Dis Flashcards
examples of negative and positive contrast media
Negative contrast media =Air,CO2,O2 (because they are radiolucent)
Positive contrast media= iodine, barium, gadolinium (they are radiopaque as they have a high atomic number)
What are the benefits of barium surface
High atomic number, cheap, non toxic, inert, good coating properties, deforming agent added(no bubbles), dispersing agent added so even distribution of particles.
What does the intraoral tube head contain
Stationary anode
High tention transformer
Tube filament transformer
T1vsT2?
T1=fluid is dark
T2=fluid is bright
Brain imaging why no xray?
Doesn’t show brain injury if skull fracture whereas on ct and mri it does.
What is the treatment for brain tumours
Surgery, radiation therapy chemotherapy and drug therapy
What are indications for hysterosalphongogram
Infertility, check post surgery, recorering spontaneous abortions
What is needed for a hestereosalpheogram
Speculum, forceps,towels, swabs, catheter, contrast media, syringe
What are renal calci and cause
Kidneystones, dehydration
Prep for urtherohraphy
3 step ID
Consent
Explanation
Empty bladder
Gown put on
What are clinical indicators for urethrography?
Strictures,
Fistula
Abnormality
Difficulty passing urine
Blood from urethra
Trauma
(What it might indicate/show)
(Only done on male paitents)
Symptoms of bladder problems
Pain
Pain peeing
Difficulty peeing
Unusual pee frequency
Many pee infections
HSG patient prep
ID and consent, full explanation, timing to 5-10th day of menstrual cycle, change into gown, empty bladder, LMP form
What is HSG exam
Exam of reproductive tract with speculum, for pregnancy, miscarriage, check post surgery, infertility
Complications of HSG exam
Trauma to vagina or cervix
Abdominal cramps
Bleeding
Infection
CT: important properties for detection
High dynamic efficiency
High dynamic range
Narrow gaps between elements
Fast response
Low cost
Small size
What is the radiological protocol?
The type of CT exam that best suits the clinical question and patient presentation
CT: What is in between the tube and the patient
Tube
Bow tie filter
Collimator
Patient
Detector
CT: why use spiral over sequential?
Dismiss breathing or motion, optimise contrast utilation, reconstruct any position, scan is fast
What is the CT protocol
Set of parameters that specify a specific exam and contrast delivery requirements
Describe a 3rd generation CT scanner
X Ray beam hits a row of detectors, then they both rotate to image a different angle, repeated until a single slice is scanned, then the array is moved to a different slice
What is the toilet roll in the ct called
Gantry
Phases of contrast injection
Non contrast phase
Early arterial phase
Portal Venus phase
Hephrogenic phase
Excretory phase
What is commonly used as a radioactive tracker in nuclear medicine
An isotope of 99TC (technitium)
(A metastable nuclear isomer with a half life of 6 hours)
What is physical and biological half life
PhysicL : the length of time for a radioactive substance to decay to half its level of activity
Biological: the length of time it take the body to expell a substance
Combined it is the effective half life
What is the radioactive tracker detected with
Gamma camera
What is PET
Position emission tomography:
Allows non invasive quantative assessment of biochemical and functional processes
PET scan patient preperation
Relaxed, hydrated
Fasted for 6hours
Consent
ID
1 hour uptake in a darkened room
Empty bladder
(20 to 30 minuet scan and results within 48h to referee)
How to reduce dose in nuclear medicine
Distance (imaging camera positioned as far away from the operator as possible, using tongs to handle sources, hot waiting area, controlled areas)
Time (minimise time spent with the patient once injected, full explanation before injection, no waiting around in hot areas, efficent use of time)
Shielding (use shielding wherever appropriate and possible, syringe guards, locked and lead lined decay storage for waste, disposal of shares into shielded bin)
Hazards with liquid helium
Helium leaks may escape into magnet room creating a risk of asphyxiation (oxygen alarms fitted)
What is a quench
Where liquid helium rapidly bois off slowly eliminating the magnetic field, can be spontaneous or deliberate, expensive, magnet downtime 5+ days, helium escapes through pipes and doors open outwards to prevent explosion
Other hazards in mri
Projectiles, implants, tissue or nerve stimulation, acoustic noise, specific absorption rate, burns, matnetohydrodynamic effect
Controll of risk in mri
Mri safty questionnaire for everyone entering mri environment , controlled areas, authorised personnel only,
What is the magnetohydrodynamic effect
When an electrically conducive fluid (blood) moves within a magnetic field an electrical current is produced.
Vertigo, nausea, phosphenes, worse at high fields, staff may experience dizziness when leaning into rhe bore of the magnet
Advantages and disadvantages to a permanent magnet (the burger one)
Small static field so can be close to public areas, open mri is more coumftable for patients, lack of need for liquid helium,
X heavy compared to superconducting systems
There are some superconducting Mri with open configuration
Advantages and disadvantages of resistive magnet (the standing one)
Magnet can be switched on or off, open mri so patients are more coumftable, lack of need for liquid helium,
X more expensive to run because more electricity used
X low field strength
Advantages and disadvantages of superconducting magnet (toilet roll one)
Significantly higher field strengths, faster, most common, some open configurations available,
X expensive, more anxious for patients, higher field strengths
Mri patient preparation
Controlled area door: inroduce self, ID, consent, screen form, check for implants
Pairent prep area: take weight and height, change patient cloths, get rid of metal, cannulation, Mr safe wheelchair or bed,
Magnet room: earplugs and headphones, contact buzzer, pads between cables and bare skin, position patient on magnet couch, hands and legs not crossed,
Control room: check patient can hear over intercom, music?, warn about noise ,
What are the probes in ultrasound
Curvilinear(curved so can be angled under the ribs, used for general and obstetrics), linear(used for vascular work), transvaginal
Patient preparation for ultrasound
Full bladder: acts as an ausoutic window for pelvic exams
Fasted: for liver and gallbladder exams, allows gb to be filled with bile so the wall and contense are visible
Sometimes no preparation
What is the purpose of the 12 week scan?
Determain viability
Exclude ectopic pregnancy
Exclude twins
Confirm gestation
Exclude Abnormalitys
Rule out ovarian pathology
Exclude uterine pathologies
Purpose of the third trimester scan
Cheak:
Growth
Placental site
Follow up of Abnormalitys
Amniotic fluid volume
Doppler umbilical artery
Presentation
What processes and patient preparation are required for a contrast enhanced CT Chest/Abdomen/Pelvis from referral to scan (OSCE 15MARKS)
B) Patient preparation for CT CAP
Justified by radiologist
Three point check to identify patient
LMP, as appropriate ? tampon for female patients, if pelvic area being scanned
Explain procedure
Contrast injection?
Pre-procedure checks
Effects
Change into gown
Remove jewellery/metal objects from area
For chest/abdo, and for C/A/P, depending on pathology
Oral contrast
Mixed with water, to make 900mls
Abdo = “half prep” – half the amount 450mls , 30 minutes before scan
Abdo/pelvis = “full prep” – all of it 900mls , 60 minutes before scan
Keep half a glass back for just as patient goes on table
For ca oesophagus and and ca pancreas
At least 500mls 30 minutes before, and glass just as patient goes on table
100mls intravenous contrast, e.g. Optiray 300, 3mls/sec, pump driver
What are the patient aftercare requirements and considerations for a patient post CT Pneumocolon (OSCE 15 MARKS)
Keep patient in department for 20 mins post procedure, leave cannula in situ for duration of recovery period, this is so that if the patient becomes unwell there is venous access for emergency treatment,
Signpost toilet to patient ,
Offer tea/coffee/biscuit during recovery period, make sure the patient is warm (supply blanket if necessary) or allow patient to dress, Closely observe patient during 20 minute recovery period,
Advise return to normal eating and drinking pattern when discharged and recommend that patient drinks plenty of fluids for the following 2-3 days
Warn of possible tummy cramps (flatulence)
Blurring of vision following buscopan (usually 30 mins duration)
Advise where/when results will be received by patient
If severe abdo pain or unwell, seek medical help, remove cannula prior to discharge, following aseptic technique, by wearing PPE
Briefly describe the construction and function of Orthopantomography (OPG) equipment. (OSCE 15MARKS)
Sectional images, produced by moving equipment
X-ray tube and image receptor linked, so they move around a central pivot/fulcrum - patient’s head
Moving x-ray tube ‘blurs out’ shadow of overlying structures, by placing dental arch in axis of tomographic movement,
X-ray beam very tightly collimated into a narrow fan shape beam by a slit aperture at the tube head,
X-ray beam angled upwards by approx 7-8° to avoid superimposition of some anatomical structures,
Focal spot typically 0.6 mm,The rotation of the beam is not linear, but is modified to allow for the elliptical dental arch; equipment follows a few different centres of rotation (often 3) to compensate for this anatomy,
‘opens out’ image of dental arch to appear in linear arrangement on final image,
Control panel - select kV and mA (now usually pre-programmed), adjust the height of the equipment/position of the bite peg (using laser lights), etc
Different programmes, e.g. full OPG, adult v child; TMJ’s, trauma mandible, etc.Average exposure time ~15 secs , so immobilisation essential
Patient immobilisation – head clamps, chin support/bite rod, handles, etc.
Digital software – image manipulation, measurements, comparison images during treatment regime, etc.
Hh
