Anti-inflammatory effects of a methanol extract of Dictamnus dasycarpus Turcz. root bark on imiquimod-induced psoriasis.

BACKGROUND: The root bark of Dictamnus dasycarpus Turcz. has been successfully used for the treatment of inflammatory skin conditions such as eczema and pruritus. However, the anti-psoriatic effect of this plant has not until now been investigated. METHODS: The aim of this project was to investigate whether a methanol extract of Dictamnus dasycarpus Turcz. root bark (MEDD) can be used as a therapeutic agent for psoriasis in C57BL/6 mice model of imiquimod (IMQ)-induced psoriasis. IMQ and MEDD was applied to mouse skin continuously for 7 days. The skin phenotype and the levels of inflammatory cytokines, such as interferon (IFN)-γ and interleukin (IL)-17, were analyzed. The immune cell population was determined by flow cytometry, and STAT1 and 3 protein levels were measured. RESULTS: An alleviation of scaly skin phenotype, immune cell infiltration in the dermis, and epidermal hyperplasia was observed after daily MEDD treatment in the lesion-affected area. It was also found that MEDD reduced IL-17 cytokine levels decreased by 44.37% (p < 0.05), the number of IL-17-producing Th17 cells and γδT cells, and the size of the Th1 population secreting IFN-γ decreased by 45.98, 62.21, and 44.42%, respectively (p < 0.05), compared with the vehicle control group. STAT3 signals, associated with IL-17 are also reduced by MEDD. CONCLUSIONS: An anti-psoriatic effect of MEDD was observed, as determined by decreased skin inflammation, reduced number of inflammatory cytokines, and a smaller population of inflammatory cells. These results contribute to the validation of the use of MEDD in the treatment of psoriasis.

Clinically relevant investigation of flattening filter-free skin dose.

As flattening filter-free (FFF) photon beams become readily available for treat-ment delivery in techniques such as SBRT, thorough investigation of skin dose from FFF photon beams is necessary under clinically relevant conditions. Using a parallel-plate PTW Markus chamber placed in a custom water-equivalent phantom, surface-dose measurements were taken at 2 × 2, 3 × 3, 4 × 4, 6 × 6, 8 × 8, 10 × 10, 20 × 20, and 30 × 30 cm2 field sizes, at 80, 90, and 100 cm source-to-surface distances (SSDs), and with fields defined by jaws and multileaf collimator (MLC) using multiple beam energies (6X, 6XFFF, 10X, and 10XFFF). The same set of measurements was repeated with the chamber at a reference depth of 10cm. Each surface measurement was normalized by its corresponding reference depth measurement for analysis. The FFF surface doses at 100 cm SSD were higher than flattened surface doses by 45% at 2 × 2 cm2 to 13% at 20 × 20 cm2 for 6MV energy. These surface dose differences varied to a greater degree as energy increased, ranging from +63% at 2 × 2 cm2 to -2% at 20 × 20 cm2 for 10 MV. At small field sizes, higher energy increased FFF surface dose relative to flattened surface dose; while at larger field sizes, relative FFF surface dose was higher for lower energies. At both energies investigated, decreasing SSD caused a decrease in the ratios of FFF-to-flattened surface dose. Variability with SSD of FFF-to-flattened surface dose differences increased with field size and ranged from 0% to 6%. The field size at which FFF and flattened beams gave the same skin dose increased with decreasing beam energy. Surface dose was higher with MLC fields compared to jaw fields under most conditions, with the difference reaching its maximum at a field size between 4 × 4 cm2 and 6 × 6 cm2 for a given energy and SSD. This study conveyed the magnitude of surface dose in a clinically meaning-ful manner by reporting results normalized to 10 cm depth dose instead of depth of dose maximum.

Development of a novel remote-controlled and self-contained audiovisual-aided interactive system for immobilizing claustrophobic patients.

In radiotherapy, only a few immobilization systems, such as open-face mask and head mold with a bite plate, are available for claustrophobic patients with a certain degree of discomfort. The purpose of this study was to develop a remote-controlled and self-contained audiovisual (AV)-aided interactive system with the iPad mini with Retina display for intrafractional motion management in brain/H&N (head and neck) radiotherapy for claustrophobic patients. The self-contained, AV-aided interactive system utilized two tablet computers: one for AV-aided interactive guidance for the subject and the other for remote control by an operator. The tablet for audiovisual guidance traced the motion of a colored marker using the built-in front-facing camera, and the remote control tablet at the control room used infrastructure Wi-Fi networks for real-time communication with the other tablet. In the evaluation, a programmed QUASAR motion phantom was used to test the temporal and positional accuracy and resolution. Position data were also obtained from ten healthy volunteers with and without guidance to evaluate the reduction of intrafractional head motion in simulations of a claustrophobic brain or H&N case. In the phantom study, the temporal and positional resolution was 24 Hz and 0.2 mm. In the volunteer study, the average superior-inferior and right-left displacement was reduced from 1.9 mm to 0.3 mm and from 2.2 mm to 0.2 mm with AV-aided interactive guidance, respectively. The superior-inferior and right-left positional drift was reduced from 0.5 mm/min to 0.1 mm/min and from 0.4 mm/min to 0.04 mm/min with audiovisual-aided interactive guidance. This study demonstrated a reduction in intrafractional head motion using a remote-controlled and self-contained AV-aided interactive system of iPad minis with Retina display, easily obtainable and cost-effective tablet computers. This approach can potentially streamline clinical flow for claustrophobic patients without a head mask and also allows patients to practice self-motion management before radiation treatment delivery.

Motion management within two respiratory-gating windows: feasibility study of dual quasi-breath-hold technique in gated medical procedures.

A dual quasi-breath-hold (DQBH) technique is proposed for respiratory motion management (a hybrid technique combining breathing-guidance with breath-hold task in the middle). The aim of this study is to test a hypothesis that the DQBH biofeedback system improves both the capability of motion management and delivery efficiency. Fifteen healthy human subjects were recruited for two respiratory motion measurements (free breathing and DQBH biofeedback breathing for 15 min). In this study, the DQBH biofeedback system utilized the abdominal position obtained using an real-time position management (RPM) system (Varian Medical Systems, Palo Alto, USA) to audio-visually guide a human subject for 4 s breath-hold at EOI and 90% EOE (EOE90%) to improve delivery efficiency. We investigated the residual respiratory motion and the delivery efficiency (duty-cycle) of abdominal displacement within the gating window. The improvement of the abdominal motion reproducibility was evaluated in terms of cycle-to-cycle displacement variability, respiratory period and baseline drift. The DQBH biofeedback system improved the abdominal motion management capability compared to that with free breathing. With a phase based gating (mean ± std: 55 ± 5%), the averaged root mean square error (RMSE) of the abdominal displacement in the dual-gating windows decreased from 2.26 mm of free breathing to 1.16 mm of DQBH biofeedback (p-value = 0.007). The averaged RMSE of abdominal displacement over the entire respiratory cycles reduced from 2.23 mm of free breathing to 1.39 mm of DQBH biofeedback breathing in the dual-gating windows (p-value = 0.028). The averaged baseline drift dropped from 0.9 mm min(-1) with free breathing to 0.09 mm min(-1) with DQBH biofeedback (p-value = 0.048). The averaged duty-cycle with an 1 mm width of displacement bound increased from 15% of free breathing to 26% of DQBH biofeedback (p-value = 0.003). The study demonstrated that the DQBH biofeedback system has the potential to significantly reduce the residual respiratory motion with the improved duty cycle during the respiratory gating procedure.

Dosimetric perturbations due to an implanted cardiac pacemaker in MammoSite(®) treatment.

PURPOSE: To investigate dose perturbations for pacemaker-implanted patients in partial breast irradiation using high dose rate (HDR) balloon brachytherapy. METHODS: Monte Carlo (MC) simulations were performed to calculate dose distributions involving a pacemaker in Ir-192 HDR balloon brachytherapy. Dose perturbations by varying balloon-to-pacemaker distances (BPD = 50 or 100 mm) and concentrations of iodine contrast medium (2.5%, 5.0%, 7.5%, and 10.0% by volume) in the balloon were investigated for separate parts of the pacemaker (i.e., battery and substrate). Relative measurements using an ion-chamber were also performed to confirm MC results. RESULTS: The MC and measured results in homogeneous media without a pacemaker agreed with published data within 2% from the balloon surface to 100 mm BPD. Further their dose distributions with a pacemaker were in a comparable agreement. The MC results showed that doses over the battery were increased by a factor of 3, compared to doses without a pacemaker. However, there was no significant dose perturbation in the middle of substrate but up to 70% dose increase in the substrate interface with the titanium capsule. The attenuation by iodine contrast medium lessened doses delivered to the pacemaker by up to 9%. CONCLUSIONS: Due to inhomogeneity of pacemaker and contrast medium as well as low-energy photons in Ir-192 HDR balloon brachytherapy, the actual dose received in a pacemaker is different from the homogeneous medium-based dose and the external beam-based dose. Therefore, the dose perturbations should be considered for pacemaker-implanted patients when evaluating a safe clinical distance between the balloon and pacemaker.