Investigating CT to CBCT image registration for head and neck proton therapy as a tool for daily dose recalculation

Landry, Guillaume; Nijhuis, Reinoud; Dedes, G.; Handrack, Josefine; Thieke, Christian; Janssens, Guillaume; Xivry, Jonathan Orban de; Reiner, M. J.; Kamp, Florian; Wilkens, Jan J.; Paganelli, Chiara; Riboldi, Marco; Baroni, Guido; Ganswindt, Ute; Belka, Claus; Parodi, Katia

doi:10.1118/1.4908223

Cited by 121 publications

(155 citation statements)

References 43 publications

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“…6. These results were slightly better than the

2.8 \pm 0.2 mm

1.0 \pm 2.0 mm

, and

1.0 \pm 0.2 mm

errors observed in similar studies that employed different DIR algorithms 7 , 24 , 25 , 26 …”

Section: Resultscontrasting

confidence: 51%

“…Advanced analysis tools to evaluate the distal range of the proton beam, polar WET maps, tracking PDR changes as well as the potential to compute the “dose of the day” 7 , 26 using the cCBCT, are some applications that may be developed using volumetric imaging to leverage the maximum benefit from the unique properties of proton dose distribution. If this analysis can be automated, it may be possible to use CBCT to trigger further action such as dose calculation on the cCBCT or resimulation and replanning.…”

Section: Discussionmentioning

confidence: 99%

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Quantitative assessment of anatomical change using a virtual proton depth radiograph for adaptive head and neck proton therapy

Wang

Yin

Zhang

et al. 2016

J Applied Clin Med Phys

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The aim of this work is to demonstrate the feasibility of using water‐equivalent thickness (WET) and virtual proton depth radiographs (PDRs) of intensity corrected cone‐beam computed tomography (CBCT) to detect anatomical change and patient setup error to trigger adaptive head and neck proton therapy. The planning CT (pCT) and linear accelerator (linac) equipped CBCTs acquired weekly during treatment of a head and neck patient were used in this study. Deformable image registration (DIR) was used to register each CBCT with the pCT and map Hounsfield units (HUs) from the planning CT (pCT) onto the daily CBCT. The deformed pCT is referred as the corrected CBCT (cCBCT). Two dimensional virtual lateral PDRs were generated using a ray‐tracing technique to project the cumulative WET from a virtual source through the cCBCT and the pCT onto a virtual plane. The PDRs were used to identify anatomic regions with large variations in the proton range between the cCBCT and pCT using a threshold of 3 mm relative difference of WET and 3 mm search radius criteria. The relationship between PDR differences and dose distribution is established. Due to weight change and tumor response during treatment, large variations in WETs were observed in the relative PDRs which corresponded spatially with an increase in the number of failing points within the GTV, especially in the pharynx area. Failing points were also evident near the posterior neck due to setup variations. Differences in PDRs correlated spatially to differences in the distal dose distribution in the beam's eye view. Virtual PDRs generated from volumetric data, such as pCTs or CBCTs, are potentially a useful quantitative tool in proton therapy. PDRs and WET analysis may be used to detect anatomical change from baseline during treatment and trigger further analysis in adaptive proton therapy.PACS number(s): 87.55‐x, 87.55.‐D, 87.57.Q‐

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“…6. These results were slightly better than the

2.8 \pm 0.2 mm

1.0 \pm 2.0 mm

, and

1.0 \pm 0.2 mm

errors observed in similar studies that employed different DIR algorithms 7 , 24 , 25 , 26 …”

Section: Resultscontrasting

confidence: 51%

Section: Discussionmentioning

confidence: 99%

Quantitative assessment of anatomical change using a virtual proton depth radiograph for adaptive head and neck proton therapy

Wang

Yin

Zhang

et al. 2016

J Applied Clin Med Phys

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“…18,20 However, we believe it necessary for this to be independently conducted since the residual HU errors after the scatter correction would have different effects on proton dose calculations compared to photon cases. Moreover, this validation cannot be done in real patient images, as there would be no ground truth of CT ref to compare with daily CBCT images unless CT and CBCT images are acquired at the same patient setup as pointed out by Landry et al 12 Recently, Landry et al 12,13 investigated the feasibility of proton dose calculations on a virtual CT image using deformable image registration between plan CT and daily CBCT images. Even though they demonstrated a promising WEPL error (2% error of the proton range), they encountered residual DIR errors of 2-3 mm which potentially degrade the effectiveness T III.…”

Section: Discussionmentioning

confidence: 99%

“…However, there have been few studies on CBCT imaging for APT. 12,13 It is expected that the HU accuracy of CBCT is more crucial in APT than it is in ART, because small HU differences may cause range errors and absolute dose errors, which will in turn lead to reduced integrity of the dose calculation. 14 To date, no study has demonstrated proton dose calculation or treatment planning on either raw or scatter-corrected CBCT images.…”

Section: Introductionmentioning

confidence: 99%

Proton dose calculation on scatter‐corrected CBCT image: Feasibility study for adaptive proton therapy

et al. 2015

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Purpose: To demonstrate the feasibility of proton dose calculation on scatter-corrected cone-beam computed tomographic (CBCT) images for the purpose of adaptive proton therapy. Methods: CBCT projection images were acquired from anthropomorphic phantoms and a prostate patient using an on-board imaging system of an Elekta infinity linear accelerator. Two previously introduced techniques were used to correct the scattered x-rays in the raw projection images: uniform scatter correction (CBCT us ) and a priori CT-based scatter correction (CBCT ap ). CBCT images were reconstructed using a standard FDK algorithm and GPU-based reconstruction toolkit. Soft tissue ROI-based HU shifting was used to improve HU accuracy of the uncorrected CBCT images and CBCT us , while no HU change was applied to the CBCT ap . The degree of equivalence of the corrected CBCT images with respect to the reference CT image (CT ref ) was evaluated by using angular profiles of water equivalent path length (WEPL) and passively scattered proton treatment plans. The CBCT ap was further evaluated in more realistic scenarios such as rectal filling and weight loss to assess the effect of mismatched prior information on the corrected images. Results: The uncorrected CBCT and CBCT us images demonstrated substantial WEPL discrepancies (7.3 ± 5.3 mm and 11.1 ± 6.6 mm, respectively) with respect to the CT ref , while the CBCT ap images showed substantially reduced WEPL errors (2.4 ± 2.0 mm). Similarly, the CBCT ap -based treatment plans demonstrated a high pass rate (96.0% ± 2.5% in 2 mm/2% criteria) in a 3D gamma analysis. Conclusions: A priori CT-based scatter correction technique was shown to be promising for adaptive proton therapy, as it achieved equivalent proton dose distributions and water equivalent path lengths compared to those of a reference CT in a selection of anthropomorphic phantoms. C 2015 American Association of Physicists in Medicine. [http://dx

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“…Yang et al investigated that dose calculation based on modified CBCT (mCBCT) was more accurate than directly on the basis of CBCT 18. Landry et al reported that dose distributions calculated on the modified CBCT agreed well to those calculated on the CT when using gamma index evaluation, as well as DVH statistics based on the same contours 19. This means that mCBCT has potential to account for interfractional dosimetric uncertainness.…”

Section: Introductionmentioning

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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Investigating CT to CBCT image registration for head and neck proton therapy as a tool for daily dose recalculation

Cited by 121 publications

References 43 publications

Quantitative assessment of anatomical change using a virtual proton depth radiograph for adaptive head and neck proton therapy

Quantitative assessment of anatomical change using a virtual proton depth radiograph for adaptive head and neck proton therapy

Proton dose calculation on scatter‐corrected CBCT image: Feasibility study for adaptive proton therapy

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

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