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Imaging science and technology > nuclear med > Flashcards

nuclear med Flashcards

1
Q

radiopharmaceutical

A

radioactive substance used in nuclear med imaging / treatment

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2
Q

tracer

A

another name for radiopharmaceutical

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3
Q

uptake

A

absorption / accumulation of a radiopharmaceutical by an organ or tissue indicating function / activity

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4
Q

activity

A

the number of radioactive decays per second measured in becquerels or curies

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5
Q

emission

A

release of energy or particles e.g. gamma rays, from a radioactive substance

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6
Q

scintigraphy

A

process of creating images using gamma camera to detect radiation emitted by radiopharmaceutical

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7
Q

hot spot / cold spot

A

hot spot- area of increased uptake of the radiopharmacetucal, indicating higher activity

cold spot- area with reduced uptake, indicating low activity or damage

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8
Q

contamination

A

unintended spread of radioactive materials on surfaces, equipment or personnel.

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9
Q

isotopes

A

atoms of the same element with the same no. of protons but different number of neutrons. this means same atomic number but different atomic masses

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10
Q

stable v unstable isotopes: basis for radioactivity

A

stable nuclei- balanced protons and neutrons
unstable nuclei- imbalance between protons and neutrons which causes instability

atoms with unstable nuclei release more radiation to achieve stability

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11
Q

radioactive decay-

A

radioactive atom becomes more stable by releasing particles and energy- this is called radioactive decay

-nuclei become stable through different radioactive decay as charged particles or photons

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12
Q

types of radiation - alpha

A

-2 protons and 2 neutrons- has no electrons
-relatively large, can’t penetrate very far into other materials
-strongly ionising: easily knock electrons off any atoms they collide with

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13
Q

types of radiation- beta

A

electrons- charge of -1 and has no mass
moderatley ionising as it is small- 5mm of aluminium

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14
Q

types of radiation: gamma

A

-waves of electromagnetic radiation
-no mass or charge- can pass through materials
-weakly ionising, can travel long distances and can be stopped by thick sheets of lead
-emitted from a nucleus

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15
Q

half life

A

time it takes for activity of the source to fall to half its original value

-short half life- (Tc-99m) ideal for imaging as there’s minimal patient exposure

-longer half life- (I-131) suitable for therapeutic purposes

e.g. tc-99m, 6 hour half life
after 6 hours, 50% of the isotope remains, after 12 hours only 25% remains

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16
Q

how are isotopes produced

A

-cyclotron- machine that accelerates charged particles using magnetic fields. creates isotopes like fluorine-18 which has a very short half life. requiring quick use after production, and is often located near hospitals to minimise decay during transport.

nuclear reactor- produces isotopes e.g. molybdenum-99, parent isotope for Tc-99m . exposes suitable target material to the intense reactor neutron flux for an appropriate time
generator

generator: portable system that extracts Tc-99m daily from parent MO-99 (parent)- separates decay product from the source radionuclide.

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17
Q

why are generators often used to create isotopes?

A

portable and easy to use in hospitals
provides fresh tc-99m daily for imaging.

18
Q

radiolabelling

A

process of attaching a radioisotope to a carrier molecule to create a radiopharmaceutical., e.g. Tc-99m binds to phosphates naturally accumulating in bones so this is ideal for bone scans.

radioactive compound -> linker -> targeting molecule -> target protein -> cancer cell

19
Q

what are the key functions of radiopharmaceutical preparation:

A

this takes place in a specialised hot lane, equipped with shielding and designed for safe handling and storage of radioactive materials.

key functions:

-radiopharmaceutical preparation
-quality control testing (radiochemical purity)
-dose measurement

20
Q

what are the essential tools used when preparing radiopharmaceutical d

A

-lead glass window: protects staff
-vial shelf and tongs to handle sources
-shielded containers and syringes: limits exposure when handling. also used for prep and administration of radiopharmaceuticals

21
Q

how is radiopharmaceutical dose calculated?

A

accurate dosing- calculated based on patients weight, height, medical needs and scan type.

22
Q

preparation of administration

A
  • safe transport and handling: using shielded containers to transport radiopharmaceutical

-administration to patient: injection or oral, depending on scan requirements

-imaging procedure: immediate or delayed imaging based on radiopharmaceutical and scan type.

23
Q

what does SPECT stand for?

A

single photon emission computed tomography

24
Q

what is the definition of spect

-single photon:
-emission imaging:
-computed:
tomography:

A

single photon: detects single gamma photons that are emitted from a. tracer in the body, unlike chest XRs which just pass through

emission imaging: detects radiation emitted from the body

computed: algorithms to reconstruct images using multiple angles and enhancing details

tomography: creates 3d cross sectional images to enable precise tracer localisation

25
Q

gamma camra: spect

A

imaging device used to detect gamma rays released by radiopharmaceuticals to create an image

26
Q

gamma camera head: spect

A

camera that rotates around the patient capturing multiple angles

27
Q

SPECT computer

A

processes signals to create 3d images of tracer distribution

28
Q

what is the order of components in spect

A

-patient
-gamma camera
-collimator
-scinitillator and pmt
-computer
-display

29
Q

what is a collimator in spect and what are thew 2 different types

A

-collimator made of gamma ray absorbing material e.g. lead. allows only gamma rays n the correct direction pass through and be included in the imaging process.

-multihople parallel collimator
-pinhole collimator

30
Q

what are the features of a multihole parallel collimator:

A

-widely used and accessible in clinics
-different options to choose from based on tracer energy and resolution needed
-its like changing lens on a camera
-stored nearby, easy to swap and change

31
Q

what are the features of a pinhole collimator:

A

-single aperture / pinhole
-allows you to focus on smaller/ specific areas e.g. thyroid
-works like a magnifying glass

32
Q

what is the purpose of scintillation and pmt

A

transform gamma radiation into a digital image

33
Q

outline the process of scintillation and pmt

A

scintillator- uses crystals (often sodium iodide) converts gamma rays into visible light

photomultiplier tubes- detects this visible light ad converts it into electrical signals

computer: detects electrical signals, processes and converts them to create digital images

34
Q

SPECT vs planar imaging

A

planar imaging: single 2d projection, gamma camera does not rotate
useful for quick assessments, but lacks depth information

types of planar imaging:
static: single image e.g. thyroid
dynamic: rapid frames to track changes overtime e.g renal studies
whole body: a single image of the entire body by moving camera e.g. bone scans

35
Q

what is SPECT/CT

A
  • hybrid imaging: combines sect for function and CT for structure, in one scan

-benefit: provides both anatomical and functional information

-clinical utility: enhances localisation of abnormalities

36
Q

what is PET?

A

-nuclear med technique- visualises cellular and molecular activity
uses radioactive tracers e.g fluorine18- emits positrons detectable by PET scanner
-highly sensitive for detecting disease activity in:

-oncology
-neurology
-cardiology

37
Q

mechanism of pet imaging

A

positron emission: tracer releases positron’s that interact with electrons in the body

annihilation event: results in two gamma was emitted 180 degrees apart

38
Q

PET detection system

A

no collimator needed: detect photons from annihilation events, improving sensitivity.

ring of detectors: 360 degree detector ring to capture paired gamma rays

coincidence detection: paired gamma rays are detected simultaneously to pinpoint annihilation point

LOR: path connecting two detectors receiving the paired photons, indicating A.E location.

39
Q

image formation in PET

A

data collection: thousands of LORs captured during the scan

image reconstruction: software uses LORs to create a 3d map of metabolic activity

result: final images help diagnose cancer, brain and heart disease

40
Q
A

Imaging science and technology (7 decks)

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