Substantial Sparing of Organs at Risk with Modern Proton Therapy in Lung Cancer, but Altered Breathing Patterns Can Jeopardize Target Coverage.

Enhancing treatment of locally advanced non-small cell lung cancer (LA-NSCLC) by using pencil beam scanning proton therapy (PBS-PT) is attractive, but little knowledge exists on the effects of uncertainties occurring between the planning (Plan) and the start of treatment (Start). In this prospective simulation study, we investigated the clinical potential for PBS-PT under the influence of such uncertainties. Imaging with 4DCT at Plan and Start was carried out for 15 patients that received state-of-the-art intensity-modulated radiotherapy (IMRT).

Impact of RBE variations on risk estimates of temporal lobe necrosis in patients treated with intensity-modulated proton therapy for head and neck cancer.

Background: Temporal lobe necrosis (TLN) is a potential late effect after radiotherapy for skull base head and neck cancer (HNC). Several photon-derived dose constraints and normal tissue complication probability (NTCP) models have been proposed, however variation in relative biological effectiveness (RBE) may challenge the applicability of these dose constraints and models in proton therapy. The purpose of this study was therefore to investigate the influence of RBE variations on risk estimates of TLN after Intensity-Modulated Proton Therapy for HNC.

Mixed Effect Modeling of Dose and Linear Energy Transfer Correlations With Brain Image Changes After Intensity Modulated Proton Therapy for Skull Base Head and Neck Cancer.

Purpose: Intensity modulated proton therapy (IMPT) could yield high linear energy transfer (LET) in critical structures and increased biological effect. For head and neck cancers at the skull base this could potentially result in radiation-associated brain image change (RAIC). The purpose of the current study was to investigate voxel-wise dose and LET correlations with RAIC after IMPT.

Outcomes and patterns of radiation associated brain image changes after proton therapy for head and neck skull base cancers.

Background And Purpose: To characterize patterns and outcomes of brain MR image changes after proton therapy (PT) for skull base head and neck cancer (HNC).

Material And Methods: Post-treatment MRIs ≥6 months were reviewed for radiation-associated image changes (RAIC) in 127 patients. All patients had received at least a point dose of 40 Gy(RBE) to the brain.

Plan Selection in Proton Therapy of Locally Advanced Prostate Cancer with Simultaneous Treatment of Multiple Targets.

Purpose: Intensity modulated proton therapy (IMPT) of locally advanced prostate cancer can spare the bowel considerably compared with modern photon therapy, but simultaneous treatment of the prostate (p), seminal vesicles (sv), and lymph nodes is challenging owing to day-to-day organ motion and range uncertainties. Our purpose was, therefore, to generate a plan library for use in adaptive IMPT to mitigate these uncertainties.

Methods And Materials: We retrospectively included 27 patients with a series of computed tomography scans throughout their treatment representing day-to-day variation.

Imaging for Target Delineation and Treatment Planning in Radiation Oncology: Current and Emerging Techniques.

Imaging in radiation oncology has a wide range of applications. It is necessary not only for tumor staging and treatment response assessment after therapy but also for the treatment planning process, including definition of target and organs at risk, as well as treatment plan calculation. This article provides a comprehensive overview of the main imaging modalities currently used for target delineation and treatment planning and gives insight into new and promising techniques.

Exploration and application of phenomenological RBE models for proton therapy.

The relative biological effectiveness (RBE) of protons varies with multiple physical and biological factors. Phenomenological RBE models have been developed to include such factors in the estimation of a variable RBE, in contrast to the clinically applied constant RBE of 1.1.

The influence of inter-fractional anatomy variation on secondary cancer risk estimates following radiotherapy.

Purpose: In silico studies comparing estimated risks of radiation-induced secondary cancer (SC) are frequently performed in assessment of radiotherapy techniques. Since inter-patient anatomy variations can result in considerable differences in estimated risk we aimed to explore the influence of inter-fractional organ motion patterns on SC risk.

Methods: Volumetric modulated arc therapy (VMAT) and intensity-modulated proton therapy (IMPT) plans were generated on the planning CT (pCT) scans of eight prostate cancer patients.

Linear energy transfer distributions in the brainstem depending on tumour location in intensity-modulated proton therapy of paediatric cancer.

Background: For tumours near organs at risk, there is concern about unintended increase in biological dose from elevated linear energy transfer (LET) at the distal end of treatment fields. The objective of this study was therefore to investigate how different paediatric posterior fossa tumour locations impact LET and biological dose to the brainstem during intensity-modulated proton therapy (IMPT).

Material And Methods: Multiple IMPT plans were generated for four different simulated tumour locations relative to the brainstem for a five-year-old male patient.

Modelling of organ-specific radiation-induced secondary cancer risks following particle therapy.

Background And Purpose: Radiation-induced cancer is a serious late effect that may follow radiotherapy. A considerable uncertainty is associated with carcinogenesis from photon-based treatment, and even less established when including relative biological effectiveness (RBE) for particle therapy. The aim of this work was therefore to estimate and in particular explore relative risks (RR) of secondary cancer (SC) following particle therapy as applied in treatment of prostate cancer.

Estimated risk of radiation-induced cancer following paediatric cranio-spinal irradiation with electron, photon and proton therapy.

Background: Improvement in radiotherapy during the past decades has made the risk of developing a radiation-induced secondary cancer as a result of dose to normal tissue a highly relevant survivorship issue. Important factors expected to influence secondary cancer risk include dose level and dose heterogeneity, as well as gender and type of tissue irradiated. The elevated radio-sensitivity in children calls for models particularly tailored to paediatric cancer patients.