The influence of a dietary protocol on cone beam CT-guided radiotherapy for prostate cancer patients.

Purpose: To evaluate the influence of a dietary protocol on cone beam computed tomography (CBCT) image quality, which is an indirect indicator for short-term (intrafraction) prostate motion, and on interfraction motion. Image quality is affected by motion (e.g.

Comparison of different strategies to use four-dimensional computed tomography in treatment planning for lung cancer patients.

Purpose: To discuss planning target volumes (PTVs) based on internal target volume (PTVITV), exhale-gated radiotherapy (PTVGating), and a new proposed midposition (PTVMidP; time-weighted mean tumor position) and compare them with the conventional free-breathing CT scan PTV (PTVConv).

Methods And Materials: Respiratory motion induces systematic and random geometric uncertainties. Their contribution to the clinical target volume (CTV)-to-PTV margins differs for each PTV approach.

3D in vivo dose verification of entire hypo-fractionated IMRT treatments using an EPID and cone-beam CT.

As radiotherapy becomes more complicated, dose and geometry verification become more necessary. The aim of this study was to use back-projected EPID-based 3D in vivo dosimetry and cone-beam CT (CBCT) to obtain a complete account of the entire treatment for a select patient group. Nine hypo-fractionated rectum IMRT patient plans were investigated.

99mTc-HYNIC-rh-annexin-V scintigraphy: visual and quantitative evaluation of early treatment-induced apoptosis to predict treatment outcome.

Aim: To determine the reliability of visual analysis of 99mTc-HYNIC-rh-annexin-V tumour uptake (ATU) compared to quantitative tracer uptake evaluation.

Methods: Thirty-eight patients (22 male, 16 female, mean age 57) with histologically proved lymphoma (n=31), non-small cell lung cancer (NSCLC) (n=4) and head and neck squamous cell carcinoma (H&NSCC) (n=3) were examined. 99mTc-HYNIC-rh-annexin-V scintigraphy (TAS) was acquired before and within 2 days after the start of anti-cancer treatment.

Variability of four-dimensional computed tomography patient models.

Purpose: To quantify the interfractional variability in lung tumor trajectory and mean position during the course of radiation therapy.

Methods And Materials: Repeat four-dimensional (4D) cone-beam computed tomography (CBCT) scans (median, nine scans/patient) routinely acquired during the course of treatment were analyzed for 56 patients with lung cancer. Tumor motion was assessed by using local rigid registration of a region of interest in the 3D planning CT to each phase in the 4D CBCT.

99mTc Hynic-rh-Annexin V scintigraphy for in vivo imaging of apoptosis in patients with head and neck cancer treated with chemoradiotherapy.

Purpose: The purpose of this study was to determine the value of (99m)Tc Hynic-rh-Annexin-V-Scintigraphy (TAVS), a non-invasive in vivo technique to demonstrate apoptosis in patients with head and neck squamous cell carcinoma.

Methods: TAVS were performed before and within 48 h after the first course of cisplatin-based chemoradiation. Radiation dose given to the tumour at the time of post-treatment TAVS was 6-8 Gy.

Impact of anatomical location on value of CT-PET co-registration for delineation of lung tumors.

Purpose: To derive guidelines for the need to use positron emission tomography (PET) for delineation of the primary tumor (PT) according to its anatomical location in the lung.

Methods And Materials: In 22 patients with non-small-cell lung cancer, thoracic X-ray computed tomography (CT) and PET were performed. Eleven radiation oncologists delineated the PT on the CT and on the CT-PET registered scans.

IMRT optimization including random and systematic geometric errors based on the expectation of TCP and NTCP.

The purpose of this work was the development of a probabilistic planning method with biological cost functions that does not require the definition of margins. Geometrical uncertainties were integrated in tumor control probability (TCP) and normal tissue complication probability (NTCP) objective functions for inverse planning. For efficiency reasons random errors were included by blurring the dose distribution and systematic errors by shifting structures with respect to the dose.

Strategy for online correction of rotational organ motion for intensity-modulated radiotherapy of prostate cancer.

Purpose: To develop and evaluate a correction strategy for prostate rotation using gantry and collimator angle adjustments.

Methods And Materials: Gantry and collimator angle adjustments were used to correct for prostate rotation without rotating the table. A formula to partially correct for left-right (LR) rotations was derived through geometric analysis of rotation-induced clinical target volume (CTV) beam's-eye-view shape changes.

Different styles of image-guided radiotherapy.

To account for geometric uncertainties during radiotherapy, safety margins are applied. In many cases, these margins overlap organs at risk, thereby limiting dose escalation. The aim of image-guided radiotherapy is to improve the accuracy by imaging tumors and critical structures on the machine just before irradiation.

Dental students' attitude towards anti-smoking programmes: a study in Flanders, Belgium.

Objective: The aim of the study was to assess the dental students' attitude towards tobacco cessation counselling in the dental setting and to explore the influence of knowledge, belief in effectiveness, smoking status, gender and curriculum.

Material And Methods: The study group consisted of all undergraduate students from the 2002-2003 classes of the Ghent University (n = 96). A validated questionnaire was administered to all students involving four different sections: demographic characteristics, attitude related to tobacco cessation programmes in the dental setting, belief in their effectiveness and knowledge concerning tobacco health effects.

A fast algorithm for gamma evaluation in 3D.

The gamma-evaluation method is a tool by which dose distributions can be compared in a quantitative manner combining dose-difference and distance-to-agreement criteria. Since its introduction, the gamma evaluation has been used in many studies and is on the verge of becoming the preferred dose distribution comparison method, particularly for intensity-modulated radiation therapy (IMRT) verification. One major disadvantage, however, is its long computation time, which especially applies to the comparison of three-dimensional (3D) dose distributions.

Three-dimensional heart dose reconstruction to estimate normal tissue complication probability after breast irradiation using portal dosimetry.

Irradiation of the heart is one of the major concerns during radiotherapy of breast cancer. Three-dimensional (3D) treatment planning would therefore be useful but cannot always be performed for left-sided breast treatments, because CT data may not be available. However, even if 3D dose calculations are available and an estimate of the normal tissue damage can be made, uncertainties in patient positioning may significantly influence the heart dose during treatment.

Short-term displacement and reproducibility of the breast and nodal targets under active breathing control.

Purpose: The short-term displacement and reproducibility of the breast or chest wall, and the internal mammary (IM), infraclavicular (ICV), and supraclavicular (SCV) nodal regions have been assessed as a function of breath-hold state using an active breathing control (ABC) device for patients receiving loco-regional breast radiation therapy.

Methods And Materials: Ten patients underwent computed tomographic scanning using an ABC device at breath-hold states of end-exhale and 20%, 40%, 60%, and 80% of vital capacity (VC). Patients underwent scanning before treatment and at one third and two thirds of the way through treatment.

Kilo-voltage cone-beam computed tomography setup measurements for lung cancer patients; first clinical results and comparison with electronic portal-imaging device.

Purpose: Kilovoltage cone-beam computed tomography (CBCT) has been developed to provide accurate soft-tissue and bony setup information. We evaluated clinical CBCT setup data and compared CBCT measurements with electronic portal imaging device (EPID) images for lung cancer patients.

Methods And Materials: The setup error for CBCT scans at the treatment unit relative to the planning CT was measured for 62 patients (524 scans).

Replacing pretreatment verification with in vivo EPID dosimetry for prostate IMRT.

Purpose: To investigate the feasibility of replacing pretreatment verification with in vivo electronic portal imaging device (EPID) dosimetry for prostate intensity-modulated radiotherapy (IMRT).

Methods And Materials: Dose distributions were reconstructed from EPID images, inside a phantom (pretreatment) or the patient (five fractions in vivo) for 75 IMRT prostate plans. Planned and EPID dose values were compared at the isocenter and in two dimensions using the gamma index (3%/3 mm).

Retrospective attenuation correction of PET data for radiotherapy planning using a free breathing CT.

Purpose: To evaluate the image quality of retrospectively attenuation corrected Positron Emission Tomography (PET) scans used for gross tumor volume (GTV) delineation in lung cancer patients.

Materials And Methods: Data of 13 lymph node positive lung cancer patients were acquired on separate CT and PET scanners under free breathing conditions (for radiotherapy planning). First we determined a protocol for CT/PET registration.

An adaptive off-line procedure for radiotherapy of prostate cancer.

Purpose: To determine the planning target volume (PTV) margin for an adaptive radiotherapy procedure that uses five computed tomography (CT) scans to calculate an average prostate position and rectum shape. To evaluate alternative methods to determine an average rectum based on a single delineation.

Methods And Materials: Repeat CT scans (8-13) of 19 patients were used.

Clinical experience with EPID dosimetry for prostate IMRT pre-treatment dose verification.

The aim of this study was to demonstrate how dosimetry with an amorphous silicon electronic portal imaging device (a-Si EPID) replaced film and ionization chamber measurements for routine pre-treatment dosimetry in our clinic. Furthermore, we described how EPID dosimetry was used to solve a clinical problem. IMRT prostate plans were delivered to a homogeneous slab phantom.

The management of respiratory motion in radiation oncology report of AAPM Task Group 76.

This document is the report of a task group of the AAPM and has been prepared primarily to advise medical physicists involved in the external-beam radiation therapy of patients with thoracic, abdominal, and pelvic tumors affected by respiratory motion. This report describes the magnitude of respiratory motion, discusses radiotherapy specific problems caused by respiratory motion, explains techniques that explicitly manage respiratory motion during radiotherapy and gives recommendations in the application of these techniques for patient care, including quality assurance (QA) guidelines for these devices and their use with conformal and intensity modulated radiotherapy. The technologies covered by this report are motion-encompassing methods, respiratory gated techniques, breath-hold techniques, forced shallow-breathing methods, and respiration-synchronized techniques.

Comparison of ghosting effects for three commercial a-Si EPIDs.

Many studies have reported dosimetric characteristics of amorphous silicon electronic portal imaging devices (EPIDs). Some studies ascribed a non-linear signal to gain ghosting and image lag. Other reports, however, state the effect is negligible.

Mid-ventilation CT scan construction from four-dimensional respiration-correlated CT scans for radiotherapy planning of lung cancer patients.

Purpose: Four-dimensional (4D) respiration-correlated imaging techniques can be used to obtain (respiration) artifact-free computed tomography (CT) images of the thorax. Current radiotherapy planning systems, however, do not accommodate 4D-CT data. The purpose of this study was to develop a simple, new concept to incorporate patient-specific motion information, using 4D-CT scans, in the radiotherapy planning process of lung cancer patients to enable smaller error margins.

Short-term and long-term reproducibility of lung tumor position using active breathing control (ABC).

Purpose: To evaluate the short-term and long-term reproducibility of lung tumor position for scans acquired using an active breathing control (ABC) device.

Methods And Materials: Ten patients with lung cancer were scanned over three sessions during the course of treatment. For each session, two scans were acquired at deep inhale, and one scan each at half of deep inhale and at exhale.

Impact of geometrical uncertainties on 3D CRT and IMRT dose distributions for lung cancer treatment.

Purpose: To quantify the effect of set-up errors and respiratory motion on dose distributions for non-small cell lung cancer (NSCLC) treatment.

Methods And Materials: Irradiations of 5 NSCLC patients were planned with 3 techniques, two (conformal radiation therapy (CRT) and intensity modulated radiation therapy (IMRT1)) with a homogeneous dose in the planning target volume (PTV) and a third (IMRT2) with dose heterogeneity. Set-up errors were simulated for gross target volume (GTV) and organs at risk (OARs).