Including anatomical variations in robust optimization for head and neck proton therapy can reduce the need of adaptation

Cubillos-Mesías, Macarena; Troost, Esther G.C.; Lohaus, Fabian; Agolli, Linda; Rehm, Maximilian; Richter, Christian; Stützer, Kristin

doi:10.1016/j.radonc.2018.12.008

Cited by 50 publications

(48 citation statements)

References 27 publications

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“…Traditional robust optimization or evaluation is not sufficient to account for the positional and anatomical variation in both target and OARs. Considerable effort is needed for developing better robust optimization algorithms to handle these uncertainties [32]. If this is realized, of advantage IMPT might be made full use in sparing healthy tissue while maintaining target coverage in scenarios of uncertainties.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of plan quality and robustness of IMPT and helical IMRT for cervical cancer

Shang

Wang

et al. 2020

Radiat Oncol

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Background: Both plan quality and robustness were investigated through comparing some dosimetric metrics between intensity modulated proton therapy (IMPT) and helical tomotherapy based intensity modulated radiotherapy (IMRT) for cervical cancer. Methods: Both a spot-scanning robust (SRO) IMPT plan and a helical tomotherapy robust (TRO) IMRT plan were generated for each of 18 patients. In order to evaluate the quality of nominal plans without dose perturbations, planning scores (PS) on clinical target volume (CTV) and five organs at risk (OARs) based on clinical experience, and normal tissue complication probabilities (NTCP) of rectum and sigmoid were calculated based on Lyman-Kutcher-Burman (LKB) model. Dose volume histogram bands width (DVHBW) were calculated in 28 perturbed scenarios to evaluate plan robustness. Results: Compared with TRO, the average scores of SRO nominal plans were higher in target metrics [V 46.8Gy , V 50Gy , Conformity and Homogeneity](16.5 vs. 15.1), and in OARs metrics (60.9 vs. 53.3), including bladder [V 35 ,V 45 , D mean , D 2cc ], rectum [V 40 ,V 45 ,D 2cc ,D max ], bowel [V 35 ,V 40 ,V 45 , D max ], sigmoid [V 40 ,D max ] and femoral heads [V 30 ,D max ]. Meanwhile, NTCP calculation showed that the toxicities of rectum and sigmoid in SRO were lower than those in TRO (rectum: 2.8% vs. 4.8%, p < 0.05; sigmoid: 5.2% vs. 5.7%, p < 0.05). DVHBW in target coverage for the SRO plan was smaller than that for the TRO plan (0.6% vs. 2.1%), which means that the SRO plan generated a more robust plan in target. Conclusion: Better CTV coverage and OAR Sparing were obtained in SRO nominal plan. Based on NTCP calculation, SRO was expected to allow a small reduction in rectal toxicity. Furthermore, SRO generated a more robust plan in CTV target coverage.

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Section: Discussionmentioning

confidence: 99%

Evaluation of plan quality and robustness of IMPT and helical IMRT for cervical cancer

Shang

Wang

et al. 2020

Radiat Oncol

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“…To account for the uncertainty of a generic HLUT for range prediction, considerable safety margins in beam direction are applied directly or indirectly (e.g., with robust optimization techniques), which finally result in a higher dose to healthy tissue close to the target. [7][8][9][10][11] While the acquisition of dual-energy CT (DECT) scans with their ability for an improved material differentiation is already very common for radiological purposes, 12 its routine application in radiotherapy is still scarce. 13,14 For the first time, proton treatment planning was routinely performed on DECTderived pseudo-monoenergetic CT (MonoCT) datasets at the University Proton Therapy Dresden (UPTD) in 2015 still using a HLUT as CT number-to-SPR conversion.…”

Section: Introductionmentioning

confidence: 99%

“…A recent yet unpublished study within the European Particle Therapy Network (EPTN) revealed an inter‐center variation in HLUT‐based range prediction of 2.5% for targets in the head and pelvic region as determined in a phantom study. To account for the uncertainty of a generic HLUT for range prediction, considerable safety margins in beam direction are applied directly or indirectly (e.g., with robust optimization techniques), which finally result in a higher dose to healthy tissue close to the target …”

Section: Introductionmentioning

confidence: 99%

Refinement of the Hounsfield look‐up table by retrospective application of patient‐specific direct proton stopping‐power prediction from dual‐energy CT

et al. 2020

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Background and Purpose: Proton treatment planning relies on an accurate determination of stopping-power ratio (SPR) from x-ray computed tomography (CT). A refinement of the heuristic CTbased SPR prediction using a state-of-the-art Hounsfield look-up table (HLUT) is proposed, which incorporates patient SPR information obtained from dual-energy CT (DECT) in a retrospective patient-cohort analysis. Material and Methods: SPR datasets of 25 brain-tumor patients, 25 prostate-cancer patients, and three nonsmall cell lung-cancer (NSCLC) patients were calculated from clinical DECT scans with the comprehensively validated DirectSPR approach. Based on the median frequency distribution of voxelwise correlations between CT number and SPR within the irradiated volume, a piecewise linear function was specified (DirectSPR-based adapted HLUT). Differences in dose distribution and proton range were assessed for the nonadapted and adapted HLUT in comparison to the DirectSPR method, which has been shown to be an accurate and reliable SPR estimation method. Results: The application of the DirectSPR-based adapted HLUT instead of the nonadapted HLUT reduced the systematic proton range differences from 1.2% (1.1 mm) to À0.1% (0.0 mm) for braintumor patients, 1.7% (4.1 mm) to 0.2% (0.5 mm) for prostate-cancer patients, and 2.0% (2.9 mm) to À0.1% (0.0 mm) for NSCLC patients. Due to the large intra-and inter-patient tissue variability, range differences to DirectSPR larger than 1% remained for the adapted HLUT. Conclusions: The incorporation of patient-specific correlations between CT number and SPR, derived from a retrospective application of DirectSPR to a broad patient cohort, improves the SPR accuracy of the current state-of-the-art HLUT approach. The DirectSPR-based adapted HLUT has been clinically implemented at the University Proton Therapy Dresden (Dresden, Germany) in 2017. This already facilitates the benefits of an improved DECT-based tissue differentiation within clinical routine without changing the general approach for range prediction (HLUT), and represents a further step toward full integration of the DECT-based DirectSPR method for treatment planning in proton therapy.

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confidence: 99%

“…The authors regret the occurrence of minor errors in their published article [1]. The work compares the anatomical robustness of three different planning strategies for head and neck proton therapy by the analysis of weekly and total cumulative dose distribution considering anatomical changes throughout the treatment course by means of weekly control CTs.…”

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confidence: 99%

Corrigendum to “Including anatomical variations in robust optimization for head and neck proton therapy can reduce the need of adaptation” [Radiother Oncol 131 (2019) 127–134]

Cubillos-Mesías

Troost

Lohaus

et al. 2020

Radiotherapy and Oncology

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The authors regret the occurrence of minor errors in their published article [1]. The work compares the anatomical robustness of three different planning strategies for head and neck proton therapy by the analysis of weekly and total cumulative dose distribution considering anatomical changes throughout the treatment course by means of weekly control CTs.It was stated in the original manuscript that the patient data were selected from 20 subsequent patients with locoregionally advanced HNSCC that received IMRT treatment at our institution between January and July 2016. The corrected description of patient data used in our in silico study is that datasets from 20 locally advanced HNSCC patients were included, 17 of whom were treated with IMRT, 2 with double scattered (DS) proton radiotherapy and 1 with a mixed (IMRT/DS) treatment at our institution between August 2015 and July 2016. This changed patient data description does not affect the presented data.It was written in the original manuscript that the PTV-based treatment plans (PTVb) could not account for anatomical changes in 10 cases. The number must be corrected to 12. This correction does not change the general rating of anatomical robustness of the three investigated planning approaches as the classical robust optimization (cRO) and the anatomical robust optimization (aRO) could not account for anatomical changes only in 5 cases and 1 case, respectively.Within this corrigendum, the authors would furthermore like to clarify and correct some misleading statements for the organ at risk (OAR) doses. (1) It was stated that doses to the OARs remained below the constraints in the nominal plans. Actually, this is only correct for the planning OARs, defined as the OAR volumes outside the CTV, but not for the total OAR volumes whose dose statistics were given in Table 1. The authors would like to add for clarification that the nominal plans could not meet the dosimetric constraints for the total OAR volumes in several cases for the ipsilateral parotid gland (9ÂPTVb, 8ÂcRO, 8ÂaRO), the larynx (8ÂPTVb, 9ÂcRO, 8ÂaRO) and the pharyngeal constrictor muscles (17ÂPTVb, 18ÂcRO, 18ÂaRO). (2) The original manuscript reported the increase of the larynx mean dose in the cumulative dose distributions, and stated that the remaining OAR dose parameters presented no major deviations between the nominal and cumulative doses. This statement referred just to the change of the median values given in Table 1. The authors would like to specify that the mean increase of the investigated dose parameter in the cumulative compared to the nominal dose distribution was always <1.3 Gy. However, major deviations with increases of more than 5 Gy occurred in individual cases for the mean dose of the larynx (2ÂPTVb, 2ÂcRO, 2ÂaRO), the ipsilateral parotid gland (1ÂPTVb) and the esophagus inlet muscle (1ÂPTVb). The presented original article focussed on the investigation of target coverage loss when analyzing the anatomical robustness of the three planning approaches and the authors did not consider ...

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Including anatomical variations in robust optimization for head and neck proton therapy can reduce the need of adaptation

Cited by 50 publications

References 27 publications

Evaluation of plan quality and robustness of IMPT and helical IMRT for cervical cancer

Evaluation of plan quality and robustness of IMPT and helical IMRT for cervical cancer

Refinement of the Hounsfield look‐up table by retrospective application of patient‐specific direct proton stopping‐power prediction from dual‐energy CT

Corrigendum to “Including anatomical variations in robust optimization for head and neck proton therapy can reduce the need of adaptation” [Radiother Oncol 131 (2019) 127–134]

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