Unsealed sources Flashcards
osteoclasts =
clear away
osteoblasts =
build up
Batson Venous System (BVS)
diffusion through this system is the principle of spinal mets, spread is possible through arterial, lymphatic or locality
describe the communication between the external and iliac veins
there is abundant communications through the pelvic venous plexus which provides various collateral routes between the external and iliac veins. The venous drainage passes through the vertebrae destroying the body from the inside
where is VBS found
near the spine, blood borne spread causes lumbar mets during prostatic disease
where are osteoclasts derived from
monocytes in the bone marrow
what do osteoclasts do
wok on the outer layer, destroying the bone lining
what work as a team
osteoclasts and oesteoblasts
where are osteoblasts from
cells associated with blood vessels, once these are active they produce osteoid which is mainly made up of collagen.
what does mineral crystallise around the collagen scaffold form
hydroxyapatite crystal which contains calcium phosphate
what do osteoblasts form
new bone which becomes embedded within the matrix and differentiates into osteocytes
what does the bone composition allow for
calcium reservoir which provides support and locomotion
the role of osteoclasts
liberate minerals and molecules which are stored in the matrix, anchor the surface of the bone and create a microenvironment underneath - sealed zone. Creates an acidic environment, therefore bone is broken down dissolving the bone mineral content. Enzymes released from the oestoclasts remove the remaining collagen
bone mets
occur frequently in prostate, breast, lung patients
disruption in the osteoclasts and osteoblast balance causing pathological fractures and cord compression
associated with continuous pain or arises during movement
anti-inflammatory
EBRT local or more locally extensive
what happens once cancer arise in the bone
produce growth factors which stimulate osteoblastic or osetolytic activity which results in bone remodelling, the release of other growth factors leads to a cycle of bone destruction and growth of local tumour resulting in numerous sclerotic [hole] mets
nuclear medicine function
diagnosis, staging, follow up
determine tumour location, size and extent
staging: treatment options will differ dependent on the outcome
standard follow up is 5 years, the duration is dependent on the risk
MDP
a compound which attaches to the crystal (chemiabsorption) due to being attracted to the crystal. Tc-99m is the radioactive label which works alongside (half life of 6 hours). It emits gamma rays.
The m stands for metastable therefore once these rays are emitted it becomes Tc-99. A gamma camera is used to visualise the gamma rays. During primary excretion the amount of radionuclide within soft tissue decreases to 50% with 50% in the urinary system and 50% in bone
what is the degree of uptake dependent on
blood flow and rate of new bone formation
patient prep for a bone scan
drink plenty of water: flushes the system
all metal objects to be removed: blocks the gamma rays, creating a hole in the scan
if the radionuclide is transmitted to another area it will create a photon increased area
empty bladder: gamma rays block everything else
what is the RP and route of administration at a bone scan
500MBq Tc-99m MDP injected into the median cubital chin
what are the three phase images
flow phase
blood pool phase
delayed phase
flow phase
in the first 2-5 seconds, images are obtained for 60 seconds demonstrates blood flow, circulation and perfusion
