(a)(i)State what is meant by contrast in an X-ray image.
2022 · Specimen · 9702/04 | Q10
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Available practice: 77 of 100 marks. Parts 1(b), 4(b)(i), 4(c), 6(a)(ii), 6(b)(ii), 7(a)(i), 7(a)(ii), 9(b)(i), 9(c), 10(b)(ii) await marking support. Scores cover available parts only.
A parallel beam of X-ray radiation is incident, separately, on samples of bone and of muscle.
Data for the thickness x of the samples of bone and of muscle, together with the linear attenuation coefficients μ of the radiation in bone and in muscle, are given in Table 10.1: bone x = 1.5 cm, μ = 2.9 cm⁻¹; muscle x = 4.0 cm, μ = 0.95 cm⁻¹.
(a)(ii)Calculate the ratio (intensity of radiation transmitted through the bone) / (intensity of radiation transmitted through the muscle).
(b)(i)Explain how ultrasound pulses are used to obtain diagnostic information about internal body structures in medical diagnosis.
Two media have specific acoustic impedances Z₁ and Z₂.
State the approximate value of the intensity reflection coefficient at the boundary between the two media when:
• Z₁ is almost equal to Z₂
(b)(iii)• Z₁ is very different from Z₂.
9702/04/SP/22Cambridge International AS & A Level Physics 9702 · Specimen 2022 · Paper 4 · Question 10