Denoised and texture enhanced MVCT to improve soft tissue conspicuity

Sheng, Ke; Gou, Shuiping; Wu, Jiaolong; Qi, S

doi:10.1118/1.4894714

Cited by 55 publications

(46 citation statements)

References 36 publications

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“…Similarly, Case et al In our study, we observed an average liver motion distance in the direction of the Y -axis of 4.5 mm when abdominal compression was applied, a larger magnitude than that reported by both Eccles et al and Case et al In our study, the total abdominal compression time experienced by patients was about 25 min, including setup, megavoltage CT, imageguided scan, and treatment. 19 This time is much longer than that of patients in the studies of Eccles et al and Case et al; therefore, the increased AC time experienced by patients in our study is likely responsible for the increased magnitude of liver motion observed in our study compared to others.…”

Section: Discussioncontrasting

confidence: 49%

4D‐CT scans reveal reduced magnitude of respiratory liver motion achieved by different abdominal compression plate positions in patients with intrahepatic tumors undergoing helical tomotherapy

Zhou

Chen

et al. 2016

Medical Physics

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Purpose: While abdominal compression (AC) can be used to reduce respiratory liver motion in patients receiving helical tomotherapy for hepatocellular carcinoma, the nature and extent of this effect is not well described. The purpose of this study was to evaluate the changes in magnitude of three-dimensional liver motion with abdominal compression using four-dimensional (4D) computed tomography (CT) images of several plate positions. Methods: From January 2012 to October 2015, 72 patients with intrahepatic carcinoma and divided into four groups underwent 4D-CT scans to assess respiratory liver motion. Of the 72 patients, 19 underwent abdominal compression of the cephalic area between the subxiphoid and umbilicus (group A), 16 underwent abdominal compression of the caudal region between the subxiphoid area and the umbilicus (group B), 11 patients underwent abdominal compression of the caudal umbilicus (group C), and 26 patients remained free breathing (group D). 4D-CT images were sorted into ten-image series, according to the respiratory phase from the end inspiration to the end expiration, and then transferred to treatment planning software. All liver contours were drawn by a single physician and confirmed by a second physician. Liver relative coordinates were automatically generated to calculate the liver respiratory motion in different axial directions to compile the 10 ten contours into a single composite image. Differences in respiratory liver motion were assessed with a one-way analysis of variance test of significance. Results: The average respiratory liver motion in the Y axial direction was 4.53 ± 1.16, 7.56 ± 1.30, 9.95 ± 2.32, and 9.53 ± 2.62 mm in groups A, B, C, and D, respectively, with a significant change among the four groups (p < 0.001). Abdominal compression was most effective in group A (compression plate on the subxiphoid area), with liver displacement being 2.53 ± 0.93, 4.53 ± 1.16, and 2.14 ± 0.92 mm on the X-, Y -, and Z-axes, respectively. There was no significant difference in respiratory liver motion between group C (displacement: 3.23 ± 1.47, 9.95 ± 2.32, and 2.92 ± 1.10 mm on the X-, Y -, and Z-axes, respectively) and group D (displacement: 3.35 ± 1.55, 9.53 ± 2.62, and 3.35 ± 1.73 mm on the X-, Y -, and Z-axes, respectively). Abdominal compression was least effective in group C (compression on caudal umbilicus), with liver motion in this group similar to that of free-breathing patients (group D). Conclusions: 4D-CT scans revealed significant liver motion control via abdominal compression of the subxiphoid area; however, this control of liver motion was not observed with compression of the caudal umbilicus. The authors, therefore, recommend compression of the subxiphoid area in patients undergoing external radiotherapy for intrahepatic carcinoma. C 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license

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Section: Discussioncontrasting

confidence: 49%

4D‐CT scans reveal reduced magnitude of respiratory liver motion achieved by different abdominal compression plate positions in patients with intrahepatic tumors undergoing helical tomotherapy

Zhou

Chen

et al. 2016

Medical Physics

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“…Of course, high-dose imaging, deionized and texture-enhanced MVCT would be made possible to improve the soft-tissue contrast. 30,31 The delineation errors should not significantly affect the observed results, as only the relative and CTN mean change in a structure is of interest here.…”

Section: Discussionmentioning

confidence: 99%

Radiation-induced CT number changes in GTV and parotid glands during the course of radiation therapy for nasopharyngeal cancer

Yang

et al. 2016

BJR

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Objective: To investigate the changes in CT number (CTN) in gross tumour volume (GTV) and organs at risk (OARs) during the course of radiation therapy (RT) for nasopharyngeal cancer (NPC). Methods: Daily megavoltage CT (MVCT) data collected from 30 patients with NPC treated with a prescription dose of 70 Gy in 30-33 fractions using helical tomotherapy were retrospectively analyzed. The contours of GTV and OARs on daily MVCTs were obtained by populating the planning contours from planning CT to daily MVCTs with manual editing, if necessary. The changes of GTV and OAR volumes and the histograms of CTN in the GTV and OARs during the course of RT delivery were analyzed. Results: Volumes of GTV and parotid glands were reduced during the course of radiation treatment, with an average shrinkage rate of 0.23% per day (range, 0.02-0.8%) and 1.2% per day (range, 0.2-2.3%), respectively. The mean CTN changes in GTV and ipsilateral and contralateral parotid glands were reduced by 52 6 35 HU, 18 6 20 HU and 17 6 22 HU, respectively. For GTV, the CTN and GTV volume decreases were found to be correlated with each other (p , 0.0001). No noticeable CTN change was found in the spinal cord and non-specified tissue irradiated with low doses. Conclusion: The CTN changes in GTV and parotids are measurable during the delivery of fractionated radiotherapy for NPC, were associated with the doses received (the number of fractions delivered) and were patient specific. Advances in knowledge: The CTN change during radiotherapy is dose dependent and is measurable for NPC.

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“…Unfortunately, due to Compton effect prominence in MV beams, soft tissue contrast is poor in an MVCT image, thus deformable registration and OAR/target delineation is challenging without considerable contrast enhancing algorithms. 15,16 The "CT-on-rails" concept is a fan-beam kV-CT mounted on rails that, in mechanical concert with a specialized couch, can provide diagnostic-quality daily images for online ART purposes. This setup overcomes the image quality problems with CBCT and MVCT-it is a viable solution to the problem of acquiring high-quality daily image sets by making the daily image and the plan CT the same modality.…”

Section: Daily In-room Treatment Imagingmentioning

confidence: 99%

Online Adaptive Radiation Therapy

Lim‐Reinders

Keller

Al-Ward

et al. 2017

International Journal of Radiation Oncology*Biology*Physics

166

135

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Denoised and texture enhanced MVCT to improve soft tissue conspicuity

Abstract: The authors showed that it is feasible to extract more soft tissue contrast information from the noisy MVCT images using a nonlocal means 3D block matching method in combination with saliency maps, revealing information that was originally unperceivable to human observers.

Cited by 55 publications

References 36 publications

4D‐CT scans reveal reduced magnitude of respiratory liver motion achieved by different abdominal compression plate positions in patients with intrahepatic tumors undergoing helical tomotherapy

4D‐CT scans reveal reduced magnitude of respiratory liver motion achieved by different abdominal compression plate positions in patients with intrahepatic tumors undergoing helical tomotherapy

Radiation-induced CT number changes in GTV and parotid glands during the course of radiation therapy for nasopharyngeal cancer

Online Adaptive Radiation Therapy

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