A proposal for a quality control protocol in breast CT with synchrotron radiation Cover

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A proposal for a quality control protocol in breast CT with synchrotron radiation

Radiology and Oncology

Volume 52 (2018): Issue 3 (September 2018)

By: Adriano Contillo, Anna Veronese, Luca Brombal, Sandro Donato, Luigi Rigon, Angelo Taibi, Giuliana Tromba, Renata Longo and Fulvia Arfelli

Open Access

|Mar 2018

Figures & Tables

(A) QC phantom fixed at the breast position on the patient support. The upper portion is uniformly filled with water, while the radiographic details are visible in the lower portion. (B) Arrangement of the details at the bottom of the QC phantom. The rods are made of polyethylene (PE), nylon, polyoxymethylene (POM), polytetrafluoroethylene (PTFE), and BR12, a plastic material mimicking the attenuation properties of breast tissue. The structure of the low contrast PMMA insert, exhibiting the five holes of varying diameter, is clearly perceivable.

Example of reconstructed water image (left panel) and detail image (right panel), acquired at 38 keV and high dose.

Examples of linear regressions, performed on high dose images acquired at 32, 35, 38 and 40 keV, from top left panel to bottom right panel. R2 coefficients, slopes and intercepts are given as well.

Noise measurement of the reconstructed attenuation coefficient for water_ Relative percentual results are given for μ coefficients, absolute results for the corresponding HU values

Energy (keV)	Dose	noise_μ (%)	noise_HU
32	high	4.4	60
	low	8.5	103
35	high	3.8	83
	low	7.3	114
38	high	3.7	66
	low	6.5	109
40	high	3.5	66
	low	6.2	111

Uniformity of reconstructed attenuation coefficient for water_ Relative percentual values are given for μ coefficients, absolute values for the corresponding HU deviations

Energy (keV)	Dose	uniformity_μ (%)	uniformity_HU
32	high	1.79	17
	low	3.19	32
35	high	1.45	12
	low	1.47	13
38	high	2.58	26
	low	1.35	13
40	high	2.54	24
	low	1.07	10

Low contrast measurements_ Relative percentual contrasts are given for μ coefficients, absolute contrasts for the corresponding Hounsfield unit (HU)

Energy (keV)	Detail (mm)	μ contrast (%)		HU contrast

		high dose	low dose	high dose	low dose
32	10	0.81	0.71	7	5
	8	0.96	0.87	9	7
	6	1.10	0.53	10	4
	4	1.08	1.12	10	10
	2	0.52	0.93	5	8
35	10	1.80	1.85	15	15
	8	1.68	1.73	14	14
	6	1.56	1.64	13	13
	4	1.21	0.87	10	8
	2	0.90	0.91	8	8
38	10	4.14	3.86	41	39
	8	3.99	3.41	40	34
	6	3.66	4.02	36	41
	4	3.91	3.45	39	35
	2	3.17	3.79	31	38
40	10	5.35	5.49	54	55
	8	5.09	5.43	52	55
	6	5.12	4.85	52	49
	4	5.31	3.41	54	34
	2	5.73	3.79	59	38

Parameters of the linear regressions between measured CT numbers and tabulated attenuation coefficients

Energy (keV)	Dose	R²	slope (cm^–1)	intercept (cm^–1)
32	high	0.9996	175 ± 4	0.019 ± 0.009
	low	0.9996	170 ± 4	0.025 ± 0.009
35	high	0.9997	176 ± 4	0.018 ± 0.008
	low	0.9996	173 ± 4	0.017 ± 0.009
38	high	0.9998	177 ± 3	0.016 ± 0.005
	low	0.9992	175 ± 3	0.013 ± 0.006
40	high	0.9992	174 ± 7	0.021 ± 0.012
	low	0.9991	172 ± 7	0.019 ± 0.012

Accuracies of reconstructed attenuation coefficients for the plastic materials and water, acquired at 38 keV and high dose_ Expected values, measured values and relative percentual differences are given for μ coefficients, absolute differences for the corresponding HU deviations

Material	expected μ (cm^–1)	measured μ (cm^–1)	accuracy_μ (%)	accuracy_HU
PE	0.216	0.221 ± 0.002	3.1 ± 1.3	24 ± 10
BR12	0.260	0.249 ± 0.004	4.0 ± 1.6	37 ± 14
Nylon	0.271	0.273 ± 0.003	0.9 ± 1.0	8 ± 9
PMMA	0.290	0.291 ± 0.003	0.4 ± 1.2	4 ± 12
POM	0.359	0.360 ± 0.003	0.2 ± 0.8	3 ± 11
PTFE	0.622	0.633 ± 0.003	0.1 ± 0.5	3 ± 11
Water	0.282	0.278 ± 0.003	1.5 ± 0.9	14 ± 9

DOI: https://doi.org/10.2478/raon-2018-0015 | Journal eISSN: 1581-3207 | Journal ISSN: 1318-2099

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Language: English

Page range: 329 - 336

Submitted on: Dec 4, 2017

Accepted on: Dec 12, 2017

Published on: Mar 24, 2018

Published by: Association of Radiology and Oncology

In partnership with: Paradigm Publishing Services

Publication frequency: 4 issues per year

Keywords:

quality control,

radiographic phantom,

synchrotron radiation

Related subjects:

Clinical medicine,

Internal medicine,

Haematology, oncology,

© 2018 Adriano Contillo, Anna Veronese, Luca Brombal, Sandro Donato, Luigi Rigon, Angelo Taibi, Giuliana Tromba, Renata Longo, Fulvia Arfelli, published by Association of Radiology and Oncology
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

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