The Impact of Anatomic Change on Pencil Beam Scanning in the Treatment of Oropharynx Cancer

Thomson, David J; Teo, Boon-Keng; Ong, Ashley Li Kuan; Ang, Khong Wei; Kirk, Maura; Ahn, Peter H.; Lukens, John N.; Swisher‐McClure, Samuel; Liptrot, Tom; Solberg, T.D.; Slevin, N.; Lin, Alexander

doi:10.14338/ijpt-15-00002.1

Cited by 9 publications

(6 citation statements)

References 24 publications

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“…[6][7][8] However, enhanced conformity comes along with an increased sensitivity to anatomical variations during the course of fractionated treatment. [9][10][11] For H&N tumor patients, particularly weight-loss but also tumor shrinkage can lead to considerable anatomical changes on a time scale of days to weeks. 12 For prostate cancer patients, changes in bladder and rectum filling, also impacting the position of the clinical and planning target volumes (CTV, PTV), can evolve within hours or even minutes, such that the patient anatomy might strongly vary from fraction to fraction.…”

Section: Introductionmentioning

confidence: 99%

Investigating deformable image registration and scatter correction for CBCT‐based dose calculation in adaptive IMPT

et al. 2016

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International audiencePurpose:This work aims at investigating intensity corrected cone-beam x-ray computed tomography (CBCT) images for accurate dose calculation in adaptive intensity modulated proton therapy (IMPT) for prostate and head and neck (H&N) cancer. A deformable image registration (DIR)-based method and a scatter correction approach using the image data obtained from DIR as prior are characterized and compared on the basis of the same clinical patient cohort for the first time.Methods:Planning CT (pCT) and daily CBCT data (reconstructed images and measured projections) of four H&N and four prostate cancer patients have been considered in this study. A previously validated Morphons algorithm was used for DIR of the planning CT to the current CBCT image, yielding a so-called virtual CT (vCT). For the first time, this approach was translated from H&N to prostate cancer cases in the scope of proton therapy. The warped pCT images were also used as prior for scatter correction of the CBCT projections for both tumor sites. Single field uniform dose and IMPT (only for H&N cases) treatment plans have been generated with a research version of a commercial planning system. Dose calculations on vCT and scatter corrected CBCT (CBCT cor) were compared by means of the proton range and a gamma-index analysis. For the H&N cases, an additional diagnostic replanning CT (rpCT) acquired within three days of the CBCT served as additional reference. For the prostate patients, a comprehensive contour comparison of CBCT and vCT, using a trained physician’s delineation, was performed.Results:A high agreement of vCT and CBCT cor was found in terms of the proton range and gamma-index analysis. For all patients and indications between 95% and 100% of the proton dose profiles in beam’s eye view showed a range agreement of better than 3 mm. The pass rate in a (2%,2 mm) gamma-comparison was between 96% and 100%. For H&N patients, an equivalent agreement of vCT and CBCT cor to the reference rpCT was observed. However, for the prostate cases, an insufficient accuracy of the vCT contours retrieved from DIR was found, while the CBCT cor contours showed very high agreement to the contours delineated on the raw CBCT.Conclusions:For H&N patients, no considerable differences of vCT and CBCT cor were found. For prostate cases, despite the high dosimetric agreement, the DIR yields incorrect contours, probably due to the more pronounced anatomical changes in the abdomen and the reduced soft-tissue contrast in the CBCT. Using the vCT as prior, these inaccuracies can be overcome and images suitable for accurate delineation and dose calculation in CBCT-based adaptive IMPT can be retrieved from scatter correction of the CBCT projections

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Section: Introductionmentioning

confidence: 99%

Investigating deformable image registration and scatter correction for CBCT‐based dose calculation in adaptive IMPT

et al. 2016

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“…Robustly optimized, multifield IMPT is superior to single-field optimization [ 42 ], and recommended. Additionally, given potential daily variation in anatomy at the skull base, as well as anatomic change secondary to disease response, high-quality daily anatomic imaging (such as with cone-beam computed tomography) is needed for quality assurance and to determine if/when plan adaptation is required [ 43 ].…”

Section: Nasopharynx Cancermentioning

confidence: 99%

PTCOG Head and Neck Subcommittee Consensus Guidelines on Particle Therapy for the Management of Head and Neck Tumors

Lin

Chang²,

Grover

et al. 2021

International Journal of Particle Therapy

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Purpose: Radiation therapy is a standard modality in the treatment for cancers of the head and neck, but is associated with significant short- and long-term side effects. Proton therapy, with its unique physical characteristics, can deliver less dose to normal tissues, resulting in fewer side effects. Proton therapy is currently being used for the treatment of head and neck cancer, with increasing clinical evidence supporting its use. However, barriers to wider adoption include access, cost, and the need for higher-level evidence. Methods: The clinical evidence for the use of proton therapy in the treatment of head and neck cancer are reviewed here, including indications, advantages, and challenges. Results: The Particle Therapy Cooperative Group Head and Neck Subcommittee task group provides consensus guidelines for the use of proton therapy for head and neck cancer. Conclusion: This report can be used as a guide for clinical use, to understand clinical trials, and to inform future research efforts.

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“…The issue of standardising CTV delineation is as relevant with IMPT, notwithstanding the unique treatment planning aspects for IMPT target volumes which cannot be based on geometric margin expansion alone, owing to increased range uncertainty with resultant increased sensitivity to set-up and anatomical changes. Degradation of the dose distribution for both the target volumes and OARs can be proportionately worse for IMPT compared to IMRT over the entire course of treatment, resulting in less than anticipated therapeutic benefits for IMPT [ 16 , 17 ]. Studies evaluating robust planning parameters specific to oropharyngeal cancer have recently emerged and robustness settings do influence the dose to OARs with possible clinical impact [ 18 , 19 ].…”

Section: Clinical Target Volume Definitionmentioning

confidence: 99%

Assessing Novel Drugs and Radiation Technology in the Chemoradiation of Oropharyngeal Cancer

et al. 2018

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Integrating immunotherapy, proton therapy and biological dose escalation into the definitive chemoradiation of oropharyngeal cancer poses several challenges. Reliable and reproducible data must be obtained in a timely fashion. However, despite recent international radiotherapy contouring guidelines, controversy persists as to the applicability of such guidelines to all cases. Similarly, a lack of consensus exists concerning both the definition of the organ at risk for oral mucositis and the most appropriate endpoint to measure for this critical toxicity. Finally, the correlation between early markers of efficacy such as complete response on PET CT following treatment and subsequent survival needs elucidation for biological subsets of oropharyngeal cancer.

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The Impact of Anatomic Change on Pencil Beam Scanning in the Treatment of Oropharynx Cancer

Cited by 9 publications

References 24 publications

Investigating deformable image registration and scatter correction for CBCT‐based dose calculation in adaptive IMPT

Investigating deformable image registration and scatter correction for CBCT‐based dose calculation in adaptive IMPT

PTCOG Head and Neck Subcommittee Consensus Guidelines on Particle Therapy for the Management of Head and Neck Tumors

Assessing Novel Drugs and Radiation Technology in the Chemoradiation of Oropharyngeal Cancer

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