RRB Radiographer common mistakes
RRB Radiographer · Understand the traps and how to avoid them.
Increasing mAs instead of kVp when trying to penetrate a thicker or denser body part, then wondering why contrast collapses and patient dose rises.
The candidate memorised 'more mAs makes a darker image' but never separated beam quantity (mAs) from beam quality (kVp), so every exposure problem looks like an mAs problem.
What to do instead
Drill the 15% kVp rule: when thickness or density increases, raise kVp by about 15% and halve mAs to preserve receptor exposure. Build a one-page table of kVp/mAs changes for common projections and practise five exposure-adjustment scenarios before the exam.
Using adult exposure factors on a child or small adult, producing overexposure and repeated images because the first film looked 'too dark' and the candidate reduced only slightly.
Adult caseload habits dominate, and fear of underexposure makes candidates default to adult mAs rather than selecting a paediatric or low-dose protocol.
What to do instead
Memorise starting paediatric reductions: decrease mAs by roughly 30–50% and use the shortest exposure time possible; collimate tightly. Rehearse a three-step paediatric protocol (select small receptor, reduce mAs, increase kVp slightly if needed) and apply it to sample questions.
Mixing up occupational and public radiation dose limits, or whole-body and lens limits, in multiple-choice questions and choosing the largest familiar number.
Dose limits were memorised as isolated numbers without their categories, so the candidate recognises '20 mSv' or '1 mSv' but cannot attach the correct person, period or body part.
What to do instead
Create a category table: occupational whole-body, occupational lens, public whole-body, public lens, extremity, and student/apprentice limits, with the averaging period for each. Answer ten scenario questions where the first step is to identify who is exposed and which tissue is involved.
Treating CR, DR and film-screen as interchangeable in image-acquisition questions, selecting a processing step or artefact explanation that belongs to a different receptor type.
The candidate studied radiography in broad strokes and did not compare the physical image-forming chain, so 'cassette', 'plate', 'flat panel' and 'chemical bath' blur together.
What to do instead
Build a three-column comparison: film-screen (silver halide, chemical processing), CR (photostimulable phosphor plate, reader, laser), DR (flat-panel detector, direct/indirect conversion, no reader). For each, list one typical artefact and one resolution/dose implication, then test yourself by covering a column.
Skipping contrast-media safety screening and answering questions as if the only issue is injection technique, missing renal function, previous reaction, asthma and metformin considerations.
Candidates focus on positioning and machine settings because those are visual and technical, while patient-safety checklists feel like general nursing knowledge and get under-revised.
What to do instead
Memorise a pre-contrast checklist: renal function/eGFR, previous contrast reaction, asthma/allergy history, metformin and diabetes, pregnancy, and hydration. Practise five 'next best action' questions where the correct answer is to defer, premedicate or check a value rather than proceed.
Answering General Awareness questions from vague static-GK memory while ignoring railway-specific current affairs, budgets, appointments and recent schemes.
The candidate treats General Awareness as a fixed syllabus of old facts and does not maintain a monthly current-affairs log, so recent railway and national developments are unfamiliar.
What to do instead
Keep a one-page monthly log limited to railway current affairs, national schemes, appointments and sports awards. Revise it weekly and answer 20 current-affairs MCQs per week, marking any item older than six months for deletion from active revision.
Losing marks in arithmetic because units are dropped mid-calculation, especially in mAs, distance, inverse-square and dose calculations, so the final number is numerically plausible but dimensionally wrong.
The candidate writes numbers only and treats units as decoration, so a conversion from centimetres to metres or milligray to gray is missed without triggering an error signal.
What to do instead
Force dimensional analysis on every calculation: write the unit beside every number, cancel units, and check that the answer's unit matches what the question asks. Do ten mixed-unit problems where at least three require a conversion, and reject any answer whose unit is wrong before checking the arithmetic.
Spending four or five minutes on one arithmetic or reasoning question while leaving easier later questions unattempted.
The candidate equates effort with accuracy and cannot abandon a question after investing time, so sunk-cost thinking destroys the section score.
What to do instead
Adopt a 90-second rule: if the method is not clear after 90 seconds, mark and move on. In mocks, count how many questions are left blank at the end and treat each blank as a scoring failure; practise two full sections with a visible timer and a hard skip rule.
In non-verbal reasoning, choosing a mirror image as a water image or missing a rotation because only one feature of the figure was checked.
Visual questions are answered by a quick overall impression rather than a systematic feature-by-feature comparison, and the candidate does not distinguish reflection from rotation.
What to do instead
Use a fixed checklist for every figure: orientation, handedness, position of a marked dot, and whether the change is a flip or a rotation. For water images, check vertical inversion; for mirror images, check horizontal reversal. Practise ten pairs and write the rule that distinguishes them before choosing.
Answering syllogism questions with real-world knowledge instead of treating the statements as the only truth, or drawing no Venn diagram and guessing the conclusion.
Everyday reasoning feels faster than formal logic, so the candidate accepts conclusions that are true in life but not entailed by the given statements.
What to do instead
For every syllogism, draw the minimum Venn diagram and test each conclusion against all possible arrangements, including the 'some' and 'no' cases. Memorise the standard conclusion rules and practise ten items where the real-world answer is deliberately wrong.