The probability of correct target dosage: dose-population histograms for deriving treatment margins in radiotherapy.

Purpose: To provide an analytical description of the effect of random and systematic geometrical deviations on the target dose in radiotherapy and to derive margin rules.

Methods And Materials: The cumulative dose distribution delivered to the clinical target volume (CTV) is expressed analytically. Geometrical deviations are separated into treatment execution (random) and treatment preparation (systematic) variations.

A treatment planning method to correct dose distributions distorted by setup verification fields.

Purpose: Portal images of conformal treatment fields are often not suitable for setup verification purposes because they contain insufficient bony structures. Therefore, additional rectangular fields are frequently applied for setup verification purposes. It is the aim of this study to reduce the dose distortions induced by these extra fields by appropriately adjusting the beam weights and wedge angles of the treatment fields.

3-D portal image analysis in clinical practice: an evaluation of 2-D and 3-D analysis techniques as applied to 30 prostate cancer patients.

Purpose: To investigate the clinical importance and feasibility of a 3-D portal image analysis method in comparison with a standard 2-D portal image analysis method for pelvic irradiation techniques.

Methods And Materials: In this study, images of 30 patients who were treated for prostate cancer were used. A total of 837 imaged fields were analyzed by a single technologist, using automatic 2-D and 3-D techniques independently.

The role of mdr1a P-glycoprotein in the biliary and intestinal secretion of doxorubicin and vinblastine in mice.

Drug-transporting P-glycoproteins are abundantly present in the liver and the intestinal wall. We have now investigated their role in the biliary and intestinal secretion of the anticancer drugs doxorubicin (unlabeled: 5 mg/kg) and vinblastine ((3)H-labeled: 1 mg/kg) i.v.

In vivo dosimetry during conformal radiotherapy: requirements for and findings of a routine procedure.

Purpose: Conformal radiotherapy requires accurate knowledge of the actual dose delivered to a patient. The impact of routine in vivo dosimetry, including its special requirements, clinical findings and resources, has been analysed for three conformal treatment techniques to evaluate its usefulness in daily clinical practice.

Materials And Methods: Based on pilot studies, routine in vivo dosimetry quality control (QC) protocols were implemented in the clinic.

Dose-wall histograms and normalized dose-surface histograms for the rectum: a new method to analyze the dose distribution over the rectum in conformal radiotherapy.

Purpose: To develop an accurate method to generate a dose-volume histogram (DVH) of the rectum wall, solely based on the outer contours of the rectum wall.

Methods And Materials: A mathematical model for the rectum wall is developed, incorporating the stretching of the rectum wall due to variable rectal filling and neighboring structures. The model is based on the assumption that the amount of intersected rectum wall tissue normal to the central axis of the rectum is constant.

Comparison of prostate cancer treatment in two institutions: a quality control study.

Purpose: To minimize differences in the treatment planning procedure between two institutions within the context of a radiotherapy prostate cancer trial.

Patients And Methods: Twenty-two patients with N0 M0 prostate cancer underwent a computed tomography (CT) scan for radiotherapy treatment planning. For all patients, the tumor and organs at risk were delineated, and a treatment plan was generated for a three-field technique giving a dose of 78 Gy to the target volume.

Cremophor EL causes (pseudo-) non-linear pharmacokinetics of paclitaxel in patients.

The non-linear plasma pharmacokinetics of paclitaxel in patients has been well established, however, the exact underlying mechanism remains to be elucidated. We have previously shown that the non-linear plasma pharmacokinetics of paclitaxel in mice results from Cremophor EL. To investigate whether Cremophor EL also plays a role in the non-linear pharmacokinetics of paclitaxel in patients, we have established its pharmacokinetics in patients receiving paclitaxel by 3-, 24- or 96-h intravenous infusion.

High-speed digital imaging of neoglottic vibration after total laryngectomy.

Objectives: To establish the applicability of digital high-speed imaging in studying neoglottic mucosal vibration after total laryngectomy and to perform a structured evaluation of the recordings using a standardized assessment form to gain insight about the anatomical and morphologic characteristics of the neoglottis.

Design: Evaluation of a new clinical tool and description of clinical disorders in a patient survey.

Setting: The Netherlands Cancer Institute, Amsterdam.

A general methodology for three-dimensional analysis of variation in target volume delineation.

A generic method for three-dimensional (3-D) evaluation of target volume delineation in multiple imaging modalities is presented. The evaluation includes geometrical and statistical methods to estimate observer differences and variability in defining the Gross Tumor Volume (GTV) in relation to the diagnostic CT and MRI modalities. The geometrical method is based on mapping the 3-D shape of the target volume to a scalar representation, thus enabling a one-dimensional statistical analysis.

TPA and CA 15.3 measurements for breast cancer monitoring in a routine setting.

TPA and CA 15.3 concentrations were routinely determined in serum of patients treated for breast cancer during a 15-month period. ROC curves did not show differences in the ability to differentiate between NED and PD on the basis of matching tumor marker values.

The development of a prognostic score for patients with parotid carcinoma.

Background: Understanding of prognostic factors in parotid carcinoma has grown considerably. In particular, clinical tumor staging and histologic classification have been found to be prognostically important. Univariate and multivariate analyses have indicated that other variables, such as age, pain, skin invasion, and facial nerve impairment, are important predictors as well.

Lectin-induced retardation of subcellular organelles during preparative density gradient electrophoresis: selective purification of plasma membranes.

Plasma membranes (PM) are difficult to separate by conventional means from other cellular compartments. Using a density gradient electrophoresis (DGE) apparatus (7 cm, x 2.2 cm), mammalian subcellular organelles were separated from a total postnuclear supernatant.

Phase II trial of topically applied miltefosine solution in patients with skin-metastasized breast cancer.

Skin deposits from breast cancer can present serious therapeutic problems, especially when resistant to conventional therapy. Topical application of a cytotoxic drug may represent an attractive new treatment modality devoid of major systemic toxicity. Miltefosine was selected because of its efficacy in breast cancer models.

Beam intensity modulation to reduce the field sizes for conformal irradiation of lung tumors: a dosimetric study.

Purpose: In conformal radiotherapy of lung tumors, penumbra broadening in lung tissue necessitates the use of larger field sizes to achieve the same target coverage as in a homogeneous environment. In an idealized model configuration, some fundamental aspects of field size reduction were investigated, both for the static situation and for a moving tumor, while maintaining the dose homogeneity in the target volume by employing a simple beam-intensity modulation technique.

Methods And Materials: An inhomogeneous phantom, consisting of polystyrene, cork, and polystyrene layers, with a 6 x 6 x 6 cm3 polystyrene cube inside the cork representing the tumor, was used to simulate a lung cancer treatment.

Muscle-invasive bladder cancer treated with external beam radiotherapy: pretreatment prognostic factors and the predictive value of cystoscopic re-evaluation during treatment.

Purpose: To determine the relationship between tumour and patient characteristics and local control and survival for patients with T2 and T3 bladder cancer treated with radical external beam radiotherapy and to evaluate the predictive value of cystoscopic response evaluation during radiation on final outcome.

Materials And Methods: Records from 379 patients with non-metastasized T2 or T3 transitional cell carcinoma of the bladder were reviewed. All patient received external beam radiotherapy at The Netherlands Cancer Institute during the period from 1977 to 1990.

Definition of the prostate in CT and MRI: a multi-observer study.

Purpose: To determine, in three-dimensions, the difference between prostate delineation in magnetic resonance (MR) and computer tomography (CT) images for radiotherapy treatment planning.

Patients And Methods: Three radiation oncologists, considered experts in the field, outlined the prostate without seminal vesicles both on CT, and axial, coronal, and sagittal MR images for 18 patients. To compare the resulting delineated prostates, the CT and MR scans were matched in three-dimensions using chamfer matching on bony structures.

High-performance liquid chromatographic bio-analysis of PSC 833 in human and murine plasma.

We have developed a rapid, sensitive and selective method for the determination of the cyclosporin analog PSC 833 in human and mouse plasma using cyclosporin A as internal standard. The assay uses liquid-liquid extraction with diethyl ether for sample clean-up followed by reversed-phase high-performance liquid chromatography with UV detection at 210 nm. Good peak shapes were obtained using a NovaPak Phenyl column operating at 72 degrees C.

Radiation-induced apoptosis--the ceramide-SAPK signaling pathway and clinical aspects.

Apoptosis, or programmed cell death is an important regulatory mechanism that is involved in a variety of homeostatic processes. Decreased cellular sensitivity or inappropriate responses to apoptotic stimuli may be important factors in tumorigenesis and resistance to anticancer treatments. It is generally accepted that all mammalian cells constitutively express the biochemical machinery to execute apoptosis.

Muscle-invasive bladder cancer treated with external beam radiation: influence of total dose, overall treatment time, and treatment interruption on local control.

Purpose: To evaluate and eventually quantify a possible influence of tumor proliferation during the external radiation course on local control in muscle invasive bladder cancer.

Methods And Materials: The influence of total dose, overall treatment time, and treatment interruption has retrospectively been analyzed in a series of 379 patients with nonmetastasized, muscle-invasive transitional cell carcinoma of the urinary bladder. All patients received external beam radiotherapy at the Netherlands Cancer Institute between 1977 and 1990.

Automatic registration of pelvic computed tomography data and magnetic resonance scans including a full circle method for quantitative accuracy evaluation.

The purpose of this study is to develop a method for registration of CT and MR scans of the pelvis with minimal user interaction and to obtain a means for objective quantification of the registration accuracy of clinical data without markers. CT scans were registered with proton density MR scans using chamfer matching on automatically segmented bone. A fixed threshold was used to segment CT, while morphological filters were used to segment MR.

The impact of treatment time and smoking on local control and complications in T1 glottic cancer.

Purpose: To define the optimal treatment regimen, patients with T1N0M0 glottic larynx carcinoma were treated with six different radiotherapy (RT) schedules. To assess the influence of patient characteristics, complication rates, and to evaluate the overall larynx preservation.

Methods And Materials: Out of a consecutive series of 383 patients treated for T1N0M0 glottic larynx carcinoma between 1965 and 1992, 352 evaluable patients were treated with six different "standard" fractionation schedules: 65 Gy (20 x 3.

Radiation pneumonitis as a function of mean lung dose: an analysis of pooled data of 540 patients.

Purpose: To determine the relation between the incidence of radiation pneumonitis and the three-dimensional dose distribution in the lung.

Methods And Materials: In five institutions, the incidence of radiation pneumonitis was evaluated in 540 patients. The patients were divided into two groups: a Lung group, consisting of 399 patients with lung cancer and 1 esophagus cancer patient and a Lymph.

First clinical tests using a liquid-filled electronic portal imaging device and a convolution model for the verification of the midplane dose.

Background And Purpose: Recently, algorithms have been developed to derive the patient dose from portal dose measurements using a liquid-filled electronic portal imaging device. These algorithms have already been validated for several phantom geometries irradiated under clinical conditions. It is the aim of the present study to investigate the applicability of a liquid-filled electronic portal imaging device in combination with these algorithms for two-dimensional midplane dose verification in clinical practice.

The luminescence immunoassay S-100: a sensitive test to measure circulating S-100B: its prognostic value in malignant melanoma.

In this study we measured S-100B using a recently developed luminometric immunoassay with a detection limit of 0.02 microg l(-1). By measuring serum S-100B concentrations in 58 apparently healthy individuals a reference value of 0.