Radiology EXAM on DXA scans

A radiologist or someone who is an expert in radiology and DXA scans should answer these questions

Question 76 of 80 Which of the following is true regarding the diagnosis of osteoporosis?
A A fracture with minimal trauma, in the right clinical setting, is sufficient to diagnose the disease on clinical grounds.
B Standard X-rays are a relatively sensitive method of diagnosing the disease
C Spinal QCT is diagnostic of osteoporosis if the T score at the spine is less than -2.5
D The measurement of bone mineral density by DXA may be falsely decreased in the spine by osteoarthritis
E Scanning one skeletal site using DXA or QCT (Quantitative Computed Tomography) is all that is needed in the majority of patients to confirm or exclude osteoporosis

Question 37 of 80 Which of the following statement is false?
A The precision error in a femoral neck BMD measurement is generally larger than for a spine BMD
B If the Z-score is below -2.0, this may indicate a possible secondary cause of osteoporosis
C The Z-score is the number of standard deviations the patient’s BMD is from the mean BMD for a gender-matched young normal reference population
D The T-score gives us an idea of the fracture risk
E The WHO criteria for osteoporosis based on T-scores does not apply to all skeletal sites

Question 77 of 80 Regarding serial BMD measurements in a postmenopausal woman
A A change in BMD of 6 to 7% per annum is not uncommon
B A change in BMD of 1 to 2 % per annum is not uncommon
C Yearly BMD measurements will usually detect a significant change
D A change in BMD of 6 to 7% per annum is always spurious
E Therapy with bisphosphonates will cause a typical increase in BMD of 10 to 15% over 1 to 2 years
Question 74 of 80 Calcified tissue in the region being measured, eg kidney stone, staples from a previous operation:
A should be marked as ‘Soft tissue’ if the software allows
B should be marked as ‘Bone’ if the software allows
C invalidates the scan
D should be ignored so long as it does not lie over the bone
E will not usually affect BMD if it is not adjacent to the vertebrae being measured

Question 71 of 80 The presence of the navel ring over L4 in a lumbar spine scan would require you to recommend:
A Making no changes
B Repeat the scan with navel ring removed if patient is still present
C If patient has left, exclude L4 from the analysis and include this in the report
D Use the analysis software exclusion tools to remove the navel ring and report normally and report this to the physician
E B and C

Question 70 of 80 Of the following features demonstrated on a lumbar spine scan you have been asked to review, which feature is the least important with respect to a reliable bone density assessment.
A Spine not straight and centred on image
B Spine not centred on image
C The patient has lumbar osteoarthritis
D The patient has 6 lumbar vertebrae
E The patient has a navel ring over L4 (not removable)

Question 67 of 80 Which one of the following is false?
A A Z score less than -2.0 may indicate an underlying condition resulting in an accelerated rate of bone loss (secondary osteoporosis)
B All patients who are osteoporotic on DXA (T score <-2.5) should be fully investigated to exclude all causes of secondary osteoporosis.
C Osteoporosis is defined as a DXA T score < -2.5 in the axial skeleton lumbar spine or hip
D Some patients may have good BMD in the proximal femur while at the same time having osteoporosis in the lumbar spine
E In children T scores are of no value since BMD has not yet peaked

Question 59 of 80 With Dual hip DXA scans
A The mean of the T scores for the two hips should be used for diagnosis
B Precision of mean hip BMD is the same as for a single hip measurement
C The mean of the BMD of the two hips should in most cases be used for monitoring
D Wards triangle is the best site due to its high trabecular content
E BMD in both hips is always very similar due to equal weight bearing

Question 79 of 80 A patient has a vertebral fracture today at L3. The BMD (L2-L4) tomorrow when compared to the BMD yesterday will be:
A Increased due to compaction of the bone into a smaller area
B Decreased due to compaction of the bone into a smaller area
C Unchanged
D Depends on whether the patient has commenced treatment
E Depends on the DXA scanner used
Question 80 of 80 A simple moving average plot for your DXA scanner BMD phantom has recently recorded the following values in standard deviations from the mean: 0.2, 0.5, -0.1, 0.1, -0.3, -0.8, -0.6, -1.2, -0.7, -1.4, -0.9, -1.6, -1.1, -1.0, -1.7. What does this suggest about the control status of the scanner?
A There is nothing wrong. It’s just a statistical aberration
B There is insufficient data to decide, perform 5 phantom scans and check their values
C The scanner is very likely to be out of control, and needs to be checked by service as soon as possible
D You will only call service if the moving average plot exceeds +/- 2 SD from the mean
E You will only call service if the moving average plot exceeds +/- 2 SD from the mean and other rules are broken as well
Question 68 of 80 Which of the following is true?
A All DXA machines always provide equivalent BMD results in g/cm2
B DXA machines always provide equivalent BMD results in T score
C DXA machines always provide equivalent BMD results in Z score
D DXA machines provide similar BMD results in sBMD (standardized BMD)
E The WHO criteria for osteoporosis can be applied to any skeletal site
Question 65 of 80 Hip Structural/Strength Analysis or Advanced Hip Assessment
A Assesses mechanical properties of key ‘fracture’ sites such as the Femoral Neck
B Attempts to improve the prediction of hip fracture risk
C Requires special attention to patient positioning and scan quality
D Is currently used for research of ‘at-risk’ populations rather than for individuals
E All of the above

Question 64 of 80 Which of the following is not true in relation to vertebral assessment by DXA (i.e. LVA, IVA, MXA):
A It is useful for screening for vertebral fractures
B It is sensitive for identifying moderate to severe vertebral deformities
C there is much lower radiation exposure than a lateral radiograph
D It is better at assessing lumbar rather than thoracic vertebrae
E any vertebral deformity exceeding 20% indicates a vertebral fracture
Question 62 of 80 Bone mineral density (BMD gm/cm2)
A Is a density and so is not affected by bone size
B may be spuriously low in someone of small stature
C Is calculated from measured BMC and Bone Area
D Is sometimes referred to as ‘volumetric BMD’
E All of the above
Question 61 of 80 Lateral spine BMD is :
A useful for osteoporosis diagnosis because it is less effected by arthritis
B often affected by iliac crest obscuring L4 or ribs overlying vertebrae
C unreliable due to variable soft tissue anterior and posterior to the vertebrae
D the best modality for monitoring due to the high trabecular bone content
E B and C
Question 52 of 80 When performing research-based bone densitometry studies
A A ‘research patient’ is where the results are knowingly being acquired for any (possibly additional) reason other than for direct patient care
B If the investigator thinks the dose is below 5 microSv, subjects (including children) are not required to give informed written consent
C If the investigator thinks the dose is below 5 microSv, subjects (except children) are not required to give informed written consent
D In research bone densitometry studies on children, formal requirements are particularly stringent (and justification particularly relevant) because they are below the age of informed consent
E A and D

Question 50 of 80 In relation to Bone Densitometry technologists which of the following is not true:
A They can if they wish, destroy patient scanning records after the results and reports have been sent to the referring doctor
B They must be licensed to operate the DXA equipment
C They must have attended a State-approved course on radiation safety
D They should ensure that regular quality control tests are conducted according to manufacturer’s specifications, and that accurate and permanent records are kept
E None of the above
Question 49 of 80 In a typical adult population, a single effective dose of 1milliSv (1000microSv) above background (7 microsiverts per day) corresponds to a total excess lifetime risk of severe radiation-induced effects, of about:
A 7 cases in 10
B 7 cases in 100
C 7 cases in 10,000
D 7 cases in 100,000
E So low that no attempt is ever made to calculate it
Question 47
A DXA operator determines that his DXA spine scan precision, estimated from duplicate patient measurements (after ethics approval), is 1.5%. Which of the following is true:
A He should review his scanning methods as this in unacceptably high
B This precision estimate can be applied to other technologists using his scanner
C The least significant change for a DXA spine scan in his hands is 1.5%
D The value of 1.5% is a best case scenario and precision in some patients may be worse
E This precision estimate can be applied to other skeletal sites measured by the same technologist
Question 45 of 80 On your system, a plot of phantom BMD Vs Time has been stable over a 2 year period. On yesterday’s phantom scan you noted a +2.3 standard deviation change from baseline. Today’s scan of the phantom is +2.4 standard deviations from the baseline. It is most likely that:
A The scanner is operating normally – continue using the scanner, and monitor it more frequently
B The scanner is operating normally – ignore the result as it is just a statistical anomaly
C The scanner may be out of control – call the service agent to check the scanner
D The scanner may be out of control – scan the phantom at least 5 times and evaluate the results
E The scanner may be out of control – scan the phantom once more and evaluate the result
Question 44 of 80 The simplest tool to monitor if a DXA scanner is operating correctly is measuring phantom BMD, tabulating it and observing if the result is within a tolerance limit (+/- 1.5%). The main limitation of this technique in practise is:
A Regularly scanning the phantom is not practical
B The tolerance limits of +/- 1.5% are too wide
C The tolerance limits of +/- 1.5% are too narrow
D Large changes in scanner performance may be artefactual
E The data are not inspected regularly
Question 38 of 80 Dual photon X-ray Densitometry (DXA):
A Directly measures BMD and bone area
B Directly measures BMC and bone area
C Directly measures BMD, BMC and bone area
D Uses one of its dual energy photons to measure BMD and the other to measure bone area
E A and D

Question 41 of 80 The DXA scanner at your facility has had an X-ray tube failure, and required service. The service engineer has performed the appropriate checks and reported the scanner meets engineering specifications again. You choose to verify that the function is correct with respect to BMD using the quality control phantom and scanning it 10 times. To check the scanner function is the same (within 1%), you should compare the BMD mean and standard deviation of the newly calibrated scanner:
A to nothing – you trust the service engineers report
B to the original phantom scans when the scanner was installed
C to the 10 scans prior to the failure
D to the running mean that was stable prior to failure
E to the entire dataset

Question 36 of 80 A patient returns for a bone density measurement. The previous spine BMD done two years ago at your practice was 1.00 g/cm2. The current measured spine BMD is 0.93 g/cm2. The least significant change (LSC) formula is given below: LSC = 2.8 x s where, s is the precision error. Assuming a precision error of 0.02 g/cm2 for your practice, which of the following is true?
A There is a significant increase in the Spine BMD
B There is a significant decrease in the spine BMD
C There is no significant change in the spine BMD
D This would be a significant increase in BMD if the tests had been performed one year apart
E The level of significance depends on the changes in the hip BMD as well as the spine BMD
Question 35 of 80 Which of the statements below is not true relating to precision of bone densitometry?
A It is a measure of reproducibility
B It can be estimated from repeated measurements on the same person
C It can be minimised by rigorous attention to patient positioning, scan acquisition and analysis
D It is not affected by fluctuations in the operating characteristics of the machine
E It influences the conclusion drawn regarding changes in BMD over time
Question 31 of 80 X-ray lead protective aprons:
A Must be equivalent to at least 9mm lead in terms of radiation stopping power
B Should be folded up carefully when stored
C Reduce the intensity of primary x-rays by approximately 50%
D Stop virtually all scattered x-rays
E All of the above are true

Question 30 of 80 A film badge or TLD:
A Is intended to determine the DXA scanner’s radiation leakage and should be shared by all technolgists using the scanner
B Should be worn outside any shield used concurrently, such as a lead apron
C Is only one means of verifying that facilities for radiation protection are adequate
D May give inaccurate and unhelpful results if it is positioned wrongly on the wearer
E C and D
Question 29 of 80 For radiation protection purposes:
A In clinical practise (excluding research studies) there is no statutory limit to the dose received by patients undergoing an X-ray based diagnosis
B There is no statutory limit to the dose received by attending health workers
C The dose limit for the hands of radiation workers is the same as for other parts of the body
D Personal occupational radiation exposure can be reduced, simply by the wearing of a radiation dosimeter
E Radiation protection laws are ‘draconian’ and primarily devised to prevent the institution from being sued
Question 28 of 80 In relation to radiation dose from bone density measurements:
A The dose from a typical pQCT scan of the forearm is up to 20microSv
B From most DXA scans is so low that ethics approval is not required in research studies
C The radiation dose from fan beam DXA scans is significantly lower (by a factor of ten) than pencil beam scans
D The radiation dose from a whole body DXA scan can be assumed to be zero as long as the gonads are shielded
E The radiation dose from a single PA DXA lumbar spine scan is about one five hundredth of the yearly background dose

Question 25 of 80 In respect of the effects of ionising radiation:
A There is little or no evidence of cancer induction as a result of normal occupational exposures in diagnostic radiology
B There is evidence of radiation injury to patients from high doses of diagnostic x-rays
C Investigation of children using DXA should be avoided unless the results will influence clinical management.
D It is a prudent, though unproven assumption that any level of ionising radiation exposure increases the long term risk of cancers and genetic effects
E All of the above are true
Question 23 of 80 Equivalent and effective doses are distinguished by:
A Equivalent dose relates to a specific tissue or organ but does not account for the relative biological effect of the type of ionising radiation
B Effective dose combines the equivalent doses received by all irradiated tissues or organs, and combines them into a single number using the “tissue weighting factors”
C The numerical value of the effective dose obtained (in Sv) is the lifetime probability of getting cancer
D Since the development of ICRP60, “tissue weighting factors” are no longer used in radiation dose calculations
E The effective dose can be used to calculate the more biologically relevant variable, “the radiation exposure”

Question 16 of 80 Which of the following has not been shown to decrease the risk of osteoporotic vertebral fractures in large clinical trials?
A Raloxifene
B Alendronate
D Risedronate
E Exercise.
Question 14 of 80 A 22 year old woman exercises a lot and is very fit. She has a body mass index of 18kg/m2 and has irregular menstrual periods every 8 to 12 weeks. Which one of the following is true:
A Her bone density is likely to be in the upper range of normal for her age
B A high calcium intake will ensure her bone density is maintained
C She is likely to have reduced bone density and a very high risk of fracture
D Her bone density is likely to be low compared to the age matched mean
E No investigation is needed since she is too young to be at risk of osteoporosis
Question 13 of 80 Two patients have the following characteristics: Patient A: Age 74; Hip BMD 0.60 g/cm2; Previous vertebral fracture. Patient B: Age 75; Hip BMD 0.58 g/cm2; No previous fractures. Which statement is true?
A Patient A has approximately the same risk of future fracture as Patient B
B Patient A is twice as likely to get a further fracture as Patient B
C Patient B is more likely to get a future fracture than Patient A
D Patient A is 4 to 5 times more likely to get a future fracture than Patient B.
E It is too late for Patient A to decrease the risk of further fractures

Question 3 of 80 Bone density increases when anti-resorptive drugs are given because
A The mass and structure of bone is restored
B The mineral density in the tissue increases
C The fat in the marrow decreases
D The cells in the marrow increase
E The anti-resorptive drugs also increase bone formation
Question 2 of 80 Increased bone strength can be achieved by:
A Increasing the thickness of the cortex
B Decreasing the trabecular bone in the marrow
C Increasing the cortical porosity
D Increasing the cross links of the collagen
Question 39 of 80 Bone mass determination in photon absorptiometry devices rely on:
A Integrating the bone edges to the soft tissue baseline
B Accurately determining the bone area by integrating the photon count rate
C Accurately determining the bone edges and calculating the average areal density between bone edges
D Accurately determining the integration of bone edge area
E Limiting the calculation to high photon flux areas

Question 26 of 80 In relation to radiation exposure which of the following is true:
A Most radiation workers receive most of their radiation dose from natural background sources
B Per unit effective dose, occupational radiation exposure is intrinsically more hazardous than natural background exposure
C The general public receive on average most of their radiation dose from medical exposures
D Radiation exposure was not an aspect of life until scientists discovered radium and x-rays
E A macrobiotic diet can guarantee that the body contains negligible radioactive substances, compared with normal living

Question 9 of 80 In relation to progress DXA scans, interpretation should always include:
A Duplicate scans to be performed at each site at each visit
B Comparison of the serial Z scores at each site
C Comparison of the serial BMD in g/cm2 at each site
D Comparison of the serial T scores at each site
E (a) and C
Question 8 of 80 In relation to treatment of osteoporosis:
A The guidelines of the Government’s funding agencies should be the primary guide for therapy decisions
B Treatments should be cost effective and well as reducing the risk of fracture
C In the very elderly it is too late for therapy to be effective
D treatment recommendations may change over time as the costs of therapies change
E B and D

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