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MEDICAL PHYSICS ABR PART 1 CLINICAL LATEST
UPDATE 2025|300 ACTUAL QUESTIONS AND
ANSWERS 100% CORRECT |A+ GRADED
Rate the body systems in order of decreasing radio-sensitivity.
- Hematopoietic, Reproductive (2-5 Gy)
- Skin, cornea, lens of eyes, GI organs (10 Gy)
- Bone and cartilage
- Lungs, kidneys, Liver, Pancreas
- Muscle, brain, nerves, spinal cord (20 Gy) a. What are the components of the cell cycle & their order? b. What is the relative radio-sensitivity of each? Mitosis (M), Gap 1 (G1), Synthesis (S), Gap 2 (G2) a. M -> G1 -> S -> G b. M > G2 > G1 > S Cerebellum:
a. Function b. Location a. Motor control, balance b. Directly posterior to the brain stem. Cerebrum: a. Function and properties b. Divisions a. Higher functions: thought, action. b. 4 lobes: frontal (anterior), parietal (superior), occipital (posterior), temporal (lateral x 2). Cerebral cortex Sheet of neural tissue outermost to the cerebrum. Grey matter Brain steam function Basic vital life functions (breathing, heartbeat, etc.
Lower gastrointestinal LGI. Small and Large intestine. Stool. US transducers: a. What is the angle of orientation of the two surfaces? b. How thick are the transducers in terms of the wavelength? c. Are the pressure waves and voltage in phase or out of phase? a. 180 degrees. b. lambda/ c. pressure: in phase. Voltage: out of phase. Stroke a. Describe b. Effects a. sudden loss of consciousness resulting when the rupture or occlusion of a blood vessel leads to oxygen lack in the brain b. Loss of brain function, ischemia, hemorrhage
Ischemia Insufficient blood flow to an area Hemorrhage Flow of blood from a ruptured blood vessels. Transurethral resection Small pieces of tissue from a nearby structure (typically prostate) are removed through the wall of the urethra. Foramen magnum A large hole in the occipital bone (base of skull) for the passage of nerves into the spinal cord. Liver cirrhosis a. Describe b. Causes
Haploid cells A cell containing only one set of chromosomes. Diploid Cell having two sets of chromosomes or twice the haploid number. How many essential minerals to human health. List them.
7 major: Calcium, Sodium, Chloride, Magnesium... Phosphorus, Sulfur, Potassium. 10 trace: Manganese, Chromium, Copper, Selenium... Zinc, Iodine, Fluoride, Molybdenum. {Sing Mexican Hat Dance. Iodine = "EyeDine"} How many and what are the major elements of the body?
H (63%)
O (26%)
C (9%)
N (1%)
Number of Cranial (CNS) nerves 12 types (but are paired, so 24 total) Oh Once One Takes The Anatomy Final Very Good Vacations Are Here. What are the thresholds for whole body acute radiation (rem/rad or Sv/Gy) for given symptoms? rem <=> rad; Sv <=> Gy 50 rem (0.5 Sv): Blood count change 100 rem (1 Sv): Vomiting 150 rem (1.5 Sv): Death threshold 350 rem (3.5 Sv): LD 50/60 with minimal care 500 (5 Sv): LD 50/60 with supportive medical care 1000 (10 Sv): LD 50/60 with intensive medical care (bone marrow transplant) *LD 50/60 is the lethal dose at which 50% of those exposed die within 60 days.
Prolactinoma A benign tumor (adenoma) of the pituitary gland that causes it to produce too much prolactin Vertebral level of the Larynx C Meningioma A tumor arising in the meninges, the structure surrounding the brain and spinal cord Hydrolysis produces what? H+, OH-. Leads to H2O2 (relatively stable). OH- highly oxidizing/damaging. Lens dose equivalent
The external exposure dose equivalent to the lens of the eye at a tissue depth of 0.3 centimeters (300 mg/cm2). Transport index Max dose equivalent rate at one meter from the surface of a package containing radioactive material. 4 Rs of Radiobiology. Used to justify fractionation.
. Redistribution . Repair . Reoxygenation . Repopulation . (Radiosensitivity) {DPOPS} What is the effect of ionizing radiation on the cellular level. Damage to DNA.
Choroid plexus A highly vascular portion of the lining of the ventricles in the brain that secretes cerebrospinal fluid (CSF) which cushions brain and spinal cord. Optic Chiasm The crossing of the optic nerves from the two eyes at the base of the brain. Below the hypothalamus. What systems are responsible for equilibrium? Vestibular system (inner ear) and Cerebellum Synovial fluid Lubricates, nourishes, and keeps the joint moveable Single Hit Theory (Equation and variable definitions)
S = N/N0 = e^(-D/D0) S: Survival fraction N: Cells remaining N0: Initial # of cells D: Given dose D0: Mean lethal dose Metastasis Spread of cancer cells beyond their original site in the body Sestamibi Scan Tc99m is injected intravenously and traced to heart muscle or thyroid to observe function. Emits 140 keV gamma rays (same as standard x- ray equipment). Peritoneum Double-layered membrane surrounding the abdominal organs.
L
Number of each type of vertebrae Cervical (7) Thoracic (12) Lumbar (5) Sacrum (1, *5) Coccyx (1, *4) a. What is Multiple Sclerosis b. Best technique for imaging Multiple Sclerosis? Why? a.CNS disease. The body's own defense system attacks myelin. b. MRI a. Which cancer has the shortest latency period? b. How long? c. How relates to others? a. Leukemia b. 2-15 yrs
c. Others 10-30 yrs http://www.hicare.jp/en/09/hi04.html Radiation equivalent man <-> Severt conversion 100 rem = 1 Sv What is the prob. of genetic defects to offspring as a function of dose? Approx. 1/10,000 at 10 mSv Or 1% per Sv. Risks of radiation exposure at stages of gestation (weeks)? 1 week: Lethality 2-7 weeks: Gross malformations, Growth retardation, general neuropathology 8-15 weeks: Mental Retardation most, but also Growth retardation, Sterility 16-25 weeks: lower risk of all above except lethality.
Nausea and vomiting. Stereotactic radiosurgery is best used for what? Tumors of the brain. Stenosis Abnormal narrowing of a bodily canal or passageway {A stent will prevent stenosis} What is the primary mechanism for damage by LET photons? Hydrolysis. 2/3 of damage to DNA by hydroxyl radical. Medical term for mouth. Buccal cavity. Vena cava
Either of two large veins that return oxygen-depleted blood to the right atrium of the heart. Pulmonary artery One of two arteries that carry venous blood from the heart to the lungs What is a barium scan used for? Contrast for visualization of the GI tract via x-ray. Committed dose equivalent Dose to a specific organ or tissue that is received from an intake of radioactive material by an individual during the 50-year period following the intake. Circle of Willis A circle of arteries at the base of the brain that supply blood to the brain. Surrounds the pituitary.
