Individual lymph node position variation for rectal cancer patients treated with long course chemoradiotherapy.

Background And Purpose: Delivery of high precision radiotherapy lymph node boosts requires detailed information on the interfraction positional variation of individual lymph nodes. In this study we characterized interfraction positional shifts of suspected malignant lymph nodes for rectal cancer patients receiving long course radiotherapy. Furthermore, we investigated parameters which could affect the magnitude of the position variation.

Treatment planning for patients with low rectal cancer in a multicenter prospective organ preservation study.

Background: Non-surgical management of rectal cancer relies on (chemo)radiotherapy as the definitive treatment modality. This study reports and evaluates the clinical high dose radiotherapy treatment plans delivered to patients with low resectable rectal cancer in a Danish multicenter trial.

Methods: The Danish prospective multicenter phase II Watchful Waiting 2 trial (NCT02438839) investigated definitive chemoradiation for non-surgical management of low rectal cancer.

Consistency in contouring of organs at risk by artificial intelligence vs oncologists in head and neck cancer patients.

Background: In the Danish Head and Neck Cancer Group (DAHANCA) 35 trial, patients are selected for proton treatment based on simulated reductions of Normal Tissue Complication Probability (NTCP) for proton compared to photon treatment at the referring departments. After inclusion in the trial, immobilization, scanning, contouring and planning are repeated at the national proton centre. The new contours could result in reduced expected NTCP gain of the proton plan, resulting in a loss of validity in the selection process.

Evaluation of decentralised model-based selection of head and neck cancer patients for a proton treatment study. DAHANCA 35.

Introduction: Proton treatment can potentially spare patients with H&N cancer for substantial treatment-related toxicities. The current study investigated the reproducibility of a decentralised model-based selection of patients for a proton treatment study when the selection plans were compared to the clinical treatment plans performed at the proton centre.

Methods: Sixty-three patients were selected for proton treatment in the six Danish Head and Neck Cancer (DAHANCA) centres.

Target coverage and local recurrences after radiotherapy for sinonasal cancer in Denmark 2008-2015. A DAHANCA study.

Purpose: The study aimed to investigate the pattern of failure and describe compromises in the definition and coverage of the target for patients treated with curatively intended radiotherapy (RT) for sinonasal cancer (SNC).

Methods And Material: Patients treated with curatively intended RT in 2008-2015 in Denmark for SNC were eligible for the retrospective cohort study. Information regarding diagnosis and treatment was retrieved from the national database of the Danish Head and Neck Cancer Group (DAHANCA).

High-dose thoracic radiation therapy for non-small cell lung cancer: a novel grading scale of radiation-induced lung injury for symptomatic radiation pneumonitis.

Background: Symptomatic radiation pneumonitis (RP) may be a serious complication after thoracic radiation therapy (RT) for non-small cell lung cancer (NSCLC). This prospective observational study sought to evaluate the utility of a novel radiation-induced lung injury (RILI) grading scale (RGS) for the prediction of RP.

Materials And Methods: Data of 41 patients with NSCLC treated with thoracic RT of 60-66 Gy were analysed.

A new method to validate thoracic CT-CT deformable image registration using auto-segmented 3D anatomical landmarks.

Background: Deformable image registrations are prone to errors in aligning reliable anatomically features. Consequently, identification of registration inaccuracies is important. Particularly thoracic three-dimensional (3D) computed tomography (CT)-CT image registration is challenging due to lack of contrast in lung tissue.

Potential position errors using fiducial markers for gated image guided radiotherapy.

Background: Fiducials can be used as surrogate for target position during radiotherapy. However, fiducial motion could lead to potential position errors when using fiducials in four-dimensional computed tomography (4DCT) treatment planning and for gated image guided radiotherapy (IGRT).

Material And Methods: One gold marker (GM) and 5, 10 and 15 mm nickel-titanium (NiTi) stents were inserted in a moving phantom for the purpose of fiducial detection in 4DCT and gated IGRT.

A new lung stent tested as fiducial marker in a porcine model.

Introduction: The aim of the present study was to test the feasibility of a Nickel-Titanium (Ni-Ti) stent technique (Memocore™) in a porcine model. The stent is intended as a new fiducial for gated image guided radiotherapy in the lung. The study included test of an improved insertion system and respiratory gated treatments with this new technique.

Megavoltage image-based dynamic multileaf collimator tracking of a NiTi stent in porcine lungs on a linear accelerator.

Purpose: To investigate the accuracy and potential limitations of MV image-based dynamic multileaf collimator (DMLC) tracking in a porcine model on a linear accelerator.

Methods And Materials: A thermo-expandable NiTi stent designed for kilovoltage (kV) X-ray visualization of lung lesions was inserted into the bronchia of three anaesthetized Göttingen minipigs. A four-dimensional computed tomography scan was used for planning a five-field conformal treatment with circular multileaf collimator (MLC) apertures.

A phantom study of dose compensation behind hip prosthesis using portal dosimetry and dynamic MLC.

Background And Purpose: A dose compensation method is presented for patients with hip prosthesis based on Dynamic Multi Leaves Collimator (DMLC) planning. Calculations are done from an exit Portal Dose Image (PDI) from 6 MV Photon beam using an Electronic Portal Imaging Device (EPID) from Varian. Four different hip prostheses are used for this work.