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Hydrogel spacers (HS) have been widely used in radiotherapy to reduce rectal toxicity while escalating dose for prostate cancer. Saline-filled biodegradable balloon spacers (BS) have been developed and recently introduced for prostate brachytherapy. A retrospective review was performed to compare dosimetry of high-dose-rate brachytherapy (HDR-BT) patients implanted with these spacers. Prostate cancer patients were treated with HDR-BT either without spacer (NS), with HS (SpaceOARTM Hydrogel from Boston Scientific Corp.), or with BS (BioProtect balloon from BioProtect Ltd.) implanted between the prostate and rectum. Eleven patients who underwent whole prostate gland treatment were sampled for each group. Patients who received monotherapy (27-29 Gy in 2 fractions) or combination therapy (15 Gy in 1 fraction + EBRT) were included in this study. The spacer, target, and organs at risk (OAR) including the rectum, bladder, and urethra were contoured on CT and MR images (Fig. 1). The volume and diameter of the spacer were measured. In the treatment plan, target coverage (D90%, V100%, and V150%) and OAR doses (D0.1cc, D1cc, and D2cc , and V75%) between the groups were compared using an unpaired t-test. The median volume of the spacer was 10.6 cc (7.2 - 15.1 cc) for HS and 14.4 cc (10.3 - 16.3 cc) for BS. The median anterior-posterior distance between the prostate and the rectum at the mid-gland was 0.5 cm (0.3 - 0.8 cm) for NS, 1.0 cm (0.7 - 1.4 cm) for HS, and 1.8 cm (1.5 - 2.0 cm) for BS. Similar target coverages (median D90 = 106% (105 - 110%, p = 0.5) for NS, 105% (104 - 108%, p = 0.8) for HS, and 106% (104 - 110%) for BS) were achieved from the three groups. A statistically significantly lower dose to the rectum was observed for BS when compared to NS or HS (median D2cc = 61% (48 - 70%, p < 0.001) for NS, 53% (50 - 67%, p = 0.01) for HS, and 44% (34 - 59%) for BS). No statistical differences in dose to the bladder were observed (median D2cc = 66% (45 - 70%, p =0.08) for NS, 66% (56 - 71%, p = 0.3) for HS, and 68% (58 - 74%) for BS). A statistically significant increase in maximum dose to the urethra was observed with BS when compared to NS and HS (D0.1cc = 107.8% (103.7 - 110.0%, p < 0.001) for NS, 109.7% (107.0 - 109.9%, p = 0.003) for HS, and 110.3% (109.6 - 113.1%) for BS). The use of saline-filled biodegradable BS has the benefit of significantly reducing rectal dose compared to HS while providing the same target dose coverage. However, the filling volume must be carefully determined, as injecting large amounts of saline may deform the prostate and displace implanted catheters close to the urethra, creating hot spots in the urethra. Further studies are necessary to evaluate the impact of these dosimetric differences on clinical outcomes. [ABSTRACT FROM AUTHOR]

Surgery and radiation therapy are standard treatments for lip cancer. Surgery includes removal of all cancer-related tissue and facial reconstruction (cosmetic and functional) of the lips. Reconstruction procedures are available but give a less satisfactory cosmetic result than brachytherapy. In addition, the use of high-dose-rate brachytherapy (HDR-BT) is now becoming more popular than low-dose-rate (LDR) and pulsed-dose-rate (PDR) BT in the treatment of lip cancer since HDR-BT offers the advantage of optimizing dose distribution by varying dwell times. However, due to the short history of use of HDR-BT, relatively few studies on HDR have been published. Two institutions (Ukraine and USA) reviewed the clinical outcomes of lip cancer patients treated with HDR-BT. An interstitial (IS), surface custom mold (SC), or a combination of IS and SC applicator (IS + SC) was used for treatments based on the depth of tumor invasion. Clinical target volume (CTV) was determined by adding 1 cm to the initial visible lesion (gross tumor volume (GTV)). Brachytherapy prescription dose was 24 Gy in 6 fractions in addition to 45-50 Gy for EBRT. If brachytherapy was use as a monotherapy, 50 Gy in 10 fractions was prescribed. Interstitial technique was considered first because of conformal irradiated volume and treatment accuracy (Fig. 1). Typically, 1 to 3 interstitial tubes have been evaluated as sufficient for the planned volume. Optimal spacing between tubes is 1.1-1.3 cm. During the evaluation and optimization of the treatment plan, if adding one or more catheters superficially helped the dose distribution and coverage, one or two additional catheters were added for IS+SC. For tumors less than 5mm deep, SCs were created manually or 3D-printed and used for treatment. Since some implantations and applicator design were suboptimal, manual or inverse planning followed by graphical optimization was used to meet target coverage goal and OAR constraints. A total of 33 cases of lip cancer from two institutions were treated from 2015 to 2021. The median age of the patients was 63 years (range, 42-85). Sixty percent of the patients were males, and forty percent were females. Three patients underwent immunosuppression after lung transplant. By using TNM staging classification for skin cancer, there were 14 stage I (42.4%), 15 stage II (45.5%), and 4 stage III (12.1%) lip cancers. Thirty-one patients (93.9%) had complete responses to treatment. Only 2 patients (6.1%) displayed local recurrences. Grade 1, 2, and 3 acute toxicities were observed in 30.3%, 51.5%, and 18.2% of patients, respectively. Grade 1, 2, and 3 late toxicities were observed in 39.4%, 21.2%, and 0.0% of cases. Cosmetic results were excellent in 21.2%, good in 54.5%, fair in 18.2%, and poor in 6.1% of patients. HDR Brachytherapy can deliver the most conformal radiation dose to the lip cancers. HDR-BT using IS, SC, or IS + SC is an effective treatment for the lip cancer with good outcomes and cosmetic results. The IS approach provides more heterogeneous and local distribution. The SC applicators provides more uniform dosimetry than the IS technique, but typically has a larger irradiated volume. The SC may be good solution for lip brachytherapy, since it is not invasive. However, it has been rarely used since it is quite difficult to make skin mold applicators to fit the irregular surface of the lip. [ABSTRACT FROM AUTHOR]

Purpose To assess the magnitude of dosimetric reductions of a focal and ultra-focal high-dose-rate (HDR) prostate brachytherapy treatment strategy relative to standard whole gland (WG) treatment. Methods and Materials HDR brachytherapy plans for five patients treated with WG HDR monotherapy were optimized to assess different treatment strategies. Plans were generated to treat the hemigland (HG), one-third gland (1/3G), and one-sixth gland (1/6G), as well as to assess treating the WG with a boost to one of those sub-volumes (WG + HG, WG + 1/3G, WG + 1/6G). Dosimetric parameters analyzed included Target D90%, V100%, V150%, Bladder (B), Rectal (R), Urethral (U) D0.1, 1 and 2cc, Urethral V75%, and the V50% to the contralateral HG. Two-tailed t tests were used for comparison of means, and p -values less than 0.05 were considered statistically significant. Results Target objectives (D90 > 100% and V100 > 97%) were met in all cases. Significant organs at risk dose reductions were achieved for all approaches compared with WG plans. 1/6G vs WG plans resulted in the greatest reduction in dose with a mean bladder D2cc 24.7 vs 64.8%, rectal D2cc 32.8 vs 65.3%, urethral D1cc 52.1 vs 103.8%, and V75 14.5 vs 75% ( p < 0.05 for all comparisons). Conclusion Significant dose reductions to organs at risk can be achieved using HDR focal brachytherapy. The magnitude of the reductions achievable with treating progressively smaller sub-volumes suggests the potential to reduce morbidity, but the clinical impact on morbidity and tumor control remain to be investigated. [ABSTRACT FROM AUTHOR]

Purpose High-dose-rate (HDR) prostate brachytherapy delivers a heterogeneous dose distribution throughout the prostate gland. There is however limited information regarding the spatial distribution of this dose heterogeneity. To this end, we analyzed the magnitude and location of intraprostatic dose heterogeneity in HDR prostate brachytherapy. Methods and Materials Five consecutive prostate cancer patients treated with HDR were analyzed. Based on CT-simulation images, each prostate was divided into three sections (apex, base, and mid-gland). These were further subdivided into eight symmetrical sections to give a total of 24 sections. Dose–volume histograms were analyzed from V100–V200% for these 24 sections comparing the means of individual regions, left vs right, apex vs base vs mid-gland, lateral vs medial, and anterior vs posterior. A separate analysis on dose as a function of individual region volume was also performed. Results Analyses comparing the 24 regions showed a maximum 62% difference (range, 21.9–83.9%) at V130% and 19.9% (1.9–20.8%) at V200%. Seven regions were significantly decreased and one significantly elevated from V130–V180% when compared with the mean. The means for lateral sections were 1.57-fold higher than medial sections from V110–V200% ( p < 0.0001). The dose at the base was significantly higher than the rest of the gland from V120–V200 (V150, 35.6 ± 16.2% vs 20.9 ± 13.1%, p < 0.0001). Conclusions There is significant intra-prostatic dose heterogeneity in prostate HDR brachytherapy. This is most notable in the increased dose to base and lateral portions of the gland. Further studies are needed to determine the impact of heterogeneity on clinical outcomes. [ABSTRACT FROM AUTHOR]

Purpose: To study the dosimetric differences of various channel combinations of the Capri vaginal applicator. Methods and Materials: The Capri consists of a single central channel (R1), an inner array of 6 channels (R2), and an outer array of 6 channels (R3). Three-dimensional plans were simulated for 6 channel arrangements (R1, R2, R12, R13, R23, and R123). Treatment plans were optimized to the applicator surface or 5-mm depth while minimizing dose to organs at risk (OARs: bladder, rectum, sigmoid, and urethra). The clinical target volume (CTV) was defined as a 5-mm circumferential shell extending 4 cm in length around the applicator. Clinical target volume coverage (Dmean, D90, V100, and V150) and OAR doses (D0.1 cm3 , D1 cm3 , D2 cm3 , and Dmean) were compared. A comparison between the Capri (R123) and a conventional single-channel applicator was also done. Statistical significance (P value <.05) was evaluated with a 2-tailed t test. Results: When prescribing to 5-mm depth, CTV coverage using all 13 channels (R123) versus a single channel (R1) was similar; however, when prescribing to the surface there were differences (P<.0001) in all CTV metrics except for the V150. The R1 plans had higher doses to all OARs compared with R123 plans (P<.007). Doses to OARs were not significantly different between R23 and R123 plans (P=.05-.95), and CTV coverage differences were on the order of 1%. Capri R123 plans provided slightly lower CTV D90 and Dmean but equivalent OAR doses with smaller standard deviations compared with conventional cylinder plans for both prescriptions. Conclusions: The Capri multichannel applicator provides equivalent target coverage at 5-mm depth, with significantly reduced dose to OARs relative to using a single channel. Optimal plans can be achieved using R12 (lowest V150) or R123 or R23 (lowest OAR doses). [Copyright &y& Elsevier]

This paper presents a compact low-loss tunable X-band bandstop filter implemented on a quartz substrate using both miniature RF microelectromechanical systems (RF-MEMS) capacitive switches and GaAs varactors. The two-pole filter is based on capacitively loaded folded-λ/2 resonators that are coupled to a microstrip line, and the filter analysis includes the effects of nonadjacent inter-resonator coupling. The RF-MEMS filter tunes from 11.34 to 8.92 GHz with a -20-dB rejection bandwidth of 1.18%-3.51% and a filter quality factor of 60-135. The GaAs varactor loaded filter tunes from 9.56 to 8.66 GHz with a -20-dB bandwidth of 1.65%-2% and a filter quality factor of 55-90. Nonlinear measurements at the filter null with Δƒ = 1 MHz show that the RF-MEMS loaded filter results in >25-dBm higher third-order intermodulation intercept point and P-1 dB compared with the varactor loaded filter. Both filters show high rejection levels (>24dB) and low passband insertion loss (<0.8 dB) from dc to the first spurious response at 19.5 GHz. The filter topology can be extended to higher order designs with an even number of poles. [ABSTRACT FROM AUTHOR]

Low-loss tunable filters with three different fractional-bandwidth variations were designed and fabricated ϵr = 2.2,0.787 mm Duroid substrates for 850-1400-MHz applications. A detailed analysis for realizing predefined bandwidth characteristics is presented, and a design technique to take into account the source and load impedance loading is discussed. It is found that independent electric and magnetic coupling makes it possible to realize three different coupling coefficient variations with the same filter structure. The proposed topology is different from the comb-line design in that all three filters have identical electrical lengths, the same varactors, and the same filter Q values. Three different filters are built using Schottky varactor diodes with a tuning range from ∼ 850 to ∼ 1400 MHz. The constant fraction-bandwidth filter has a 1-dB bandwidth of 5.4% ± 0.3% and an insertion loss of 2.88-1.04 dB. The decreasing fractional-band- width filter shows a 1-dB bandwidth decrease from 5.2% to 2.9% with an insertion loss of 2.89-1.93 dB (this is effectively a 40-45-MHz constant absolute-bandwidth filter). The increasing fractional-bandwidth filter shows a 1-dB bandwidth increase from 4.3% to 6.5% with an insertion loss of 3.47-1.18 dB. The measured Q of the filters are between 53-152 from ∼ 850 to ∼ 1400 MHz. The measured third-order intermodulation intercept point ranges from 11.3 to 20.1 dBm depending on the bias voltage. To our knowledge, these planar tunable filters represent state-of-the art insertion-loss performance at this frequency range. [ABSTRACT FROM AUTHOR]

In order to assess the effects of positron range and acolinearity on image resolution of a Compton PET scanner designed for sub-millimeter resolution in mice, Monte Carlo simulations were performed using EGS4 code. The PET device consists of a BGO ring (17.6 cm dia., 16 cm length, and 2 cm thickness segmented into 3 mm × 3 mm × 20 mm crystals) surrounding a concentric position-sensitive silicon ring (4 cm dia. × 4 cm long × 1.6 cm thick segmented into 16 layers of 0.3 mm × 0.3 mm × 1 mm elements) for the scatter detector. For each detected event, interaction position was obtained from the silicon pad in which a single Compton scatter occurs and the BGO crystal which has maximum energy deposited. Acolinearity was considered in sampling the direction vector of annihilation photon pairs. The cusp-like distribution of positron range in water was added in sinogram. An intrinsic detector resolution of 230 μm FWHM is obtained. By considering positron range and acolinearity, the overall image resolutions of 18F, 11C, 13N, and 15O point sources in water are 360, 440, 490, and 550 μm FWHM, respectively. Image quality was evaluated with 2-D images of cylindrical source for each positron emitter in a water cylinder reconstructed with filtered back projection (FBP). Monte Carlo simulation indicates the blurring effect from positron range of various isotopes dominates the image resolution of the Compton PET instrument. A negligibly small effect on resolution was introduced from acolinearity due to the small diameter of the silicon detector. [ABSTRACT FROM AUTHOR]

Abstract: A very high-resolution small animal positron emission tomograph (PET), which can achieve sub-millimeter spatial resolution, is being developed using silicon pad detectors. The prototype PET for a single slice instrument consists of two 1mm thick silicon pad detectors, each containing a 32×16 array of 1.4×1.4mm pads readout with four VATAGP3 chips which have 128 channels low-noise self-triggering ASIC in each chip, coincidence units, a source turntable and tungsten slice collimator. The silicon detectors were located edgewise on opposite sides of a 4cm field-of-view to maximize efficiency. Energy resolution is dominated by electronic noise, which is 0.98% (1.38keV) FWHM at 140.5keV. Coincidence timing resolution is 82.1ns FWHM and coincidence efficiency was measured to be 1.04×10−3% from two silicon detectors with annihilation photons of 18F source. Image data were acquired and reconstructed using conventional 2-D filtered-back projection (FBP) and a maximum likelihood expectation maximization (ML-EM) method. Image resolution of approximately 1.45mm FWHM is obtained from 1-D profile of 1.1mm diameter 18F line source image. Even better resolution can be obtained with smaller detector element sizes. While many challenges remain in scaling up the instrument to useful efficiency including densely packed detectors and significantly improved timing resolution, performance of the test setup in terms of easily achieving sub-millimeter resolution is compelling. [Copyright &y& Elsevier]

• Derivation of DCGL for the Kori Unit 1with different codes. • Researching the possibility of RESRAD-OFFSITE code application to the decommissioning. • Analysis of the results of the RESRAD-ONSITE and RESRAD-OFFSITE codes in the macroscopic point of view. The successful decommissioning of nuclear facilities requires the derivation of DCGL in accordance with national site release criteria. MARSSIM, a widely used decommissioning guideline, recommends that a probabilistic analysis should be performed to derive the DCGL, which can be done by using the RESRAD code. Among the RESRAD codes, the RESRAD-OFFSITE code is the latest software edition and can derive exposure dose of receptor located both on and off-site. In this study, the preliminary exposure dose and DCGL were obtained by using the RESRAD-OFFSITE code and compared with the results obtained by the RESRAD-ONSITE code. As a result of the analysis, it was found that some radionuclides exhibited similar exposure doses and DCGL values, whereas a deviation is observed in a few cases. In this study, the applicability of the RESRAD-OFFSITE code to the decommissioning was investigated, and the similarities and differences with the RESRAD-ONSITE code were analyzed. [ABSTRACT FROM AUTHOR]

The decommissioning of nuclear facilities indicates that the site is finally released according to a limited or unlimited site reuse purpose. In this process, the assessment of exposure dose to decommissioning workers and nearby residents is essential. Based on MARSSIM, a widely used decommissioning guideline in the United States, derivation of the exposure dose and derived concentration guideline level (DCGL) is mandatory using the probabilistic analysis of the RESRAD code. Here, DCGL is the radionuclide-specific concentration that satisfies the site release criteria. By applying the priority 1 parameter, which has the greatest effect on the dose, the dose is derived through deterministic and probabilistic analyses. The results were compared and analyzed. The purpose of this study was to provide a basic database that can be applied to the development of parameter lists and distributions suitable for the characteristics of nuclear facilities in South Korea. In addition, the process of deriving the dose by applying the deterministic and probabilistic analyses of RESRAD was assessed. [ABSTRACT FROM AUTHOR]

Introduction: To identify differences in acute urinary and sexual toxicity between a 6-fraction and 2-fraction high-dose-rate brachytherapy monotherapy regimen and correlate dosimetric constraints to short-term toxicity.Methods: A single institution retrospective study of 116 men with prostate cancer treated with HDR monotherapy from 2010 to 2015 was conducted. Eighty-one men had 7.25 Gy × 6-fractions and 35 men had 13.5 Gy × 2-fractions. Patients had two CT-planned implants spaced 1-2 weeks apart. Patient baseline characteristics, International Prostate Symptom Scores (IPSS) and Sexual Health Inventory for Men (SHIM) scores were collected pre-treatment and 3, 6 and 12 months post-implantation. Mixed effect modelling was undertaken to compare baseline, 1-6 month and 7-12 month scores between groups. Poisson regression analysis was performed to correlate dosimetric constraints with acute toxicity.Results: There was no difference between baseline and post-implantation IPSS scores between 6-fraction and 2-fraction groups. SHIM scores for men treated with 6-fractions had a steeper decline at 1-6 months, but resolved at 7-12 months. Pre-treatment alpha-blocker use correlated with worse short-term acute urinary toxicity. Worsened SHIM score correlated with increasing age, diabetes mellitus and androgen-deprivation therapy. In a dosimetric analysis of outcomes, prostate V150 dose and bladder wall (D01.cc, D1cc, D2cc) dose correlated with increased IPSS score.Conclusion: No increased acute genitourinary or sexual dysfunction has been observed in men when transitioning from 6-fraction to 2-fraction HDR monotherapy. A dosimetric correlation was found between the V150 and bladder wall doses for acute urinary toxicity. Future research should continue to standardize and validate dose constraints for prostate HDR monotherapy patients. [ABSTRACT FROM AUTHOR]

Analyzes the effects of the process parameters on the low-temperature silicon homoepitaxial growth in an ultrahigh-vacuum electron-cyclotron-resonance chemical-vapor-deposition system by reflection high-energy electron diffraction and transmission electron microscopy. Details on the experiment; Results of the study; Conclusion.

Background: High dose rate (HDR) brachytherapy is commonly used to treat prostate cancer. Existing HDR planning systems solve the dwell time problem for predetermined catheters and a single energy source. Purpose: Additional degrees of freedom can be obtained by relaxing the catheters' pre‐designation and introducing more source types, and may have a dosimetric benefit, particularly in improving conformality to spare the urethra. This study presents a novel analytical approach to solving the corresponding HDR planning problem. Methods: The catheter and dual‐energy source selection problem was formulated as a constrained optimization problem with a non‐convex group sparsity regularization. The optimization problem was solved using the fast‐iterative shrinkage‐thresholding algorithm (FISTA). Two isotopes were considered. The dose rates for the HDR 4140 Ytterbium (Yb‐169) source and the Elekta Iridium (Ir‐192) HDR Flexisource were modeled according to the TG‐43U1 formalism and benchmarked accordingly. Twenty‐two retrospective HDR prostate brachytherapy patients treated with Ir‐192 were considered. An Ir‐192 only (IRO), Yb‐169 only (YBO), and dual‐source (DS) plan with optimized catheter location was created for each patient with N catheters, where N is the number of catheters used in the clinically delivered plans. The DS plans jointly optimized Yb‐169 and Ir‐192 dwell times. All plans and the clinical plans were normalized to deliver a 15 Gy prescription (Rx) dose to 95% of the clinical treatment volume (CTV) and evaluated for the CTV D90%, V150%, and V200%, urethra D0.1cc and D1cc, bladder V75%, and rectum V75%. Dose‐volume histograms (DVHs) were generated for each structure. Results: The DS plans ubiquitously selected Ir‐192 as the only treatment source. IRO outperformed YBO in organ at risk (OARs) OAR sparing, reducing the urethra D0.1cc and D1cc by 0.98% (p=2.22∗10−9$p\ = \ 2.22*{10^{ - 9}}$) and 1.09% (p=1.22∗10−10$p\ = \ 1.22*{10^{ - 10}}$) of the Rx dose, respectively, and reducing the bladder and rectum V75% by 0.09 (p=0.0023$p\ = \ 0.0023$) and 0.13 cubic centimeters (cc) (p=0.033$p\ = \ 0.033$), respectively. The YBO plans delivered a more homogenous dose to the CTV, with a smaller V150% and V200% by 3.20 (p=4.67∗10−10$p\ = \ 4.67*{10^{ - 10}}$) and 1.91 cc (p=5.79∗10−10$p\ = \ 5.79*{10^{ - 10}}$), respectively, and a lower CTV D90% by 0.49% (p=0.0056$p\ = \ 0.0056$) of the prescription dose. The IRO plans reduce the urethral D1cc by 2.82% (p=1.38∗10−4$p\ = \ 1.38*{10^{ - 4}}$) of the Rx dose compared to the clinical plans, at the cost of increased bladder and rectal V75% by 0.57 (p=0.0022$p\ = \ 0.0022$) and 0.21 cc (p=0.019$p\ = \ 0.019$), respectively, and increased CTV V150% by a mean of 1.46 cc (p=0.010$p\ = \ 0.010$) and CTV D90% by an average of 1.40% of the Rx dose (p=8.80∗10−8$p\ = \ 8.80*{10^{ - 8}}$). While these differences are statistically significant, the clinical differences between the plans are minimal. Conclusions: The proposed analytical HDR planning algorithm integrates catheter and isotope selection with dwell time optimization for varying clinical goals, including urethra sparing. The planning method can guide HDR implants and identify promising isotopes for specific HDR clinical goals, such as target conformality or OAR sparing. [ABSTRACT FROM AUTHOR]

HDR prostate brachytherapy automated catheter preplanning methods in literature are effective, but do not consider the full solution space of feasible catheter trajectories as they are limited by the catheter-first nature of optimizing treatment times based on a fixed catheter implant. Instead, we propose a block optimization system to simultaneously optimizes isotope dwell time and dwell positions via curved treatment catheter trajectory prediction. Our holistic HDR treatment planning algorithm follows an alternating block structure to optimize dwell times, catheter groupings, catheter trajectories, and dwell positions cyclically to produce an implant catheter distribution and associated treatment plan. The dwell time optimization block leverages the fast iterative shrinkage thresholding algorithm (FISTA) to analytically determine optimal isotope dwell times. Catheter groupings were determined via normalized graph cutting to partition (or associate) dwell positions onto individual catheters. Catheter trajectories were determined with 3D spline fitting. Dwell positions were spatially optimized to guarantee that all dwell positions lie on a treatment catheter in the final plan. The four blocks were alternatingly executed to produce a deliverable treatment plan with optimal catheter trajectories for a single retrospective HDR patient. The block-optimized catheter trajectory distribution was evaluated for feasibility, and the plan dose volume histogram (DVH) was compared to the clinical plan. The block-optimized plan dosimetry is comparable to the clinically delivered plan based on manually placed catheters by an expert, as shown in Figure 1a. For the optimized plan, urethra V75 = 2.93cc, bladder V75 = 2.32cc, and rectum V75 = 0cc, compared to urethra V75 = 3.05cc, bladder V75 = 1.83cc, and rectum V75 = 0.17cc for the clinical plan. While there are tradeoffs in the OAR metrics, this is likely due to optimization weighting in the dwell time module and the overall DVH similarity supports the efficacy of our treatment planning system. Further, the predicted curved catheter trajectories shown in Figure 1b appear physically feasible and mimic the clinically popular peripheral loading technique. Our groundbreaking integrative treatment planning system creates clinically feasible treatment plans with optimized curved catheter trajectories. This shows promise as a method for generating better catheter distributions and integrating with novel robotic insertion mechanisms.] [ABSTRACT FROM AUTHOR]

Purpose To report early clinical outcomes of high-dose-rate interstitial image-guided brachytherapy (BT) in the definitive management of locally advanced cervical cancer. Methods We retrospectively analyzed 31 locally advanced cervical cancer patients treated at our institution between January 2010 and April 2013. About 88% had advanced disease based on the International Federation of Gynecology and Obstetrics guidelines, and 87% received concurrent chemotherapy. All patients were treated with external beam radiation therapy to a median dose of 45 Gy (range, 39.6–58 Gy) before receiving BT. High-dose-rate BT was delivered in a single implant to a median dose of 6 Gy × five fractions to a CT-defined volume. Median total equivalent 2-Gy dose, dose covered by 90% of the high-risk clinical target volume (HR-CTV D 90 ), and HR-CTV were 84, 87.4, and 49.9 cc, respectively. Kaplan–Meier method was used for actuarial survival analysis, and toxicity was graded using Common Terminology Criteria for Adverse Events, version 4.0. Results Median followup was 19.3 months. Two-year actuarial local control, regional control, and distant metastasis (DM) were 90%, 93%, and 23.6%, respectively. Two-year disease-free survival was 55%. Genitourinary, gastrointestinal, or gynecologic Grade 3 toxicity was seen in 5 patients (3 T4a and 2 T3b) for crude rates of 13%, 7%, and 3%, respectively. Stratifying HR-CTV by <30 and >30 cc and then by HR-CTV D 90 of <85, 85–90, and >90 Gy showed that 100% of the local failures, regional failures, DM, and G3 toxicity occurred in >30 cc group. The rate of DM was also significantly higher in the >30 cc group ( p = 0.036). Conclusions An interstitial approach can achieve excellent outcomes in cases where intracavitary and/or hybrid approaches are either not suitable or not available. [ABSTRACT FROM AUTHOR]

Abstract: Purpose/Objectives: To facilitate catheter spacing, implant stability, and patient comfort during multicatheter interstitial brachytherapy. Methods and Materials: Uniform and consistent spacing of multiple interstitial implant catheters can be difficult because individual catheters may become displaced during the course of treatment. The authors have developed a brachytherapy catheter fixation method using Jackson-Pratt (JP) drains that can be used within wounds to maintain catheter spacing or on the skin surface for applicator fixation. JP drains are threaded over the implant needles to space and stabilize the implant geometry. The needles are then replaced with the usual brachytherapy catheters. Results: Surgically directed (“open”) placement of implant catheters is less prone to displacement when a drain connects and spaces the catheters in the wound. Fixation on the skin surface can also be achieved with the JP drains, which make the friction buttons optional. The soft drain material helps avoid discomfort and pressure injury sometimes associated with hard plastic buttons. Small (10 French) round JP drains are suitable for breast, and head and neck sites and larger 7×10-mm flat JP drains for extremity sarcomas, abdominal, or thoracic tumors. Conclusions: The complex brachytherapy devices fashioned from widely available surgical drains effectively guide and maintain geometry for multicatheter interstitial implants. Stable implant geometry leads to more reliable implementation of brachytherapy dosimetry. Patient comfort is improved and soft tissue injury from hard-edged buttons is avoided. [Copyright &y& Elsevier]

This retrospective study compares high dose rate brachytherapy (HDR BT) monotherapy against HDR BT and external beam radiation therapy (EBRT), with and without androgen deprivation therapy (ADT), to determine non-inferiority of HDR BT alone in the treatment of unfavorable intermediate risk (UIR) prostate cancer. Data were obtained from two registries from 1991-present. 633 patients with UIR prostate cancer treated with HDR BT were included. Patients who received only HDR BT received 42-45Gy/6 fractions (fx) or 27 Gy/2 fx. For HDR BT+EBRT, the HDR dose was 20-24 Gy/2 fx, 24 Gy/4 fx, or 15 Gy/1 fx. EBRT patients received 45 Gy/25 fx to the prostate +/- pelvic nodal radiation. GU/GI toxicities were graded according to the Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Treatment group differences were assessed via two-sample T test or ANOVA, and associations between categorical variable and treatment group were assessed via chi-squared or Fisher's exact test. Time-to-event analyses were carried out to evaluate relationship between treatments and primary outcome variables. Five primary endpoints were used to assess freedom from biochemical recurrence (FFBC), freedom from distant metastasis (FFDM), freedom from local failure (FFLF), cancer specific survival (CSS), and overall survival (OS). Univariate analysis was conducted using the Kaplan-Meier method and log-rank test to the primary event. For multivariate analysis, Cox proportional hazard (Cox PH) regression and Fine & Gray competing risk regression were carried out to adjust for potential confounders. For toxicity analysis, the association between the incidence of post-treatment severe GU/GI toxicity reaction, denoted grade 3 or higher, and the treatment group was evaluated via chi-squared or Fisher's exact test. Statistical comparisons for HDR, HDR+EBRT-ADT, and HDR+EBRT+ADT are summarized in Table 1. From the Kaplan-Meier curves and log-rank tests, no differences between the three cohorts were identified in all five survival outcomes (FFBC, FFDM, FFLF, OS, CSS), with 5-year survival for HDR, HDR+EBRT-ADT, and HDR+EBRT+ADT FFBC 99%, 95%, and 94% respectively. Multivariate analysis with Cox PH regression showed no differences in FFBC, FFDM, OS, and CSS with addition of EBT alone, or addition of EBT with ADT. Fine and Gray competing regression showed no difference in outcome for HDR, HDR+EBRT-ADT, and HDR+EBRT+ADT with respect to FFBC, FFDM, and CSS. Performing the likelihood ratio test to both the Cox PH and Fine & Gray competing regression models resulted in no differences in all survival outcomes with stable fits between treatment and non-treatment groups. In comparing CTCAE toxicities between the HDR, HDR+EBRT-ADT, and HDR+EBRT+ADT cohorts, no statistically significant differences were identified in GI and GU toxicities when comparing post-treatment and baseline toxicities. No Grade 2 or 3 GI toxicities were identified in any of the groups, while 8% and 1% of HDR patients, 10% and 1% of HDR+EBRT-ADT patients, and 12% and 2% of HDR+EBRT+ADT patients experienced Grade 2 or 3 GU toxicities. The presence of grade 3 or higher GU toxicities between the three groups were not found to be significant (p=0.91). The results of this study demonstrate the non-inferiority of HDR BT treatment alone for UIR prostate cancer when compared to HDR+EBRT +/- ADT. The omission of EBRT, with or without ADT, can theoretically minimize occurrence of associated toxicities, although the data in this study do not demonstrate statistically significant differences likely due to the overall low frequency of toxicities reported. Given patients' often reluctance in undergoing multiple procedures, especially when faced with the side effect profile of ADT, these results illuminate a viable road for HDR BT monotherapy in effective and durable control of UIR disease. [ABSTRACT FROM AUTHOR]

We aim to develop an approach to minimize the total number of treatment catheters in HDR prostate brachytherapy while maintaining plan quality. In this study, we present a novel simultaneous dwell-time and 4-pi catheter angle optimization algorithm for HDR prostate treatment. Candidate catheter locations were generated in a grid across the prostate with 4-pi insertion angles. Clinically infeasible catheters that intersected the urethra or could not be inserted through a catheter placement template were excluded from optimization. Depending on patient anatomy, this resulted in on average 9 angles of insertion at each grid position and 680 average total candidate catheters per patient. Treatment optimization was performed for 14 retrospective patients using the fast-iterative shrinkage-thresholding algorithm (FISTA) with a group sparsity regularization to reduce the set of candidate catheters to the a fixed number, M, while simultaneously optimizing the treatment dwell times. Plans were created using M = N,N-1,⋯,N-6 catheters, where N is the number of catheters used in clinical treatment for each patient. Each plan was optimized separately and normalized to deliver a 15 Gy/fx dose to 95% of the prostate. The volumes of the rectum, urethra, and bladder receiving 75% of 15 Gy (V75%) were minimized and compared to the 4-pi N catheter plan metrics using paired t-tests. These metrics were also calculated for the clinically delivered plans for comparison. The optimized 4-pi catheter distributions take advantage of the increased angular degrees of freedom compared to the clinical angles of insertion. Table 1 shows the mean rectum, urethra, and bladder V75% for the clinically delivered plans (row 1) and the 4-pi optimized catheter plans with N, ⋯, N-6 catheters. p -values for paired t-test comparison with the 4-pi N catheter plans (row 2) are given and statistically significant results are marked with a *. The mean clinical plan rectum and bladder V75% are smaller than the optimized plans, while the mean clinical urethra V75% is larger (Table 1). However, only the difference in bladder V75% was found to be statistically significant. For the 4-pi selection plans, decreasing the number of treatment catheters increases the V75% for all OARs by a small but statistically significant magnitude (Table 1). Our deterministic planning framework can successfully optimize treatment dwell times and select optimal and clinically feasible catheter placements and angles of insertion for any target number of catheters, while maintaining comparable plan quality to clinical practice. Further, this method shows promise for reducing the number of necessary treatment catheters with minimal compromise to key OAR dose constraints. [ABSTRACT FROM AUTHOR]

Periodontitis is a common disease characterized by chronic inflammation and tissue destruction of gums. Human periodontal ligament stem cells (PDLSCs), derived from the periodontium, have stem cell properties similar to those of mesenchymal stem cells. PDLSCs possess not only the potential to differentiate into other tissues, but also immunomodulatory abilities. Macrophages play a critical role in periodontal disease, but little is known regarding the role of PDLSCs in macrophage modulation during inflammation. In this study, we investigated the effect of PDLSCs on the macrophage cell line. While the conditioned media from PDLSCs under normal culture conditions did not affect macrophage polarization, the lipopolysaccharide (LPS)-preconditioned PDLSCs induced significant changes in M1 polarization. Extracellular vesicles (EVs) isolated from the conditioned media of LPS-preconditioned PDLSCs induced strong M1 polarization of macrophages. Additionally, the M1 polarization was abolished by DNase I treatment of EVs. Therefore, the LPS-stimulated PDLSCs induce M1 polarization of macrophages through EVs, suggesting that the EVs from PDLSCs might be a potential therapeutic target for inflammation in the periodontium. [ABSTRACT FROM AUTHOR]

Purpose Given the limited data using an interstitial approach with 3D-based planning for definitive cervical cancer utilizing the GEC-ESTRO defined high-risk clinical target volume (HR-CTV), we reviewed our institutional experience of cervical cancer patients with HR-CTVs ≥ 30 cc to determine whether our clinical and toxicity outcomes are acceptable. Methods A retrospective review of 37 cervical cancer patients with high-risk clinical target volumes (HR-CTVs) ≥30 cc treated with interstitial image-guided brachytherapy (IS IGBT) was performed. All patients received external beam radiotherapy to a median dose of 45 Gy, followed by IS IGBT delivered in a single implant to a median dose of 6 Gy × 5 fractions. Median HR-CTV was 59 cc. A median HR-CTV D 90 of 87.44 Gy was achieved. Kaplan–Meier method was used to evaluate local control (LC), distant control, and overall survival (OS), with stratification by overall treatment time (OTT) ≤ 7 or >7 weeks. Results Median followup was 17 months. The estimated 2-year LC, distant control, and OS were 77.6% (confidence interval [CI]: 63.8–94.5%), 56.8% (CI: 41.3–78.1%), and 54.4% (CI: 39.4–75%), respectively. The 2-year LC for OTT ≤7 weeks and >7 weeks were 100% and 58.3%, respectively ( p = 0.026). The 2-year OS for OTT ≤7 weeks and >7 weeks were 77.8% and 38%, respectively ( p = 0.021). Discussions IS IGBT can achieve a high D 90 to the HR-CTV even in the setting of large-volume disease and results in a favorable LC and toxicity profile. OTT > 7 weeks is associated with significant decrease in LC and OS. Conclusions Efforts should be made to complete whole treatment within 7 weeks as this is associated with improved clinical outcomes. [ABSTRACT FROM AUTHOR]

Purpose To determine whether pretreatment 3T multiparametric MRI (mpMRI) staging impacts biochemical recurrence-free survival (BRFS) or distant metastasis-free survival (DMFS) for men with high-risk prostate cancer treated with combination high-dose-rate (HDR) brachytherapy and external beam radiation therapy (EBRT). Materials and Methods This institutional review board–approved retrospective study included a cohort of 37 men with high-risk prostate cancer treated with HDR brachytherapy and EBRT after 3T mpMRI. Kaplan–Meier analysis was used to evaluate whether mpMRI evidence of extracapsular extension or seminal vesicle invasion (SVI) resulted in differences in BRFS or DMFS. Pretreatment and treatment-related variables were evaluated for association with biochemical failure (Phoenix definition) and distant metastatic failure using univariate Cox regression analysis. Results The median prostate-specific antigen at diagnosis was 9 ng/mL (range 2–100). Biopsy Gleason score (bGS) was ≤8 in 38% and nine in 62%. Clinical T-category was T1-T2 in 89%, T3a in 8%, and T3b in 3%. With a median followup of 30.6 months, actuarial 3-year BRFS and DMFS were 76% and 86%, respectively. Kaplan-Meier analysis revealed that mpMRI evidence of extracapsular extension or SVI resulted in significantly higher rates of both biochemical recurrence and distant failure. Using Cox regression analysis, only mpMRI evidence of SVI vs. no SVI predicted for biochemical failure (hazard ratio 13.98, p = 0.0055). Conclusions For high-risk prostate cancer treated with combination HDR brachytherapy and EBRT, mpMRI evidence of SVI predicted for biochemical failure, whereas traditional pretreatment variables did not. Therefore, pretreatment 3T mpMRI appears useful for identifying men who may benefit from treatment intensification. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this American Brachytherapy Society task force is to present a literature review and patterns of care by a panel of experts for the management of vaginal recurrence of endometrial cancer. Methods and materials In 2016, the American Brachytherapy Society Board selected a panel of experts in gynecologic brachytherapy to update our current state of knowledge for managing vaginal recurrence of endometrial cancer. Practice patterns were evaluated via an online survey and clinical updates occurred through a combination of literature review and clinical experience and/or expertise. Results There are various retrospective series of patients treated with radiation for vaginal recurrence of endometrial cancer, which include a varied group of patients, multiple treatment techniques, and a range of total doses and demonstrate a wide scope of local control and overall survival outcomes. In the era of image-guided brachytherapy, high local control rates with low significant late-term morbidities can be achieved. Lower rates of local control and higher late-term toxicity are reported in the retreatment setting. In patients with no previous history of radiation treatment, external beam radiation therapy followed by brachytherapy boost should be used. There are varying practices with regard to the definition and appropriate doses of both the high-risk clinical target volume and the intermediate-risk clinical target volume in the setting of vaginal recurrence of endometrial cancer. There are limited data to provide appropriate dose constraints for some organs at risk with the majority of guidance taken from the definitive cervical cancer literature. Conclusions A summary of literature and expert practice patterns for patient selection, dose recommendations, and constraints are provided as guidance for practitioners. [ABSTRACT FROM AUTHOR]

Purpose Outcomes using high-dose-rate (HDR) brachytherapy monotherapy (without androgen deprivation therapy or external beam radiation therapy) for National Comprehensive Cancer Network–defined intermediate-risk (IR) patients are limited. We report our long-term data using HDR monotherapy for this patient population. Methods and Materials One-hundred ninety IR prostate cancer patients were treated 1996–2013 with HDR monotherapy. Biochemical prostate-specific antigen (PSA) failure was per the Phoenix definition. Acute and late genitourinary and gastrointestinal toxicities were graded according to Common Toxicity Criteria of Adverse Events, version 4. Kaplan–Meier (KM) biochemical progression-free survival (BPFS), cause-specific survival, and overall survival rates were calculated. Univariate analyses were performed to determine relationships with BPFS. The median patient age was 66 years (43–90), and the median initial PSA was 7.4 ng/mL. The Gleason score was ≤6 in 26%, 3 + 4 in 62%, and 4 + 3 in 12%. The median treatment BED 1.5 was 254 Gy; 83% of patients were treated with a dose of 7.25 Gy × six fractions delivered in two separate implants. Results With a median follow-up of 6.2 years, KM BPFS at 5/8 years was 97%/90%, cause-specific survival at 8 years was 100%, and overall survival at 5/8 years was 93%/88%. Late genitourinary toxicities were 36.3% Grade 1, 18.9% Grade 2, and 3.7% Grade 3. Late gastrointestinal toxicities were 6.3% Grade 1, 1.1% Grade 2, and no Grade ≥3. Of the patients with no sexual dysfunction before treatment, 68% maintained potency. Age, initial PSA, T stage, Gleason score, prostate volume, and percent positive cores did not correlate with BPFS. Stratifying by favorable vs. unfavorable IR groups did not affect BPFS. Conclusions HDR brachytherapy monotherapy represents a safe and highly effective treatment for IR prostate cancer patients with long-term follow-up. [ABSTRACT FROM AUTHOR]

Purpose Cost estimates through traditional hospital accounting systems are often arbitrary and ambiguous. We used time-driven activity-based costing (TDABC) to determine the true cost of low-dose-rate (LDR) and high-dose-rate (HDR) brachytherapy for prostate cancer and demonstrate opportunities for cost containment at an academic referral center. Methods and Materials We implemented TDABC for patients treated with I-125, preplanned LDR and computed tomography based HDR brachytherapy with two implants from initial consultation through 12-month followup. We constructed detailed process maps for provision of both HDR and LDR. Personnel, space, equipment, and material costs of each step were identified and used to derive capacity cost rates, defined as price per minute. Each capacity cost rate was then multiplied by the relevant process time and products were summed to determine total cost of care. Results The calculated cost to deliver HDR was greater than LDR by $2,668.86 ($9,538 vs. $6,869). The first and second HDR treatment day cost $3,999.67 and $3,955.67, whereas LDR was delivered on one treatment day and cost $3,887.55. The greatest overall cost driver for both LDR and HDR was personnel at 65.6% ($4,506.82) and 67.0% ($6,387.27) of the total cost. After personnel costs, disposable materials contributed the second most for LDR ($1,920.66, 28.0%) and for HDR ($2,295.94, 24.0%). Conclusions With TDABC, the true costs to deliver LDR and HDR from the health system perspective were derived. Analysis by physicians and hospital administrators regarding the cost of care afforded redesign opportunities including delivering HDR as one implant. Our work underscores the need to assess clinical outcomes to understand the true difference in value between these modalities. [ABSTRACT FROM AUTHOR]

Purpose There is a lack of prescriptive, practical information for those doing the work of commissioning high-dose-rate (HDR) gynecologic (GYN) treatment equipment. The purpose of this work is to develop a vendor-neutral, consensus-based, commissioning template to improve standardization of the commissioning process. Methods and Materials A series of commissioning procedures and tests specific to HDR GYN treatments were compiled within one institution. The list of procedures and tests was then sent to five external reviewers at clinics engaged in HDR GYN treatments. External reviewers were asked to ( 1 ) suggest deletions, additions, and improvements/modifications to descriptions, ( 2 ) link the procedures and tests to common, severe failure modes based on their effectiveness at mitigating those failure modes, and ( 3 ) rank the procedures and tests based on perceived level of importance. Results External reviewers suggested the addition of 14 procedures and tests. The final template consists of 67 procedures and tests. “Treatment process” and “staff training” sections were identified as mitigating the highest number of commonly reported failure modes. The mean perceived importance for all procedures and tests was 4.4 of 5, and the mean for each section ranged from 3.6 to 4.8. Sections of the template that were identified as mitigating the highest number of commonly reported failure modes were not assigned the highest perceived importance. Conclusion The commissioning template developed here provides a standardized approach to process and equipment commissioning. The discord between perceived importance and mitigation of the highest number of failure modes suggests that increased focus should be placed on procedures and tests in “treatment process” and “staff training” sections. [ABSTRACT FROM AUTHOR]

Purpose: High-dose-rate (HDR) brachytherapy was originally used with external beam radiation therapy (EBRT) to increase the dose to the prostate without injuring the bladder or rectum. Numerous studies have reported HDR brachytherapy is safe and effective. We adapted it for use without EBRT for cases not requiring lymph node treatment.Patients and Methods: We entered the patient demographics, disease characteristics, and treatment parameters into a prospective registry and serially added follow-up data for 448 men with low-risk (n=288) and intermediate-risk (n=160) prostate cancer treated from 1996 to 2009. Their median age was 64 years (range 42-90). The median prostate-specific antigen (PSA) level was 6.0 ng/mL (range 0.2-18.2). The Gleason score was ≤6 in 76% and 7 in 24%. The median dose was 43.5 Gy in 6 fractions. The clinical and biochemical disease control and survival rates were calculated. Adverse events were graded according to the Common Toxicity Criteria of Adverse Events.Results: The median follow-up period was 6.5 years (range 0.3-15.3). The actuarial 6- and 10-year PSA progression-free survival was 98.6% (95% confidence interval [CI] 96.9%-99.4%) and 97.8% (95% CI 95.5%-98.9%). Overall survival at 10 years was 76.7% (95% CI 69.9%-82.2%). The local control, distant metastasis-free survival, and cause-specific survival were 99.7% (95% CI 97.9%-99.9%), 98.9% (95% CI 96.3%-99.7%), and 99.1% (95% CI 95.8%-99.8%). T stage, initial PSA level, Gleason score, National Comprehensive Cancer Network risk group, patient age, and androgen deprivation therapy did not significantly correlate with disease control or survival. No late grade 3 to 4 rectal toxicities developed. Late grade 3 to 4 genitourinary toxicity occurred in 4.9% (grade 3 in 4.7%).Conclusions: HDR monotherapy is a safe and highly effective treatment of low- and intermediate-risk prostate cancer. [ABSTRACT FROM AUTHOR]

Purpose To determine the utility of ureteral stents in interstitial gynecological brachytherapy. Methods and Materials We reviewed 289 patients with cervix cancer treated with high-dose-rate interstitial brachytherapy who did not have pretreatment hydronephrosis to determine the relative incidence of benign ureteral strictures after treatment. We also did comparative dosimetry analysis in five cases of high-dose-rate brachytherapy. Bilateral ureteral stents were placed during the procedure. Three dosimetry plans were created to determine the impact of modifying clinical target volume (CTV) and applying ureteral dose constraints. In Plan 1, the ureters were contoured and excluded from the CTV and 120% dose constraints were applied. In Plan 2, the ureters were contoured and excluded, but no dose constraints were applied to the ureter. In Plan 3, the CTV was created as if the location of the ureters was unknown and then ureteral dose was determined. Results There were 11 ureteral strictures observed in 255 nonstented cases and 0 ureteral strictures in 34 stented cases. Plan 1 reduced the ureter dose (D 0.1cc ) by a median 22% (7.0–53.8%) compared with Plan 2 and by a median of 30.9% (12.3–65%). compared with Plan 3. Conclusions Placement of stents and ureteral dose constraints facilitates dosimetry and reduces the dose to ureters. Temporary ureteral stents prevent obstruction during interstitial gynecologic brachytherapy and allows the ureters to be addressed as an organ at risk. [ABSTRACT FROM AUTHOR]

The present review has been focused largely on the sex type differences in beef quality among heifers, cows, steers and bulls in various feeding environments. Genetic groups, feeding systems and gender are the major factors that change carcass characteristics and fatty acid profiles of cattle. Studies identified that heifer beef has super characteristics in eating quality and a better healthy composition in fatty acids than steer, cow and bull. Diet influences the variation of fatty acid profile; particularly the level of polyunsaturated fatty acids (PUFA) interacts with breed and sex. Animals finished in pasture systems were reported to show better ratios of PUFA/ saturated fatty acids and n-6/n-3. Carcasses of roughage-fed beef are lighter and have less marbling and lower quality grades but have higher cutability than carcasses of grain-fed bulls. Heifers and cows are reported to deposit more fat than steers and bulls. Among males, lower production of testosterone by steers favors more fat thickness compared with bulls. Marbling greatly varies among cattle belonging to different sexes, and particularly, females have genetic makeup that efficiently controls deposition. The current review identified that heifers can be a premium beef brand, while steer beef currently take a large part of market share across the world. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: To determine the utility of focal high-dose-rate brachytherapy for localized prostate cancer, we investigated the impact on target coverage and dose to organs at risk (OARs) with hemigland (HG) compared with whole-gland (WG) treatment. Methods and Materials: A total of 10 WG implants were used to generate 10 WG and 20 HG (left and right) treatment plans optimized with the inverse planning simulation annealing algorithm using Oncentra MasterPlan (Nucletron B.V., Veenendaal, The Netherlands). The standard distribution of 17–18 catheters designed for WG was used to generate HG plans. The same OARs namely bladder, rectum, and urethra contours and dose constraints were applied for HG and WG plans. The HG contour was a modification of the WG contour whereby the urethra divided the prostate into HGs. The prescription dose was 7.25 Gy×6. Evaluated dose parameters were target dose D 90, V 100, and V 150 and D 0.1 cc, D 1 cc, and D 2 cc to OARs. Results: The HG plans had a D 90, V 100, and V 150 to the HG target of 112%, 97.6%, and 33.8%, respectively. The WG plans had a D 90, V 100, and V 150 to the WG target of 108%, 98.8%, and 26.5%, respectively. The OAR D 2 cc doses were significantly lower in HG vs. WG plans: rectum (53.1% vs. 64.1%, p <0.0001), bladder (55.9% vs. 67.5%, p <0.0001), and urethra (69.3% vs. 95.2%, p <0.0001). Conclusions: In the present model, HG plans yielded a statistically significant decreased radiation dose to OARs and provided complete target coverage with a catheter array designed for WG coverage. The good dosimetry results obtained in this study support the feasibility of HG brachytherapy by using a subset of the WG catheter array. Catheter distribution and dosimetry refinements tailored to subtotal prostate brachytherapy should be explored to see if further improvements in dosimetry can be achieved. [Copyright &y& Elsevier]

Abstract: Purpose: A new platform for brachytherapy called electronic brachytherapy (EBT) has been developed, which uses a miniature X-ray source to generate low-energy radiation. A retrospective study of adverse events and clinical outcomes in patients treated with EBT to the vaginal cuff, either as monotherapy or in combination with external beam radiation therapy (EBRT), was conducted. Methods and Materials: Medical records were reviewed from 16 patients treated with postoperative EBT for endometrial (n =13) or cervical cancer (n =3) between February 2009 and November 2010. Patients received either intracavitary vaginal EBT alone or EBT in combination with EBRT. The radiobiologic effectiveness of EBT was assumed to be one. Results: Median follow-up was 20.5 months (range, 7–36 months). When EBT was used alone (n =5), the median dose per fraction, number of fractions, and total dose delivered were: 6Gy (range, 5.5–6.2Gy), 5 fractions (range, 5–6), and 30Gy (range, 30–34Gy), respectively. When EBT was combined with EBRT, the EBT component median dose per fraction, number of fractions, and total dose delivered were: 5Gy (range, 4.5–7Gy), 2 fractions (range, 2–4), and 14Gy (range, 9–20Gy), respectively. The median EBRT dose was 45Gy (range, 45–49.2Gy). Our local control rate, locoregional (pelvic) control rate, and overall survival rate were 94%, 94%, and 88%, respectively. Of the 16 patients, 4 patients reported Grade 2 or greater toxicity (25%); however, there were no Grade 4–5 adverse events. Gynecologic, genitourinary, and gastrointestinal adverse events accounted for 57% (n =4), 43% (n =3), and 0% (n =0) of all Grade 2 or greater side effects. No Grade 2 or higher toxicities were noted in patients treated with EBT alone. Conclusion: EBT is an acceptable means of delivering postoperative vaginal brachytherapy and appears comparable with other methods; as the sole method of treatment, the toxicity rates of EBT are low. [Copyright &y& Elsevier]

Purpose: We performed a dosimetry analysis to determine how well the goals for clinical target volume coverage, dose homogeneity, and normal tissue dose constraints were achieved with high-dose-rate (HDR) prostate brachytherapy. Methods and Materials: Cumulative dose-volume histograms for 208 consecutively treated HDR prostate brachytherapy implants were analyzed. Planning was based on ultrasound-guided catheter insertion and postoperative CT imaging; the contoured clinical target volume (CTV) was the prostate, a small margin, and the proximal seminal vesicles. Dosimetric parameters analyzed for the CTV were D90, V90, V100, V150, and V200. Dose to the urethra, bladder, bladder balloon, and rectum were evaluated by the dose to 0.1 cm3, 1 cm3, and 2 cm3 of each organ, expressed as a percentage of the prescribed dose. Analysis was stratified according to prostate size. Results: The mean prostate ultrasound volume was 38.7 ± 13.4 cm3 (range: 11.7-108.6 cm3). The mean CTV was 75.1 ± 20.6 cm3 (range: 33.4-156.5 cm3). The mean D90 was 109.2% ± 2.6% (range: 102.3%-118.4%). Ninety-three percent of observed D90 values were between 105 and 115%. The mean V90, V100, V150, and V200 were 99.9% ± 0.05%, 99.5% ± 0.8%, 25.4% ± 4.2%, and 7.8% ± 1.4%. The mean dose to 0.1 cm3, 1 cm3, and 2 cm3 for organs at risk were: Urethra: 107.3% ± 3.0%, 101.1% ± 14.6%, and 47.9% ± 34.8%; bladder wall: 79.5% ± 5.1%, 69.8% ± 4.9%, and 64.3% ± 5.0%; bladder balloon: 70.3% ± 6.8%, 59.1% ± 6.6%, and 52.3% ± 6.2%; rectum: 76.3% ± 2.5%, 70.2% ± 3.3%, and 66.3% ± 3.8%. There was no significant difference between D90 and V100 when stratified by prostate size. Conclusions: HDR brachytherapy allows the physician to consistently achieve complete prostate target coverage and maintain normal tissue dose constraints for organs at risk over a wide range of target volumes. [Copyright &y& Elsevier]