2.1 Pre-Scan Assessment — Scheduling, History, Lab Values & Communication

Why Pre-Scan Assessment Is High-Yield

Patient Assessment and Preparation is the densest lettered subcategory on the ARRT Computed Tomography (CT) content outline: fourteen numbered items live inside Patient Care's 21 scored questions (12.7% of the 165-question exam). Because CT technologists rarely have more than a few minutes of direct contact with a patient before the table starts moving, almost everything that prevents a wasted appointment, a repeat scan, or a patient-safety event happens in this pre-scan window — scheduling, chart review, patient history, and lab-value screening. On the exam, questions in this cluster are usually written as "what should the technologist do before scanning" scenarios, and the correct answer is almost always about gathering information and escalating appropriately, not making a final clinical judgment call that belongs to the radiologist or ordering provider.

Scheduling and Screening

Scheduling and screening (item 1) is the first place CT-specific decisions get made — often by phone or an electronic questionnaire before the patient ever arrives. A complete pre-scan screen confirms:

• The ordered exam matches the clinical indication (a screening call revealing symptoms suggesting pulmonary embolism should trigger confirmation that a CT pulmonary angiogram, not a routine chest CT, was actually ordered).
• Contrast plan and IV access needs — contrast-enhanced studies require adequate venous access and enough appointment time for line placement.
• Oral contrast prep timing — a positive oral contrast abdomen/pelvis protocol typically requires the patient to start drinking contrast 60–90 minutes before the scan.
• Weight and body habitus against the CT table's rated weight limit (commonly 450–680 lb depending on manufacturer) and the gantry aperture.
• Claustrophobia or inability to lie still or breath-hold, which may require anti-anxiety premedication (Section 2.2) or protocol adjustment.
• Known allergies, pregnancy status, and renal function, screened at scheduling so any needed labs or physician consultation happen before the appointment, not during it.

A technologist who skips scheduling-level screening pushes every one of these problems into the scan room, where they become urgent instead of routine.

Patient History

Patient history (item 2) goes beyond the ordering diagnosis. On arrival, the technologist confirms identity using two identifiers (name and date of birth, matched to the order), reviews the chief complaint driving the exam, and checks for history that changes protocol — for example, a patient with a prior nephrectomy needs the radiologist to account for having only one kidney before a multiphase renal CT, and a patient with a known iodinated contrast reaction changes the entire contrast pathway (Chapter 3). Prior imaging should be identified for comparison whenever it exists, since radiologists frequently need a baseline study to assess interval change.

Interpersonal Communication

Item 3, interpersonal communication, is explicitly scoped on the outline to the patient care team and provider — not to the patient (that is patient education, Section 2.2), but to the technologist's role inside the care team. Concretely: clarifying an ambiguous or incomplete order with the ordering provider, relaying an unexpected critical lab value or vital sign change to the radiologist, and communicating relevant history (a Foley catheter, isolation status) during a patient handoff. Exam questions test whether the "next best step" is escalation to the right team member, not an independent clinical decision outside the technologist's scope.

Lab Values

Item 4 splits into renal function (4.a) and other lab values (4.b) — the most numerically testable item in the subcategory.

Renal function deserves numeric fluency. Estimated GFR stages chronic kidney disease (CKD): G1 ≥90 (normal), G2 60–89 (mildly reduced), G3a 45–59, G3b 30–44 (moderately to severely reduced), G4 15–29 (severely reduced), and G5 <15 mL/min/1.73 m² (kidney failure). An eGFR below roughly 30 is the value CT departments treat as substantially increased risk for contrast-induced nephropathy, typically prompting a documented renal-function review and possible radiologist consultation before proceeding — the specific contrast decision algorithm is covered in Chapter 3; here, the tested skill is recognizing and flagging the lab value, not making the final call.

Realistic Exam Scenario

A CT department's scheduling desk receives a next-day request for a contrast-enhanced CT urogram on a 70-year-old patient with type 2 diabetes managed on metformin. The chart shows no renal function lab within the past six months. The correct action at the scheduling/screening stage is to order a current eGFR or creatinine before the appointment, so the department has the information needed to make a safe contrast decision on the day of the scan — not to cancel the study outright, and not to wait until the patient is on the table to discover the missing data.

Common Traps

• Confusing the technologist's screening role (gather and flag) with the radiologist's clinical decision (whether to proceed, modify, or hold). ARRT scenario questions usually want "notify the radiologist" or "obtain a current lab," not a unilateral decision.
• Mixing up direction: a lower eGFR means worse kidney function, while a higher creatinine means worse kidney function — they move in opposite directions.
• Forgetting that "other" lab values (D-dimer, LFTs, INR, PT/PTT, WBC, hCG, Hgb) are each individually testable, not just a generic "check the labs" concept.