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newSchoolWorks.com › VoTechWorks › Health & Personal Services › Limited X-Ray / Radiologic Technology › Clinical Practicum: Supervised Radiographic Practice › Lesson 2
HLT-RADI64-10 · Lesson 2 · 300 clock hours · practice

Competency-Based Radiographic Positioning — Core Projections

Objective. The student independently performs the full set of required radiographic projections — including chest, spine, extremities, and abdomen — meeting ARRT competency criteria for positioning accuracy, exposure technique, radiation protection, and image quality on live patients.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a licensed clinician in the field or by a certification or approval body. It is a study draft and may contain errors. Do not use it to make decisions about any patient or medication. Always follow your instructor, your supervising professional, and current official references and regulations.

VoTechWorks program approval and accreditation are still in progress. Credentials are issued only by the certifying bodies named in each program, after their own exams.

What Competency-Based Practice Means

In clinical radiography, a competency check-off is not simply completing a task — it is a structured demonstration that you can position a patient correctly, select appropriate exposure techniques, apply radiation protection, and produce a diagnostically acceptable image, all independently. The ARRT defines specific projections that must be demonstrated before a candidate sits for certification. Your program has mapped those requirements onto a standardized check-off form with a 5-point rubric covering positioning landmarks, collimation, source-to-image distance (SID), exposure indicator, and overall image acceptability. A score of 4 or 5 on every item is the threshold for passing.

Core Projection Groups

Chest: The PA and lateral chest are the most frequently performed projections in most clinical sites. For the PA projection, the patient stands (or is seated erect when standing is impossible) with the posterior thorax facing you, hands on hips, elbows rotated forward. Confirm the chin is elevated off the collimator field, the MSP is centered to the IR, and the shoulders are rolled forward to move the scapulae out of the lung fields. SID is typically 72 inches for chest to reduce magnification of the cardiac silhouette. Expose on full inspiration. The lateral chest requires the patient to raise both arms above the head or hold a support bar; the midcoronal plane is centered to the IR. Both projections must show the entire lung fields including costophrenic angles.

Spine: Lumbar, thoracic, and cervical spine series are common limited-scope projections. Collimation to the spine is critical — tight to the area of interest, never to the full field. For AP lumbar spine, center to L3 (level of the iliac crests). Oblique lumbars demonstrate the zygapophyseal joints ("Scotty dog" sign). Lateral lumbar must show the lumbosacral junction. For cervical spine, use appropriate SID and confirm the patient's chin is positioned so it does not overlap C1 on the AP open-mouth view.

Extremities: Upper and lower extremity projections include at minimum two projections at 90 degrees to each other for most joints. Always include the joint proximal and distal to a long-bone fracture site. Confirm the part is parallel to the IR and the central ray is perpendicular (or angled as required). Fingers and toes require the part against the IR surface; small foam positioning aids prevent rotation.

Abdomen: The AP supine abdomen (KUB) and upright abdomen are the primary projections. For the KUB, center to the level of the iliac crests with the lower margin of the IR at the pubic symphysis; on tall patients confirm the diaphragm is included on a second exposure if needed. Expose on suspended expiration for abdominal projections.

Radiation Protection at Every Step

Radiation protection is not optional and is weighted in your rubric. Before every exposure:

Wear your personal dosimeter at all clinical shifts. If a reading seems unusually high, report it to your clinical supervisor immediately.

Direct vs. Indirect Supervision

ARRT and most state regulations require that student radiographers perform each competency projection first under direct supervision — the qualified radiographer reviews the request, evaluates the patient's condition, is present in the room or immediately available during the procedure, and reviews the image before release. After demonstrating competence on a projection, you may perform subsequent identical projections under indirect supervision — the qualified radiographer is immediately available but need not be present in the room. You must never perform an unsupervised repeat exposure of an image that is not of diagnostic quality on an uncomitted patient without a qualified radiographer present, regardless of your experience level.

Image Critique and Repeat Analysis

After each projection, conduct a structured critique. Ask: What anatomic structures are demonstrated? Are they within the collimated field? Is there rotation? Is the exposure indicator within the acceptable range for the IR system in use (DR or CR)? Is there motion blur? Would a radiologist be able to make a diagnosis from this image? If a repeat is clinically justified, state the specific reason — positioning error, exposure error, motion, artifact, or patient-related factor — and document it with the appropriate reason code.

Track your personal repeat rate weekly. A repeat rate that consistently exceeds the departmental benchmark signals a pattern that needs correction. Monthly review with your supervising technologist identifies whether the pattern is positioning, technique selection, or communication with the patient. Document one concrete corrective action per identified pattern in your clinical log.

Passing the Competency Check-Off

Every projection must score ≥ 4 out of 5 on the rubric and carry your supervisor's signature to count as complete. Any projection scoring 3 or below must be repeated in full — there is no partial credit. You may not advance to indirect supervision on a projection until the direct-supervision competency is signed off. Complete the program's required list before your ARRT application deadline; incomplete competencies delay eligibility.

Key terms10

Competency check-offA formal, supervised demonstration that a student can perform a specific radiographic projection independently, scored against a standardized rubric and signed by a qualified technologist.
ALARAAs Low As Reasonably Achievable — the radiation protection principle requiring that exposure to ionizing radiation be kept as low as possible while still producing a diagnostic image.
Direct supervisionA supervision level in which a qualified radiographer reviews the request, evaluates the patient, is present or immediately available during the procedure, and reviews the image before release.
Indirect supervisionA supervision level in which a qualified radiographer is immediately available to assist but need not be physically present in the room during the exposure.
Source-to-image distance (SID)The measured distance from the focal spot of the X-ray tube to the image receptor; standardized SID values (commonly 40 or 72 inches) affect image magnification and exposure.
CollimationThe restriction of the X-ray beam to the area of clinical interest using adjustable lead shutters; reduces patient dose and improves image contrast by limiting scatter radiation.
Exposure indicatorA numeric value displayed by a digital radiographic system (DR or CR) that reflects the amount of radiation reaching the image receptor; used to evaluate whether the exposure technique was appropriate.
Repeat rateThe percentage of radiographic exposures that must be retaken because the original image was not diagnostically acceptable; tracked as a quality improvement and dose-reduction metric.
Gonadal shieldingLead shielding placed over the reproductive organs to reduce radiation dose to sensitive tissues, applied when doing so does not obscure the anatomy being imaged.
Central rayThe center of the X-ray beam, directed to a specific anatomic landmark for each projection to ensure correct image geometry and minimize distortion.

Worked examples4

1. You are setting up for a PA chest on a 68-inch-tall adult patient standing at the upright Bucky. The department protocol calls for 72-inch SID. The wall Bucky is mounted with its center at 56 inches from the floor. Should the IR center be adjusted, and to which vertebral level should you center the central ray for a PA chest?
  1. Step 1: Confirm SID. Measure from the focal spot indicator on the tube to the front surface of the IR; adjust the tube-column to achieve 72 inches. The wall Bucky position itself does not change SID — tube-to-IR distance does.
  2. Step 2: Identify the correct centering level. For a PA chest the central ray is directed horizontally to the level of T7 (approximately the inferior angle of the scapulae), which places the collimated field to include both apices and both costophrenic angles.
  3. Step 3: Verify IR height. Position the top of the IR approximately 1.5 to 2 inches above the patient's shoulders so the apices are included; the costophrenic angles should fall within the lower margin.
  4. Step 4: Collimate. Open the shutters to include the entire thoracic cage from apex to costophrenic angle laterally; do not include unnecessary tissue beyond the lung fields.
Answer: Set tube-to-IR distance to 72 inches. Center the central ray horizontally to T7 (inferior angle of the scapulae). Position the IR top 1.5–2 inches above the shoulders. Collimate to the thoracic cage.
2. For an AP lumbar spine projection on a standard adult, you need to center the central ray to L3. A common surface landmark places L3 at the level of the iliac crests. The IR is 14 × 17 inches placed lengthwise. Describe how you confirm the entire lumbar spine including L5–S1 will be included on the image.
  1. Step 1: Palpate the iliac crests bilaterally and mark the midpoint; this corresponds approximately to L3–L4. Direct the central ray perpendicularly to this level at the midline (MSP).
  2. Step 2: Calculate field coverage. A 17-inch IR centered at L3 extends roughly 8.5 inches superiorly (toward T12) and 8.5 inches inferiorly (toward the upper sacrum), which should include L1 through S1 in most adults.
  3. Step 3: For tall patients, if L5–S1 appears to be cut off at the inferior margin, lower the IR slightly so the central ray is centered closer to L4 and the inferior field edge includes the lumbosacral junction.
  4. Step 4: Collimate to the spine — approximately the width of the lumbar vertebrae — to reduce scatter and improve image quality. Confirm both iliac wings are symmetrical on the resulting image to check for rotation.
Answer: Center to the iliac crests (L3) with the CR perpendicular to the MSP. A 17-inch IR covers approximately L1–S1 in most adults. For tall patients, shift the IR inferiorly to ensure the lumbosacral junction is included. Tight collimation reduces scatter and confirms positioning.
3. During a shift you take 42 total exposures and have to repeat 4 images. What is your repeat rate for that shift, expressed as a percentage?
  1. Step 1: Identify the number of repeated images: 4.
  2. Step 2: Identify the total number of exposures, including the repeats: 42.
  3. Step 3: Apply the repeat-rate formula: Repeat rate = (number of repeated images ÷ total exposures) × 100.
  4. Step 4: Calculate: (4 ÷ 42) × 100 = 9.52%, rounded to approximately 9.5%.
Answer: Your repeat rate for that shift is approximately 9.5%. Document each repeat with a reason code and discuss the pattern with your supervising technologist at your next monthly review.
4. You are performing an AP knee on a patient lying supine. The protocol calls for a 10-degree cephalic angle on the central ray. The IR is placed flat under the knee. The femoral epicondyles are 17 inches from the tabletop surface. Describe the positioning steps to direct the CR correctly and explain why the angle is used.
  1. Step 1: Position the patient supine with the leg extended and the knee centered to the IR. Ensure no rotation by confirming the femoral epicondyles are equidistant from the tabletop — you can palpate them to check.
  2. Step 2: Locate the centering point: the central ray is directed to the patellar apex (inferior pole of the patella) or 0.5 inch inferior to the apex, which corresponds to the joint space in most adults.
  3. Step 3: Angle the tube 5–7 degrees cephalad (some protocols use up to 10 degrees, depending on the angle of the tibial plateau); this angle opens the joint space and prevents the anterior tibial margin from obscuring the joint.
  4. Step 4: Confirm SID per department protocol (commonly 40 inches for tabletop extremity work). Collimate to the knee joint, including distal femur and proximal tibia. Expose using appropriate technique for soft-tissue and bony detail.
Answer: Position the leg without rotation, center the CR to the patellar apex, apply the specified cephalic angle to open the joint space, collimate tightly, and expose at the protocol SID. The cephalic angle compensates for the natural slope of the tibial plateau so the joint space is projected open on the image.
In class: Perform each required ARRT competency projection at least once under direct supervision and once under indirect supervision, completing the program's standardized competency check-off form for every projection; the supervising technologist scores positioning landmarks, collimation, SID, exposure indicator, and image acceptability on a 5-point rubric. · After each completed image, conduct a structured verbal image critique with the supervising technologist — identifying anatomic structures demonstrated, acceptable versus unacceptable image quality criteria, and the reason any repeat would be clinically justified — and record findings in the clinical log. · Track personal repeat-rate data weekly by logging every repeat image with the reason code (positioning, exposure, motion, artifact, or patient) on a tally sheet; review trends with the supervising technologist monthly and document one corrective action per identified pattern.
Materials: Radiographic units (DR/CR), positioning sponges, sandbags, lead aprons, gonadal shields, thyroid shields, tape measure, clinical competency check-off forms, clinical log, personal dosimeter, Bontrager & Lampignano positioning reference
Check: Student completes 100% of program-required competency projections with a rubric score of ≥ 4 out of 5 on each; personal repeat rate documented and discussed; any projection scoring below 4 must be repeated until passing — supervisor signature required on each passed competency form

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

Patient Care and Education
1. A student is about to perform an AP pelvis projection for the first time on a live patient. According to ARRT supervision standards, which level of supervision is required?
Image Production
2. During a PA chest projection, the patient's scapulae are superimposed over the lateral lung fields on the resulting image. Which positioning error most likely caused this finding?
Image Production
3. A student logs 3 repeat exposures out of 30 total exposures in one day. What is the student's repeat rate?
Radiation Protection
4. Which of the following actions BEST demonstrates the ALARA principle during radiographic positioning?
Image Production
5. On an AP lumbar spine image, the spinous processes are not centered between the pedicles on successive vertebrae. What does this finding most likely indicate?
Patient Care and Education
6. A student completes a competency check-off for the lateral chest and receives a rubric score of 3 out of 5 because the costophrenic angles were clipped. What is the correct next step according to program policy?
Radiation Protection
7. When is it appropriate to perform a repeat exposure of an unacceptable image WITHOUT a qualified radiographer being directly present?
Image Production
8. A student notices that over the past month, the majority of their repeat images are coded as 'positioning' errors specifically on shoulder projections. What is the MOST appropriate action based on clinical log review?
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