3D printed phantom with 12 000 submillimeter lesions to improve efficiency in CT detectability assessment
Fuente:
Wiley Open Access
Saved in:
| Main Authors: | , , , , , , , , , , |
|---|---|
| Format: | Artículo Open Access |
| Published: |
Wiley
2024
|
| Subjects: | |
| Online Access: | |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1867010971454668800 |
|---|---|
| author | Picha Shunhavanich Kai Mei Nadav Shapira Joseph Webster Stayman Cynthia H. McCollough Grace Gang Shuai Leng Michael Geagan Lifeng Yu Peter B. Noël Scott S. Hsieh |
| author_facet | Picha Shunhavanich Kai Mei Nadav Shapira Joseph Webster Stayman Cynthia H. McCollough Grace Gang Shuai Leng Michael Geagan Lifeng Yu Peter B. Noël Scott S. Hsieh Picha Shunhavanich Kai Mei Nadav Shapira Joseph Webster Stayman Cynthia H. McCollough Grace Gang Shuai Leng Michael Geagan Lifeng Yu Peter B. Noël Scott S. Hsieh |
| collection | Wiley Open Access |
| contents | 3D printed phantom with 12 000 submillimeter lesions to improve efficiency in CT detectability assessment Picha Shunhavanich Kai Mei Nadav Shapira Joseph Webster Stayman Cynthia H. McCollough Grace Gang Shuai Leng Michael Geagan Lifeng Yu Peter B. Noël Scott S. Hsieh Medical Physics AbstractBackgroundThe detectability performance of a CT scanner is difficult to precisely quantify when nonlinearities are present in reconstruction. An efficient detectability assessment method that is sensitive to small effects of dose and scanner settings is desirable. We previously proposed a method using a search challenge instrument: a phantom is embedded with hundreds of lesions at random locations, and a model observer is used to detect lesions. Preliminary tests in simulation and a prototype showed promising results.PurposeIn this work, we fabricated a full‐size search challenge phantom with design updates, including changes to lesion size, contrast, and number, and studied our implementation by comparing the lesion detectability from a nonprewhitening (NPW) model observer between different reconstructions at different exposure levels, and by estimating the instrument sensitivity to detect changes in dose.MethodsDesigned to fit into QRM anthropomorphic phantoms, our search challenge phantom is a cylindrical insert 10 cm wide and 4 cm thick, embedded with 12 000 lesions (nominal width of 0.6 mm, height of 0.8 mm, and contrast of −350 HU), and was fabricated using PixelPrint, a 3D printing technique. The insert was scanned alone at a high dose to assess printing accuracy. To evaluate lesion detectability, the insert was placed in a QRM thorax phantom and scanned from 50 to 625 mAs with increments of 25 mAs, once per exposure level, and the average of all exposure levels was used as high‐dose reference. Scans were reconstructed with three different settings: filtered‐backprojection (FBP) with Br40 and Br59, and Sinogram Affirmed Iterative Reconstruction (SAFIRE) with strength level 5 and Br59 kernel. An NPW model observer was used to search for lesions, and detection performance of different settings were compared using area under the exponential transform of free response ROC curve (AUC). Using propagation of uncertainty, the sensitivity to changes in dose was estimated by the percent change in exposure due to one standard deviation of AUC, measured from 5 repeat scans at 100, 200, 300, and 400 mAs.ResultsThe printed insert lesions had an average position error of 0.20 mm compared to printing reference. As the exposure level increases from 50 mAs to 625 mAs, the lesion detectability AUCs increase from 0.38 to 0.92, 0.42 to 0.98, and 0.41 to 0.97 for FBP Br40, FBP Br59, and SAFIRE Br59, respectively, with a lower rate of increase at higher exposure level. FBP Br59 performed best with AUC 0.01 higher than SAFIRE Br59 on average and 0.07 higher than FBP Br40 (all P < 0.001). The standard deviation of AUC was less than 0.006, and the sensitivity to detect changes in mAs was within 2% for FBP Br59.ConclusionsOur 3D‐printed search challenge phantom with 12 000 submillimeter lesions, together with an NPW model observer, provide an efficient CT detectability assessment method that is sensitive to subtle effects in reconstruction and is sensitive to small changes in dose. 10.1002/mp.17064 http://onlinelibrary.wiley.com/termsAndConditions#vor |
| doi_str_mv | 10.1002/mp.17064 |
| format | Artículo Open Access |
| id | wiley_oa_10_1002_mp_17064 |
| institution | Wiley Open Access |
| license_str_mv | http://onlinelibrary.wiley.com/termsAndConditions#vor |
| publishDate | 2024 |
| publisher | Wiley |
| record_format | wiley_oa |
| spellingShingle | 3D printed phantom with 12 000 submillimeter lesions to improve efficiency in CT detectability assessment Picha Shunhavanich Kai Mei Nadav Shapira Joseph Webster Stayman Cynthia H. McCollough Grace Gang Shuai Leng Michael Geagan Lifeng Yu Peter B. Noël Scott S. Hsieh Medical Physics 3D printed phantom with 12 000 submillimeter lesions to improve efficiency in CT detectability assessment Picha Shunhavanich Kai Mei Nadav Shapira Joseph Webster Stayman Cynthia H. McCollough Grace Gang Shuai Leng Michael Geagan Lifeng Yu Peter B. Noël Scott S. Hsieh Medical Physics AbstractBackgroundThe detectability performance of a CT scanner is difficult to precisely quantify when nonlinearities are present in reconstruction. An efficient detectability assessment method that is sensitive to small effects of dose and scanner settings is desirable. We previously proposed a method using a search challenge instrument: a phantom is embedded with hundreds of lesions at random locations, and a model observer is used to detect lesions. Preliminary tests in simulation and a prototype showed promising results.PurposeIn this work, we fabricated a full‐size search challenge phantom with design updates, including changes to lesion size, contrast, and number, and studied our implementation by comparing the lesion detectability from a nonprewhitening (NPW) model observer between different reconstructions at different exposure levels, and by estimating the instrument sensitivity to detect changes in dose.MethodsDesigned to fit into QRM anthropomorphic phantoms, our search challenge phantom is a cylindrical insert 10 cm wide and 4 cm thick, embedded with 12 000 lesions (nominal width of 0.6 mm, height of 0.8 mm, and contrast of −350 HU), and was fabricated using PixelPrint, a 3D printing technique. The insert was scanned alone at a high dose to assess printing accuracy. To evaluate lesion detectability, the insert was placed in a QRM thorax phantom and scanned from 50 to 625 mAs with increments of 25 mAs, once per exposure level, and the average of all exposure levels was used as high‐dose reference. Scans were reconstructed with three different settings: filtered‐backprojection (FBP) with Br40 and Br59, and Sinogram Affirmed Iterative Reconstruction (SAFIRE) with strength level 5 and Br59 kernel. An NPW model observer was used to search for lesions, and detection performance of different settings were compared using area under the exponential transform of free response ROC curve (AUC). Using propagation of uncertainty, the sensitivity to changes in dose was estimated by the percent change in exposure due to one standard deviation of AUC, measured from 5 repeat scans at 100, 200, 300, and 400 mAs.ResultsThe printed insert lesions had an average position error of 0.20 mm compared to printing reference. As the exposure level increases from 50 mAs to 625 mAs, the lesion detectability AUCs increase from 0.38 to 0.92, 0.42 to 0.98, and 0.41 to 0.97 for FBP Br40, FBP Br59, and SAFIRE Br59, respectively, with a lower rate of increase at higher exposure level. FBP Br59 performed best with AUC 0.01 higher than SAFIRE Br59 on average and 0.07 higher than FBP Br40 (all P < 0.001). The standard deviation of AUC was less than 0.006, and the sensitivity to detect changes in mAs was within 2% for FBP Br59.ConclusionsOur 3D‐printed search challenge phantom with 12 000 submillimeter lesions, together with an NPW model observer, provide an efficient CT detectability assessment method that is sensitive to subtle effects in reconstruction and is sensitive to small changes in dose. 10.1002/mp.17064 http://onlinelibrary.wiley.com/termsAndConditions#vor |
| title | 3D printed phantom with 12 000 submillimeter lesions to improve efficiency in CT detectability assessment |
| topic | Medical Physics |
| url | https://aapm.onlinelibrary.wiley.com/doi/10.1002/mp.17064 |