This is a deck containing multiple choice questions for Physics for the FRCR with answers and brief explanations
| Front | True or false. As per IRMER 2000It is bonding on the employer to identify the referrer.Only doctors and dentists may act as referrersRadiographers can perform the role of practitionersThe employer is responsible for ensuring patient doses are are low as reasonably applicableA referrer is not liable for prosecution |
| Back | TrueFalse - Nurse practitioners and Physiotherapists may also refer. But they must be state registered.TrueTrueFalse - They can be prosecuted if adequate clinical information or pregnancy status of the patient is not provided |
| Front | 7. Image quality and noise in image intensifiers:a. Noise in fluoroscopy is predominantly electrical noise caused by minification gainb. SNR can be increased by increasing the kV across the intensifierc. SNR can be increased by frame averagingd. Typical resolution on the monitor of a fluoroscopy system is 1.2–3 lp/mm depending on magnificatione. Veiling glare and geometrical distortion are common artefacts in fluoroscopy |
| Back | 7a. False As with other X-ray radiography, the requirement to keep doses ALARP means that the number of absorbed X-ray photons is the quantum sink, and that quantum mottle is the predominant cause of noise in the image.7b. FalseIncreasing kV across the intensifier would increase flux gain, but this would increase noise in the same proportion and therefore the SNR would not change. 7c. TrueFrame averaging adds the signal from successive frames taken over a period of time. This increases the SNR and provides a higher quality image as long as the patient does not move during this time. 7d. TrueThe resolutions of the television and display systems are the limiting factors. 7e. TrueVeiling glare is caused by light scattering within the output phosphor and results in loss of contrast in darker areas. It also results in the centre of the image being brighter than the periphery. Geometrical distortion is caused by focusing inaccuracies and by the curved input screen that tends to magnify the periphery of the image. This is not normally noticeable when imaging the complex organs of the body, but images of straight objects such as wires in interventional work may be noticeably bent by this effect. |
| Front | 23. PET scanner design:a. A ring of approximately 1000 NaI detectors surrounds the patientb. Each detector has only one ‘line of response’; that is with the detector directly oppositec. Photons detected within 10-9 sec of each other are considered simultaneousd. Time of flight PET improves image contraste. 3D acquisition improves sensitivity |
| Back | 23a. False Bismuth germinate is used as it has a higher intrinsic efficiency for the higher energy photons used in PET; compare this to NaI used in lower energy SPECT. Current scanners have up to 30 000 detectors.23b. FalseEach detector will have a ‘line of response’ with many opposing detectors. The area of the scan plane covered by these describes a fan shape. In addition, recent scanners allow lines of response to detectors in adjacent rings in the z-direction.23c. TrueThis is determined somewhat by the speed of the scanner electronics.23d. TrueModern scanners are able to very precisely measure the time of photon detection. Time of flight PET uses minor time differences in detection to provide further position information; along a given line of response, the two gamma photons from positron annihilation will only truly arrive simultaneously if they arose at exactly the midpoint of the line. If the event occurred closer to one detector, that detector will receive the photon marginally sooner. Knowing the distance between detectors and the speed of photons allows that distance to be calculated. With better positioning, there is less blur in the reconstructed image. 23e. True3D acquisition refers to the inclusion of coincident data between adjacent detector rings as well as those occurring in the plane of a single ring of detectors. For a given dose administered to the patient more events will be detected compared to 2D acquisition |