ART for head and neck patients: On the difference between VMAT and IMPT

Góra, J.; Kueß, Peter; Andrzejewski, Piotr; Knäusl, B.; Paskeviciute, Brigita; Altorjai, Gabriela; Georg, Dietmar

doi:10.3109/0284186x.2015.1028590

Cited by 34 publications

(29 citation statements)

References 27 publications

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“…A limitation of the presented analysis is the use of nominal dose distributions. As Müller et al ( 40 ) and Góra et al ( 41 ) showed, IMPT treatment plans are more prone to dose distortions originating from anatomical changes of the patients. Such changes can decrease the dose conformity to the target volume and thus deteriorate the TCP.…”

Section: Discussionmentioning

confidence: 96%

Increase in Tumor Control and Normal Tissue Complication Probabilities in Advanced Head-and-Neck Cancer for Dose-Escalated Intensity-Modulated Photon and Proton Therapy

et al. 2015

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IntroductionPresently used radiochemotherapy regimens result in moderate local control rates for patients with advanced head-and-neck squamous cell carcinoma (HNSCC). Dose escalation (DE) may be an option to improve patient outcome, but may also increase the risk of toxicities in healthy tissue. The presented treatment planning study evaluated the feasibility of two DE levels for advanced HNSCC patients, planned with either intensity-modulated photon therapy (IMXT) or proton therapy (IMPT).Materials and methodsFor 45 HNSCC patients, IMXT and IMPT treatment plans were created including DE via a simultaneous integrated boost (SIB) in the high-risk volume, while maintaining standard fractionation with 2 Gy per fraction in the remaining target volume. Two DE levels for the SIB were compared: 2.3 and 2.6 Gy. Treatment plan evaluation included assessment of tumor control probabilities (TCP) and normal tissue complication probabilities (NTCP).ResultsAn increase of approximately 10% in TCP was estimated between the DE levels. A pronounced high-dose rim surrounding the SIB volume was identified in IMXT treatment. Compared to IMPT, this extra dose slightly increased the TCP values and to a larger extent the NTCP values. For both modalities, the higher DE level led only to a small increase in NTCP values (mean differences <2%) in all models, except for the risk of aspiration, which increased on average by 8 and 6% with IMXT and IMPT, respectively, but showed a considerable patient dependence.ConclusionBoth DE levels appear applicable to patients with IMXT and IMPT since all calculated NTCP values, except for one, increased only little for the higher DE level. The estimated TCP increase is of relevant magnitude. The higher DE schedule needs to be investigated carefully in the setting of a prospective clinical trial, especially regarding toxicities caused by high local doses that lack a sound dose–response description, e.g., ulcers.

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Section: Discussionmentioning

confidence: 96%

Increase in Tumor Control and Normal Tissue Complication Probabilities in Advanced Head-and-Neck Cancer for Dose-Escalated Intensity-Modulated Photon and Proton Therapy

et al. 2015

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“…This allows for an increased dose to the tumor at a reduced integral dose to the normal tissue and organs at risk (OAR) with respect to conventional photon therapy. Two of the indications potentially benefiting from the more conformal dose distributions in IMPT are tumors in the head and neck (H&N) region, [3][4][5] as well as tumors of the prostate. [6][7][8] However, enhanced conformity comes along with an increased sensitivity to anatomical variations during the course of fractionated treatment.…”

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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“…The way of adaptive treatment planning and dose accumulation in A-IMXT and A-IMPT has been based on the method previously described by Goras et al 18 and is illustrated in Fig. 1.…”

Section: A-impt Planningmentioning

confidence: 99%

Potential benefits of adaptive intensity modulated proton therapy in nasopharyngeal carcinomas: a planning comparison study

Minatogawa

Yasuda²,

Dekura

et al. 2020

Preprint

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Background To investigate potential advantages of adaptive intensity modulated proton beam therapy (A-IMPT) by comparing it to adaptive intensity modulated X-ray therapy (A-IMXT) for nasopharyngeal carcinomas (NPC). Methods Six patients with NPC treated with A-IMXT (step and shoot approach) and concomitant chemotherapy between 2015 and 2016 were selected. In the actual treatment, 46 Gy in 23fr fractions was prescribed using the initial plan and 24 Gy/12fr was prescribed using an adapted plan thereafter. New treatment planning of A-IMPT was made for the same patients using equivalent dose fractionation schedule and dose constraints. The dose volume statistics based on deformable images and dose accumulation was used in the comparison of A-IMXT with A-IMPT. Results The mean doses to the right parotid gland (p = 0.004), left parotid gland (p = 0.012), the oral cavity (p < 0.001), the thyroid gland (p = 0.047), the supraglottic larynx (p < 0.001), the glottic larynx (p = 0.001), the superior pharyngeal constrictor muscle (PCM) (p < 0.001), the middle PCM (p = 0.002), the inferior PCM (p < 0.001), and the cricopharyngeal muscle (p = 0.031) in A-IMPT are statistically significantly lower than those of A-IMRT with the statistical significance. The mean dose to the oral cavity, supraglottic larynx, and glottic larynx were all reduced by more than 20 GyE. Conclusion The adaptive approach is suggested to enhance the potential benefit of IMPT compared to IMXT to reduce adverse effects for patients with NPC.

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ART for head and neck patients: On the difference between VMAT and IMPT

Cited by 34 publications

References 27 publications

Increase in Tumor Control and Normal Tissue Complication Probabilities in Advanced Head-and-Neck Cancer for Dose-Escalated Intensity-Modulated Photon and Proton Therapy

Increase in Tumor Control and Normal Tissue Complication Probabilities in Advanced Head-and-Neck Cancer for Dose-Escalated Intensity-Modulated Photon and Proton Therapy

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

Potential benefits of adaptive intensity modulated proton therapy in nasopharyngeal carcinomas: a planning comparison study

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