Search results for "Treatment planning"

EPR/alanine dosimetry for two therapeutic proton beams

2016

Abstract In this work the analysis of the electron paramagnetic resonance (EPR) response of alanine pellets exposed to two different clinical proton beams employed for radiotherapy is performed. One beam is characterized by a passive delivery technique and is dedicated to the eyes treatment (OPTIS2 beam line). Alanine pellets were irradiated with a 70 MeV proton beam corresponding to 35 mm range in eye tissue. We investigated how collimators with different sizes and shape used to conform the dose to the planned target volume influence the delivered dose. For this purpose we performed measurements with varying the collimator size (Output Factor) and the results were compared with those obtai…

Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immunotherapy for the treatment of hepatocellular carcinoma.

2021

Patients with advanced hepatocellular carcinoma (HCC) have historically had few options and faced extremely poor prognoses if their disease progressed after standard-of-care tyrosine kinase inhibitors (TKIs). Recently, the standard of care for HCC has been transformed as a combination of the immune checkpoint inhibitor (ICI) atezolizumab plus the anti-vascular endothelial growth factor (VEGF) antibody bevacizumab was shown to offer improved overall survival in the first-line setting. Immunotherapy has demonstrated safety and efficacy in later lines of therapy as well, and ongoing trials are investigating novel combinations of ICIs and TKIs, in addition to interventions earlier in the course…

Review of clinical brachytherapy uncertainties: Analysis guidelines of GEC-ESTRO and the AAPM

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…

Three-dimensional conformal radiotherapy in localized carcinoma of prostate: preliminary reports of toxicity in dose-escalation treatment

2007

Purpose Many studies confirmed the evidence of a dose-response relationship in prostate cancer. Escalation of dose using conventional techniques is however limited by rectal tolerance. IMRT and 3D-CRT have been designed to allow dose escalation while not exceeding rectal tolerance. We evaluated the acute and early late tolerance to surrounding organs upon dose escalation from 70 to 78 Gy in 3D-CRT setting, in order to introduce the IMRT process as a routine practice in prostate cancer treatment. Materials and Methods We compared clinical data from 35 patients with localized adenocarcinoma of the prostate, who received 70 Gy within a traditional reconstructed three-dimensional treatment plan…

Influence of Three-dimensional Imaging on Implant Treatment Planning: Implant Diameter and Length

2018

Aim To investigate the influence of the radiographic modalities panoramic radiography (PR) and cone beam computed tomography (CBCT) on selection of implant length and diameter. Materials and methods Potential implant sites (59 sites, 40 patients) with available PRs and CBCTs were selected from the databases of two University dental schools. Six experienced clinicians were asked to select the appropriate implant length and diameter based on PR and CBCT. Results were compared with the actual surgical procedure and intra- /interrater agreement was calculated using Cohen's kappa. Results On average, greater implant length was more often planned based on PR (24.2 vs 8.8% with CBCT), while wider …

Which factors influence orthodontists in their decision to extract? A questionnaire survey

2019

Background To evaluate the relative influence of different criteria in the choice between extraction and nonextraction treatment in current orthodontics, and to assess how the percentage of extractions has evolved over time. Material and methods Pre-treatment records (panoramic radiograph, lateral cephalogram, study casts and photographs) of fourteen cases in permanent dentition (adult or adolescent) with class I molar relationship and moderate anterior crowding were evaluated by 28 orthodontists. For each case, each orthodontist filled out a questionnaire reporting his treatment plan proposal (extraction or nonextraction) and the importance of specific parameters in his decision-making pro…

Implementation of advanced methodologies in the commissioning of a Light Ion Beam Therapy facility

Utility of imaging techniques in the diagnosis of oral cancer.

2015

Abstract Purpose Imaging techniques such as magnetic resonance imaging (MRI), computed tomography (CT), and positron emission tomography (PET) are often used to complement the clinical exploration and staging of oral squamous cell carcinoma (OSCC). Which of these techniques is best in establishing correct staging and treatment planning is not clear, however. This study aims to determine which technique is most appropriate for diagnosing the primary tumor and for detecting bone invasion and neck metastases. Material and methods A Medline literature search was made over the last 10 years. In each selected study, we recorded the sample size and sensitivity, specificity and precision. Strengths…

Dosimetric characteristics of the CDC-type miniature cylindrical 137Cs brachytherapy sources

2002

The low dose rate CDC-type miniature cylindrical 137 Cs sources are available, with one or three active beads, for use in source trains in automatic and manual afterloading systems for gynecological brachytherapy. Absolute dose rate distributions in water have been calculated around these sources using the Monte CarloGEANT3 code and they are presented as conventional two-dimensional Cartesian lookup tables. The AAPM Task Group 43 formalism for dose calculation has been also applied. The dose rate constant obtained for the one bead source is Λ=1.113±0.003 cGyh −1 U −1 , and the value for the three bead source is Λ=1.103±0.003 cGyh −1 U −1 . Finally, for the treatment planning systems based o…

Dosimetry revisited for the HDR I192r brachytherapy source model mHDR-v2

2010

Purpose: Recently, the manufacturer of the HDR I 192 r mHDR-v2 brachytherapysource reported small design changes (referred to herein as mHDR-v2r) that are within the manufacturing tolerances but may alter the existing dosimetric data for this source. This study aimed to (1) check whether these changes affect the existing dosimetric data published for this source; (2) obtain new dosimetric data in close proximity to the source, including the contributions from I 192 r electrons and considering the absence of electronic equilibrium; and (3) obtain scatterdose components for collapsed cone treatment planning system implementation. Methods: Three different Monte Carlo(MC) radiation transport co…