329 lines
8.9 KiB
Markdown
329 lines
8.9 KiB
Markdown
# Standard Operating Procedure: CT Imaging Protocol
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| Document ID | SOP-RAD-001 |
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|-------------|-------------|
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| Title | Computed Tomography (CT) Imaging Protocol |
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| Revision | 1.0 |
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| Effective Date | [DATE] |
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| Author | [AUTHOR] |
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| Approved By | [APPROVER] |
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| Department | Radiology/Diagnostic Imaging |
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---
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## 1. Purpose
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To establish standardized procedures for performing computed tomography (CT) examinations to ensure patient safety, optimal image quality, and regulatory compliance with ACR, state, and federal requirements.
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## 2. Scope
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This procedure applies to all CT examinations including:
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- Non-contrast CT studies
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- Contrast-enhanced CT studies
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- CT angiography (CTA)
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- CT-guided procedures
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- Emergency/trauma CT
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## 3. Responsibilities
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### 3.1 CT Technologist
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- Screen patients for contraindications
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- Position patient properly
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- Select and execute protocols
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- Assess image quality
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- Monitor patient during examination
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### 3.2 Radiologist
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- Approve protocols
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- Supervise contrast administration
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- Interpret studies and generate reports
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- Manage contrast reactions
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### 3.3 Radiology Nurse (if applicable)
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- Assess IV access
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- Administer contrast
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- Monitor for reactions
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- Provide patient care
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### 3.4 Medical Physicist
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- Establish dose optimization protocols
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- Perform quality control
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- Monitor radiation exposure
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## 4. Definitions
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| Term | Definition |
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|------|------------|
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| CTDI | CT Dose Index - measure of radiation output |
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| DLP | Dose Length Product - total dose metric |
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| HU | Hounsfield Units - density measurement |
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| kVp | Kilovoltage peak |
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| mAs | Milliampere-seconds |
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| MPR | Multiplanar reconstruction |
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## 5. Equipment and Materials
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- CT scanner (accredited)
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- Power injector
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- Contrast media (iodinated)
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- IV supplies
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- Emergency equipment and medications
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- Shielding devices
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- Patient monitoring equipment
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## 6. Procedure
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### 6.1 Pre-Examination
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#### 6.1.1 Order Verification
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- [ ] Valid physician order present
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- [ ] Appropriate indication documented
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- [ ] Protocol selection appropriate for indication
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- [ ] Prior imaging reviewed (if available)
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#### 6.1.2 Patient Identification
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- Verify using two identifiers
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- Confirm exam matches order
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- Review clinical history
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#### 6.1.3 Safety Screening
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**For all patients:**
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- [ ] Pregnancy status (women of childbearing age)
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- [ ] Previous CT studies (cumulative dose awareness)
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- [ ] Ability to cooperate with positioning
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- [ ] Metal implants/devices in scan field
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**For contrast studies - additional screening:**
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| Risk Factor | Check |
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|-------------|-------|
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| Previous contrast reaction | ☐ Yes ☐ No |
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| Allergies (iodine, shellfish) | ☐ Yes ☐ No |
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| Kidney disease/elevated creatinine | ☐ Yes ☐ No |
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| Diabetes (metformin use) | ☐ Yes ☐ No |
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| Thyroid disease | ☐ Yes ☐ No |
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| Multiple myeloma | ☐ Yes ☐ No |
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| Age >70 years | ☐ Yes ☐ No |
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| Dehydration | ☐ Yes ☐ No |
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**Renal Function Assessment:**
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| eGFR Level | Risk | Action |
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|------------|------|--------|
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| ≥60 | Low risk | Proceed |
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| 45-59 | Moderate risk | Hydration, consider alternatives |
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| 30-44 | High risk | Alternative imaging preferred, radiologist approval |
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| <30 | Very high risk | Avoid unless emergent, nephrology consult |
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#### 6.1.4 Consent
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- Explain procedure and risks
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- Obtain informed consent for contrast (if applicable)
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- Document consent
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### 6.2 Patient Preparation
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#### 6.2.1 Preparation by Exam Type
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| Exam Type | Preparation Required |
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|-----------|---------------------|
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| Head CT | Remove metallic objects from head/neck |
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| Chest CT | Breathing instructions, arms above head |
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| Abdomen/Pelvis CT | Oral contrast (if ordered), full bladder (pelvic) |
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| CT Angiography | IV access, contrast protocol |
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| CT Colonography | Bowel preparation |
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#### 6.2.2 IV Access for Contrast
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- Assess vein suitability
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- 20-gauge or larger preferred for power injection
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- Verify patency with saline flush
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- Secure catheter properly
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### 6.3 Patient Positioning
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#### 6.3.1 Standard Positions
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| Body Part | Position | Gantry Entry |
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|-----------|----------|--------------|
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| Head | Supine, neutral | Head first |
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| Neck | Supine, neck extended | Head first |
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| Chest | Supine, arms up | Head or feet first |
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| Abdomen | Supine, arms up | Head first |
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| Pelvis | Supine, arms up | Feet first |
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| Extremity | Per protocol | Varies |
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#### 6.3.2 Positioning Considerations
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- Center patient in gantry
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- Use positioning aids as needed
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- Apply shielding where appropriate
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- Ensure patient comfort
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- Remove all artifacts from scan field
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### 6.4 Protocol Selection and Parameters
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#### 6.4.1 Dose Optimization Principles
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- ALARA (As Low As Reasonably Achievable)
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- Use automatic exposure control (AEC)
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- Size-appropriate protocols
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- Limit scan range to clinical question
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#### 6.4.2 Standard Protocol Parameters
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| Protocol | kVp | mAs | Slice Thickness | Pitch |
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|----------|-----|-----|-----------------|-------|
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| Head routine | 120 | Auto | 5mm | N/A (axial) |
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| Chest routine | 120 | Auto | 5mm/1.25mm | 1.0-1.5 |
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| Abdomen routine | 120 | Auto | 5mm/2.5mm | 1.0-1.5 |
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| CT Angiography | 100-120 | Auto | 0.625-1.25mm | 0.8-1.0 |
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| Low-dose chest | 100-120 | Reduced | 1.25mm | 1.0-1.5 |
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#### 6.4.3 Pediatric Considerations
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- Reduce kVp and mAs based on weight/age
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- Use pediatric-specific protocols
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- Apply "Image Gently" principles
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- Minimize number of phases
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### 6.5 Contrast Administration
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#### 6.5.1 Contrast Selection
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| Indication | Contrast Type | Concentration |
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|------------|---------------|---------------|
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| Routine enhanced | Low-osmolar | 300-350 mgI/mL |
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| CT Angiography | Low-osmolar | 350-370 mgI/mL |
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| High-risk patients | Iso-osmolar | 270-320 mgI/mL |
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#### 6.5.2 Contrast Volume and Rate
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| Exam Type | Volume | Rate |
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|-----------|--------|------|
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| Head with contrast | 100 mL | 1-2 mL/sec |
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| Chest with contrast | 100-125 mL | 2-3 mL/sec |
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| Abdomen with contrast | 100-150 mL | 2-3 mL/sec |
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| CT Angiography | 75-125 mL | 4-5 mL/sec |
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#### 6.5.3 Timing Methods
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- Fixed delay (empiric)
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- Bolus tracking (threshold trigger)
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- Test bolus (timing determination)
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### 6.6 Image Acquisition
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1. **Scout/Topogram**
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- Acquire scout images
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- Verify positioning and coverage
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- Set scan range
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2. **Pre-Contrast (if applicable)**
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- Acquire non-contrast images
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- Assess for baseline findings
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3. **Contrast Injection (if applicable)**
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- Verify IV patency
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- Program injector parameters
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- Monitor injection
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4. **Post-Contrast Acquisition**
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- Acquire at appropriate phase(s)
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- Arterial: 25-35 seconds
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- Portal venous: 60-70 seconds
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- Delayed: 3-5 minutes (as needed)
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5. **Image Review**
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- Review images for quality
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- Assess for artifacts
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- Repeat if technically inadequate
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### 6.7 Post-Examination
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#### 6.7.1 Patient Care After Contrast
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- Monitor for 15-30 minutes
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- Assess IV site
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- Provide hydration instructions
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- Advise on potential delayed reactions
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- Metformin patients: follow institutional protocol
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#### 6.7.2 Documentation
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- Complete FRM-RAD-001 CT Procedure Log
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- Document dose metrics (CTDIvol, DLP)
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- Record contrast details
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- Note any adverse events
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- Submit images to PACS
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### 6.8 Image Post-Processing
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| Reconstruction | Application |
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|----------------|-------------|
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| Soft tissue | Routine interpretation |
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| Bone | Skeletal evaluation |
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| Lung | Pulmonary parenchyma |
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| 3D/MPR | Vascular, complex anatomy |
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| MIP | Angiography |
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## 7. Contrast Reaction Management
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### 7.1 Reaction Classification
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| Severity | Symptoms | Action |
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|----------|----------|--------|
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| Mild | Nausea, urticaria (limited), warmth | Observe, treat symptoms |
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| Moderate | Extensive urticaria, bronchospasm, hypotension | Medical treatment, monitor |
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| Severe | Anaphylaxis, cardiac arrest, seizure | Emergency response, call code |
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### 7.2 Emergency Equipment
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Available in CT suite:
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- Oxygen and suction
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- Emergency medications (epinephrine, diphenhydramine, etc.)
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- IV fluids
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- Defibrillator/AED
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- Crash cart
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## 8. Radiation Safety
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### 8.1 Dose Monitoring
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- Record CTDIvol and DLP for each exam
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- Compare to diagnostic reference levels
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- Investigate outliers
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### 8.2 Diagnostic Reference Levels
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| Exam | CTDIvol (mGy) | DLP (mGy·cm) |
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|------|---------------|--------------|
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| Head | 60 | 1000 |
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| Chest | 15 | 400 |
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| Abdomen | 20 | 700 |
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| Abdomen/Pelvis | 20 | 900 |
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## 9. Quality Control
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| Activity | Frequency |
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| Daily warm-up and calibration | Daily |
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| Water phantom QC | Daily/Weekly |
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| CT number accuracy | Weekly |
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| Spatial resolution | Monthly |
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| Physicist review | Annually |
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## 10. Documentation
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- FRM-RAD-001 CT Procedure Log
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- FRM-RAD-002 Contrast Administration Record
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- FRM-RAD-003 Adverse Reaction Report
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- Dose reports
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- QC logs
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## 11. References
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- ACR Practice Parameter for CT
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- ACR Manual on Contrast Media
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- Image Gently Campaign
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- AAPM CT Protocols
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- State radiation regulations
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---
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## Revision History
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| Rev | Date | Description | Author |
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|-----|------|-------------|--------|
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| 1.0 | [DATE] | Initial release | [AUTHOR] |
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