PURPOSE This study investigates (i) the effect of verification protocols on treatment accuracy and PTV margins for partial breast and boost breast radiotherapy with short fractionation schema (15 fractions), (ii) the effect of deformation of the excision cavity (EC) on PTV margin size, (iii) the imaging dose required to achieve specific PTV margins. METHODS AND MATERIALS Verification images u...

Introduction: The accuracy of the patient setup and tumor location are major factors that determine the efficacy of radiotherapy treatment planning. In the prostate radiotherapy, reproducibility of the prostate location for each treatment fraction is problematic owing to varying filling of the rectum and bladder. According to this, the aim of this study was to measure the inte...

A clinical target volume (CTV) to planning target volume (PTV) margin recipes was routinely used to ensure dose was actually delivered to target for all (most) patients. Currently used margin recipes were associated with only translational set-up errors in radiotherapy. However, when set-up errors extended to six-degree (6D) scope (three translational and three rotational set-up errors), margin...

BACKGROUND PET/CT scans acquired in the radiotherapy treatment position are typically performed without compensating for respiratory motion. The purpose of this study was to investigate geographic miss of lung tumours due to respiratory motion for target volumes defined on a standard 3D-PET/CT. METHODS 29 patients staged for pulmonary malignancy who completed both a 3D-PET/CT and 4D-PET/CT we...

The planning target volume (PTV) includes the clinical target volume (CTV) to be irradiated and a margin to account for uncertainties in the treatment process. Uncertainties in miniature multileaf collimator (mMLC) leaf positioning, CT scanner spatial localization, CT-MRI image fusion spatial localization, and Gill-Thomas-Cosman (GTC) relocatable head frame repositioning were quantified for the...

Rotational setup errors are usually neglected in most clinical centers. An analytical formula is developed to determine the extra margin between clinical target volume (CTV) and planning target volume (PTV) to account for setup errors. The proposed formula corrects for both translational and rotational setup errors and then incorporated into margin determination for PTV.

IntroductionThis study aimed to evaluate the effect of image-guided radiation therapy (IGRT) on the margin between the clinical target volume (CTV) and planning target volume (PTV) in lung cancer. MethodsThe CTV and PTV margin were determined in three dimensions by four radiation oncologists using a standard method in 10 lung cancer patients, and compared to consensus values. Transfer error was...

PURPOSE To compare planning target volume (PTV) defined by PET combined with 4DCT to 3DCT and 4DCT. METHODS Eighteen (18/30) esophageal cancer patients who underwent 3DCT, 4DCT and (18)F-FDG PET-CT thoracic simulation with SUVmax≥2.0 of the primary volume were enrolled. CTV3D was formed on 3DCT by adding a margin of 30 mm in cranial-caudal direction and 5 mm in transversal direction. PTV3D wa...

We evaluated the four-dimensional (4D) dose to a moving target by a Monte Carlo dose calculation algorithm in stereotactic body radiation therapy (SBRT) planning based on the isocenter dose prescription. 4D computed tomography scans were performed for 12 consecutive patients who had 14 tumors. The gross tumor volume (GTV) and internal target volume (ITV) were contoured manually, and the plannin...

The aim of this study was to evaluate the interfractional prostate motion of patients immobilized in the prone position using a thermoplastic shell. A total of 24 patients with prostate calcifications detectable using a kilo-voltage X-ray image-guidance system (ExacTrac X-ray system) were examined. Daily displacements of the calcification within the prostate relative to pelvic bony structures w...