MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE.

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. Which site has been shown to have the smallest setup and alignment discrepancy? 1. brain 2. head and neck 3. extremities 4. pelvis 2. head and neck What is the term that defines radiation intensity at points equidistant around the source, normalized to the radiation intensity at a reference distance on the radius bisecting the source? 1. convergence function 2. kerma function 3. anisotropy function 4. sievert function 3. anisotropy function In the pediatric population, the least likely CNS tumor would be? 1. medulloblastoma 2. anaplastic astrocytoma 3. low grade astrocytoma 4. ependymoma 4. ependymoma In malignant tumors of the nasopharynx that spread directly to the middle cranial fossa, what is the usual route of invasion? 1. directly through the base of skull bone 2. foramen ovale 3. foramen lacerum 4. foramen rotundum 4. foramen rotundum What is output from a magnetron? 1. electrons 2. x-rays 3. microwaves 4. magnetism 3. microwaves Physical penumbra width is defined as? 1. total distance between max dose isodose curves at a depth 2. lateral distance between two isodose curves at a depth 3. physical distance between an area of dmax dose at depth 4. geometric distance between tramission dose at a depth 2. lateral distance between two isodose curves at a depth Nonlinearity in the range of CT numbers in tissue densities is due to? 1. change in mass number of the tissue 2. change in attenuation coefficient of the tissue 3. change in photoelectric interactions 4. change in the atomic number of the tissues 4. change in the atomic number of the tissues The measured and computer generated isodose curves should agree within? 1. 3%, 2mm 2. 2%, 3mm 3. 2%, 2mm 4. 3%, 3mm 3. 2%, 2mm Dose variation across the field at a specified depth is referred to as? 1. medial alignment 2. dose profile 3. beam profile 4. lateral alignment 3. beam profile Typically in a Tandem and Ovoid brachytherapy treatment the prescription is tied to point A. Where is Point A located? 1. 5cm sup to the lateral fornix, 2cm ant/post to the uterine canal 2. 2cm sup to the lateral fornix, 2cm ant/post to the uterine canal 3. 2cm sup to the lateral fornix, 2cm lateral of uterine canal 3. 2cm sup to the lateral fornix, 2cm lateral of uterine canal On Monday the Ir-192 HDR source activity is 6.67Ci with a treatment time of 800 seconds. What would be the approximate expected treatment time on Wednesday with source strength of 6.57Ci? 1. 788s 2. 800s 3. 806s 4. 812s 4. 812s An Ir-192 HDR source is being utilized in conjunction with a breast balloon for a breast treatment. What would be the typical prescription dose per fraction for this treatment? 1. 340cGy @ balloon surface 2. 340cGy @ 0.5cm from balloon surface 3. 340cGy @ 1.0cm from balloon surface 4. 340cGy @ 2.0cm from balloon surface 3. 340cGy @ 1.0cm from balloon surface An IMRT plan is prescribed 50.4 Gy to the 95% isodose line in a fractionation of 28 x 180 cGy. If two additional 180 cGy fractions are added, how will the magnitude of the maximum-dose point change relative to the prescription? 1. increase 2. no change 3. decrease 2. no change Electron boost fractions to the chestwall following mastectomy and primary photon treatments will generally require which beam modulator to aide in dose delivery? 1. lead shielding on the skin 2. tissue-equivalent bolus 3. diodes 4. infrared gating system 2. tissue-equivalent bolus The DVH is a graphical representation of? 1. dose per cc tissue, relative to a single structure 2. dose per kg tissue, weighted by tissue sensitivity 3. dose per cc tissue, relative to the whole body 4. dose per kg tissue, relative to the whole body 1. dose per cc tissue, relative to a single structure What are the 4 R's of Radiobiology? 1. Repair, Reassortment, Repopulation, Reoxygenation 2. Repair, Reassortment, Regeneration, Reoxygenation 3. Repair, Reassortment, Regeneration, Radiosensitivity 4. Repair, Reorganization, Repopulation, Reoxygenation 1. Repair, Reassortment, Repopulation, Reoxygenation Which cell type is most radiosensitive? 1. muscle 2. lymphocytes 3. bone 4. connective tissue 2. lymphocytes What is the approximate depth of 80% for a 12 MeV electron beam? 1. 1.2cm 2. 3cm 3. 6cm 4. 4cm 4. 4cm The LD50/60 for healthy young adult humans without medical intervention is? 1. 1-2Gy 2. 2-3Gy 3. 3-4Gy 4. 5-6Gy 3. 3-4Gy A total body dose on the order of 10 Gy (1,000 rad) of rays or its equivalent of neutrons commonly results in symptoms characteristic of the gastrointestinal syndrome culminating in death within? 1. prodromal, immediately 2. cerebrovascular, 24-48hours 3. gastrointestinal, 3-10days 4. hematopoietic, 30-60days 3. gastrointestinal, 3-10days With linac based SBRT/SABR and a plan that has a 100% maximum IDL, what is the typical range of prescription isodose line covering the PTV? 1. 40-60% 2. 60-90% 3. 90-100% 4. 100% 2. 60-90% According to quality assurance guidelines, the Light versus Radiation field congruence should agree to within? 1. 1mm 2. 2mm 3. 3mm 4. 4mm 2. 2mm Patient monitoring devices (TV system and intercom system) should be checked? 1. daily 2. weekly 3. monthly 4. annually 1. daily Identify the isotope used in brachytherapy that has an average energy of 30 keV? 1. gold-198 2. iodine-125 3. radon-222 4. iridium-192 2. iodine-125 Calculation for treatment room shield requires the following information? 1. number of patients per week x amount of radiation each patient 2. fraction of time areas will be occupied 3. fraction of time a beam is aimed at a certain wall 4. dose limits for occupied area 1. number of patients per week x amount of radiation each patient Monthly medical accelerator dosimetry tolerances for SRS/SBRT Planar KV imaging scaling (EPID) is? 1. /= 1mm 2. /= 2mm 3. baseline 4. functional 2. /= 2mm Name the specific DICOM information object definitions (IOD's) used to send information describing treatment plans, including prescriptions, fractionation and beam parameters? 1. RT Dose 2. RT Beam 3. RT Plan 4. RT Structure 3. RT Plan Prescriptions for dose and monitor unit calculations using Monte Carlo based treatment planning systems should be based on dose to? 1. a single voxel 2. an off axis point 3. target volumes 4. isocenter 3. target volumes Management of intrafraction respiratory motion during treatment allows? 1. image acquisition artifacts in the planning study 2. blurring of the static dose distribution for the tumor site 3. increased treatment margins for the PTV 4. reduced treatment volumes 3. increased treatment margins for the PTV Which of the methods used to reduce the impact of respiratory motion in radiotherapy results in a loss of resolution to tumor and normal organ delineation? 1. slow CT scanning 2. inhale and exhale breath-hold CT 3. four-dimensional CT 4. respiration-accelerated CT 1. slow CT scanning According to The AAPM Task Group 76 the use of respiratory management techniques is appropriate for the patients radiation treatment when? 1. when respiratory motion of the tumor is the same day to day 2. technique reduces treatment setup errors for patients 3. when tumor motion is greater than 5mm 4. allows physicians to identify microscopic disease 1. when respiratory motion of the tumor is the same day to day The most common Interaction for megavoltage photon beams in water-like tissues (Z = 7.5), is the _______ effect, which dominates (80%) for energies between 0.05 MeV and 10 MeV? 1. photoelectric 2. Compton 3. pair production 4. Rayleigh scattering 2. Compton When radiation passes through matter, the x-ray beam undergoes gradual reduction in the number of photons. This process is termed? 1. Bremsstrahlung 2. attenuation 3. thermionic emission 4. Compton scattering 2. attenuation Which of the following terms allows the manipulation of stored analog data to be presented in three dimensions? 1. resolution 2. voxels 3. pixels 4. matrix 2. voxels Head positioning for a patient with cancer of the maxillary antrium should be performed with the chin_________ to reduce exposure to the eyes? 1. neutral 2. extended superiorly 3. angles to the affected side 4. lowered inferiorly 2. extended superiorly The ratio of the dose rate of a given field size to the dose rate of the reference field size is? 1. relative output factor 2. back-scatter factor 3. percent depth dose 4. tissue maximum ratio 1. relative output factor During which stage of mitosis do the chromosomes align across the equator of the spindle fibers? 1. prophase 2. metaphase 3. anaphase 4. telophase 2. metaphase Data suggests that the greatest benefit for proton therapy would be in treatment of which type of tumors? 1. central nervous system 2. breast 3. pediatric 4. prostate 3. pediatric What does the term "oligometastes" refer to? 1. widespread metastases to multiple organs 2. limited metastases to one organ 3. solitary metastases 4. brain metastases only 2. limited metastases to one organ A beam degrader/spoiler is used in a photon beam for TBI in order to? 1. decrease beam energy 2. effectively hold lung transmission blocks close to patient 3. decrease background radiation 4. increase surface dose to the patient 4. increase surface dose to the patient Using magnetic resonance imaging (MRI) for treatment planning is useful since? 1. patient anatomy is geometrically accurate on the images 2. external contours are reliable 3. brightness of the image is related to tissue density 4. reliable for locating tumors within tissue 4. reliable for locating tumors within tissue A patient with lung cancer will be treated to 55 Gy to the mediastinum. In order not to exceed spinal cord tolerance, you could? 1. split course treatment giving 30Gy, two week split, then 25Gy 2. block the cord after 40Gy of treatments 3. deliver 120cGy BID to a total dose of 55 Gy 4. deliver 40Gy using AP-PA, then 15Gy using off-cord obliques 4. deliver 40Gy using AP-PA, then 15Gy using off-cord obliques Dose volume histograms (DVH) are useful to? 1. optimize beam angle selection 2. optimize radiation treatment in a reasonable time 3. give good representation of the dose to normal structures 4. indicate precise hot spot doses in a volume 3. give good representation of the dose to normal structures Which term refers to a volume enclosing subclinical microscopic disease in addition to a margin accounting for motion? 1. GTV 2. ITV 3. CTV 4. IM 2. ITV Which of the following would be considering a characteristic of an acceptable tandem and ovoid insertion on an AP radiograph? 1. tandem midway between ovoids 2. tandem deviated towards the bulky disease 3. ovoids low in the vaginal fornices 4. packing material between the ovoid and vaginal wall 1. tandem midway between ovoids Total body exposure to low level radiation (less than 10 cGy) may produce? 1. genetic effects 2. permanent sterility 3. GI syndrome 4. cataracts 1. genetic effects Candidates for accelerated partial breast irradiation include? 1. T1N0 primary 2. T2N0 primary 3. T3N0 primary 2. T2N0 primary A small area of high density near the surface of the patient would have the greatest impact on the dose near the edge of the high-density area with? 1. a single 6 MeV electron beam 2. a single 20 MeV electron beam 3. a single 6 MV photon beam 4. an IMRT beam arrangement 2. a single 20 MeV electron beam The mass attenuation coefficient depends on? 1. thickness of the material being attenuated 2. physical density of the material being attenuated 1. thickness of the material being attenuated Single whole body radiation exposure causes gastrointestinal syndrome, bone marrow syndrome and central nervous system syndrome at which of the following dose levels, respectively? 1. 50 Gy, 50 cGy, and 500 Gy 2. 20 Gy, 110 cGy, and 500 Gy 3. 2 Gy, 50 Gy, and 200 Gy 2. 20 Gy, 110 cGy, and 500 Gy Which of the following statements are true for Iodine-125? 1. half-life of 56.4 days 2. has a life long radiation protection issue 3. energy of 0.412 MeV 4. decays exclusively by electron capture 4. decays exclusively by electron capture The binding energy of the nucleus is? 1. inversely proportional to the atomic number 2. increases exponentially with atomic number 3. depends only on the number of protons 4. represents a mass defect in the nucleus 4. represents a mass defect in the nucleus Which factor affects the percentage depth dose of a given electron beam? 1. maximum energy 2. portal shape 3. nominal SSD 4. type of filter 2. portal shape Which of the following statement(s) is/are true concerning Negligible Individual Dose (NID) as defined by the National Council on Radiation Protection and Measurements (NCRP)? 1. a value of 0.01 mSv annually with no risk level 2. a value of 0.1 mSv annually with no risk level 1. a value of 0.01 mSv annually with no risk level The exposure to cGy conversion factor for air is? 1. the same regardless of photon energy 2. highest in the photoelectric energy range 3. highest in the Compton energy range 4. inversely related to photon energy 1. the same regardless of photon energy A "spike" in a differential DVH is called what? 1. delta function 2. standard basis vector 3. potential function 4. normal derivative 1. delta function The tissue-maximum ratio (TMR) may be derived by? 1. dividing tissue-air ratio (TAR) by backscatter factor (BSF) 2. dividing tissue-phantom ratio (TPR) by output factor 3. multiplying tissue-air ratio (TAR) by backscatter factor 1. dividing tissue-air ratio (TAR) by backscatter factor (BSF) According to ICRU Report #83, recommended dose prescribing and reporting for intensity modulated radiotherapy is based on? 1. absorbed dose at a point in the central portion of the PTV 2. absorbed dose at a point of the PTV at isocenter 3. absorbed dose and volume info from a DVH 3. absorbed dose and volume info from a DVH Prior to emerging through the accelerator window, the electron energy spectrum compared to the same beam at the patient surface is? 1. narrower 2. broader and lower in energy 3. dependent on the Z of the target 1. narrower