Mobile radiography brings the imaging system to a patient whose condition or care environment makes transport inappropriate. Bedside work adds constraints—limited space, variable patient position, life-support equipment, infection precautions, and no fixed control booth—but the same requirements still apply: the examination must be justified, correctly identified, optimized for the clinical question, and performed without avoidable exposure.
Use two approved patient identifiers, match the order and body part/side, review relevant precautions, ask about pregnancy when required by policy, and identify every line, drain and support device. Do not move a patient, alter ventilation, inject anything into a tube, or disconnect monitoring equipment independently. Coordinate those actions with the responsible nurse, respiratory therapist, or clinician.
Mobile generators may obtain energy from rechargeable batteries, stored-energy capacitors, or mains power. Designs differ substantially: some batteries power only transport while others also power the generator; generator output, charging behavior, detector integration, focal spots, and available exposure controls are model-specific. Therefore, claims about a universal battery capacity, number of exposures, weight, mA output, or automatic exposure control are unreliable. Use the manufacturer's operator manual and the department's quality-control and technique-chart program.
Inspect the unit before use: brakes and drive controls, tube locks, collimator light, exposure switch and cable, detector integrity, battery/charge status, and required accessories. Keep the detector secured during transport. A tube-conditioning or warm-up sequence is manufacturer-specific; never make unprescribed exposures in a patient area or invent a “two or three exposure” warm-up. Follow the displayed/manual procedure and local radiation-safety arrangements.
Portable chest radiography is used for selected cardiopulmonary questions and for assessment after placement of some devices. It should not be described as automatically required every day for every ICU patient; current ACR guidance distinguishes clinically indicated studies from routine daily imaging in stable patients.
Use the greatest safe head-of-bed elevation the patient's condition permits and record the position because supine, semi-erect and erect images distribute pleural air/fluid differently. Place the detector square to the thorax, high enough to include the apices, with the midsagittal plane centered and without rotating the patient. Direct the beam perpendicular to the detector unless an approved projection requires angulation. Collimate to include both apices, both lateral lungs and both costophrenic angles—without arbitrary extra margins.
Use the facility's validated SID and exposure chart. A long SID, commonly near 180 cm (72 inches) when practicable, reduces magnification, but detector/grid focal range, equipment reach and room geometry govern the actual value. Reproduce SID, patient position and projection for serial images when possible. Expose on a full inspiration when the patient can cooperate. For a ventilated patient, the technologist must not manually bag, disconnect, or change the ventilator; a credentialed clinician may provide a brief inspiratory hold if clinically safe and consistent with local protocol.
Evaluate anatomy and the clinical question rather than treating a rib count as an absolute pass/fail rule. Rotation is assessed from symmetric thoracic landmarks; inspiration can be estimated from diaphragmatic level and visible posterior ribs, but body habitus, projection, disease and patient position alter these signs. AP positioning and short SID can magnify the heart, so avoid interpreting apparent cardiomegaly as if the image were an erect PA chest.
An AP axial (lordotic) projection is a specific additional view, not a routine substitute for a chest radiograph. If requested, use the projection and angle in the department's procedure guide; patient lean and cephalad beam angulation are alternative methods and should not be combined casually.
For a horizontal-beam decubitus chest, place the side of a suspected free pleural effusion down so fluid layers, or the side of a suspected pneumothorax up so pleural air rises. Keep the detector vertical, include both lungs, and use a true horizontal beam. If the patient's condition permits, allow time for mobile air or fluid to redistribute according to the local protocol. Select technique from the decubitus chart—there is no universal “add 5–8 kVp” rule.
A supine AP abdomen commonly centers at the level of the iliac crests and must include the pubic symphysis for a KUB. A single detector often cannot include both diaphragms and the symphysis in a large adult; use the number and orientation of images specified by the order and protocol rather than promising impossible coverage. When free intraperitoneal gas is the question, an erect chest is often part of the protocol; an erect abdomen should include both hemidiaphragms. If the patient cannot be erect, a left lateral decubitus abdomen with a horizontal beam can demonstrate free gas against the liver. The required period upright or decubitus is protocol- and condition-dependent.
For a suspected proximal femur fracture, do not internally rotate the injured leg. Leave it in the position found unless a responsible clinician has excluded fracture and authorizes movement. For a horizontal-beam lateral, elevate or flex the unaffected leg only if safe; place the detector beside the affected hip, align it parallel to the femoral neck, and direct the horizontal beam perpendicular to the detector using the department's landmark and collimation protocol. Select grid, SID, focal spot and exposure from the validated chart. Never substitute an improvised air gap for a required grid.
Obtain the ordered orthogonal projections without forcing a painful limb. Include the required joint(s), hardware and fracture extent. Grid use depends on field size, tissue thickness, kVp, detector and protocol—not a universal 10 cm threshold. Use a focal spot and exposure time that balance detail, tube loading and motion. Technique changes through a plaster or fiberglass cast depend on material, thickness, whether it is wet or dry, and the local chart; a blanket 3–5 kVp increase is not valid.
A grid can improve subject contrast by rejecting scatter, but normally requires more receptor exposure and therefore can increase patient dose. Miscentering, off-level alignment, wrong grid orientation, or use outside a focused grid's focal range can cause cutoff. Digital post-processing cannot restore information lost to severe cutoff.
| Decision | Safe, defensible approach | Avoid |
|---|---|---|
| Grid use | Follow the examination-, detector- and patient-size-specific technique chart. | Universal age or thickness cutoffs and guessed grid ratios. |
| Focused grid | Center accurately, keep the beam perpendicular unless the grid permits angulation, and remain within its stated focal range. | Using a grid focused for one SID at a different SID without verifying its range. |
| Intentional air gap | Use only when included in a validated protocol; account for magnification and unsharpness and adjust SID as prescribed. | Improvising a 10–15 cm gap as a “rescue” for a thick chest, abdomen or hip. |
| Exposure factors | Use the chart and exposure index/deviation index as intended by the detector manufacturer; choose the shortest practical time consistent with adequate receptor exposure. | Increasing mAs to fix scatter, or relying on image brightness to judge digital exposure. |
| Repeat decision | Repeat only when the image cannot answer the clinical question, after identifying and correcting the cause. | Repeating solely for cosmetic positioning differences. |
Collimate before exposure to the anatomy needed for the clinical question. Proper collimation reduces irradiated tissue and scatter and usually improves image contrast. Do not “open up” routinely to avoid repeats, and do not crop an overexposed field afterward as a substitute for physical collimation.
Image the entire relevant course of a device and enough anatomy to identify its tip and complications. Do not rotate the patient or angle the beam merely to project a line away from the spine; that can distort anatomy and device relationships. Unexpected or potentially dangerous placement requires prompt escalation through the facility's critical-results process—not an informal assumption that “the nurse knows.”
Endotracheal tube: On an adult chest image obtained with the neck neutral, the tip is commonly targeted about 5 cm above the carina; an acceptable interval is often described as roughly 3–7 cm, but it varies with age, neck position and local clinical guidance. Flexion moves the tip caudally and extension cranially. Include the thoracic inlet and carina. Radiography is one accepted confirmation method, but it is not the only method and should not be called a universal “gold standard.”
Central venous catheter or PICC: The intended tip location depends on catheter type and purpose. For many upper-body central catheters it is the lower SVC/cavoatrial region, but vertebral levels on a rotated AP image are imperfect surrogates. Trace the line for kinking or malposition and include the chest for procedure-related pneumothorax when that is the indication.
Gastric and enteric tubes: A confirmation image must show the tube continuously from the upper esophagus through the diaphragm to its tip. For gastric use, both tip and side-port should project below the gastroesophageal junction; post-pyloric feeding has a different target. Never pull back a tube or inject air for the radiograph. Air-bolus auscultation does not reliably exclude respiratory placement. Feeding or medication must not begin until an authorized clinician has confirmed position by the approved method.
Chest drain: Show the entire intrathoracic course and all radiopaque side-hole markers. A side hole outside the pleural space can impair drainage, but a single image does not by itself prove whether a drain is functioning or predict a specific complication. Desired direction varies with the indication and insertion technique; evaluate position together with residual air/fluid and clinical findings.
Monitoring equipment: Do not disconnect or reposition electrodes, tubes, pumps, clamps, drains or ventilator components independently. With staff permission, loose external wires may be moved outside the anatomy without traction. Life support and patient stability take priority over a cleaner image.
Before leaving, verify identifiers and marker, projection/position, required anatomy, motion, rotation, penetration/receptor exposure, collimation, and visibility of requested devices. Review the exposure indicator for an unexpected over- or underexposure; acceptable display brightness is not proof of appropriate detector exposure.
For motion, use an approved short-exposure technique and clear breathing instruction. For ventilated patients, coordinate any respiratory pause with the clinician controlling the airway. For apex cutoff, place the detector sufficiently cephalad before centering; do not use unnecessary caudal angulation as a routine fix. For grid cutoff, correct centering, leveling, orientation, SID and grid focal range. If the image answers the clinical question, do not repeat it merely to meet an arbitrary “less than 2 cm rotation” or rib-count rule.
Before exposure, collimate tightly, clear nonessential people, announce the exposure, and make sure no person is in the primary beam. Maximize distance from both patient and tube and use a fixed or mobile protective barrier when available. Many mobile-radiography programs use approximately 2 m as a practical operator distance when no barrier is available, but the safe position must follow local rules, equipment instructions and radiation survey/design. Scatter varies with projection, field size, patient size and room geometry; a claimed universal “90–135° safest sector” is not a substitute for a barrier or survey.
Personal protective equipment is task- and policy-dependent. A 0.5 mm Pb apron and thyroid collar are not universally mandated for every operator who can stand behind a barrier or at a surveyed distance. Anyone who must remain close to the patient should use the protective equipment specified by the radiation-safety program. Never hold the patient or detector routinely. If holding is unavoidable, use a non-occupational helper where permitted, keep that person outside the primary beam, provide instructions and shielding, and document according to policy.
Individual monitoring is assigned from the worker's expected exposure and regulatory requirements. Wear each dosimeter exactly where the radiation safety officer or badge report specifies; placement differs for a single badge, double-badge fluoroscopy program and declared pregnancy monitor. In the United States, NRC limits apply to NRC licensees and comparable state rules may differ: 50 mSv annual total effective dose equivalent, 150 mSv to the lens, and 500 mSv shallow dose to skin or an extremity. These are limits, not dose targets. Declaration of pregnancy is voluntary under NRC rules; after a written declaration, the embryo/fetus limit is 5 mSv for the entire pregnancy, with efforts to avoid substantial variation month to month.
Ask visitors and nonessential staff to leave. Protect patients who cannot leave by maximizing distance, directing the beam away from them, collimating, and using an appropriate barrier under the facility plan. “Go to the corner and turn away” is not a complete radiation-protection instruction.
Fluoroscopy requires procedure-specific training and a coordinated radiation-safety plan. When anatomy and sterility permit, place the X-ray tube under the table and the detector above, keep the detector as close to the patient as practicable, keep the tube as far from the skin as practicable, collimate, use the lowest pulse rate and dose mode that preserves the needed information, and use last-image hold. Oblique and lateral views can markedly increase patient and staff dose; in a lateral view, staff should preferentially stand on the detector side rather than the tube side when duties permit.
People who remain in the controlled area must follow facility PPE and dosimetry requirements; the technologist is not automatically the radiation safety officer. Remove nonessential people and use ceiling-suspended/table-side shields or mobile barriers where available. Do not rely on generic kVp/mA ranges, one-distance scatter-dose claims, or a universal “within 100 cm” apron rule: output and scatter depend on system, patient, geometry, field size, pulse rate and dose mode.
Electronic magnification or a smaller field of view can increase dose rate on systems with automatic brightness/exposure control. Use magnification only when clinically needed. Documentation runs and acquisitions should use the lowest dose that provides the necessary information—not the “highest technique.” Monitor displayed dose metrics and communicate prolonged or high-dose events according to policy.
Safe mobile radiography is protocol-driven: identify the correct patient and examination, protect lines and life support, reproduce geometry when useful, collimate, use a validated technique chart, review the exposure indicator and image, disinfect equipment, and escalate urgent findings. The goal is not “one exposure at any cost”; it is the fewest exposures needed to answer the clinical question without accepting a nondiagnostic or unsafe result.
Try these ARRT-style multiple choice questions based on this article. Click an option to check your answer — correct answers turn green, wrong ones turn red.