Search results for "Radiation Treatment Planning."

2014

Background and purpose: A substantial reduction of uncertainties in clinical brachytherapy should result in improved outcome in terms of increased local control and reduced side effects. Types of uncertainties have to be identified, grouped, and quantified. Methods: A detailed literature review was performed to identify uncertainty components and their relative importance to the combined overall uncertainty. Results: Very few components (e.g., source strength and afterloader timer) are independent of clinical disease site and location of administered dose. While the influence of medium on dose calculation can be substantial for low energy sources or non-deeply seated implants, the influence…

SU-G-201-02: Application of RayStretch in Clinical Cases: A Calculation for Heterogeneity Corrections in LDR Permanent I-125 Prostate Brachytherapy

2016

Purpose: Tissue heterogeneities and calcifications have significant impact on the dosimetry of low energy brachytherapy (BT). RayStretch is an analytical algorithm developed in our institution to incorporate heterogeneity corrections in LDR prostate brachytherapy. The aim of this work is to study its application in clinical cases by comparing its predictions with the results obtained with TG-43 and Monte Carlo (MC) simulations. Methods: A clinical implant (71 I-125 seeds, 15 needles) from a real patient was considered. On this patient, different volumes with calcifications were considered. Its properties were evaluated in three ways by i) the Treatment planning system (TPS) (TG-43), ii) a M…

Towards clinical application of RayStretch for heterogeneity corrections in LDR permanent 125-I prostate brachytherapy

2017

Purpose RayStretch is a simple algorithm proposed for heterogeneity corrections in low-dose–rate brachytherapy. It is built on top of TG-43 consensus data, and it has been validated with Monte Carlo (MC) simulations. In this study, we take a real clinical prostate implant with 71 125I seeds as reference and we apply RayStretch to analyze its performance in worst-case scenarios. Methods and Materials To do so, we design two cases where large calcifications are located in the prostate lobules. RayStretch resilience under various calcification density values is also explored. Comparisons against MC calculations are performed. Results Dose–volume histogram–related parameters like prostate D90, …

Imaging Approach for Evaluation of Focal Liver Lesions

2009

Focal liver lesions are common in the general population. Radiology (imaging) plays a pivotal role for the diagnosis, staging, treatment planning, and follow-up of focal liver lesions. To maximize lesion detection and characterization, imaging needs to be performed with appropriate equipment by using protocols carefully designed on the basis of the underlying clinical context. In addition, the decision of an imaging modality cannot be based on the diagnostic accuracy of an imaging test solely but must also consider patient safety and cost-effectiveness.

Commissioning and quality assurance procedures for the HDR Valencia skin applicators

2016

The Valencia applicators (Nucletron, an Elekta company, Elekta AB, Stockholm, Sweden) are cup-shaped tungsten applicators with a flattening filter used to collimate the radiation produced by a high-dose-rate (HDR) 192 Ir source, and provide a homogeneous absorbed dose at a given depth. This beam quality provides a good option for the treatment of skin lesions at shallow depth (3-4 mm). The user must perform commissioning and periodic testing of these applicators to guarantee the proper and safe delivery of the intended absorbed dose, as recommended in the standards in radiation oncology. In this study, based on AAPM and GEC-ESTRO guidelines for brachytherapy units and our experience, a set …

Maxillary bone lesions in McCune-Albright syndrome:a case report

2011

Abstract Objectives In this study, we report on the clinical maxillary manifestations of a patient affected by McCune-Albright syndrome and the implications for orthodontic therapy. Materials and methods A male, 8-year-old patient was examined at the Department of Orthodontics of the University of L’Aquila for a problem of anterior open-bite. In the clinical examination, a small swelling of the left hemi-maxilla was seen in the area corresponding to the root apex of 16 and under the tooth buds of 14 and 15. In a panoramic radiograph, a radio-opaque area was detected in this zone. From the computer tomography examination, a bone lesion was identified. Results Identification of this bone lesi…