RRB Radiographer flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

mAs

Milliampere-seconds; product of tube current and exposure time; controls the number of X-ray photons produced and hence receptor exposure without altering beam penetration.

kVp

Peak kilovoltage; controls photon energy and penetration and therefore subject contrast; higher kVp produces more scatter and lower contrast.

Inverse square law

X-ray intensity is inversely proportional to the square of the distance from the source; doubling FFD reduces intensity to one quarter, so mAs must be quadrupled.

Grid ratio

Ratio of lead strip height to interspace width; higher ratios remove more scatter but require greater mAs and increase patient dose.

Photoelectric effect

An X-ray photon is absorbed completely, ejecting an inner-shell electron; dominant at low kVp and high atomic number, giving high contrast for bone and barium.

Compton scattering

An X-ray photon interacts with an outer-shell electron, loses energy and changes direction; dominant at higher kVp and causes scatter fog that lowers contrast.

ALARA

As Low As Reasonably Achievable; dose-reduction principle using time, distance and shielding while still obtaining the diagnostic information required.

Occupational dose limit

ICRP limit: 20 mSv per year averaged over five years, never more than 50 mSv in one year; public limit is 1 mSv per year.

Barium sulfate

Insoluble positive contrast agent used for gastrointestinal studies; contraindicated when perforation is suspected because leakage causes peritonitis.

Automatic processor

Processor that develops, fixes, washes and dries film automatically; developer is held near 35 degrees C with about a 90-second cycle.

Radiographic density

Degree of blackening of a processed radiograph; increased by higher mAs, developer temperature or time; excessive density obscures detail.

First Indian passenger train

Ran between Bori Bunder in Mumbai and Thane on 16 April 1853, covering about 34 km; hauled by three locomotives, including Sahib.

Railway Board

Apex policy body of Indian Railways, chaired by the Chairman and CEO; headquartered in New Delhi; railway zones are headed by General Managers.

RDSO

Research Designs and Standards Organisation, located at Lucknow; technical adviser and standards body for Indian Railways rolling stock and infrastructure.

Vande Bharat Express

Indigenously designed semi-high-speed train set with a designed speed of 180 km/h; the first service began in 2019 between Delhi and Varanasi.

Bharat Ratna

Highest civilian award of India, instituted in 1954; recognises exceptional service in art, literature, science, public service or sports.

Article 32

Constitutional right to remedies; allows the Supreme Court to issue writs for enforcement of Fundamental Rights; called the heart and soul of the Constitution by Ambedkar.

Tropic of Cancer states

Passes through eight Indian states: Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura and Mizoram.

Simple interest formula

SI = (P x R x T)/100, where P is principal, R the annual rate percent and T the time in years; amount equals P + SI.

Compound interest formula

A = P(1 + R/100)^T; compound interest equals A - P; more frequent compounding increases the effective annual rate.

Effective two-year CI rate

For annual compounding, the two-year effective rate is 2R + R^2/100 percent; for example, 10% per year becomes 21% over two years.

Speed conversion

Multiply km/h by 5/18 to get m/s; multiply m/s by 18/5 to get km/h; convert before applying distance = speed x time.

Combined work time

If A alone takes a days and B alone takes b days, working together they finish the job in ab/(a + b) days.

Train crossing platform

Time = (train length + platform length) / train speed; convert length to metres and speed to m/s before dividing.

Weighted average

Sum of each value multiplied by its weight, divided by total weight; used when combining groups of unequal size.

EJOTY code

Mnemonic for letter positions: E=5, J=10, O=15, T=20, Y=25; speeds up coding-decoding and alphabet-series questions.

Syllogism 'some'

'Some A are B' is reversible and means at least one A is B; it does not imply 'some A are not B' or 'all A are B'.

Blood relation tree

Draw separate branches for each generation; vertical lines show parent-child links, horizontal lines marriage; never assume gender from names.

Clock angle formula

Angle between hands = |30H - 5.5M| degrees, where H is hour and M is minutes; if the result exceeds 180 degrees, subtract it from 360.

Odd days calendar

Remainder when total days are divided by 7; an ordinary year has 1 odd day, a leap year 2; 100 years have 5, 200 have 3, 300 have 1, 400 have 0.

Standard dice rule

In a standard die opposite faces sum to 7; faces visible together cannot be opposite, which eliminates impossible orientations.

Circular seating left-right

When people face the centre, left is clockwise and right anticlockwise; reverse these directions when they face outward.