ABSTRACT
Objective. Respiration negatively affects the outcome of a radiation therapy treatment, with potentially severe effects especially in particle therapy (PT). If compensation strategies are not applied, accuracy cannot be achieved. To support the clinical practice based on 4D computed tomography (CT), 4D magnetic resonance imaging (MRI) acquisitions can be exploited. The purpose of this study was to validate a method for virtual 4DCT generation from 4DMRI data for lung cancers on a porcine lung phantom, and to apply it to lung cancer patients in PT.Approach. Deformable image registration was used to register each respiratory phase of the 4DMRI to a reference phase. Then, a static 3DCT was registered to this reference MR image set, and the virtual 4DCT was generated by warping the registered CT according to previously obtained deformation fields. The method was validated on a physical phantom for which a ground truth 4DCT was available and tested on lung tumor patients, treated with gated PT at end-exhale, by comparing the virtual 4DCT with a re-evaluation 4DCT. The geometric and dosimetric evaluation was performed for both proton and carbon ion treatment plans.Main results. The phantom validation exhibited a geometrical accuracy within the maximum resolution of the MRI and mean dose deviations, with respect to the prescription dose, up to 3.2% for targetD95%, with a mean gamma pass rate of 98%. For patients, the virtual and re-evaluation 4DCTs showed good correspondence, with errors on targetD95%up to 2% within the gating window. For one patient, dose variations up to 10% at end-exhale were observed due to relevant inter-fraction anatomo-pathological changes that occurred between the planning and re-evaluation CTs.Significance. Results obtained on phantom data showed that the virtual 4DCT method was accurate, allowing its application on patient data for testing within a clinical scenario.
Subject(s)
Four-Dimensional Computed Tomography , Lung Neoplasms , Animals , Swine , Four-Dimensional Computed Tomography/methods , Radiotherapy Planning, Computer-Assisted/methods , Lung Neoplasms/diagnostic imaging , Lung Neoplasms/radiotherapy , Respiration , Radiometry/methodsABSTRACT
Hadrontherapy is a form of radiation therapy (RT) that relies on heavy particles, such as proton, heavy ions, or neutrons, to enhance anti-tumoral efficacy based on their specific dosimetric and radio-biological properties. Neutrons are characterized by specific radiobiological properties that might deserve greater consideration, including the high linear energy transfer and the low oxygen enhancement ratio. Neutron brachytherapy, relying on interstitial or intracavitary neutron sources, has been developed since the 1950s using Californium-252 (252Cf) as a mixed emitter of fission fast neutrons and γ-photos. However, the place of NBT in the era of modern radiation therapy is yet to be precisely defined. In this systematic review, we aim to provide an up-to-date analysis of current experience and clinical evidence of NBT in the XXI th century, by answering the following clinical questions: How is NBT currently delivered? What are the current efficacy data and tolerance profiles of NBT?
Subject(s)
Brachytherapy , Neoplasms , Humans , Neutrons , Neoplasms/radiotherapy , Radiometry , Radiotherapy DosageABSTRACT
Re-irradiation of pelvic recurrent gynecological cancer is a challenge due to the proximity of high-radiation-sensitive organs, such as the bowel and the urinary tract. Hadrontherapy for re-irradiation emerges as a safe and effective treatment with a mild rate of morbidity of surrounding normal tissue. To improve the dose to the tumor, a prophylactic displacement of organs at risk is needed, and a multidisciplinary approach is recommended. In this technical note, we report a surgical technique of omentum spacer placement for patients enrolled for carbon ion radiotherapy as re-irradiation for recurrent gynecological tumors.
Subject(s)
Heavy Ion Radiotherapy , Pelvic Neoplasms , Re-Irradiation , Heavy Ion Radiotherapy/methods , Humans , Neoplasm Recurrence, Local/pathology , Neoplasm Recurrence, Local/radiotherapy , Omentum/pathology , Radiotherapy Dosage , Re-Irradiation/methodsABSTRACT
AIMS: To report oncologic and functional outcomes in terms of tumor control and toxicity of carbon ion radiotherapy (CIRT) in reirradiation setting for recurrent salivary gland tumors at CNAO. METHODS: From November 2013 to September 2016, 51 consecutive patients with inoperable recurrent salivary gland tumors were retreated with CIRT in the frame of the phase II protocol CNAO S14/2012C for recurrent head and neck tumors. RESULTS: Majority of pts (74.5%) had adenoid cystic carcinoma, mainly rcT4a (51%) and rcT4b (37%). Median dose of prior photon based radiotherapy was 60 Gy. Median dose of CIRT was 60 Gy [RBE] at a mean of 3 Gy [RBE] per fraction. During reirradiation, 19 patients (37.3%) experienced grade G1 toxicity, 19 pts (37.3%) had G2 and 2 pts (3.9%) had G3. Median follow up time was 19 months. Twenty one (41.2%) patients had stable disease and 30 (58.8%) tumor progression at the time of last follow up. Furthermore, 9 (18%) patients had G1 late toxicity, 19 (37%) had G2 and 9 (17. 5%) had G3. Using the Kaplan Meier method, progression free survival (actuarial) at one and two years were 71.7% and 52.2% respectively. Estimated overall survival (actuarial) at one and two years were 90.2% and 64%, respectively. CONCLUSIONS: CIRT is a good option for retreatment of inoperable recurrent salivary gland tumors with acceptable rates of acute and late toxicity. Longer follow up time is needed to assess the effectiveness of CIRT in reirradiation setting of salivary gland tumors.