Variety Of Treatment Sites Research Articles

Non‐invasive fat reduction of the flanks using a new cryolipolysis applicator and overlapping, two‐cycle treatments

Background and ObjectivesA sharply contoured cryolipolysis vacuum applicator was developed to improve fit and tissue draw in the abdomen and flanks to better accommodate a range of body types and a variety of treatment sites. This study was carried out to evaluate the safety and efficacy of the new applicator for treatment of flank fat (“love handles”).Study Design/Materials and MethodsA cryolipolysis vacuum applicator with a sharply contoured cup and curved cooling plates was used to treat 20 flanks. Two treatment cycles were delivered sequentially to each flank (60-minute cycle at a Cooling Intensity Factor of 41.6). Efficacy was evaluated 12 weeks post-treatment by physicians performing blinded, independent review of clinical photographs. Safety was assessed by the treating physician monitoring subjects for side effects and adverse events.ResultsFour blinded, independent physician reviewers properly identified the pre- and post-treatment photographs 94.4% of the time. Improvement was scored from 0 (none) to 10 (complete) and showed an average 4.3 point (43%) improvement. Side-effects were limited to erythema, edema, bruising, and numbness or tingling at the treatment site, and resolved without treatment.ConclusionsMultiple treatment cycles from a new improved-fit cryolipolysis applicator are safe and effective for reduction of flank fat bulges. A high degree of improvement was reported by blinded, physician evaluation of standardized photographs. Laser Surg. Med. 46:731–735, 2014. © 2014 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals, Inc.

Assessing the Efficiency and Consistency of Daily Image-guided Radiation Therapy in a Modern Radiotherapy Centre

BackgroundPatients at Radiation Oncology Queensland Toowoomba are treated using the assistance of daily image-guided radiation therapy (IGRT). Each patient's daily setup is exposed to a number of variables. This study investigates the effect that these variables have on the total time taken to analyse field placement and the total time taken for treatment, as well accessing setup error across a variety of treatment types. MethodsThis is a retrospective study of 80 patients across a variety of treatment sites where daily IGRT was undertaken using kilovoltage and megavoltage orthogonal images. Variables investigated include the treatment type, the imaging modality used, and the setup error of each session. Statistical analysis was then performed on the data. ResultsPatients being treated in the thoracic region had the greatest random setup error. The mean matching times were also longer for chest patients (197 seconds), whereas there were minimal differences in times regarding modality. Treatment times were longest for head and neck variables (399–405 seconds). ConclusionsPretreatment daily IGRT is beneficial to all patients and can be performed efficiently. Pelvic variables were the strongest performer, with fiducial markers providing the most consistent and rapid match times. Chest variables were the worst performer specifically regarding random setup error and match times indicating future work required on chest stabilization.

SU-GG-T-125: Incorporating Uncertainty in Radiation Therapy Optimization with Scenario and Voxel Sampling

Purpose: The inclusion of motion and uncertainty in treatment plan optimization requires the use of a potentially large number of geometric instances (scenarios), which may be computationally intractable. We seek to provide a fast, flexible approach that is practical to implement. Method and Materials: When using a gradient‐based optimization method, we have found that not every voxel and scenario needs to be computed at every step to converge to a near‐optimal solution. We first create a model of the dose actually delivered to the patient for a given set of beamlet intensities and geometric scenario. Based on this dose, we calculate the value of an objective function, a measure of how far a dose is from satisfying our clinical goals. We typically minimize the expected value of this objective function. On each step of the optimization, we use several scenario samples to estimate the expected objective. To further speed up the estimate, we only calculate the dose to a fraction of the voxels within the patient per scenario. We use this sampling to estimate the gradient, which we use in a gradient‐based optimization algorithm. At each step of the algorithm we use sample new scenarios and voxels. We automatically tune the sampling rate for various structures by choosing the number of scenarios and voxels samples per step that minimizes the variance in the estimated objective. Results: So far we have tested the algorithm on 5 cases with a variety of treatment sites and several different motion models for IMRT and IMPT. Based on these cases, we find that voxel sampling combined with scenario sampling is over an order of magnitude faster than scenario sampling alone. This acceleration is achieved without sacrificing plan quality. Conclusion: The new approach is a fast, flexible way of incorporating uncertainty into the optimization.

MO-D-351-06: A Generalized Inverse Planning Tool for Arc-Based IMRT Delivery

Purpose: The recent development of new linaccontrol systems that are capable of delivering Volumetric Modulated Arc Therapy (VMAT) has attracted significant attention. There remains, however, a lack of robust inverse planning tools for VMAT. In this study, we will present a generalized inverse planning tool that can provide highly conformal VMAT solutions using either single‐arc or multiple‐arc deliveries for both Varian and Elekta MLCs.Method and Materials: To generate VMAT plans, we first created optimized multi‐field IMRT plans with equal‐spaced beam angles in Pinnacle3 using direct machine parameter optimization (DMPO). A “deliverable” fluence map was reconstructed using the resulting apertures for each beam. Next, we applied our home‐grown arc sequencer to translate these fluence maps into VMAT plans. Based on the user‐defined requirements, the sequencer can provide either single‐arc or multiple‐arc plans that meet the predefined VMAT leaf‐motion constraints. The obtained VMAT plans were then loaded into Pinnacle3 for a final dose calculation. In this study, 10 cases were tested in this study covering a variety of treatment sites including head‐&‐neck(5), prostate(3), lung(1) and brain(1). Results: A total of 24 VMAT plans were created using these 10 cases. Results demonstrated that highly conformal VMAT dose distributions can be achieved with an average sequencing time of under 8 minutes. On average, the VMAT plans required 513 MUs to deliver between 1 to 3 arcs. The average standard deviation in the target dose was 5.79 cGy/fraction; while the average target volume covered by 95% prescribed dose was 98.1%. Our results show that comparable VMAT plans can be achieved using either the Elekta 80‐leaf MLC or the Varian 120‐leaf Millennium MLC.Conclusion: Our generalized arc‐sequencing algorithm serves as a robust inverse planning solution for VMAT. Highly conformal single‐arc or multiple‐arc VMAT plans can be created for Elekta and Varian MLCs.