Evaluation of the setup margins for cone beam computed tomography-guided cranial radiosurgery: A phantom study.

The aim of this study is to evaluate the setup margins from the clinical target volume (CTV) to planning target volume (PTV) for cranial stereotactic radiosurgery (SRS) treatments guided by cone beam computed tomography (CBCT). We designed an end-to-end (E2E) test using a skull phantom with an embedded 6mm tungsten ball (target). A noncoplanar plan was computed (E2E plan) to irradiate the target.

Treatment precision of image-guided liver SBRT using implanted fiducial markers depends on marker-tumour distance.

The purpose of this study is to assess the accuracy of day-to-day predictions of liver tumour position using implanted gold markers as surrogates and to compare the method with alternative set-up strategies, i.e. no correction, vertebrae and 3D diaphragm-based set-up.

Potentials and limitations of guiding liver stereotactic body radiation therapy set-up on liver-implanted fiducial markers.

Purpose: We investigated the potentials and limitations of guiding liver stereotactic body radiation therapy (SBRT) set-up on liver-implanted fiducial markers.

Methods And Materials: Twelve patients undergoing compression-supported SBRT in a stereotactic body frame received fluoroscopy at treatment preparation and before each treatment fraction. In fluoroscopic videos we localized the markers and diaphragm tip at expiration and the spine (measurements on free-breathing and abdominal compression).

Stereotactic body radiation therapy for colorectal liver metastases.

Background: Stereotactic body radiation therapy (SBRT) is a treatment option for colorectal liver metastases. Local control, patient survival and toxicity were assessed in an experience of SBRT for colorectal liver metastases.

Methods: SBRT was delivered with curative intent to 20 consecutively treated patients with colorectal hepatic metastases who were candidates for neither resection nor radiofrequency ablation (RFA).

Stereotactic body radiation therapy for liver tumors: impact of daily setup corrections and day-to-day anatomic variations on dose in target and organs at risk.

Purpose: To assess day-to-day differences between planned and delivered target volume (TV) and organ-at-risk (OAR) dose distributions in liver stereotactic body radiation therapy (SBRT), and to investigate the dosimetric impact of setup corrections.

Methods And Materials: For 14 patients previously treated with SBRT, the planning CT scan and three treatment scans (one for each fraction) were included in this study. For each treatment scan, two dose distributions were calculated: one using the planned setup for the body frame (no correction), and one using the clinically applied (corrected) setup derived from measured tumor displacements.

Automated non-coplanar beam direction optimization improves IMRT in SBRT of liver metastasis.

Purpose: To investigate whether automatically optimized coplanar, or non-coplanar beam setups improve intensity modulated radiotherapy (IMRT) treatment plans for stereotactic body radiotherapy (SBRT) of liver tumors, compared to a reference equi-angular IMRT plan.

Methods: For a group of 13 liver patients, an in-house developed beam selection algorithm (Cycle) was used for generation of 3D-CRT plans with either optimized coplanar-, or non-coplanar beam setups. These 10 field, coplanar and non-coplanar setups, and an 11 field, equi-angular coplanar reference setup were then used as input for generation of IMRT plans.

Reduction of respiratory liver tumor motion by abdominal compression in stereotactic body frame, analyzed by tracking fiducial markers implanted in liver.

Purpose: To investigate in a three-dimensional framework the effectiveness and reproducibility of reducing the respiratory motion of liver tumors using abdominal compression in a stereotactic body frame.

Methods And Materials: A total of 12 patients with liver tumors, who were treated with stereotactic body radiotherapy, were included in this study. These patients had three gold fiducial markers implanted in the healthy liver tissue surrounding the tumor.

Simultaneous tumour dose escalation and liver sparing in Stereotactic Body Radiation Therapy (SBRT) for liver tumours due to CTV-to-PTV margin reduction.

Purpose: To quantify potential benefits of CTV-to-PTV margin reduction for SBRT of liver tumours, as allowed by enhanced treatment precision.

Materials And Methods: For 14 patients plans were generated for the clinical margin and for 3 tighter margins. An in-house developed algorithm was used to optimise beam directions, shapes, and weights for generation of the plan with the highest isocenter dose (D(iso)), while keeping the minimum PTV dose at least 65%xD(iso) and strictly adhering to all imposed hard OAR constraints.

PTV dose prescription strategies for SBRT of metastatic liver tumours.

Purpose: Recently we have demonstrated that our in-house developed algorithm for automated plan generation for fully non-coplanar SBRT of liver patients (designated Cycle) yields plans that are superior to conventionally generated plans of experienced dosimetrists. Here we use Cycle in the comparison of plans with prescription isodoses of 65% or 80% of the isocentre dose.

Methods: Plans were generated using CT-data of 15 previously treated patients.

Target coverage in image-guided stereotactic body radiotherapy of liver tumors.

Purpose: To determine the effect of image-guided procedures (with computed tomography [CT] and electronic portal images before each treatment fraction) on target coverage in stereotactic body radiotherapy for liver patients using a stereotactic body frame (SBF) and abdominal compression. CT guidance was used to correct for day-to-day variations in the tumor's mean position in the SBF.

Methods And Materials: By retrospectively evaluating 57 treatment sessions, tumor coverage, as obtained with the clinically applied CT-guided protocol, was compared with that of alternative procedures.

Stereotactic body radiation therapy for primary and metastatic liver tumors: A single institution phase i-ii study.

The feasibility, toxicity and tumor response of stereotactic body radiation therapy (SBRT) for treatment of primary and metastastic liver tumors was investigated. From October 2002 until June 2006, 25 patients not suitable for other local treatments were entered in the study. In total 45 lesions were treated, 34 metastases and 11 hepatocellular carcinoma (HCC).

Intake of polyunsaturated fatty acids and vitamin E reduces the risk of developing amyotrophic lateral sclerosis.

Background: To assess whether the premorbid dietary intake of fatty acids, cholesterol, glutamate or antioxidants was associated with the risk of developing amyotrophic lateral sclerosis (ALS).

Methods: Patients referred to our clinic during 2001-2002, who had definite, probable or possible ALS according to El Escorial criteria, without a familial history of ALS, were asked to participate in a case-control study (132 patients and 220 healthy controls). A food-frequency questionnaire was used to assess dietary intake for the nutrients of interest.