2D isotope scanning Flashcards
2D isotope scanning
A radionuclide generator is a source of radionuclides for radiopharmaceuticals. The most commonly used generator in Nuclear Medicine is the is (technetium-99metastable/Molybdenum-99) 99Mo/99mTc generator. It has a short half-life (6 hours), can be easily manufactured. Technetium-99m is used as a radioactive tracer and can be detected in the body by medical equipment (gamma cameras). It is well suited to the role, because it emits readily detectable gamma rays.
When complexed to methylenediorthophophonate (MDP), Tc99m is incorporated in broken bones; a radioactive tracer may view this radioactive blood pooling, indicating a broken bone. Soft tissue doesn’t uptake Tc99m
Tc-sulphur colloid is used in BRCA sentinel lymph node treatment.
Ultrasound
Ultrasound waves reach an object or surface with a different texture and a wave is reflected back. Ultrasound waves are not ionising, but do not penetrate gas or bone, so gaseous areas of the body (lung, bowel) and any bone structures cannot be observed using this method. Solid organs, muscles and tendons may be observed and they are utilised in foetal examinations.
X-rays
X-rays blacken photographic film; more dense structures (bone) appear white and less dense structures (soft-tissue, fat) appear black. X-rays are used to confirm bone fractures or breaks. It is a non-invasive, ionising imaging technique.
Hydroxyapatite is what bone is made from- phosphate salt of calcium.
Computer Tomography
CT scans show a slice, or cross-section, of the body. X-ray images result from attenuation of the X-rays by the material through which they pass. Attenuation is the removal of X-rays from a beam, by absorbing or scattering them; the greater the density of a material, the greater it absorbs/scatters X-rays. The image shows your bones, organs, and soft tissues more clearly than standard x-rays. X-ray computer tomography uses massive doses of ionising radiation; effective dose of head CT is 100 times greater, chest CT is 300 times greater and abdominal CT is 400 times greater.
Mammograms
Ionising radiation (lower-energy X-Rays) is used as a complement to ultrasound, ductography, positron emission mammography (PEM), and magnetic resonance imaging (MRI), to give an X-ray image of breast tissue. Parallel plates are used to compress breast tissue to reduce exposure and scatter X-rays.
Magnetic resonance imaging (MRI)
MRIs produce far more detailed images of the structure of a patient’s blood vessels, nerves, bones, and organ. An MRI takes pictures of places in your body that contain water, and the detail in these images comes from the ways that different tissues interfere with the electromagnetic waves coming from water molecules. Protons are aligned parallel (lower-energy state, preferred) or anti-parallel. A very strong, constant magnetic field forms that remains in place for the duration of the measurement, and this super-strong field makes all the protons try to line up with the poles of the field. The MRI machine intentionally disrupts this field by sending a brief pulse of an additional, weaker electromagnetic field. This weaker pulse points in a different direction than the constant magnetic field, and so it disrupts the protons so that they become misaligned with the constant field. Because different places in the body contain different amounts of water, MRI detects the electromagnetic fields of the atoms in water molecules and uses this to determine differences in the density and shape of tissues throughout the body.
PET
A positron (ß+ decay) travels a short distance before colliding with an electron of a nearby atom leading to annihilation, where 2 gamma rays (photons) are produced, emitted at 180º to one another. The photons are detected by an external gamma camera. 18F-FDG (18F-fluorodeoxyglucose) is the most commonly used PET radiopharmaceutical. It has a half-life of 110 minutes, allowing it to be transported around the body. FDG is used to measure the rate of glucose metabolism useful for cardiac studies, tumour localisation and quantitation, differentiating between benign and malignant tumours, and monitoring tumour therapy.
PET-CT
Combination of PET (metabolic imaging) with CT (anatomical imaging) to produce a single image detailing anatomic structure and metabolic function to accurately observe abnormalities.
Sterilisation of devices
Bandages, scalpels, stents, needles & cannulas can be sterilised using gamma rays. Side effects of treatment Hair loss Fatigue Changes to appearance: reconstruction? When?? Clothing??? Lymphoedema Menopausal symptoms Fertility issues
Changes to body
Ongoing hot flushes & mood swings
Vaginal dryness (because of lower oestrogen levels)
Sexuality: period of adjustment – not talked about as much as other side effects but can be just as debilitating
Anxiety
Depression 25% women diagnosed with breast cancer suffer significantly - require medication /CBT or other structured psychological help
