:: quiz - additional questions
You may have noticed that the quiz questions jumped from Q12 to Q16 overnight. There were 3 extra questions of interest that were left for the student.
I have put them here so that you can have a go at them yourself. They are quite interesting to do, honestly - so have a go. I will put my answers up on the site after Easter, so you have the long weekend to contemplate them. Enjoy
round 5 questions
Q13: How big is CT data?
How many GB of data can one scanning room in a month? (Round up the answer to the nearest '10')
You can make the following assumptions:
- Scanner producing an average of 250 images per study
- 5 patients (or studies) per hour
- 8 working hours a day
- 20 scanning days per month
- Image matrix: 512 x 512
- Value range: -1000 to + 3000 HU
- the file only stores enough bits for the 'bit depth' of the value range (that is, 12 bits)
- Only consider image data : ignore any file header and non-image information
- The data / files are uncompressed
Q14:Pitch in MSCT
A scanner acquiring four slices of 5 mm in helical mode, rotation time 0.75 s, table feed is 40 mm per second
- What is pitchx?
- What is pitchd ?
- How are the two related ?
Q15: Isotropic imaging
What slice width would be needed to produce isotropic images on a 512 x 512 matrix when the field of view is a) 250 mm and b) 500 mm?
In the latter case (500 mm RFOV), what would be the effect on the voxel of changing the reconstruction matrix to 768 x 768 ?
Of interest: if you were to adjust the slice thicknesses as above, what would happen in terms of the image noise ?
Click here for the answers