List of top Medical Imaging Systems Questions asked in GATE BM

An X-ray beam of initial intensity I₀ of 70 keV imaging the chest is assumed to undergo attenuation through the muscle tissue for a thickness of 16 cm and further through the bone tissue for a thickness of 4 cm. The half value layer (HVL) thicknesses for the muscle and bone are 3.5 cm and 1.8 cm, respectively. The percentage of X-ray intensity transmitted through the body is ________.
Give your answer rounded off to 2 decimal places.

If a circular ultrasound transducer of radius a = 8 mm operating at a central frequency of 1 MHz has a pressure beam pattern in a medium as given below :
\(P(r,0) \propto\sin\frac{ka^2}{4r}\)
Here, k is the wave number, r is the axial distance from the center of aperture. The speed of sound in the medium is 1600 ms^-1.
The reduction in intensity between r = 8 cm and r = 16 cm is _______ dB. Give your answer as a positive quantity rounded off to two decimal places.

The X-ray attenuation coefficients as a function of photon energy for three materials are shown in the figure below. A tissue phantom containing these three materials is imaged at two different X-ray photon energies of 50 keV and 150 keV. When the developed X-ray film is viewed, which of the following statements is/are TRUE ?

A Doppler ultrasound transducer operating at 5 MHz gave maximum output frequency shift of 3 kHz. The velocity of sound in blood is 1500 m/s. If the probe was held at an angle of 45° to the direction of blood flow, the maximum velocity of blood flow through the artery is _______ m/s. (Give your answer rounded off to two decimal places.)

Which one of the following events is NOT typically encountered in diagnostic X-ray projection radiography ?