AQA A Level Physics Paper 3 Section B: Medical physics June 2022 question paper 7408/3BB

An eye condition is corrected using a +4.0D lens.

Which eye condition could be corrected by using this lens? Tick () one box.

Calculate the magnification produced by the +4.0D lens when viewing an object 75 cm from this lens.

Figure 1 shows a diagram of an eye.

State the name and primary optical function of X, Y and Z.

Primary optical function of X

Primary optical function of Y

Primary optical function of Z

An X-ray image is to be made of a broken bone. The image can be formed on

• photographic film

• a flat panel (FTP) detector or

• an intensifying screen using fluoroscopic image intensification.

State and explain which one of these detection methods should be used in this situation. Go on to discuss why the other two methods are less suitable.

Figure 2 shows an X-ray of a broken bone.

mean diameter of bone = 0.040 m

intensity of incident X-rays = 0.013 W m⁻²

exposure time of X-ray = 0.80 s

linear attenuation coefficient of bone = 58.3 m⁻¹

Calculate an estimate for the X-ray energy that is absorbed by the bone.

State two reasons why the estimate of energy absorption in Question 02.2 may be greater than the actual value.

Sketch an equal loudness curve on Figure 3 showing the normal response of a healthy ear. Annotate the frequency axis with an appropriate scale.

Describe the procedure used to gather the data for an equal loudness curve.

Calculate the intensity of a sound that produces an intensity level of 30 dB.

A patient has calcium kidney stones. Three types of scan are available to investigate the condition:

• a magnetic resonance (MR) scan

• a CT scan

• an ultrasound scan.

Calcium kidney stones contain no water and appear similar to bone in each of the scans.

Discuss the advantages and disadvantages of each option. In your answer you should

• refer to the relevant quality of the image obtained from each scan

• identify other factors that should be considered

• justify the type of scan you would recommend.

State the purpose of the magnetic field in a magnetic resonance scanner.

Describe the role of the radio frequency pulses in a magnetic resonance scanner.