Potential underestimation of the internal target volume (ITV) from free‐breathing CBCT

Vergalasova, Irina; Mäurer, J; Yin, Fang‐Fang

doi:10.1118/1.3613153

Cited by 63 publications

(69 citation statements)

References 63 publications

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“…For the Symmetry protocol, the motion artifacts are greatly suppressed compared to the Chest; however, because of the poor image quality in each phase, the measurement of the ITV volume (union of the images at 0% and 50%, corresponding to the maximum inspiration and maximum expiration phases) becomes less accurate and in our case comparable to the Chest (Table 2). As observed by Vergalasova et al, (25) an underestimation of the ITV could lead to an improper alignment of the planning CT ITV with respect to the daily CBCT ITV. However, even if the results obtained from both protocols were similar, a precise tumor volume definition was harder to achieve with 3D CBCT because of the presence of larger artifacts, such as the duplication structure.…”

Section: Discussionmentioning

confidence: 88%

Difference in performance between 3D and 4D CBCT for lung imaging: a dose and image quality analysis

Thengumpallil

Smith

Monnin

et al. 2016

J Applied Clin Med Phys

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The study was to describe and to compare the performance of 3D and 4D CBCT imaging modalities by measuring and analyzing the delivered dose and the image quality. The 3D (Chest) and 4D (Symmetry) CBCT Elekta XVI lung IGRT protocols were analyzed. Dose profiles were measured with TLDs inside a dedicated phantom. The dosimetric indicator cone‐beam dose index (CBDI) was evaluated. The image quality analysis was performed by assessing the contrast transfer function (CTF), the noise power spectrum (NPS) and the noise‐equivalent quanta (NEQ). Artifacts were also evaluated by simulating irregular breathing variations. The two imaging modalities showed different dose distributions within the phantom. At the center, the 3D CBCT delivered twice the dose of the 4D CBCT. The CTF was strongly reduced by motion compared to static conditions, resulting in a CTF reduction of 85% for the 3D CBCT and 65% for the 4D CBCT. The amplitude of the NPS was two times higher for the 4D CBCT than for the 3D CBCT. In the presence of motion, the NEQ of the 4D CBCT was 50% higher than the 3D CBCT. In the presence of breathing irregularities, the 4D CBCT protocol was mainly affected by view‐aliasing artifacts, which were typically cone‐beam artifacts, while the 3D CBCT protocol was mainly affected by duplication artifacts. The results showed that the 4D CBCT ensures a reasonable dose and better image quality when moving targets are involved compared to 3D CBCT. Therefore, 4D CBCT is a reliable imaging modality for lung free‐breathing radiation therapy.PACS number(s): 87.57.C‐, 87.57.uq, 87.53.Ly

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Section: Discussionmentioning

confidence: 88%

Difference in performance between 3D and 4D CBCT for lung imaging: a dose and image quality analysis

Thengumpallil

Smith

Monnin

et al. 2016

J Applied Clin Med Phys

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“…[31][32][33] However, 4DCBCT has not been analysed for ITV definition, especially for different gantry rotation speeds. Therefore, the purpose of this study was to evaluate the Elekta 4DCBCT system for deriving ITV with different gantry rotation speeds.…”

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confidence: 99%

Evaluating the four-dimensional cone beam computed tomography with varying gantry rotation speed

Yoganathan¹,

Das²,

Ali³

et al. 2016

BJR

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“…This study also assumed perfect bone to bone matching to achieve zero setup errors. Furthermore, due to the respiratory and liver motion during CBCT scan, the CBCT indicates an intricate effect of multiple respiratory phase 30. Moreover, the often significant intra‐fraction motion31 was assumed to be zero in this study.…”

Section: Discussionmentioning

confidence: 99%

Investigation of dosimetric variations of liver radiotherapy using deformable registration of planning CT and cone‐beam CT

Huang

Chen

et al. 2016

J Applied Clin Med Phys

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Many patients with technically unresectable or medically inoperable hepatocellular carcinoma (HCC) had hepatic anatomy variations as a result of interfraction deformation during fractionated radiotherapy. We conducted this retrospective study to investigate interfractional normal liver dosimetric consequences via reconstructing weekly dose in HCC patients. Twenty‐three patients with HCC received conventional fractionated three‐dimensional conformal radiation therapy (3DCRT) were enrolled in this retrospective investigation. Among them, seven patients had been diagnosed of radiation‐induced liver disease (RILD) and the other 16 patients had good prognosis after treatment course. The cone‐beam CT (CBCT) scans were acquired once weekly for each patient throughout the treatment, deformable image registration (DIR) of planning CT (pCT) and CBCT was performed to acquire modified CBCT (mCBCT), and the structural contours were propagated by the DIR. The same plan was applied to mCBCT to perform dose calculation. Weekly dose distribution was displayed on the pCT dose space and compared using dose difference, target coverage, and dose volume histograms. Statistical analysis was performed to identify the significant dosimetric variations. Among the 23 patients, the three weekly normal liver D50 increased by 0.2 Gy, 4.2 Gy, and 4.7 Gy, respectively, for patients with RILD, and 1.0 Gy, 2.7 Gy, and 3.1 Gy, respectively, for patients without RILD. Mean dose to the normal liver (Dmean) increased by 0.5 Gy, 2.6 Gy, and 4.0 Gy, respectively, for patients with RILD, and 0.4 Gy, 3.1 Gy, and 3.4 Gy, respectively, for patients without RILD. Regarding patients with RILD, the average values of the third weekly D50 and Dmean were both over hepatic radiation tolerance, while the values of patients without RILD were below. The dosimetric consequence showed that the liver dose between patients with and without RILD were different relative to the planned dose, and the RILD patients suffered from liver dose over hepatic radiation tolerance. Evaluation of routinely acquired CBCT images during radiation therapy provides biological information on the organs at risk, and dose estimation based on mCBCT could potentially form the basis for personalized response adaptive therapy.

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Potential underestimation of the internal target volume (ITV) from free‐breathing CBCT

Abstract: The ITV may be underestimated in a FB-CBCT image when a patient's respiratory pattern is characterized by a disparate length of time spent in inspiration versus expiration. Missing the full target motion information during on-board verification imaging may result in localization errors.

Cited by 63 publications

References 63 publications

Difference in performance between 3D and 4D CBCT for lung imaging: a dose and image quality analysis

Difference in performance between 3D and 4D CBCT for lung imaging: a dose and image quality analysis

Evaluating the four-dimensional cone beam computed tomography with varying gantry rotation speed

Investigation of dosimetric variations of liver radiotherapy using deformable registration of planning CT and cone‐beam CT

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