Simple Factors Associated With Radiation-Induced Lung Toxicity After Stereotactic Body Radiation Therapy of the Thorax: A Pooled Analysis of 88 Studies

To study the risk factors for radiation-induced lung toxicity (RILT) after stereotactic body radiotherapy (SBRT) of the thorax

Transmitter diversity code design for achieving full diversity on Rayleigh fading channels

Traditional code design for fading channels assumes that interleaving is able to make the fading on all received symbols independent. However, the ideal interleaving depth depends on vehicle speed via the Doppler rate. If the vehicle stops, infinite interleaving depth would be required. Transmitter diversity may be used to achieve independent fading without interleaving, even in the presence of zero Doppler. Even so, not all of the fading samples are uncorrelated, and this must be taken into account in code design or the desired diversity might not be achieved. In this work convolutional trellis codes are presented which utilize the full diversity capability of the system. A multichannel signaling model is presented which can accommodate transmitter diversity in addition to time diversity, receiver antenna diversity, and frequency diversity. The exact pairwise error event probability for frequency non-selective Rayleigh fading channels is derived for this model. At high signal-to-noise ratio a tight upper bound is derived. Examination of the error bound shows that the most important design metrics for transmitter diversity on Rayleigh fading channels are the minimum (1) effective Hamming distance ([special characters omitted]) and (2) effective product distance ([special characters omitted]). It is shown that for independent fading with one level of transmitter diversity these metrics are equivalent to the traditional Hamming and product distances. Useful properties of the design metrics are proven. It is shown how to compute [special characters omitted] and [special characters omitted] recursively. This allows efficient algorithms such as the Viterbi algorithm to be employed for code analysis. It is proven that under certain restrictions, codes which are geometrically uniform with respect to [special characters omitted] can only achieve one level of diversity. Other techniques to obtain space-time codes with a uniform distance spectrum are investigated. Design rules are presented which guarantee full diversity codes for any desired diversity level and throughput. Numerous codes are presented

EFFICENT USE OF NARROWBAND RADIO CHANNELS FOR MOBILE DIGlTAL COMMUNICATIONS

The Intelligent Transportation System (ITS) relies heavily on data communications systems to link field equipment such as traflic: sensors, changeable message signs and incident response vehicles with traffic operations centers. The Federal Highway A~iministration (FHWA) has received an allocation of five channels in the 220 MHz band to provide a communication resource for ITS applications. This report investigates a high efficiency mobile \vireless modem with a spectral efficiency of 3 bps&. The modem incorporates the following techniques to compensate for the fading channel: transmitter antenna diversity, modulation using intentional frequency offset, interleaved block codles, symbol timing and frame synchr~mizationo ptimized for fading channels, soft decision decoding optimized for fading, and pilot symbol assisted modulation (PSAM) channel estimation. A prototype of this wireless modem has been constructed and subjected to full bench testing. Preliminary field testing has been performed and more is in progress

Estimating the tolerance of brachial plexus to hypofractionated stereotactic body radiotherapy: a modelling-based approach from clinical experience.

BACKGROUND: Brachial plexopathy is a potentially serious complication from stereotactic body radiation therapy (SBRT) that has not been widely studied. Therefore, we compared datasets from two different institutions and generated a brachial plexus dose-response model, to quantify what dose constraints would be needed to minimize the effect on normal tissue while still enabling potent therapy for the tumor. METHODS: Two published SBRT datasets were pooled and modeled from patients at Indiana University and the Richard L. Roudebush Veterans Administration Medical Center from 1998 to 2007, as well as the Karolinska Institute from 2008 to 2013. All patients in both studies were treated with SBRT for apically located lung tumors localized superior to the aortic arch. Toxicities were graded according to Common Terminology Criteria for Adverse Events, and a probit dose response model was created with maximum likelihood parameter fitting. RESULTS: This analysis includes a total of 89 brachial plexus maximum point dose (Dmax) values from both institutions. Among the 14 patients who developed brachial plexopathy, the most common complications were grade 2, comprising 7 patients. The median follow-up was 30 months (range 6.1-72.2) in the Karolinska dataset, and the Indiana dataset had a median of 13 months (range 1-71). Both studies had a median range of 3 fractions, but in the Indiana dataset, 9 patients were treated in 4 fractions, and the paper did not differentiate between the two, so our analysis is considered to be in 3-4 fractions, one of the main limitations. The probit model showed that the risk of brachial plexopathy with Dmax of 26 Gy in 3-4 fractions is 10%, and 50% with Dmax of 70 Gy in 3-4 fractions. CONCLUSIONS: This analysis is only a preliminary result because more details are needed as well as additional comprehensive datasets from a much broader cross-section of clinical practices. When more institutions join the QUANTEC and HyTEC methodology of reporting sufficient details to enable data pooling, our field will finally reach an improved understanding of human dose tolerance

Multisession Radiosurgery for Hearing Preservation.

Clinically relevant dose-tolerance limits with reliable estimates of risk in 1-5 fractions for cochlea are still unknown. Timmerman׳s limits from the October 2008 issue of Seminars in Radiation Oncology have served as the basis for clinical practice, augmented by updated constraints in TG-101 and QUANTEC, but the corresponding estimates of risk have not yet been well-reported. A total of 37 acoustic neuroma CyberKnife cases from Medstar Georgetown University Hospital treated in 3 or 5 fractions were combined with single-fraction Gamma Knife data from the 69 cases in Timmer 2009 to form an aggregate dataset of 106 cochlea cases treated in 1-5 fractions. Probit dose-response modeling was performed in the DVH Evaluator software to estimate normal tissue complication probability. QUANTEC recommends keeping single-fraction maximum dose to the cochlea less than 14Gy to maintain less than 25% risk of serviceable hearing loss, and our 17.9% risk estimate for 14Gy in 1 fraction is within their predicted range. In 5 fractions, our estimate of the Timmerman 27.5Gy maximum cochlea dose limit was 17.4%. For cases in which lower risk is required, the Timmerman 12Gy in 1 fraction and the TG-101 limit of 25Gy in 5 fractions had an estimated risk level of 11.8% and 13.8%, respectively. High-risk and low-risk dose tolerance with risk estimates in 1-5 fractions are all presented