Significant tumor shift in patients treated with stereotactic radiosurgery for brain metastasis.

Introduction: Linac-based stereotactic radiosurgery (SRS) for brain metastases may be influenced by the time interval between treatment preparation and delivery, related to risk of anatomical changes. We studied tumor position shifts and its relations to peritumoral volume edema changes over time, as seen on MRI.

Methods: Twenty-six patients who underwent SRS for brain metastases in our institution were included.

Reproducibility of the MRI-defined spinal cord position in stereotactic radiotherapy for spinal oligometastases.

Purpose: To establish the reproducibility of the MRI-defined spinal cord position within the spinal canal.

Materials And Methods: We acquired T1- and T2-weighted MRI scans of 15 volunteers on spine levels C7, T8 or L2. The scan protocol was repeated several times for different postures and time intervals.

Dosimetric impact of post-operative seroma reduction during radiotherapy after breast-conserving surgery.

Purpose: Three boost radiotherapy (RT) techniques were compared to evaluate the dosimetric effect of seroma reduction during RT after breast-conserving surgery (BCS).

Materials And Methods: Twenty-one patients who developed seroma after BCS were included. Each patient underwent three CT scans: one week before RT (CT(-1)), in the third (CT(3)) and fifth (CT(5)) week of RT.

Multiinstitutional study on target volume delineation variation in breast radiotherapy in the presence of guidelines.

Purpose: This study aims to determine magnitude, causes and consequences of post-operative breast tumour target volume delineation variation among radiation oncologists in the presence of guidelines.

Materials And Methods: Excision cavities, CTVs and PTVs of eight breast cancer patients were delineated on CT scans by 13 Dutch radiation oncologists (observers) from 12 Dutch institutes participating in the international Young Boost Trial. Delineated volumes and conformity indices were determined.

Clinical applicability of cone-beam computed tomography in monitoring seroma volume change during breast irradiation.

Purpose: To determine whether cone-beam CT (CBCT) is effective in monitoring seroma reduction during breast irradiation when compared with conventional CT.

Patients And Methods: This study included 19 women with Stage T1-2 breast cancer treated with breast-conserving therapy. Each patient underwent two to four CT and multiple CBCT scans (mean, 8; range, 7-13 scans) at various time intervals during radiotherapy.

Clinical factors associated with seroma volume reduction in breast-Conserving Therapy for early-stage breast cancer: a multi-institutional analysis.

Purpose: To correlate clinical factors with seroma volume and reduction; and to determine whether cone-beam CT (CBCT) could be used clinically to monitor seroma reduction.

Patients And Methods: This investigation included 102 women from five institutions with stage T1-2 breast cancer treated with breast-conserving therapy. Two CT scans were acquired: the planning CT (CT1) and a second CT (CT2) during radiotherapy (RT).

Extracting global and local dynamics from the stochastics of rhythmic forearm movements.

The authors examined the dynamics governing rhythmic forearm movements that 9 participants performed under a variety of task constraints by using a generic, unbiased analysis technique for extracting the drift coefficients of Fokker-Planck equations from stochastic data. From those coefficients, they reconstructed and analyzed vector fields and phase portraits to identify characteristic, task-dependent kinematic and dynamical features. They first directly estimated the parameters of weakly nonlinear self-sustaining oscillators from the extracted drift coefficients.

Deterministic and stochastic features of rhythmic human movement.

The dynamics of rhythmic movement has both deterministic and stochastic features. We advocate a recently established analysis method that allows for an unbiased identification of both types of system components. The deterministic components are revealed in terms of drift coefficients and vector fields, while the stochastic components are assessed in terms of diffusion coefficients and ellipse fields.

Discrete and cyclical movements: unified dynamics or separate control?

In the literature on motor control, three theoretical perspectives on the relation between discrete and cyclical movements may be discerned: (a) cyclical movements are concatenated discrete movements; (b) discrete movements are a limiting case of cyclical movements, and (c) discrete and cyclical movements are motor primitives that may be combined but are irreducible to each other. To examine the tenability of these perspectives, 16 participants performed cyclical and discrete (flexion and extension) reaching movements of various amplitudes to differently sized targets. The kinematic properties of the recorded movements were analyzed and compared in detail.