Pediatric Radiography: Techniques, Positioning, and Dose Reduction

Why Pediatric Radiography Is Different

Pediatric radiography is one of the most challenging and rewarding areas of radiologic technology. Children are not simply small adults — they differ in anatomy, physiology, emotional development, and radiation sensitivity. Every rad tech who works with pediatric patients must adapt their positioning techniques, exposure factors, immobilization methods, and communication style to the child's age, size, and developmental stage.

The stakes are higher too. Children are significantly more radiosensitive than adults because of their rapidly dividing cells and longer lifetime risk of radiation-induced cancer. The Image Gently campaign estimates that a child's lifetime cancer risk from radiation is two to three times higher than an adult's for the same organ dose. This makes the ALARA (As Low As Reasonably Achievable) principle absolutely paramount in pediatric imaging.

Beyond radiation concerns, you'll face unique positioning challenges: a squirming toddler cannot hold still for a chest X-ray the way an adult can; a frightened preschooler may refuse to enter the X-ray room; and a premature infant in the NICU requires a completely different approach than a school-age child. This guide covers everything you need to know to produce diagnostic-quality pediatric images while minimizing dose, reducing repeats, and providing compassionate care.

Understanding Pediatric Radiation Sensitivity

The biologic effects of radiation are more pronounced in children for several well-established reasons. First, children have a higher proportion of rapidly dividing cells than adults, and rapidly dividing cells are more radiosensitive (this is the cellular basis of the Law of Bergonié and Tribondeau, which you will encounter on the ARRT exam). Second, children have a longer expected lifespan during which radiation-induced cancers can develop. Third, their smaller body size means that organs are closer together, so scatter radiation affects neighboring tissues more significantly.

The effective dose for a pediatric chest X-ray ranges from approximately 0.01 to 0.05 mSv depending on the child's age and technique — compared to 0.1 mSv for an adult PA and lateral chest. But the attributable lifetime risk of cancer from that dose is approximately 2-3× higher for a one-year-old than for a 50-year-old adult. This is why the Image Gently campaign emphasizes:

• One size does not fit all — use size-based technique charts, not weight-based or age-based approximations
• Child-size the technique — reduce kVp and mAs proportionally to body thickness
• Don't use adult grids for children — grid use in pediatric imaging should be limited to children over approximately 20 kg (about age 6-7) for most exams
• Limit repeats — immobilization and clear communication are dose-saving strategies

Immobilization Techniques for Every Age

Immobilization is the single most important skill in pediatric radiography. Motion artifact is the leading cause of repeat exposures in children, and every repeat doubles the radiation dose for that body part. Proper immobilization is therefore both a quality and a safety intervention. The approach depends entirely on the child's age and developmental stage.

Infants (0-12 months)

Infants cannot follow instructions and have minimal voluntary movement control, but they also have predictable positioning needs. The most important tools for infant immobilization include:

• Pigg-O-Stat — the most common commercial immobilization device for infant and toddler chest X-rays. It consists of a clear plastic chair with adjustable vertical supports and arm restraints. The child sits upright, arms raised above the head, and the technologist can obtain a true AP or PA chest without rotation. Proper use requires two technologists for initial positioning.
• Sandbags and tape — for extremity imaging, pediatric sandbags and non-allergenic medical tape provide gentle but effective immobilization. Never use tape on fragile neonatal skin without a protective barrier (gauze or cotton padding underneath).
• Swaddling (papoose technique) — for infants under 6 months, wrapping the child snugly in a sheet or blanket (with the arms at the sides) provides comfort and limits motion. A commercial pediatric immobilizer (Octostop or similar) uses Velcro straps with foam padding for whole-body immobilization.
• Parental assistance — with the parent wearing a lead apron and thyroid shield, they can hold the infant in position while the exposure is made. This requires clear communication: "Hold your child exactly like this, do not move, and I will count to three before the X-ray."

Toddlers and Preschoolers (1-5 years)

This age group presents the greatest challenge. Toddlers are mobile, curious, and often fearful of the X-ray room. Key strategies include:

• Distraction techniques — use the "TV monitor trick" by having a video play on a phone or tablet held by the parent while you position. Slightly older children may respond to sticker rewards ("if you stay very still like a statue, you get a dinosaur sticker").
• Pigg-O-Stat or Octostop — for children who cannot hold still for chest or abdomen X-rays, these devices are essential. The clear plastic construction allows visualization of the child throughout the exposure.
• Tunnel positioning for extremities — for hand, wrist, forearm, or foot X-rays, position the extremity on the IR and have the parent or technologist gently hold the proximal portion while the distal portion rests on the table. Explain "we're going to take a picture of your hand — keep it as flat as a pancake."
• Manual stabilization — for AP pelvis or hip imaging, the frog-leg position (knees flexed, soles of feet together) naturally limits motion. A parent in a lead apron can gently hold the child's knees in position.

School-Age Children (6-12 years)

Most children in this age range can cooperate with instructions, but they may still be anxious or self-conscious. Strategies shift from physical immobilization to psychological preparation:

• Explain the procedure — use age-appropriate language: "I'm going to take a special picture of your chest. It won't hurt at all. You'll hear a buzzing sound like a bee. Hold your breath when I say 'breathe in and blow out'."
• Demonstrate the breathing instruction — practice one or two breath-hold cycles before the exposure. Children respond well to "breathe in like you're blowing up a balloon, then hold it."
• Use the upright bucky — for chest X-rays, the standing position with the chin on the bucky is usually well-tolerated. Adjust the height so the child is comfortable and stable.
• Parental presence — most children do better with a parent in the room. Ensure the parent is properly shielded and positioned away from the primary beam.

Age-Specific Positioning Modifications

Pediatric positioning requires modifications to standard adult projections. Here is a guide to the most common pediatric X-ray examinations with their specific positioning requirements.

Pediatric Chest X-Ray (Chest Series)

The chest X-ray is the most common pediatric radiographic examination. Indications include suspected pneumonia, bronchiolitis, foreign body aspiration, cardiomegaly, and routine evaluation of respiratory distress.

Infants (supine AP): The child lies supine on the IR (or on top of the IR placed in a cassette tunnel underneath the table). Center the CR to the mid-sternum at the level of the nipples (T4-T5). Use 50-60 kVp and 1-2 mAs for a term newborn; adjust upward for larger infants. Collimate tightly to the lung fields — do not routinely include the entire abdomen. Inspiratory phase is critical; expose at the peak of inspiration when the infant is breathing in (observe the rise of the chest).

Toddlers (upright or seated): Use the Pigg-O-Stat for children under 4. The child sits upright; arms are raised above the head (this elevates the clavicles and scapulae above the lung apices). Center CR to T4-T5. Technique: 55-65 kVp, 2-4 mAs depending on body habitus. For the lateral view, the arms are raised and the child is rotated 90 degrees; center to the mid-thorax at T7.

School-age (upright PA): Standard adult PA chest positioning, but with an appropriate SID of 72 inches (180 cm). If the child cannot reach the upright bucky, seat them on a stool. Center CR at T4-T5. Technique: 60-70 kVp, 3-6 mAs. Use AEC with the center chamber selected.

Pediatric Abdomen (KUB)

Indications include suspected obstruction, constipation, foreign body ingestion, necrotizing enterocolitis (NEC) in neonates, and unexplained abdominal pain. The supine AP abdomen (KUB) is the standard projection.

Infants: Center CR at the level of the iliac crests. For NEC evaluation in preterm infants, obtain both supine and left lateral decubitus views (to assess for pneumatosis and free air). Use 55-65 kVp and 1.5-3 mAs. Collimate from the diaphragm to the symphysis pubis.

Older children: Center at the iliac crests, using a 14×17 inch IR for most children (adjust 10×12 if smaller coverage suffices). Use 60-75 kVp and 3-8 mAs. For the erect abdominal view (free air evaluation), carefully assist the child to a standing position. The left lateral decubitus view (child lying on left side, horizontal beam) is often better tolerated by sick children than the erect position.

Pediatric Extremity X-Rays

Trauma-related extremity X-rays are extremely common in pediatric imaging. Growth plates (physes) are the most important anatomical consideration — they appear as radiolucent lines and must not be mistaken for fractures.

Key considerations for pediatric extremities:

• Always obtain at least two projections (AP and lateral) 90 degrees apart
• Include the joint above and below the suspected injury
• Use the smallest IR that covers the area of interest
• When a fracture is suspected, the child may refuse to move the injured extremity — never force positioning
• For suspected non-accidental trauma (NAT/child abuse), a skeletal survey requires a specific protocol with dedicated views of every bone

Table 1: Pediatric technique chart — approximate exposure factors. Always adjust for body habitus and equipment-specific factors. mAs values assume no grid; multiply by grid conversion factor when using a grid.

Dose Reduction Strategies That Work

Dose reduction in pediatric imaging requires an active, deliberate approach. Simply using "lowest settings" is not enough — every exposure factor must be optimized for the individual child.

Size-Based Technique Selection

The most effective dose reduction strategy is matching the technique to the child's actual body thickness, not their age or weight. Two children of the same age can have dramatically different body habitus. Use calipers to measure the body part thickness whenever possible. The general rule: for every 4-5 cm increase in thickness, double mAs; conversely, for smaller pediatric patients, reduce mAs proportionally below the adult baseline.

Grid Management

Grids significantly increase patient dose because the mAs must be increased by the Bucky factor (typically 3-5×) to compensate for primary radiation absorption. For children under approximately 20 kg (about age 6-7), do not use a grid for most examinations. The scatter-to-primary ratio in small body parts is low enough that grid use provides minimal contrast improvement while substantially increasing dose. For children over 20 kg, consider using a grid only for body parts thicker than 12 cm.

Collimation

Precise collimation is arguably the most powerful dose-saving tool available. Tight collimation reduces the volume of irradiated tissue directly. It also reduces scatter radiation, improving image contrast. For every pediatric examination, collimate to the area of clinical interest before making the exposure. Do not routinely image beyond the anatomical boundaries — for example, a pediatric chest X-ray does not need to include the entire abdomen and pelvis.

Exposure Time and Motion

Use the shortest possible exposure time (high mA, short time) to freeze voluntary and involuntary motion. In pediatric imaging, exposure times should ideally be under 10-20 milliseconds. This means using the highest mA station available and the shortest time that delivers the required mAs. For example, instead of 100 mA at 0.05 seconds (5 mAs), use 200 mA at 0.025 seconds (still 5 mAs) — the shorter time reduces motion artifact, which prevents repeat exposures.

Shielding Considerations

The topic of gonadal shielding in pediatric imaging has changed significantly. The AAPM (American Association of Physicists in Medicine) and ACR (American College of Radiology) no longer recommend routine gonadal shielding for pelvic X-rays in any patient, including children. The reasons are:

• Modern collimation and digital detectors have reduced scatter such that the additional dose reduction from shielding is negligible (<1% of effective dose)
• Shielding can obscure anatomy, requiring repeat exposures
• Shielding can inadvertently increase dose if the AEC chambers are covered by the shield
• Shielding may provide a false sense of security that replaces more effective interventions (collimation, optimal technique)

However, some states and institutions still require gonadal shielding per their regulations. Know your facility's policy. The most important intervention remains proper collimation and optimal technique selection.

Communication and Age-Appropriate Care

Your communication approach directly affects image quality. A child who is calm and trusts you will be more cooperative, reducing the likelihood of motion on the image and the need for repeat exposures. Here is an age-based communication framework:

Infants (0-12 months)

Communicate primarily with the parent or guardian. Explain what you will do step by step before doing it. Infants are sensitive to their parents' emotional state — if the parent is anxious, the baby will sense it. Speak calmly to the parent first, then interact with the baby in a gentle, soothing voice. Never leave an infant unattended on the X-ray table — even a newborn can roll off a narrow table.

Toddlers (1-3 years)

Toddlers are at the peak of stranger anxiety and are just beginning to assert their independence. Use simple, concrete language. Avoid asking yes/no questions that invite refusal ("Can you lie down for me?"). Instead, use declarative statements with choices where possible: "It's time to take a picture of your arm. Do you want to sit on mommy's lap or on the table?" Offer a reward: "When you're done, you get a sticker!"

Preschoolers (3-5 years)

Preschoolers have active imaginations and may fear the X-ray equipment. Use medical play when appropriate — let them see the X-ray tube from a distance and explain it in non-threatening terms: "This big camera is going to take a secret picture of your bones. It will make a funny buzzing sound, but it won't hurt at all." Use a countdown technique: "I'll count to three, and on three the camera goes 'beeeeep.' Ready?"

School-Age Children (6-12 years)

These children can understand detailed explanations but may be embarrassed about exposing body parts or about being seen in a medical setting. Provide honest, straightforward information. Explain what you need them to do and why: "I need you to hold your breath for this picture because if you breathe, the lungs will look blurry and the doctor won't be able to see if you have pneumonia." Respect their modesty — use gowns and drapes appropriately.

Adolescents (13-17 years)

Adolescents should be treated more like adults. Explain the procedure directly to the patient, not just to the parent. Ask if they have questions. Ensure modesty and privacy — adolescents are particularly sensitive about physical exposure. If a parent is present, ask the adolescent if they prefer the parent to stay or step out for certain examinations (consistent with your facility's chaperone policy).

Common Pediatric Exams: Step-by-Step Positioning

Here are step-by-step positioning instructions for the three most common pediatric radiographic examinations you will perform as a rad tech.

Infant Chest X-Ray (Supine AP)

1. Prepare: Select the smallest IR that covers the chest (typically 8×10 or 10×12 inch). Remove clothing and diaper from the chest area. Place the IR in the cassette tunnel under the table (or use a DR detector).
2. Position: Place the infant supine on the table. The parent or nurse can be nearby for reassurance. Center the child's chest over the IR so that the CR is at T4-T5 (nipple line).
3. Immobilize: Gently hold the infant's arms above the head (this moves the arms out of the lung fields). Sandbags on either side of the torso provide additional stability.
4. Collimate: Tightly to the lung fields — from just above the clavicles to the lung bases (approximately T12-L1).
5. Respiration: Expose at the peak of inspiration. Observe the infant's chest rising and trigger the exposure during the inspiratory pause. For uncooperative crying infants, expose during a cry (which is essentially a held expiration after a deep inspiration — surprisingly diagnostic).
6. Technique: 50-60 kVp, 1-3 mAs. No grid. SID: 40 inches (100 cm).

Pediatric Wrist X-Ray (PA and Lateral)

1. PA projection: Seat the child beside the table with the affected arm extended onto the IR. The hand is pronated, fingers slightly spread, wrist centered to the IR. Center CR to the mid-carpal area. Collimate to just proximal to the radial styloid process and just distal to the metacarpal bases.
2. Lateral projection: From the PA position, rotate the wrist 90 degrees into a true lateral (ulnar side down on the IR). The fingers are extended and the thumb is relaxed. Center CR to the wrist joint.
3. Immobilization: For young children, have the parent hold the upper arm (proximal to the elbow) while the child's hand rests flat on the IR. Tape may be used gently over the fingers for the lateral view.
4. Technique: 50-55 kVp, 1.5-3 mAs. No grid. SID: 40 inches (100 cm).

Pediatric Pelvis (AP with Frog-Leg View)

1. AP pelvis: The child lies supine with legs extended. The IR is positioned so that it covers from the iliac crests superiorly to the greater trochanters inferiorly. Center CR to the midpoint between the ASIS and the symphysis pubis. For infants being screened for developmental dysplasia of the hip (DDH), internal rotation is not required.
2. Frog-leg (modified bilateral): From the supine position, flex both knees and bring the soles of the feet together. Allow the knees to fall outward (externally rotate) as far as comfortably possible. This is the most important view for evaluating DDH.
3. Immobilization: For infants, a parent in a lead apron can hold the child's hands at the chest (above the X-ray field). For toddlers, the Pigg-O-Stat in a seated position is sometimes used.
4. Technique: 55-70 kVp, 2-8 mAs depending on size. No grid for children under 20 kg.

Special Considerations: NICU and PICU Imaging

Portable radiography in the Neonatal Intensive Care Unit (NICU) and Pediatric Intensive Care Unit (PICU) demands special attention. These patients are often on ventilators, have multiple lines and tubes, and are medically fragile. Before every NICU/PICU portable examination:

• Review the clinical indication — what is the clinical question? Is it line/tube placement? Pneumothorax? NEC?
• Coordinate with the nursing team — ask the nurse if the patient is stable enough for repositioning
• Check lines and tubes — know what the existing lines look like (ET tube, NG tube, UAC, UVC, chest tubes) so you can properly assess placement on the image
• Use the portable grid judiciously — for infants, a grid is almost never needed
• Maintain sterile technique — if the child is in an isolette, use the portholes if possible
• Expose on expiration for pneumothorax evaluation — a chest X-ray taken at end-expiration accentuates the visibility of a pneumothorax, but this must be balanced against the difficulty of timing with an infant's irregular breathing

Non-Accidental Trauma (Child Abuse) Imaging

As a radiologic technologist, you may be the first healthcare professional to identify signs of child abuse on radiographs. The skeletal survey for suspected non-accidental trauma (NAT) is a critical examination, and it must be performed with meticulous technique. The ACR-SPR guideline for skeletal surveys in suspected NAT includes:

Required views (infants and children under 2 years):

• Appendicular skeleton: AP humeri (bilateral), AP forearms (bilateral), AP femurs (bilateral), AP lower legs (bilateral), PA hands (bilateral), AP feet (bilateral)
• Axial skeleton: AP chest (including both clavicles), lateral chest (including thoracic and lumbar spine), AP abdomen (including pelvis and lumbosacral spine), lateral cervical spine (if indicated), AP and lateral skull

Key technique considerations:

• Each anatomical region is imaged separately — do not use a single "babygram" (whole-body IR) as it compromises image quality for all regions
• All images must be of diagnostic quality — a poor-quality NAT survey may miss fractures
• Use detail (mammography) cassettes or high-resolution DR detector settings for extremity views
• Label each image with the anatomical part, not just "skeletal survey"
• If initial images are suspicious, follow-up imaging in 10-14 days (to assess for healing fractures) is often requested

Pediatric vs Adult: Key Differences at a Glance

Putting It All Together: A Pediatric Imaging Checklist

Before every pediatric radiographic examination, mentally run through this checklist:

1. Is this exam indicated? — Review the order. Is there a valid clinical indication? Can it be deferred until the child can cooperate better?
2. What immobilization method will I use? — Select the appropriate device or approach before bringing the child into the room.
3. What is my technique? — Use size-based factors from your facility's pediatric technique chart. Measure thickness if needed.
4. Do I need a grid? — If the child is under 20 kg, skip the grid for almost every exam.
5. How will I communicate? — Adapt your language to the child's developmental stage. Involve the parent.
6. Where is my collimation? — Set it tight before the exposure. Avoid unnecessary irradiation of adjacent anatomy.
7. What is my SID and CR centering? — Confirm before making the exposure.
8. Is the child ready? — Check the position, respiration phase, and immobilization. Take the exposure.
9. Is the image diagnostic? — If not, reassess before repeating. Change something (technique, position, immobilization).
10. Document. — Note all exposures, the method of immobilization, and the child's cooperation level.