Can surface imaging improve the patient setup for proton postmastectomy chest wall irradiation?

Batin, Estelle; Depauw, Nicolas; MacDonald, Shannon M.; Lu, Hsiao‐Ming

doi:10.1016/j.prro.2016.02.001

Cited by 43 publications

(70 citation statements)

References 14 publications

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“…The latter represents necessary isocenter shifts and is presented as a proposed couch adjustment expressed in 6‐DOF, three translational and three rotational. The dimensions of the reference surface can be adjusted by the user and governs which part of the live surface is included in the registration …”

Section: Methodsmentioning

confidence: 99%

“…The dimensions of the reference surface can be adjusted by the user and governs which part of the live surface is included in the registration. 15,16 Isocenter shift calculation in C-RAD is a two-step process, consisting of a nonrigid surface registration algorithm to align the live surface to the reference surface, and a volumetric deformable model, which deduces the isocenter position from the surface differences. 10,17 The initial nonrigid registration consists of an iterative process starting with the resampling of the contours into surface meshes of uniform triangles.…”

Section: A Optical Surface Imaging With C-radmentioning

confidence: 99%

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Characterizing a deformable registration algorithm for surface‐guided breast radiotherapy

et al. 2019

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Purpose Surface‐guided radiation therapy (SGRT) is a nonionizing imaging approach for patient setup guidance, intra‐fraction monitoring, and automated breath‐hold gating of radiation treatments. SGRT employs the premise that the external patient surface correlates to the internal anatomy, to infer the treatment isocenter position at time of treatment delivery. Deformations and posture variations are known to impact the correlation between external and internal anatomy. However, the degree, magnitude, and algorithm dependence of this impact are not intuitive and currently no methods exist to assess this relationship. The primary aim of this work was to develop a framework to investigate and understand how a commercial optical surface imaging system (C‐RAD, Uppsala, Sweden), which uses a nonrigid registration algorithm, handles rotations and surface deformations. Methods A workflow consisting of a female torso phantom and software‐introduced transformations to the corresponding digital reference surface was developed. To benchmark and validate the approach, known rigid translations and rotations were first applied. Relevant breast radiotherapy deformations related to breast size, hunching/arching back, distended/deflated abdomen, and an irregular surface to mimic a cover sheet over the lower part of the torso were investigated. The difference between rigid and deformed surfaces was evaluated as a function of isocenter location. Results For all introduced rigid body transformations, C‐RAD computed isocenter shifts were determined within 1 mm and 1˚. Additional translational shifts to correct for rotations as a function of isocenter location were determined with the same accuracy. For yaw setup errors, the difference in shift corrections between a plan with an isocenter placed in the center of the breast (BrstIso) and one located 12 cm superiorly (SCFIso) was 2.3 mm/1˚ in lateral direction. Pitch setup errors resulted in a difference of 2.1 mm/1˚ in vertical direction. For some of the deformation scenarios, much larger differences up to 16 mm and 7˚ in the calculated shifts between BrstIso and SCFIso were observed that could lead to large unintended gaps or overlap between adjacent matched fields if uncorrected. Conclusions The methodology developed lends itself well for quality assurance (QA) of SGRT systems. The deformable C‐RAD algorithm determined accurate shifts for rigid transformations, and this was independent of isocenter location. For surface deformations, the position of the isocenter had considerable impact on the registration result. It is recommended to avoid off‐axis isocenters during treatment planning to optimally utilize the capabilities of the deformable image registration algorithm, especially when multiple isocenters are used with fields that share a field edge.

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Section: Methodsmentioning

confidence: 99%

Section: A Optical Surface Imaging With C-radmentioning

confidence: 99%

Characterizing a deformable registration algorithm for surface‐guided breast radiotherapy

et al. 2019

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“…It is clear that SGRT cannot replace internal imaging for SBRT, but quantifying the effects of adding SGRT to the traditional IGRT chain for SBRT (referred to as SG‐SBRT for the remainder of the text) can help elucidate the benefits of this technology. There is literature describing the benefits of utilizing SGRT for deep inspiration breath‐hold treatments of left‐sided breast cancer patients, other breast cancer treatments, and stereotactic radiosurgery, but limited publications on its use for other sites or for initial positioning of SBRT patients . The aim of this retrospective study is to establish the utility of optical surface imaging for initial patient setup in SBRT treatments and to formulate a proposed initial positioning process by studying the impact of orthogonal kV imaging when SG‐SBRT is used and the effects of reference surface type selection (from treatment planning CT versus camera‐acquired in the room) on its performance.…”

Section: Introductionmentioning

confidence: 99%

Impact of use of optical surface imaging on initial patient setup for stereotactic body radiotherapy treatments

Leong

Padilla

2019

J Applied Clin Med Phys

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PurposeTo evaluate the effectiveness of surface image guidance (SG) for pre‐imaging setup of stereotactic body radiotherapy (SBRT) patients, and to investigate the impact of SG reference surface selection on this process.Methods and materials284 SBRT fractions (SG‐SBRT = 113, non‐SG‐SBRT = 171) were retrospectively evaluated. Differences between initial (pre‐imaging) and treatment couch positions were extracted from the record‐and‐verify system and compared for the two groups. Rotational setup discrepancies were also computed. The utility of orthogonal kVs in reducing CBCT shifts in the SG‐SBRT/non‐SG‐SBRT groups was also calculated. Additionally, the number of CBCTs acquired for setup was recorded and the average for each cohort was compared. These data served to evaluate the effectiveness of surface imaging in pre‐imaging patient positioning and its potential impact on the necessity of including orthogonal kVs for setup. Since reference surface selection can affect SG setup, daily surface reproducibility was estimated by comparing camera‐acquired surface references (VRT surface) at each fraction to the external surface of the planning CT (DICOM surface) and to the VRT surface from the previous fraction.ResultsThe reduction in all initial‐to‐treatment translation/rotation differences when using SG‐SBRT was statistically significant (Rank‐Sum test, α = 0.05). Orthogonal kV imaging kept CBCT shifts below reimaging thresholds in 19%/51% of fractions for SG‐SBRT/non‐SG‐SBRT cohorts. Differences in average number of CBCTs acquired were not statistically significant. The reference surface study found no statistically significant differences between the use of DICOM or VRT surfaces.ConclusionsSG‐SBRT improved pre‐imaging treatment setup compared to in‐room laser localization alone. It decreased the necessity of orthogonal kV imaging prior to CBCT but did not affect the average number of CBCTs acquired for setup. The selection of reference surface did not have a significant impact on initial patient positioning.

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“…Even a displacement of few millimeters could cause significant differences in dose when using a scanning technique. In this regard, surface imaging systems such as those recently proposed by Batin et al [40,41] can be valuable for a more accurate patient positioning.…”

Section: Discussionmentioning

confidence: 99%

Potential skin morbidity reduction with intensity-modulated proton therapy for breast cancer with nodal involvement

et al. 2019

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2019) Potential skin morbidity reduction with intensity-modulated proton therapy for breast cancer with nodal involvement, Acta Oncologica, 58:6, 934-942, ABSTRACT Background: Different modern radiation therapy treatment solutions for breast cancer (BC) and regional nodal irradiation (RNI) have been proposed. In this study, we evaluate the potential reduction in radiation-induced skin morbidity obtained by intensity modulated proton therapy (IMPT) compared with intensity modulated photon therapy (IMXT) for left-side BC and RNI. Material and Methods: Using CT scans from 10 left-side BC patients, treatment plans were generated using IMXT and IMPT techniques. A dose of 50 Gy (or Gy [RBE] for IMPT) was prescribed to the target volume (involved breast, the internal mammary, supraclavicular, and infraclavicular nodes). Two single filed optimization IMPT (IMPT 1 and IMPT 2 ) plans were calculated without and with skin optimization. For each technique, skin dose-metrics were extracted and normal tissue complication probability (NTCP) models from the literature were employed to estimate the risk of radiation-induced skin morbidity. NTCPs for relevant organs-at-risk (OARs) were also considered for reference. The non-parametric Anova (Friedman matched-pairs signed-rank test) was used for comparative analyses. Results: IMPT improved target coverage and dose homogeneity even if the skin was included into optimization strategy (HI IMPT2 ¼ 0.11 vs. HI IMXT ¼ 0.22 and CI IMPT2 ¼ 0.96 vs. CI IMXT ¼ 0.82, p < .05). A significant relative skin risk reduction (RR ¼ NTCP IMPT /NTCP IMXT ) was obtained with IMPT 2 including the skin in the optimization with a RR reduction ranging from 0.3 to 0.9 depending on the analyzed skin toxicity endpoint/model. Both IMPT plans attained significant OARs dose sparing compared with IMXT. As expected, the heart and lung doses were significantly reduced using IMPT. Accordingly, IMPT always provided lower NTCP values. Conclusions: IMPT guarantees optimal target coverage, OARs sparing, and simultaneously minimizes the risk of skin morbidity. The applied model-based approach supports the potential clinical relevance of IMPT for left-side BC and RNI and might be relevant for the setup of cost-effectiveness evaluation strategies based on NTCP predictions, as well as for establishing patient selection criteria. ARTICLE HISTORY

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Can surface imaging improve the patient setup for proton postmastectomy chest wall irradiation?

Cited by 43 publications

References 14 publications

Characterizing a deformable registration algorithm for surface‐guided breast radiotherapy

Characterizing a deformable registration algorithm for surface‐guided breast radiotherapy

Impact of use of optical surface imaging on initial patient setup for stereotactic body radiotherapy treatments

Potential skin morbidity reduction with intensity-modulated proton therapy for breast cancer with nodal involvement

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