TU-C-213CD-05: 4D-CT Simulation Using Individually Optimized Contrast Enhancement (CE): A Phantom Study

Objective: Different CT scanners have different X-ray spectra and photon energies indicating that contrast enhancement vary among scanners. However, this issue has not been fully validated; therefore, we performed phantom and clinical studies to assess this difference. Methods: Two scanners were used: scanner-A and scanner-B. In the phantom study, we compared the contrast enhancement between the scanners at tube voltage peaks of 80, 100 and 120 kVp. Then, we calculated the effective energies of the two CT scanners. In the clinical study, 40 patients underwent abdominal scanning with scanner-A and another 40 patients with scanner-B, with each group using the same scanning protocol. The contrast enhancement of abdominal organs was assessed quantitatively (based on the absolute difference between the attenuation of unenhanced scans and contrast-enhanced scans) and qualitatively. A two-tailed independent Student's t-test and or the Mann–Whitney U test were used to compare the discrepancies. Results: In the phantom study, contrast enhancement for scanner-B was 36.9, 32.6 and 30.8% higher than that for scanner-A at 80, 100 and 120 kVp, respectively. The effective energies were higher for scanner-A than for scanner-B. In the quantitative analysis for the clinical study, scanner-B yielded significantly better contrast enhancement of the hepatic parenchyma, pancreas, kidney, portal vein and inferior vena cava compared with that of scanner-A. The mean visual scores for contrast enhancement were also significantly higher on images obtained by scanner-B than those by scanner-A. Conclusion: There were significant differences in contrast enhancement of the abdominal organs between the compared CT scanners from two different vendors even at the same scanning and contrast parameters. Advances in knowledge: Awareness of the impact of different X-ray energies on the resultant attenuation of contrast material is important when interpreting clinical CT images.

Download Full-text

SU-F-J-117: Impact of Motion Artifacts On Image Quality and Accuracy of Tumor Motion Reconstruction in 4D CT-On-Rails and MV-CBCT Scans: A Phantom Study

Medical Physics ◽

10.1118/1.4956025 ◽

2016 ◽

Vol 43 (6Part10) ◽

pp. 3433-3434

Author(s):

T Lin ◽

C Ma

Keyword(s):

Image Quality ◽

Motion Artifacts ◽

Phantom Study ◽

Tumor Motion ◽

Motion Reconstruction ◽

4D Ct

Download Full-text

Dosimetric Effects of Low Dose 4D CT Using a Commercial Iterative Reconstruction on Dose Calculation in Radiation Treatment Planning: A Phantom Study

Progress in Medical Physics ◽

10.14316/pmp.2017.28.1.27 ◽

2017 ◽

Vol 28 (1) ◽

pp. 27

Author(s):

Hee Jung Kim ◽

Sung Yong Park ◽

Young Hee Park ◽

Ah Ram Chang

Keyword(s):

Treatment Planning ◽

Iterative Reconstruction ◽

Low Dose ◽

Radiation Treatment ◽

Dose Calculation ◽

Phantom Study ◽

Radiation Treatment Planning ◽

4D Ct

Download Full-text

The impact of four dimensions CT simulation on planning target volume in radiotherapy for primary lung cancer.

Journal of Clinical Oncology ◽

10.1200/jco.2017.35.15_suppl.e20091 ◽

2017 ◽

Vol 35 (15_suppl) ◽

pp. e20091-e20091

Author(s):

Fawzi Jamil Abuhijla ◽

Lubna Abdelrahman Hammoudeh ◽

Ramiz Ahmad Abu-Hijlih ◽

Jamal Khader

Keyword(s):

Lung Cancer ◽

Planning Target Volume ◽

Tumor Volume ◽

Multivariable Analysis ◽

Primary Lung Cancer ◽

Free Breathing ◽

Target Volume ◽

4D Ct ◽

Ct Simulation ◽

The Impact

e20091 Background: 4D CT simulation has been evolved to estimate the internal body motion and considered as a useful tool for intra-thoracic tumor definition. This study aimed to evaluate the impact of using 4D simulation on the planning target volume (PTV) for primary lung tumor. Methods: Patients who underwent CT simulation for primary lung cancer radiotherapy between 2012-2016 using 3D- (free breathing) and 4D- (respiratory gated) institutional protocol were included in this retrospective review. For each patient, gross tumor volume (GTV) was contoured in free breathing scan (3D-GTV), exhale scan (e-GTV) and inhale scan (i-GTV). The corresponding CTVs (3D-CTV, e-CTV and i-CTV) were created by adding 1 cm in all directions. 3D-internal target volume (3D-ITV) was generated by 0.5 cm cranio-caudal expansion of 3D-CTV, while 4D-ITV was created by combination of e-CTV and i-CTV. Subsequently, a 0.5 cm margin was added to generate the 3D-PTV and 4D-PTV respectively. The volumes of 3D-PTV and 4D-PTV were compared to examine the impact of 4D CT simulation on changes in the volume of PTV. Univariable and multivariable analysis were performed to test the impact of volume and location of GTV on the changes of PTV volume by more than 10 % between free breathing and respiratory gated scans. Results: A total of 10 patients were identified. The median [range] GTV, i-GTV, e-GTV volumes were 13.55 [1.44-628.66], 13.17 [1.77-627.36], 12.85 [1.34-630.25] cc respectively. The 3D-CTV, i-CTV, e-CTV volumes were 86.37 [23.76-1209], 84.97 [25.5- 1220.4], 83.40 [23.36-1224.12] cc respectively. 3D-ITV and 4D-ITV median volume was 106.06 [3.99-1422.8], 88.02 [20.51-1338.18] cc respectively. 3D-PTV was significantly larger than the 4D-PTV; median [range] volumes were 182.79 [58.65- 1861.05] vs. 158.21 [52.76-1771.02] cc, p = 0.0068). On multivariable analysis, neither the volume of GTV (p = 0.4917), nor the location of the tumor (peripheral, p = 0.4914 or lower location, p = 0.9594) had an in impact on PTV differences between free breathing and respiratory gated scans. Conclusions: The use of 4D simulation reduces the PTV for primary lung cancer, and it should be routinely implemented in clinical practice regardless the tumor volume or location.

Download Full-text