Nuclear Med Revision

Question 1

What generator do they use?

Answer 1

Technician -99m

Question 2

What happens after delivery of T-99m?

Answer 2

Collect the technician generator from delivery bay
Measure the external dose rate - if it’s above limit may indicate damaging leakage
And delivery details on database. All radioactive deliveries must be recorded when they arrive.

Question 3

What is used for a constancy check on the radionuclide assay calibrator ?

Answer 3

Caesium -137 source

Question 4

What is used to sterilise the isolator?

Answer 4

Hydrogen peroxide gas

Question 5

How do they get the elute out from the generator?

Answer 5

An evacuated vial is placed onto the generator which draws saline through the ion exchange column. This creates a solution of of t-99m in the form of Pertechnetate anions

Question 6

What is the hottest radiation source on any given day and what is it used for?

Answer 6

The solution of pertechnetate anions
They are used to prepare different radiopharmaceuticals

Question 7

What is done at the start of sessions to monitor the environment?

Answer 7

Agar plates are opened in various locations

Question 8

What happens to the eluted T-99m ?

Answer 8

It’s measured and entered onto the data base along with the volume of the solution. The volume is controlled by the evacuated vial

This vial is put into a tungsten sheild

Question 9

What is the typical Monday eluted activity?

Answer 9

110 GBq

Question 10

How are the different radiopharmaceuticals formed?

Answer 10

They come in the form of cold kits to which the pertechnate is added.

The kit vial contains everything needed for the T-99m to be reduced from the pertechnetate to form an oxidation state to bind with the desired molecule

Question 11

What determines the volume of pertechnetate added to each cold kit?

Answer 11

The radioactive concentration of the pertechnetate

Question 12

How much radiation does their fingers receive in a session?

Answer 12

1mS

Question 13

What happens at the end of a session?

Answer 13

• plates are closed and prepared kits passed into the support room
• the kits must be checked by another staff member - product release
They check the appearance, radioactivity level and volume
Also the lot number matches

Question 14

What is the molybdenum breach through test?

Answer 14

The first elution is checked for molybdenum-99 breakthrough.
To measure this the elute is put into a lead pot. This completely attenuates the T-99m gamma radiation but will allow a higher energy game rays form Molybdenum to pass through

Question 15

Why is it important that there is no M-99 in the kit vial?

Answer 15

Excess M-99 in the kit will affect the chemistry of the labelling
As it has a 1/2 life of 2.7 days - it will give unnecessary radiation dose to the patient well beyond the scan time

Question 16

What is the Aluminium break through test?

Answer 16

The first elute is also checked for Aluminium breakthrough.
The elute is spotted onto an indicator paper alongside an aluminium, standard solution. The spot turns pink in the presence of aluminium ions.
The eluate passes the test if there’s no pink colour or the intensity is less than that standard .

Question 17

Why is it important that there is no aluminium breakthrough?

Answer 17

Aluminium ions in the kit file will affect labelling chemistry and cause particulate injections to clump together which will impair the in vivo behaviour.

Question 18

What is the threshold for the accepted radioactivity?

Answer 18

Within 10%

Question 19

How are QC checks completed on the gamma camera?

Answer 19

Uniformity test - checks the camera is imaging a uniform source of radioactivity as a uniform image

A flat source of Colbalt-57 is placed on the camera head

Difference betweeen hottest and coldest should be no more than 3%

Question 20

What is the definition of Eluate?

Answer 20

Neat pertechnetate taken directly from the elution which is used to create Technegas for lung ventilation imaging

Question 21

What is Technescan HDP?

Answer 21

HDP (hydroxydiphosphonate) a bone scanning agent

Question 22

What is nanoscan?

Answer 22

Nanocolloid used to image lymphatic flow

Question 23

What is pulmonic (MAA)?

Answer 23

MAA ( macroaggregrated albumin) a particle suspension used to image blood flow in the lung

Question 24

What is involved in a sentinel node scan?

Answer 24

They are injected with 10MBq of T-99m nano scan intradermally in the same quadrant as their breast tumour

They are then imaged to track the lymphatic drainage of the injection to the sentinel, lymph node

The scans are carefully coordinated with theatre .

Question 25

How is the sentinel node scan used in theatre?

Answer 25

The images and the use of a radiation probe guides the surgeon to which node to be removed The note is examined for signs of metastatic cancer cells If the node is clear, and there’s no need to remove any further notes The patient can be spared, impaired lymphatic drainage and swollen arm .

Question 26

What is used for nuclear medicine bone scans for breast cancer?

Answer 26

T-99m

Question 27

What to do in the event of a spill of radioactive substance?

Answer 27

~ after a spill take care that nobody steps on the floor where the spill occurred ~ clean up starts by absorbing the spill onto a dry wipe that’s placed into a shielded waste bin ~ The area is monitored to measure contamination in Bq per cm^2 ~ after clean up with detergent and dry wipes the level is above 30 bqcm^-2 Which is above the limit for T-99m This amount is not an exposure hazard but a contamination hazard so its covered with waterproof plastic and left to decay

Question 28

What must patients have prior to a v/Q scan?

Answer 28

A CXR to rule out gross changes that explain symptoms

Question 29

What happens to produce the gas’s for the ventilation part of the V/Q scan?

Answer 29

The technegas generator is prepared 0.14 ml of perechenetate solution is added to the carbon crucible This is then headed to boil off the water solvent - simmering Just before inhalation - the gas is created by heating the crucible to 2750 degrees c in an inert argon atmosphere to generate the T-99m labelled carbon particles

Question 30

During the Ventilation part of the V/Q scan how does the patient inhale the gas?

Answer 30

The patient inhales through a one- way filtered mouthpiece with a nose clip on. They have a chance to practice before the scan The patient will inhale the gas over a camera which monitors the lung activity until the correct count rate is reached They are then scanned using SPECT to get 3D representation of the lungs

Question 31

What happens during the perfusion part of a V/Q scan?

Answer 31

Th pt is given IV injection of 100mMBq of T-99m MAA This is also given with the person over a camera to ensure the activity is at least 4x that of the technegas They then are scanned using SPECT to create a 3 D representation of blood flow in the lungs

Question 32

What SPECT images are acquired?

Answer 32

At derriford - head/thorax , thorax/abdo, abdo/pelvis Most of the UK - Anterior and posterior planar whole body scan

Question 33

What are the +/- of spect?

Answer 33

It offers greater sensitivity and specificity It take twice as long

Question 34

What is the level considered safe for T-99m

Answer 34

30 Bq per cm squared