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Which weighting factor represents the relative tissue radio-sensitivity? Which weighting factor is a number assigned to different types of ionizing radiations to determine their effect on tissue?
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What is used to account for the differences in tissue sensitivity to ionizing radiation when determining effective dose?
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Radiation Protection
Radiation Protection Review
| Question | Answer |
|---|---|
| Which weighting factor represents the relative tissue radio-sensitivity? Which weighting factor is a number assigned to different types of ionizing radiations to determine their effect on tissue? | Tissue weighting factor (Wt). Radiation weighting factor (Wr) |
| What is used to account for the differences in tissue sensitivity to ionizing radiation when determining effective dose? | Tissue weighting factor (Wt). |
| What are the annual occupation limits for Effective Dose? How many mSv are in each rem? What are the limits in mSv? | 5 rem for the whole body, 50 rem for the skin & extremities, 15 rem for the lens of the eye. 1 rem = 10 mSv. 50 mSv for whole body. 500 mSv for skin/extrmities & 150 mSv for lens of the eye. |
| What is the formula to calculate Equivalent Dose? | EqD = D x Wr. (D) dose, (Wr) Radiation weghting factor. |
| What is the formula to calculate Effective Dose? | EfD = D x Wr x Wt. (D) dose,(Wr) radiation weighting factor, (Wt) tissue weighting factor |
| In regards to the mother receiving x-ray, when is the relative risk the highest for the fetus? | Within the first trimester |
| What is the Cumulative Effective Dose? What is the radiation unit? How would it be determined? | The Collective Effective Dose describes low doses of ionizing radiation exposure of a population or a group. The person-seivert. The # of people x the average effective dose. |
| What are the Regulatory Agencies that enforce radiation protection standards? | NRC, Agreement States, EPA, FDA, OSHA. |
| Which regulatory agency mandates that a Radiation Safety Committee (RSC) be in place? Which agencies recommendations do they use for review? | The NRC. The ICRP. |
| As field area & part thickness increases, what happens to the scatter factor? | The scatter factor increases |
| What are the 4 organizations that set the standards for radiation protection? | ICRP, NCRP, UNSCEAR, NAS/NRC-BEIR |
| What is the gestational dose equivalent limit for the embryo/fetus of a pregnant radiographer? What is the limit per month? | 5 mSv (.5 rem) for the gestational period & not to exceed .5 mSv per month (.005 rem, or 5 mrem). |
| What type of x-ray interaction with matter is responsible for the majority of scatter reaching the IR? | Compton scatter |
| Which type of x-ray interaction does the incident photon eject an outer shell electron while doing so, being deflected with less energy as scatter? | Compton scatter |
| With mA increased, how is ESE affected as the the SSD is increased? Why is the mA increased with the increased SSD? | The ESE increases. As SSD increases, beam intensity decreases resulting in less density on radiograph. |
| When must someone be monitored for radiation exposure? | Anyone who might receive more that 1/10 annual dose limit must be monitored. |
| What is the the threshold range of Acute Radiation Syndrome for the GI system to be affected? How will the illness manifest itself? | The threshold is 600 rad (6 Gy). All of the Acute Radiation Syndrome symptoms along with the epithelial lining of the GI sloughing off |
| What is considered 2ndry radiation? | 2ndry radiation consists of leakage & scatter radiation. |
| What type of dose response relationship skin erythema & hematologic depression, exhibit? | Non linear (Sigmoid Curve) threshold dose response relationship |
| What type of dose response relationship line or curve are leukemia & genetic effects plotted on? | Linear dose response non threshold. |
| Which part of the 1st trimester can skeletal or organ anomalies appear if irradiated? When can mental retardation, or neurological anomalies form? When can spontaneous abortion occur? When can some type of childhood malignant disease occur? | Within the early part of the 2nd to 10th week. In the latter part of the 1st trimester 2nd to 10th week. During the 1st 2 weeks of gestation. If fetal irradiation occurs during the 2nd to 3rd trimester. |
| What's it called when radiation is delivered in portions over a period of time? If a quantity of radiation on biologic material is delivered to a body over a long period of time, how will it compare to the same quantity delivered all at once? Why is this? | Fractionated. It's a less harmful effect than if the radiation were delivered all at once. The body has a chance to repair itself between doses when it's fractionated. Whole body dose can depress many functions. |
| What percentage of human made radiation do medical & dental x-rays account for? | Medical & dental x-ray account for 90% of artificial man made radiation. |
| What is the only unit of measurement that expresses dose-effect relationship? | Rem |
| What is it called when an x-ray photon interacts with matter & disappears, as in the photoelectric effect? | Absorption |
| What is the minimum Pb equivalent for lead aprons. What does the NCRP recommend for Pb equivalent lead aprons? | 0.25 mm Pb equivalent is required for lead aprons. NCRP recommends 0.50 Pb equivalent. |
| What type of effects are those that will not occur below a particular threshold? What type of effects do not have a threshold dose & any dose can cause an effect, but increasing the dose may increase the likelihood of an effect? | Nonstochastic effects. Stochastic effects. |
| What limit may leakage radiation not exceed while the x-ray tube is operated at maximum potential? | 100 mR/hr @ 1 meter |
| Which of the following most effectively minimizes radiation exposure to the patient..... Small focal spot, Low ratio grids, Increased SID, High speed intensifying screens? Why is this? | High speed intensifying screens enable the use of lower mAs values, while increased SID requires higher mAs values. |
| In fluoroscopy, what must the x-ray intensity at the tabletop not exceed & at what kVp? | 2.1 R/min/mA @ 80 kVp |
| What is the HVL (Half Value Layer)? | The amount of material necessary to decrease the intensity of the beam to 1/2 its original value. |
| What radiographic exam is the highest radiation dose for a male & female? | Pelvis for male. L-Spine for female. |
| Which x-ray has the highest bone marrow dose? | The stomach & UGI tract are the highest with a 100 mrad "mean" dose. |
| What is the Use Factor? What is workload? | The % of time the primary beam is directed towards a particular wall. The # of x-ray exposures made per week. |
| What is the term for the reduction in x-ray photon intensity as it passes through material? | Attenuation |
| What is the process of radiation passing through tissue & depositing energy through ionization process? | Linear Energy Transfer (LET). |
| Which of the following will affect both the quality & quantity of the primary beam...HVL, kVp, mA? | The HVL. |
| Which of the following are the most radiosensitive.....Ova, Lymphocytes, Neurons, Myocytes. | Lymphocytes |
| What is the approximate intensity of the the scatter from a patient at 1 meter from them? What is the formula to figure out the intensity 1 m from the patient? | The intensity of the scattered radiation 1 meter from the patient is 0.1% of the entrance dose. Entrace Dose x .001 |
| The occupational dose limits is valid for which type of ionizing radiations? | Beta, X-radiation & Gamma radiation. |
| Are blood changes & erythmia considered early, or late effects of radiation exposure? Is carcinogenesis early, or late effects? Is carcinogenisis on a linear non threshold dos response, or linear threshold? | Early effects. Late effects. They are on a linear non threshold dose response. |
| What type of effects are non threshold & randomly occurring? What are some examples of these? | Stochastic effects. Carcinogenesis (development of cancer) & genetic effects. |
| What type of effects are predictable threshold responses? | Non stochastic responses |
| If a quantity of radiation is delivered to the body over a short period of time, will the effects be greater, or less than, if it were delivered over a long period of time? | The effects will be greater. |
| Are the extremities included in the whole body dose equivalent occupational limit? | No. |
| What is the total amount of filtration required in equipment & at what kVp? | 2.5 mm Al eq @ 70 kVp. |
| Which type of personnel monitor can provide an immediate reading? What is the disadvantage of this monitor? | Pocket Dosimeter (Pocket Ionization Chamber). It does not provide a permanent legal record. |
| Which of the following can be used to describe x-ray beam quality.....mA, HVL, kVp, Intensity, Dose rate? What is the principal (qualitative )factor of beam quality? | HVL & kVp both can be used to describe beam quality. kVp is the principal factor of beam quality. |
| Which of the following factors contribute to the amount of scattered radiation produced..... Radiation quality, field size, grid ratio? | Radiation quality (kVp) & Field size. |
| What factors affect the amount of radiation produced? How do these factors affect scatter produced? | X-ray beam quality (kVp), field size & tissue density. As kVp increases, scatter increases. As field size increases, amount of scatter increases. As tissue density increases (atomic #), amount of scatter increases. |
| What is the qualitative factor (weighting factor) of the following radiations.....fast neutrons, alpha particles, protons, Dx x-rays & gamma rays? What is the ranking of Relative Biological Effectiveness (RBE) from least damaging to most? | Dx x-ray & gamma rays 1, protons 5, fast neutrons 10, alpha particles 20. |
| What is the most radiosensitive portion of the GI tract? | The small bowel |
| Define Fractionation. Define Protraction. How do these affect the tissue effects from radiation damage? | Fractionation is when the dose is delivered in portions. Protraction is when the dose is delivered over time. When the dose is deliverd in portions over time, the less the tissue effect. |
| Where is Bremsstrahlung (Brems) radiation produced? Does is it start as an incident electron, or photon? Is there a loss of energy when Brems radiation is produced? Why is this? | At the Tungsten target of the tube. Starts as incident electron going towards the Tungsten target. The incedent e- is deflected from its course by attraction to the Tungsten nucleus & deflected with a loss of energy. The energy results in an x-ray photon. |
| What does an increase in HVL, or filtration also increase? | The overall avg. energy of the x-ray beam is also increased. |
| What are the effects of irradiation damage to macromoloecules? | Main-chain scission, cross-linking & point lesions. |
| What is the predominant radiation interaction in the body? Why is this? | Radioolysis. Since the body is made up of mostly (80%) water. |
| Which of the following are considered late effects of ionization radiation....leukemia, local tissue damage, malignant disease, genetic effects? | Leukemia, genetic effects & malignant disease |
| What are the major effects of DNA irradiation? | Chromosome abberation, cell death & malignant disease |
| What happens to the incident electron in the production of characteristic radiation at the Tungsten target? How is the x-ray photon produced? | It ejects an inner shell (K shell) Tungsten atom. When the outer shell (L shell) drop down to fill the K shell. L shell e- have higher energy level than K shell, so it gives up the binding energy as an x-ray photon. |
| What are the 2 type of radiation produced at the Tungsten target? | Characteristic radiation & Brems (Bremsstrahlung). |
| What is Hypoxic conditions? Anoxic? How does biologic material irradiated in these environments compare with a highly oxygenated state? | Hypoxic is low level oxygen. Anoxic is no oxygen. The higher the oxygen content, the more radiosensitive biologic material is, so both hypoxic & anoxic would be less radiosensitive than a highly oxygenated environment. |
| Does the TLD use a Lithium Fluoride phosphor? Are they reusable? Do they emit heat in response to stimulation by light? | Yes, Yes, Yes |
| What is the occupational yearly dose limit for students under 18 years of age? | 0.1 rem (100 mrem, or 1 mSv) in any given year. |
| The source to tabletop/skin distance in a fixed fluoroscopy unit must be no less than what? What about for a mobile fluoro unit? | No less than 15 inches for a fixed fluoroscopy unit. No less than 12 inches for a mobile unit. |
| The radiation dose to an individual depends on which of the following,....type of tissue interaction, qty of radiation, biologic differences? | All of them. |
| Which of the following are considered long term somatic effects to exposure of ionizing radiation.....life span shortening, cataractogenesis, carcinogenesis? | All of them |
| What is an acceptable ESE (Entrance Skin Exposure) for a PA chest radiograph? | 20 mR |
| Can mAs be decreased with the use of higher speed intensifying screen? Why? | The use of high speed intensifying screen increase radiographic density, so requires less mAs, and less exposure time. |
| Which of the following is most responsible for patient dose......Compton scatter, Classical scatter, Thompson scatter, Photoelectric effect? | Photoelectric effect |
| What is the TEDE (Total Effective Dose Equivalent) for occupational workers? | 50 mSv (5 rem) |
| What type of cells are Myelocytes?What type of cells are Myocytes? | Myelocytes are white blood cell precursor cells. Myocytes are mature muscle cells. |
| Are genetic alterations stochastic, or non stochastic? | Stochastic |
| What type of radiation effects are non threshold & randomly occurring? | Stochastic effects |
| What type of radiation effects are predictable threshold (requiring a certain qty of radiation to be received before an effect)? | Non Stochastic |
| The total # of x-ray photons produced at the target are contingent upon which....tube current, target material, square of kV? | All of them |
| How much of a difference in exposure factors would be making an exposure w/o a grid in comparison to an 8:1 grid be? | An 8:1 grid would require about a 4fold increase |
| What would the ESE (Entrance Skin Exposure) be for an abdomen x-ray? For a thoracic spine x-ray? | 375-698 mR for an abdomen. 290-485 mR for a thoracic spine. |
| Which of the following would be most likely to cause the greatest ESE (Entrance Skin Dose)....short SID, high kV, increased filtration, increased mA? | Short SID |
| As a generally accepted rule, what is the fluoroscopic skin dose that the patient received in fluoroscopy? | 2 rad/min/mA |
| Does increasing the kV applied to the x-ray tube increase the patient absorption? Why? | No. As kV increases, photon energy increases & patient absorption decreases. |
| What type of radiation is x-ray.....High LET low energy, Loe LET low Energy, Low LET high energy, High LET high energy? | It is low LET low energy |
| In radiation protection, the product of absorbed dose and the correct modifying factor (rad x QF) is used to determine...rem, curie, radiation quality, roentgen? | rem |
| Which unit of measure is used to express ionizing radiation dose to biologic material...rem, rad, roentgen, RBE? | rem. |
| How does filtration affect the primary beam.....increases the average energy of the primary beam, decreases the average energy of the primary beam, makes the primary beam more penetrating, increases the intensity of the primary beam? | It increases the average energy of the primary beam. |
| What is the term used to describe x-ray photon interaction with matter and the transference of part of the photon's energy to matter? | Scattering |
| The radiographer's radiation monitor report must include which of the following information....Lifetime dose equivalent, Quarterly dose equivalent, Inception date? | All of them |
| What quantity of radiation exposure to the reproductive organs is required to cause temporary infertility? | 200 rad |
| Which of the following is (are) possible long-term somatic effects of radiation exposure......blood changes, cataractogenesis, embryologic effects? | Cataractogenesis & embryologic effects are possible long-term somatic effects of radiation exposure. |
| Primary radiation barriers must be at least how high? | 7 feet high |
| Is it true that radiation with a low LET can contribute more to biologic damage than a high LET radiation? | No |
| Mutations are are examples of which....short term somatic effects, long term somatic effects, genetic effects, acute radiation syndrome? | Genetic effects |
| An area occupied by persona trained in radiation safety & wearing personnel monitoring devices is called which of the following....controlled area, uncontrolled area, off limits area, radiation area? | Radiation area |
| The exposure switch in an imaging room must keep the radiographer behind which of the following.....primary protective barrier, x-ray tube, door, 2ndry protective barrier? | The exposure switch in an imaging room must keep the radiographer behind the 2ndry protective barrier |
| The cascade process is associated with which of the follwing...Molybdenum targets, Brems radiation production, Characteristic radiation production, filtration effects? | Characteristic radiation production. The cascade of the electrons filling the shell below them that had an electron ejected. |
| Which of the following Acute Radiation Syndrome has the lowest whole body threshold dose......Carcinogenic syndrome, hematopoietic syndrome, GI syndrome, CNS syndrome? | Hematopoietic syndrome |
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jamestkelley
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