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slide1

ABSTRACT

Earlier this year Lakes Radiology was approached by Scion in Rotorua about using MRI and CT as part of a research project to assess the amount of water in wood. This paper reviews the process of setting up scan protocols, problems encountered and how they were solved, the significance of using MRI and CT, how the information obtained from the scans has assisted the researchers and what has been learned from this experience.

Fri 30th Aug 2013

Session 2 / Talk 3

11:22 – 11:33

HEAPHY 1 & 2

DIAGNOSTIC

Delia DEPHOFF

delia dephoff nzimrt conference 2013 hamilton
Delia Dephoff

NZIMRT Conference

2013 Hamilton

Using MRI and CT for scientific research – one MRT’s experience

As wet as four short planks

introduction

Background – who, what and why

Trials scans – setting things up

Research series – modifications along the way

Review – was it of value, and what I learned

Introduction
background who

Scion - Crown Research Institute dedicated to improving the international competitiveness of the New Zealand forest industry and building a stronger biobased economy.

Lakes Radiology - TRG Group – private medical imaging facility

Background - Who
slide5
Who

Slobodan the researcher

Delia the MRT

background discussion

Research on different wood drying processes

Why CT and MRI?

Non-destructive measurement of the moisture content of wood

What was different about this research?

1st time MR &CT used in same research

Background - discussion
background wood drying processes

Kiln dried wood (KD) – dries from the outside –resulting in cracking and warping

Dewatered wood (DW) – basically replaces water in wood with alcohol which is then extracted – wood dried quickly from the inside – minimise cracking and warping

Background - Wood drying processes
trial scans aim

To scan the wood to set scan parameters

To assess the data obtained and determine if the information would be useful for the research.

Trial Scans - Aim
the wood

PinusRadiata

100x50x600mm (2 foot 4x2)

The Wood
ct protocol

Based on extremity scan

Dropped to 80 kVp , eff 50mAs (32mAs)

Kernals – soft tissue (B41s) and Bone (B70s)

2mm slices and 0.75mm slices

Pitch 1.5

16x0.6m

Rotation time 1.5

Scan time 44.75s

CTD I Vol 1.43 mGy

CT protocol
trial scans ct issues

Images - Streaking artefact

?partial volume averaging

beam hardening

(Seeram, 2001)

Trial scans - CT - issues
trial scans mri issues

Length of wood vs FOV

Coils – spine coil and body matrix x 2

T1, PD, T2

Scanned a small block

5mm slices

Trial Scans - MRI - Issues
trial scans data

HUGE amount of data esp CT

Raw data – 2.5GB

Siemens technical help

Transferred data onto external hard drive

Trial Scans - Data
research series1

1st series – comparing kiln dried wood to de-watered wood

2nd series – de-watered wood, Green, 3xDW, 5xDW, 10xDW

3rd series – unexpected results therefore re-scan after 2xDW and 10xDW

Research Series
1 st series mri issues

Wanted whole length of wood scanned

Change parameters slightly

Scan in two blocks, with overlap

Slice 7mm

Scan time approx 5mins each - 6 scans – 30mins to scan each set of wood

1st Series - MRI - Issues
what do you do while scans are running

Talked and asked questions – resulted in some minor adjustments to the research

  • Wood processing
  • Basics of CT and MRI
    • Hounsfield Units
    • Kernals – AKA Convolution filters
    • B41s high frequency filter
    • B70s low frequency filter (Bushong2000)
    • B90s
What do you do while scans are running?
3 rd series

Results from 2nd series not quite as expected

Water content was down after 3 DW, but increased after 5 DW, down again after 10DW

2x DW to 10 x DW

Use alcohol as a reference

3rd Series
3 rd series mri1
3rd Series - MRI

T1

PD

T2

Green

2DW

10DW

was the scan data of helpful for their research

Yes and no

PD most useful MR scan

Amount of data, especially CT – time to analyse

Unexpected results

Was the scan data of helpful for their research?
what have i learned

To get everything set on the trial scans, minimise errors, variables – check all parameters match

If there are options (e.g. kernals) give all for analysis

Revise CT and MR physics

What have I learned?
what have i learned1

Water content of wood, free water and bound water

Wood drying processes – kiln, dewatering and oven drying

You cannot measure the water content of a wet piece of wood, but you can measure how much water it used to contain once it has been dried.

What have I learned?
thanks to

Scion Research

Lakes Radiology – TRG Group

Slobodan Bradic

Thanks to
references

Bushong, S.C. (2000) Computed tomography. McGraw-Hill: New York

Seeram, E. (2001) Computed tomography. Physical principles, clinical applications, and quality control (2nded). Saunders: Philadelphia

References