X-rays and ultrasound

Transcription

1 X-rays and ultrasound P3 6 minutes 6 marks Page of 23

2 Q. The picture shows a horse being prepared for an X-ray. The person who will take the X-ray and the person holding the horse are wearing special aprons. These aprons have a lead lining. Explain why the lead lining is important. To gain full marks in this question you should write your ideas in good English. Put them into a sensible order and use the correct scientific words (Total 3 marks) Q2. (a) The diagram shows four sound waves, J, K, L and M, represented on an oscilloscope screen. They are all drawn to the same scale. J K L M (i) Which two of the waves have the same amplitude? Wave... and wave... () Page 2 of 23

3 Which of the waves would sound the loudest? Wave... () (iii) Only one of the waves is an ultrasound wave. Which one is the ultrasound wave? Wave... Give a reason for your answer. (b) The diagram shows ultrasound being used to examine the ligament inside the leg of a horse. Use words from the box to complete the following sentences. computer detector transmitter The... sends pulses of ultrasound into the leg. When the ultrasound meets the ligament, some is reflected back to the... The reflected pulses are converted by a... into an image that can be seen on the screen. (Total 6 marks) Page 3 of 23

4 Q3. Both X-ray machines and CT scanners are used to produce images of the body. (a) The diagram shows an X-ray photograph of a broken leg. Before switching on the X-ray machine, the radiographer goes behind a screen. Explain why the radiographer does this. (3) (b) The following is an extract from a newspaper article. X-rays cause 700 new cancers each year in the U.K. Each year there are about new cancer cases in the UK, of which, about 700 may be due to the use of X-rays to diagnose illness. The article was reporting on a scientific research project first published in a medical journal. What evidence would the scientists have collected to come to the conclusion that X-rays can cause cancer? Page 4 of 23

5 (c) Explain the advantage of a CT scan compared to an X-ray. (Total 7 marks) Page 5 of 23

6 Q4. Ultrasound and X-rays are waves used in hospitals to create images of the inside of the human body. To produce the images below, the waves must enter the human body. Ultrasound scan of an unborn child X-ray of a broken bone Isabelle Limbach/Thinkstock itsmejust/istock (a) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate. Describe the features of ultrasound and X-rays, and what happens to each type of wave after it has entered the human body. (6) Page 6 of 23

7 (b) It would not be safe to use X-rays to produce an image of an unborn child. Explain why. (c) Ultrasound can be used for medical treatments as well as for imaging. Give one use of ultrasound for medical treatment. () (Total 9 marks) Q5. (a) The diagram shows a microphone being used to detect the output from a loudspeaker. The oscilloscope trace shows the wave pattern produced by the loudspeaker. (i) How many waves are produced by the loudspeaker in seconds?... () How many waves are produced by the loudspeaker every second? Assume the input to the loudspeaker does not change. () Page 7 of 23

8 (iii) A person with normal hearing cannot hear the sound produced by the loudspeaker. Explain why. (b) The diagram shows how a very high frequency sound wave can be used to check for internal cracks in a large steel bolt. The oscilloscope trace shows that the bolt does have an internal crack. (i) Explain what happens to produce pulse A and pulse B. Page 8 of 23

9 Use the information in the diagram and the equation in the box to calculate the distance from the head of the bolt to the internal crack. distance = speed time Speed of sound through steel = 6000 m/s Show clearly how you work out your answer. (3) (Total 9 marks) Q6. (a) The diagrams show oscilloscope traces for the same musical note played on two different instruments. The oscilloscope settings are not changed. (i) How can you tell, from the diagrams, that it is the same musical note? () How can you tell, from the diagrams, that the musical note has been played on different instruments? () Page 9 of 23

10 (b) This passage is from an electronics magazine. Electronic systems can be used to produce ultrasound waves. These waves have a higher frequency than the upper limit for hearing in humans. Ultrasound waves are partially reflected when they meet a boundary between two different media. (i) Approximately what is the highest frequency that humans can hear? State the number and the unit.... () What does the word media mean when it is used in this passage? () (iii) What happens to the ultrasound which reaches the boundary between two different media and is not reflected? (Total 6 marks) Q7. (a) Human ears can detect a range of sound frequencies. (i) Use the correct answers from the box to complete the sentence The range of human hearing is from about... Hz to... Hz. What is ultrasound? () Page 0 of 23

11 (iii) Ultrasound can be used to find the speed of blood flow in an artery. State one other medical use of ultrasound. () (b) The speed of an ultrasound wave in soft tissue in the human body is m / s and the frequency of the wave is Hz. Calculate the wavelength of the ultrasound wave. Use the correct equation from Section B of the Physics Equations Sheet... Wavelength =... m (c) When ultrasound is used to find the speed of blood flow in an artery: an ultrasound transducer is placed on a person s arm ultrasound is emitted by the transducer the ultrasound is reflected from blood cells moving away from the transducer the reflected ultrasound is detected at the transducer. Describe the differences between the ultrasound waves emitted by the transducer and the reflected waves detected at the transducer..... (Total 8 marks) Q8. Different parts of the electromagnetic spectrum have different uses. (a) The diagram shows the electromagnetic spectrum. Radio waves Microwaves Infrared Visible light Ultraviolet X-rays Gamma rays Page of 23

12 (i) Use the correct answers from the box to complete the sentence. amplitude frequency speed wavelength The arrow in the diagram is in the direction of increasing... and decreasing.... Draw a ring around the correct answer to complete the sentence. The range of wavelengths for waves in the electromagnetic 0-5 to 0 4 spectrum is approximately 0-4 to to 0 5 metres. () (b) The wavelength of a radio wave is 500 m. The speed of radio waves is m / s. Calculate the frequency of the radio wave. Use the correct equation from Section B of the Physics Equations Sheet. Give the unit Frequency =... (3) (c) (i) State one hazard of exposure to infrared radiation. () State one hazard of exposure to ultraviolet radiation. () (d) X-rays are used in hospitals for computed tomography (CT) scans. (i) State one other medical use for X-rays. () Page 2 of 23

13 State a property of X-rays that makes them suitable for your answer in part (d)(i). () (iii) The scientific unit of measurement used to measure the dose received from radiations, such as X-rays or background radiation, is the millisievert (msv). The table shows the X-ray dose resulting from CT scans of various parts of the body. The table also shows the time it would take to get the same dose from background radiation. Part of the body X-ray dose in msv Time it would take to get the same dose from background radiation Abdomen years Sinuses months Spine months A student suggests that the X-ray dose and the time it would take to get the same dose from background radiation are directly proportional. Use calculations to test this suggestion and state your conclusion. (3) (Total 3 marks) Page 3 of 23

14 M. Quality of written communication award for a sensible sequence of two points X-rays do not go through lead accept lead protects them from the X-rays accept not exposed to X-rays lead stops / reduces risk of X-rays harming / damaging / killing (persons) cells accept X-rays (may) cause cancer accept organs for cell do not accept references to electric shock do not accept stops bones of people showing on X-ray answers involving the horse wearing an apron are incorrect references to gamma rays are incorrect [3] M2. (a) (i) J and L both required, either order K (iii) L highest frequency reason does not score if L not chosen accept most waves (on screen) do not accept frequency above (Hz) do not accept cannot hear it (b) transmitter detector computer all three in correct order allow mark for one correct 2 [6] Page 4 of 23

15 M3. (a) X-rays are ionising or X-rays kill / damage cells accept cause cancer any stray X-rays are absorbed by screen which reduces the radiation dose to the radiographer (b) (c) medical records / X-ray records of people with cancer a CT scan gives a 3D image therefore the image can be observed from different directions [7] M4. (a) Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response. Examiners should also refer to the information in the Marking guidance, and apply a bestfit approach to the marking. 0 marks No relevant / correct content. Level (-2 marks) There is a basic description of either wave OR What happens to either wave when they enter the body. However there is little other detail. Level 2 (3-4 marks) There is either: A clear description of BOTH waves OR A clear description as to what happens to BOTH waves inside the body OR A clear description of ONE of the waves with clear detail as to what happens to either wave inside the body. Level 3 (5-6 marks) There is a detailed description of BOTH of the waves AND A detailed description as to what happens to EITHER wave inside the body. Page 5 of 23

16 Examples of the points made in the response: Description of an X-ray X-rays are electromagnetic waves / part of the electromagnetic spectrum do not allow a description of a property eg X-rays travel X-rays are (very) high frequency (waves) through a vacuum / at the speed of light X-rays are (very) high energy (waves) X-rays have a (very) short wavelength Wavelength (of X-rays) is of a similar size to (the diameter of) an atom X-rays are a transverse wave correct description acceptable oscillations / vibrations are perpendicular (at 90 ) to direction of energy transfer X-rays are ionising radiation Description of ultrasound ultrasound has a frequency above (hertz) or ultra sound is above hertz ultrasound is above / beyond the human (upper) limit (of hearing) accept ultrasound cannot be heard by humans ultrasound is a longitudinal wave correct description acceptable oscillations / vibrations (of particles) are parallel (in same direction) to direction of energy transfer Statement(s) as to what happens to X-rays inside the human body: X-rays are absorbed by bone X-rays travel through / are transmitted by tissue / skin Statement as to what happens to ultrasound inside body: ultrasound is (partially) reflected at / when it meets a boundary between two different media (b) travel at different speeds through different media (because the X-rays) are ionising accept a description of what ionising is 6 Page 6 of 23

17 (they will) damage cells instead of cell, any of these words can be used: DNA / genes / chromosomes / nucleus or mutate cells / cause mutations / increase chances of mutations or turn cells cancerous / produce abnormal growths / produce rapidly growing cells do not accept they can be dangerous (to human health) do not accept damage to soft tissue or kill cells (c) any one from: removal / destruction of kidney / gall stones repair of damaged tissue / muscle accept examples of repair, eg alleviating bruising, repair scar damage, ligament / tendon damage, joint inflammation accept physiotherapy accept curing prostate cancer or killing prostate cancer cells removing plaque from teeth cleaning teeth is insufficient [9] M5. (a) (i) 3 (iii) or their (a)(i) correctly calculated any two from: frequency is above (Hz) accept the frequency is frequency is above the upper limit of audible range upper limit of audible range equals (Hz) ignore reference to lower limit it is ultrasound/ultrasonic 2 (b) (i) wave (partially) reflected Page 7 of 23

18 at crack to produce A and end of bolt to produce B accept at both ends of the crack (m) allow 2 marks for time = allow mark for time = answers 0.5 or 0.05 or 0.09 gain 2 marks answers 0.8 or 0.03 gain mark the unit is not required but if given must be consistent with numerical answer for the available marks 3 [9] M6. (a) (i) same frequency / period / pitch / wavelength ignore references to amplitude differences in waveform / shape / quality accept the diagrams are not identical (b) (i) Hz / hertz or 20 khz / kilohertz in both cases, if the symbol rather than the name is used, it must be correct in every detail material(s) / substance(s) (through which sound travels) (iii) is absorbed accept (some) sound (energy) is transformed / transferred as heat / thermal energy is transmitted accept is refracted accept changes speed accept changes velocity do not accept is diffracted do not accept is diffused do not accept is dissipated [6] M7. (a) (i) 20 Page 8 of 23

19 either order accept ringed answers in box (frequency) above human range accept pitch for frequency or (frequency) above (Hz) do not accept outside human range allow ecf from incorrect value in (a)(i) (iii) any one from: pre-natal scanning accept any other appropriate scanning use do not accept pregnancy testing removal / destruction of kidney / gall stones repair of damaged tissue / muscle accept examples of repair, eg alleviating bruising, repair scar damage, ligament / tendon damage, joint inflammation accept physiotherapy accept curing prostate cancer or killing prostate cancer cells removing plaque from teeth cleaning teeth is insufficient (b) (c) (m) = λ gains mark for reflected waves must be clear whether referring to emitted or detected / reflected waves if not specified assume it refers to reflected wave any two from: 2 frequency decreased wavelength increased intensity has decreased allow amplitude / energy has decreased allow the beam is weaker 2 [8] M8. (a) (i) frequency wavelength Page 9 of 23

20 0-5 to 0 4 (b) correct substitution of / 500 gains mark 2 Hz (c) (i) (skin) burns skin cancer / blindness (d) (i) any one from: (detecting) bone fractures (detecting) dental problems treating cancer any one from: affect photographic film absorbed by bone transmitted by soft tissue kill (cancer) cells answer must link to answer given in (d)(i) (iii) 9 / 36 = / 2 = / 6 = 0.25 accept: 36 / 9 = 4 2 / 0.5 = 4 6 / 4 = 4 2 conclusion based on calculation two calculations correct with a valid conclusion scores 2 marks one correct calculation of k scores mark [3] Page 20 of 23

21 E. Providing of a copy of the Electromagnetic Spectrum enabled many candidates to correctly identify the types of waves utilised in various applications, but few candidates chose radio as the answer to part (a)(i). In part (b) few candidates realised the commonality of the speed of these waves. E2. (a) (i) Just over 72% of candidates recognised which two traces had the same amplitude. (iii) Nearly 83% of candidates knew which trace represented the loudest sound. A large number of candidates incorrectly indentified the ultrasound as trace M with the reason because it can t be heard. Of the 53% of candidates who correctly identified trace L many went on to describe characteristics of ultrasound rather than relating their answer to the traces shown in the question and therefore failed to gain the second mark. (b) This question was well answered with 69% of candidates gaining both marks. Only 8.5% of candidates failed to score at least one mark. E4. (a) Very few candidates obtained level 3 (5 or 6 marks), about half obtained level ( or 2 marks). In general, the responses regarding X-rays were answered in more detail than ultrasound. Many candidates were able to describe what the wave did, but failed to give accurate or detailed descriptions of the waves. Wavelength and frequency descriptions were often muddled. In many wrong responses, candidates failed to answer the question posed, often just appearing to write down any facts they had learned. (b) (c) Almost half of the candidates failed to gain any mark on this question. Often wrong responses detailed how X-rays affected the human body, organs or tissues; rather than damage at a cellular level. Less than one third of candidates could give a medical treatment using ultrasound. The most common correct response related to the treatment or removal of kidney stones. Many candidates with incorrect responses failed to note that the question asked for other than imaging and stated scans of a fetus as their answer. Page 2 of 23

22 E5. (a) (i) A disappointing response to this part question with only just over 64% of candidates being able to count the number of waves shown correctly. With the benefit of error carried forward just over 80% of candidates were able to score this mark. (iii) This was generally well answered with only a small proportion of candidates (9%) failing to score any marks. Most candidates knew the range of human hearing. (b) (i) many candidates failed to score marks because correct terminology was not used: instead of reflection, words used included detected, repulsed, bounced back, echoed and transmitted. There was some confusion between reflection and refraction. Misconceptions included that both pulses A and B resulted from cracks and that from A to B was the extent of the crack. Very few candidates (4%) scored all three marks. However many candidates scored some marks by showing a correct method using an incorrect distance. Others gained a mark for showing a method but forgetting to include the reflected distance. There was some confusion over the appropriate unit to give the numerical answer. E6. (a) (i) The majority of candidates scored a mark. Most candidates were able to explain that the diagrams represent different musical instruments because there are differences in detail between their shapes. (b) (i) Most candidates knew the numerical value of the required frequency but some of them lost the mark because of careless use of units as illustrated by khz. (iii) In part (b) most candidates understood the meaning of the word media in the context of the short passage on ultrasound. Most candidates were able to obtain one mark out of the two for stating that some of the ultrasound is absorbed. E7. (a) (i) Three-quarters of the students knew the frequency range of human hearing. (iii) Three-quarters of students knew what ultrasound is. Nearly all students could state a medical use of ultrasound. Most referred to viewing a fetus but other statements such as pregnancy testing and looking at babies did not score the mark. (b) (c) The calculation which involved rearranging the wave equation and using data given in standard form was very well answered by the vast majority of students. Ultrasound waves were emitted and the reflected waves from an object, moving away, were detected. Less than one-fifth of the students could correctly describe the differences between the emitted and reflected waves because it was often not clear which wave was being referred to in the answers. Page 22 of 23

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