Tag the correct answer for each of the multiple-choice questions. Only one answer is correct. For the open questions , the complete calculations must be attached.
Questions 1 till 33 are for everybodt.
Questions 34 till 42 are only for RPO MR.
Questions 43 till 51are only for RPO VRS-D.
The examination is based on the syllabus Radiation Protection Officer - MR and VRS-D, written by dr. F. Pleiter and dr. H.F. Boersma. You will find the correct answers here .
Complete the sentence: The number of electrons in an electrically neutral atom is equal to the...
- atomic number
- mass number
- difference between mass number and atomic number
- neutron number
Complete the sentence: The two nuclides 18 9F and 19 9F...
- are isotopes
- are isomers
- have the same mass number
- none of the answers [a], [b] and [c] is correct
- A radioactive source contains an activity of 1 MBq. After a period of 20 weeks, the remaining activity turns out to be 1 kBq. What is the half-life?
- about 1 week
- about 10 days
- about 2 weeks
- about 20 weeks
The results of an activity measurement are plotted in Figure A . It shows the count rate (vertical scale) as a function of the elapsed time in seconds (horizontal scale). Answer the next question.
- What is the half-life of this radionuclide?
- about 15 seconds
- about 25 seconds
- about 55 seconds
- about 100 seconds
- The above figure shows the decay scheme of 115mIn. Which of the following statements is correct?
- 115mIn is a pure ß-emitter
- 115In is a pure ß-emitter
- there is no isomeric state of 115In
- 115Sn is radioactive
- What happens during the photo-electric effect?
- the energy of a ß-particle is transferred to an electron
- a photon is absorbed by an electron
- the energy of a photon is partially transferred to an electron
- an incoming photon is scattered
Complete the sentence: The probability of the photo-electric effect to occur...
- increases if the atomic number of the material becomes larger
- hardly depends on the atomic number of the material
- increases if the photon energy becomes larger
- hardly depends on the photon energy
- Which is the range in air of α-particles with an energy of about 5 MeV ?
- a few micrometers
- a few millimeters
- a few centimeters
- a few meters
- Which is the maximum range in air of 1 MeV ß-particles?
- about 0.4 cm
- about 4 cm
- about 40 cm
- about 400 cm
- What is accounted for by the build-up factor B ?
- the contribution of forward-scattered radiation to the dose
- the effect of repeated radiation doses
- the accumulation of internal contamination due to several intoxications
- the accumulation of several radioactive surface contaminations
The nuclide 32P is a pure ß--emitter with a maximum energy of 1.71 MeV. A 32P source is sealed inside plexiglass with a thickness of 1 mm. The specific mass of plexiglass is 1.2 g/cm3.
- Which 32P-produced radiation is transmitted by this enclosure?
- no radiation
- only ß-radiation
- only annihilation radiation
- both ß-radiation and annihilation radiation
- Which is the least effective material for shielding neutrons?
- In a radiation field, an energy of 2 joules is absorbed in an organ with a mass of 100 grams. How big is the absorbed dose?
- 50 Gy
- 20 Gy
- 0.05 Gy
- 0.02 Gy
- For which calculation is the tissue weighting factor wT used?
- the conversion of absorbed dose to equivalent dose
- the conversion of equivalent dose to effective dose
- both of the conversions named at [a] and [b]
- none of the conversions named at [a] and [b]
A worker at a particle accelerator has been exposed to an absorbed γ-dose of 1.0 mGy and an absorbed neutron dose of 0.5 mGy. The radiation weighting factor of the involved neutrons is wR = 8.
- What is the received equivalent dose?
- 1 mSv
- 1.5 mSv
- 4 mSv
- 5 mSv
Complete the sentence: A large value of e(50) implies...
- a large radiotoxicity
- a small radiotoxicity
- that the activity is slowly removed from the body by excretion
- that the activity is quickly removed from the body by excretion
- The contribution of natural radiation to the annual effective dose in the Netherlands is mainly caused by a single source. Which is this radiation source?
- cosmic radiation
- For which application can a Geiger-Müller counter be used?
- to measure the energy of α-particles
- to measure the energy of ß-particles
- to measure the energy of γ-fotons
- for none of the applications named at [a], [b] and [c]
Each interaction of a γ-ray photon with the detector material produces an electronic signal at the output of a NaI detector.
Complete the sentence: At a fixed setting of the electronic equipment, the pulse height of this output signal is proportional to the...
- intensity of the radiation
- energy transferred to NaI
- number of incoming photons
- inverse of the square of the distance between source and detector
- Which of the following detectors can in principle be used as a dose-rate monitor? Give the best and/or most complete answer.
- proportional counter
- Geiger-Müller counter
- NaI detector
- any of the detectors named at [a], [b] and [c]
- Which is the best detector to measure the dose rate caused by a ß-source with a maximum ß-energy of 1 MeV ?
- end-window Geiger-Müller counter that displays the counting rate in counts per second
- windowless Geiger-Müller counter with a wall with a mass thickness of 1 g/cm2, that is calibrated in mSv/h
- proportional counter with a window with a mass thickness of 7 mg/cm2, that displays µSv/h
- windowless proportional counter with a wall with a mass thickness of 1 g/cm2, that is calibrated in mSv/h
The electronic output signals of a detector can be sorted according to pulse height in a so-called multi-channel analyser, which makes it possible to display the energy distribution (= spectrum) of the radiation on a monitor.
- For which type of measurement is a multi-channel analyser NEVER used?
- activity measurement
- dose rate measurement
- contamination measurement
- γ-ray spectrometry
- Which type of tissue is most sensitive to ionizing radiation?
- tissue that receives the largest dose
- tissue with cells that divide quickly
- tissue that is located in the abdominal region
- tissue with cells that no longer divide
- Which of the following diseases can be regarded as a stochastic effect due to ionizing radiation?
- reduction in the number of white blood corpuscles
- temporary sterility
- permanent sterility
- An unborn child receives an absorbed dose of 0.5 Gy during the first ten days after the conception. What is the possible consequence of this irradiation?
- prenatal death
- death shortly after birth
- a nonlethal effect such as a deformed organ or mental retardation
- a tumor after birth
- Which is the risk coefficient for fatal stochastic effects due to ionizing radiation?
- about 0.01 per sievert
- about 0.02 per sievert
- about 0.05 per sievert
- about 0.10 per sievert
- What does the ALARA principle mean?
- the application must be justified, which means that the benefits outweigh the disadvantages
- preference for any alternative method in which no ionizing radiation is applied
- no dose shall exceed the dose limits
- the received dose must be kept as low as reasonably achievable
- According to the Decree on Basic Safety Standards Radiation Protection, which is the annual limit for the effective dose of an exposed A-worker?
- 100 μSv
- 2 mSv
- 20 mSv
- 50 mSv
Complete the sentence: According to the Decree on Basic Safety Standards Radiation Protection, an area is classified as supervised area if in this area it is possible to receive an annual effective dose of...
- more than 1 mSv, but less than 6 mSv
- more than 6 mSv, but less than 10 mSv
- more than 10 mSv, but less than 20 mSv
- more than 20 mSv
- Does a risk inventory and evaluation (RI&E) always has to be carried out by the radiation protection officer?
- no, this may only be done by a radiation protection expert
- no, this may only be done by a registered radiation protection expert
- no, this may in principle be done by everyone
According to the Decree on Basic Safety Standards Radiation Protection, a radioactive substance is exempt from government control if either the activity or the activity concentration is lower than the exemption values for moderate quantities (up to 1000 kg).
nuclide activity (Bq) activity concentration (Bq/g) 3H 109 106 14C 107 104 131I 106 102 226Ra 104 1 241Am 104 1
- Consider the exemption values in the above table. Which of the following radioactive substances, each less than 1000 kg, is NOT exempt?
- 6×108 Bq 3H with an activity concentration of 6×107 Bq/g
- 3.7×106 Bq 131I with an activity concentration of 3×102 Bq/g
- 3.7×103 Bq 226Ra with an activity concentration of 3.7×1010 Bq/g
- 3×103 Bq 241Am with an activity concentration of 3×109 Bq/g
The ISO-classification code of a sealed source consists of the letter C followed by five digits, each referring to a specific test on the items temperature and thermic shock, pressure, mechanical shock, vibration, and puncture. The value of the digit represents the strength of the test to which the source was subjected.
Complete the sentence: A sealed 63Ni source with ISO-classification code 32211, used in a gas chromatograph, has been tested on...
- all items
- all items, with the most severe test for temperature
- all items, with the most severe test for vibration and puncture
- NOT all items
- Which of the following precautions must ensure that sealed sources do not get lost? Give the best and/or most complete answer.
- a suitable record of the use of all sources
- raising awareness among workers about the risk of theft
- storage of the source in a vault when it is not in use
- all precautions named at [a], [b] and [c]
Questions 34 till 42 are only for RPO MR.
- Why is protection against X-radiation usually relatively simple?
- because X-radiation usually can be shielded with a thin layer of lead
- because the radiation weighting factor wR for X-radiation is very small
- because the dose rate of an X-ray machine is always very small
- because the penetration depth of X-radiation into the body is very small
The half-value thickness is the amount of material needed to reduce the dose rate by a factor of two.
- Which of the following properties holds for the radiation that is generated by an X-ray device?
- the half-value thickness increases when the exposure time increases
- the half-value thickness decreases when the exposure time increases
- the half-value thickness of the primary beam is larger than the half-value thickness of the scattered beam
- the half-value thickness of the primary beam is smaller than the half-value thickness of the scattered beam
The difference in density of light and dark parts of an X-ray image is called contrast. If the contrast is extremely large, only the shades white and black show up. If the contrast is extremely small, the image shows only a single shade of grey.
- In which way can one reduce the contrast of the dental photo?
- by decreasing the voltage across the X-ray tube
- by increasing the voltage across the X-ray tube
- by decreasing the current through the X-ray tube
- by increasing the current through the X-ray tube
Complete the sentence: A cone-beam CT-scanner in the dental practice...
- may be used without any restrictions
- may be used without a radiation protection officer
- must be registered with the ANVS
- is subject to a license
The voltage acreoss the X-ray tube is set to 50 kV. The maintenance engineer replaces the existing filter of 1 mm aluminum with a 2 mm aluminum filter. The entrance dose with the old filter was 1 mSv. To answer the next question, you may use the data in Figure B .
- How big is the entrance dose with the new filter?
- 0.7 mSv
- 0.9 mSv
- 1.1 mSv
- 1.4 mSv
Point source A emits only γ-photons with an energy of 500 keV and point source B emits only ß-particles with an average energy of 500 keV. Both sources contain the same amount of activity and absorption of radiation is negligible.
- Which of the following statements is correct?
- A gives rise to a much lower dose rate than B
- A and B give rise to approximately equal dose rates
- A gives rise to a slightly higher dose rate than B
- A gives rise to a much higher dose rate than B
An old smoke detector containing 33 kBq 241Am is disposed of by dropping it into the waste bin. A little child finds the smoke detector, takes it apart, and ingests an estimated 10% of the original activity. The dose conversion coefficient for ingestion of 241Am is 2.0×10-7 Sv/Bq.
- Which is the committed effective dose for the child due to this contamination?
- about 0.007 mSv
- about 0.07 mSv
- about 0.7 mSv
- about 7 mSv
To answer questions 41 and 42, the full calculation must be given. You may use the data given in Figure B.
tube voltage 90 kV tube current 6 mA filter 3 mm aluminum exposure time 0.3 seconds distance focus - skin 50 cm
- Calculate the equivalent skin dose using the above data. (maximal 4 points)
activity 100 GBq source constant 0.12 μSv m2 MBq-1 h-1 length pair of tongues 50 cm exposure time 10 s the RPO is classified as exposed A-worker
- Answer the next questions. (maximal 6 points)
- calculate the effective dose received by the RPO
- calculate the time that the job should have lasted until the annual limit for the effective dose of this worker is reached
Questions 43 till 51 are only for RPO VRS-D.
There is an activity limit for removable surface contamination.
- Which is the limit in case of α-activity?
- 0.4 Bq/cm2
- 4 Bq/cm2
- 0.4 Bq/m2
- 4 Bq/m2
Complete the sentence: Used scintillation liquid containing carcinogenic xylene...
- must always be disposed of as radioactive waste
- may always be disposed of as chemical waste
- may always be discharged to the sewage system
- none of the answers [a], [b] and [c] is correct
- Which property is crucial for the fume hood to function correctly?
- the air circulation inside the hood is not obstructed
- the hood can easily be decontaminated
- the window of the hood can be completely closed
- the window of the hood can be completely opened
- Which of the following precautions is most effective in avoiding dispersion of a radioactive contamination while applying open radioactivity in a radionuclide laboratory?
- wearing a protective coat
- wearing safety glasses
- using a splash tray
- correct sorting of radioactive waste
The doctor injects 500 MBq 99mTc. The average distance between activity and fingers is 1 cm. The doctor holds the syringe during 10 seconds. The source constant of 99mTc is h = 0.02 µSv m2 h-1 MBq-1.
- Which is the equivalent dose on the fingers?
- about 30 µSv
- about 100 µSv
- about 300 µSv
- about 1000 µSv
The gooseneck of a sink in the radionuclide laboratory is found to be contaminated with 131I. The equivalent dose rate at a distance of 30 cm from the contamination is 0.3 µSv/h. The source constant of 131I is h = 0.066 µSv m2 h-1 MBq-1. Shielding by the gooseneck may be neglected.
- Which is the activity of the contamination?
- about 0.07 MBq
- about 0.2 MBq
- about 0.4 MBq
- about 1.4 MBq
A measurement, carried out one day after an accident, shows that a worker has inhaled an activity of 360 Bq 131I. The dose conversion coefficient for inhalation of 131I is 1.1×10-8 Sv/Bq.
- Which is the committed effective dose for the worker due to this accident?
- about 0.4 µSv
- about 4 µSv
- about 40 µSv
- about 400 µSv
For questions 50 and 51, the full calculation must be given. You may use the data given in Figure C.
activity injection fluid 600 MBq volume injection fluid 2 ml volume droplet 0.05 ml e(50)injection 1.1x10-11 Sv/Bq e(50)inhalation 2.9x10-11 Sv/Bq the nurse is not an exposed worker
- Answer the next questions. (maximal 4 points)
- calculate the activity of the droplet
- calculate the committed effective dose due to this accident
- check whether the annual limit for the nurse is exceeded - justify your answer
laboratory class D workplace table e(50)ingesttion 1.4x10-10 Sv/Bq e(50)inhalation 8.0x10-10 Sv/Bq working time per labeling half a day = 4 hours per week activity per labeling 100 kBq
- Answer the following questions. (maximal 6 points)
- calculate the maximum activity Amax that may be handled
- calculate the contribution of this practice to the load factor B
|Last modified:||28 August 2019 7.52 p.m.|