A Beam-Specific Planning Target Volume (PTV) Design for Proton Therapy to Account for Setup and Range Uncertainties

Park, Peter Chul; Zhu, Xiaorong Ronald; Lee, Andrew K.; Sahoo, Narayan; Melancon, Adam David; Zhang, Lifei; Dong, Lei

doi:10.1016/j.ijrobp.2011.05.011

Cited by 155 publications

(109 citation statements)

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“…Strictly speaking, the PTV concept commonly used in photon therapy cannot be directly used for proton therapy because the range uncertainties are beam-direction-specific (18). However, beam-specific PTVs (bsPTVs) (19) are not available in our clinical treatment planning system for IMPT. Nevertheless, we used the PTV concept to manage delivery uncertainties for plans with a non-parallel-opposed beam arrangements (20).…”

Section: Methodsmentioning

confidence: 99%

Multifield Optimization Intensity Modulated Proton Therapy for Head and Neck Tumors: A Translation to Practice

Frank

Cox

Gillin

et al. 2014

International Journal of Radiation Oncology*Biology*Physics

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Summary The first fifteen consecutive patients treated with multi-field optimization intensity modulated proton therapy (MFO-IMPT) were able to complete treatment with no need for treatment breaks and no hospitalizations. Ten patients presented with SCC and 5 with ACC. There were no treatment-related deaths and with a median follow-up of 28 months, the overall clinical complete response rate was 93.3%. Early clinical outcomes warrant further investigation of proton therapy in the management of head and neck malignancies. Background We report the first clinical experience and toxicity of multi-field optimization (MFO) intensity-modulated proton therapy (IMPT) for patients with head and neck tumors. Methods Fifteen consecutive patients with head and neck cancer underwent MFO-IMPT with active scanning beam proton therapy. Patients with SCC had comprehensive treatment extending from the base of the skull to the clavicle. The dose for chemoradiation therapy and radiation therapy alone was 70 Gy and 66 Gy, respectively. The robustness of each treatment plan was also analyzed to evaluate sensitivity to uncertainties associated with variations in patient setup and the effect of uncertainties with proton beam range in patients. Proton beam energies during treatment ranged from 72.5 to 221.8 MeV. Spot sizes varied depending on the beam energy and depth of the target, and the scanning nozzle delivered the spot scanning treatment “spot-by-spot” and “layer-by-layer” Results Ten patients presented with squamous cell carcinoma (SCC) and 5 with adenoid cystic carcinoma (ACC). All 15 patients were able to complete treatment with MFO-IMPT with no need for treatment breaks and no hospitalizations. There were no treatment-related deaths and with a median follow-up of 28 months (range: 20-35), the overall clinical complete response rate was 93.3% (95%, confidence interval 68.1% to 99.8%). Xerostomia occurred in all 15 patients as follows; Grade 1 - ten patients, Grade 2 - four patients, and Grade 3 - one patient. Mucositis within the planning target volumes was seen during the treatment of all patients; Grade 1 - one patient, Grade 2 - eight patients, and Grade 3 - six patients. No patient experienced Grade 2 or higher anterior oral mucositis. Conclusions This is the first clinical report of MFO-IMPT for head and neck tumors. Early clinical outcomes are encouraging and warrant further investigation of proton therapy in prospective clinical trials.

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Section: Methodsmentioning

confidence: 99%

Multifield Optimization Intensity Modulated Proton Therapy for Head and Neck Tumors: A Translation to Practice

Frank

Cox

Gillin

et al. 2014

International Journal of Radiation Oncology*Biology*Physics

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135

120

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“…Since conventional geometric margins are not suitable for PT [Park et al, 2012b], margins based on range changes were used. Another trial comparing photon to proton therapy in NSCLC patients also used different PTV definitions to incorporate range changes [Roelofs et al, 2012].…”

Section: Range Margins and Motion Mitigationmentioning

confidence: 99%

In silico comparison of photons versus carbon ions in single fraction therapy of lung cancer

et al. 2016

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Stereotactic body image guided radiation therapy (SBRT) shows excellent results for the local control of early stage lung cancer. However, not all patients are eligible for SBRT, and advanced stage treatment is less successful and often associated with severe side effects. Scanned carbon ion therapy (PT) can deliver more conformal dose likely benefiting these patient groups.Therefore an in silico trial was conducted on early and advanced stage patients to identify potential advantages of PT. The patients were treated with SBRT at Champalimaud Center for the Unknown, Lisbon (Portugal). PT plans were simulated on 4DCTs, and rescanning was investigated for motion mitigation in 4D-dose calculations. A dedicated strategy for 4D intensity modulated particle therapy (IMPT) was developed and applied for advanced stage patients with multiple lesions. For clinically valid and reliable results the deformable image registrationnecessary for 4D-dose calculation -a quality assurance tool was developed and applied in the study.The results showed that target coverage was comparable in SBRT and PT, while PT delivered significantly lower doses to most critical structures, especially the heart, lungs, and esophagus.A highly complex case of advanced stage lung cancer could be treated in a single fraction of 24 Gy with PT, while SBRT could not deliver the full ablative dose treatment due to an excessive heart dose. The mean heart dose was reduced from 10 Gy to 0.8 Gy with PT for this specific patient.

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“…However, scanning beam proton therapy does not require such beam-specific hardware, therefore lacks the method of appropriately accounting for the uncertainties in order to provide adequate target coverage. Recently, Park et al 10 have demonstrated that beam specific planning target volume (bsPTV) could take into account of both setup and range uncertainties for scanning beam plans generated with single field optimization. 10 However, bsPTV is not applicable to the multifield optimized IMPT plans.…”

Section: Introductionmentioning

confidence: 99%

Effectiveness of robust optimization in intensity‐modulated proton therapy planning for head and neck cancers

et al. 2013

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Purpose: Intensity-modulated proton therapy (IMPT) is highly sensitive to uncertainties in beam range and patient setup. Conventionally, these uncertainties are dealt using geometrically expanded planning target volume (PTV). In this paper, the authors evaluated a robust optimization method that deals with the uncertainties directly during the spot weight optimization to ensure clinical target volume (CTV) coverage without using PTV. The authors compared the two methods for a population of head and neck (H&N) cancer patients. Methods: Two sets of IMPT plans were generated for 14 H&N cases, one being PTV-based conventionally optimized and the other CTV-based robustly optimized. For the PTV-based conventionally optimized plans, the uncertainties are accounted for by expanding CTV to PTV via margins and delivering the prescribed dose to PTV. For the CTV-based robustly optimized plans, spot weight optimization was guided to reduce the discrepancy in doses under extreme setup and range uncertainties directly, while delivering the prescribed dose to CTV rather than PTV. For each of these plans, the authors calculated dose distributions under various uncertainty settings. The root-mean-square dose (RMSD) for each voxel was computed and the area under the RMSD-volume histogram curves (AUC) was used to relatively compare plan robustness. Data derived from the dose volume histogram in the worst-case and nominal doses were used to evaluate the plan optimality. Then the plan evaluation metrics were averaged over the 14 cases and were compared with two-sided paired t tests. Results: CTV-based robust optimization led to more robust (i.e., smaller AUCs) plans for both targets and organs. Under the worst-case scenario and the nominal scenario, CTV-based robustly optimized plans showed better target coverage (i.e., greater D 95% ), improved dose homogeneity (i.e., smaller D 5% − D 95% ), and lower or equivalent dose to organs at risk. Conclusions: CTV-based robust optimization provided significantly more robust dose distributions to targets and organs than PTV-based conventional optimization in H&N using IMPT. Eliminating the use of PTV and planning directly based on CTV provided better or equivalent normal tissue sparing.

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A Beam-Specific Planning Target Volume (PTV) Design for Proton Therapy to Account for Setup and Range Uncertainties

Cited by 155 publications

References 20 publications

Multifield Optimization Intensity Modulated Proton Therapy for Head and Neck Tumors: A Translation to Practice

Multifield Optimization Intensity Modulated Proton Therapy for Head and Neck Tumors: A Translation to Practice

In silico comparison of photons versus carbon ions in single fraction therapy of lung cancer

Effectiveness of robust optimization in intensity‐modulated proton therapy planning for head and neck cancers

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