1
• Consider clinical condition and home circumstances before discharge decisions 1

Follow-Up and Quality Assurance

Recommendation Tracking

Approximately 31% of radiology report recommendations are not executed, with outpatient recommendations most commonly neglected. 4

To improve adherence:

• Use structured radiology reports with dedicated recommendations fields 5
• Specify clear time frames for recommended actions 5
• Minimize contingency language that may create ambiguity 5
• Consider direct communication with ordering physicians for critical recommendations 5
• Implement reliable systems to track completion of actionable recommendations 5

Ongoing Quality Improvement

Establish continuous quality assurance programs that monitor and reduce radiation exposure as new developments emerge. 1

Essential components:

• Track radiation doses for individual procedures and identify trends 1
• Provide feedback to clinical staff and operators characterizing individual performance 1
• Identify and follow up on high-exposure procedures 1
• Monitor equipment quality and calibration 1
• Review imaging protocol selection practices 1

Common Pitfalls to Avoid

• Never perform radiation-based studies without clear therapeutic implications 2
• Do not compromise image quality excessively in pursuit of dose reduction—this may necessitate repeat studies 1
• Avoid neglecting follow-up recommendations, particularly for outpatient studies 4
• Do not proceed with invasive procedures without verifying coagulation status and obtaining appropriate consent 1
• Never assume referring physicians will automatically act on recommendations—implement tracking systems 5