MDCb

This document includes practice exam questions for the MDCB exam, covering key concepts, procedures, and knowledge areas required for successful certification. All questions are paired with correct answers, making it a useful resource for focused review and exam preparation

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. A What is the approximate density of healthy lung tissue? A. 0.30 g/cc B. 0.95 g/cc C. 1.00 g/cc D. 1.03 g/cc B 2. The accelerator component that injects electrons into the linear accelerator is: A. a klystron. B. an electron gun. C. a bending magnet. D. a thyratron. D The equivalent square of a rectangular field of dimensions X xY is: A. The square root of 4 x X x Y B. 2 x (X x Y) C. (4 x X x Y) / (X + Y) D. 2 x (X x Y) / (X + ...

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. WAN stands for: A. Wide Area Network B. World Area Network C. Wide Artificial Network D. Wide Access Network A Field uniformity can be checked by measuring: A. field size dependence of output B. beam output C. flatness & symmetry D. light field coincidence against gantry angulation C The isocenter of a clinical linac can be checked by: A. optical means B. mechanical means C. radiation means D. all of the a...

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. When an enface electron beam is used for chest wall irradiation, which of the following described the dose at the interface between the chest wall and lung? A. decreased due to reduced scatter from the lung B. decreased due to irregular surface contour effects C. increased due to an increase in the electron fluence D. increased due to a larger angle of electron scatter E. unchanged from that in a homogeneous phantom A A beam deg...

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. A patient receiving treatment to the head and neck region has experienced a skin reaction and mucositis at a total dose much lower than anticipated. The radiation oncologist requests an evaluation of the treatment. Which of the following steps should be taken? A. recalculate the treatment plan B. ensure that the depth dose, build-up region, wedge parameters, and other pertinent information for the treatment unit are correct C. review th...

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. Is the dipeptide soluble in water (base your answer on the properties of the side chains, not the NH3+ and CO2- groups on the ends of the dipeptide)? No Which level of protein structure relies exclusively on interactions between peptide groups? Secondary Where would you expect to find a dipeptide with R groups (side chains), in the cell? Cytoplasm Sickle cell anemia is caused by a mutation in the gene encoding Beta-globin. This mutation ca...

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. electronegativity is larger/smaller with a greater number of electrons in the shell. smaller electronegativity us lager/smaller with a greater number of protons in a given period. larger List 4 pairs of 2 atoms that will create a polar covalent bond using H, C, O, N C-O, H-O, N-H, C-N In the box below, indicate what is wrong, if anything, with the following statement. If it is correct, write "nothing, it is correct". If it is incorre...

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. anisotrop...

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. Which of the following CT numbers (Hounsfield units) is most closely related to lung tissue? 1. -1000 2. -750 3. 0 4. +1000 2. -750 Which of the following CT numbers (Hounsfield units) is most closely related to air? 1. -1000 2. -750 3. 0 4. +1000 1. -1000 Parent and daughter radioactive isotopes are said to be in secular equilibrium when they? 1. are equal in atomic weight 2. have the same half-life 3. have a constant ratio...

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. High dose rate (HDR) remote afterloading can be used to treat which of the following sites? 1. glioblastoma 2. leukemia 3. Hodgkin's lymphoma 4. cervix 4. cervix Lipowitz metal is used in place of lead to make custom shielding blocks for which reason? 1. provides a sharper beam edge 2. requires less block thickness 3. produces lighter blocks 4. has a lower melting point 4. has a lower melting point To dose of which area would ...

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. In TG 43, what variable is known as F? Anisotropy: provides dose falloff info using attenuation and scatter only perpendicular to the radial dose function This would be the "along" portion on the along and away tables, rotation away from central axis Steps done to complete a survey of an HDR brachytherapy procedure using an ion chamber survey meter? 1st. Before treatment survey of afterloader to confirm source is contained 2nd. Ac...

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. Rule of thumb for proton attenuation? Protons will lose about 10 MeV per cm Typical treatment energy range for protons? From 80 MeV to 250 MeV What are the three dominant photon interactions in radiation oncology? Photoelectric Effect, Compton Scattering (incoherent scattering), and Pair Production What determines the energy of a released electron during the photoelectric effect? Energy of electron = energy of incoming photon - binding en...

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. What is a half-life? Time it takes for a particular quantity (activity) to reduce to 50% What is the decay constant (lambda) formula? lambda = ln(2) / half-life What is the mean life formula? mean life = 1.44 (half-life) What is the formula for radioactive decay? A=A0 e^(-λt) Half-life of Pd-103? 17 days Half-life of I-125? 59.4 days Half-life of Ir-192? 73.8 days Half-life of Cs-137? 30.2 years Half-life of Co-60? 5.26 years ...

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. The energy equivalent of an atomic mass unit is: (A) 0.5 MeV. (B) 1.0 MeV. (C) 931.0 MeV. (D) 1000.0 keV. (C) 931.0 MeV. Which of the following describe(s) the Becquerel (Bq)? (A) 3.7 x 108 mCi (B) 3.7 x 1010 mCi (C) 2.7 x 10-8mCi (D) 2.7 x 10-10mCi (C) 2.7 x 10-8mCi The best way to reduce dose to a patient's right optic nerve while treating a right lacrimal gland tumor with non-coplanar 6 MV photons is to instruct the patient to:...

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. The measured and computer generated isodose curves should agree within: A. +/- 3%, 2mm. B. +/- 2%, 3mm. C. +/- 2%, 2mm. D. +/- 3%, 3mm. C. +/- 2%, 2mm. Dose variation across the field at a specified depth is referred to as: A. medial alignment B. dose profile C. beam profile D. lateral alignment C. beam profile An Ir-192 HDR source is being utilized in conjunction with a breast balloon for a breast treatment. What would be the typica...

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. According to QUANTEC guidelines, in order to avoid a 5% risk of dysfuntion, less than 55% of the volume of Kidneys should receive what dose? A. 6 Gy B. 12 Gy C. 24 Gy D. 32 Gy B. 12 Gy According to QUANTEC guidelines, what rate of spinal cord myelopathy would be expected if 70 Gy were delivered to the spinal cord with conventional fractionation of 2 Gy per day? A. < 5% B. 20% C. 50% D. 100% C. 50% A radiation oncologist is designi...

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. The minimum nominal distance a tissue compensator should be placed from the skin surface without affecting the skin sparing effect is: A. 5.0 cm. B. 10.0 cm. C. 20.0 cm. D. 25.0 cm. C. 20.0 cm. The radiation therapy technique which utilizes many shaped beams which may NOT conform to the target volume to achieve a highly conformal distribution is: A. conventional forward treatment planning. B. intensity modulated radiation therapy (IMRT)....

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. Although they receive the same dose, some tissues exhibit acute radiation damage earlier than others because they have a: A. smaller number of metabolizing cells. B. reduced blood flow. C. lower number of hypoxic cells. D. higher mitotic index. D. higher mitotic index. Unless otherwise permitted by the NRC, brachytherapy needles and tubes must be leak tested by the user at intervals NOT to exceed: A. 1 month. B. 3 months. C. 6 months. ...

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. Extra consideration of immobilization for SBRT patients is needed due to: A. rapid dose falloff. B. length of treatment time. C. multiple beams. D. increased imaging time. A. rapid dose falloff. What lead thickness is required to reduce the transmission to less than 5 percent for a 12.5 x 12.5 cm2, with a 12 MeV electron field? A. 1.2 mm B. 3.0 mm C. 5.6 mm D. 8.0 mm C. 5.6 mm Brachytherapy cervix applicators are often made of titani...

MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED GUIDE. What factors are instrumental in determining the dose uniformity in equally weighted parallel opposed beams? A. beam energy, tissue inhomogeneity and patient thickness B. beam energy, patient thickness and tissue maximum ratio C. beam flatness, patient thickness and collimator scatter D. patient thickness, inhomogeneity and collimator scatter A. beam energy, tissue inhomogeneity and patient thickness Two adjacent electron fields are to be ...