Bär, Esther;
Volz, Lennart;
Collins‐Fekete, Charles‐Antoine;
Brons, Stephan;
Runz, Armin;
Schulte, Reinhard Wilhelm;
Seco, Joao;
(2022)
Experimental comparison of photon versus particle computed tomography to predict tissue relative stopping powers.
Medical Physics
, 49
(1)
pp. 474-487.
10.1002/mp.15283.
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Abstract
Purpose: Measurements comparing relative stopping power (RSP) accuracy of state-of-the-art systems representing single-energy and dual-energy computed tomography (SECT/DECT) with proton CT (pCT) and helium CT (HeCT) in biological tissue samples. Methods: We used 16 porcine and bovine samples of various tissue types and water, covering an RSP range from 0.90urn:x-wiley:00942405:media:mp15283:mp15283-math-00010.06 to 1.78 urn:x-wiley:00942405:media:mp15283:mp15283-math-00020.05. Samples were packed and sealed into 3D-printed cylinders (urn:x-wiley:00942405:media:mp15283:mp15283-math-0003 cm, urn:x-wiley:00942405:media:mp15283:mp15283-math-0004 cm) and inserted into an in-house designed cylindrical polymethyl methacrylate (PMMA) phantom (urn:x-wiley:00942405:media:mp15283:mp15283-math-0005 cm, urn:x-wiley:00942405:media:mp15283:mp15283-math-0006 cm). We scanned the phantom in a commercial SECT and DECT (120 kV; 100 and 140 kV/Sn (tin-filtered)); and acquired pCT and HeCT (urn:x-wiley:00942405:media:mp15283:mp15283-math-0007 MeV/u, 2urn:x-wiley:00942405:media:mp15283:mp15283-math-0008 steps, urn:x-wiley:00942405:media:mp15283:mp15283-math-0009 (p)/urn:x-wiley:00942405:media:mp15283:mp15283-math-0010 (He) particles/projection) with a particle imaging prototype. RSP maps were calculated from SECT/DECT using stoichiometric methods and from pCT/HeCT using the DROP-TVS algorithm. We estimated the average RSP of each tissue per modality in cylindrical volumes of interest and compared it to ground truth RSP taken from peak-detection measurements. Results: Throughout all samples, we observe the following root-mean-squared RSP prediction errors urn:x-wiley:00942405:media:mp15283:mp15283-math-0011 combined uncertainty from reference measurement and imaging: SECT 3.10urn:x-wiley:00942405:media:mp15283:mp15283-math-00122.88%, DECT 0.75urn:x-wiley:00942405:media:mp15283:mp15283-math-00132.80%, pCT 1.19urn:x-wiley:00942405:media:mp15283:mp15283-math-0014 2.81%, and HeCT 0.78urn:x-wiley:00942405:media:mp15283:mp15283-math-00152.81%. The largest mean errors urn:x-wiley:00942405:media:mp15283:mp15283-math-0016 combined uncertainty per modality are SECT 8.22 urn:x-wiley:00942405:media:mp15283:mp15283-math-00172.79% in cortical bone, DECT 1.74urn:x-wiley:00942405:media:mp15283:mp15283-math-00182.00% in back fat, pCT 1.80 urn:x-wiley:00942405:media:mp15283:mp15283-math-00194.27% in bone marrow, and HeCT 1.37urn:x-wiley:00942405:media:mp15283:mp15283-math-00204.25% in bone marrow. Ring artifacts were observed in both pCT and HeCT reconstructions, imposing a systematic shift to predicted RSPs. Conclusion: Comparing state-of-the-art SECT/DECT technology and a pCT/HeCT prototype, DECT provided the most accurate RSP prediction, closely followed by particle imaging. The novel modalities pCT and HeCT have the potential to further improve on RSP accuracies with work focusing on the origin and correction of ring artifacts. Future work will study accuracy of proton treatment plans using RSP maps from investigated imaging modalities.
| Type: | Article |
|---|---|
| Title: | Experimental comparison of photon versus particle computed tomography to predict tissue relative stopping powers |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1002/mp.15283 |
| Publisher version: | https://doi.org/10.1002/mp.15283 |
| Language: | English |
| Additional information: | This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. See: http://creativecommons.org/licenses/by/4.0/ |
| Keywords: | Dual-energy computed tomography, particle computed tomography, proton stopping power |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Med Phys and Biomedical Eng |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10160587 |
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