An adolescent with suspected idiopathic scoliosis arrives with a back brace, a pediatrician order for erect PA and lateral full-spine views, and no history of trauma. The supervisor stresses gonadal shielding, breathing technique, and inclusion from C7 to sacrum without rotation. Which scoliosis series approach best meets positioning and shielding requirements?

The correct approach reflects adolescent scoliosis protocol because erect PA minimizes breast dose while displaying weight-bearing curvature for Cobb measurement, lateral adds sagittal alignment, relaxed arms avoid induced rotation, suspended respiration freezes motion for sharp endplates, and tight collimation with patient shielding applied per facility policy protects tissue (current AAPM and NCRP guidance favors optimized technique and collimation over routine contact shielding, and a shield must never obscure the spine or force a repeat) while preserving C7 to sacrum inclusion with symmetric pedicles and centered spinous processes. The erect AP variant fails projection principle because the anterior entry beam markedly increases breast dose and magnification in an adolescent, contradicting the PA order and ALARA despite correct posture, breathing, and shielding. The supine variant fails biomechanical principle because recumbency unloads the spine and understates the true curve, so it cannot substitute for erect weight-bearing evaluation despite correct PA direction, breathing, and shielding. The continuous-breathing variant fails motion-control principle because rib and diaphragmatic movement during long exposure blurs landmarks needed for measurement, whereas suspension ensures clarity. An exam caveat is that distractors often differ by only one word such as AP versus PA or supine versus erect, so verify every qualifier. A practical check is to confirm symmetric clavicles and iliac wings, C7 to sacrum included, shielding clear of anatomy, and exposure made on suspension.