49,

51.

53.

55.

56.

Regarding original EMI scanner, which of the following is not true ?

(ಗ) designed specifically for evaluation of brain

(B) only 2 detectors were used

(C) head was enclosed in water bath during scanning

(D) rigid scanner gantry maintained the relative position of the X-ray tube வாம்‌ detectors

Regarding CT scan, which of the following is not true ?

(ക) detectors are fixed in 4™ generation scanners

(8) fan beam of X-rays was introduced in 2 generation scanners

(9) 1१ 2 generation scanners, number of detectors were as many as 30
(D) Rotate-rotate scanner was introduced in 1978

Regarding CT scan, which of the follawing is not true ?

(வ) X-ray beam is collimated entirely at the level of detectors

(ए) each detector has its collimator

(0) collimator regulates the slice thickness

(D) collimator at the detector level is the sole means of contrelling scatter radiation

Regarding Scintillation Crystal detectors, which of the following is not true ?

(A) 1 generation of CT scan used thallium activated Na I crystals with silicon photodiodes
(ए) scintillation Crystal will produce light when ionizing radiation reaches them

{(€) combination of scintillation material and light detector is called scintillation detector
(D) detector cross talk decreases resolution

Regarding resolution of CT scan, which of the following is not true ?

(^) resolution is expressed in line pairs/mm in CT

(B) detector size influences spatial resolution

(८) increasing the matrix size will improve high contrast spatial resolution

(12) improvement of both contrast resolution and spatial resolution will require increased patient
dose

Regarding CT artifacts, which of the following is not true ?
(A) motion artifacts are reduced by using faster scan

(18) streak artifacts occur at the edge of high contrast objects
(C) ring artifacts are common in rotate-rotate geometry

(D) तप artifacts of head is due to miscaliberation of detector

Regarding Radiation units, which of the following is not true ?

(A) Remis a unit of absorbed dose

(B) As measure of exposure, Roentgen is Independent of area of field size
(८) 1Gray is 100 Rads

(D) 1Sievert is 100 Rems

Regarding Half value layer, which of the following is not true ?

(ക) is expressed in mm of lead and cm of concrete

(0) beam with HVL of 0.2 mm lead is more penetrating than a beam with HVL of 0.1 mm lead

)© HVL is the thickness of specific substance that when introduced into the path of beam
reduces exposure rate by one half

(೧) MV for 100 kVp X-rays is 0.24 mm lead

9 153/2014
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