Radiography Exam Research & Evidence-Based Practice 2 — Questions and Answers

Question 1: Which level of evidence is considered highest in the evidence-based practice hierarchy?

Expert opinion
Case reports
Systematic reviews and meta-analyses of randomized controlled trials (Correct answer)
Cross-sectional observational studies

Correct answer: Systematic reviews and meta-analyses of randomized controlled trials

Systematic reviews and meta-analyses of multiple randomized controlled trials (RCTs) represent the highest level of evidence because they synthesize the best available research, reducing bias and increasing statistical power.

The evidence hierarchy (from highest to lowest) is: (1) Systematic reviews/meta-analyses of RCTs, (2) Individual RCTs, (3) Cohort studies, (4) Case-control studies, (5) Case series/case reports, (6) Expert opinion. In radiography research, RCTs may compare diagnostic accuracy of positioning techniques or dose reduction strategies. Meta-analyses pool data across studies, increasing statistical power to detect true effects. Radiographers should seek and apply the highest-level evidence available when making clinical decisions.

Question 2: In a radiography research study, a control group is used to:

Receive the experimental intervention
Provide a comparison baseline to evaluate the effect of the intervention (Correct answer)
Eliminate all variables from the study
Double the sample size automatically

Correct answer: Provide a comparison baseline to evaluate the effect of the intervention

A control group does not receive the experimental intervention (or receives a placebo/standard treatment), providing a baseline for comparison. This allows researchers to determine whether changes in the experimental group are due to the intervention.

The control group is essential for establishing causality. Without a control group, observed changes could be due to natural history, placebo effect, or unrelated factors. In radiography research, a control group might receive standard positioning while the experimental group uses a modified technique. Blinding (where possible) prevents bias. Randomization ensures the groups are comparable at baseline. The control group's outcome data is the benchmark against which the experimental group's results are measured.

Question 3: A radiographer reads a study claiming a new low-dose protocol reduces patient dose by 30% with no loss in diagnostic quality. Before adopting the protocol, the radiographer should evaluate:

Only the study's conclusion section
The study's methodology, sample size, peer review status, and applicability to their patient population (Correct answer)
Whether the protocol was used by a prestigious hospital
The lead author's credentials exclusively

Correct answer: The study's methodology, sample size, peer review status, and applicability to their patient population

Critical appraisal requires evaluating methodology (study design, sample size, controls), publication status (peer-reviewed), and external validity (applicability to one's own patients) — not just the conclusion or the source's prestige.

Evidence-based practice requires critical appraisal skills. Key questions for evaluating a radiography study include: Is the study design appropriate? Is the sample size adequate for statistical power? Were confounders controlled? Was there blinding? Is it peer-reviewed and published in a reputable journal? Was the patient population similar to yours (external validity)? Were the dose metrics and image quality assessments standardized? A 30% dose reduction claim requires rigorous validation before adoption to ensure patient safety is not compromised.

Question 4: The Institutional Review Board (IRB) in research protects:

The financial interests of the institution
The rights and welfare of human research participants (Correct answer)
The intellectual property of the research team
The institution from media scrutiny

Correct answer: The rights and welfare of human research participants

IRBs review and monitor research involving human subjects to ensure their rights (autonomy, informed consent) and welfare (minimized risk, justified benefit-to-risk ratio) are protected, in compliance with federal regulations.

The IRB (also called Research Ethics Board in Canada) is mandated by 45 CFR Part 46 (the Common Rule) for federally funded research and by FDA regulations for research involving drugs or devices. IRBs review: informed consent processes, risk-benefit ratios, subject selection equity, data privacy protections, and monitoring plans. In radiography, studies involving additional patient exposures for research purposes require IRB approval. Radiographers involved in research studies must understand their IRB-approved protocol and obtain proper consent.

Question 5: Which of the following best describes the concept of 'p-value' in research statistics?

The probability that the study hypothesis is true
The probability of obtaining the observed results (or more extreme) if the null hypothesis is true (Correct answer)
The percentage of patients who responded to the treatment
The power of the study to detect a true effect

Correct answer: The probability of obtaining the observed results (or more extreme) if the null hypothesis is true

The p-value is the probability of observing results at least as extreme as those found, assuming the null hypothesis is true. A p-value <0.05 is conventionally used to reject the null hypothesis and conclude statistical significance.

The p-value does NOT mean 'the probability the null hypothesis is true' (a common misinterpretation). It quantifies how surprising the observed data would be if the null hypothesis were true. A p-value of 0.03 means there is a 3% chance of seeing results this extreme by chance alone — leading to rejection of the null hypothesis at the 0.05 significance level. In radiography research, p<0.05 is the conventional threshold, but clinical significance (effect size, confidence intervals) is equally important and should accompany p-value reporting.

Question 6: When a radiographer applies a new evidence-based positioning technique, the process of integrating research evidence with clinical expertise and patient values is called:

Quality assurance
Evidence-based practice (EBP) (Correct answer)
Continuing medical education
Outcomes research

Correct answer: Evidence-based practice (EBP)

Evidence-based practice (EBP) is defined as the integration of best research evidence with clinical expertise and patient values to make clinical decisions. It is the framework for applying research findings in real-world radiography.

Sackett's definition of EBP (1996) incorporates three components: (1) best external evidence (published research), (2) individual clinical expertise (the practitioner's knowledge and experience), and (3) patient values and preferences. In radiography, EBP might involve: using published dose reduction protocols (evidence) adapted by the radiographer's technical skill (expertise) for a patient who has expressed concern about radiation exposure (patient values). EBP replaces tradition-based practice with a structured, critical approach to clinical decision-making.

Radiography Exam Research & Evidence-Based Practice 2

Which level of evidence is considered highest in the evidence-based practice hierarchy?