RRB Radiographer key terms

A vacuum tube containing a heated cathode filament that emits electrons and an anode target that they strike after acceleration by high voltage. The interaction produces X-rays used for imaging.

The maximum voltage applied across an X-ray tube during an exposure. Higher kVp gives a more penetrating beam, reduces subject contrast and generally lowers patient dose for the same receptor exposure.

The product of tube current in milliamperes and exposure time in seconds. It sets the total number of X-ray photons produced and hence the receptor exposure, while kVp sets their energy.

An abbreviation of As Low As Reasonably Achievable, the radiation-protection principle that every exposure should use the smallest dose that still gives the required diagnostic information, taking cost and practicality into account.

A flat device of thin lead strips separated by radiolucent material, placed between the patient and the image receptor. It absorbs off-axis scattered radiation and so improves image contrast, at the cost of higher dose.

Adjustable lead shutters at the tube port that shape the X-ray beam to the region of interest. Restricting the field reduces scatter and lowers the dose to surrounding tissue.

The distance measured from the X-ray tube's focal spot to the image receptor. Increasing SID reduces magnification and, by the inverse-square law, lowers beam intensity at the receptor.

The small area on the anode where electrons strike and X-rays are generated. A small focal spot produces sharper images, while a large one withstands more heat and permits higher tube currents.

The component that records the X-ray pattern emerging from the patient, such as a photostimulable phosphor plate in computed radiography or a flat-panel detector in digital radiography.

A substance given to a patient to increase the difference in X-ray attenuation between body structures, for example iodine-based agents for angiography or barium sulphate for gastrointestinal examinations.

A dynamic imaging technique using a continuous or pulsed X-ray beam and a monitor display, allowing real-time observation of moving structures and the passage of contrast material.

A number on a scale used in computed tomography that expresses how strongly a tissue attenuates X-rays compared with water, which is zero; air is about minus one thousand.

Picture Archiving and Communication System: a computer network that stores, retrieves and distributes digital medical images so clinicians can view them at many locations instead of handling films.

Digital Imaging and Communications in Medicine: the international standard that defines image file format and network communication, letting scanners, workstations and archives from different manufacturers exchange studies.

The SI unit of equivalent and effective dose, which weights absorbed dose for the biological harm of the radiation type and the sensitivity of the tissues exposed; used in radiation protection.

Basic rights such as equality, freedom of speech, life and personal liberty, guaranteed to citizens by Part III of the Indian Constitution and enforceable in courts through writs.

Guidelines in Part IV of the Indian Constitution that direct the state to promote social and economic welfare and a welfare society. They are not directly enforceable in courts.

The system of rural local self-government at village, intermediate and district levels, given constitutional status by the 73rd Amendment Act of 1992.

The lower house of India's Parliament, whose members are elected directly by voters from constituencies and which is responsible for money bills and confidence in the government.

The total market value of all final goods and services produced within a country's borders in a given period, usually a year, and a standard measure of economic size.

The seasonal reversal of prevailing winds that brings most of India's annual rainfall, chiefly the south-west monsoon from June to September, and strongly influences agriculture and water resources.

A way of expressing a fraction with a denominator of one hundred. A value of x per cent means x parts in every hundred and allows quantities with different bases to be compared.

A comparison of two quantities of the same kind by division, written as a:b. It states how many times one quantity contains the other and is used in proportion problems.

The sum of a set of values divided by the number of values. It gives a single central value that represents the whole data set in many arithmetic problems.

Interest calculated only on the original principal for the whole period, using the formula principal multiplied by rate multiplied by time and divided by one hundred.

Interest calculated on the principal plus interest already earned, so that the amount grows faster than with simple interest and depends on how often interest is compounded.

Business arithmetic in which profit is selling price minus cost price and loss is cost price minus selling price; answers are usually asked as a percentage of the cost price.

A group of problems comparing the rates at which people or machines finish a task, usually by taking the whole work as one unit and adding or subtracting rates.

A method in which the value of one unit is found first by division and then multiplied by the required number of units to obtain the answer.

A reasoning question that gives one pair of related items and asks you to complete a second pair using the same relationship, such as worker to workplace or word to synonym.

A sequence of numbers generated by a hidden rule, such as a constant difference, increasing increments or alternating operations, in which the missing next term must be found.

A puzzle in which letters, words or digits are converted into a code using a fixed rule, and the candidate must apply the same rule to decode or encode another word.

Verbal problems that describe how certain people are related and ask for the relationship between two of them; they are usually solved by drawing a family tree.

Problems in which a person moves through given turns and distances and the candidate must work out the final direction, or the straight-line distance, from the starting point.

A deductive reasoning task with two or more given premises and a conclusion, where the candidate decides whether the conclusion necessarily follows from the premises.

A diagram of overlapping circles representing sets, used to show shared and unshared members and to solve questions about groups with common characteristics.

A puzzle that places a set of people in a row or around a circle under given conditions, from which their exact positions must be logically deduced.