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273. Ottimizzazione dei protocolli in angiografia
230
Abstracts / Physica Medica 56 (2018) 133–278
ðBG ROIÞ SNR ¼ qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 2 2
ðSTDBG þSTDROI Þ 2
where: BG and Roi are the mean value of the pixel in the region of interest located in the background and in the second circle respectively, and STDBG and STDROI are the relative standard deviation, and finally the figure of merit (FOM): FOM ¼
SNR2 ED
where ED stands for entrance dose [1]. Results. we uzed this method to evaluate two different angiogranphic systems: A and B. In the first one we compared different automatic exposure preferences both for fluoroscopy and fluorography, in the second one we compared low dose protocols to normal dose ones both in cardiac imaging and in DSA body. Conclusions. For A: in fluoroscopy RDL + mode is the best in terms of SNR and FOM respect to RDLstd and IQstd; in fluorography there is only the IQstd mode, but the low detail setting has a FOM that is comparable to normal detail setting, at half the dose. For B: Card low dose protocols have the best FOM values, especially using a FOV of 32. In the case of DSAbody low dose the dose more then half the dose obtained with the standard protocol, but the SNR is not degraded and the FOM is even higher.
evaluated for two different DBT devices at seven different values of AGD, obtained manually setting the tube current time product. Results. Each DBT device showed a characteristic value of DBTI. These values were constant as the tube current time product changes, with a standard deviation of 2% and 6% for the two devices. Conclusions. Independence of DBTI from exposure parameters could make it a good FoM to benchmark DBT devices. Compared to CT, DBT have less clinical questions, so a single score could provide a reliable estimation of the goodness of the DBT device.
References 1. Vano E. Dynamic flat panel detector versus image intensifier in cardiac imaging: dose and image quality. Phys Med Biol 2005;50:5731–42.
References https://doi.org/10.1016/j.ejmp.2018.04.283
1. Strocchi S, Vite C, Novario R, Cacciatori M, Frigerio G, Conte L. Computed tomography quality indexes: evaluation experience. Proc. SPIE 2009;7258:1–8.
274. Multi hospital experiences of Radiation Dose Index Monitoring (RDMI) in mammography S. Pini a, S. Mazzocchi a, L. Noferini b, E. Rigacci a, G. Cicoria a, G. Zatelli a
https://doi.org/10.1016/j.ejmp.2018.04.282
a
273. Ottimizzazione dei protocolli in angiografia E. Lorenzini a, F. Daumiller b, D. Fosi b, A. Tofani a a b
b
USL Toscana Centro, Medical Physics Department, Firenze, Italy USL Toscana Sud-Est, Medical Physics Department, Arezzo, Italy
Purpose. Aim of this work was to use the dose index information from 5 mammography units within USL Toscana Centro, FirenzeEmpoli area, analysing and comparing the compression force data and the AGD trend with the thickness of the compressed breast. Methods. The RDMI data from Siemens Mammomat Inspiration mammography units were analysed by exploiting the information gathered in a local LOG file that records all the exposure parameters of each single shot. Data in the file are extracted in a spreadsheet tool. All the devices have the same kV-breast thickness compensation curve and work in AEC mode with a W/Rh combination. For the analysis, we focused on data for the year 2015–2016 covering about 40,000 patients for a total of over 169,200 projections. Data are filtered eliminating quality test and manual exposures, breast implants and surgical pieces.
U.O. Fisica Sanitaria, Azienda USL Toscana Nord Ovest, Carrara, Italy U.O. Radiodiagnostica, Azienda USL Toscana Nord Ovest, Massa, Italy
Purpose. In reducing dose in angiography, one of the chance one has is knowing the impact of each parameter or operational mode within a protocol in order to make the right balance between dose and image quality. Methods. PMMA plates of dimensions 25 cm 25 cm, and different thicknesses in order to get a total thickness of 20 cm. At the middle, we put a Leeds TOR 18-FG test object, positioned at the isocenter of the machine. A ionization camera (RadCal) in contact with the PMMA plates was used to measure entrance air dose simultaneously with image acquisition. We evaluated: high contrast spatial resolution (bar-patterns), SNR in the second circle calculated as:
Equivalent breast thickness
Median AGD value (1rd and 3rd quartile) [mGy]
[mm]
Unit 1
Unit 2
Unit 3
Unit 4
Unit 5
acceptable level [mGy]
achievable level [mGy]
32 45 53 60 75
1.2 1.5 1.6 1.8 2.4
1.0 1.2 1.4 1.5 2.0
1.0 1.3 1.4 1.5 2.0
1.2 1.4 1.6 1.7 2.1
1.1 1.2 1.4 1.6 1.8
1.5 2.0 2.5 3.0 4.5
1.0 1.6 2.0 2.4 3.6
(1.1–1.5) (1.2–1-8) (1.4–2.0) (1.5–2.2) (2.1–2.9)
(0.9–1.2) (1.0–1.5) (1.2–1.7) (1.3–1.9) (1.8–2.5)
(0.9–1.2) (1.0–1.5) (1.2–1.8) (1.3–1.9) (1.7–2.4)
Maximum AGD EUREF Guidelines
(1.0–1.4) (1.2–1.8) (1.3–2.0) (1.9–2.5) (1.9–2.4)
(1.0–1.2) (1.0–1.5) (1.2–1.7) (1.3–1.9) (1.6–2.2)
Abstracts / Physica Medica 56 (2018) 133–278
ðBG ROIÞ SNR ¼ qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 2 2
ðSTDBG þSTDROI Þ 2
where: BG and Roi are the mean value of the pixel in the region of interest located in the background and in the second circle respectively, and STDBG and STDROI are the relative standard deviation, and finally the figure of merit (FOM): FOM ¼
SNR2 ED
where ED stands for entrance dose [1]. Results. we uzed this method to evaluate two different angiogranphic systems: A and B. In the first one we compared different automatic exposure preferences both for fluoroscopy and fluorography, in the second one we compared low dose protocols to normal dose ones both in cardiac imaging and in DSA body. Conclusions. For A: in fluoroscopy RDL + mode is the best in terms of SNR and FOM respect to RDLstd and IQstd; in fluorography there is only the IQstd mode, but the low detail setting has a FOM that is comparable to normal detail setting, at half the dose. For B: Card low dose protocols have the best FOM values, especially using a FOV of 32. In the case of DSAbody low dose the dose more then half the dose obtained with the standard protocol, but the SNR is not degraded and the FOM is even higher.
evaluated for two different DBT devices at seven different values of AGD, obtained manually setting the tube current time product. Results. Each DBT device showed a characteristic value of DBTI. These values were constant as the tube current time product changes, with a standard deviation of 2% and 6% for the two devices. Conclusions. Independence of DBTI from exposure parameters could make it a good FoM to benchmark DBT devices. Compared to CT, DBT have less clinical questions, so a single score could provide a reliable estimation of the goodness of the DBT device.
References 1. Vano E. Dynamic flat panel detector versus image intensifier in cardiac imaging: dose and image quality. Phys Med Biol 2005;50:5731–42.
References https://doi.org/10.1016/j.ejmp.2018.04.283
1. Strocchi S, Vite C, Novario R, Cacciatori M, Frigerio G, Conte L. Computed tomography quality indexes: evaluation experience. Proc. SPIE 2009;7258:1–8.
274. Multi hospital experiences of Radiation Dose Index Monitoring (RDMI) in mammography S. Pini a, S. Mazzocchi a, L. Noferini b, E. Rigacci a, G. Cicoria a, G. Zatelli a
https://doi.org/10.1016/j.ejmp.2018.04.282
a
273. Ottimizzazione dei protocolli in angiografia E. Lorenzini a, F. Daumiller b, D. Fosi b, A. Tofani a a b
b
USL Toscana Centro, Medical Physics Department, Firenze, Italy USL Toscana Sud-Est, Medical Physics Department, Arezzo, Italy
Purpose. Aim of this work was to use the dose index information from 5 mammography units within USL Toscana Centro, FirenzeEmpoli area, analysing and comparing the compression force data and the AGD trend with the thickness of the compressed breast. Methods. The RDMI data from Siemens Mammomat Inspiration mammography units were analysed by exploiting the information gathered in a local LOG file that records all the exposure parameters of each single shot. Data in the file are extracted in a spreadsheet tool. All the devices have the same kV-breast thickness compensation curve and work in AEC mode with a W/Rh combination. For the analysis, we focused on data for the year 2015–2016 covering about 40,000 patients for a total of over 169,200 projections. Data are filtered eliminating quality test and manual exposures, breast implants and surgical pieces.
U.O. Fisica Sanitaria, Azienda USL Toscana Nord Ovest, Carrara, Italy U.O. Radiodiagnostica, Azienda USL Toscana Nord Ovest, Massa, Italy
Purpose. In reducing dose in angiography, one of the chance one has is knowing the impact of each parameter or operational mode within a protocol in order to make the right balance between dose and image quality. Methods. PMMA plates of dimensions 25 cm 25 cm, and different thicknesses in order to get a total thickness of 20 cm. At the middle, we put a Leeds TOR 18-FG test object, positioned at the isocenter of the machine. A ionization camera (RadCal) in contact with the PMMA plates was used to measure entrance air dose simultaneously with image acquisition. We evaluated: high contrast spatial resolution (bar-patterns), SNR in the second circle calculated as:
Equivalent breast thickness
Median AGD value (1rd and 3rd quartile) [mGy]
[mm]
Unit 1
Unit 2
Unit 3
Unit 4
Unit 5
acceptable level [mGy]
achievable level [mGy]
32 45 53 60 75
1.2 1.5 1.6 1.8 2.4
1.0 1.2 1.4 1.5 2.0
1.0 1.3 1.4 1.5 2.0
1.2 1.4 1.6 1.7 2.1
1.1 1.2 1.4 1.6 1.8
1.5 2.0 2.5 3.0 4.5
1.0 1.6 2.0 2.4 3.6
(1.1–1.5) (1.2–1-8) (1.4–2.0) (1.5–2.2) (2.1–2.9)
(0.9–1.2) (1.0–1.5) (1.2–1.7) (1.3–1.9) (1.8–2.5)
(0.9–1.2) (1.0–1.5) (1.2–1.8) (1.3–1.9) (1.7–2.4)
Maximum AGD EUREF Guidelines
(1.0–1.4) (1.2–1.8) (1.3–2.0) (1.9–2.5) (1.9–2.4)
(1.0–1.2) (1.0–1.5) (1.2–1.7) (1.3–1.9) (1.6–2.2)