Fast skin dose estimation system for interventional radiology

PubMed Central

Takata, Takeshi; Kotoku, Jun’ichi; Maejima, Hideyuki; Kumagai, Shinobu; Arai, Norikazu; Kobayashi, Takenori; Shiraishi, Kenshiro; Yamamoto, Masayoshi; Kondo, Hiroshi; Furui, Shigeru

2018-01-01

Abstract To minimise the radiation dermatitis related to interventional radiology (IR), rapid and accurate dose estimation has been sought for all procedures. We propose a technique for estimating the patient skin dose rapidly and accurately using Monte Carlo (MC) simulation with a graphical processing unit (GPU, GTX 1080; Nvidia Corp.). The skin dose distribution is simulated based on an individual patient’s computed tomography (CT) dataset for fluoroscopic conditions after the CT dataset has been segmented into air, water and bone based on pixel values. The skin is assumed to be one layer at the outer surface of the body. Fluoroscopic conditions are obtained from a log file of a fluoroscopic examination. Estimating the absorbed skin dose distribution requires calibration of the dose simulated by our system. For this purpose, a linear function was used to approximate the relation between the simulated dose and the measured dose using radiophotoluminescence (RPL) glass dosimeters in a water-equivalent phantom. Differences of maximum skin dose between our system and the Particle and Heavy Ion Transport code System (PHITS) were as high as 6.1%. The relative statistical error (2 σ) for the simulated dose obtained using our system was ≤3.5%. Using a GPU, the simulation on the chest CT dataset aiming at the heart was within 3.49 s on average: the GPU is 122 times faster than a CPU (Core i7–7700K; Intel Corp.). Our system (using the GPU, the log file, and the CT dataset) estimated the skin dose more rapidly and more accurately than conventional methods. PMID:29136194

Fast skin dose estimation system for interventional radiology.

PubMed

Takata, Takeshi; Kotoku, Jun'ichi; Maejima, Hideyuki; Kumagai, Shinobu; Arai, Norikazu; Kobayashi, Takenori; Shiraishi, Kenshiro; Yamamoto, Masayoshi; Kondo, Hiroshi; Furui, Shigeru

2018-03-01

To minimise the radiation dermatitis related to interventional radiology (IR), rapid and accurate dose estimation has been sought for all procedures. We propose a technique for estimating the patient skin dose rapidly and accurately using Monte Carlo (MC) simulation with a graphical processing unit (GPU, GTX 1080; Nvidia Corp.). The skin dose distribution is simulated based on an individual patient's computed tomography (CT) dataset for fluoroscopic conditions after the CT dataset has been segmented into air, water and bone based on pixel values. The skin is assumed to be one layer at the outer surface of the body. Fluoroscopic conditions are obtained from a log file of a fluoroscopic examination. Estimating the absorbed skin dose distribution requires calibration of the dose simulated by our system. For this purpose, a linear function was used to approximate the relation between the simulated dose and the measured dose using radiophotoluminescence (RPL) glass dosimeters in a water-equivalent phantom. Differences of maximum skin dose between our system and the Particle and Heavy Ion Transport code System (PHITS) were as high as 6.1%. The relative statistical error (2 σ) for the simulated dose obtained using our system was ≤3.5%. Using a GPU, the simulation on the chest CT dataset aiming at the heart was within 3.49 s on average: the GPU is 122 times faster than a CPU (Core i7-7700K; Intel Corp.). Our system (using the GPU, the log file, and the CT dataset) estimated the skin dose more rapidly and more accurately than conventional methods.

SU-G-201-14: Is Maximum Skin Dose a Reliable Metric for Accelerated Partial Breast Irradiation with Brachytherapy?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, S; Ragab, O; Patel, S

Purpose: To evaluate the reliability of the maximum point dose (Dmax) to the skin surface as a dosimetric constraint, we investigated the correlation between Dmax at the skin surface and dose metrics at various definitions of skin thickness. Methods: 42 patients treated with APBI using a Strut Adjusted Volume Implant (SAVI) applicator between 2010 and 2014 were retrospectively reviewed. Target (PTV-EVAL) and organs at risk (OARs: skin, lung, and ribs) were delineated on a CT following NSABP B-39 guidelines. Six skin structures were contoured: a rind 3cm external to the body surface and 1, 2, 3, 4, and 5mm thickmore » rinds deep to the body surface. Inverse planning simulated annealing optimization was used to deliver 32–34Gy in 8-10 fractions to the target while minimizing OAR doses. Dmax, D0.1cc, D1.0cc, and D2.0cc to the various skin structures were calculated. Linear regressions between the metrics were evaluated using the coefficient of determination (R{sup 2}). Results: The average±SD PTV-EVAL volume and cavity-to-skin distances were 71.1±28.5cc and 6.9±5.0mm. The target V90 and V95 were 97.3±2.3% and 95.1±3.2%. The Dmax to the skin structures were 78.7±10.2% (skin surface), 82.2±10.7% (skin-1mm), 89.4±12.6% (skin-2mm), 97.9±15.4% (skin-3mm), 114.1±32.5% (skin-4mm), and 157.0±85.3% (skin-5mm). Linear regression analysis showed D1.0cc and D2.0cc to the skin 1mm and Dmax to the skin-4mm and 5mm were poorly correlated with other metrics (R{sup 2}=0.413±0.204). Dmax to the skin surface was well correlated (R{sup 2}=0.910±0.047) and D1.0cc to the skin-3mm was strongly correlated with all subsurface skin layers (R{sup 2}=0.935±0.050). Conclusion: Dmax to the skin surface is a relevant metric for breast skin dose. Contouring discontinuities in the skin with a 1mm subsurface rind and the active dwells in the skin 4 and 5mm introduced significant variations in skin DVH. D0.1cc, D1.0cc, and D2.0cc to a 3mm skin rind are more robust metrics in breast brachytherapy.« less

Main clinical, therapeutic and technical factors related to patient's maximum skin dose in interventional cardiology procedures

PubMed Central

Journy, N; Sinno-Tellier, S; Maccia, C; Le Tertre, A; Pirard, P; Pagès, P; Eilstein, D; Donadieu, J; Bar, O

2012-01-01

Objective The study aimed to characterise the factors related to the X-ray dose delivered to the patient's skin during interventional cardiology procedures. Methods We studied 177 coronary angiographies (CAs) and/or percutaneous transluminal coronary angioplasties (PTCAs) carried out in a French clinic on the same radiography table. The clinical and therapeutic characteristics, and the technical parameters of the procedures, were collected. The dose area product (DAP) and the maximum skin dose (MSD) were measured by an ionisation chamber (Diamentor; Philips, Amsterdam, The Netherlands) and radiosensitive film (Gafchromic; International Specialty Products Advanced Materials Group, Wayne, NJ). Multivariate analyses were used to assess the effects of the factors of interest on dose. Results The mean MSD and DAP were respectively 389 mGy and 65 Gy cm−2 for CAs, and 916 mGy and 69 Gy cm−2 for PTCAs. For 8% of the procedures, the MSD exceeded 2 Gy. Although a linear relationship between the MSD and the DAP was observed for CAs (r=0.93), a simple extrapolation of such a model to PTCAs would lead to an inadequate assessment of the risk, especially for the highest dose values. For PTCAs, the body mass index, the therapeutic complexity, the fluoroscopy time and the number of cine frames were independent explanatory factors of the MSD, whoever the practitioner was. Moreover, the effect of technical factors such as collimation, cinematography settings and X-ray tube orientations on the DAP was shown. Conclusion Optimising the technical options for interventional procedures and training staff on radiation protection might notably reduce the dose and ultimately avoid patient skin lesions. PMID:22457404

MO-D-213-04: The Proximity to the Skin of PTV Affects PTV Coverage and Skin Dose for TomoTherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reynolds, T; Higgins, P; Watanabe, Y

Purpose: The proximity to the skin surface of the PTV for the patients with skin disease could be a concern in terms of the PTV coverage and actual surface dose (SD). IMRT optimization algorithms increase the beam intensity close to the skin in order to compensate for lack of scattering material, leading to enhanced SD but potential hot spots. This study aims to investigate the effect of PTV proximity to the skin on planning and measured SD Methods: All measurements were done for 6 MV X-ray beam of Helical TomoTherapy. An anthropomorphic phantom was scanned in a CT simulator inmore » a routine manner with thermoplastic mask immobilization. PTVs were created with varying distances to the skin of 0 mm -(PTV1), 1 mm- (PTV2), 2 mm-(PTV3) and 3 mm-(PTV4). Also, a 5 mm bolus was used with PTV1 (PTV5). All planning constraints were kept the same in all studies (hard constraint: 95% of the prescription dose covered 95% of the PTV). Gafchromic film (EBT3) was placed under the mask on the phantom surface, and the resulting dose was estimated using RIT software. Results: Optimizing the dose using different PTVs lead to average planned target doses of 10.8, 10.3, 10.2, 10.3 and 10.0 Gy, with maximum doses 12.2, 11.2, 11.1, 11.1 and 10.0 Gy for PTV1, PTV2, PTV3, PTV4 and PTV5, respectively. EBT3 measurements indicated a significant decrease of SD with skin distance by 12.7% (PTV1), 21.9% (PTV2), 24.8% (PTV3) and 28.4% (PTV4) comparing to prescription dose. Placement of a 5 mm bolus on the phantom surface resulted in a SD close to prescribed (+0.5%). Conclusion: This work provides a clear demonstration of the relationship between the skin dose and the PTV to the skin distance. The results indicate the necessity of a bolus even for TomoTherapy when high skin dose is required.« less

Measurement of 238U and 232Th in Petrol, Gas-oil and Lubricant Samples by Using Nuclear Track Detectors and Resulting Radiation Doses to the Skin of Mechanic Workers.

PubMed

Misdaq, M A; Chaouqi, A; Ouguidi, J; Touti, R; Mortassim, A

2015-10-01

Workers in repair shops of vehicles (cars, buses, truck, etc.) clean carburetors, check fuel distribution, and perform oil changes and greasing. To explore the exposure pathway of (238)U and (232)Th and its decay products to the skin of mechanic workers, these radionuclides were measured inside petrol, gas-oil, and lubricant material samples by means of CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs), and corresponding annual committed equivalent doses to skin were determined. The maximum total equivalent effective dose to skin due to the (238)U and (232)Th series from the application of different petrol, gas-oil, and lubricant samples by mechanic workers was found equal to 1.2 mSv y(-1) cm(-2).

Comparison of intensity-modulated radiotherapy and volumetric-modulated arc therapy dose measurement for head and neck cancer using optical stimulated luminescence dosimeter

NASA Astrophysics Data System (ADS)

Lai, Lu-Han; Chuang, Keh-Shih; Lin, Hsin-Hon; Liu, Yi-Chi; Kuo, Chiung-Wen; Lin, Jao-Perng

2017-11-01

The in-vivo dose distributions of intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT), a newly developed technique, for head and neck cancer have been investigated for several years. The present study used a head-and-neck RANDO phantom to simulate the clinical conditions of nasopharyngeal carcinoma and compare the radiation doses between VMAT and IMRT. Three types of planning target volume (PTV) profiles were targeted by reducing the PTV surface margin by 0, 3, and 5 mm. An optically stimulated luminescence dosimeter was used to measure the surface doses. The results revealed that VMAT provided on average 16.8-13.8% lower surface doses within the PTV target areas than IMRT. When the PTV margin was reduced by 0 mm, the surface doses for IMRT reached their maximum value, accounting for 75.1% of its prescribed dose (Dp); however, the Dp value of VMAT was only 61.1%. When the PTV margin was reduced by 3 or 5 mm, the surface doses decreased considerably. The observed surface doses were insufficient when the tumours invaded the body surface; however, VMAT exerted larger skin-sparing effects than IMRT when the tumours away from the skin. These results suggest that the skin doses for these two techniques are insufficient for surface tumours. Notably, VMAT can provide lower skin doses for deep tumours.

Skin dose differences between intensity-modulated radiation therapy and volumetric-modulated arc therapy and between boost and integrated treatment regimens for treating head and neck and other cancer sites in patients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Penoncello, Gregory P.; Ding, George X., E-mail: george.ding@vanderbilt.edu

The purpose of this study was (1) to evaluate dose to skin between volumetric-modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT) treatment techniques for target sites in the head and neck, pelvis, and brain and (2) to determine if the treatment dose and fractionation regimen affect the skin dose between traditional sequential boost and integrated boost regimens for patients with head and neck cancer. A total of 19 patients and 48 plans were evaluated. The Eclipse (v11) treatment planning system was used to plan therapy in 9 patients with head and neck cancer, 5 patients with prostate cancer, andmore » 5 patients with brain cancer with VMAT and static-field IMRT. The mean skin dose and the maximum dose to a contiguous volume of 2 cm{sup 3} for head and neck plans and brain plans and a contiguous volume of 5 cm{sup 3} for pelvis plans were compared for each treatment technique. Of the 9 patients with head and neck cancer, 3 underwent an integrated boost regimen. One integrated boost plan was replanned with IMRT and VMAT using a traditional boost regimen. For target sites located in the head and neck, VMAT reduced the mean dose and contiguous hot spot most noticeably in the shoulder region by 5.6% and 5.4%, respectively. When using an integrated boost regimen, the contiguous hot spot skin dose in the shoulder was larger on average than a traditional boost pattern by 26.5% and the mean skin dose was larger by 1.7%. VMAT techniques largely decrease the contiguous hot spot in the skin in the pelvis by an average of 36% compared with IMRT. For the same target coverage, VMAT can reduce the skin dose in all the regions of the body, but more noticeably in the shoulders in patients with head and neck and pelvis cancer. We also found that using integrated boost regimens in patients with head and neck cancer leads to higher shoulder skin doses compared with traditional boost regimens.« less

The radiation dose from a proposed measurement of arsenic and selenium in human skin

NASA Astrophysics Data System (ADS)

Gherase, Mihai R.; Mader, Joanna E.; Fleming, David E. B.

2010-09-01

Dose measurements following 10 min irradiations with a portable x-ray fluorescence spectrometer composed of a miniature x-ray tube and a silicon PiN diode detector were performed using thermoluminescent dosimeters consisting of LiF:Mg,Ti chips of 3 mm diameter and 0.4 mm thickness. The table-top setup of the spectrometer was used for all measurements. The setup included a stainless steel lid which served as a radiation shield. Two rectangular polyethylene skin/soft tissue phantoms with two cylindrical plaster of Paris bone phantoms were used to study the effect of x-ray beam attenuation and backscatter on the measured dose. Eight different irradiation experiments were performed. The average dose rate values measured with TLD chips within a 1 × 1 cm2 area were between 4.8 and 12.8 mGy min-1. The equivalent dose for a 1 × 1 cm2 skin area was estimated to be 13.2 mSv. The maximum measured dose rate values with a single TLD chip were between 7.5 and 25.1 mGy min-1. The effective dose corresponding to a proposed arsenic/selenium skin measurement was estimated to be 0.13 µSv for a 2 min irradiation.

SU-E-P-14: Dosimetric Effects of Magnetic Field in MRI-Guided Radiation Therapy Delivery for Breast Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, G; Currey, A; Li, X

2015-06-15

Purpose: MRI-guided radiation therapy (RT) delivery would be beneficial for breast irradiation. The electron return effect due to the presence of a transverse magnetic field (TMF) may cause dosimetric issues on dose on skin and at the lung-tissue interface. The purpose of this study is to investigate these issues. Methods: IMRT plans with tangential beams and VMAT plans with 200 degree arcs to cover ipsilateral breast were generated for 10 randomly selected breast cancer cases using a research planning system (Monaco, Elekta) utilizing Monte Carlo dose calculation with or without a TMF of 1.5 T. Plans were optimized to delivermore » uniform dose to the whole breast with an exclusion of 5 mm tissue under the skin (PTV-EVAL). All four plans for each patient were re-scaled to have the same PTV-EVAL volume to receive the same prescription dose. The skin is defined as the first 5 mm of ipsilateral-breast tissue, plus extensions in the surrounding region. Results: The presence of 1.5 T TMF resulted in (1)increased skin dose, with the mean and maximum skin dose increase of 5% and 9%, respectively; (2) similar dose homogeneity within the PTV-EVAL; (3) the slightly improved (3%) dose homogeneity in the whole breast; (4) Averages of 9 and 16% increases in V5 and V20, respectively, for ipsilateral lung; and (5) increased the mean heart dose by 34%. VMAT plans don’t improve whole breast dose uniformity as compared that to the tangential plans. Conclusion: The presence of transverse magnetic field in MRI-guided RT delivery for whole breast irradiation can Result in slightly improved dose homogeneity in the whole breast, increased dose to the ipsilateral lung, heart, and skin. Plan optimization with additional specific dose volume constraints may eliminate/reduce these dose increases. This work is partially supported by Elekta Inc.« less

Skin dose measurement by using ultra-thin TLDs.

PubMed

Lin, J P; Chu, T C; Lin, S Y; Liu, M T

2001-09-01

The treatment schedule for radiation therapy is often interrupted because of complicated skin reactions. Quantitative information relating beam parameters and skin reactions will be helpful. Measurements were performed for 6-15 MV photons and 6-21 MeV electrons with ultra thin TLD films (GR-200F, surface area 0.5 x 0.5cm2, nominal thickness 5 mg cm(-2)). The skin doses for various field sizes, ranging from 10 x 10 to 40 x 40 cm2, and various incident angles of beam from 0 degrees to 80 degrees were measured. The ratios of skin dose to maximum dose in phantom for 10 x 10 cm2 are 16.10+/-0.68%, 14.03+/-1.04% and 10.59+/-0.64% for 6, 10 and 15 MV, respectively. Such ratios increase with a larger field size. For electrons the ratios are 72.59+/-1.72%, 78.52+/-2.99%, 78.89+/-2.86%, 86.08+/-2.62%. 87.75+/-1.94% and 86.33+/-3.09% for 6, 9, 12, 15, 18 and 21 MeV, respectively. They also increase with a larger size. The oblique factors also increase with larger incident angle.

Skin color and tissue thickness effects on transmittance, reflectance, and skin temperature when using 635 and 808 nm lasers in low intensity therapeutics.

PubMed

Souza-Barros, Leanna; Dhaidan, Ghaith; Maunula, Mikko; Solomon, Vaeda; Gabison, Sharon; Lilge, Lothar; Nussbaum, Ethne L

2018-04-01

To examine the role of skin color and tissue thickness on transmittance, reflectance, and skin heating using red and infrared laser light. Forty volunteers were measured for skin color and skin-fold thickness at a standardized site near the elbow. Transmittance, reflectance and skin temperature were recorded for energy doses of 2, 6, 9, and 12 Joules using 635 nm (36 mW) and 808 nm (40 mW) wavelength laser diodes with irradiances within American National Standards Institute safety guidelines (4.88 mm diameter, 0.192 W/cm 2 and 4.88 mm diameter, 0.214 W/cm 2 , respectively). The key factors affecting reflectance to an important degree were skin color and wavelength. However, the skin color effects were different for the two wavelengths: reflectance decreased for darker skin with a greater decrease for red light than near infrared light. Transmittance was greater using 808 nm compared with 635 nm. However, the effect was partly lost when the skin was dark rather than light, and was increasingly lost as tissue thickness increased. Dose had an increasing effect on temperature (0.7-1.6°C across the 6, 9, and 12 J doses); any effects of wavelength, skin color, and tissue thickness were insignificant compared to dose effects. Subjects themselves were not aware of the increased skin temperature. Transmittance and reflectance changes as a function of energy were very small and likely of no clinical significance. Absorption did not change with higher energy doses and increasing temperature. Skin color and skin thickness affect transmittance and reflectance of laser light and must be accounted for when selecting energy dose to ensure therapeutic effectiveness at the target tissue. Skin heating appears not to be a concern when using 635 and 808 nm lasers at energy doses of up to 12 J and irradiance within American National Standards Institute standards. Photobiomodulation therapy should never exceed the American National Standards Institute recommendation for the maximum permissible exposure to the skin. Lasers Surg. Med. 50:291-301, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Characterization of a new MOSFET detector configuration for in vivo skin dosimetry.

PubMed

Scalchi, Paolo; Francescon, Paolo; Rajaguru, Priyadarshini

2005-06-01

The dose released to the patient skin during a radiotherapy treatment is important when the skin is an organ at risk, or on the contrary, is included in the target volume. Since most treatment planning programs do not predict dose within several millimeters of the body surface, it is important to have a method to verify the skin dose for the patient who is undergoing radiotherapy. A special type of metal oxide semiconductors field-effect transistors (MOSFET) was developed to perform in vivo skin dosimetry for radiotherapy treatments. Water-equivalent depth (WED), both manufacturing and sensor reproducibility, dependence on both field size and angulation of the sensor were investigated using 6 MV photon beams. Patient skin dosimetries were performed during 6 MV total body irradiations (TBI). The resulting WEDs ranged from 0.04 and 0.15 mm (0.09 mm on average). The reproducibility of the sensor response, for doses of 50 cGy, was within +/-2% (maximum deviation) and improves with increasing sensitivity or dose level. As to the manufacturing reproducibility, it was found to be +/-0.055 mm. No WED dependence on the field size was verified, but possible variations of this quantity with the field size could be hidden by the assessment uncertainty. The angular dependence, for both phantom-surface and in-air setups, when referred to the mean response, is within +/-27% until 80 degree rotations. The results of the performed patient skin dosimetries showed that, normally, our TBI setup was suitable to give skin the prescribed dose, but, for some cases, interventions were necessary: as a consequence the TBI setup was corrected. The water-equivalent depth is, on average, less than the thinnest thermoluminescent dosimeters (TLD). In addition, when compared with TLDs, the skin MOSFETs have significant advantages, like immediate both readout and reuse, as well as the permanent storage of dose. These sensors are also waterproof. The in vivo dosimetries performed prove the importance of verifying the dose to the skin of the patient undergoing radiotherapy.

Effects of radioactive hot particles on pig skin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaurin, D.G.; Baum, J.W.; Schaefer, C.W.

1997-06-01

The purpose of these studies was to determine the incidence and severity of lesions resulting from very localized deposition of dose to skin from small (< 0.5 mm) discrete radioactive particles as produced in the work environments of nuclear reactors. Hanford mini-pigs were exposed, both on a slightly off the skin, to localized replicate doses from 0.31 to 64 Gy (averaged over 1 cm{sup 2} at 70 {mu}m depth unless noted otherwise) using Sc-46, Yb-175, Tm-170, and fissioned UC{sub 2} isotopes having maximum beta-particle energies from about 0.3 to 3 MeV. Erythema and scabs (indicating ulceration) were scored for upmore » to 71 days post-irradiation. The responses followed normal cumulative probability distributions, and therefore, no true threshold could be defined. Hence, 10 and 50% scab incidence rates were deduced using probit analyses. The lowest dose which produced 10% incidence was about 1 Gy for Yb-175 (0.5 MeV maximum energy) beta particle exposures, and about 3 to 9 Gy for other isotopes. The histopathology of lesions was determined at several doses. Single exposures to doses as large as 1,790 Gy were also given, and results were observed for up to 144 days post-exposure. Severity of detriment was estimated by analyzing the results in terms of lesion diameter, persistence, and infection. Over 1,100 sites were exposed. Only two exposed sites became infected after doses near 5000 Gy; the lesions healed quickly on treatment. 105 refs., 145 figs., 47 tabs.« less

Skin dose differences between intensity-modulated radiation therapy and volumetric-modulated arc therapy and between boost and integrated treatment regimens for treating head and neck and other cancer sites in patients.

PubMed

Penoncello, Gregory P; Ding, George X

2016-01-01

The purpose of this study was (1) to evaluate dose to skin between volumetric-modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT) treatment techniques for target sites in the head and neck, pelvis, and brain and (2) to determine if the treatment dose and fractionation regimen affect the skin dose between traditional sequential boost and integrated boost regimens for patients with head and neck cancer. A total of 19 patients and 48 plans were evaluated. The Eclipse (v11) treatment planning system was used to plan therapy in 9 patients with head and neck cancer, 5 patients with prostate cancer, and 5 patients with brain cancer with VMAT and static-field IMRT. The mean skin dose and the maximum dose to a contiguous volume of 2cm(3) for head and neck plans and brain plans and a contiguous volume of 5cm(3) for pelvis plans were compared for each treatment technique. Of the 9 patients with head and neck cancer, 3 underwent an integrated boost regimen. One integrated boost plan was replanned with IMRT and VMAT using a traditional boost regimen. For target sites located in the head and neck, VMAT reduced the mean dose and contiguous hot spot most noticeably in the shoulder region by 5.6% and 5.4%, respectively. When using an integrated boost regimen, the contiguous hot spot skin dose in the shoulder was larger on average than a traditional boost pattern by 26.5% and the mean skin dose was larger by 1.7%. VMAT techniques largely decrease the contiguous hot spot in the skin in the pelvis by an average of 36% compared with IMRT. For the same target coverage, VMAT can reduce the skin dose in all the regions of the body, but more noticeably in the shoulders in patients with head and neck and pelvis cancer. We also found that using integrated boost regimens in patients with head and neck cancer leads to higher shoulder skin doses compared with traditional boost regimens. Copyright © 2016 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Study of the effect of temperature on the optical properties of Latin skins

NASA Astrophysics Data System (ADS)

Quistián-Vázquez, Brenda; Morales-Cruzado, Beatriz; Sarmiento-Gómez, Erick; Pérez-Gutiérrez, Francisco G.

2017-02-01

Photodynamic therapy (PDT) is a very effective technique for treatment of certain types of cancer, among the most common, skin cancer. PDT requires the presence of three elements: the photosensitizer, light and oxygen. Penetration depth of light into the tumor depends on both the characteristics of the tissue to be treated and the wavelength. As the light dose to be delivered in each lesion depends on the optical properties of the tissue, all the effects that change these properties should be considered in order to choose suitable doses. There are some studies that have determined the maximum dose of radiation tolerated for certain types of skin, but the influence of the temperature on the optical properties, especially for darker skin types, remains unknown. In this study, we analyzed the optical properties of skin in vivo of different Latin volunteers in order to study the influence of the temperature on the optical properties and thereby to define more precisely the dose of light to be received by each patient in a personalized way. The optical properties of skin in vivo were investigated using an optical system that included an integrating sphere, a tungsten lamp and a spectrophotometer. Such experimental set up-allowed to obtain spectra reflectance of various volunteers and from this measurement, the absorption coefficient was recovered by Inverse Adding Doubling (IAD) program.

SU-F-BRB-14: Dosimetric Effects at Air- Tissue Boundary Due to Magnetic Field in MR-Guided IMRT/VMAT Delivery for Head and Neck Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prior, P; Chen, X; Schultz, C

Purpose: The advent of the MR-Linac enables real-time and high soft tissue contrast image guidance in radiation therapy (RT) delivery. Potential hot-spots at air-tissue interfaces, such as the sphenoid sinus, in RT for head and neck cancer (HNC), could potentially occur due to the electron return effect (ERE). In this study, we investigate the dosimetric effects of ERE on the dose distribution at air-tissues interfaces in HNC IMRT treatment planning. Methods: IMRT plans were generated based on planning CT’s acquired for HNC cases (nasopharynx, base of skull and paranasal sinus) using a research planning system (Monaco, v5.09.06, Elekta) employing Montemore » Carlo dose calculations with or without the presence of a transverse magnetic field (TMF). The dose in the air cavity was calculated in a 1 & 2 mm thick tissue layer, while the dose to the skin was calculated in a 1, 3 and 5 mm thick tissue layer. The maximum dose received in 1 cc volume, D1cc, were collected at different TMF strengths. Plan qualities generated with or without TMF or with increasing TMF were compared in terms of commonly-used dose-volume parameters (DVPs). Results: Variations in DVPs between plans with and without a TMF present were found to be within 5% of the planning CT. The presence of a TMF results in <5% changes in sinus air tissue interface. The largest skin dose differences with and without TMF were found within 1 mm of the skin surface Conclusion: The presence of a TMF results in practically insignificant changes in HNC IMRT plan quality, except for skin dose. Planning optimization with skin DV constraints could reduce the skin doses. This research was partially supported by Elekta Inc. (Crowley, U.K.)« less

Development of a silicon diode detector for skin dosimetry in radiotherapy.

PubMed

Vicoroski, Nikolina; Espinoza, Anthony; Duncan, Mitchell; Oborn, Bradley M; Carolan, Martin; Metcalfe, Peter; Menichelli, David; Perevertaylo, Vladimir L; Lerch, Michael L F; Rosenfeld, Anatoly B; Petasecca, Marco

2017-10-01

The aim of in vivo skin dosimetry was to measure the absorbed dose to the skin during radiotherapy, when treatment planning calculations cannot be relied on. It is of particularly importance in hypo-fractionated stereotactic modalities, where excessive dose can lead to severe skin toxicity. Currently, commercial diodes for such applications are with water equivalent depths ranging from 0.5 to 0.8 mm. In this study, we investigate a new detector for skin dosimetry based on a silicon epitaxial diode, referred to as the skin diode. The skin diode is manufactured on a thin epitaxial layer and packaged using the "drop-in" technology. It was characterized in terms of percentage depth dose, dose linearity, and dose rate dependence, and benchmarked against the Attix ionization chamber. The response of the skin diode in the build-up region of the percentage depth dose (PDD) curve of a 6 MV clinical photon beam was investigated. Geant4 radiation transport simulations were used to model the PDD in order to estimate the water equivalent measurement depth (WED) of the skin diode. Measured output factors using the skin diode were compared with the MOSkin detector and EBT3 film at 10 cm depth and at surface at isocenter of a water equivalent phantom. The intrinsic angular response of the skin diode was also quantified in charge particle equilibrium conditions (CPE) and at the surface of a solid water phantom. Finally, the radiation hardness of the skin diode up to an accumulated dose of 80 kGy using photons from a Co-60 gamma source was evaluated. The PDD curve measured with the skin diode was within 0.5% agreement of the equivalent Geant4 simulated curve. When placed at the phantom surface, the WED of the skin diode was estimated to be 0.075 ± 0.005 mm from Geant4 simulations and was confirmed using the response of a corrected Attix ionization chamber placed at water equivalent depth of 0.075 mm, with the measurement agreement to within 0.3%. The output factor measurements at 10 cm depth were within 2% of those measured with film and the MOSkin detector down to a field size of 2 × 2 cm 2 . The dose-response for all detector samples was linear and with a repeatability within 0.2%. The skin diode intrinsic angular response showed a maximum deviation of 8% at 90 degrees and from 0 to 60 degree is less than 5%. The radiation sensitivity reduced by 25% after an accumulated dose of 20 kGy but after was found to stabilize. At 60 kGy total accumulated dose the response was within 2% of that measured at 20 kGy total accumulated dose. This work characterizes an innovative detector for in vivo and real-time skin dose measurements that is based on an epitaxial silicon diode combined with the Centre for Medical Radiation Physics (CMRP) "drop-in" packaging technology. The skin diode proved to have a water equivalent depth of measurement of 0.075 ± 0.005 mm and the ability to measure doses accurately relative to reference detectors. © 2017 American Association of Physicists in Medicine.

External beam boost versus interstitial high-dose-rate brachytherapy boost in the adjuvant radiotherapy following breast-conserving therapy in early-stage breast cancer: a dosimetric comparison

PubMed Central

Melchert, Corinna; Kovács, György

2016-01-01

Purpose This study aims to compare the dosimetric data of local tumor's bed dose escalation (boost) with photon beams (external beam radiation therapy – EBRT) versus high-dose-rate interstitial brachytherapy (HDR-BT) after breast-conserving treatment in women with early-stage breast cancer. Material and methods We analyzed the treatment planning data of 136 irradiated patients, treated between 2006 and 2013, who underwent breast-conserving surgery and adjuvant whole breast irradiation (WBI; 50.4 Gy) and boost (HDR-BT: 10 Gy in one fraction [n = 36]; EBRT: 10 Gy in five fractions [n = 100]). Organs at risk (OAR; heart, ipsilateral lung, skin, most exposed rib segment) were delineated. Dosimetric parameters were calculated with the aid of dose-volume histograms (DVH). A non-parametric test was performed to compare the two different boost forms. Results There was no difference for left-sided cancers regarding the maximum dose to the heart (HDR-BT 29.8% vs. EBRT 29.95%, p = 0.34). The maximum doses to the other OAR were significantly lower for HDR-BT (Dmax lung 47.12% vs. 87.7%, p < 0.01; rib 61.17% vs. 98.5%, p < 0.01; skin 57.1% vs. 94.75%, p < 0.01; in the case of right-sided breast irradiation, dose of the heart 6.00% vs. 16.75%, p < 0.01). Conclusions Compared to EBRT, local dose escalation with HDR-BT presented a significant dose reduction to the investigated OAR. Only left-sided irradiation showed no difference regarding the maximum dose to the heart. Reducing irradiation exposure to OAR could result in a reduction of long-term side effects. Therefore, from a dosimetric point of view, an interstitial boost complementary to WBI via EBRT seems to be more advantageous in the adjuvant radiotherapy of breast cancer. PMID:27648082

Significance of including field non-uniformities such as the heel effect and beam scatter in the determination of the skin dose distribution during interventional fluoroscopic procedures

NASA Astrophysics Data System (ADS)

Rana, Vijay; Gill, Kamaljit; Rudin, Stephen; Bednarek, Daniel R.

2012-03-01

The current version of the real-time skin-dose-tracking system (DTS) we have developed assumes the exposure is contained within the collimated beam and is uniform except for inverse-square variation. This study investigates the significance of factors that contribute to beam non-uniformity such as the heel effect and backscatter from the patient to areas of the skin inside and outside the collimated beam. Dose-calibrated Gafchromic film (XR-RV3, ISP) was placed in the beam in the plane of the patient table at a position 15 cm tube-side of isocenter on a Toshiba Infinix C-Arm system. Separate exposures were made with the film in contact with a block of 20-cm solid water providing backscatter and with the film suspended in air without backscatter, both with and without the table in the beam. The film was scanned to obtain dose profiles and comparison of the profiles for the various conditions allowed a determination of field non-uniformity and backscatter contribution. With the solid-water phantom and with the collimator opened completely for the 20-cm mode, the dose profile decreased by about 40% on the anode side of the field. Backscatter falloff at the beam edge was about 10% from the center and extra-beam backscatter decreased slowly with distance from the field, being about 3% of the beam maximum at 6 cm from the edge. Determination of the magnitude of these factors will allow them to be included in the skin-dose-distribution calculation and should provide a more accurate determination of peak-skin dose for the DTS.

Absorption of ethanol, acetone, benzene and 1,2-dichloroethane through human skin in vitro: a test of diffusion model predictions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gajjar, Rachna M.; Kasting, Gerald B., E-mail: Gerald.Kasting@uc.edu

The overall goal of this research was to further develop and improve an existing skin diffusion model by experimentally confirming the predicted absorption rates of topically-applied volatile organic compounds (VOCs) based on their physicochemical properties, the skin surface temperature, and the wind velocity. In vitro human skin permeation of two hydrophilic solvents (acetone and ethanol) and two lipophilic solvents (benzene and 1,2-dichloroethane) was studied in Franz cells placed in a fume hood. Four doses of each {sup 14}C-radiolabed compound were tested — 5, 10, 20, and 40 μL cm{sup −2}, corresponding to specific doses ranging in mass from 5.0 tomore » 63 mg cm{sup −2}. The maximum percentage of radiolabel absorbed into the receptor solutions for all test conditions was 0.3%. Although the absolute absorption of each solvent increased with dose, percentage absorption decreased. This decrease was consistent with the concept of a stratum corneum deposition region, which traps small amounts of solvent in the upper skin layers, decreasing the evaporation rate. The diffusion model satisfactorily described the cumulative absorption of ethanol; however, values for the other VOCs were underpredicted in a manner related to their ability to disrupt or solubilize skin lipids. In order to more closely describe the permeation data, significant increases in the stratum corneum/water partition coefficients, K{sub sc}, and modest changes to the diffusion coefficients, D{sub sc}, were required. The analysis provided strong evidence for both skin swelling and barrier disruption by VOCs, even by the minute amounts absorbed under these in vitro test conditions. - Highlights: • Human skin absorption of small doses of VOCs was measured in vitro in a fume hood. • The VOCs tested were ethanol, acetone, benzene and 1,2-dichloroethane. • Fraction of dose absorbed for all compounds at all doses tested was less than 0.3%. • The more aggressive VOCs absorbed at higher levels than diffusion model predictions. • We conclude that even small exposures to VOCs temporarily alter skin permeability.« less

Estimation of the radiation dose from radiotherapy for skin haemangiomas in childhood: the ICTA software for epidemiology

NASA Astrophysics Data System (ADS)

Shamsaldin, A.; Lundell, M.; Diallo, I.; Ligot, L.; Chavaudra, J.; de Vathaire, F.

2000-12-01

Radium applicators and pure beta emitters have been widely used in the past to treat skin haemangioma in early childhood. A well defined relationship between the low doses received from these applicators and radiation-induced cancers requires accurate dosimetry. A human-based CT scan phantom has been used to simulate every patient and treatment condition and then to calculate the source-target distance when radium and pure beta applicators were used. The effective transmission factor ϕ(r) for the gamma spectrum emitted by the radium sources applied on the skin surface was modelled using Monte Carlo simulations. The well-known quantization approach was used to calculate gamma doses delivered from radium applicators to various anatomical points. For 32P, 90Sr/90Y applicators and 90Y needles we have used the apparent exponential attenuation equation. The dose calculation algorithm was integrated into the ICTA software (standing for a model that constructs an Individualized phantom based on CT slices and Auxological data), which has been developed for epidemiological studies of cohorts of patients who received radium and beta-treatments for skin haemangioma. The ϕ(r) values obtained for radium skin applicators are in good agreement with the available values in the first 10 cm but higher at greater distances. Gamma doses can be calculated with this algorithm at 165 anatomical points throughout the body of patients treated with radium applicators. Lung heterogeneity and air crossed by the gamma rays are considered. Comparison of absorbed doses in water from a 10 mg equivalent radium source simulated by ICTA with those measured at the Radiumhemmet, Karolinska Hospital (RAH) showed good agreement, but ICTA estimation of organ doses did not always correspond those estimated at the RAH. Beta doses from 32P, 90Sr/90Y applicators and 90Y needles are calculated up to the maximum beta range (11 mm).

SU-F-P-58: Squamous Cell and Basal Cell Carcinoma of the Skin Treated with a Freiburg Flap Applicator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dou, K; Li, B; Jacobs, M

Purpose: To treat squamous cell and basal cell carcinoma of the skin with the Freiburg flap applicator using a high dose rate modality of an Elekta Flexitron or MicroSelectron for radiation delivery by compensating the dose deviation resulting from the incomplete scatter environment. Methods: Patients were selected to have lesions greater than or equal to 2cm. A mask might be needed depending on special locations. The lesions on the eyelid and face presented in this research were, however, treated without a mask. Cutting the flap into a shape conformal to the target and attaching it to the mask were usedmore » in order to make the treatment reproducible. Patients were scanned with a Philips Big Bore Brilliant CT. A 1cm margin was added to the lesion. An Elekta Oncentra Brachy treatment planning system ver. 4.3 was used for treatment planning. 40 Gy in 10 or 8 fractions was prescribed to the 1cm depth. The Freiburg flap was aligned and verified by CT scanning prior to treatment. Results: Three patients with squamous cell and basal cell carcinoma of the skin were treated with the Freiburg flap applicator. Lesion sizes ranged from 2cm to 6 cm in a maximum dimension. With treatment planning, we made a dose correction for compensating the dose deviation resulting from the incomplete scatter environment of the flap applicators exposed to air. The flap was also covered by a 4cm bolus in order to obtain more back scattered radiation during treatment. Six month follow up showed a very good cosmetic result. Conclusion: The Freiburg flap brachytherapy offers a non-invasive skin cancer treatment with a high skin dose delivered to the tumor while a low dose sparing the surrounding health tissue. It is a promising alternative to skin cancer surgery or external beam radiation therapy.« less

Residue depletion of thiamphenicol in the sea-bass.

PubMed

Intorre, L; Castells, G; Cristòfol, C; Bertini, S; Soldani, G; Arboix, M

2002-02-01

The residue depletion of thiamphenicol (TAP) was investigated in the sea-bass (Dicentrarchus labrax) after 5 days' treatment with medicated food at a dose of 15 or 30 mg/kg bw/day. Fish were sampled for blood and muscle + skin from 3 h until 14 days after treatment. Thiamphenicol concentrations were assayed by high performance liquid chromatography. Thiamphenicol concentrations measured 3 h after stopping treatment were 0.77 microg/mL and 0.91 (15 mg/kg dose) or 1.32 microg/mL and 1.47 microg/g (30 mg/kg dose), in plasma and muscle + skin, respectively. After a withdrawal of 3 days, plasma and tissue concentrations were: 0.08 microg/mL and 0.03 microg/g (lower dose) or 0.12 microg/mL and 0.06 microg/g (higher dose), respectively. Thiamphenicol was not detectable either in plasma or in tissues on days 7, 10 and 14 following withdrawal of the medicated food. Based on maximum residue levels (MRL) for TAP in fin fish, established at 50 microg/kg for muscle and skin in natural proportions, a withdrawal period of 5 and 6 days is proposed, after treatment at 15 or 30 mg/kg of TAP with medicated feed pellets, respectively, to avoid the presence of violative residues in the edible tissues of the sea-bass.

Thermal Skin Damage During Reirradiation and Hyperthermia Is Time-Temperature Dependent

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakker, Akke, E-mail: akke.bakker@amc.uva.nl; Kolff, M. Willemijn; Holman, Rebecca

Purpose: To investigate the relationship of thermal skin damage (TSD) to time–temperature isoeffect levels for patients with breast cancer recurrence treated with reirradiation plus hyperthermia (reRT + HT), and to investigate whether the treatment history of previous treatments (scar tissue) is a risk factor for TSD. Methods and Materials: In this observational study, temperature characteristics of hyperthermia sessions were analyzed in 262 patients with recurrent breast cancer treated in the AMC between 2010 and 2014 with reirradiation and weekly hyperthermia for 1 hour. Skin temperature was measured using a median of 42 (range, 29-82) measurement points per hyperthermia session. Results: Sixty-eight patients (26%) developed 79more » sites of TSD, after the first (n=26), second (n=17), third (n=27), and fourth (n=9) hyperthermia session. Seventy percent of TSD occurred on or near scar tissue. Scar tissue reached higher temperatures than other skin tissue (0.4°C, P<.001). A total of 102 measurement points corresponded to actual TSD sites in 35 of 79 sessions in which TSD developed. Thermal skin damage sites had much higher maximum temperatures than non-TSD sites (2.8°C, P<.001). Generalized linear mixed models showed that the probability of TSD is related to temperature and thermal dose values (P<.001) and that scar tissue is more at risk (odds ratio 0.4, P<.001). Limiting the maximum temperature of a measurement point to 43.7°C would mean that the probability of observing TSD was at most 5%. Conclusion: Thermal skin damage during reRT + HT for recurrent breast cancer was related to higher local temperatures and time–temperature isoeffect levels. Scar tissue reached higher temperatures than other skin tissue, and TSD occurred at lower temperatures and thermal dose values in scar tissue compared with other skin tissue. Indeed, TSD developed often on and around scar tissue from previous surgical procedures.« less

Experimental assessment of the Advanced Collapsed-cone Engine for scalp brachytherapy treatments.

PubMed

Cawston-Grant, Brie; Morrison, Hali; Sloboda, Ron S; Menon, Geetha

To experimentally assess the performance of the Advanced Collapsed-cone Engine (ACE) for 192 Ir high-dose-rate brachytherapy treatment planning of nonmelanoma skin cancers of the scalp. A layered slab phantom was designed to model the head (skin, skull, and brain) and surface treatment mold using tissue equivalent materials. Six variations of the phantom were created by varying skin thickness, skull thickness, and size of air gap between the mold and skin. Treatment planning was initially performed using the Task Group 43 (TG-43) formalism with CT images of each phantom variation. Doses were recalculated using standard and high accuracy modes of ACE. The plans were delivered to Gafchromic EBT3 film placed between different layers of the phantom. Doses calculated by TG-43 and ACE and those measured by film agreed with each other at most locations within the phantoms. For a given phantom variation, average TG-43- and ACE-calculated doses were similar, with a maximum difference of (3 ± 12)% (k = 2). Compared to the film measurements, TG-43 and ACE overestimated the film-measured dose by (13 ± 12)% (k = 2) for one phantom variation below the skull layer. TG-43- and ACE-calculated and film-measured doses were found to agree above the skull layer of the phantom, which is where the tumor would be located in a clinical case. ACE appears to underestimate the attenuation through bone relative to that measured by film; however, the dose to bone is below tolerance levels for this treatment. Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Clinical implementation of MOSFET detectors for dosimetry in electron beams.

PubMed

Bloemen-van Gurp, Esther J; Minken, Andre W H; Mijnheer, Ben J; Dehing-Oberye, Cary J G; Lambin, Philippe

2006-09-01

To determine the factors converting the reading of a MOSFET detector placed on the patient's skin without additional build-up to the dose at the depth of dose maximum (D(max)) and investigate their feasibility for in vivo dose measurements in electron beams. Factors were determined to relate the reading of a MOSFET detector to D(max) for 4 - 15 MeV electron beams in reference conditions. The influence of variation in field size, SSD, angle and field shape on the MOSFET reading, obtained without additional build-up, was evaluated using 4, 8 and 15 MeV beams and compared to ionisation chamber data at the depth of dose maximum (z(max)). Patient entrance in vivo measurements included 40 patients, mostly treated for breast tumours. The MOSFET reading, converted to D(max), was compared to the dose prescribed at this depth. The factors to convert MOSFET reading to D(max) vary between 1.33 and 1.20 for the 4 and 15 MeV beams, respectively. The SSD correction factor is approximately 8% for a change in SSD from 95 to 100 cm, and 2% for each 5-cm increment above 100 cm SSD. A correction for fields having sides smaller than 6 cm and for irregular field shape is also recommended. For fields up to 20 x 20 cm(2) and for oblique incidence up to 45 degrees, a correction is not necessary. Patient measurements demonstrated deviations from the prescribed dose with a mean difference of -0.7% and a standard deviation of 2.9%. Performing dose measurements with MOSFET detectors placed on the patient's skin without additional build-up is a well suited technique for routine dose verification in electron beams, when applying the appropriate conversion and correction factors.

Mars surface radiation exposure for solar maximum conditions and 1989 solar proton events

NASA Technical Reports Server (NTRS)

Simonsen, Lisa C.; Nealy, John E.

1992-01-01

The Langley heavy-ion/nucleon transport code, HZETRN, and the high-energy nucleon transport code, BRYNTRN, are used to predict the propagation of galactic cosmic rays (GCR's) and solar flare protons through the carbon dioxide atmosphere of Mars. Particle fluences and the resulting doses are estimated on the surface of Mars for GCR's during solar maximum conditions and the Aug., Sep., and Oct. 1989 solar proton events. These results extend previously calculated surface estimates for GCR's at solar minimum conditions and the Feb. 1956, Nov. 1960, and Aug. 1972 solar proton events. Surface doses are estimated with both a low-density and a high-density carbon dioxide model of the atmosphere for altitudes of 0, 4, 8, and 12 km above the surface. A solar modulation function is incorporated to estimate the GCR dose variation between solar minimum and maximum conditions over the 11-year solar cycle. By using current Mars mission scenarios, doses to the skin, eye, and blood-forming organs are predicted for short- and long-duration stay times on the Martian surface throughout the solar cycle.

Absorption of ethanol, acetone, benzene and 1,2-dichloroethane through human skin in vitro: a test of diffusion model predictions.

PubMed

Gajjar, Rachna M; Kasting, Gerald B

2014-11-15

The overall goal of this research was to further develop and improve an existing skin diffusion model by experimentally confirming the predicted absorption rates of topically-applied volatile organic compounds (VOCs) based on their physicochemical properties, the skin surface temperature, and the wind velocity. In vitro human skin permeation of two hydrophilic solvents (acetone and ethanol) and two lipophilic solvents (benzene and 1,2-dichloroethane) was studied in Franz cells placed in a fume hood. Four doses of each (14)C-radiolabed compound were tested - 5, 10, 20, and 40μLcm(-2), corresponding to specific doses ranging in mass from 5.0 to 63mgcm(-2). The maximum percentage of radiolabel absorbed into the receptor solutions for all test conditions was 0.3%. Although the absolute absorption of each solvent increased with dose, percentage absorption decreased. This decrease was consistent with the concept of a stratum corneum deposition region, which traps small amounts of solvent in the upper skin layers, decreasing the evaporation rate. The diffusion model satisfactorily described the cumulative absorption of ethanol; however, values for the other VOCs were underpredicted in a manner related to their ability to disrupt or solubilize skin lipids. In order to more closely describe the permeation data, significant increases in the stratum corneum/water partition coefficients, Ksc, and modest changes to the diffusion coefficients, Dsc, were required. The analysis provided strong evidence for both skin swelling and barrier disruption by VOCs, even by the minute amounts absorbed under these in vitro test conditions. Copyright © 2014 Elsevier Inc. All rights reserved.

Acemannan-containing wound dressing gel reduces radiation-induced skin reactions in C3H mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roberts, D.B.; Travis, E.L.

To determine (a) whether a wound dressing gel that contains acemannan extracted from aloe leaves affects the severity of radiation-induced acute skin reactions in C3H mice; (b) if so, whether other commercially available gels such as a personal lubricating jelly and a healing ointment have similar effects; and (c) when the wound dressing gel should be applied for maximum effect. Male C3H mice received graded single doses of gamma radiation ranging from 30 to 47.5 Gy to the right leg. In most experiments, the gel was applied daily beginning immediately after irradiation. Dose-response curves were obtained by plotting the percentagemore » of mice that reached or exceeded a given peak skin reaction as a function of dose. Curves were fitted by logit analysis and ED{sub 50} values, and 95% confidence limits were obtained. The average peak skin reactions of the wound dressing gel-treated mice were lower than those of the untreated mice at all radiation doses tested. The ED{sub 50} values for skin reactions of 2.0-2.75 were approximately 7 Gy higher in the wound dressing gel-treated mice. The average peak skin reactions and the ED{sub 50} values for mice treated with personal lubricating jelly or healing ointment were similar to irradiated control values. Reduction in the percentage of mice with skin reactions of 2.5 or more was greatest in the groups that received wound dressing gel for at least 2 weeks beginning immediately after irradiation. There was no effect if gel was applied only before irradiation or beginning 1 week after irradiation. Wound dressing gel, but not personal lubricating jelly or healing ointment, reduces acute radiation-induced skin reactions in C3H mice if applied daily for at least 2 weeks beginning immediately after irradiation. 31 refs., 4 figs., 1 tab.« less

Radiation dose enhancement in skin therapy with nanoparticle addition: A Monte Carlo study on kilovoltage photon and megavoltage electron beams

PubMed Central

Zheng, Xiao J; Chow, James C L

2017-01-01

AIM To investigated the dose enhancement due to the incorporation of nanoparticles in skin therapy using the kilovoltage (kV) photon and megavoltage (MV) electron beams. Monte Carlo simulations were used to predict the dose enhancement when different types and concentrations of nanoparticles were added to skin target layers of varying thickness. METHODS Clinical kV photon beams (105 and 220 kVp) and MV electron beams (4 and 6 MeV), produced by a Gulmay D3225 orthovoltage unit and a Varian 21 EX linear accelerator, were simulated using the EGSnrc Monte Carlo code. Doses at skin target layers with thicknesses ranging from 0.5 to 5 mm for the photon beams and 0.5 to 10 mm for the electron beams were determined. The skin target layer was added with the Au, Pt, I, Ag and Fe2O3 nanoparticles with concentrations ranging from 3 to 40 mg/mL. The dose enhancement ratio (DER), defined as the dose at the target layer with nanoparticle addition divided by the dose at the layer without nanoparticle addition, was calculated for each nanoparticle type, nanoparticle concentration and target layer thickness. RESULTS It was found that among all nanoparticles, Au had the highest DER (5.2-6.3) when irradiated with kV photon beams. Dependence of the DER on the target layer thickness was not significant for the 220 kVp photon beam but it was for 105 kVp beam for Au nanoparticle concentrations higher than 18 mg/mL. For other nanoparticles, the DER was dependent on the atomic number of the nanoparticle and energy spectrum of the photon beams. All nanoparticles showed an increase of DER with nanoparticle concentration during the photon beam irradiations regardless of thickness. For electron beams, the Au nanoparticles were found to have the highest DER (1.01-1.08) when the beam energy was equal to 4 MeV, but this was drastically lower than the DER values found using photon beams. The DER was also found affected by the depth of maximum dose of the electron beam and target thickness. For other nanoparticles with lower atomic number, DERs in the range of 0.99-1.02 were found using the 4 and 6 MeV electron beams. CONCLUSION In nanoparticle-enhanced skin therapy, Au nanoparticle addition can achieve the highest dose enhancement with 105 kVp photon beams. Electron beams, while popular for skin therapy, did not produce as high dose enhancements as kV photon beams. Additionally, the DER is dependent on nanoparticle type, nanoparticle concentration, skin target thickness and energies of the photon and electron beams. PMID:28298966

Comparison of measured and estimated maximum skin doses during CT fluoroscopy lung biopsies.

PubMed

Zanca, F; Jacobs, A; Crijns, W; De Wever, W

2014-07-01

To measure patient-specific maximum skin dose (MSD) associated with CT fluoroscopy (CTF) lung biopsies and to compare measured MSD with the MSD estimated from phantom measurements, as well as with the CTDIvol of patient examinations. Data from 50 patients with lung lesions who underwent a CT fluoroscopy-guided biopsy were collected. The CT protocol consisted of a low-kilovoltage (80 kV) protocol used in combination with an algorithm for dose reduction to the radiology staff during the interventional procedure, HandCare (HC). MSD was assessed during each intervention using EBT2 gafchromic films positioned on patient skin. Lesion size, position, total fluoroscopy time, and patient-effective diameter were registered for each patient. Dose rates were also estimated at the surface of a normal-size anthropomorphic thorax phantom using a 10 cm pencil ionization chamber placed at every 30°, for a full rotation, with and without HC. Measured MSD was compared with MSD values estimated from the phantom measurements and with the cumulative CTDIvol of the procedure. The median measured MSD was 141 mGy (range 38-410 mGy) while the median cumulative CTDIvol was 72 mGy (range 24-262 mGy). The ratio between the MSD estimated from phantom measurements and the measured MSD was 0.87 (range 0.12-4.1) on average. In 72% of cases the estimated MSD underestimated the measured MSD, while in 28% of the cases it overestimated it. The same trend was observed for the ratio of cumulative CTDIvol and measured MSD. No trend was observed as a function of patient size. On average, estimated MSD from dose rate measurements on phantom as well as from CTDIvol of patient examinations underestimates the measured value of MSD. This can be attributed to deviations of the patient's body habitus from the standard phantom size and to patient positioning in the gantry during the procedure.

Estimation of human percutaneous bioavailability for two novel brominated flame retardants, 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (EH-TBB) and bis(2-ethylhexyl) tetrabromophthalate (BEH-TEBP)

PubMed Central

Knudsen, Gabriel A.; Hughes, Michael F.; Sanders, J. Michael; Hall, Samantha M.; Birnbaum, Linda S.

2016-01-01

2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB) and bis(2-ethylhexyl)tetrabromophthalate (BEH-TEBP) are novel brominated flame retardants used in consumer products. A parallelogram approach was used to predict human dermal absorption and flux for EH-TBB and BEH-TEBP. [14C]-EH-TBB or [14C]-BEH-TEBP was applied to human or rat skin at 100 nmol/cm2 using a flow-through system. Intact rats received analogous dermal doses. Treated skin was washed and tape-stripped to remove “unabsorbed” [14C]-radioactivity after continuous exposure (24h). “Absorbed” was quantified using dermally retained [14C]-radioactivity; “penetrated” was calculated based on [14C]-radioactivity in media (in vitro) or excreta+tissues (in vivo). Human skin absorbed EH-TBB (24±1%) while 0.2±0.1% penetrated skin. Rat skin absorbed more (51±10%) and was more permeable (2±0.5%) to EH-TBB in vitro; maximal EH-TBB flux was 11±7 and 102±24 pmol-eq/cm2/h for human and rat skin, respectively. In vivo, 27±5% was absorbed and 13% reached systemic circulation after 24 h (maximum flux was 464±65 pmol-eq/cm2/h). BEH-TEBP in vitro penetrance was minimal (<0.01%) for rat or human skin. BEH-TEBP absorption was 12±11% for human skin and 41±3% for rat skin. In vivo, total absorption was 27±9%; 1.2% reached systemic circulation. In vitro maximal BEH-TEBP flux was 0.3±0.2 and 1±0.3 pmol-eq/cm2/h for human and rat skin; in vivo maximum flux for rat skin was 16±7 pmol-eq/cm2/h. EH-TBB was metabolized in rat and human skin to tetrabromobenzoic acid. BEH-TEBP-derived [14C]-radioactivity in the perfusion media could not be characterized. Less than 1% of the dose of EH-TBB and BEH-TEHP is estimated to reach the systemic circulation following human dermal exposure under the conditions tested. PMID:27732871

An Assessment of Common Approaches to Estimating Peak Skin Dose Resulting From Fluoroscopically Guided Interventions

NASA Astrophysics Data System (ADS)

Smith, Caleb Martin

Fluoroscopy guided procedures are increasing in complexity, and with that, Peak Skin Doses (PSD) that produce cutaneous radiation injury are a growing concern. Direct measurement of PSD is possible, but the decision to do so must be made in advance. PSD estimates and correctly monitoring their possible deterministic skin injuries are important to patient care. Three methods of indirect PSD estimation are examined for nine cases at MedStar Georgetown University Hospital. The aim of the study is to determine the magnitude of variation between these three methods for estimating the PSD. Method 1 (Fluoroscopy Time and Maximum Entrance Skin Exposure) was used at MedStar Georgetown University Hospital up until 2016. Methods 2 and 3 incorporate procedure information (Reference Point Air Kerma, Source-to-Patent distance, and Backscatter Factor) from DICOM (Digital Imaging and Communications in Medicine) tags into PSD estimates. Method 1 PSD estimates are vastly different, by as much as 136%, than those from Methods 2 and 3. Method 2 and 3 PSD estimates differ very little, 7.3% or less. Governing bodies have discounted Method 1 as a reliable dose metric because of its poor correlation with PSD. The accuracy of Method 2 is suitable to determine PSD and which dose band a patient fits so their injuries can be accurately monitored. Method 3, the most time intensive approach, should only be used in the case of a sentinel event where a full investigation is warranted.

Chemical modification of normal tissue damage induced by photodynamic therapy.

PubMed Central

Sigdestad, C. P.; Fingar, V. H.; Wieman, T. J.; Lindberg, R. D.

1996-01-01

One of the limitations of successful use of photodynamic therapy (PDT) employing porphyrins is the acute and long-term cutaneous photosensitivity. This paper describes results of experiments designed to test the effects of two radiation protective agents (WR-2721, 500 mg kg-1 or WR-3689, 700 mg kg-1) on murine skin damage induced by PDT. C3H mice were shaved and depilated three days prior to injection with the photosensitiser, Photofrin (5 or 10 mg kg-1). Twenty-four hours later, the mice were injected intraperitoneally with a protector 30 min prior to Argon dye laser (630 nm) exposure. The skin response was followed for two weeks post irradiation using an arbitrary response scale. A light dose response as well as a drug dose response was obtained. The results indicate that both protectors reduced the skin response to PDT, however WR-2721 was demonstrated to be the most effective. The effect of the protectors on vascular stasis after PDT was determined using a fluorescein dye exclusion assay. In mice treated with Photofrin (5 mg kg-1), and 630 nm light (180 J cm-2) pretreatment with either WR-2721 or WR-3689 resulted in significant protection of the vascular effects of PDT. These studies document the ability of the phosphorothioate class of radiation protective agents to reduce the effects of light on photosensitized skin. They do so in a drug dose-dependent fashion with maximum protection at the highest drug doses. PMID:8763855

Ultrasound therapy applicators for controlled thermal modification of tissue

NASA Astrophysics Data System (ADS)

Burdette, E. Clif; Lichtenstiger, Carol; Rund, Laurie; Keralapura, Mallika; Gossett, Chad; Stahlhut, Randy; Neubauer, Paul; Komadina, Bruce; Williams, Emery; Alix, Chris; Jensen, Tor; Schook, Lawrence; Diederich, Chris J.

2011-03-01

Heat therapy has long been used for treatments in dermatology and sports medicine. The use of laser, RF, microwave, and more recently, ultrasound treatment, for psoriasis, collagen reformation, and skin tightening has gained considerable interest over the past several years. Numerous studies and commercial devices have demonstrated the efficacy of these methods for treatment of skin disorders. Despite these promising results, current systems remain highly dependent on operator skill, and cannot effectively treat effectively because there is little or no control of the size, shape, and depth of the target zone. These limitations make it extremely difficult to obtain consistent treatment results. The purpose of this study was to determine the feasibility for using acoustic energy for controlled dose delivery sufficient to produce collagen modification for the treatment of skin tissue in the dermal and sub-dermal layers. We designed and evaluated a curvilinear focused ultrasound device for treating skin disorders such as psoriasis, stimulation of wound healing, tightening of skin through shrinkage of existing collagen and stimulation of new collagen formation, and skin cancer. Design parameters were examined using acoustic pattern simulations and thermal modeling. Acute studies were performed in 201 freshly-excised samples of young porcine underbelly skin tissue and 56 in-vivo treatment areas in 60- 80 kg pigs. These were treated with ultrasound (9-11MHz) focused in the deep dermis. Dose distribution was analyzed and gross pathology assessed. Tissue shrinkage was measured based on fiducial markers and video image registration and analyzed using NIH Image-J software. Comparisons were made between RF and focused ultrasound for five energy ranges. In each experimental series, therapeutic dose levels (60degC) were attained at 2-5mm depth. Localized collagen changes ranged from 1-3% for RF versus 8-15% for focused ultrasound. Therapeutic ultrasound applied at high frequencies can achieve temperatures and dose distributions which concentrate in a depth profile that coincides with the location of maximum structural collagen content in skin tissues. Using an appropriate transducer configuration produces coverage of significant lateral area, thus making this a practical approach for treatment of skin disorders.

Gamma-H2AX as a biomarker of DNA damage induced by ionizing radiation in targeted and bystander human artificial skin models and peripheral blood lymphocytes

NASA Astrophysics Data System (ADS)

Redon, Christophe; Dickey, Jennifer; Bonner, William; Sedelnikova, Olga

Ionizing radiation (IR) exposure is inevitable. In addition to exposure from cosmic rays, the sun and radioactive substances, modern society has created new sources of radiation exposure such as space and high altitude journeys, X-ray diagnostics, radiological treatments and the increasing threat of radiobiological terrorism. For these reasons, a reliable, reproducible and sensitive assessment of dose and time exposure to IR is essential. We developed a minimally invasive diagnostic test for IR exposure based on detection of a phosphorylated variant of histone H2AX (gamma-H2AX), which occurs specifically at sites of DNA double-strand breaks (DSBs). The phosphorylation of thousands of H2AX molecules forms a gamma-H2AX focus in the chromatin flanking the DSB site that can be detected in situ. We analyzed gamma- H2AX focus formation in both directly irradiated cells as well as in un-irradiated "bystanders" in close contact with irradiated cells. In order to insure minimal invasiveness, we examined commercially available artificial skin models as a surrogate for human skin biopsies as well as peripheral blood lymphocytes. In human skin models, cells in a thin plane were microbeamirradiated and gamma-H2AX formation was measured both in irradiated and in distal bystander cells over time. In irradiated cells DSB formation reached a maximum at 15-30 minutes post- IR and then declined within several hours; all cells were affected. In marked contrast, the incidence of DSBs in bystander cells reached a maximum by 12-48 hours post-irradiation, gradually decreasing over the 7 day time course. At the maxima, 40-60% of bystander cells were affected. Similarly, we analyzed blood samples exposed to IR ex vivo at doses ranging from 0.02 to 3 Gy. The amount of DNA damage was linear in respect to radiation dose and independent of the age or sex of the blood donor. The method is highly reproducible and highly sensitive. In directly irradiated cells, the number of gamma-H2AX foci peaked 30 min after irradiation and then declined at a relatively steady pace as the cell repaired the DNA damage. Radiation effects were still detectable after 48 hrs for doses greater than 1 Gy and remained linear to initial dose. Activated bystander lymphocytes cultured with media from irradiated lymphocytes exhibited a two-fold increased damage response as seen by gamma- H2AX formation. The effect reached a maximum 3 hrs post-exposure and was retained for over 24 hrs. Thus, detection of gamma-H2AX formation to determine DNA damage in a minimally invasive skin test and a non-invasive blood test could be useful and promising tools to analyze direct and indirect effects of radiation exposure.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batal, Mohamed; Département de Toxicologie et Risques Chimiques, Unité de Brûlure Chimique, Institut de Recherche Biomédicale des Armées, Antenne de La Tronche; Boudry, Isabelle

Sulfur mustard (SM) is a chemical warfare agent that targets skin where it induces large blisters. DNA alkylation is a critical step to explain SM-induced cutaneous symptoms. We determined the kinetics of formation of main SM–DNA adducts and compare it with the development of the SM-induced pathogenesis in skin. SKH-1 mice were exposed to 2, 6 and 60 mg/kg of SM and treated skin was biopsied between 6 h and 21 days. Formation of SM DNA adducts was dose-dependent with a maximum immediately after exposure. However, adducts were persistent and still detectable 21 days post-exposure. The time-dependent formation of DNAmore » adducts was also found to be correlated with the appearance of apoptotic cells. This temporal correlation suggests that these two early events are responsible for the severity of the damage to the skin. Besides, SM–DNA adducts were also detected in areas located next to contaminated zone, thus suggesting that SM diffuses in skin. Altogether, this work provides for the first time a clear picture of SM-induced genotoxicity using DNA adducts as a marker. - Highlights: • Sulfur mustard adducts are formed in DNA after skin exposure. • DNA damage formation is an early event in the pathological process of skin burn. • The amount of SM–DNA adducts is maximal at the earliest time point investigated. • Adducts are still detected 3 weeks after exposure. • Sulfur mustard diffuses in skin especially when large doses are applied.« less

In vitro human skin penetration of geraniol and citronellol.

PubMed

Gilpin, Sarah; Hui, Xiaoying; Maibach, Howard

2010-01-01

Geraniol and citronellol are commonly used fragrance components in consumer products. Both are listed as alleged fragrance allergens that should be declared in the European Union when used in cosmetics and consumer products. Such allergenic potential is determined largely by effects on the skin once these materials penetrate and elicit an immune response. Few data demonstrate their penetration abilities or their effects on percutaneous absorption. We wanted to determine the effects of these materials on skin absorption. Skin penetration characterization via flow-through diffusion study serves as a reasonable model for determining dermal dosing for fragrance materials. Such characterization can be used for more accurate safety exposure calculations and regulatory determinations. Extensive comparisons to in vivo data in humans or closely related animals will be required before accepting flow-through diffusion methods as in vivo alternatives by industry and regulatory bodies. To evaluate the penetration abilities of geraniol and citronellol when they are used in a typical vehicle in consumer products. In vitro skin penetration of radiolabeled geraniol and citronellol was studied under occlusion in human cadaver skin, using flow-through diffusion cells for scintillation counting to determine the percentage of dose absorbed. For comparison, two doses of each material were used: 2% and 5% in 3:1 diethyl phthalate/ethanol. After 24 hours, geraniol and citronellol had relatively low skin absorption rates; 3.8% +/- 2.1% of 2% citronellol, 4.7% +/- 1.9% of 5% citronellol, 3.5% +/- 1.9% of 2% geraniol, and 7.3% +/- 1.1% of 5% geraniol were recovered from skin and receptor fluid compartments. These materials showed good mass-balance recovery. The majority of the dose was recovered in the skin washes (a minimum of 64.7% +/- 4.6% recovered for 2% citronellol and a maximum of 79.3% +/- 3.9% recovered for 5% geraniol). Receptor fluid collection points over time showed a linear increase in the amounts of citronellol and geraniol that penetrated the skin, although overall absorption values were quite small. In vitro results indicate that geraniol and citronellol have low potentials for skin penetration, which has implications for their ability to induce allergenicity and for more predictive toxicologic profiling of these materials. In vivo studies should be done to correlate the in vitro results.

Estimation of dose rates at the entrance surface for exposure scenarios of total body irradiation using MCNPX code

NASA Astrophysics Data System (ADS)

Cunha, J. S.; Cavalcante, F. R.; Souza, S. O.; Souza, D. N.; Santos, W. S.; Carvalho Júnior, A. B.

2017-11-01

One of the main criteria that must be held in Total Body Irradiation (TBI) is the uniformity of dose in the body. In TBI procedures the certification that the prescribed doses are absorbed in organs is made with dosimeters positioned on the patient skin. In this work, we modelled TBI scenarios in the MCNPX code to estimate the entrance dose rate in the skin for comparison and validation of simulations with experimental measurements from literature. Dose rates were estimated simulating an ionization chamber laterally positioned on thorax, abdomen, leg and thigh. Four exposure scenarios were simulated: ionization chamber (S1), TBI room (S2), and patient represented by hybrid phantom (S3) and water stylized phantom (S4) in sitting posture. The posture of the patient in experimental work was better represented by S4 compared with hybrid phantom, and this led to minimum and maximum percentage differences of 1.31% and 6.25% to experimental measurements for thorax and thigh regions, respectively. As for all simulations reported here the percentage differences in the estimated dose rates were less than 10%, we considered that the obtained results are consistent with experimental measurements and the modelled scenarios are suitable to estimate the absorbed dose in organs during TBI procedure.

SU-F-T-314: Estimation of Dose Distributions with Different Types of Breast Implants in Various Radiation Treatment Techniques for Breast Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, M; Lee, S; Suh, T

Purpose: This study investigates the effects of different kinds and designs of commercialized breast implants on the dose distributions in breast cancer radiotherapy under a variety of conditions. Methods: The dose for the clinical conventional tangential irradiation, Intensity Modulated Radiation Therapy (IMRT), volumetric modulated arc therapy (VMAT) breast plans was measured using radiochromic films and stimulated luminescence dosimeter (OSLD). The radiochromic film was used as an integrating dosimeter, while the OSLDs were used for real-time dosimetry to isolate the contribution of dose from individual segment. The films were placed at various slices in the Rando phantom and between the bodymore » and breast surface OSLDs were used to measure skin dose at 18 positions spaced on the two (right/left) breast. The implant breast was placed on the left side and the phantom breast was remained on the right side. Each treatment technique was performed on different size of the breasts and different shape of the breast implant. The PTV dose was prescribed 50.4 Gy and V47.88≥95%. Results: In different shapes of the breast implant, because of the shadow formed extensive around the breast implant, dose variation was relatively higher that of prescribed dose. As the PTV was delineated on the whole breast, maximum 5% dose error and average 3% difference was observed averagely. VMAT techniques largely decrease the contiguous hot spot in the skin by an average of 25% compared with IMRT. The both IMRT and VMAT techniques resulted in lower doses to normal critical structures than tangential plans for nearly all dose analyzation. Conclusion: Compared to the other technique, IMRT reduced radiation dose exposure to normal tissues and maintained reasonable target homogeneity and for the same target coverage, VMAT can reduce the skin dose in all the regions of the body.« less

[Prostate radiation therapy: in vivo measurement of the dose delivered by kV-CBCT].

PubMed

Marinello, G; Mege, J-P; Besse, M-C; Kerneur, G; Lagrange, J-L

2009-09-01

To investigate if the regular use of kV-CBCT notably increases the dose delivered to tumor and surrounding healthy tissues. Images were obtained using a Varian equipment (OBI version 1.3, 645 to 650 projections in 370 degrees to acquire image), and patients were irradiated at source-tumor distance: 100cm. In vivo measurements were performed using radio-thermoluminescent dosimeters Harshaw-TLD700H (TLD) at skin (anterior-posterior and lateral axis crossing the rotation axis), with a fourth TLD group under the table thanks to a retrolaser. TLD's were calibrated at the kV-CBCT effective energy (64 keV), and the method validated using an anthropomorphic phantom, in which Gafchromic EBT films were also inserted. The phantom study showed that the dose distribution depends on the phantom position relative to the axis and that the doses measured at the phantom surface using TLD and films (good agreement) were maximum at the entrance of the anterior-posterior axis. Their arithmetic mean was equal, or a slightly greater than doses measured at mid-thickness of the phantom and at the level of the rectum (OAR). In vivo measurements performed on the five first patients (125 kV-CBCT) yield a mean skin dose per kV-CBCT varying from 5.8+/-0.1 to 7.3+/-0.2 cGy on the anterior-posterior axis. Lateral skin doses vary from 3.4+/-0.2 to 4.5+/-0.2 cGy. Doses delivered by repeated kV-CBCT are not negligible. They should be taken into account, but questions about the RBE to be applied to kilovoltage X-rays are raised.

SU-F-T-01: Optimization of the Accelerated Partial Breast Brachytherapy Fractionation with Consideration of Physical Doses to Tumor and Organ at Risk

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, W; Huq, M

2016-06-15

Purpose: The accelerated partial breast irradiation (APBI) with brachytherapy prescribes 34Gy to be delivered in 10 fractions over 5 consecutive working days without considering the physical dose to the target and organs at risk (OARs) for an individual patient. The purpose of this study is to optimize the fractionation scheme by evaluating the radiation effect on tumor and OARs with a modified linear-quadratic (LQ) model based on dose-volume histograms (DVHs). Methods: Five breast patients treated with multilumen balloon brachytherapy were selected. The minimum skin and rib spacing were ranged from 2.5mm to 14.3mm and from 1.0mm to 25.0mm, respectively. Themore » LQ model parameters were set as: (1) breast: α=0.08, β=0.028, doubling time Tpot=14.4 days, and starting time Tk=21days; (2) skin: acute reaction α=0.101, β=0.009; late reaction α=0.064, β=0.029; (3) rib: α=0.3, β=0.12. Boundary dose Dt was 6 Gy for both target and OARs. The relation between radiation effects on the tumor (ET) and OARs (EOAR) were plotted for fraction number from 1 to 20. Results: The value of radiation effect from routine 3.4Gyx10 fractions was used as reference, ETref and EOARref. If set ET=ETref, the fractionation that results in minimum EOAR values correspond to the optimal fractionation. For these patients, the optimal numbers are 10 fractions for skin acute reaction, 18 fractions for skin and rib late reaction while the doses per fraction are 3.4Gy and 2.05–2.10Gy, respectively. If set EOAR=EOARref, the fractionation that results in a maximum ET value corresponds to the optimal fractionation. The optimal fractionation is 3.4Gyx10 fractions for skin acute reaction, and 2.10–2.25Gyx18 fractions for skin late reaction and rib. Conclusion: For APBI brachytherapy, the routine 3.4Gyx10 fractions is optimal fractionation for skin acute reaction, while 2.05–2.25Gyx18 fractions is optimal fractionation for late reaction of skin and rib.« less

Nitrogen and sulphur mustard induced histopathological observations in mouse visceral organs.

PubMed

Sharma, Manoj; Pant, S C; Pant, J C; Vijayaraghavan, R

2010-11-01

Nitrogen mustards (HN) and sulphur mustard (SM) are potent alkylating blister inducing chemical warfare agents. Single 1.0 LD50 dose produced a progressive fall in body weight from second day onwards in all groups of mustard agents exposed animals. Histological examination of spleen, liver skin and kidney revealed significant histopathological lesions in nitrogen mustards and sulphur mustard. These lesions include granulovascular degeneration with perinuclear clumping of the cytoplasm of hepatocytes and renal parenchymal cells. Renal lesions were characterized by congestion and hemorrhage. The maximum toxic manifestation were noted in spleen and skin of HN-3 exposed mice while sulphur mustard reported maximum toxicity in liver and kidneys. The study suggests both nitrogen mustards and sulphur mustard to be extremely toxic by percutaneous route based on histopathological observation and can contributed to earlier reported free radical generation by these toxicants.

A technique for pediatric total skin electron irradiation.

PubMed

Bao, Qinan; Hrycushko, Brian A; Dugas, Joseph P; Hager, Frederick H; Solberg, Timothy D

2012-03-20

Total skin electron irradiation (TSEI) is a special radiotherapy technique which has generally been used for treating adult patients with mycosis fungoides. Recently, two infants presented with leukemia cutis isolated to the skin requiring TSEI. This work discusses the commissioning and quality assurance (QA) methods for implementing a modified Stanford technique using a rotating harness system to position sedated pediatric patients treated with electrons to the total skin. Commissioning of pediatric TSEI consisted of absolute calibration, measurement of dosimetric parameters, and subsequent verification in a pediatric patient sized cylindrical phantom using radiographic film and optically stimulated luminance (OSL) dosimeters. The depth of dose penetration under TSEI treatment condition was evaluated using radiographic film sandwiched in the phantom and demonstrated a 2 cm penetration depth with the maximum dose located at the phantom surface. Dosimetry measurements on the cylindrical phantom and in-vivo measurements from the patients suggested that, the factor relating the skin and calibration point doses (i.e., the B-factor) was larger for the pediatric TSEI treatments as compared to adult TSEI treatments. Custom made equipment, including a rotating plate and harness, was fabricated and added to a standard total body irradiation stand and tested to facilitate patient setup under sedated condition. A pediatric TSEI QA program, consisting of daily output, energy, flatness, and symmetry measurements as well as in-vivo dosimetry verification for the first cycle was developed. With a long interval between pediatric TSEI cases, absolute dosimetry was also repeated as part of the QA program. In-vivo dosimetry for the first two infants showed that a dose of ± 10% of the prescription dose can be achieved over the entire patient body. Though pediatric leukemia cutis and the subsequent need for TSEI are rare, the ability to commission the technique on a modified TBI stand is appealing for clinical implementation and has been successfully used for the treatment of two pediatric patients at our institution.

A technique for pediatric total skin electron irradiation

PubMed Central

2012-01-01

Background Total skin electron irradiation (TSEI) is a special radiotherapy technique which has generally been used for treating adult patients with mycosis fungoides. Recently, two infants presented with leukemia cutis isolated to the skin requiring TSEI. This work discusses the commissioning and quality assurance (QA) methods for implementing a modified Stanford technique using a rotating harness system to position sedated pediatric patients treated with electrons to the total skin. Methods and Results Commissioning of pediatric TSEI consisted of absolute calibration, measurement of dosimetric parameters, and subsequent verification in a pediatric patient sized cylindrical phantom using radiographic film and optically stimulated luminance (OSL) dosimeters. The depth of dose penetration under TSEI treatment condition was evaluated using radiographic film sandwiched in the phantom and demonstrated a 2 cm penetration depth with the maximum dose located at the phantom surface. Dosimetry measurements on the cylindrical phantom and in-vivo measurements from the patients suggested that, the factor relating the skin and calibration point doses (i.e., the B-factor) was larger for the pediatric TSEI treatments as compared to adult TSEI treatments. Custom made equipment, including a rotating plate and harness, was fabricated and added to a standard total body irradiation stand and tested to facilitate patient setup under sedated condition. A pediatric TSEI QA program, consisting of daily output, energy, flatness, and symmetry measurements as well as in-vivo dosimetry verification for the first cycle was developed. With a long interval between pediatric TSEI cases, absolute dosimetry was also repeated as part of the QA program. In-vivo dosimetry for the first two infants showed that a dose of ± 10% of the prescription dose can be achieved over the entire patient body. Conclusion Though pediatric leukemia cutis and the subsequent need for TSEI are rare, the ability to commission the technique on a modified TBI stand is appealing for clinical implementation and has been successfully used for the treatment of two pediatric patients at our institution. PMID:22433063

Potential for reduced radiation‐induced toxicity using intensity‐modulated arc therapy for whole‐brain radiotherapy with hippocampal sparing

PubMed Central

Sood, Sumit; Lominska, Christopher; Kumar, Parvesh; Badkul, Rajeev; Jiang, Hongyu; Wang, Fen

2015-01-01

The purpose of this study was to retrospectively investigate the accuracy, plan quality, and efficiency of using intensity‐modulated arc therapy (IMAT) for whole brain radiotherapy (WBRT) patients with sparing not only the hippocampus (following RTOG 0933 compliance criteria) but also other organs at risk (OARs). A total of 10 patients previously treated with nonconformal opposed laterals whole‐brain radiotherapy (NC‐WBRT) were retrospectively replanned for hippocampal sparing using IMAT treatment planning. The hippocampus was volumetrically contoured on fused diagnostic T1‐weighted MRI with planning CT images and hippocampus avoidance zone (HAZ) was generated using a 5 mm uniform margin around the hippocampus. Both hippocampi were defined as one paired organ. Whole brain tissue minus HAZ was defined as the whole‐brain planning target volume (WB‐PTV). Highly conformal IMAT plans were generated in the Eclipse treatment planning system for Novalis TX linear accelerator consisting of high‐definition multileaf collimators (HD‐MLCs: 2.5 mm leaf width at isocenter) and 6 MV beam for a prescription dose of 30 Gy in 10 fractions following RTOG 0933 dosimetric criteria. Two full coplanar arcs with orbits avoidance sectors were used. In addition to RTOG criteria, doses to other organs at risk (OARs), such as parotid glands, cochlea, external/middle ear canals, skin, scalp, optic pathways, brainstem, and eyes/lens, were also evaluated. Subsequently, dose delivery efficiency and accuracy of each IMAT plan was assessed by delivering quality assurance (QA) plans with a MapCHECK device, recording actual beam‐on time and measuring planed vs. measured dose agreement using a gamma index. On IMAT plans, following RTOG 0933 dosimetric criteria, the maximum dose to WB‐PTV, mean WB‐PTV D2%, and mean WB‐PTV D98% were 34.9±0.3 Gy,33.2±0.4 Gy, and 26.0±0.4 Gy, respectively. Accordingly, WB‐PTV received the prescription dose of 30 Gy and mean V30 was 90.5%±0.5%. The D100%, and mean and maximum doses to hippocampus were 8.4±0.3 Gy,11.2±0.3 Gy, and 15.6±0.4 Gy, on average, respectively. The mean values of homogeneity index (HI) and conformity index (CI) were 0.23×0.02 and 0.96×0.02, respectively. The maximum point dose to WB‐PTV was 35.3 Gy, well below the optic pathway tolerance of 37.5 Gy. In addition, compared to NC‐WBRT, dose reduction of mean and maximum of parotid glands from IMAT were 65% and 50%, respectively. Ear canals mean and maximum doses were reduced by 26% and 12%, and mean and maximum scalp doses were reduced by 9 Gy (32%) and 2 Gy (6%), on average, respectively. The mean dose to skin was 9.7 Gy with IMAT plans compared to 16 Gy with conventional NC‐WBRT, demonstrating that absolute reduction of skin dose by a factor of 2. The mean values of the total number of monitor units (MUs) and actual beam on time were 719×44 and 2.34×0.14 min, respectively. The accuracy of IMAT QA plan delivery was (98.1±0.8) %, on average, with a 3%/3 mm gamma index passing rate criteria. All of these plans were considered clinically acceptable per RTOG 0933 criteria. IMAT planning provided highly conformal and homogenous plan with a fast and effective treatment option for WBRT patients, sparing not only hippocampi but also other OARs, which could potentially result in an additional improvement of the quality life (QoL). In the future, we plan to evaluate the clinical potential of IMAT planning and treatment option with hippocampal and other OARs avoidance in our patient's cohort and asses the QoL of the WBRT patients, as well as simultaneous integrated boost (SIB) for the brain metastases diseases. PACS number: 87 PMID:26699321

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Li-Min, E-mail: limin.sun@yahoo.com; Huang, Chih-Jen; Faculty of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung City, Taiwan

Acute skin reaction during adjuvant radiotherapy for breast cancer is an inevitable process, and its severity is related to the skin dose. A high–skin dose area can be speculated based on the isodose distribution shown on a treatment planning. To determine whether treatment planning can reflect high–skin dose location, 80 patients were collected and their skin doses in different areas were measured using a thermoluminescent dosimeter to locate the highest–skin dose area in each patient. We determined whether the skin dose is consistent with the highest-dose area estimated by the treatment planning of the same patient. The χ{sup 2} andmore » Fisher exact tests revealed that these 2 methods yielded more consistent results when the highest-dose spots were located in the axillary and breast areas but not in the inframammary area. We suggest that skin doses shown on the treatment planning might be a reliable and simple alternative method for estimating the highest skin doses in some areas.« less

SU-D-213-02: Characterization of the Effect of a New Commercial Transmission Detector On Radiotherapy Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheung, J; Morin, O

2015-06-15

Purpose: To evaluate the influence of a new commercial transmission detector on radiotherapy beams of various energies. Methods: A transmission detector designed for online treatment monitoring was characterized on a TrueBeam STx linear accelerator with 6MV, 6FFF, 10MV, and 10FFF beams. Measurements of beam characteristics including percentage depth doses (PDDs), inplane and crossplane off-axis profiles at different depths, transmission factors, and skin dose were acquired at field sizes of 3×3cm, 5×5m, 10×10cm, and 20×20cm at 100cm and 80cm source-to-surface distance (SSD). All measurements were taken with and without the transmission detector in the path of the beam. A CC04 chambermore » was used for all profile and transmission factor measurements. Skin dose was assessed at 100cm, 90cm, and 80cm SSD and using a variety of detectors (Roos and Markus parallel-plate chambers, and OSLD). Results: The PDDs showed small differences between the unperturbed and perturbed beams for both 100cm and 80cm SSD (≤4mm dmax difference and <1.2% average profile difference). The differences were larger for the flattened beams and at larger field sizes. The off-axis profiles showed similar trends. The penumbras looked similar with and without the transmission detector. Comparisons in the central 80% of the profile showed a maximum average (maximum) profile difference between all field sizes of 0.756% (1.535%) and 0.739% (3.682%) for 100cm and 80cm SSD, respectively. The average measured skin dose at 100cm (80cm) SSD for 10×10cm field size was <4% (<35%) dose increase for all energies. For 20×20cm field size, this value increased to <10% (≤45%). Conclusion: The transmission detector has minimal effect on the clinically relevant radiotherapy beams for IMRT and VMAT (field sizes 10×10cm and less). For larger field sizes, some perturbations are observable which would need to be assessed for clinical impact. The authors of this publication has research support from IBA Dosimetry.« less

Recommendations of the Spanish brachytherapy group (GEB) of Spanish Society of Radiation Oncology (SEOR) and the Spanish Society of Medical Physics (SEFM) for high-dose rate (HDR) non melanoma skin cancer brachytherapy.

PubMed

Rodríguez, S; Arenas, M; Gutierrez, C; Richart, J; Perez-Calatayud, J; Celada, F; Santos, M; Rovirosa, A

2018-04-01

Clinical indications of brachytherapy in non-melanoma skin cancers, description of applicators and dosimetry recommendations are described based on the literature review, clinical practice and experience of Spanish Group of Brachytherapy and Spanish Society of Medical Physics reported in the XIV Annual Consensus Meeting on Non Melanoma Skin Cancer Brachytherapy held in Benidorm, Alicante (Spain) on October 21st, 2016. All the recommendations for which consensus was achieved are highlighted in blue. Regular and small surfaces may be treated with Leipzig, Valencia, flap applicators or electronic brachytherapy (EBT). For irregular surfaces, customized molds or interstitial implants should be employed. The dose is prescribed at a maximum depth of 3-4 mm of the clinical target volume/planning target volume (CTV/PTV) in all cases except in flaps or molds in which 5 mm is appropriate. Interstitial brachytherapy should be used for CTV/PTV >5 mm. Different total doses and fraction sizes are used with very similar clinical and toxicity results. Hypofractionation is very useful twice or 3 times a week, being comfortable for patients and practical for Radiotherapy Departments. In interstitial brachytherapy 2 fractions twice a day are applied.

Doses of external exposure in Jordan house due to gamma-emitting natural radionuclides in building materials.

PubMed

Al-Jundi, J; Ulanovsky, A; Pröhl, G

2009-10-01

The use of building materials containing naturally occurring radionuclides as (40)K, (232)Th, and (238)U and their progeny results in external exposures of the residents of such buildings. In the present study, indoor dose rates for a typical Jordan concrete room are calculated using Monte Carlo method. Uniform chemical composition of the walls, floor and ceiling as well as uniform mass concentrations of the radionuclides in walls, floor and ceiling are assumed. Using activity concentrations of natural radionuclides typical for the Jordan houses and assuming them to be in secular equilibrium with their progeny, the maximum annual effective doses are estimated to be 0.16, 0.12 and 0.22 mSv a(-1) for (40)K, (232)Th- and (238)U-series, respectively. In a total, the maximum annual effective indoor dose due to external gamma-radiation is 0.50 mSv a(-1). Additionally, organ dose coefficients are calculated for all organs considered in ICRP Publication 74. Breast, skin and eye lenses have the maximum equivalent dose rate values due to indoor exposures caused by the natural radionuclides, while equivalent dose rates for uterus, colon (LLI) and small intestine are found to be the smallest. More specifically, organ dose rates (nSv a(-1)per Bq kg(-1)) vary from 0.044 to 0.060 for (40)K, from 0.44 to 0.60 for radionuclides from (238)U-series and from 0.60 to 0.81 for radionuclides from (232)Th-series. The obtained organ and effective dose conversion coefficients can be conveniently used in practical dose assessment tasks for the rooms of similar geometry and varying activity concentrations and local-specific occupancy factors.

DOE Office of Scientific and Technical Information (OSTI.GOV)

González, M. A. Pagnan, E-mail: miguelangel.pagnan@hotmail.com; Mitsoura, E., E-mail: meleni@uaemex.mx; Oviedo, J.O. Hernández

Mycosis fungoides is a cutaneous lymphoma that accounts for 2–3% of all lymphomas. Several clinical studies have demonstrated the effectiveness of TSEBT (Total Skin Electron Beam Therapy) in patients with mycosis fungoides. It is important to develop this technique and make it available to a larger number of patients in Mexico. Because large fields for electron TSEBT are required in order to cover the entire body of the patient, beam characterization at conventional treatment distances is not sufficient and a calibration distance of 500cm or higher is required. Materials and methods: Calibration of radiochromic Gafchromic® EBT2 film (RCF) for electronsmore » was performed in a solid water phantom (Scanditronix Wellhöfer) at a depth of 1.4cm and a Source Axis Distance (SAD) of 100cm. A polynomial fit was applied to the calibration curve, in order to obtain the equation relating dose response with optical density. The spatial distribution is obtained in terms of percentage of the dose, placing 3×3cm samples of RCF on the acrylic screen, which is placed in front of the patient in order to obtain maximum absorbed dose on the skin, covering an area of 200×100cm{sup 2}. The Percentage Depth Dose (PDD) curve was obtained placing RCF samples at depths of 0, 1, 1.2, 1.4, 1.5, 2, 3, 4, 5, 6, 7, 8 and 9cm in the solid water phantom, irradiated with an ELEKTA SINERGY Linear Accelerator electron beam, with an energy of 6 MeV, at a Source Skin Distance (SSD) of 500cm, with 1000MU = 100Gy, with a cone of 40×40cm and gantry angle of 90°. The RCFs were scanned on a flatbed scanner (EPSON EXPRESSION 10000 XL) and the images were processed with the ImageJ program using a region of interest (ROI) of 1×1cm{sup 2}. Results: The relative spatial dose distribution and the percentage depth dose for a SSD of 500±0.5cm, over an area of 200×100cm{sup 2} was obtained, resulting to an effective maximum dose depth (Z{sub ref}) for electrons of 1.4±0.05cm. Using the same experimental data, horizontal and vertical beam profiles were also graphed, showing a horizontal symmetry of ±035%, horizontal flatness of ±3.62%, vertical symmetry of ±2.1% and vertical flatness of ±14.2%. Conclusions: The electron beam was characterized and the data obtained were useful to determine the spatial dose distribution to a SSD of 500±0.5cm, in an area of 200×100cm{sup 2}. Dose profiles were obtained both horizontally and vertically, thus allowing to assess electron beam symmetry and flatness. PDD analysis up to a depth of 9±0.05cm, has made possible to establish the depth of electron penetration, assuring an only skin irradiation treatment.« less

Impact of cardiosynchronous brain pulsations on Monte Carlo calculated doses for synchrotron micro- and minibeam radiation therapy.

PubMed

Manchado de Sola, Francisco; Vilches, Manuel; Prezado, Yolanda; Lallena, Antonio M

2018-05-15

The purpose of this study was to assess the effects of brain movements induced by heartbeat on dose distributions in synchrotron micro- and minibeam radiation therapy and to develop a model to help guide decisions and planning for future clinical trials. The Monte Carlo code PENELOPE was used to simulate the irradiation of a human head phantom with a variety of micro- and minibeam arrays, with beams narrower than 100 μm and above 500 μm, respectively, and with radiation fields of 1 × 2 cm and 2 × 2 cm. The dose in the phantom due to these beams was calculated by superposing the dose profiles obtained for a single beam of 1 μm × 2 cm. A parameter δ, accounting for the total displacement of the brain during the irradiation and due to the cardiosynchronous pulsation, was used to quantify the impact on peak-to-valley dose ratios and the full width at half maximum. The difference between the maximum (at the phantom entrance) and the minimum (at the phantom exit) values of the peak-to-valley dose ratio reduces when the parameter δ increases. The full width at half maximum remains almost constant with depth for any δ value. Sudden changes in the two quantities are observed at the interfaces between the various tissues (brain, skull, and skin) present in the head phantom. The peak-to-valley dose ratio at the center of the head phantom reduces when δ increases, remaining above 70% of the static value only for minibeams and δ smaller than ∼200 μm. Optimal setups for brain treatments with synchrotron radiation micro- and minibeam combs depend on the brain displacement due to cardiosynchronous pulsation. Peak-to-valley dose ratios larger than 90% of the maximum values obtained in the static case occur only for minibeams and relatively large dose rates. © 2018 American Association of Physicists in Medicine.

Calculation of local skin doses with ICRP adult mesh-type reference computational phantoms

NASA Astrophysics Data System (ADS)

Yeom, Yeon Soo; Han, Haegin; Choi, Chansoo; Nguyen, Thang Tat; Lee, Hanjin; Shin, Bangho; Kim, Chan Hyeong; Han, Min Cheol

2018-01-01

Recently, Task Group 103 of the International Commission on Radiological Protection (ICRP) developed new mesh-type reference computational phantoms (MRCPs) for adult males and females in order to address the limitations of the current voxel-type reference phantoms described in ICRP Publication 110 due to their limited voxel resolutions and the nature of the voxel geometry. One of the substantial advantages of the MRCPs over the ICRP-110 reference phantoms is the inclusion of a 50-μm-thick radiosensitive skin basal-cell layer; however, a methodology for calculating the local skin dose (LSD), i.e., the maximum dose to the basal layer averaged over a 1-cm2 area, has yet to be developed. In the present study, a dedicated program for the LSD calculation with the MRCPs was developed based on the mean shift algorithm and the Geant4 Monte Carlo code. The developed program was used to calculate local skin dose coefficients (LSDCs) for electrons and alpha particles, which were then compared with the values given in ICRP Publication 116 that were produced with a simple tissue-equivalent cube model. The results of the present study show that the LSDCs of the MRCPs are generally in good agreement with the ICRP-116 values for alpha particles, but for electrons, significant differences are found at energies higher than 0.15 MeV. The LSDCs of the MRCPs are greater than the ICRP-116 values by as much as 2.7 times at 10 MeV, which is due mainly to the different curvature between realistic MRCPs ( i.e., curved) and the simple cube model ( i.e., flat).

Effect of treatment in fractionated schedules with the combination of x-irradiation and six cytotoxic drugs on the RIF-1 tumor and normal mouse skin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lelieveld, P.; Scoles, M.A.; Brown, J.M.

1985-01-01

RIF-1 tumors, implanted syngeneically in the gastrocnemius muscles of the right hind legs of C3H/Km mice, were treated either with X ray alone, drug alone, or drug and X ray combined. The drugs tested were bleomycin, BCNU, cis-diamminedichloro platinum, adriamycin, cyclophosphamide, and actinomycin-D. All drugs were administered either in the maximum tolerated dose or a dose that causes minimal tumor growth delay. Both drugs and X rays were administered either as a single dose or in five daily fractions. In addition to the single modality controls, seven different schedules of combined modalities were tested. Tumors were measured periodically after treatmentmore » in order that the day at which each tumor reached 4 times its initial cross-sectional area, i.e., its size at the time of treatment, could be determined. The effect of treatment on tumors was based upon excess growth delay (GD), i.e., T400% (treated)-T400% (untreated control). Treatment effects for the same combined modality schedules were also determined for normal skin, using the early skin reaction as an endpoint. Dose effect factors (DEF) were computed for all combined modality schedules and were based upon calculated radiation dose equivalents. We also calculated supra-additivity ratios, SR/sub I/ and SR/sub II/, therapeutic gain factors and adjusted therapeutic gain factors. The only drugs to produce significant supra-additivity with X rays were cis-Pt and cyclo.« less

In vitro dermal absorption of pyrethroid pesticides in human and rat skin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hughes, Michael F., E-mail: hughes.michaelf@epa.go; Edwards, Brenda C.

2010-07-15

Dermal exposure to pyrethroid pesticides can occur during manufacture and application. This study examined the in vitro dermal absorption of pyrethroids using rat and human skin. Dermatomed skin from adult male Long Evans rats or human cadavers was mounted in flow-through diffusion cells, and radiolabeled bifenthrin, deltamethrin or cis-permethrin was applied in acetone to the skin. Fractions of receptor fluid were collected every 4 h. At 24 h, the skins were washed with soap and water to remove unabsorbed chemical. The skin was then solubilized. Two additional experiments were performed after washing the skin; the first was tape-stripping the skinmore » and the second was the collection of receptor fluid for an additional 24 h. Receptor fluid, skin washes, tape strips and skin were analyzed for radioactivity. For rat skin, the wash removed 53-71% of the dose and 26-43% remained in the skin. The cumulative percentage of the dose at 24 h in the receptor fluid ranged from 1 to 5%. For human skin, the wash removed 71-83% of the dose and 14-25% remained in the skin. The cumulative percentage of the dose at 24 h in the receptor fluid was 1-2%. Tape-stripping removed 50-56% and 79-95% of the dose in rat and human skin, respectively, after the wash. From 24-48 h, 1-3% and about 1% of the dose diffused into the receptor fluid of rat and human skin, respectively. The pyrethroids bifenthrin, deltamethrin and cis-permethrin penetrated rat and human skin following dermal application in vitro. However, a skin wash removed 50% or more of the dose from rat and human skin. Rat skin was more permeable to the pyrethroids than human skin. Of the dose in skin, 50% or more was removed by tape-stripping, suggesting that permeation of pyrethroids into viable tissue could be impeded. The percentage of the dose absorbed into the receptor fluid was considerably less than the dose in rat and human skin. Therefore, consideration of the skin type used and fractions analyzed are important when using in vitro dermal absorption data for risk assessment.« less

Preoperative single fraction partial breast radiotherapy for early-stage breast cancer.

PubMed

Palta, Manisha; Yoo, Sua; Adamson, Justus D; Prosnitz, Leonard R; Horton, Janet K

2012-01-01

Several recent series evaluating external beam accelerated partial breast irradiation (PBI) have reported adverse cosmetic outcomes, possibly related to large volumes of normal tissue receiving near-prescription doses. We hypothesized that delivery of external beam PBI in a single fraction to the preoperative tumor volume would be feasible and result in a decreased dose to the uninvolved breast compared with institutional postoperative PBI historical controls. A total of 17 patients with unifocal Stage T1 breast cancer were identified. Contrast-enhanced subtraction magnetic resonance images were loaded into an Eclipse treatment planning system and used to define the target volumes. A "virtual plan" was created using four photon beams in a noncoplanar beam arrangement and optimized to deliver 15 Gy to the planning target volume. The median breast volume was 1,713 cm(3) (range: 1,014-2,140), and the median clinical target volume was 44 cm(3) (range: 26-73). In all cases, 100% of the prescription dose covered 95% of the clinical target volume. The median conformity index was 0.86 (range: 0.70-1.12). The median percentage of the ipsilateral breast volume receiving 100% and 50% of the prescribed dose was 3.8% (range: 2.2-6.9) and 13.3% (range: 7.5-20.8) compared with 18% (range: 3-42) and 53% (range: 24-65) in the institutional historical controls treated with postoperative external beam PBI (p = .002). The median maximum skin dose was 9 Gy. The median dose to 1 and 10 cm(3) of skin was 6.7 and 4.9 Gy. The doses to the heart and ipsilateral lung were negligible. Preoperative PBI resulted in a substantial reduction in ipsilateral breast tissue dose compared with postoperative PBI. The skin dose appeared reasonable, given the small volumes. A prospective Phase I trial evaluating this technique is ongoing. Copyright © 2012 Elsevier Inc. All rights reserved.

Real-time colour pictorial radiation monitoring during coronary angiography: effect on patient peak skin and total dose during coronary angiography.

PubMed

Wilson, Sharon M; Prasan, Ananth M; Virdi, Amy; Lassere, Marissa; Ison, Glenn; Ramsay, David R; Weaver, James C

2016-10-10

The aim of this study was to evaluate whether a real-time (RT) colour pictorial radiation dose monitoring system reduces patient skin and total radiation dose during coronary angiography and intervention. Patient demographics, procedural variables and radiation parameters were recorded before and after institution of the RT skin dose recording system. Peak skin dose as well as traditionally available measures of procedural radiation dose were compared. A total of 1,077 consecutive patients underwent coronary angiography, of whom 460 also had PCI. Institution of the RT skin dose recording system resulted in a 22% reduction in peak skin dose after accounting for confounding variables. Radiation dose reduction was most pronounced in those having PCI but was also seen over a range of subgroups including those with prior coronary artery bypass surgery, high BMI, and with radial arterial access. This was associated with a significant reduction in the number of patients placed at risk of skin damage. Similar reductions in parameters reflective of total radiation dose were also demonstrated after institution of RT radiation monitoring. Institution of an RT skin dose recording reduced patient peak skin and total radiation dose during coronary angiography and intervention. Consideration should be given to widespread adoption of this technology.

Monte Carlo skin dose simulation in intraoperative radiotherapy of breast cancer using spherical applicators.

PubMed

Moradi, F; Ung, N M; Khandaker, M U; Mahdiraji, G A; Saad, M; Abdul Malik, R; Bustam, A Z; Zaili, Z; Bradley, D A

2017-07-28

The relatively new treatment modality electronic intraoperative radiotherapy (IORT) is gaining popularity, irradiation being obtained within a surgically produced cavity being delivered via a low-energy x-ray source and spherical applicators, primarily for early stage breast cancer. Due to the spatially dramatic dose-rate fall off with radial distance from the source and effects related to changes in the beam quality of the low keV photon spectra, dosimetric account of the Intrabeam system is rather complex. Skin dose monitoring in IORT is important due to the high dose prescription per treatment fraction. In this study, modeling of the x-ray source and related applicators were performed using the Monte Carlo N-Particle transport code. The dosimetric characteristics of the model were validated against measured data obtained using an ionization chamber and EBT3 film as dosimeters. By using a simulated breast phantom, absorbed doses to the skin for different combinations of applicator size (1.5-5 cm) and treatment depth (0.5-3 cm) were calculated. Simulation results showed overdosing of the skin (>30% of prescribed dose) at a treatment depth of 0.5 cm using applicator sizes larger than 1.5 cm. Skin doses were significantly increased with applicator size, insofar as delivering 12 Gy (60% of the prescribed dose) to skin for the largest sized applicator (5 cm diameter) and treatment depth of 0.5 cm. It is concluded that the recommended 0.5-1 cm distance between the skin and applicator surface does not guarantee skin safety and skin dose is generally more significant in cases with the larger applicators. • Intrabeam x-ray source and spherical applicators were simulated and skin dose was calculated. • Skin dose for constant skin to applicator distance strongly depends on applicator size. • Use of larger applicators generally results in higher skin dose. • The recommended 0.5-1 cm skin to applicator distance does not guarantee skin safety.

In vivo skin dose measurement in breast conformal radiotherapy.

PubMed

Soleymanifard, Shokouhozaman; Aledavood, Seyed Amir; Noghreiyan, Atefeh Vejdani; Ghorbani, Mahdi; Jamali, Farideh; Davenport, David

2016-01-01

Accurate skin dose assessment is necessary during breast radiotherapy to assure that the skin dose is below the tolerance level and is sufficient to prevent tumour recurrence. The aim of the current study is to measure the skin dose and to evaluate the geometrical/anatomical parameters that affect it. Forty patients were simulated by TIGRT treatment planning system and treated with two tangential fields of 6 MV photon beam. Wedge filters were used to homogenise dose distribution for 11 patients. Skin dose was measured by thermoluminescent dosimeters (TLD-100) and the effects of beam incident angle, thickness of irradiated region, and beam entry separation on the skin dose were analysed. Average skin dose in treatment course of 50 Gy to the clinical target volume (CTV) was 36.65 Gy. The corresponding dose values for patients who were treated with and without wedge filter were 35.65 and 37.20 Gy, respectively. It was determined that the beam angle affected the average skin dose while the thickness of the irradiated region and the beam entry separation did not affect dose. Since the skin dose measured in this study was lower than the amount required to prevent tumour recurrence, application of bolus material in part of the treatment course is suggested for post-mastectomy advanced breast radiotherapy. It is more important when wedge filters are applied to homogenize dose distribution.

Proton depth dose distribution: 3-D calculation of dose distributions from solar flare irradiation

NASA Astrophysics Data System (ADS)

Leavitt, Dennis D.

1990-11-01

Relative depth dose distribution to the head from 3 typical solar flare proton events were calculated for 3 different exposure geometries: (1) single directional radiation incident upon a fixed head; (2) single directional radiation incident upon head rotating axially (2-D rotation); and (3) omnidirectional radiation incident upon head (3-D rotation). Isodose distributions in the transverse plane intersecting isocenter are presented for each of the 3 solar flare events in all 3 exposure geometries. In all 3 calculation configurations the maximum predicted dose occurred on the surface of the head. The dose at the isocenter of the head relative to the surface dose for the 2-D and 3-D rotation geometries ranged from 2 to 19 percent, increasing with increasing energy of the event. The calculations suggest the superficially located organs (lens of the eye and skin) are at greatest risk for the proton events studied here.

Construction of new skin models and calculation of skin dose coefficients for electron exposures

NASA Astrophysics Data System (ADS)

Yeom, Yeon Soo; Kim, Chan Hyeong; Nguyen, Thang Tat; Choi, Chansoo; Han, Min Cheol; Jeong, Jong Hwi

2016-08-01

The voxel-type reference phantoms of the International Commission on Radiological Protection (ICRP), due to their limited voxel resolutions, cannot represent the 50- μm-thick radiosensitive target layer of the skin necessary for skin dose calculations. Alternatively, in ICRP Publication 116, the dose coefficients (DCs) for the skin were calculated approximately, averaging absorbed dose over the entire skin depth of the ICRP phantoms. This approximation is valid for highly-penetrating radiations such as photons and neutrons, but not for weakly penetrating radiations like electrons due to the high gradient in the dose distribution in the skin. To address the limitation, the present study introduces skin polygon-mesh (PM) models, which have been produced by converting the skin models of the ICRP voxel phantoms to a high-quality PM format and adding a 50- μm-thick radiosensitive target layer into the skin models. Then, the constructed skin PM models were implemented in the Geant4 Monte Carlo code to calculate the skin DCs for external exposures of electrons. The calculated values were then compared with the skin DCs of the ICRP Publication 116. The results of the present study show that for high-energy electrons (≥ 1 MeV), the ICRP-116 skin DCs are, indeed, in good agreement with the skin DCs calculated in the present study. For low-energy electrons (< 1 MeV), however, significant discrepancies were observed, and the ICRP-116 skin DCs underestimated the skin dose as much as 15 times for some energies. Besides, regardless of the small tissue weighting factor of the skin ( w T = 0.01), the discrepancies in the skin dose were found to result in significant discrepancies in the effective dose, demonstarting that the effective DCs in ICRP-116 are not reliable for external exposure to electrons.

SU-E-T-489: Incorporating Skin Flash Into VMAT WBI: Impacts On Surface Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buele, A Bejarano; Tanny, S; Warrell, G

Purpose: Increased use of inverse planning limits the amount of skin flash in whole breast irradiation (WBI). Strategies to incorporate flash into inverse-planned treatments involve overriding air to the density of water or tissue. This introduces uncertainties to the superficial dose distribution, potentially degrading the coverage at the skin-bolus interface. We investigate the accuracy of various commonly used bolus materials to incorporate flash in VMAT WBI plans while minimizing the perturbation near the skin. Methods: We obtained a CT-simulation of an anthropomorphic phantom with a breast attachment. Three VMAT plans were created with different boluses: 1 cm of 1 g/cm{supmore » 3} bolus (Superflab), 1 cm of 0.65 g/cm{sup 3} bolus (wet towels), and 1 cm of g/cm{sup 3} bolus with 2 dose levels accounting for the difference between bolus and tissue density. The PTV was extended into the bolus, outside the patient body contour to incorporate flash. OSLDs were used to obtain surface doses at the medial, lateral and tip sites of the breast. Each plan was irradiated four times using CBCT for positioning and dosimeter localization. Results: The average thickness of the wet-towel bolus on delivery was 8 mm with a CBCT-measured density of 0.6 g/cm{sup 3}. OSLD measurements demonstrated good agreement with predicted doses from Pinnacle. Average deviations were −5.7%, −2.5%, and −2.6% for plans 1, 2, and 3, respectively. OSLDs placed at the medial and lateral portions of the breast showed the largest average deviations. The maximum recorded deviation from planned values was −8.6%. The largest dose fluctuations occurred near areas where the bolus failed to properly conform to the breast contour. Conclusion: Use of wet-towel bolus improved dose delivery accuracy compared to standard Superflab bolus. Areas of poor bolus conformity adversely affected dose delivery. We recommend the use of wet-towel bolus over Superflab bolus for VMAT WBI.« less

SU-F-T-22: Clinical Implications When Using TG-186 (ACE) Heterogeneity Software

DOE Office of Scientific and Technical Information (OSTI.GOV)

Likhacheva, A; Grade, E; Sadeghi, A

Purpose: The purpose of this study is to compare dosimetric calculations using traditional TG-43 formalism and Oncentra Brachy Advanced Collapsed cone Engine (ACE) TG-186 calculation algorithm in clinical setting. Methods: We analyzed dosimetry of four patients treated with accelerated partial breast irradiation using a multi-channel intracavitary device (SAVI). All patients were treated to 34 Gy in 10 fractions using a high-dose-rate (192) Ir source. The plans were designed and treated using the TG-43 model. ACE was used to assess the effect heterogeneity correction on various dosimetric parameters. Mass density was estimated using Hounsfield units. Results: Compared to TG-43 formalism, ACEmore » estimated lower doses to targets and organs at risk. The mean difference was 19.8% (range 15.3–24.1%) for PTV-eval V200, 12.0% (range 9.7–17.7%) for PTV-eval V150, 4.3% (range 3.3–6.5%) for PTV-eval D95, 3.3% (range 1.4–5.4%) for PTV-eval D90, 5.4% (range 2.9–9.9%) for maximum rib dose, and 5.7% (2.4–7.4%) for maximum skin dose. There was no correlation between the magnitude of the difference and the PTV-eval volume, air volume, or tissue-applicator conformance. Conclusion: Based on our preliminary study, the TG-43 algorithm appears to overestimate the dose to targets and organs at risk when compared to the ACE TG-186 software. We hypothesize that air adjacent to the SAVI struts contributes to lack of scatter thereby contributing a significant difference in dose calculation when using ACE. We believe that ACE calculation provides a more realistic isodose distribution than TG-43. We plan to further investigate the impact of heterogeneity correction on brachytherapy planning for a wide variety of clinical scenarios, include skin, cervix/uterus, prostate, and lung.« less

An analysis of interplanetary space radiation exposure for various solar cycles

NASA Technical Reports Server (NTRS)

Badhwar, G. D.; Cucinotta, F. A.; O'Neill, P. M.; Wilson, J. W. (Principal Investigator)

1994-01-01

The radiation dose received by crew members in interplanetary space is influenced by the stage of the solar cycle. Using the recently developed models of the galactic cosmic radiation (GCR) environment and the energy-dependent radiation transport code, we have calculated the dose at 0 and 5 cm water depth; using a computerized anatomical man (CAM) model, we have calculated the skin, eye and blood-forming organ (BFO) doses as a function of aluminum shielding for various solar minima and maxima between 1954 and 1989. These results show that the equivalent dose is within about 15% of the mean for the various solar minima (maxima). The maximum variation between solar minimum and maximum equivalent dose is about a factor of three. We have extended these calculations for the 1976-1977 solar minimum to five practical shielding geometries: Apollo Command Module, the least and most heavily shielded locations in the U.S. space shuttle mid-deck, center of the proposed Space Station Freedom cluster and sleeping compartment of the Skylab. These calculations, using the quality factor of ICRP 60, show that the average CAM BFO equivalent dose is 0.46 Sv/year. Based on an approach that takes fragmentation into account, we estimate a calculation uncertainty of 15% if the uncertainty in the quality factor is neglected.

Population PK Modeling and Target Attainment Simulations to Support Dosing of Ceftaroline Fosamil in Pediatric Patients With Acute Bacterial Skin and Skin Structure Infections and Community-Acquired Bacterial Pneumonia.

PubMed

Riccobene, Todd A; Khariton, Tatiana; Knebel, William; Das, Shampa; Li, James; Jandourek, Alena; Carrothers, Timothy J; Bradley, John S

2017-03-01

Ceftaroline, the active form of the prodrug ceftaroline fosamil, is approved for use in adults with community-acquired bacterial pneumonia (CABP) or acute bacterial skin and skin structure infections (ABSSSI) in the United States and for similar indications in Europe. Pharmacokinetic (PK) data from 5 pediatric (birth to <18 years) studies of ceftaroline fosamil were combined with PK data from adults to update a population PK model for ceftaroline and ceftaroline fosamil. This model, based on a data set including 305 children, was used to conduct simulations to estimate ceftaroline exposures and percentage of time that free drug concentrations were above the minimum inhibitory concentration (%fT>MIC) for pediatric dose regimens. With dose regimens of 8 mg/kg every 8 hours (q8h) in children aged 2 months to <2 years and 12 mg/kg (up to a maximum of 400 mg) q8h in children aged 2 years to <18 years or 600 mg q12h in children aged 12 to <18 years, >90% of children were predicted to achieve a target of 36% fT>MIC at an MIC of 2 mg/L, and >97% were predicted to achieve 44% fT>MIC at an MIC of 1 mg/L. Thus, high PK/pharmacodynamic target attainment would be maintained in children for targets associated with 1-log kill of Staphylococcus aureus and Streptococcus pneumoniae. The predicted ceftaroline exposures for these dose regimens were similar to those in adults given 600 mg q12h ceftaroline fosamil. This work contributed to the approval of dose regimens for children aged 2 months to <18 years by the FDA and EMA, which are presented. © 2016, The American College of Clinical Pharmacology.

SU-F-T-537: Prone Breast Accelerated Partial Breast Irradiation Using Non-Coplanar Volumetric Arc Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beninati, G; Barbiere, J; Godfrey, L

2016-06-15

Purpose: To demonstrate that Volumetric Modulated Arc Therapy (VMAT) can be an alternative technique to Brachytherapy Accelerated Partial Breast Irradiation (APBI) for treating large breasted women. The non-coplanar VMAT technique uses a commercially available couch and a small number of angles. This technique with the patient in the prone position can reduce high skin and critical structure doses in large breasted women, which are usually associated with Brachytherapy APBI. Methods: Philips Pinnacle treatment planning system with Smart Arc was used to plan a left sided laterally located excision cavity on a standard prone breast patient setup. Three thirty-degree arcs enteredmore » from the lateral side at respective couch angles of 345, 0, and 15 degrees. A fourth thirty degree arc beam entered from the medial side at a couch angle of 0 degrees. The arcs were selected to avoid critical structures as much as possible. A test run was then performed to verify that the beams did not collide with the patient nor support structures. NSABP B-39/RTOG 0413 protocol guidelines were used for dose prescription, normal tissue, and target definition. Results: Dose Volume Histogram analysis indicated that all parameters were equal or better than RTOG recommendations. Of particular note regarding the plan quality:1.(a) For a prescribed dose of 3850cGy the PTV-EVAL target volume receiving 100 percent of the dose(V100) was 93; protocol recommendation is V90 > 90 percent. (b) Maximum dose was 110 percent versus the allowed 120 percent .2. Uninvolved percentage of normal breast V100 and V50 were 17 and 47 versus allowed 35 and 60 percent respectively.3. For the skin, V100 was 5.7cc and the max dose to 0.1 cc was 4190cGy. Conclusion: Prone Breast non-coplanar VMAT APBI can achieve better skin cosmesis and lower critical structure doses than Brachytherapy APBI.« less

Nitroxides are more efficient inhibitors of oxidative damage to calf skin collagen than antioxidant vitamins.

PubMed

Venditti, Elisabetta; Scirè, Andrea; Tanfani, Fabio; Greci, Lucedio; Damiani, Elisabetta

2008-01-01

Reactive oxygen species generated upon UV-A exposure appear to play a major role in dermal connective tissue transformations including degradation of skin collagen. Here we investigate on oxidative damage to collagen achieved by exposure to (i) UV-A irradiation and to (ii) AAPH-derived radicals and on its possible prevention using synthetic and natural antioxidants. Oxidative damage was identified through SDS-PAGE, circular dichroism spectroscopy and quantification of protein carbonyl residues. Collagen (2 mg/ml) exposed to UV-A and to AAPH-derived radicals was degraded in a time- and dose-dependent manner. Upon UV-A exposure, maximum damage was observable at 730 kJ/m2 UV-A, found to be equivalent to roughly 2 h of sunshine, while exposure to 5 mM AAPH for 2 h at 50 degrees C lead to maximum collagen degradation. In both cases, dose-dependent protection was achieved by incubation with muM concentrations of nitroxide radicals, where the extent of protection was shown to be dictated by their structural differences whereas the vitamins E and C proved less efficient inhibitors of collagen damage. These results suggest that nitroxide radicals may be able to prevent oxidative injury to dermal tissues in vivo alternatively to commonly used natural antioxidants.

SU-F-T-151: Measurement Evaluation of Skin Dose in Scanning Proton Beam Therapy for Breast Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, J; Nichols, E; Strauss, D

Purpose: To measure the skin dose and compare it with the calculated dose from a treatment planning system (TPS) for breast cancer treatment using scanning proton beam therapy (SPBT). Methods: A single en-face-beam SPBT plan was generated by a commercial TPS for two breast cancer patients. The treatment volumes were the entire breasts (218 cc and 1500 cc) prescribed to 50.4 Gy (RBE) in 28 fractions. A range shifter of 5 cm water equivalent thickness was used. The organ at risk (skin) was defined to be 5 mm thick from the surface. The skin doses were measured in water withmore » an ADCL calibrated parallel plate (PP) chamber. The measured data were compared with the values calculated in the TPS. Skin dose calculations can be subject to uncertainties created by the definition of the external contour and the limitations of the correction based algorithms, such as proton convolution superposition. Hence, the external contours were expanded by 0, 3 mm and 1 cm to include additional pixels for dose calculation. In addition, to examine the effects of the cloth gown on the skin dose, the skin dose measurements were conducted with and without gown. Results: On average the measured skin dose was 4% higher than the calculated values. At deeper depths, the measured and calculated doses were in better agreement (< 2%). Large discrepancy occur for the dose calculated without external expansion due to volume averaging. The addition of the gown only increased the measured skin dose by 0.4%. Conclusion: The implemented TPS underestimated the skin dose for breast treatments. Superficial dose calculation without external expansion would result in large errors for SPBT for breast cancer.« less

Estimation of human percutaneous bioavailability for two novel brominated flame retardants, 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (EH-TBB) and bis(2-ethylhexyl) tetrabromophthalate (BEH-TEBP).

PubMed

Knudsen, Gabriel A; Hughes, Michael F; Sanders, J Michael; Hall, Samantha M; Birnbaum, Linda S

2016-11-15

2-Ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB) and bis(2-ethylhexyl)tetrabromophthalate (BEH-TEBP) are novel brominated flame retardants used in consumer products. A parallelogram approach was used to predict human dermal absorption and flux for EH-TBB and BEH-TEBP. [ 14 C]-EH-TBB or [ 14 C]-BEH-TEBP was applied to human or rat skin at 100nmol/cm 2 using a flow-through system. Intact rats received analogous dermal doses. Treated skin was washed and tape-stripped to remove "unabsorbed" [ 14 C]-radioactivity after continuous exposure (24h). "Absorbed" was quantified using dermally retained [ 14 C]-radioactivity; "penetrated" was calculated based on [ 14 C]-radioactivity in media (in vitro) or excreta+tissues (in vivo). Human skin absorbed EH-TBB (24±1%) while 0.2±0.1% penetrated skin. Rat skin absorbed more (51±10%) and was more permeable (2±0.5%) to EH-TBB in vitro; maximal EH-TBB flux was 11±7 and 102±24pmol-eq/cm 2 /h for human and rat skin, respectively. In vivo, 27±5% was absorbed and 13% reached systemic circulation after 24h (maximum flux was 464±65pmol-eq/cm 2 /h). BEH-TEBP in vitro penetrance was minimal (<0.01%) for rat or human skin. BEH-TEBP absorption was 12±11% for human skin and 41±3% for rat skin. In vivo, total absorption was 27±9%; 1.2% reached systemic circulation. In vitro maximal BEH-TEBP flux was 0.3±0.2 and 1±0.3pmol-eq/cm 2 /h for human and rat skin; in vivo maximum flux for rat skin was 16±7pmol-eq/cm 2 /h. EH-TBB was metabolized in rat and human skin to tetrabromobenzoic acid. BEH-TEBP-derived [ 14 C]-radioactivity in the perfusion media could not be characterized. <1% of the dose of EH-TBB and BEH-TEHP is estimated to reach the systemic circulation following human dermal exposure under the conditions tested. 2-Ethylhexyl 2,3,4,5-tetrabromobenzoate (PubChem CID: 71316600; CAS No. 183658-27-7 FW: 549.92g/mol logP est : 7.73-8.75 (12)) Abdallah et al., 2015a. Other published abbreviations for 2-ethylhexyl-2,3,4,5-tetrabromobenzoate are TBB EHTeBB or EHTBB Abdallah and Harrad, 2011. bis(2-ethylhexyl) tetrabromophthalate (PubChem CID: 117291; CAS No. 26040-51-7 FW: 706.14g/mol logP est : 9.48-11.95 (12)). Other published abbreviations for bis(2-ethylhexyl)tetrabromophthalate are TeBrDEPH TBPH or BEHTBP. Published by Elsevier Inc.

Monte Carlo skin dose simulation in intraoperative radiotherapy of breast cancer using spherical applicators

NASA Astrophysics Data System (ADS)

Moradi, F.; Ung, N. M.; Khandaker, M. U.; Mahdiraji, G. A.; Saad, M.; Malik, R. Abdul; Bustam, A. Z.; Zaili, Z.; Bradley, D. A.

2017-08-01

The relatively new treatment modality electronic intraoperative radiotherapy (IORT) is gaining popularity, irradiation being obtained within a surgically produced cavity being delivered via a low-energy x-ray source and spherical applicators, primarily for early stage breast cancer. Due to the spatially dramatic dose-rate fall off with radial distance from the source and effects related to changes in the beam quality of the low keV photon spectra, dosimetric account of the Intrabeam system is rather complex. Skin dose monitoring in IORT is important due to the high dose prescription per treatment fraction. In this study, modeling of the x-ray source and related applicators were performed using the Monte Carlo N-Particle transport code. The dosimetric characteristics of the model were validated against measured data obtained using an ionization chamber and EBT3 film as dosimeters. By using a simulated breast phantom, absorbed doses to the skin for different combinations of applicator size (1.5-5 cm) and treatment depth (0.5-3 cm) were calculated. Simulation results showed overdosing of the skin (>30% of prescribed dose) at a treatment depth of 0.5 cm using applicator sizes larger than 1.5 cm. Skin doses were significantly increased with applicator size, insofar as delivering 12 Gy (60% of the prescribed dose) to skin for the largest sized applicator (5 cm diameter) and treatment depth of 0.5 cm. It is concluded that the recommended 0.5-1 cm distance between the skin and applicator surface does not guarantee skin safety and skin dose is generally more significant in cases with the larger applicators. Highlights: • Intrabeam x-ray source and spherical applicators were simulated and skin dose was calculated. • Skin dose for constant skin to applicator distance strongly depends on applicator size. • Use of larger applicators generally results in higher skin dose. • The recommended 0.5-1 cm skin to applicator distance does not guarantee skin safety.

Dosimetric feasibility of magnetic resonance imaging-guided tri-cobalt 60 preoperative intensity modulated radiation therapy for soft tissue sarcomas of the extremity.

PubMed

Kishan, Amar U; Cao, Minsong; Mikaeilian, Argin G; Low, Daniel A; Kupelian, Patrick A; Steinberg, Michael L; Kamrava, Mitchell

2015-01-01

The purpose of this study was to investigate the dosimetric differences of delivering preoperative intensity modulated radiation therapy (IMRT) to patients with soft tissue sarcomas of the extremity (ESTS) with a teletherapy system equipped with 3 rotating (60)Co sources and a built-in magnetic resonance imaging and with standard linear accelerator (LINAC)-based IMRT. The primary study population consisted of 9 patients treated with preoperative radiation for ESTS between 2008 and 2014 with LINAC-based static field IMRT. LINAC plans were designed to deliver 50 Gy in 25 fractions to 95% of the planning target volume (PTV). Tri-(60)Co system IMRT plans were designed with ViewRay system software. Tri-(60)Co-based IMRT plans achieved equivalent target coverage and dosimetry for organs at risk (long bone, skin, and skin corridor) compared with LINAC-based IMRT plans. The maximum and minimum PTV doses, heterogeneity indices, and ratio of the dose to 50% of the volume were equivalent for both planning systems. One LINAC plan violated the maximum bone dose constraint, whereas none of the tri-(60)Co plans did. Using a tri-(60)Co system, we were able to achieve equivalent dosimetry to the PTV and organs at risk for patients with ESTS compared with LINAC-based IMRT plans. The tri-(60)Co system may be advantageous over current treatment platforms by allowing PTV reduction and by elimination of the additional radiation dose associated with daily image guidance, but this needs to be evaluated prospectively. Copyright © 2015 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.

Chemopreventive effect of Lagenaria siceraria in two stages DMBA plus croton oil induced skin papillomagenesis.

PubMed

Kumar, Navneet; Kale, Raosaheb K; Tiku, Ashu B

2013-01-01

Cancer chemoprevention is a dietary or therapeutic strategy to prevent, suppress, or delay carcinogenesis either at initiation or progression level with nontoxic agents. Use of natural dietary compounds has been a major chemopreventive approach to modulate tumorigenic pathways. In the present study, we have evaluated Lagenaria siceraria (bottle gourd), a common vegetable of Indian household for its chemomodulatory potential. The fruit has been used in traditional medicine for a very long time for health benefits and to cure pain, ulcers, fever, cough, asthma, and other bronchial disorders. However, despite its reported beneficial effect the chemo modulatory potential of this plant has not been reported. Therefore chemopreventive effect of bottle gourd juice (BGJ) was studied against 7,12-dimethylbenz(a)anthracene (DMBA) plus croton oil induced skin papillomagenesis in Swiss albino mice. The effect was studied both at antiinitiation and antiinitiation/promotion level followed by histopathological study. A dose of 2.5% and 5% given in drinking water showed significant decrease in papilloma number, papilloma incidence, papilloma multiplicity, papilloma latency, papilloma volume, and papilloma size in different size range. Histopathological study showed chemopreventive effect by minimizing loss of stratification, a decrease in number of epithelial layers, reducing dermal infiltration and protection for various cytoplasmic changes. Higher dose of BGJ was found to be more effective than lower dose and the chemopreventive effect was maximum for antiinitiation/promotion treatment. Altogether, this study reports the chemopreventive effect of Lagenaria siceraria on skin papillomagenesis for the first time and suggests that its consumption may help in suppression of skin cancer.

Synergistic Skin Penetration Enhancer and Nanoemulsion Formulations Promote the Human Epidermal Permeation of Caffeine and Naproxen.

PubMed

Abd, Eman; Namjoshi, Sarika; Mohammed, Yousuf H; Roberts, Michael S; Grice, Jeffrey E

2016-01-01

We examined the extent of skin permeation enhancement of the hydrophilic drug caffeine and lipophilic drug naproxen applied in nanoemulsions incorporating skin penetration enhancers. Infinite doses of fully characterized oil-in-water nanoemulsions containing the skin penetration enhancers oleic acid or eucalyptol as oil phases and caffeine (3%) or naproxen (2%) were applied to human epidermal membranes in Franz diffusion cells, along with aqueous control solutions. Caffeine and naproxen fluxes were determined over 8 h. Solute solubility in the formulations and in the stratum corneum (SC), as well as the uptake of product components into the SC were measured. The nanoemulsions significantly enhanced the skin penetration of caffeine and naproxen, compared to aqueous control solutions. Caffeine maximum flux enhancement was associated with a synergistic increase in both caffeine SC solubility and skin diffusivity, whereas a formulation-increased solubility in the SC was the dominant determinant for increased naproxen fluxes. Enhancements in SC solubility were related to the uptake of the formulation excipients containing the active compounds into the SC. Enhanced skin penetration in these systems is largely driven by uptake of formulation excipients containing the active compounds into the SC with impacts on SC solubility and diffusivity.

[Characterization of a diode system for in vivo dosimetry with electron beams].

PubMed

Ragona, R; Rossetti, V; Lucio, F; Anglesio, S; Giglioli, F R

2001-10-01

Current quality assurance regulation stresses the basic role of in vivo dosimetry. Our study evaluates the usefulness and reliability of semiconductor diodes in determining the electron absorbed dose. P-type EDE semiconductor detectors were irradiated with electron beams of different energies produced by a CGR Saturn Therac 20. The diode and ionization chamber response were compared, and effect of energy value, collimator opening, source skin distance and gantry angle on diode response was studied. Measurements show a maximum increment of about 20% in diode response increasing the beam energy (6-20 MeV). The response also increases with: collimator opening, reaching 5% with field sizes larger than 10x10 cm2 (with the exception of 20 MeV energy); SSD increase (with a maximum of 8% for 20 MeV); transversal gantry incidence, compared with the diode longitudinal axis; it does not affect the response in the interval of +/- 45 degrees. Absorbed dose attenuation at dmax, due to the presence of diode on the axis of the beam as a function of electron energy was also determined : the maximum attenuation value is 15% in 6 MeV electron beams. A dose calculation algorithm, taking into account diode response dependence was outlined. In vivo dosimetry was performed in 92 fields for 80 patients, with an agreement of +/-4 % (1 SD) between prescribed and measured dose. It is possible to use the EDE semiconductor detectors on a quality control program of dose delivery for electron beam therapy, but particular attention should be paid to the beam incidence angle and diode dose attenuation.

GONADAL AND BONE MARROW DOSE IN MEDICAL DIAGNOSTIC RADIOLOGY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahmoud, K.A.; Mahfouz, M.M.; Mahmoud, M.E.

1961-08-01

Measurements were made of the active mean bone marrow, integral bone marrow, gonadal, and maximum skin doses from diagnostic x-ray procedures used in Cairo University Hospitals. The active mean marrow dose in cervical, dorsal, and lumbar spine diagnostic exposures were: found to be somewhat smaller than those reported by some western couatries. One of the most striking results of the survey was the relatively high values of the urinary tract cases investigated diagnostically; owing to the high incidence of urinary tract Schistosomiasis. The gonadal dose delivered to males and females was found to be almosi negligible for all diagnostic investigationsmore » of the spine, except for the lumbo-dorsal region which was within the range 50 to 500 mrads. It was also found that the gonadal dose was significant in investigations of the lower gastrointestinal tract, gall bladder, and urinary tract. (P.C.H.)« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, J; Kim, J; Park, S

Purpose: To investigate exposure outside the treatment field when treating breast cancer with tri-Co-60 magnetic resonance (MR) image guided radiation therapy (IGRT) system. Methods: A total of 7 patients who treated with accelerated partial breast irradiation (APBI) technique were selected prospectively for this study (prescription dose = 38.5 Gy in 10 fractions). Every patient treated with two plans, one was an initial plan and the other was an adaptive plan generated after finishing 5 fractions (a total of 14 plans). Every plan was calculated with and without magnetic field in the treatment planning system. The EBT3 films were attached onmore » the front and the back of 1 cm bolus, and then it was placed on the patient body vertically to cover patient’s jaw and shoulder. After measurements, the maximum point dose and the mean dose of whole area of EBT3 film were acquired. Results: In the treatment plan with magnetic field, low dose stream outside the patient body was observed, almost reaching the patient’s jaw or shoulder, while it was not observed without magnetic field. The average values of the measured maximum and mean doses at the front of bolus were 30.1 ± 11.1 cGy (7.8% of the daily dose) and 14.7 ± 3.3 cGy (3.8%), respectively. At the back of bolus, those values were 6.0 ± 1.9 cGy (1.6%) and 5.1 ± 1.6 cGy (1.3%), respectively. The largest maximum dose at the front was 54.2 cGy (14.1%) while it was 20.7 cGy (5.4%) at the back. The average decrease of the maximum dose by the bolus was 24.0 ± 11.0 cGy. Conclusion: Due to magnetic field, dose stream outside the patient body can be generated during breast cancer treatment with the tri-Co-60 MR-IGRT system. Since this dose stream irradiated skin outside the treatment field, it should be shielded. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2015R1C1A1A01054192).« less

TLD extrapolation for skin dose determination in vivo.

PubMed

Kron, T; Butson, M; Hunt, F; Denham, J

1996-11-01

Prediction of skin reactions requires knowledge of the dose at various depths in the human skin. Using thermoluminescence dosimeters of three different thicknesses, the dose can be extrapolated to the surface and interpolated between the different depths. A TLD holder was designed for these TLD extrapolation measurements on patients during treatment which allowed measurements of entrance and exit skin dose with a day to day variability of +/-7% (S.D. of mean reading). In a pilot study on 18 patients undergoing breast irradiation, it was found that the angle of incidence of the radiation beam is the most significant factor influencing skin entrance dose. In most of these measurements the beam exit dose contributed 50% more to the surface dose than the entrance dose.

Skin-sparing Helical Tomotherapy vs 3D-conformal Radiotherapy for Adjuvant Breast Radiotherapy: In Vivo Skin Dosimetry Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capelle, Lisa; Warkentin, Heather; MacKenzie, Marc

Purpose: We investigated whether treatment-planning system (TPS)-calculated dose accurately reflects skin dose received for patients receiving adjuvant breast radiotherapy (RT) with standard three-dimensional conformal RT (3D-CRT) or skin-sparing helical tomotherapy (HT). Methods and Materials: Fifty patients enrolled in a randomized controlled trial investigating acute skin toxicity from adjuvant breast RT with 3D-CRT compared to skin-sparing HT, where a 5-mm strip of ipsilateral breast skin was spared. Thermoluminescent dosimetry or optically stimulated luminescence measurements were made in multiple locations and were compared to TPS-calculated doses. Skin dosimetric parameters and acute skin toxicity were recorded in these patients. Results: With HT theremore » was a significant correlation between calculated and measured dose in the medial and lateral ipsilateral breast (r = 0.67, P<.001; r = 0.44, P=.03, respectively) and the medial and central contralateral breast (r = 0.73, P<.001; r = 0.88, P<.001, respectively). With 3D-CRT there was a significant correlation in the medial and lateral ipsilateral breast (r = 0.45, P=.03; r = 0.68, P<.001, respectively); the medial and central contralateral breast (r = 0.62, P=.001; r = 0.86, P<.001, respectively); and the mid neck (r = 0.42, P=.04, respectively). On average, HT-calculated dose overestimated the measured dose by 14%; 3D-CRT underestimated the dose by 0.4%. There was a borderline association between highest measured skin dose and moist desquamation (P=.05). Skin-sparing HT had greater skin homogeneity (homogeneity index of 1.39 vs 1.65, respectively; P=.005) than 3D-CRT plans. HT plans had a lower skin{sub V50} (1.4% vs 5.9%, respectively; P=.001) but higher skin{sub V40} and skin{sub V30} (71.7% vs 64.0%, P=.02; and 99.0% vs 93.8%, P=.001, respectively) than 3D-CRT plans. Conclusion: The 3D-CRT TPS more accurately reflected skin dose than the HT TPS, which tended to overestimate dose received by 14% in patients receiving adjuvant breast RT.« less

A phase 1 dose-escalation and expansion study of binimetinib (MEK162), a potent and selective oral MEK1/2 inhibitor

PubMed Central

Bendell, Johanna C; Javle, Milind; Bekaii-Saab, Tanios S; Finn, Richard S; Wainberg, Zev A; Laheru, Daniel A; Weekes, Colin D; Tan, Benjamin R; Khan, Gazala N; Zalupski, Mark M; Infante, Jeffrey R; Jones, Suzanne; Papadopoulos, Kyriakos P; Tolcher, Anthony W; Chavira, Renae E; Christy-Bittel, Janna L; Barrett, Emma; Patnaik, Amita

2017-01-01

Background: Binimetinib (MEK162; ARRY-438162) is a potent and selective oral MEK 1/2 inhibitor. This phase 1 study determined the maximum tolerated dose (MTD), safety, pharmacokinetic and pharmacodynamic profiles, and preliminary anti-tumour activity of binimetinib in patients with advanced solid tumours, with expansion cohorts of patients with biliary cancer or KRAS- or BRAF-mutant colorectal cancer. Methods: Binimetinib was administered twice daily. Expansion cohorts were enroled after MTD determination following a 3+3 dose-escalation design. Pharmacokinetic properties were determined from plasma samples. Tumour samples were assessed for mutations in RAS, RAF, and other relevant genes. Pharmacodynamic properties were evaluated in serum and skin punch biopsy samples. Results: Ninety-three patients received binimetinib (dose-escalation phase, 19; expansion, 74). The MTD was 60 mg twice daily, with dose-limiting adverse events (AEs) of dermatitis acneiform and chorioretinopathy. The dose for expansion patients was subsequently decreased to 45 mg twice daily because of the frequency of treatment-related ocular toxicity at the MTD. Common AEs across all dose levels included rash (81%), nausea (56%), vomiting (52%), diarrhoea (51%), peripheral oedema (46%), and fatigue (43%); most were grade 1/2. Dose-proportional increases in binimetinib exposure were observed and target inhibition was demonstrated in serum and skin punch biopsy samples. Three patients with biliary cancer had objective responses (one complete and two partial). Conclusions: Binimetinib demonstrated a manageable safety profile, target inhibition, and dose-proportional exposure. The 45 mg twice daily dose was identified as the recommended phase 2 dose. The three objective responses in biliary cancer patients are encouraging and support further evaluation in this population. PMID:28152546

Radiation exposure during scoliosis screening radiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nottage, W.M.; Waugh, T.R.; McMaster, W.C.

Screening programs to detect scoliosis in the adolescent population are active in most communities. Two percent of children screened will be referred for treatment or observation. Increasing concern has been voiced regarding the amount of the potential effects of the radiation administered in such screening programs. Radiation dosage was directly measured on 19 children participating in an established school scoliosis screening program, using lithium fluoride thermoluminescence dosimeters. The mean gonadal doses are measured to be 19 mrem in males and estimated at a maximum 95 mrem in females. The mean entrance skin dose was 174 mrem. A lack of uniformitymore » in the radiographic techniques employed by individual technician was identified. The measured doses were within established acceptable limits and are comparable or below the average dose of 100 mrem received annually by the general public from the environment.« less

Irradiation of human skin by short wavelength ultraviolet radiation (100--290 nm) (u.v.C): increased concentrations of arachidonic acid and prostaglandines E2 and F2alpha.

PubMed Central

Camp, R D; Greaves, M W; Hensby, C N; Plummer, N A; Warin, A P

1978-01-01

1. Human abdominal skin was irradiated with six times the minimal erythema dose of ultraviolet C (100--290 nm) radiation. Erythema appeared at 3 h, was of moderate degree by 6 h and was maximal at 12--24 h. It was reduced at 48 h and by 72 h had disappeared. 2. A suction bulla technique was used for the recovery of exudate from normal and inflamed skin at 6, 18, 24 and 48 h after irradiation. 3. Prostaglandin-like activity, estimated by bioassay, showed maximum increase at 18 h, when erythema was also maximum. PGF 2alpha, measured by both radioimmunoassay and by combined gas-liquid chromatography--gas spectrometry, followed a similar time course then fell to normal, or near normal, levels at 48 h. 4. Prostaglandin E2 and arachidonic acid concentrations, measured by gas chromatography--mass spectrometry, were maximally raised at 18--24 h. At 48 h, when some erythema was still present, though reduced, prostaglandin E2 concentrations were still raised above control values. 5. The results provide direct evidence in support of the view that the erythma following irradiation of human skin by u.v.C involves activation of arachidonic acid metabolism. However, the relationship between the erythema and increased prostaglandin activity is not fully understood. PMID:678391

Skin dose measurements using MOSFET and TLD for head and neck patients treated with tomotherapy.

PubMed

Kinhikar, Rajesh A; Murthy, Vedang; Goel, Vineeta; Tambe, Chandrashekar M; Dhote, Dipak S; Deshpande, Deepak D

2009-09-01

The purpose of this work was to estimate skin dose for the patients treated with tomotherapy using metal oxide semiconductor field-effect transistors (MOSFETs) and thermoluminescent dosimeters (TLDs). In vivo measurements were performed for two head and neck patients treated with tomotherapy and compared to TLD measurements. The measurements were subsequently carried out for five days to estimate the inter-fraction deviations in MOSFET measurements. The variation between skin dose measured with MOSFET and TLD for first patient was 2.2%. Similarly, the variation of 2.3% was observed between skin dose measured with MOSFET and TLD for second patient. The tomotherapy treatment planning system overestimated the skin dose as much as by 10-12% when compared to both MOSFET and TLD. However, the MOSFET measured patient skin doses also had good reproducibility, with inter-fraction deviations ranging from 1% to 1.4%. MOSFETs may be used as a viable dosimeter for measuring skin dose in areas where the treatment planning system may not be accurate.

Surface dosimetry for breast radiotherapy in the presence of immobilization cast material

NASA Astrophysics Data System (ADS)

Kelly, Andrew; Hardcastle, Nicholas; Metcalfe, Peter; Cutajar, Dean; Quinn, Alexandra; Foo, Kerwyn; Cardoso, Michael; Barlin, Sheree; Rosenfeld, Anatoly

2011-02-01

Curative breast radiotherapy typically leaves patients with varying degrees of cosmetic damage. One problem interfering with cosmetically acceptable breast radiotherapy is the external contour for large pendulous breasts which often results in high doses to skin folds. Thermoplastic casts are often employed to secure the breasts to maintain setup reproducibility and limit the presence of skin folds. This paper aims to determine changes in surface dose that can be attributed to the use of thermoplastic immobilization casts. Skin dose for a clinical hybrid conformal/IMRT breast plan was measured using radiochromic film and MOSFET detectors at a range of water equivalent depths representative of the different skin layers. The radiochromic film was used as an integrating dosimeter, while the MOSFETs were used for real-time dosimetry to isolate the contribution of skin dose from individual IMRT segments. Strips of film were placed at various locations on the breast and the MOSFETs were used to measure skin dose at 16 positions spaced along the film strips for comparison of data. The results showed an increase in skin dose in the presence of the immobilization cast of up to 45.7% and 62.3% of the skin dose without the immobilization cast present as measured with Gafchromic EBT film and MOSFETs, respectively. The increase in skin dose due to the immobilization cast varied with the angle of beam incidence and was greatest when the beam was normally incident on the phantom. The increase in surface dose with the immobilization cast was greater under entrance dose conditions compared to exit dose conditions.

The effect of head size/shape, miscentering, and bowtie filter on peak patient tissue doses from modern brain perfusion 256-slice CT: How can we minimize the risk for deterministic effects?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perisinakis, Kostas; Seimenis, Ioannis; Tzedakis, Antonis

Purpose: To determine patient-specific absorbed peak doses to skin, eye lens, brain parenchyma, and cranial red bone marrow (RBM) of adult individuals subjected to low-dose brain perfusion CT studies on a 256-slice CT scanner, and investigate the effect of patient head size/shape, head position during the examination and bowtie filter used on peak tissue doses. Methods: The peak doses to eye lens, skin, brain, and RBM were measured in 106 individual-specific adult head phantoms subjected to the standard low-dose brain perfusion CT on a 256-slice CT scanner using a novel Monte Carlo simulation software dedicated for patient CT dosimetry. Peakmore » tissue doses were compared to corresponding thresholds for induction of cataract, erythema, cerebrovascular disease, and depression of hematopoiesis, respectively. The effects of patient head size/shape, head position during acquisition and bowtie filter used on resulting peak patient tissue doses were investigated. The effect of eye-lens position in the scanned head region was also investigated. The effect of miscentering and use of narrow bowtie filter on image quality was assessed. Results: The mean peak doses to eye lens, skin, brain, and RBM were found to be 124, 120, 95, and 163 mGy, respectively. The effect of patient head size and shape on peak tissue doses was found to be minimal since maximum differences were less than 7%. Patient head miscentering and bowtie filter selection were found to have a considerable effect on peak tissue doses. The peak eye-lens dose saving achieved by elevating head by 4 cm with respect to isocenter and using a narrow wedge filter was found to approach 50%. When the eye lies outside of the primarily irradiated head region, the dose to eye lens was found to drop to less than 20% of the corresponding dose measured when the eye lens was located in the middle of the x-ray beam. Positioning head phantom off-isocenter by 4 cm and employing a narrow wedge filter results in a moderate reduction of signal-to-noise ratio mainly to the peripheral region of the phantom. Conclusions: Despite typical peak doses to skin, eye lens, brain, and RBM from the standard low-dose brain perfusion 256-slice CT protocol are well below the corresponding thresholds for the induction of erythema, cataract, cerebrovascular disease, and depression of hematopoiesis, respectively, every effort should be made toward optimization of the procedure and minimization of dose received by these tissues. The current study provides evidence that the use of the narrower bowtie filter available may considerably reduce peak absorbed dose to all above radiosensitive tissues with minimal deterioration in image quality. Considerable reduction in peak eye-lens dose may also be achieved by positioning patient head center a few centimeters above isocenter during the exposure.« less

Temporal and spatial features of the formation of DNA adducts in sulfur mustard-exposed skin.

PubMed

Batal, Mohamed; Boudry, Isabelle; Mouret, Stéphane; Wartelle, Julien; Emorine, Sandy; Bertoni, Marine; Bérard, Izabel; Cléry-Barraud, Cécile; Douki, Thierry

2013-12-15

Sulfur mustard (SM) is a chemical warfare agent that targets skin where it induces large blisters. DNA alkylation is a critical step to explain SM-induced cutaneous symptoms. We determined the kinetics of formation of main SM-DNA adducts and compare it with the development of the SM-induced pathogenesis in skin. SKH-1 mice were exposed to 2, 6 and 60 mg/kg of SM and treated skin was biopsied between 6h and 21 days. Formation of SM DNA adducts was dose-dependent with a maximum immediately after exposure. However, adducts were persistent and still detectable 21 days post-exposure. The time-dependent formation of DNA adducts was also found to be correlated with the appearance of apoptotic cells. This temporal correlation suggests that these two early events are responsible for the severity of the damage to the skin. Besides, SM-DNA adducts were also detected in areas located next to contaminated zone, thus suggesting that SM diffuses in skin. Altogether, this work provides for the first time a clear picture of SM-induced genotoxicity using DNA adducts as a marker. © 2013.

Characterization of a cable-free system based on p-type MOSFET detectors for "in vivo" entrance skin dose measurements in interventional radiology.

PubMed

Falco, Maria Daniela; D'Andrea, Marco; Strigari, Lidia; D'Alessio, Daniela; Quagliani, Francesco; Santoni, Riccardo; Bosco, Alessia Lo

2012-08-01

During radiological interventional procedures (RIP) the skin of a patient under examination may undergo a prolonged x-ray exposure, receiving a dose as high as 5 Gy in a single session. This paper describes the use of the OneDose(TM) cable-free system based on p-type MOSFET detectors to determine the entrance skin dose (ESD) at selected points during RIP. At first, some dosimetric characteristics of the detector, such as reproducibility, linearity, and fading, have been investigated using a C-arc as a source of radiation. The reference setting (RS) was: 80 kV energy, 40 cm × 40 cm field of view (FOV), current-time product of 50 mAs and source to skin distance (SSD) of 50 cm. A calibrated PMX III solid state detector was used as the reference detector and Gafchromic(®) films have been used as an independent dosimetric system to test the entire procedure. A calibration factor for the RS and correction factors as functions of tube voltage and FOV size have been determined. Reproducibility ranged from 4% at low doses (around 10 cGy as measured by the reference detector) to about 1% for high doses (around 2 Gy). The system response was found to be linear with respect to both dose measured with the PMX III and tube voltage. The fading test has shown that the maximum deviation from the optimal reading conditions (3 min after a single irradiation) was 9.1% corresponding to four irradiations in one hour read 3 min after the last exposure. The calibration factor in the RS has shown that the system response at the kV energy range is about four times larger than in the MV energy range. A fifth order and fourth order polynomial functions were found to provide correction factors for tube voltage and FOV size, respectively, in measurement settings different than the RS. ESDs measured with the system after applying the proper correction factors agreed within one standard deviation (SD) with the corresponding ESDs measured with the reference detector. The ESDs measured with Gafchromic(®) films were in agreement within one SD compared to the ESDs measured using the OneDose(TM) system, as well. The global uncertainty associated to the OneDose(TM) system established in our experiments, ranged from 7% to 10%, depending on the duration of the RIP due to fading. These values are much lower than the uncertainty commonly accepted for general diagnostic practices (20%) and of about the same size of the uncertainty recommended for practices with high risk of deterministic side effects (7%). The OneDose(TM) system has shown a high sensitivity in the kV energy range and has been found capable of measuring the entrance skin dose in RIP.

Applications of tissue heterogeneity corrections and biologically effective dose volume histograms in assessing the doses for accelerated partial breast irradiation using an electronic brachytherapy source.

PubMed

Shi, Chengyu; Guo, Bingqi; Cheng, Chih-Yao; Eng, Tony; Papanikolaou, Nikos

2010-09-21

A low-energy electronic brachytherapy source (EBS), the model S700 Axxent x-ray device developed by Xoft Inc., has been used in high dose rate (HDR) intracavitary accelerated partial breast irradiation (APBI) as an alternative to an Ir-192 source. The prescription dose and delivery schema of the electronic brachytherapy APBI plan are the same as the Ir-192 plan. However, due to its lower mean energy than the Ir-192 source, an EBS plan has dosimetric and biological features different from an Ir-192 source plan. Current brachytherapy treatment planning methods may have large errors in treatment outcome prediction for an EBS plan. Two main factors contribute to the errors: the dosimetric influence of tissue heterogeneities and the enhancement of relative biological effectiveness (RBE) of electronic brachytherapy. This study quantified the effects of these two factors and revisited the plan quality of electronic brachytherapy APBI. The influence of tissue heterogeneities is studied by a Monte Carlo method and heterogeneous 'virtual patient' phantoms created from CT images and structure contours; the effect of RBE enhancement in the treatment outcome was estimated by biologically effective dose (BED) distribution. Ten electronic brachytherapy APBI cases were studied. The results showed that, for electronic brachytherapy cases, tissue heterogeneities and patient boundary effect decreased dose to the target and skin but increased dose to the bones. On average, the target dose coverage PTV V(100) reduced from 95.0% in water phantoms (planned) to only 66.7% in virtual patient phantoms (actual). The actual maximum dose to the ribs is 3.3 times higher than the planned dose; the actual mean dose to the ipsilateral breast and maximum dose to the skin were reduced by 22% and 17%, respectively. Combining the effect of tissue heterogeneities and RBE enhancement, BED coverage of the target was 89.9% in virtual patient phantoms with RBE enhancement (actual BED) as compared to 95.2% in water phantoms without RBE enhancement (planned BED). About 10% increase in the source output is required to raise BED PTV V(100) to 95%. As a conclusion, the composite effect of dose reduction in the target due to heterogeneities and RBE enhancement results in a net effect of 5.3% target BED coverage loss for electronic brachytherapy. Therefore, it is suggested that about 10% increase in the source output may be necessary to achieve sufficient target coverage higher than 95%.

Applications of tissue heterogeneity corrections and biologically effective dose volume histograms in assessing the doses for accelerated partial breast irradiation using an electronic brachytherapy source

NASA Astrophysics Data System (ADS)

Shi, Chengyu; Guo, Bingqi; Cheng, Chih-Yao; Eng, Tony; Papanikolaou, Nikos

2010-09-01

A low-energy electronic brachytherapy source (EBS), the model S700 Axxent™ x-ray device developed by Xoft Inc., has been used in high dose rate (HDR) intracavitary accelerated partial breast irradiation (APBI) as an alternative to an Ir-192 source. The prescription dose and delivery schema of the electronic brachytherapy APBI plan are the same as the Ir-192 plan. However, due to its lower mean energy than the Ir-192 source, an EBS plan has dosimetric and biological features different from an Ir-192 source plan. Current brachytherapy treatment planning methods may have large errors in treatment outcome prediction for an EBS plan. Two main factors contribute to the errors: the dosimetric influence of tissue heterogeneities and the enhancement of relative biological effectiveness (RBE) of electronic brachytherapy. This study quantified the effects of these two factors and revisited the plan quality of electronic brachytherapy APBI. The influence of tissue heterogeneities is studied by a Monte Carlo method and heterogeneous 'virtual patient' phantoms created from CT images and structure contours; the effect of RBE enhancement in the treatment outcome was estimated by biologically effective dose (BED) distribution. Ten electronic brachytherapy APBI cases were studied. The results showed that, for electronic brachytherapy cases, tissue heterogeneities and patient boundary effect decreased dose to the target and skin but increased dose to the bones. On average, the target dose coverage PTV V100 reduced from 95.0% in water phantoms (planned) to only 66.7% in virtual patient phantoms (actual). The actual maximum dose to the ribs is 3.3 times higher than the planned dose; the actual mean dose to the ipsilateral breast and maximum dose to the skin were reduced by 22% and 17%, respectively. Combining the effect of tissue heterogeneities and RBE enhancement, BED coverage of the target was 89.9% in virtual patient phantoms with RBE enhancement (actual BED) as compared to 95.2% in water phantoms without RBE enhancement (planned BED). About 10% increase in the source output is required to raise BED PTV V100 to 95%. As a conclusion, the composite effect of dose reduction in the target due to heterogeneities and RBE enhancement results in a net effect of 5.3% target BED coverage loss for electronic brachytherapy. Therefore, it is suggested that about 10% increase in the source output may be necessary to achieve sufficient target coverage higher than 95%.

Measurement and comparison of skin dose using OneDose MOSFET and Mobile MOSFET for patients with acute lymphoblastic leukemia

PubMed Central

Mattar, Essam H.; Hammad, Lina F.; Al-Mohammed, Huda I.

2011-01-01

Summary Background Total body irradiation is a protocol used to treat acute lymphoblastic leukemia in patients prior to bone marrow transplant. It is involved in the treatment of the whole body using a large radiation field with extended source-skin distance. Therefore measuring and monitoring the skin dose during the treatment is important. Two kinds of metal oxide semiconductor field effect transistor (OneDose MOSFET and mobile MOSEFT) dosimeter are used during the treatment delivery to measure the skin dose to specific points and compare it with the target prescribed dose. The objective of this study was to compare the variation of skin dose in patients with acute lymphatic leukemia (ALL) treated with total body irradiation (TBI) using OneDose MOSFET detectors and Mobile MOSFET, and then compare both results with the target prescribed dose. Material/Methods The measurements involved 32 patient’s (16 males, 16 females), aged between 14–30 years, with an average age of 22.41 years. One-Dose MOSFET and Mobile MOSFET dosimetry were performed at 10 different anatomical sites on every patient. Results The results showed there was no variation between skin dose measured with OneDose MOSFET and Mobile MOSFET in all patients. Furthermore, the results showed for every anatomical site selected there was no significant difference in the dose delivered using either OneDose MOSFET detector or Mobile MOSFET as compared to the prescribed dose. Conclusions The study concludes that One-Dose MOSFET detectors and Mobile MOSFET both give a direct read-out immediately after the treatment; therefore both detectors are suitable options when measuring skin dose for total body irradiation treatment. PMID:21709641

Measurement and comparison of skin dose using OneDose MOSFET and Mobile MOSFET for patients with acute lymphoblastic leukemia.

PubMed

Mattar, Essam H; Hammad, Lina F; Al-Mohammed, Huda I

2011-07-01

Total body irradiation is a protocol used to treat acute lymphoblastic leukemia in patients prior to bone marrow transplant. It is involved in the treatment of the whole body using a large radiation field with extended source-skin distance. Therefore measuring and monitoring the skin dose during the treatment is important. Two kinds of metal oxide semiconductor field effect transistor (OneDose MOSFET and mobile MOSEFT) dosimeter are used during the treatment delivery to measure the skin dose to specific points and compare it with the target prescribed dose. The objective of this study was to compare the variation of skin dose in patients with acute lymphatic leukemia (ALL) treated with total body irradiation (TBI) using OneDose MOSFET detectors and Mobile MOSFET, and then compare both results with the target prescribed dose. The measurements involved 32 patient's (16 males, 16 females), aged between 14-30 years, with an average age of 22.41 years. One-Dose MOSFET and Mobile MOSFET dosimetry were performed at 10 different anatomical sites on every patient. The results showed there was no variation between skin dose measured with OneDose MOSFET and Mobile MOSFET in all patients. Furthermore, the results showed for every anatomical site selected there was no significant difference in the dose delivered using either OneDose MOSFET detector or Mobile MOSFET as compared to the prescribed dose. The study concludes that One-Dose MOSFET detectors and Mobile MOSFET both give a direct read-out immediately after the treatment; therefore both detectors are suitable options when measuring skin dose for total body irradiation treatment.

The role of gamma irradiation on the extraction of phenolic compounds in onion (Allium cepa L.)

NASA Astrophysics Data System (ADS)

Yang, Eun In; Lee, Eun Mi; Kim, Young Soo; Chung, Byung Yeoup

2012-08-01

The effect of gamma irradiation on the content of total phenolic compounds, especially quercetin (Q), in onion (Allium cepa L.) skin was investigated. Onion skin extracts contained two predominant flavonoid compounds, Q and quercetin-4'-glucoside (Q4'G). After 10 kGy gamma irradiation, the yield of Q in the extracts increased significantly from 36.8 to 153.9 μg/ml of the extract, and the Q4'G content decreased slightly from 165.0 to 134.1 μg/ml. In addition, the total phenolic compound content also increased after irradiation at 10 kGy, from 228.0 μg/g of fresh weight to 346.6 μg/g; negligible changes (237.1-256.7 μg/g) occurred at doses of up to 5 kGy. As we expected, radical-scavenging activity was enhanced remarkably (by 88.8%) in the 10 kGy irradiated sample. A dose-dependent increase in the peak intensity of the electron paramagnetic resonance (EPR) spectra was observed in all irradiated samples, with a maximum increase at 10 kGy. The intensity relative to that of the control was 0.15, and it increased to 1.10 in 10 kGy irradiated samples. The optimum gamma irradiation dose, which is sufficient to break the chemical or physical bonds and release soluble phenols of low molecular weight in onion skin, is about 10 kGy.

[Radiation load on the skin using a silicone-coated polyamide wound dressing during photon and electron radiotherapy].

PubMed

Thilmann, C; Adamietz, I A; Ramm, U; Mose, S; Saran, F; Böttcher, H D

1996-05-01

Silicone-coated polyamide wound dressing is frequently used for the supportive treatment in patients with radiation induced skin lesions. The use of this kind of dressing during radiotherapy with high energy beams shifts the dose built-up effect towards the skin surface. Thus the dose delivered to the skin increases. The present work quantifies changes of the skin dose by a commercial silicon-coated polyamide wound dressing. The dependence on the beam quality and on different treatment techniques is investigated. Measurements were performed with photon (60Co, 6 MV, 42 MV) and electron (7 MeV, 20 MeV, 40 MeV) beams using thin LiF thermoluminescence dosimeters (TLD) in a perspex phantom. The beams were directed perpendicularly to the phantom surface. For 60Co and 6 MV photon beams the skin dose was evaluated in vivo at different beam arrangements and at a given reference dose. For 60Co, 6 MV and 42 MV photon beams wound dressing caused a dose increase on the surface of the perspex phantom by a factor of 1.65, 1.39 and 1.33 respectively. Using oblique or rotational techniques for 60Co and 6 MV photon irradiation the wound dressing increased the skin dose but less compared to perpendicular beam direction. For electron beams the skin dose is relatively high (from 84% to 92%) and an increase by a dressing has no clinical relevance (factor 1.03 to 1.05). The silicone-coated polyamide wound dressing causes no relevant skin dose increase during radiation treatment with electron beams and can be left on the skin during irradiation. During radiation treatment with photon beams like 60Co and 6 MV the protective procedure should be adapted to skin changes, in case of strong skin reactions a removal during the time of irradiation should be considered.

The thermoregulatory effects of noradrenaline, serotonin and carbachol injected into the rat spinal subarachnoid space.

PubMed

Lopachin, R M; Rudy, T A

1982-12-01

1. We have examined the effects on thermoregulation in the rat of noradrenaline bitartrate (NA), 5-hydroxytryptamine hydrochloride (5-HT) and carbamylcholine chloride (CCh) injected into the lumbar spinal subarachnoid space via a chronic indwelling catheter.2. Intrathecal injections of the monoamines and CCh reproducibly affected thermoregulation, whereas injections of control solutions had no effect.3. Intrathecal injections of NA (0.01-0.30 mumol) produced a dose-dependent hypothermia associated with a decrease in tail skin vasomotor tone. Shivering activity was not depressed during the hypothermia and sometimes increased. Intrathecal administration of the alpha-adrenergic agonist clonidine (0.0175-0.070 mumol) elicited changes in T(c) and T(sk) similar to those induced by intrathecal NA.4. Intrathecal 5-HT (0.030-0.90 mumol) elicited a dose-dependent hyperthermia accompanied by increased tail skin vasomotor tone and increased shivering.5. CCh injected intrathecally (0.001-0.06 mumol) evoked a dose-dependent hyperthermia. During the period when core temperature was rising, tail skin vasomotor tone increased and shivering-like activity was present. Once the maximum core temperature had been reached, tail skin vasodilatation occurred. Vasodilatation persisted until core temperature had returned to normal.6. Intravenous injections of 5-HT (0.30 and 0.90 mumol) or CCh (0.006 and 0.03 mumol) caused no thermoregulatory effect. The effects of these agents injected intrathecally were therefore not due to an action in the periphery.7. Intravenous infusions of NA (0.06 and 0.10 mumol) produced hypothermia and transient tail skin vasodilatation. We suggest that an action at peripheral sites may have contributed to the effects produced by intrathecal injection of this monamine.8. These findings suggest that spinal noradrenergic, serotonergic and cholinergic synapses may be importantly involved in the control of body temperature in the rat. The possible functional roles of these synapses and the putative spinal sites of action of the injected substances are discussed.

SU-G-JeP2-09: Minimal Skin Dose Increase in Longitudinal Rotating Biplanar Linac-MR Systems: Examination of Radiation Energy and Flattening Filter Design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fallone, B; Keyvanloo, A; Burke, B

Purpose: To quantify increase in entrance skin-dose due to magnetic fields of the Alberta longitudinal linac-MR by examining the effect of radiation energy and flattening filter, using Monte Carlo calculations and accurate 3-D models of the magnetic field. Methods: The 3-D magnetic fields generated by the bi-planar Linac-MR are calculated with FEM using Opera-3D. BEAMnrc simulates the particle phase-space in the presence of the rapidly decaying fringe field of 0.5T MRI assembled with a Varian 600C linac with an isocentre distance of 130 cm for 6 MV and 10 MV beams. Skin doses are calculated at an average depth ofmore » 70 µm using DOSXYZnrc with varying SSDs and field sizes. Furthermore, flattening filters are reshaped to compensate for the significant drop in dose rate due to increased SAD of 130 cm and skin-doses are evaluated. Results: The confinement effect of the MRI fringe field on the contaminant electrons is minimal. For SSDs of 100 – 120 cm the increase in skin dose is ∼6% – 19% and ∼1% – 9% for the 6 and 10 MV beams, respectively. For 6MV, skin dose increases from ∼10.5% to 1.5%. for field-size increases of 5×5 cm2 to 20×20 cm2. For 10 MV, skin dose increases by ∼6% for a 5×5 cm2 field, and decreases by ∼1.5% for a 20×20 cm2 field. The reshaped flattening filter increases the dose rate from 355 MU/min to 529 MU/min (6 MV) or 604 MU/min (10 MV), while the skin-dose increases by only an additional ∼2.6% (all percent increases in skin dose are relative to Dmax). Conclusion: There is minimal increase in the entrance skin dose and minimal/no decrease in the dose rate of the Alberta longitudinal linac-MR system. There is even lower skin-dose increase at 10 MV. Funding: Alberta Innovates - Health Solutions (AIHS) Conflict of Interest: Fallone is a co-founder and CEO of MagnetTx Oncology Solutions (under discussions to license Alberta bi-planar linac MR for commercialization)« less

The Effects of Erzincan Grape (Vitis vinifera spp., Cimin) and Benzothiazol on a Caenorhabditis elegans Organism Model

PubMed Central

Ozpinar, Hulya; Ozpinar, Necati; Karakus, Savas

2017-01-01

Background: Grapes and their products are known to have been used for the treatment of diseases throughout history. Objective: It was aimed to investigate the effects of Erzincan Cimin grapes on an organism model of Caenorhabditis elegans N2 wild type and C. elegans BS913 strains with gonad cancer. Materials and Methods: The effects of methanol extracts of the skin and seeds of Erzincan Cimin grapes were examined separately on C. elegans N2 wild type and an effect was determined on lifespan. By applying GS-MS analysis, a potential agent substance was determined in the skin and seed methanol extracts. This substance was purchased and the effects of this substance were investigated on lifespan and fertility in C. elegans BS913 strains with gonad cancer. In addition, the effects on young subjects exposed to this agent substance in L1 form were investigated. Results: Grape seed and skin methanol extract was observed to prolong the lifespan most at a dose of 10 mg/100 mL. Lifespan was determined to be at a maximum in a gonad cancer organism model with benzothiazol at a dose of 50 ppm. At the same dose, positive effects were determined on the fertility of strains with cancer. When the effects of benzothiazol were examined on young L1 forms, an evident retardation of growth was determined at doses of 10, 50, and 100 ppm. Conclusion: Owing to anti-carcinogenic effects of benzothiazol and benzothiazol-derived substances, they can be considered as agent substances in academic studies related to cancer. SUMMARY The effects of methanol extracts of the skin and seeds of Erzincan Cimin grapes were examined on C. elegans N2 wild type and an effect was determined on lifespanThrough GS-MS analysis, benzothiazol was determined in the skin methanol extractsBenzothiazol was purchased and the effects of this substance were investigated on lifespan and fertility in C. elegans BS913 strains with gonad cancerThe effects on young subjects exposed to benzothiazol in L1 formGrape seed, skin methanol extract, and benzothiazol was observed to prolong the lifespanPositive effects were determined on the fertility of gonad cancer strains. Abbreviations used: GC-MS: gas chromatography and mass spectrometry; C. elegans: Caenorhabditis elegans; NGM: Nematode growth medium; E. coli: Escherichia coli; FUDR: Fluorodeoxyuridine; LDL: Low-density lipoprotein. PMID:28808410

The Effects of Erzincan Grape (Vitis vinifera spp., Cimin) and Benzothiazol on a Caenorhabditis elegans Organism Model.

PubMed

Ozpinar, Hulya; Ozpinar, Necati; Karakus, Savas

2017-07-01

Grapes and their products are known to have been used for the treatment of diseases throughout history. It was aimed to investigate the effects of Erzincan Cimin grapes on an organism model of Caenorhabditis elegans N2 wild type and C. elegans BS913 strains with gonad cancer. The effects of methanol extracts of the skin and seeds of Erzincan Cimin grapes were examined separately on C. elegans N2 wild type and an effect was determined on lifespan. By applying GS-MS analysis, a potential agent substance was determined in the skin and seed methanol extracts. This substance was purchased and the effects of this substance were investigated on lifespan and fertility in C. elegans BS913 strains with gonad cancer. In addition, the effects on young subjects exposed to this agent substance in L1 form were investigated. Grape seed and skin methanol extract was observed to prolong the lifespan most at a dose of 10 mg/100 mL. Lifespan was determined to be at a maximum in a gonad cancer organism model with benzothiazol at a dose of 50 ppm. At the same dose, positive effects were determined on the fertility of strains with cancer. When the effects of benzothiazol were examined on young L1 forms, an evident retardation of growth was determined at doses of 10, 50, and 100 ppm. Owing to anti-carcinogenic effects of benzothiazol and benzothiazol-derived substances, they can be considered as agent substances in academic studies related to cancer. The effects of methanol extracts of the skin and seeds of Erzincan Cimin grapes were examined on C. elegans N2 wild type and an effect was determined on lifespanThrough GS-MS analysis, benzothiazol was determined in the skin methanol extractsBenzothiazol was purchased and the effects of this substance were investigated on lifespan and fertility in C. elegans BS913 strains with gonad cancerThe effects on young subjects exposed to benzothiazol in L1 formGrape seed, skin methanol extract, and benzothiazol was observed to prolong the lifespanPositive effects were determined on the fertility of gonad cancer strains. Abbreviations used: GC-MS: gas chromatography and mass spectrometry; C. elegans : Caenorhabditis elegans ; NGM: Nematode growth medium; E. coli : Escherichia coli ; FUDR: Fluorodeoxyuridine; LDL: Low-density lipoprotein.

Evaluation of contralateral breast skin doses by thermoluminescent dosimeters of patients receiving adjuvant radiotherapy for breast cancer.

PubMed

Gorken, I B; Kentli, S; Alanyali, H; Karagüler, Z; Kinay, M

2002-01-01

It is reported that low dose radiation received by the contralateral breast (CLB) during adjuvant radiotherapy (RT) is carcinogenic. This trial was planned to evaluate the CLB skin doses received during adjuvant RT of breast carcinoma. Twenty-four breast carcinoma patients treated locally or locoregionally with adjuvant RT were included. RT was performed with only tangential fields (TA) in 6 patients whereas 9 patients had an extra internal mammary (IM) field (TAIM). The remaining 9 patients received 5-field locoregional RT (5FLR). All patients were treated with wedge filters except for 3 TA patients. Of 9 5FLR patients IM fields were treated with Co60 in 5 and with electrons in the remaining 4 patients. LiF(2)-based Ribbon type thermoluminescent dosimeters (TLD) were used for dose evaluation. An average of 10 TLD's, placed with 1 cm gaps beginning from the medial border of the treatment field along the central axis were used to obtain dose measurements. Median measure of TLD's between 2-8 cm and maximum dose point (MDP) values in the same range were used to evaluate the CLB dose. In TA patients the CLB skin received 6.3% of the total dose in patients treated with wedge filters and 7.13% with half-beam blocks. For 6 TAIM patients with IM fields treated with Co60, the CLB dose was 7.24%. In 5 of 9 5FLR patients, whose IM fields were treated with Co60 the CLB skin received 8.8% of the total dose, while for electron beam therapy the CLB dose was 5.44%. CLB median MDP values were as follows: 12.76% in TA patients treated with wedge filters and 11.45% with half-beam blocking; 11.89% in TAIM patients with IM fields treated with Co60 and 7.83% with electron beams; 12.29% in 5FLR patients of whose IM fields were treated with Co60 and 8.94% with electron beams. When compared to wedge filters, halfbeam blocks caused 13% increase in CLB doses. If IM fields were added, 27.5% and 62% increases at CLB doses were established with Co60 when compared to electron beam RT in 3-field and 5-field treatments, respectively. CLB doses increased by 15-40% with the increased number of treatment fields. MDP values were also found to be higher with IM fields treated with Co60, but the number of treatment fields and accessories used seemed to have no effect on MDP doses. We conclude that by using wedge filters instead of half-beam blocks and by increasing the number of fractions treated with electron energies for IM fields, apparent decreases in CLB doses can be obtained. Large number of cases is needed to statistically establish the significant differences between subgroups.

In vitro permeation and disposition of niacinamide in silicone and porcine skin of skin barrier-mimetic formulations.

PubMed

Haque, Tasnuva; Lane, Majella E; Sil, Bruno C; Crowther, Jonathan M; Moore, David J

2017-03-30

Niacinamide (NIA) is an amide form of vitamin B3 which is used in cosmetic formulations to improve various skin conditions and it has also been shown to increase stratum corneum thickness following repeated application. In this study, three doses (5, 20 and 50μL per cm 2 ) of two NIA containing oil-in-water skin barrier-mimetic formulations were evaluated in silicone membrane and porcine ear skin and compared with a commercial control formulation. Permeation studies were conducted over 24h in Franz cells and at the end of the experiment membranes were washed and niacinamide was extracted. For the three doses, retention or deposition of NIA was generally higher in porcine skin compared with silicone membrane, consistent with the hydrophilic nature of the active. Despite the control containing a higher amount of active, comparable amounts of NIA were deposited in skin for all formulations for all doses; total skin absorption values (permeation and retention) of NIA were also comparable across all formulations. For infinite (50μL) and finite (5μL) doses the absolute permeation of NIA from the control formulation was significantly higher in porcine skin compared with both test formulations. This likely reflects differences in formulation components and/or presence of skin penetration enhancers in the formulations. Higher permeation for the 50 and 20μL dose was also evident in porcine skin compared with silicone membrane but the opposite is the case for the finite dose. The findings point to the critical importance of dose and occlusion when evaluating topical formulations in vitro and also the likelihood of exaggerated effects of excipients on permeation at infinite and pseudo-finite dose applications. Copyright © 2017 Elsevier B.V. All rights reserved.

SU-E-T-459: Impact of Source Position and Traveling Time On HDR Skin Surface Applicator Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jeong, J; Barker, C; Zaider, M

Purpose: Observed dosimetric discrepancy between measured and treatment planning system (TPS) predicted values, during applicator commissioning, were traced to source position uncertainty in the applicator. We quantify the dosimetric impact of this geometric uncertainty, and of the source traveling time inside the applicator, and propose corrections for clinical use. Methods: We measured the dose profiles from the Varian Leipzig-style (horizontal) HDR skin applicator, using EBT3 film, photon diode, and optically stimulated luminescence dosimeter (OSLD) and three different GammaMed HDR afterloders. The dose profiles and depth dose of each aperture were measured at several depths (up to about 10 mm, dependingmore » on the dosimeter). The measured dose profiles were compared with Acuros calculated profiles in BrachyVision TPS. For the impact of the source position, EBT3 film measurements were performed with applicator, facing-down and facing-up orientations. The dose with and without source traveling was measured with diode detector using HDR timer and electrometer timer, respectively. Results: Depth doses measured using the three dosimeters were in good agreement, but were consistently higher than the Acuros dose calculations. Measurements with the applicator facing-up were significantly lower than those in the facing-down position with maximum difference of about 18% at the surface, due to source sag inside the applicator. Based on the inverse-square law, the effective source sag was evaluated to be about 0.5 mm from the planned position. The additional dose from the source traveling was about 2.8% for 30 seconds with 10 Ci source, decreasing with increased dwelling time and decreased source activity. Conclusion: Due to the short source-to-surface distance of the applicator, the small source sag inside the applicator has significant dosimetric impact, which should be considered before the clinical use of the applicator. Investigation of the effect for other applicators that have relatively large source lumen inner diameter may be warranted. Christopher Barker and Gil’ad Cohen are receiving research support for a study of skin surface brachytherapy from Elekta.« less

Evaluating the consistency of location of the most severe acute skin reaction and highest skin dose measured by thermoluminescent dosimeter during radiotherapy for breast cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Li-Min, E-mail: limin.sun@yahoo.com; Huang, Chih-Jen; Department of Faculty of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan

We conducted this prospective study to evaluate whether the location of the most severe acute skin reaction matches the highest skin dose measured by thermoluminescent dosimeter (TLD) during adjuvant radiotherapy (RT) for patients with breast cancer after breast conservative surgery. To determine whether TLD measurement can reflect the location of the most severe acute skin reaction, 80 consecutive patients were enrolled in this prospective study. We divided the irradiated field into breast, axillary, inframammary fold, and areola/nipple areas. In 1 treatment session when obvious skin reaction occurred, we placed the TLD chips onto the 4 areas and measured the skinmore » dose. We determined whether the highest measured skin dose area is consistent with the location of the most severe skin reaction. The McNemar test revealed that the clinical skin reaction and TLD measurement are more consistent when the most severe skin reaction occurred at the axillary area, and the p = 0.0108. On the contrary, TLD measurement of skin dose is less likely consistent with clinical observation when the most severe skin reaction occurred at the inframammary fold, breast, and areola/nipple areas (all the p > 0.05). Considering the common site of severe skin reaction over the axillary area, TLD measurement may be an appropriate way to predict skin reaction during RT.« less

Considerations for applying VARSKIN mod 2 to skin dose calculations averaged over 10 cm2.

PubMed

Durham, James S

2004-02-01

VARSKIN Mod 2 is a DOS-based computer program that calculates the dose to skin from beta and gamma contamination either directly on skin or on material in contact with skin. The default area for calculating the dose is 1 cm2. Recently, the U.S. Nuclear Regulatory Commission issued new guidelines for calculating shallow dose equivalent from skin contamination that requires the dose be averaged over 10 cm2. VARSKIN Mod 2 was not filly designed to calculate beta or gamma dose estimates averaged over 10 cm2, even though the program allows the user to calculate doses averaged over 10 cm2. This article explains why VARSKIN Mod 2 overestimates the beta dose when applied to 10 cm2 areas, describes a manual method for correcting the overestimate, and explains how to perform reasonable gamma dose calculations averaged over 10 cm2. The article also describes upgrades underway in Varskin 3.

Effect of application site, clothing barrier, and application site washing on testosterone transfer with a 1.62% testosterone gel.

PubMed

Stahlman, Jodi; Britto, Margaret; Fitzpatrick, Sherahe; McWhirter, Cecilia; Testino, Samuel A; Brennan, John J; Zumbrunnen, Troy L

2012-02-01

To evaluate the effect of application site location, clothing barrier, and application site washing on testosterone transfer from males dosed with 1.62% testosterone gel to female partners. Open-label, randomized, parallel group, crossover study performed in 24 healthy male/female couples. 2.5 or 5.0 g of gel was applied to upper arms and shoulders or abdomens of male subjects. Skin contact occurred 2 hours after gel application between male and female subjects to compare the effect of wearing or not wearing a t-shirt, washing or not washing before contact, and the effect of differing application sites. Treatments were separated by a 1-week washout period. On each dosing day, 15 minutes of supervised skin contact occurred between the dosed male and female partner. Contact was either abdomen to abdomen (male to female), or upper arms/shoulders (male) to upper arms/shoulders, wrists and hands (female), depending on the male application site. Serum samples were collected from females at baseline and after contact to assess secondary testosterone exposure. C(max) (maximum serum concentration), AUC(0-24) (area under serum concentration-time curve from 0-24 hours), and C(av) (time-averaged concentration over 24-hour post-contact period) were assessed. Subjects were monitored for adverse events. Testosterone exposure (C(av) and C(max)) in females increased by up to 27% (2.5 g) or up to 280% (5.0 g) from baseline after direct skin contact at 2 hours after gel application, although C(av) remained within the female eugonadal range. Transfer from the abdomen was prevented when a t-shirt was worn (2.5-g dose). When the application site was washed before contact, mean C(av) was comparable to baseline, and C(max) was slightly higher (14%). Transfer was higher after direct skin-to-skin contact when the application and contact sites were upper arms/shoulders versus the abdomen. Testosterone concentrations returned to baseline within 48 hours after last skin contact. There is a risk of testosterone transfer from males using 1.62% testosterone gel to others who come into direct skin contact with the application site. This can be prevented by covering the application site with a t-shirt (2.5-g dose), or washing the application site before contact. Women for these studies were not selected by menopausal status. The study was conducted under circumstances that were intended to simulate exaggerated conditions of contact and may not represent average contact under normal conditions. CLINICAL TRIAL REGISTRATION NCT NUMBERS: Study was not registered (first subject enrolled 28 November 2007).

An assessment of the use of skin flashes in helical tomotherapy using phantom and in-vivo dosimetry.

PubMed

Tournel, Koen; Verellen, Dirk; Duchateau, Michael; Fierens, Yves; Linthout, Nadine; Reynders, Truus; Voordeckers, Mia; Storme, Guy

2007-07-01

In helical tomotherapy the nature of the optimizing and planning systems allows the delivery of dose on the skin using a build-up compensating technique (skin flash). However, positioning errors or changes in the patient's contour can influence the correct dosage in these regions. This work studies the behavior of skin-flash regions using phantom and in-vivo dosimetry. The dosimetric accuracy of the tomotherapy planning system in skin-flash regions is checked using film and TLD on phantom. Positioning errors are induced and the effect on the skin dose is investigated. Further a volume decrease is simulated using bolus material and the results are compared. Results show that the tomotherapy planning system calculates dose on skin regions within 2 SD using TLD measurements. Film measurements show drops of dose of 2.8% and 26% for, respectively, a 5mm and 10mm mispositioning of the phantom towards air and a dose increase of 9% for a 5mm shift towards tissue. These measurements are confirmed by TLD measurements. A simulated volume reduction shows a similar behavior with a 2.6% and 19.4% drop in dose, measured with TLDs. The tomotherapy system allows adequate planning and delivery of dose using skin flashes. However, exact positioning is crucial to deliver the dose at the exact location.

Systemic Delivery of Atropine Sulfate by the MicroDose Dry-Powder Inhaler

PubMed Central

Venkataramanan, R.; Hoffman, R.M.; George, M.P.; Petrov, A.; Richards, T.; Zhang, S.; Choi, J.; Gao, Y.Y.; Oakum, C.D.; Cook, R.O.; Donahoe, M.

2013-01-01

Abstract Background Inhaled atropine is being developed as a systemic and pulmonary treatment for the extended recovery period after chemical weapons exposure. We performed a pharmacokinetics study comparing inhaled atropine delivery using the MicroDose Therapeutx Dry Powder Inhaler (DPIA) with intramuscular (IM) atropine delivery via auto-injector (AUTO). Methods The MicroDose DPIA utilizes a novel piezoelectric system to aerosolize drug and excipient from a foil dosing blister. Subjects inhaled a 1.95-mg atropine sulfate dose from the dry powder inhaler on one study day [5 doses×0.4 mg per dose (nominal) delivered over 12 min] and received a 2-mg IM injection via the AtroPen® auto-injector on another. Pharmacokinetics, pharmacodynamic response, and safety were studied for 12 hr. Results A total of 17 subjects were enrolled. All subjects completed IM dosing. One subject did not perform inhaled delivery due to a skin reaction from the IM dose. Pharmacokinetic results were as follows: area under the curve concentration, DPIA=20.1±5.8, AUTO=23.7±4.9 ng hr/mL (means±SD); maximum concentration reached, DPIA=7.7±3.5, AUTO=11.0±3.8 ng/mL; time to reach maximum concentration, DPIA=0.25±0.47, AUTO=0.19±0.23 hr. Pharmacodynamic results were as follows: maximum increase in heart rate, DPIA=18±12, AUTO=23±13 beats/min; average change in 1-sec forced expiratory volume at 30 min, DPIA=0.16±0.22 L, AUTO=0.11±0.29 L. The relative bioavailability for DPIA was 87% (based on output dose). Two subjects demonstrated allergic responses: one to the first dose (AUTO), which was mild and transient, and one to the second dose (DPIA), which was moderate in severity, required treatment with oral and intravenous (IV) diphenhydramine and IV steroids, and lasted more than 7 days. Conclusions Dry powder inhalation is a highly bioavailable route for attaining rapid and consistent systemic concentrations of atropine. PMID:22691110

Systemic delivery of atropine sulfate by the MicroDose Dry-Powder Inhaler.

PubMed

Corcoran, T E; Venkataramanan, R; Hoffman, R M; George, M P; Petrov, A; Richards, T; Zhang, S; Choi, J; Gao, Y Y; Oakum, C D; Cook, R O; Donahoe, M

2013-02-01

Inhaled atropine is being developed as a systemic and pulmonary treatment for the extended recovery period after chemical weapons exposure. We performed a pharmacokinetics study comparing inhaled atropine delivery using the MicroDose Therapeutx Dry Powder Inhaler (DPIA) with intramuscular (IM) atropine delivery via auto-injector (AUTO). The MicroDose DPIA utilizes a novel piezoelectric system to aerosolize drug and excipient from a foil dosing blister. Subjects inhaled a 1.95-mg atropine sulfate dose from the dry powder inhaler on one study day [5 doses × 0.4 mg per dose (nominal) delivered over 12 min] and received a 2-mg IM injection via the AtroPen® auto-injector on another. Pharmacokinetics, pharmacodynamic response, and safety were studied for 12 hr. A total of 17 subjects were enrolled. All subjects completed IM dosing. One subject did not perform inhaled delivery due to a skin reaction from the IM dose. Pharmacokinetic results were as follows: area under the curve concentration, DPIA=20.1±5.8, AUTO=23.7±4.9 ng hr/mL (means±SD); maximum concentration reached, DPIA=7.7±3.5, AUTO=11.0±3.8 ng/mL; time to reach maximum concentration, DPIA=0.25±0.47, AUTO=0.19±0.23 hr. Pharmacodynamic results were as follows: maximum increase in heart rate, DPIA=18±12, AUTO=23±13 beats/min; average change in 1-sec forced expiratory volume at 30 min, DPIA=0.16±0.22 L, AUTO=0.11±0.29 L. The relative bioavailability for DPIA was 87% (based on output dose). Two subjects demonstrated allergic responses: one to the first dose (AUTO), which was mild and transient, and one to the second dose (DPIA), which was moderate in severity, required treatment with oral and intravenous (IV) diphenhydramine and IV steroids, and lasted more than 7 days. Dry powder inhalation is a highly bioavailable route for attaining rapid and consistent systemic concentrations of atropine.

SU-F-J-87: Impact Of The Dosimetric Consequences From Minimal Displacements Throughout The Treatment Time In APBI With SAVI Applicators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chandrasekara, S; Pella, S; Hyvarinen, M

2016-06-15

Purpose: To assess the variation in dose received by the organs at risk (OARs) due to inter-fractional motion by SAVI to determine the importance of providing proper immobilization Methods: An analysis of 15 patients treated with SAVI applicators were considered for this study. Treatment planning teams did not see significant changes in their CT scans through scout images and initial treatment plan was used for the entire treatment. These scans, taken before each treatment were imported in to the treatment planning system and were fused together with respective to the applicator, using landmark registration. Dosimetric evaluations were performed. Dose receivedmore » by skin, ribs and PTV(Planning target volume) respect to the initial treatment plan were measured. Results: Contours of the OARs were not similar with the initial image. Deduction in volumes of PTV and cavity, small deviations in displacements from the applicator to the OARs, difference in doses received by the OARs between treatments were noticed. The maximum, minimum, average doses varied between 10% to 20% 5% to 8% and 15% to 20% in ribs and skin. The 0.1cc doses to OARs showed an average change of 10% of the prescribed dose. PTV was receiving a different dose than the estimated dose Conclusion: The variation in volumes and isodoses related to the OARs, PTV receiving a lesser dose than the prescribed dose indicate that the estimated doses are different from the received dose. This study reveals the urgent need of improving the immobilization methods. Taking a CT scan before each treatment and replanning is helpful to minimize the risk of delivering undesired high doses to the OARs. Patient positioning, motion, respiration, observer differences and time lap between the planning and treating can arise more complications. VacLock, Positioning cushions, Image guided brachytherapy and adjustable registration should be used for further improvements.« less

Evaluating the consistency of location of the most severe acute skin reaction and highest skin dose measured by thermoluminescent dosimeter during radiotherapy for breast cancer.

PubMed

Sun, Li-Min; Huang, Chih-Jen; Chen, Hsiao-Yun; Chang, Gia-Hsin; Tsao, Min-Jen

2016-01-01

We conducted this prospective study to evaluate whether the location of the most severe acute skin reaction matches the highest skin dose measured by thermoluminescent dosimeter (TLD) during adjuvant radiotherapy (RT) for patients with breast cancer after breast conservative surgery. To determine whether TLD measurement can reflect the location of the most severe acute skin reaction, 80 consecutive patients were enrolled in this prospective study. We divided the irradiated field into breast, axillary, inframammary fold, and areola/nipple areas. In 1 treatment session when obvious skin reaction occurred, we placed the TLD chips onto the 4 areas and measured the skin dose. We determined whether the highest measured skin dose area is consistent with the location of the most severe skin reaction. The McNemar test revealed that the clinical skin reaction and TLD measurement are more consistent when the most severe skin reaction occurred at the axillary area, and the p = 0.0108. On the contrary, TLD measurement of skin dose is less likely consistent with clinical observation when the most severe skin reaction occurred at the inframammary fold, breast, and areola/nipple areas (all the p > 0.05). Considering the common site of severe skin reaction over the axillary area, TLD measurement may be an appropriate way to predict skin reaction during RT. Copyright © 2016 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Peak skin and eye lens radiation dose from brain perfusion CT based on Monte Carlo simulation.

PubMed

Zhang, Di; Cagnon, Chris H; Villablanca, J Pablo; McCollough, Cynthia H; Cody, Dianna D; Stevens, Donna M; Zankl, Maria; Demarco, John J; Turner, Adam C; Khatonabadi, Maryam; McNitt-Gray, Michael F

2012-02-01

The purpose of our study was to accurately estimate the radiation dose to skin and the eye lens from clinical CT brain perfusion studies, investigate how well scanner output (expressed as volume CT dose index [CTDI(vol)]) matches these estimated doses, and investigate the efficacy of eye lens dose reduction techniques. Peak skin dose and eye lens dose were estimated using Monte Carlo simulation methods on a voxelized patient model and 64-MDCT scanners from four major manufacturers. A range of clinical protocols was evaluated. CTDI(vol) for each scanner was obtained from the scanner console. Dose reduction to the eye lens was evaluated for various gantry tilt angles as well as scan locations. Peak skin dose and eye lens dose ranged from 81 mGy to 348 mGy, depending on the scanner and protocol used. Peak skin dose and eye lens dose were observed to be 66-79% and 59-63%, respectively, of the CTDI(vol) values reported by the scanners. The eye lens dose was significantly reduced when the eye lenses were not directly irradiated. CTDI(vol) should not be interpreted as patient dose; this study has shown it to overestimate dose to the skin or eye lens. These results may be used to provide more accurate estimates of actual dose to ensure that protocols are operated safely below thresholds. Tilting the gantry or moving the scanning region further away from the eyes are effective for reducing lens dose in clinical practice. These actions should be considered when they are consistent with the clinical task and patient anatomy.

A system to track skin dose for neuro-interventional cone-beam computed tomography (CBCT)

NASA Astrophysics Data System (ADS)

Vijayan, Sarath; Xiong, Zhenyu; Rudin, Stephen; Bednarek, Daniel R.

2016-03-01

The skin-dose tracking system (DTS) provides a color-coded illustration of the cumulative skin-dose distribution on a closely-matching 3D graphic of the patient during fluoroscopic interventions in real-time for immediate feedback to the interventionist. The skin-dose tracking utility of DTS has been extended to include cone-beam computed tomography (CBCT) of neurointerventions. While the DTS was developed to track the entrance skin dose including backscatter, a significant part of the dose in CBCT is contributed by exit primary radiation and scatter due to the many overlapping projections during the rotational scan. The variation of backscatter inside and outside the collimated beam was measured with radiochromic film and a curve was fit to obtain a scatter spread function that could be applied in the DTS. Likewise, the exit dose distribution was measured with radiochromic film for a single projection and a correction factor was determined as a function of path length through the head. Both of these sources of skin dose are added for every projection in the CBCT scan to obtain a total dose mapping over the patient graphic. Results show the backscatter to follow a sigmoidal falloff near the edge of the beam, extending outside the beam as far as 8 cm. The exit dose measured for a cylindrical CTDI phantom was nearly 10 % of the entrance peak skin dose for the central ray. The dose mapping performed by the DTS for a CBCT scan was compared to that measured with radiochromic film and a CTDI-head phantom with good agreement.

Association of malignancy with rapid growth in early lesions induced by irradiation of rat skin

DOE Office of Scientific and Technical Information (OSTI.GOV)

McGregor, J.F.

1979-04-01

Epithelial lesions induced by irradiation of rat skin were studied to determine (a) the relationship of malignancy to dose, (b) the types of lesions and circumstances leading to overt malignancy, and (c) the growth rates of lesions progressing to malignancy versus those of lesions remaining benign. High doses of radiation were shown to be associated with the production of epidermal cancers, the maximum yield being obtained at 6,400 rads. Conversely, a peak yield of noncancerous lesions was obtained at 1,600 rads. This association between malignancy and high dose was consistent for cancers evolving from warts, cysts, and chronic ulcers. Althoughmore » the proportion of warts among the induced lesions was much higher than that of the cysts or chronic ulcers (76, 14, and 10%, respectively), the likelihood of warts becoming cancerous was substantially lower (14, 23, and 21%). The combined data for all doses showed that the latency period of the epidermal cancers was significantly (P = 0.015) shorter than that of the benign tumors. Rapid growth rates were observed for warts, cysts, and chronic ulcers progressing to overt cancer, and these did not overlap at any point on the growth scale with rates for benign tumors. This finding suggested that the potential for malignant development had been established early in the carcinogenic process, very likely at induction.« less

Single subcutaneous dosing of cefovecin in rhesus monkeys (Macaca mulatta): a pharmacokinetic study.

PubMed

Bakker, J; Thuesen, L R; Braskamp, G; Skaanild, M T; Ouwerling, B; Langermans, J A M; Bertelsen, M F

2011-10-01

Cefovecin is a third-generation cephalosporin approved for antibacterial treatment with a 14-day dosing interval in dogs and cats. This antibiotic may also be useful for zoo and wildlife veterinary medicine, because of its broad spectrum and long duration of activity. The aim of the study was to determine whether cefovecin is a suitable antibiotic to prevent skin wound infection in rhesus monkeys. Therefore, the pharmacokinetics (PK) of cefovecin after a single subcutaneous injection at 8 mg/kg bodyweight in four rhesus monkeys (Macaca mulatta) and sensitivity of bacterial isolates from fresh skin wounds were determined. After administration, blood, urine, and feces were collected, and concentrations of cefovecin were determined. Further, the minimum inhibitory concentrations (MIC) for bacteria isolated from fresh skin wounds of monkeys during a health control program were determined. The mean maximum plasma concentration (C(max) ) of cefovecin was 78 μg/mL and was achieved after 57 min. The mean apparent long elimination half-life (t½) was 6.6 h and excretion occurred mainly via urine. The MIC for the majority of the bacteria examined was >100 μg/mL. The PK of cefovecin in rhesus monkeys is substantially different than for dogs and cats. Cefovecin rapidly reached C(max) which however was lower than most of the MIC levels and with a very short t½. Therefore, cefovecin is not recommended for treating skin wounds in rhesus monkeys. © 2011 Blackwell Publishing Ltd.

Skin dose from radionuclide contamination on clothing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taylor, D.C.; Hussein, E.M.A.; Yuen, P.S.

1997-06-01

Skin dose due to radio nuclide contamination on clothing is calculated by Monte Carlo simulation of electron and photon radiation transport. Contamination due to a hot particle on some selected clothing geometries of cotton garment is simulated. The effect of backscattering in the surrounding air is taken into account. For each combination of source-clothing geometry, the dose distribution function in the skin, including the dose at tissue depths of 7 mg cm{sup -2} and 1,000 Mg cm{sup -2}, is calculated by simulating monoenergetic photon and electron sources. Skin dose due to contamination by a radionuclide is then determined by propermore » weighting of & monoenergetic dose distribution functions. The results are compared with the VARSKIN point-kernel code for some radionuclides, indicating that the latter code tends to under-estimate the dose for gamma and high energy beta sources while it overestimates skin dose for low energy beta sources. 13 refs., 4 figs., 2 tabs.« less

Effects of immobilization mask material on surface dose

PubMed Central

Hadley, Scott W.; Kelly, Robin; Lam, Kwok

2005-01-01

This work investigates the increase in surface dose caused by thermoplastic masks used for patient positioning and immobilization. A thermoplastic mask is custom fit by stretching a heated mask over the patient at the time of treatment simulation. This mask is then used at treatment to increase the reproducibility of the patient position. The skin sparing effect of mega‐voltage X‐ray beams can be reduced when the patient's skin surface is under the mask material. The sheet of thermoplastic mask has holes to reduce this effect and is available from one manufacturer with two different sizes of holes, one larger than the other. This work investigates the increase in surface dose caused by the mask material and quantifies the difference between the two samples of masks available. The change in the dose buildup was measured using an Attix parallel plate chamber by measuring tissue maximum ratios (TMRs) using solid water. Measurements were made with and without the mask material on the surface of the solid water for 6‐MV and 15‐MV X‐ray beams. The effective thickness of equivalent water was estimated from the TMR curves, and the increase in surface dose was estimated. The buildup effect was measured to be equivalent to 2.2 mm to 0.6 mm for masks that have been stretched by different amounts. The surface dose was estimated to change from 16% and 12% for 6 MV and 15 MV, respectively, to 27% to 61% for 6 MV and 18% to 40% for 15 MV with the mask samples. PACS number: 87.53.Dq PMID:15770192

SU-E-T-118: Dose Verification for Accuboost Applicators Using TLD, Ion Chamber and Gafchromic Film Measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chisela, W; Yao, R; Dorbu, G

Purpose: To verify dose delivered with HDR Accuboost applicators using TLD, ion chamber and Gafchromic film measurements and to examine applicator leakage. Methods: A microSelectron HDR unit was used to deliver a dose of 50cGy to the mid-plane of a 62mm thick solid water phantom using dwell times from Monte Carlo pre-calculated nomograms for a 60mm, 70mm Round and 60mm Skin-Dose Optimized (SDO) applicators respectively. GafChromic EBT3+ film was embedded in the phantom midplane horizontally to measure dose distribution. Absolute dose was also measured with TLDs and an ADCL calibrated parallel-plate ion chamber placed in the film plane at fieldmore » center for each applicator. The film was calibrated using 6MV x-ray beam. TLDs were calibrated in a Cs-137 source at UW-Madison calibration laboratory. Radiation leakage through the tungsten alloy shell was measured with a film wrapped around outside surface of a 60mm Round applicator. Results: Measured maximum doses at field center are consistently lower than predicated by 5.8% for TLD, 8.8% for ion chamber, and 2.6% for EBT3+ film on average, with measurement uncertainties of 2.2%, 0.3%, and 2.9% for TLD, chamber, film respectively. The total standard uncertainties for ion chamber and Gafchromic film measurement are 4.9% and 4.6% respectively[1]. The area defined by the applicator aperture was covered by 80% of maximum dose for 62mm compression thickness. When 100cGy is delivered to mid-plane with a 60mm Round applicator, surface dose ranges from 60cGy to a maximum of 145cGy, which occurs at source entrance to the applicator. Conclusion: Measured doses by all three techniques are consistently lower than predicted in our measurements. For a compression thickness of 62 mm, the field size defined by the applicator is only covered by 80% of prescribed dose. Radiation leakage of up to 145cGy was found at the source entrance of applicators.« less

Investigation of the effect of UV-LED exposure conditions on the production of vitamin D in pig skin.

PubMed

Barnkob, Line Lundbæk; Argyraki, Aikaterini; Petersen, Paul Michael; Jakobsen, Jette

2016-12-01

The dietary intake of vitamin D is currently below the recommended intake of 10-20μg vitamin D/day. Foods with increased content of vitamin D or new products with enhanced vitamin D are warranted. Light-emitting diodes (LEDs) are a potential new resource in food production lines. In the present study the exposure conditions with ultraviolet (UV) LEDs were systematically investigated in the wavelength range 280-340nm for achieving optimal vitamin D bio-fortification in pig skin. A wavelength of 296nm was found to be optimal for vitamin D3 production. The maximum dose of 20kJ/m(2) produced 3.5-4μg vitamin D3/cm(2) pig skin. Vitamin D3 produced was independent on the combination of time and intensity of the LED source. The increased UV exposure by UV-LEDs may be readily implemented in existing food production facilities, without major modifications to the process or processing equipment, for bio-fortifying food products containing pork skin. Copyright © 2016 Elsevier Ltd. All rights reserved.

Biochemical changes in the skin of rats exposed to radiation against the background of thermal stress. [X rays; ATPase and creatine kinase activities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matyushichev, V.B.; Taratukhin, V.R.; Shamratova, V.G.

1978-01-01

The effectiveness of exposing rats to different doses of x radiation after submitting them to a heat load, according to the tests of ATPase and creatine kinase activity of aqueous extracts of skin at the relatively late observation period was compared. The effects of the combined factors were monitored by means of a heat load (one group) and exposure to radiation alone in doses of 25, 50, 100, 250, and 400 R (5 groups). The obtained data are indicative of marked specificity of ATPase and creatine kinase reactions to the combined factors. Creatine kinase activity undergoes a 157% change, whereasmore » the mean relative deviation of ATPase activity constitutes only 71% of the normal level. The most effect loads are 36/sup 0/C + 25 R and 36/sup 0/C + 400 R. With all tested doses the extent of the effect of radiation on creatine kinase activity is only negligibly lower than the effectiveness of combined loads, whereas according to the ATPase test, radiation alone induces virtually the same changes in activity as combined factors. ATPase undergoes maximum change after irradiation in doses of 250 and 400 R; delivery of 25 to 100 R is associated with much less marked changes in activity. In contrast, creatine kinase demonstrates maximum sensitivity to radiation in a dosage of 25 R and minimum sensitivity, with a dosage of 100 R. Thermal stress (according to ATPase and creatine kinase activity) has a profound and quite substantial effect on processes of development of radiation lesion. It can be manifested by complete or partial summation of effects of each of the factors, mutual attenuation of effects, or absence of interaction between factors in the combination. All this is indicative of the complexity and differences in mechanisms of expression of effects of the factors used. (ERB)« less

Gating window dependency on scanned carbon-ion beam dose distribution and imaging dose for thoracoabdominal treatment.

PubMed

Mori, Shinichiro; Karube, Masataka; Yasuda, Shigeo; Yamamoto, Naoyoshi; Tsuji, Hiroshi; Kamada, Tadashi

2017-06-01

To explore the trade-off between dose assessment and imaging dose in respiratory gating with radiographic fluoroscopic imaging, we evaluated the relationship between dose assessment and fluoroscopic imaging dose in various gating windows, retrospectively. Four-dimensional (4D) CT images acquired for 10 patients with lung and liver tumours were used for 4D treatment planning for scanned carbon ion beam. Imaging dose from two oblique directions was calculated by the number of images multiplied by the air kerma per image. Necessary beam-on time was calculated from the treatment log file. Accumulated dose distribution was calculated. The gating window was defined as tumour position not respiratory phase and changed from 0-100% duty cycle on 4DCT. These metrics were individually evaluated for every case. For lung cases, sufficient dose conformation was achieved in respective gating windows [D 95 -clinical target volume (CTV) > 99%]. V 20 -lung values for 50%- and 30%-duty cycles were 2.5% and 6.0% of that for 100%-duty cycle. Maximum doses (cord/oesophagus) for 30%-duty cycle decreased 6.8%/7.4% to those for 100%-duty cycle. For liver cases, V 10 -liver values for 50%- and 30%-duty cycles were 9.4% and 12.8% of those for 100%-duty cycle, respectively. Maximum doses (cord/oesophagus) for 50%- and 30%-duty cycles also decreased 17.2%/19.3% and 24.6%/29.8% to those for 100%-duty cycle, respectively. Total imaging doses increased 43.5% and 115.8% for 50%- and 30%-duty cycles to that for the 100%-duty cycle. When normal tissue doses are below the tolerance level, the gating window should be expanded to minimize imaging dose and treatment time. Advances in knowledge: The skin dose from imaging might not be counterbalanced to the OAR dose; however, imaging dose is a particularly important factor.

MOSFET detectors in quality assurance of tomotherapy treatments.

PubMed

Cherpak, Amanda; Studinski, Ryan C N; Cygler, Joanna E

2008-02-01

The purpose of this work was to characterize metal oxide semiconductor field-effect transistors (MOSFETs) in a 6 MV conventional linac and investigate their use for quality assurance of radiotherapy treatments with a tomotherapy Hi-Art unit. High sensitivity and standard sensitivity MOSFETs were first calibrated and then tested for reproducibility, field size dependence, and accuracy of measuring surface dose in a 6 MV beam as well as in a tomotherapy Hi-Art unit. In vivo measurements were performed on both a RANDO phantom and several head and neck cancer patients treated with tomotherapy and compared to TLD measurements and treatment plan doses to evaluate the performance of MOSFETs in a high gradient radiation field. The average calibration factor found was 0.345+/-2.5%cGy/mV for the high sensitivity MOSFETs tested and 0.901+/-2.4%cGy/mV for the standard sensitivity MOSFETs. MOSFET measured surface doses had an average agreement with ion chamber measurements of 1.55% for the high sensitivity MOSFET and 5.23% for the standard sensitivity MOSFET when averaged over all trials and field sizes tested. No significant dependence on field size was found for the standard sensitivity MOSFETs, however a maximum difference of 5.34% was found for the high sensitivity MOSFET calibration factors in the field sizes tested. Measurements made with MOSFETS on head and neck patients treated on a tomotherapy Hi-Art unit had an average agreement of (3.26+/-0.03)% with TLD measurements, however the average of the absolute difference between the MOSFET measurements and the treatment plan skin doses was (12.2+/-7.5)%. The MOSFET measured patient skin doses also had good reproducibility, with inter-fraction deviations ranging from 1.4% to 6.6%. Similar results were found from trials using a RANDO phantom. The MOSFETs performed well when used in the tomotherapy Hi-Art unit and did not increase the overall treatment set-up time when used for patient measurements. It was found that MOSFETs are suitable detectors for surface dose measurements in both conventional beam and tomotherapy treatments and they can provide valuable skin dose information in areas where the treatment planning system may not be accurate.

9 CFR 381.168 - Maximum percent of skin in certain poultry products.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Maximum percent of skin in certain poultry products. 381.168 Section 381.168 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE... Standards of Identity or Composition § 381.168 Maximum percent of skin in certain poultry products. The...

9 CFR 381.168 - Maximum percent of skin in certain poultry products.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 9 Animals and Animal Products 2 2011-01-01 2011-01-01 false Maximum percent of skin in certain poultry products. 381.168 Section 381.168 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE... Standards of Identity or Composition § 381.168 Maximum percent of skin in certain poultry products. The...

Comparative study on skin dose measurement using MOSFET and TLD for pediatric patients with acute lymphatic leukemia.

PubMed

Al-Mohammed, Huda I; Mahyoub, Fareed H; Moftah, Belal A

2010-07-01

The object of this study was to compare the difference of skin dose measured in patients with acute lymphatic leukemia (ALL) treated with total body irradiation (TBI) using metal oxide semiconductor field-effect transistors (mobile MOSFET dose verification system (TN-RD-70-W) and thermoluminescent dosimeters (TLD-100 chips, Harshaw/ Bicron, OH, USA). Because TLD has been the most-commonly used technique in the skin dose measurement of TBI, the aim of the present study is to prove the benefit of using the mobile MOSFET (metal oxide semiconductor field effect transistor) dosimeter, for entrance dose measurements during the total body irradiation (TBI) over thermoluminescent dosimeters (TLD). The measurements involved 10 pediatric patients ages between 3 and 14 years. Thermoluminescent dosimeters and MOSFET dosimetry were performed at 9 different anatomic sites on each patient. The present results show there is a variation between skin dose measured with MOSFET and TLD in all patients, and for every anatomic site selected, there is no significant difference in the dose delivered using MOSFET as compared to the prescribed dose. However, there is a significant difference for every anatomic site using TLD compared with either the prescribed dose or MOSFET. The results indicate that the dosimeter measurements using the MOSFET gave precise measurements of prescribed dose. However, TLD measurement showed significant increased skin dose of cGy as compared to either prescribed dose or MOSFET group. MOSFET dosimeters provide superior dose accuracy for skin dose measurement in TBI as compared with TLD.

Radiation-Induced Skin Injuries to Patients: What the Interventional Radiologist Needs to Know.

PubMed

Jaschke, Werner; Schmuth, Matthias; Trianni, Annalisa; Bartal, Gabriel

2017-08-01

For a long time, radiation-induced skin injuries were only encountered in patients undergoing radiation therapy. In diagnostic radiology, radiation exposures of patients causing skin injuries were extremely rare. The introduction of fast multislice CT scanners and fluoroscopically guided interventions (FGI) changed the situation. Both methods carry the risk of excessive high doses to the skin of patients resulting in skin injuries. In the early nineties, several reports of epilation and skin injuries following CT brain perfusion studies were published. During the same time, several papers reported skin injuries following FGI, especially after percutaneous coronary interventions and neuroembolisations. Thus, CT and FGI are of major concern regarding radiation safety since both methods can apply doses to patients exceeding 5 Gy (National Council on Radiation Protection and Measurements threshold for substantial radiation dose level). This paper reviews the problem of skin injuries observed after FGI. Also, some practical advices are given how to effectively avoid skin injuries. In addition, guidelines are discussed how to deal with patients who were exposed to a potentially dangerous radiation skin dose during medically justified interventional procedures.

The injury and cumulative effects on human skin by UV exposure from artificial fluorescence emission.

PubMed

Tian, Yan; Liu, Wei; Niu, TianHui; Dai, CaiHong; Li, Xiaoxin; Cui, Caijuan; Zhao, Xinyan; E, Yaping; Lu, Hui

2014-01-01

The injury and cumulative effects of UV emission from fluorescence lamp were studied. UV intensity from fluorescence lamp was measured, and human skin samples (hips, 10 volunteers) were exposed to low-dose UV irradiation (three times per week for 13 consecutive weeks). Three groups were examined: control group without UV radiation; low-dose group with a cumulative dose of 50 J cm(-2) which was equivalent to irradiation of the face during indoor work for 1.5 years; and high-dose group with 1000 J cm(-2) cumulative dose equivalent to irradiation of the face during outdoor activities for 1 year. Specific indicators were measured before and after UVA irradiation. The findings showed that extending the low-dose UVA exposure decreased the skin moisture content and increased the transepidermal water loss as well as induced skin color changes (decreased L* value, increased M index). Furthermore, irradiated skin showed an increased thickness of cuticle and epidermis, skin edema, light color and unclear staining collagen fibers in the dermis, and elastic fiber fragmentation. In addition, MMP-1, p53 and SIRT1 expression was also increased. Long-term exposure of low-dose UVA radiation enhanced skin photoaging. The safety of the fluorescent lamp needs our attention. © 2014 The American Society of Photobiology.

Estimating peak skin and eye lens dose from neuroperfusion examinations: use of Monte Carlo based simulations and comparisons to CTDIvol, AAPM Report No. 111, and ImPACT dosimetry tool values.

PubMed

Zhang, Di; Cagnon, Chris H; Villablanca, J Pablo; McCollough, Cynthia H; Cody, Dianna D; Zankl, Maria; Demarco, John J; McNitt-Gray, Michael F

2013-09-01

CT neuroperfusion examinations are capable of delivering high radiation dose to the skin or lens of the eyes of a patient and can possibly cause deterministic radiation injury. The purpose of this study is to: (a) estimate peak skin dose and eye lens dose from CT neuroperfusion examinations based on several voxelized adult patient models of different head size and (b) investigate how well those doses can be approximated by some commonly used CT dose metrics or tools, such as CTDIvol, American Association of Physicists in Medicine (AAPM) Report No. 111 style peak dose measurements, and the ImPACT organ dose calculator spreadsheet. Monte Carlo simulation methods were used to estimate peak skin and eye lens dose on voxelized patient models, including GSF's Irene, Frank, Donna, and Golem, on four scanners from the major manufacturers at the widest collimation under all available tube potentials. Doses were reported on a per 100 mAs basis. CTDIvol measurements for a 16 cm CTDI phantom, AAPM Report No. 111 style peak dose measurements, and ImPACT calculations were performed for available scanners at all tube potentials. These were then compared with results from Monte Carlo simulations. The dose variations across the different voxelized patient models were small. Dependent on the tube potential and scanner and patient model, CTDIvol values overestimated peak skin dose by 26%-65%, and overestimated eye lens dose by 33%-106%, when compared to Monte Carlo simulations. AAPM Report No. 111 style measurements were much closer to peak skin estimates ranging from a 14% underestimate to a 33% overestimate, and with eye lens dose estimates ranging from a 9% underestimate to a 66% overestimate. The ImPACT spreadsheet overestimated eye lens dose by 2%-82% relative to voxelized model simulations. CTDIvol consistently overestimates dose to eye lens and skin. The ImPACT tool also overestimated dose to eye lenses. As such they are still useful as a conservative predictor of dose for CT neuroperfusion studies. AAPM Report No. 111 style measurements are a better predictor of both peak skin and eye lens dose than CTDIvol and ImPACT for the patient models used in this study. It should be remembered that both the AAPM Report No. 111 peak dose metric and CTDIvol dose metric are dose indices and were not intended to represent actual organ doses.

Estimating peak skin and eye lens dose from neuroperfusion examinations: Use of Monte Carlo based simulations and comparisons to CTDIvol, AAPM Report No. 111, and ImPACT dosimetry tool values

PubMed Central

Zhang, Di; Cagnon, Chris H.; Villablanca, J. Pablo; McCollough, Cynthia H.; Cody, Dianna D.; Zankl, Maria; Demarco, John J.; McNitt-Gray, Michael F.

2013-01-01

Purpose: CT neuroperfusion examinations are capable of delivering high radiation dose to the skin or lens of the eyes of a patient and can possibly cause deterministic radiation injury. The purpose of this study is to: (a) estimate peak skin dose and eye lens dose from CT neuroperfusion examinations based on several voxelized adult patient models of different head size and (b) investigate how well those doses can be approximated by some commonly used CT dose metrics or tools, such as CTDIvol, American Association of Physicists in Medicine (AAPM) Report No. 111 style peak dose measurements, and the ImPACT organ dose calculator spreadsheet. Methods: Monte Carlo simulation methods were used to estimate peak skin and eye lens dose on voxelized patient models, including GSF's Irene, Frank, Donna, and Golem, on four scanners from the major manufacturers at the widest collimation under all available tube potentials. Doses were reported on a per 100 mAs basis. CTDIvol measurements for a 16 cm CTDI phantom, AAPM Report No. 111 style peak dose measurements, and ImPACT calculations were performed for available scanners at all tube potentials. These were then compared with results from Monte Carlo simulations. Results: The dose variations across the different voxelized patient models were small. Dependent on the tube potential and scanner and patient model, CTDIvol values overestimated peak skin dose by 26%–65%, and overestimated eye lens dose by 33%–106%, when compared to Monte Carlo simulations. AAPM Report No. 111 style measurements were much closer to peak skin estimates ranging from a 14% underestimate to a 33% overestimate, and with eye lens dose estimates ranging from a 9% underestimate to a 66% overestimate. The ImPACT spreadsheet overestimated eye lens dose by 2%–82% relative to voxelized model simulations. Conclusions: CTDIvol consistently overestimates dose to eye lens and skin. The ImPACT tool also overestimated dose to eye lenses. As such they are still useful as a conservative predictor of dose for CT neuroperfusion studies. AAPM Report No. 111 style measurements are a better predictor of both peak skin and eye lens dose than CTDIvol and ImPACT for the patient models used in this study. It should be remembered that both the AAPM Report No. 111 peak dose metric and CTDIvol dose metric are dose indices and were not intended to represent actual organ doses. PMID:24007152

Estimation of human percutaneous bioavailability for two novel brominated flame retardants, 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (EH-TBB) and bis(2-ethylhexyl) tetrabromophthalate (BEH-TEBP)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knudsen, Gabriel A., E-mail: gabriel.knudsen@nih.g

2-Ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB) and bis(2-ethylhexyl)tetrabromophthalate (BEH-TEBP) are novel brominated flame retardants used in consumer products. A parallelogram approach was used to predict human dermal absorption and flux for EH-TBB and BEH-TEBP. [{sup 14}C]-EH-TBB or [{sup 14}C]-BEH-TEBP was applied to human or rat skin at 100 nmol/cm{sup 2} using a flow-through system. Intact rats received analogous dermal doses. Treated skin was washed and tape-stripped to remove “unabsorbed” [{sup 14}C]-radioactivity after continuous exposure (24 h). “Absorbed” was quantified using dermally retained [{sup 14}C]-radioactivity; “penetrated” was calculated based on [{sup 14}C]-radioactivity in media (in vitro) or excreta + tissues (in vivo). Human skin absorbedmore » EH-TBB (24 ± 1%) while 0.2 ± 0.1% penetrated skin. Rat skin absorbed more (51 ± 10%) and was more permeable (2 ± 0.5%) to EH-TBB in vitro; maximal EH-TBB flux was 11 ± 7 and 102 ± 24 pmol-eq/cm{sup 2}/h for human and rat skin, respectively. In vivo, 27 ± 5% was absorbed and 13% reached systemic circulation after 24 h (maximum flux was 464 ± 65 pmol-eq/cm{sup 2}/h). BEH-TEBP in vitro penetrance was minimal (< 0.01%) for rat or human skin. BEH-TEBP absorption was 12 ± 11% for human skin and 41 ± 3% for rat skin. In vivo, total absorption was 27 ± 9%; 1.2% reached systemic circulation. In vitro maximal BEH-TEBP flux was 0.3 ± 0.2 and 1 ± 0.3 pmol-eq/cm{sup 2}/h for human and rat skin; in vivo maximum flux for rat skin was 16 ± 7 pmol-eq/cm{sup 2}/h. EH-TBB was metabolized in rat and human skin to tetrabromobenzoic acid. BEH-TEBP-derived [{sup 14}C]-radioactivity in the perfusion media could not be characterized. < 1% of the dose of EH-TBB and BEH-TEHP is estimated to reach the systemic circulation following human dermal exposure under the conditions tested. Chemical compounds studied in this article: 2-Ethylhexyl 2,3,4,5-tetrabromobenzoate (PubChem CID: 71316600; CAS No. 183658-27-7 FW: 549.92 g/mol logP{sub est}: 7.73–8.75 (12)) Abdallah et al., 2015a. Other published abbreviations for 2-ethylhexyl-2,3,4,5-tetrabromobenzoate are TBB EHTeBB or EHTBB Abdallah and Harrad, 2011. bis(2-ethylhexyl) tetrabromophthalate (PubChem CID: 117291; CAS No. 26040-51-7 FW: 706.14 g/mol logP{sub est}: 9.48-11.95 (12)). Other published abbreviations for bis(2-ethylhexyl)tetrabromophthalate are TeBrDEPH TBPH or BEHTBP. - Highlights: • Human skin maximal flux was 11 ± 7 (EH-TBB) & 0.3 ± 0.2 (BEH-TEBP) pmol-eq/cm{sup 2}/h. • Predicted systemic bioavailability was < 1% for either chemical after 24 h. • Skin retained EH-TBB & BEH-TEBP after 24 h dermal exposure. • EH-TBB was hydrolyzed to tetrabromobenzoic acid; BEH-TEBP was not metabolized. • Skin contact is an important route of human exposure to EH-TBB & BEH-TEBP.« less

Dietary Aloe Vera Supplementation Improves Facial Wrinkles and Elasticity and It Increases the Type I Procollagen Gene Expression in Human Skin in vivo

PubMed Central

Cho, Soyun; Lee, Serah; Lee, Min-Jung; Lee, Dong Hun; Won, Chong-Hyun; Kim, Sang Min

2009-01-01

Background No studies have yet been undertaken to determine the effect of aloe gel on the clinical signs and biochemical changes of aging skin. Objective We wanted to determine whether dietary aloe vera gel has anti-aging properties on the skin. Methods Thirty healthy female subjects over the age of 45 were recruited and they received 2 different doses (low-dose: 1,200 mg/d, high-dose: 3,600 mg/d) of aloe vera gel supplementation for 90 days. Their baseline status was used as a control. At baseline and at completion of the study, facial wrinkles were measured using a skin replica, and facial elasticity was measured by an in vivo suction skin elasticity meter. Skin samples were taken before and after aloe intake to compare the type I procollagen and matrix metalloproteinase 1 (MMP-1) mRNA levels by performing real-time RT-PCR. Results After aloe gel intake, the facial wrinkles improved significantly (p<0.05) in both groups, and facial elasticity improved in the lower-dose group. In the photoprotected skin, the type I procollagen mRNA levels were increased in both groups, albeit without significance; the MMP-1 mRNA levels were significantly decreased in the higher-dose group. Type I procollagen immunostaining was substantially increased throughout the dermis in both groups. Conclusion Aloe gel significantly improves wrinkles and elasticity in photoaged human skin, with an increase in collagen production in the photoprotected skin and a decrease in the collagen-degrading MMP-1 gene expression. However, no dose-response relationship was found between the low-dose and high-dose groups. PMID:20548848

Importance of a Patient Dosimetry and Clinical Follow-up Program in the Detection of Radiodermatitis After Long Percutaneous Coronary Interventions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vano, Eliseo, E-mail: eliseov@med.ucm.es; Escaned, Javier; Vano-Galvan, Sergio

Complex percutaneous interventions often require high radiation doses likely to produce skin radiation injuries. We assessed the methodology used to select patients with potential skin injuries in cardiac procedures and in need of clinical follow-up. We evaluated peak skin dose and clinical follow-up in a case of radiodermatitis produced during a total occlusion recanalization. This prospective study followed CIRSE and ACC/AHA/SCAI recommendations for patient radiation dose management in interventional procedures carried out in a university hospital with a workload of 4200 interventional cardiac procedures per year. Patient dose reports were automatically transferred to a central database. Patients exceeding trigger levelsmore » for air kerma area product (500 Gy cm{sup 2}) and cumulative skin dose (5 Gy) were counseled and underwent follow-up for early detection of skin injuries, with dermatologic support. The Ethical Committee and the Quality Assurance and Radiation Safety Committee approved the program. During 2010, a total of 13 patients (3.0/1,000 that year) received dose values exceeding trigger levels in the cardiovascular institute. Only one patient, who had undergone two consecutive procedures resulting in 970 Gy cm{sup 2} and 13.0 Gy as cumulative skin dose, showed signs of serious radiodermatitis that resolved in 3.7 months. The remaining patients did not manifest skin lesions during follow-up, and whenever patient examination was not feasible as part of the follow-up, neither patients nor families reported any skin injuries. Peak skin dose calculation and close clinical follow-up were feasible and appropriate, with a moderate additional workload for the staff and satisfaction for the patient.« less

Skin autofluorescence reflects individual seasonal UV exposure, skin photodamage and skin cancer development in organ transplant recipients.

PubMed

Togsverd-Bo, Katrine; Philipsen, Peter Alshede; Hædersdal, Merete; Wulf, Hans Christian Olsen

2018-01-01

Ultraviolet radiation (UVR)-induced skin cancers varies among organ transplant recipients (OTRs). To improve individual risk assessment of skin cancer, objectively quantified skin photodamage is needed. We measured personal UVR-exposure dose in OTRs and assessed the relation between individual UVR exposure, skin cancer and objectively measured photodamage in terms of skin autofluorescence, pigmentation, and black light-evaluated solar lentigines. Danish OTRs with (n=15) and without a history of skin cancer (n=15) kept sun diaries from May to September and wore personal dosimeters recording time-stamped UVR doses in standard erythema doses (SED). Photodamage was quantified as skin autofluorescence with excitation at 370nm (F370) and 430nm (F430), skin pigmentation (pigment protection factor, PPF), and black light-evaluated solar lentigines. OTRs with skin cancer received a higher UVR dose than OTRs without skin cancer (median 116 SED vs. 67 SED, p=0.07) and UVR exposure doses were correlated with increased PPF (p=0.052) and F370 on the shoulder (F370 shoulder ) (p=0.04). We found that skin cancer was associated with F370 shoulder (OR 10.53, CI 3.3-31,938; p=0.018) and time since transplantation (OR 1.34, CI 0.95-1.91, p=0.097). A cut-off at 7.2 arbitrary units, 89% of OTRs with skin cancer had F370 shoulder values above 7.2 arbitrary units and F370 shoulder was additionally related to patient age (p=0.09) and black light-evaluated solar lentigines (p=0.04). F370 autofluorescence indicates objectively measured photodamage and may be used for individual risk assessment of skin cancer development in OTRs. Copyright © 2017. Published by Elsevier B.V.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knudsen, Gabriel A., E-mail: gabriel.knudsen@nih.gov; Hughes, Michael F.; McIntosh, Katelyn L.

Tetrabromobisphenol A (TBBPA) is currently the world's highest production volume brominated flame retardant. Humans are frequently exposed to TBBPA by the dermal route. In the present study, a parallelogram approach was used to make predictions of internal dose in exposed humans. Human and rat skin samples received 100 nmol of TBBPA/cm{sup 2} skin and absorption and penetrance were determined using a flow-through in vitro system. TBBPA-derived [{sup 14}C]-radioactivity was determined at 6 h intervals in the media and at 24 h post-dosing in the skin. The human skin and media contained an average of 3.4% and 0.2% of the totalmore » dose at the terminal time point, respectively, while the rat skin and media contained 9.3% and 3.5%, respectively. In the intact rat, 14% of a dermally-administered dose of ~ 100 nmol/cm{sup 2} remained in the skin at the dosing site, with an additional 8% reaching systemic circulation by 24 h post-dosing. Relative absorption and penetrance were less (10% total) at 24 h following dermal administration of a ten-fold higher dose (~ 1000 nmol/cm{sup 2}) to rats. However, by 72 h, 70% of this dose was either absorbed into the dosing-site skin or had reached systemic circulation. It is clear from these results that TBBPA can be absorbed by the skin and dermal contact with TBBPA may represent a small but important route of exposure. Together, these in vitro data in human and rat skin and in vivo data from rats may be used to predict TBBPA absorption in humans following dermal exposure. Based on this parallelogram calculation, up to 6% of dermally applied TBBPA may be bioavailable to humans exposed to TBBPA. - Highlights: • Tetrabromobisphenol A is the brominated flame retardant with highest global production volumes. • Humans are frequently exposed to TBBPA by the dermal route, especially via contaminated dust. • Human and rat skin data were integrated using a parallelogram method to predict human absorption. • TBBPA was dermally absorbed and skin contact may represent a small but important route of exposure. • Up to 6% of dermally applied TBBPA may be bioavailable to humans exposed to TBBPA.« less

A tracking system to calculate patient skin dose in real-time during neurointerventional procedures using a biplane x-ray imaging system.

PubMed

Rana, V K; Rudin, S; Bednarek, D R

2016-09-01

Neurovascular interventional procedures using biplane fluoroscopic imaging systems can lead to increased risk of radiation-induced skin injuries. The authors developed a biplane dose tracking system (Biplane-DTS) to calculate the cumulative skin dose distribution from the frontal and lateral x-ray tubes and display it in real-time as a color-coded map on a 3D graphic of the patient for immediate feedback to the physician. The agreement of the calculated values with the dose measured on phantoms was evaluated. The Biplane-DTS consists of multiple components including 3D graphic models of the imaging system and patient, an interactive graphical user interface, a data acquisition module to collect geometry and exposure parameters, the computer graphics processing unit, and functions for determining which parts of the patient graphic skin surface are within the beam and for calculating dose. The dose is calculated to individual points on the patient graphic using premeasured calibration files of entrance skin dose per mAs including backscatter; corrections are applied for field area, distance from the focal spot and patient table and pad attenuation when appropriate. The agreement of the calculated patient skin dose and its spatial distribution with measured values was evaluated in 2D and 3D for simulated procedure conditions using a PMMA block phantom and an SK-150 head phantom, respectively. Dose values calculated by the Biplane-DTS were compared to the measurements made on the phantom surface with radiochromic film and a calibrated ionization chamber, which was also used to calibrate the DTS. The agreement with measurements was specifically evaluated with variation in kVp, gantry angle, and field size. The dose tracking system that was developed is able to acquire data from the two x-ray gantries on a biplane imaging system and calculate the skin dose for each exposure pulse to those vertices of a patient graphic that are determined to be in the beam. The calculations are done in real-time with a typical graphic update time of 30 ms and an average vertex separation of 3 mm. With appropriate corrections applied, the Biplane-DTS was able to determine the entrance dose within 6% and the spatial distribution of the dose within 4% compared to the measurements with the ionization chamber and film for the SK150 head phantom. The cumulative dose for overlapping fields from both gantries showed similar agreement. The Biplane-DTS can provide a good estimate of the peak skin dose and cumulative skin dose distribution during biplane neurointerventional procedures. Real-time display of this information should help the physician manage patient dose to reduce the risk of radiation-induced skin injuries.

A tracking system to calculate patient skin dose in real-time during neurointerventional procedures using a biplane x-ray imaging system

PubMed Central

Rana, V. K.; Rudin, S.; Bednarek, D. R.

2016-01-01

Purpose: Neurovascular interventional procedures using biplane fluoroscopic imaging systems can lead to increased risk of radiation-induced skin injuries. The authors developed a biplane dose tracking system (Biplane-DTS) to calculate the cumulative skin dose distribution from the frontal and lateral x-ray tubes and display it in real-time as a color-coded map on a 3D graphic of the patient for immediate feedback to the physician. The agreement of the calculated values with the dose measured on phantoms was evaluated. Methods: The Biplane-DTS consists of multiple components including 3D graphic models of the imaging system and patient, an interactive graphical user interface, a data acquisition module to collect geometry and exposure parameters, the computer graphics processing unit, and functions for determining which parts of the patient graphic skin surface are within the beam and for calculating dose. The dose is calculated to individual points on the patient graphic using premeasured calibration files of entrance skin dose per mAs including backscatter; corrections are applied for field area, distance from the focal spot and patient table and pad attenuation when appropriate. The agreement of the calculated patient skin dose and its spatial distribution with measured values was evaluated in 2D and 3D for simulated procedure conditions using a PMMA block phantom and an SK-150 head phantom, respectively. Dose values calculated by the Biplane-DTS were compared to the measurements made on the phantom surface with radiochromic film and a calibrated ionization chamber, which was also used to calibrate the DTS. The agreement with measurements was specifically evaluated with variation in kVp, gantry angle, and field size. Results: The dose tracking system that was developed is able to acquire data from the two x-ray gantries on a biplane imaging system and calculate the skin dose for each exposure pulse to those vertices of a patient graphic that are determined to be in the beam. The calculations are done in real-time with a typical graphic update time of 30 ms and an average vertex separation of 3 mm. With appropriate corrections applied, the Biplane-DTS was able to determine the entrance dose within 6% and the spatial distribution of the dose within 4% compared to the measurements with the ionization chamber and film for the SK150 head phantom. The cumulative dose for overlapping fields from both gantries showed similar agreement. Conclusions: The Biplane-DTS can provide a good estimate of the peak skin dose and cumulative skin dose distribution during biplane neurointerventional procedures. Real-time display of this information should help the physician manage patient dose to reduce the risk of radiation-induced skin injuries. PMID:27587043

A tracking system to calculate patient skin dose in real-time during neurointerventional procedures using a biplane x-ray imaging system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rana, V. K., E-mail: vkrana@buffalo.edu

Purpose: Neurovascular interventional procedures using biplane fluoroscopic imaging systems can lead to increased risk of radiation-induced skin injuries. The authors developed a biplane dose tracking system (Biplane-DTS) to calculate the cumulative skin dose distribution from the frontal and lateral x-ray tubes and display it in real-time as a color-coded map on a 3D graphic of the patient for immediate feedback to the physician. The agreement of the calculated values with the dose measured on phantoms was evaluated. Methods: The Biplane-DTS consists of multiple components including 3D graphic models of the imaging system and patient, an interactive graphical user interface, amore » data acquisition module to collect geometry and exposure parameters, the computer graphics processing unit, and functions for determining which parts of the patient graphic skin surface are within the beam and for calculating dose. The dose is calculated to individual points on the patient graphic using premeasured calibration files of entrance skin dose per mAs including backscatter; corrections are applied for field area, distance from the focal spot and patient table and pad attenuation when appropriate. The agreement of the calculated patient skin dose and its spatial distribution with measured values was evaluated in 2D and 3D for simulated procedure conditions using a PMMA block phantom and an SK-150 head phantom, respectively. Dose values calculated by the Biplane-DTS were compared to the measurements made on the phantom surface with radiochromic film and a calibrated ionization chamber, which was also used to calibrate the DTS. The agreement with measurements was specifically evaluated with variation in kVp, gantry angle, and field size. Results: The dose tracking system that was developed is able to acquire data from the two x-ray gantries on a biplane imaging system and calculate the skin dose for each exposure pulse to those vertices of a patient graphic that are determined to be in the beam. The calculations are done in real-time with a typical graphic update time of 30 ms and an average vertex separation of 3 mm. With appropriate corrections applied, the Biplane-DTS was able to determine the entrance dose within 6% and the spatial distribution of the dose within 4% compared to the measurements with the ionization chamber and film for the SK150 head phantom. The cumulative dose for overlapping fields from both gantries showed similar agreement. Conclusions: The Biplane-DTS can provide a good estimate of the peak skin dose and cumulative skin dose distribution during biplane neurointerventional procedures. Real-time display of this information should help the physician manage patient dose to reduce the risk of radiation-induced skin injuries.« less

In vivo prostate IMRT dosimetry with MOSFET detectors using brass buildup caps

PubMed Central

Varadhan, Raj; Miller, John; Garrity, Brenden; Weber, Michael

2006-01-01

The feasibility of using dual bias metal oxide semiconductor field effect transistor (MOSFET) detectors with the new hemispherical brass buildup cap for in vivo dose measurements in prostate intensity‐modulated radiotherapy (IMRT) treatments was investigated and achieved. In this work, MOSFET detectors with brass buildup caps placed on the patient's skin surface on the central axis of the individual IMRT beams are used to determine the maximum entrance dose (Dmax) from the prostate IMRT fields. A general formalism with various correction factors taken into account to predict Dmax entrance dose for the IMRT fields with MOSFETs was developed and compared against predicted dose from the treatment‐planning system (TPS). We achieved an overall accuracy of better than ±5% on all measured fields for both 6‐MV and 10‐MV beams when compared to predicted doses from the Philips Pinnacle 3 and CMS XiO TPSs, respectively. We also estimate the total uncertainty in estimation of MOSFET dose in the high‐sensitivity mode for IMRT therapy to be 4.6%. PACS numbers: 87.53Xd, 87.56Fc PMID:17533354

Time and dose-response effects of honokiol on UVB-induced skin cancer development.

PubMed

Guillermo, Ruth F; Chilampalli, Chandeshwari; Zhang, Xiaoying; Zeman, David; Fahmy, Hesham; Dwivedi, Chandradhar

2012-06-01

Honokiol has shown chemopreventive effects in chemically-induced and UVB-induced skin cancer in mice. In this investigation, we assessed the time-effects of a topical low dose of honokiol (30 μg), and then the effects of different honokiol doses (30, 45, and 60 μg) on a UVB-induced skin cancer model to find an optimal dose and time for desirable chemopreventive effects. UVB radiation (30 mJ/cm(2), 5 days/week for 25 or 27 weeks) was used to induce skin carcinogenesis in SKH-1 mice. For the time-response experiment 30 μg honokiol in acetone was applied topically to the animals before the UVB exposure (30 min, 1 h, and 2 h) and after the UVB exposure (immediately, 30 min, and 1 h). Control groups were treated with acetone. For the dose-response study, animals were treated topically with acetone or honokiol (30, 45, and 60 μg) one hour before the UVB exposure. In the time-response experiment, honokiol inhibited skin tumor multiplicity by 49-58% while reducing tumor volumes by 70-89%. In the dose-response study, honokiol (30, 45, and 60 μg) significantly decreased skin tumor multiplicity by 36-78% in a dose-dependent manner, while tumor area was reduced by 76-94%. Honokiol (60 μg) significantly reduced tumor incidence by 40% as compared to control group. Honokiol applied in very low doses (30 μg) either before or after UVB radiation shows chemopreventive effects. Honokiol (30, 45, and 60 μg) prevents UVB-induced skin cancer in a dose-dependent manner. Honokiol can be an effective chemopreventive agent against skin cancer.

SU-F-BRA-14: Optimization of Dosimetric Guidelines for Accelerated Partial Breast Irradiation (APBI) Using the Strut-Adjusted Volume Implant (SAVI)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mooney, K; Altman, M; Garcia-Ramirez, J

Purpose: Treatment planning guidelines for accelerated partial breast irradiation (ABPI) using the strut-adjusted volume implant (SAVI) are inconsistent between the manufacturer and NSABP B-39/RTOG 0413 protocol. Furthermore neither set of guidelines accounts for different applicator sizes. The purpose of this work is to establish guidelines specific to the SAVI that are based on clinically achievable dose distributions. Methods: Sixty-two consecutive patients were implanted with a SAVI and prescribed to receive 34 Gy in 10 fractions twice daily using high dose-rate (HDR) Ir-192 brachytherapy. The target (PTV-EVAL) was defined per NSABP. The treatments were planned and evaluated using a combination ofmore » dosimetric planning goals provided by the NSABP, the manufacturer, and our prior clinical experience. Parameters evaluated included maximum doses to skin and ribs, and volumes of PTV-EVAL receiving 90%, 95%, 100%, 150%, and 200% of the prescription (V90, etc). All target parameters were evaluated for correlation with device size using the Pearson correlation coefficient. Revised dosimetric guidelines for target coverage and heterogeneity were determined from this population. Results: Revised guidelines for minimum target coverage (ideal in parentheses): V90≥95%(97%), V95≥90%(95%), V100≥88%(91%). The only dosimetric parameters that were significantly correlated (p<0.05) with device size were V150 and V200. Heterogeneity criteria were revised for the 6–1 Mini/6-1 applicators to V150≤30cc and V200≤15cc, and unchanged for the other sizes. Re-evaluation of patient plans showed 90% (56/62) met the revised minimum guidelines and 76% (47/62) met the ideal guidelines. All and 56/62 patients met our institutional guidelines for maximum skin and rib dose, respectively. Conclusions: We have optimized dosimetric guidelines for the SAVI applicators, and found that implementation of these revised guidelines for SAVI treatment planning yielded target coverage exceeding that required by existing guidelines while preserving heterogeneity constraints and minimizing dose to organs at risk.« less

Ultraviolet-B radiation increases serum 25-hydroxyvitamin D levels: the effect of UVB dose and skin color.

PubMed

Armas, Laura A G; Dowell, Susan; Akhter, Mohammed; Duthuluru, Sowjanya; Huerter, Christopher; Hollis, Bruce W; Lund, Richard; Heaney, Robert P

2007-10-01

Ultraviolet (UV)-B light increases vitamin D levels, but the dose response and the effect of skin pigmentation have not been well characterized. We sought to define the relationship between UVB exposure and 25-hydroxyvitamin D (25-OH-D) concentrations as a function of skin pigmentation. Seventy two participants with various skin tones had 90% of their skin exposed to UVB light (20-80 mJ/cm2) 3 times a week for 4 weeks. Serum 25-OH-D was measured weekly. Eighty percent of the variation in treatment response was explained by UVB dose and skin tone. Therapeutically important changes in 25-OH-D were achieved with minimal tanning. Four weeks was not long enough to reach a steady state at the higher dose rates. The response of 25-OH-D levels to UVB light is dependent on skin pigmentation and the amount of UVB given, and useful increases in vitamin D status can be achieved by defined UVB doses small enough to produce only minimal tanning.

Fractional sunburn threshold UVR doses generate equivalent vitamin D and DNA damage in skin types I-VI, but with epidermal DNA damage gradient correlated to skin darkness.

PubMed

Shih, Barbara B; Farrar, Mark D; Cooke, Marcus S; Osman, Joanne; Langton, Abigail K; Kift, Richard; Webb, Ann R; Berry, Jacqueline L; Watson, Rachel E B; Vail, Andy; de Gruijl, Frank R; Rhodes, Lesley E

2018-05-03

Public health guidance recommends limiting sun-exposure to sub-sunburn levels, but it's unknown whether these can gain vitamin D (for musculoskeletal health) whilst avoiding epidermal DNA damage (initiates skin cancer). Well-characterised healthy humans of all skin types (I-VI; lightest to darkest skin) were exposed to a low dose-series of solar simulated UVR of 20-80% their individual sunburn threshold dose (minimal erythemal dose, MED). Significant UVR dose-responses were seen for serum 25(OH)D and whole epidermal CPD, with as little as 0.2 MED concurrently producing 25(OH)D and CPD. Notably, fractional MEDs generated equivalent levels of whole epidermal CPD and 25(OH)D across all skin types. Crucially, we demonstrated an epidermal gradient of CPD formation strongly correlated with skin darkness (r=0.74; P<0.0001), which reflected melanin content and revealed increasing protection across the skin types, ranging from darkest skin, where high CPD levels occurred superficially with none in the germinative basal layer, through to lightest skin where CPD were induced evenly across the epidermal depth. Darker skin people can be encouraged to utilise sub-sunburn UVR-exposure to enhance their vitamin D. In lighter skin people, basal cell damage occurs concurrent with vitamin D synthesis at exquisitely low UVR levels, providing an explanation for their high skin cancer incidence; greater caution is required. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

SU-F-T-509: Investigation into the Impact of the Linear Accelerator Treatment Table On Skin Dose to Prone Breast Patients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pedersen, K; Irwin, J; Sansourekidou, P

Purpose: To investigate the impact of the treatment table on skin dose for prone breast patients for which the breast contacts the table and to develop a method to decrease skin dose. Methods: We used 12cm stack of 15cmx15cm solid water slabs to imitate breast. Calibrated EBT3 radiochromic film was affixed to the bottom of the phantom. Treatments for 32 patients were analyzed to determine typical prone breast beam parameters. Based on the analysis, a field size and a range of gantry angles were chosen for the test beams. Three experimental setups were used. The first represented the patient setupmore » currently used in our clinics with the phantom directly on the table. The second was the skin sparing setup, with a 1.5cm Styrofoam slab between the phantom and the table. The third used a 7.5cm Styrofoam slab to examine the extent of skin sparing potential. The calibration curve was applied to each film to determine dose. Percent difference in dose between the current and skin sparing setups was calculated for each gantry angle and gantry angle pair. Results: Data showed that beams entering through the table showed a skin dose decrease ranging from 13%–30% with the addition of 7.5cm Styrofoam, while beams exiting through the table showed no significant difference. The addition of 1.5cm Styrofoam resulted in differences ranging from 0.5%–13% with the skin sparing setup. Conclusion: The results demonstrate that skin in contact with the table receives increased dose from beams entering through the table. By creating separation between the breast and the table with Styrofoam the skin dose can be lowered, but 1.5 cm did not fully mitigate the effect. Further investigation will be performed to identify a clinically practical thickness that maximizes this mitigation.« less

A new radiotherapy surface dose detector:the MOSFET.

PubMed

Butson, M J; Rozenfeld, A; Mathur, J N; Carolan, M; Wong, T P; Metcalfe, P E

1996-05-01

Radiotherapy x-ray and electron beam surface doses are accurately measurable by use of a MOS-FET detector system. The MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is approximately 200-microns in diameter and consists of a 0.5-microns Al electrode on top of a 1-microns SiO2 and 300-microns Si substrate. Results for % surface dose were within +/- 2% compared to the Attix chamber and within +/- 3% of TLD extrapolation results for normally incident beams. Detectors were compared using different energies, field size, and beam modifying devices such as block trays and wedges. Percentage surface dose for 10 x 10-cm and 40 x 40-cm field size for 6-MV x rays at 100-cm SSD using the MOSFET were 16% and 42% of maximum, respectively. Factors such as its small size, immediate retrieval of results, high accuracy attainable from low applied doses, and as the MOSFET records its dose history make it a suitable in vivo dosimeter where surface and skin doses need to be determined. This can be achieved within part of the first fraction of dose (i.e., only 10 cGy is required.)

Skin dose for head and neck cancer patients treated with intensity-modulated radiation therapy(IMRT)

NASA Astrophysics Data System (ADS)

Fu, Hsiao-Ju; Li, Chi-Wei; Tsai, Wei-Ta; Chang, Chih-Chia; Tsang, Yuk-Wah

2017-11-01

The reliability of thermoluminescent dosimeters (ultrathin TLD) and ISP Gafchromic EBT2 film to measure the surface dose in phantom and the skin dose in head-and-neck patients treated with intensity-modulated radiation therapy technique(IMRT) is the research focus. Seven-field treatment plans with prescribed dose of 180 cGy were performed on Eclipse treatment planning system which utilized pencil beam calculation algorithm(PBC). In calibration tests, the variance coefficient of the ultrathin TLDs were within 3%. The points on the calibration curve of the Gafchromic film was within 1% variation. Five measurements were taken on phantom using ultrathin TLD and EBT2 film respectively. The measured mean surface doses between ultrathin TLD or EBT2 film were within 5% deviation. Skin doses of 6 patients were measured for initial 5 fractions and the mean dose per-fraction was calculated. If the extrapolated doses for 30 fractions were below 4000 cGy, the skin reaction grading observed according to Radiation Therapy Oncology Group (RTOG) was either grade 1 or grade 2. If surface dose exceeded 5000 cGy in 32 fractions, then grade 3 skin reactions were observed.

The Effects of Low Dose Irradiation on Inflammatory Response Proteins in a 3D Reconstituted Human Skin Tissue Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varnum, Susan M.; Springer, David L.; Chaffee, Mary E.

Skin responses to moderate and high doses of ionizing radiation include the induction of DNA repair, apoptosis, and stress response pathways. Additionally, numerous studies indicate that radiation exposure leads to inflammatory responses in skin cells and tissue. However, the inflammatory response of skin tissue to low dose radiation (<10 cGy) is poorly understood. In order to address this, we have utilized a reconstituted human skin tissue model (MatTek EpiDerm FT) and assessed changes in 23 cytokines twenty-four and forty eight hours following treatment of skin with either 3 or 10 cGy low-dose of radiation. Three cytokines, IFN-γ, IL-2, MIP-1α, weremore » significantly altered in response to low dose radiation. In contrast, seven cytokines were significantly altered in response to a high radiation dose of 200 cGy (IL-2, IL-10, IL-13, IFN-γ, MIP-1α, TNF α, and VEGF) or the tumor promoter 12-O-tetradecanoylphorbol 13-acetate (G-CSF, GM-CSF, IL-1α, IL-8, MIP-1α, MIP-1β, RANTES). Additionally, radiation induced inflammation appears to have a distinct cytokine response relative to the non-radiation induced stressor, TPA. Overall, these results indicate that there are subtle changes in the inflammatory protein levels following exposure to low dose radiation and this response is a sub-set of what is seen following a high dose in a human skin tissue model.« less

Comparison of skin responses from macroscopic and microscopic UV challenges

NASA Astrophysics Data System (ADS)

Seo, InSeok; Bargo, Paulo R.; Chu, Melissa; Ruvolo, Eduardo; Kollias, Nikiforos

2011-03-01

The minimal erythema dose induced by solar-simulated radiation is a useful measure of UV sensitivity of skin. Most skin phototests have been conducted by projecting a flat field of UV radiation onto the skin in an area greater than 15 cm × 15 cm with an increment of radiation doses. In this study, we investigated the responses of human skin to solar-simulated radiation of different field sizes. Twelve human subjects of skin phototype I-IV were exposed to solar-simulated radiation (SSR) on their upper inner arm or on their lower back with a series of doses in increments of 20% in order to determine the threshold dose to induce a minimal perceptible erythema response (MED). Each dose was delivered with a liquid light guide (8 mm diameter on the back or 6 mm on the upper inner arm) and with quartz optical fibers of 200 μm diameter. The resulting skin responses were evaluated visually and investigated with a reflectance confocal microscope and imaging. The erythema response to the microscopic challenge was always diffuse with no clear boundaries extending to several times the exposed site diameter at doses greater than 2 MED. The skin returned to normal appearance from the microscopic challenge after two weeks of exposure while change in appearance for the larger areas persisted for several weeks to months. This new modality of testing provides the possibility to study skin at the microscopic level with a rapid recovery following challenge.

In vitro dermal disposition of abamectin (avermectin B(1)) in livestock.

PubMed

Baynes, Ronald E

2004-06-01

Many avermectins are approved for topical application in domestic animals. However, extralabel use may result in significant dermal absorption and consequently the potential for adverse effects or violative residues. The primary aim of this study was to assess dermal disposition of abamectin in vitro in bovine, caprine, ovine, and porcine skin dosed in 100% isopropanol, commercial alcohol-based (Ivomec), or oil-based (Eprinex) formulations. Skin sections were perfused in a flow-through diffusion cell system for 8 h, and the disposition of radiolabel abamectin was determined from perfusate and skin samples. Abamectin absorption ranged from 0.09% to 0.20% dose and there were no significant differences between formulations in each species. Isopropanol significantly increased skin deposition in all species when compared to the oil formulation. Absorption was significantly greater in bovine skin than in porcine skin for the isopropanol-containing formulations, but there were no significant species differences for the oil formulation. While significant levels (11.69-50.23% dose) remained on the skin surface, the highest levels deposited in viable skin were observed in caprine skin (28.09% dose) and the lowest levels were in porcine skin (1.50% dose) which could lead to systemic absorption. In summary, these 8-h experiments demonstrated that the alcohol-based formulations compared to oil-based formulations enhanced abamectin absorption and skin deposition in several animal species, and this effect is more likely to be observed in ruminant species than in porcine species.

Estimating cancer risk from dental cone-beam CT exposures based on skin dosimetry

NASA Astrophysics Data System (ADS)

Pauwels, Ruben; Cockmartin, Lesley; Ivanauskaité, Deimante; Urbonienė, Ausra; Gavala, Sophia; Donta, Catherine; Tsiklakis, Kostas; Jacobs, Reinhilde; Bosmans, Hilde; Bogaerts, Ria; Horner, Keith; SEDENTEXCT Project Consortium, The

2014-07-01

The aim of this study was to measure entrance skin doses on patients undergoing cone-beam computed tomography (CBCT) examinations, to establish conversion factors between skin and organ doses, and to estimate cancer risk from CBCT exposures. 266 patients (age 8-83) were included, involving three imaging centres. CBCT scans were acquired using the SCANORA 3D (Soredex, Tuusula, Finland) and NewTom 9000 (QR, Verona, Italy). Eight thermoluminescent dosimeters were attached to the patient's skin at standardized locations. Using previously published organ dose estimations on various CBCTs with an anthropomorphic phantom, correlation factors to convert skin dose to organ doses were calculated and applied to estimate patient organ doses. The BEIR VII age- and gender-dependent dose-risk model was applied to estimate the lifetime attributable cancer risk. For the SCANORA 3D, average skin doses over the eight locations varied between 484 and 1788 µGy. For the NewTom 9000 the range was between 821 and 1686 µGy for Centre 1 and between 292 and 2325 µGy for Centre 2. Entrance skin dose measurements demonstrated the combined effect of exposure and patient factors on the dose. The lifetime attributable cancer risk, expressed as the probability to develop a radiation-induced cancer, varied between 2.7 per million (age >60) and 9.8 per million (age 8-11) with an average of 6.0 per million. On average, the risk for female patients was 40% higher. The estimated radiation risk was primarily influenced by the age at exposure and the gender, pointing out the continuing need for justification and optimization of CBCT exposures, with a specific focus on children.

X-ray surface dose measurements using TLD extrapolation.

PubMed

Kron, T; Elliot, A; Wong, T; Showell, G; Clubb, B; Metcalfe, P

1993-01-01

Surface dose measurements in therapeutic x-ray beams are of importance in determining the dose to the skin of patients undergoing radiotherapy. Measurements were performed in the 6-MV beam of a medical linear accelerator with LiF thermoluminescence dosimeters (TLD) using a solid water phantom. TLD chips (surface area 3.17 x 3.17 cm2) of three different thicknesses (0.230, 0.099, and 0.038 g/cm2) were used to extrapolate dose readings to an infinitesimally thin layer of LiF. This surface dose was measured for field sizes ranging from 1 x 1 cm2 to 40 x 40 cm2. The surface dose relative to maximum dose was found to be 10.0% for a field size of 5 x 5 cm2, 16.3% for 10 x 10 cm2, and 26.9% for 20 x 20 cm2. Using a 6-mm Perspex block tray in the beam increased the surface dose in these fields to 10.7%, 17.7%, and 34.2% respectively. Due to the small size of the TLD chips, TLD extrapolation is applicable also for intracavity and exit dose determinations. The technique used for in vivo dosimetry could provide clinicians information about the build up of dose up to 1-mm depth in addition to an extrapolated surface dose measurement.

Hard beta and gamma emissions of 124I. Impact on occupational dose in PET/CT.

PubMed

Kemerink, G J; Franssen, R; Visser, M G W; Urbach, C J A; Halders, S G E A; Frantzen, M J; Brans, B; Teule, G J J; Mottaghy, F M

2011-01-01

The hard beta and gamma radiation of 124I can cause high doses to PET/CT workers. In this study we tried to quantify this occupational exposure and to optimize radioprotection. Thin MCP-Ns thermoluminescent dosimeters suitable for measuring beta and gamma radiation were used for extremity dosimetry, active personal dosimeters for whole-body dosimetry. Extremity doses were determined during dispensing of 124I and oral administration of the activity to the patient, the body dose during all phases of the PET/CT procedure. In addition, dose rates of vials and syringes as used in clinical practice were measured. The procedure for dispensing 124I was optimized using newly developed shielding. Skin dose rates up to 100 mSv/min were measured when in contact with the manufacturer's vial containing 370 MBq of 124I. For an unshielded 5 ml syringe the positron skin dose was about seven times the gamma dose. Before optimization of the preparation of 124I, using an already reasonably safe technique, the highest mean skin dose caused by handling 370 MBq was 1.9 mSv (max. 4.4 mSv). After optimization the skin dose was below 0.2 mSv. The highly energetic positrons emitted by 124I can cause high skin doses if radioprotection is poor. Under optimized conditions occupational doses are acceptable. Education of workers is of paramount importance.

Higher energy: is it necessary, is it worth the cost for radiation oncology?

PubMed

Das, I J; Kase, K R

1992-01-01

The physical characteristics of the interactions of megavoltage photons and electrons with matter provide distinct advantages, relative to low-energy (orthovoltage) x rays, that lead to better radiation dose distributions in patients. Use of these high-energy radiations has resulted in better patient care, which has been reflected in improved radiation treatment outcome in recent years. But, as the desire for higher energy radiation beams increases, it becomes important to determine whether the physical characteristics that make megavoltage beams beneficial continue to provide a net advantage. It is demonstrated that, in fact, there is an energy range from 4 to 15 MV for photons and 4 to 20 MeV for electrons that is optimally suited for the treatment of cancer in humans. Radiation beams that exceed these maximum energies were found to add no advantage. This is because the costs (price of unit, installation, maintenance, shielding for neutron and photons) are not justified by either improved physical characteristics of the radiation (penetration, skin sparing, dose distribution) or treatment outcome. In fact, for photon beams some physical characteristics result in less desirable dose distributions, less accurate dosimetry, and increased safety problems as the energy increases for example, increasingly diffuse beam edges, loss of electron equilibrium, uncertainty in dose perturbations at interfaces, increased neutron contamination, and potential for higher personnel dose. The special features that make electron beams useful at lower energies, for example, skin sparing and small penetration, are lost at high energies. These physical factors are analyzed together with the economic factors related to radiation therapy patient care using megavoltage beams.

SU-F-T-70: A High Dose Rate Total Skin Electron Irradiation Technique with A Specific Inter-Film Variation Correction Method for Very Large Electron Beam Fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, X; Rosenfield, J; Dong, X

2016-06-15

Purpose: Rotational total skin electron irradiation (RTSEI) is used in the treatment of cutaneous T-cell lymphoma. Due to inter-film uniformity variations the dosimetry measurement of a large electron beam of a very low energy is challenging. This work provides a method to improve the accuracy of flatness and symmetry for a very large treatment field of low electron energy used in dual beam RTSEI. Methods: RTSEI is delivered by dual angles field a gantry of ±20 degrees of 270 to cover the upper and the lower halves of the patient body with acceptable beam uniformity. The field size is inmore » the order of 230cm in vertical height and 120 cm in horizontal width and beam energy is a degraded 6 MeV (6 mm of PMMA spoiler). We utilized parallel plate chambers, Gafchromic films and OSLDs as a measuring devices for absolute dose, B-Factor, stationary and rotational percent depth dose and beam uniformity. To reduce inter-film dosimetric variation we introduced a new specific correction method to analyze beam uniformity. This correction method uses some image processing techniques combining film value before and after radiation dose to compensate the inter-variation dose response differences among films. Results: Stationary and rotational depth of dose demonstrated that the Rp is 2 cm for rotational and the maximum dose is shifted toward the surface (3mm). The dosimetry for the phantom showed that dose uniformity reduced to 3.01% for the vertical flatness and 2.35% for horizontal flatness after correction thus achieving better flatness and uniformity. The absolute dose readings of calibrated films after our correction matched with the readings from OSLD. Conclusion: The proposed correction method for Gafchromic films will be a useful tool to correct inter-film dosimetric variation for the future clinical film dosimetry verification in very large fields, allowing the optimizations of other parameters.« less

SU-F-T-93: Breast Surface Dose Enhancement Using a Clinical Prone Breast Board

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guerra, M; Jozsef, G

Purpose: The use of specialized patient set-up devices in radiotherapy, such as prone breast boards, may have unwanted dosimetric effects. The goal of this study was to evaluate the effect of a clinically used prone breast board on skin dose due to buildup. Methods: GafChromic film (EBT3) was used for dose measurements on the surface of a solid water phantom shaped to mimic the curvature of the breast. We investigated two setup scenarios: the medial field border placed at the medial edge of the board and 1 cm contralaterally from that edge. A strip of film was taped to themore » medial surface of the phantom. Gantry angles varied from 10 to 30 degrees below the lateral gantry position, representing anterior oblique fields. The measurements were performed with and without the presence of the board; the ratio of their corresponding doses (dose enhancement) was evaluated. Results: For the cases where the field edge is at the edge of the board, the dose enhancement is negligible for all the tested angles. When the field edge is 1 cm inside the board, the maximum surface dose enhancement varies depending on the gantry angle between 2.2 for 30 degrees and 3.2 for 20 degrees. The length on the film at which the presence of the board is detectable (i.e. where there is dose enhancement) is longer for the shallower angles. Conclusion: Even the low-density, thin carbon fiber board with a thin soft foam pad on the top can produce significant dose enhancement on the skin in prone breast treatment due to loss of buildup. However, it happens only when the patient mid-sternum is over the board, i.e. the medial edge of the field traverses through the board and pad. Even then, the effect occurs only at the field edge, i.e. the penumbral region.« less

SU-E-I-06: Measurement of Skin Dose from Dental Cone-Beam CT Scans.

PubMed

Akyalcin, S; English, J; Abramovitch, K; Rong, J

2012-06-01

To directly measure skin dose using point-dosimeters from dental cone-beam CT (CBCT) scans. To compare the results among three different dental CBCT scanners and compare the CBCT results with those from a conventional panoramic and cephalomic dental imaging system. A head anthropomorphic phantom was used with nanoDOT dosimeters attached to specified anatomic landmarks of selected radiosensitive tissues of interest. To ensure reliable measurement results, three dosimeters were used for each location. The phantom was scanned under various modes of operation and scan protocols for typical dental exams on three dental CBCT systems plus a conventional dental imaging system. The Landauer OSL nanoDOT dosimeters were calibrated under the same imaging condition as the head phantom scan protocols, and specifically for each of the imaging systems. Using nanoDOT dosimeters, skin doses at several positions on the surface of an adult head anthropomorphic phantom were measured for clinical dental imaging. The measured skin doses ranged from 0.04 to 4.62mGy depending on dosimeter positions and imaging systems. The highest dose location was at the parotid surface for all three CBCT scanners. The surface doses to the locations of the eyes were ∼4.0mGy, well below the 500mGy threshold for possibly causing cataract development. The results depend on x-ray tube output (kVp and mAs) and also are sensitive to SFOV. Comparing to the conventional dental imaging system operated in panoramic and cephalometric modes, doses from all three CBCT systems were at least an order of magnitude higher. No image artifact was caused by presence of nanoDOT dosimeters in the head phantom images. Direct measurements of skin dose using nanoDOT dosimeters provided accurate skin dose values without any image artifacts. The results of skin dose measurements serve as dose references in guiding future dose optimization efforts in dental CBCT imaging. © 2012 American Association of Physicists in Medicine.

Skin dose in longitudinal and transverse linac-MRIs using Monte Carlo and realistic 3D MRI field models.

PubMed

Keyvanloo, A; Burke, B; Warkentin, B; Tadic, T; Rathee, S; Kirkby, C; Santos, D M; Fallone, B G

2012-10-01

The magnetic fields of linac-MR systems modify the path of contaminant electrons in photon beams, which alters patient skin dose. To accurately quantify the magnitude of changes in skin dose, the authors use Monte Carlo calculations that incorporate realistic 3D magnetic field models of longitudinal and transverse linac-MR systems. Finite element method (FEM) is used to generate complete 3D magnetic field maps for 0.56 T longitudinal and transverse linac-MR magnet assemblies, as well as for representative 0.5 and 1.0 T Helmholtz MRI systems. EGSnrc simulations implementing these 3D magnetic fields are performed. The geometry for the BEAMnrc simulations incorporates the Varian 600C 6 MV linac, magnet poles, the yoke, and the magnetic shields of the linac-MRIs. Resulting phase-space files are used to calculate the central axis percent depth-doses in a water phantom and 2D skin dose distributions for 70 μm entrance and exit layers using DOSXYZnrc. For comparison, skin doses are also calculated in the absence of magnetic field, and using a 1D magnetic field with an unrealistically large fringe field. The effects of photon field size, air gap (longitudinal configuration), and angle of obliquity (transverse configuration) are also investigated. Realistic modeling of the 3D magnetic fields shows that fringe fields decay rapidly and have a very small magnitude at the linac head. As a result, longitudinal linac-MR systems mostly confine contaminant electrons that are generated in the air gap and have an insignificant effect on electrons produced further upstream. The increase in the skin dose for the longitudinal configuration compared to the zero B-field case varies from ∼1% to ∼14% for air gaps of 5-31 cm, respectively. (All dose changes are reported as a % of D(max).) The increase is also field-size dependent, ranging from ∼3% at 20 × 20 cm(2) to ∼11% at 5 × 5 cm(2). The small changes in skin dose are in contrast to significant increases that are calculated for the unrealistic 1D magnetic field. For the transverse configuration, the entrance skin dose is equal or smaller than that of the zero B-field case for perpendicular beams. For a 10 × 10 cm(2) oblique beam the transverse magnetic field decreases the entry skin dose for oblique angles less than ±20° and increases it by no more than 10% for larger angles up to ±45°. The exit skin dose is increased by 42% for a 10 × 10 cm(2) perpendicular beam, but appreciably drops and approaches the zero B-field case for large oblique angles of incidence. For longitudinal linac-MR systems only a small increase in the entrance skin dose is predicted, due to the rapid decay of the realistic magnetic fringe fields. For transverse linac-MR systems, changes to the entrance skin dose are small for most scenarios. For the same geometry, on the exit side a fairly large increase is observed for perpendicular beams, but significantly drops for large oblique angles of incidence. The observed effects on skin dose are not expected to limit the application of linac-MR systems in either the longitudinal or transverse configuration.

Carbon-ion re-irradiation for recurrences after initial treatment of stage I non-small cell lung cancer with carbon-ion radiotherapy.

PubMed

Karube, Masataka; Yamamoto, Naoyoshi; Tsuji, Hiroshi; Kanematsu, Nobuyuki; Nakajima, Mio; Yamashita, Hideomi; Nakagawa, Keiichi; Kamada, Tadashi

2017-10-01

To investigate carbon-ion radiotherapy (CIRT) for in-field recurrence of stage I non-small cell lung cancer (NSCLC) initially treated with CIRT. From January 2007 to March 2014, patients initially treated for stage I NSCLC with CIRT and relapsed in-field were candidates. Overall survival (OS) rate, local control (LC) rate, progressive free survival (PFS) rate, dose to the lungs and skin, and adverse effects were analyzed. Twenty-nine patients were eligible. Median age at re-irradiation was 74years (range 53-90). Median observation period from the first day of re-irradiation was 29months (4-88months). Median prescribed dose was 46.0Gy (RBE) as initial treatment and 66.0Gy (RBE) in 12 fractions as re-irradiation. Two-year OS, LC, and PFS rates after re-irradiation were 69.0% (95% CI: 50.3-83.0), 66.9% (95% CI: 47.5-81.9), and 51.7% (95% CI: 34.1-68.9). Median skin maximum dose was 53.8Gy (RBE) (range 4.4-103.1) and median of mean lung dose was 7.3Gy (RBE) (range 2.6-14.0). There were no severer than grade 2 adverse effects except one (3.4%) grade 3 bacterial pneumonia, which was not considered radiation-induced. CIRT for stage I NSCLC local recurrence is an acceptable definitive re-treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of Gamma Radiation-Induced Biochemical Changes in Skin for Dose Assesment: A Study on Small Experimental Animals.

PubMed

Kumar Soni, Sandeep; Basu, Mitra; Agrawal, Priyanka; Bhatnagar, Aseem; Chhillar, Neelam

2018-05-24

Researchers have been evaluating several approaches to assess acute radiation injury/toxicity markers owing to radiation exposure. Keeping in mind this background, we assumed that whole-body irradiation in single fraction in graded doses can affect the antioxidant profile in skin that could be used as an acute radiation injury/toxicity marker. Sprague-Dawley rats were treated with CO-60 gamma radiation (dose: 1-5 Gy; dose rate: 0.85 Gy/minute). Skin samples were collected (before and after radiation up to 72 hours) and analyzed for glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT), and lipid peroxidation (LPx). Intra-group comparison showed significant differences in GSH, GPx, SOD, and CAT, and they declined in a dose-dependent manner from 1 to 5 Gy (P value0.05). This study suggests that skin antioxidants were sensitive toward radiation even at a low radiation dose, which can be used as a predictor of radiation injury and altered in a dose-dependent manner. These biochemical parameters may have wider application in the evaluation of radiation-induced skin injury and dose assessment. (Disaster Med Public Health Preparedness. 2018;page 1 of 6).

SU-E-T-632: Preliminary Study On Treating Nose Skin Using Energy and Intensity Modulated Electron Beams with Monte Carlo Based Dose Calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, L; Eldib, A; Li, J

Purpose: Uneven nose surfaces and air cavities underneath and the use of bolus present complexity and dose uncertainty when using a single electron energy beam to plan treatments of nose skin with a pencil beam-based planning system. This work demonstrates more accurate dose calculation and more optimal planning using energy and intensity modulated electron radiotherapy (MERT) delivered with a pMLC. Methods: An in-house developed Monte Carlo (MC)-based dose calculation/optimization planning system was employed for treatment planning. Phase space data (6, 9, 12 and 15 MeV) were used as an input source for MC dose calculations for the linac. To reducemore » the scatter-caused penumbra, a short SSD (61 cm) was used. Our previous work demonstrates good agreement in percentage depth dose and off-axis dose between calculations and film measurement for various field sizes. A MERT plan was generated for treating the nose skin using a patient geometry and a dose volume histogram (DVH) was obtained. The work also shows the comparison of 2D dose distributions between a clinically used conventional single electron energy plan and the MERT plan. Results: The MERT plan resulted in improved target dose coverage as compared to the conventional plan, which demonstrated a target dose deficit at the field edge. The conventional plan showed higher dose normal tissue irradiation underneath the nose skin while the MERT plan resulted in improved conformity and thus reduces normal tissue dose. Conclusion: This preliminary work illustrates that MC-based MERT planning is a promising technique in treating nose skin, not only providing more accurate dose calculation, but also offering an improved target dose coverage and conformity. In addition, this technique may eliminate the necessity of bolus, which often produces dose delivery uncertainty due to the air gaps that may exist between the bolus and skin.« less

The maximal cumulative solar UVB dose allowed to maintain healthy and young skin and prevent premature photoaging.

PubMed

Ichihashi, Masamitsu; Ando, Hideya

2014-10-01

The young facial skin of children with a smooth healthy appearance changes over time to photoaged skin having mottled pigmentation, solar lentigines, wrinkles, dry and rough skin, leathery texture, and benign and malignant tumors after exposure to chronic, repeated solar radiation. The first sign of photoaging in Japanese subjects is usually solar lentigines appearing around 20 years of age on the face. Fine wrinkles can then appear after 30 years of age, and benign skin tumors, seborrhoeic keratoses, can occur after 35 years of age in sun-exposed skin. We theoretically calculated the maximal daily exposure time to solar radiation, which could prevent the development of photoaged skin until 60 and 80 years of age, based on published data of personal solar UVB doses in sun-exposed skin. One MED (minimal erythema dose) was determined to be 20 mJ/cm(2) , and 200 MED was used as the average yearly dose of Japanese children. Further, we hypothesized that the annual dose of Japanese adults is the same as that of the children. The cumulative UVB dose at 20 years of age was thus calculated to be 4000 MED, and 22 MED was used as the maximal daily UVB dose based on data measured in Kobe, located in the central area of Japan. We used the solar UVB dose from 10:00 a.m. to 14:00 p.m. which occupies 60% of the total daily UV dose, to obtain the maximal UVB per hour in a day, and calculated the maximal daily UV exposure time that would delay the onset of solar lentigines until 60 or 80 years of age. The mean daily sun exposure time to maintain healthy skin until 80 years of age in the summer was calculated to be 2.54 min (0.14 MED) for unprotected skin and 127 min with the use of a sunscreen of SPF (sun protection factor) of 50. In this study, we did not evaluate the photoaging effect of UVA radiation, but findings of the adverse effects of UVA radiation on the skin have accumulated in the last decade. Therefore, it will be important to estimate the maximal dose of solar UV radiation to retard the onset of photoaging based on an evaluation of both solar UVB and UVA in the future. Finally, we expect that this study may contribute to keeping Japanese and other types of skin young and healthy by limiting the exposure of the skin to solar radiation outdoors during the day. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Estimation Of Organ Doses From Solar Particle Events For Future Space Exploration Missions

NASA Technical Reports Server (NTRS)

Kim, Myung-Hee; Cucinotta, Francis A.

2006-01-01

Radiation protection practices define the effective dose as a weighted sum of equivalent dose over major organ sites for radiation cancer risks. Since a crew personnel dosimeter does not make direct measurement of the effective dose, it has been estimated with skin-dose measurements and radiation transport codes for ISS and STS missions. If sufficient protection is not provided near solar maximum, the radiation risk can be significant due to exposure to sporadic solar particle events (SPEs) as well as to the continuous galactic cosmic radiation (GCR) on future exploratory-class and long-duration missions. For accurate estimates of overall fatal cancer risks from SPEs, the specific doses at various blood forming organs (BFOs) were considered, because proton fluences and doses vary considerably across marrow regions. Previous estimates of BFO doses from SPEs have used an average body-shielding distribution for the bone marrow based on the computerized anatomical man model (CAM). With the development of an 82-point body-shielding distribution at BFOs, the mean and variance of SPE doses in the major active marrow regions (head and neck, chest, abdomen, pelvis and thighs) will be presented. Consideration of the detailed distribution of bone marrow sites is one of many requirements to improve the estimation of effective doses for radiation cancer risks.

Protective effects of fermented honeybush (Cyclopia intermedia) extract (HU-018) against skin aging: a randomized, double-blinded, placebo-controlled study.

PubMed

Choi, Sun Young; Hong, Ji Yeon; Ko, Eun Jung; Kim, Beom Joon; Hong, Sung-Woon; Lim, Mi Hyoung; Yeon, Sung Hum; Son, Rak Ho

2018-02-01

Oxidative stress and photodamage resulting from ultraviolet radiation exposure play key roles in skin aging. Fermented Cyclopia intermedia, which is used to brew honeybush tea, exerts antioxidant and anti-wrinkle effects by inhibiting reactive oxygen species production and downregulating matrix metalloproteinase activity. This randomized, double-blinded, placebo-controlled study aimed to evaluate the efficacy and safety of fermented honeybush (Cyclopia intermedia) extract (HU-018) for skin rejuvenation. 120 Korean subjects with crow's feet wrinkles were randomized to receive either low-dose extract (400 mg/day), high-dose extract (800 mg/day), or placebo (negative control, only dextran) for 12 weeks. Wrinkles were evaluated using JANUS ® and PRIMO pico ® . Skin elasticity, hydration and transepidermal water loss were measured. Global skin wrinkle grade was significantly improved in both low-dose and high-dose groups compared to placebo group, as well as for skin hydration and elasticity. Both the low- and high-dose groups showed significantly decreased TEWL compared to the placebo group. There were no adverse effects during the entire study period. Our data indicate that HU-018 is effective for improving skin wrinkles, elasticity, and hydration. Therefore, daily supplementation with fermented honeybush could be helpful for protecting against skin aging.

Radiation exposure of contrast-enhanced spectral mammography compared with full-field digital mammography.

PubMed

Jeukens, Cécile R L P N; Lalji, Ulrich C; Meijer, Eduard; Bakija, Betina; Theunissen, Robin; Wildberger, Joachim E; Lobbes, Marc B I

2014-10-01

Contrast-enhanced spectral mammography (CESM) shows promising initial results but comes at the cost of increased dose as compared with full-field digital mammography (FFDM). We aimed to quantitatively assess the dose increase of CESM in comparison with FFDM. Radiation exposure-related data (such as kilovoltage, compressed breast thickness, glandularity, entrance skin air kerma (ESAK), and average glandular dose (AGD) were retrieved for 47 CESM and 715 FFDM patients. All examinations were performed on 1 mammography unit. Radiation dose values reported by the unit were validated by phantom measurements. Descriptive statistics of the patient data were generated using a statistical software package. Dose values reported by the mammography unit were in good qualitative agreement with those of phantom measurements. Mean ESAK was 10.5 mGy for a CESM exposure and 7.46 mGy for an FFDM exposure. Mean AGD for a CESM exposure was 2.80 mGy and 1.55 mGy for an FFDM exposure. Compared with our institutional FFDM, the AGD of a single CESM exposure is increased by 1.25 mGy (+81%), whereas ESAK is increased by 3.07 mGy (+41%). Dose values of both techniques meet the recommendations for maximum dose in mammography.

The physiological and phenotypic determinants of human tanning measured as change in skin colour following a single dose of ultraviolet B radiation.

PubMed

Wong, Terence H; Jackson, Ian J; Rees, Jonathan L

2010-07-01

Experimental study of the in vivo kinetics of tanning in human skin has been limited by the difficulties in measuring changes in melanin pigmentation independent of the ultravioletinduced changes in erythema. The present study attempted to experimentally circumvent this issue. We have studied erythemal and tanning responses following a single exposure to a range of doses of ultraviolet B irradiation on the buttock and the lower back in 98 subjects. Erythema was assessed using reflectance techniques at 24 h and tanning measured as the L* spectrophotometric score at 7 days following noradrenaline iontophoresis. We show that dose (P < 0.0001), body site (P < 0.0001), skin colour (P < 0.0001), ancestry (P = 0.0074), phototype (P = 0.0019) and sex (P = 0.04) are all independent predictors of erythema. Quantitative estimates of the effects of these variables are reported, but the effects of ancestry and phototype do not appear solely explainable in terms of L* score. Dose (P < 0.0001), body site (P < 0.0001) and skin colour (P = 0.0365) or, as an alternative to skin colour, skin type (P = 0.0193) predict tanning, with those with lighter skin tanning slightly more to a defined UVB dose. If erythema is factored into the regression, then only dose and body site remain significant predictors of tanning: therefore neither phototype nor pigmentary factors, such as baseline skin colour, or eye or hair colour, predict change in skin colour to a unit erythemal response.

SU-E-CAMPUS-I-04: Automatic Skin-Dose Mapping for An Angiographic System with a Region-Of-Interest, High-Resolution Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vijayan, S; Rana, V; Setlur Nagesh, S

2014-06-15

Purpose: Our real-time skin dose tracking system (DTS) has been upgraded to monitor dose for the micro-angiographic fluoroscope (MAF), a high-resolution, small field-of-view x-ray detector. Methods: The MAF has been mounted on a changer on a clinical C-Arm gantry so it can be used interchangeably with the standard flat-panel detector (FPD) during neuro-interventional procedures when high resolution is needed in a region-of-interest. To monitor patient skin dose when using the MAF, our DTS has been modified to automatically account for the change in scatter for the very small MAF FOV and to provide separated dose distributions for each detector. Themore » DTS is able to provide a color-coded mapping of the cumulative skin dose on a 3D graphic model of the patient. To determine the correct entrance skin exposure to be applied by the DTS, a correction factor was determined by measuring the exposure at the entrance surface of a skull phantom with an ionization chamber as a function of entrance beam size for various beam filters and kVps. Entrance exposure measurements included primary radiation, patient backscatter and table forward scatter. To allow separation of the dose from each detector, a parameter log is kept that allows a replay of the procedure exposure events and recalculation of the dose components.The graphic display can then be constructed showing the dose distribution from the MAF and FPD separately or together. Results: The DTS is able to provide separate displays of dose for the MAF and FPD with field-size specific scatter corrections. These measured corrections change from about 49% down to 10% when changing from the FPD to the MAF. Conclusion: The upgraded DTS allows identification of the patient skin dose delivered when using each detector in order to achieve improved dose management as well as to facilitate peak skin-dose reduction through dose spreading. Research supported in part by Toshiba Medical Systems Corporation and NIH Grants R43FD0158401, R44FD0158402 and R01EB002873.« less

In vitro dermal absorption of di(2-ethylhexyl) adipate (DEHA) in a roll-on deodorant using human skin.

PubMed

Zhou, Simon Ningsun; Moody, Richard P; Aikawa, Bio; Yip, Anna; Wang, Bing; Zhu, Jiping

2013-01-01

In vitro dermal absorption experiments were conducted using a roll-on deodorant that contains 1.56% di(2-ethylhexyl) adipate (DEHA), a plasticizer widely used in consumer products. Human skin specimens were fitted in Bronaugh flow-through Teflon diffusion cells. The diffusion cells were maintained at 32 °C to reflect the skin temperature. Two amounts (low dose: 5 mg of the product; high dose: 100 mg) were applied, in triplicate, each on four different human skins. DEHA was determined in the receiver solution at 6-h intervals, using headspace solid-phase microextraction gas chromatography-mass spectrometry (GC-MS). After 24 h, the experiment was terminated and masses of DEHA in the skin depot, skin wash, and upper and lower chambers of the diffusion cell were determined. A significant portion of applied DEHA, 28% in the low amount application and 34% in the high one, was found in the skin depot. In comparison, only 0.04% and 0.002% of applied DEHA were found in the receiver solutions for the low and high doses, respectively. Under our experimental conditions, an apparent steady-state flux of low DEHA mass penetrating from skin into the receiver solution was observed with a penetration rate of 2.2 ng/cm(2)/h for both the low and high doses. The average mass recovery was 81% for the low dose application and 56% for the high dose.

Can we use the equivalent sphere model to approximate organ doses in space radiation environments?

NASA Astrophysics Data System (ADS)

Lin, Zi-Wei

For space radiation protection one often calculates the dose or dose equivalent in blood forming organs (BFO). It has been customary to use a 5cm equivalent sphere to approximate the BFO dose. However, previous studies have concluded that a 5cm sphere gives a very different dose from the exact BFO dose. One study concludes that a 9cm sphere is a reasonable approximation for the BFO dose in solar particle event (SPE) environments. In this study we investigate the reason behind these observations and extend earlier studies by studying whether BFO, eyes or the skin can be approximated by the equivalent sphere model in different space radiation environments such as solar particle events and galactic cosmic ray (GCR) environments. We take the thickness distribution functions of the organs from the CAM (Computerized Anatomical Man) model, then use a deterministic radiation transport to calculate organ doses in different space radiation environments. The organ doses have been evaluated with a water or aluminum shielding from 0 to 20 g/cm2. We then compare these exact doses with results from the equivalent sphere model and determine in which cases and at what radius parameters the equivalent sphere model is a reasonable approximation. Furthermore, we propose to use a modified equivalent sphere model with two radius parameters to represent the skin or eyes. For solar particle events, we find that the radius parameters for the organ dose equivalent increase significantly with the shielding thickness, and the model works marginally for BFO but is unacceptable for eyes or the skin. For galactic cosmic rays environments, the equivalent sphere model with one organ-specific radius parameter works well for the BFO dose equivalent, marginally well for the BFO dose and the dose equivalent of eyes or the skin, but is unacceptable for the dose of eyes or the skin. The BFO radius parameters are found to be significantly larger than 5 cm in all cases, consistent with the conclusion of an earlier study. The radius parameters for the dose equivalent in GCR environments are approximately between 10 and 11 cm for the BFO, 3.7 to 4.8 cm for eyes, and 3.5 to 5.6 cm for the skin; while the radius parameters are between 10 and 13 cm for the BFO dose. In the proposed modified equivalent sphere model, the range of each of the two radius parameters for the skin (or eyes) is much tighter than that in the equivalent sphere model with one radius parameter. Our results thus show that the equivalent sphere model works better in galactic cosmic rays environments than in solar particle events. The model works well or marginally well for BFO but usually does not work for eyes or the skin. A modified model with two radius parameters works much better in approximating the dose and dose equivalent in eyes or the skin.

Enhancement of Skin Permeation and Skin Immunization of Ovalbumin Antigen via Microneedles.

PubMed

Pamornpathomkul, Boonnada; Rojanarata, Theerasak; Opanasopit, Praneet; Ngawhirunpat, Tanasait

2017-10-01

The purpose of this study was to evaluate the use of different types of microneedles and doses of ovalbumin antigen for in vitro skin permeation and in vivo immunization. In vitro skin permeation experiments and confocal laser scanning microscopy revealed that hollow microneedles had a superior enhancing effect on skin permeation compared with a solid microneedle patch and untreated skin by efficiently delivering ovalbumin-fluorescein conjugate into the deep skin layers. The flux and cumulative amount of ovalbumin-fluorescein conjugate at 8 h after administering with various conditions could be ranked as follows: hollow MN; high dose > medium dose > low dose > MN patch; high dose > medium dose > low dose > untreated skin; high dose > medium dose > low dose > without ovalbumin-fluorescein conjugate. As the dose of ovalbumin-fluorescein conjugate was increased to 500 μg, the antigen accumulated in the skin to a greater extent, as evidenced by the increasing green fluorescence intensity. When the hollow microneedle was used for the delivery of ovalbumin into the skin of mice, it was capable of inducing a stronger immunoglobulin G immune response than conventional subcutaneous injection at the same antigen dose. Immunoglobulin G levels in the hollow MN group were 5.7, 11.6, and 13.3 times higher than those of the subcutaneous injection group for low, medium, and high doses, respectively. Furthermore, the mice immunized using the hollow microneedle showed no signs of skin infection or pinpoint bleeding. The results suggest that the hollow MN is an efficient device for delivering the optimal dose of antigen via the skin for successful immunization.

Pigmentation after single and multiple UV-exposures depending on UV-spectrum.

PubMed

Ravnbak, M H; Wulf, H C

2007-04-01

Minimal pigmentation dose (MMD) after a single UV-exposure is well investigated. Whereas only few studies have established MMD after multiple UV-exposures and mainly in fair-skinned persons. The purpose of this study was to establish MMD 1 week after, respectively, one and five UV-exposures in volunteers with a large variation in constitutive pigmentation. A total of 52 volunteers (skin Types II-V) had skin pigmentation quantified by reflectance spectroscopy. They were UV-exposed on the back for 1 and 5 days using a Solar Simulator, narrowband UVB, broadband UVA and UVA1. For all sources a higher dose was needed the more pigmented the skin, except for UVA1. After one UV-exposure, we found a significant positive linear correlation between UV-dose to one MMD, skin type and pre-exposure skin pigmentation. After five UV-exposures the positive linear correlation between UV-dose and MMD and skin type was only significant for narrow band UVB, pre-exposure skin pigmentation was significant also for Solar Simulator. For UVA and particularly UVA1 the MMD was independent of pre-exposure pigmentation. The number of SED to MMD is therefore almost the same for very fair-skinned and dark-skinned persons. Pre-exposure pigmentation was clearly more predictive of MMD than skin type. 50% of MMD equals a pigmentation increase of 1%. The shorter the wavelengths the higher the SED to produce MMD. Solar was the least melanogenic and UVA1 the most melanogenic. For the UVB-sources a higher dose was needed the more pigmented the skin. For UVA the MMD was independent of pre-exposure pigmentation.

Effects of hypervitaminosis of vitamin B3 on silkworm biology.

PubMed

Etebari, Kayvan; Matindoost, Leila

2004-12-01

A high-dose of vitamin B(3) in silkworm diet interrupts larval feeding and normal growth. High mortality of larvae occurs during molting and they cannot complete this process normally. Also the larvae exhibit nicotinamide hypervitaminosis symptoms such as immobility, dyspepsia, darkening of the skin, inability to excrete normally, exerting brownish fluid from anus and swelling of rectal muscles. Maximum larval weights in 1, 2 and 3 g/l treatments were 2.9, 1.6 and 1.2 g respectively, while maximum larval weight in the control was 5.6 g. Larval stage compared to control had increased 18, 26 and 31 days respectively. The concentration increase of uric acid in haemolymph demonstrates the hyperuricemia, while other measured biochemical compounds show significant decrease; sodium and potassium did not change significantly.

PCC-FISH in skin fibroblasts for local dose assessment: biodosimetric analysis of a victim of the Georgian radiological accident.

PubMed

Pouget, J-P; Laurent, C; Delbos, M; Benderitter, M; Clairand, I; Trompier, F; Stéphanazzi, J; Carsin, H; Lambert, F; Voisin, P; Gourmelon, P

2004-10-01

We propose a new method of biodosimetry that could be applied in cases of localized irradiation. The approach is based on excess chromosome segments determination by the PCC-FISH technique in fibroblasts isolated from skin biopsy. Typically, 0 to 10 Gy ex vivo gamma-irradiated human skin biopsies were dissociated and fibroblasts were isolated and grown for several days. Cells next underwent PCC-FISH painting of whole chromosome 4, and the number of excess chromosome segments per metaphase was determined. An ex vivo reference curve correlating the number of excess chromosome segments per metaphase to the radiation dose was established and used to assess the dose delivered to the skin of one of the victims of the radiological accident that occurred at Lia in Georgia in December 2001. Specifically, the victim suffering from moist desquamation underwent skin excision in Hospital Percy (France). Measurement of excess chromosome segments per metaphase was done in fibroblasts isolated and grown from removed wounded skin and subsequent conversion to radiation doses was performed. The radiation dose map obtained was shown to be in accordance with clinical data and physical dosimetry as well as with conventional biodosimetry. These results demonstrated that PCC-FISH painting applied to skin fibroblasts may be a suitable technique for dose estimation. To assess its worth, this approach needs to be extended to future accidents involving localized radiation exposure.

Evaluation of clinical use of OneDose™ metal oxide semiconductor field-effect transistor detectors compared to thermoluminescent dosimeters to measure skin dose for adult patients with acute lymphoblastic leukemia

PubMed Central

Al-Mohammed, Huda Ibrahim

2011-01-01

Background: Total body irradiation is a protocol used to treat acute lymphoblastic leukemia in patients prior to their bone marrow transplant. It involves the treatment of the whole body using a large radiation field with extended source-skin distance. Therefore, it is important to measure and monitor the skin dose during the treatment. Thermoluminescent dosimeters (TLDs) and the OneDose™ metal oxide semiconductor field effect transistor (MOSFET) detectors are used during treatment delivery to measure the radiation dose and compare it with the target prescribed dose. Aims: The primary goal of this study was to measure the variation of skin dose using OneDose MOSFET detectors and TLD detectors, and compare the results with the target prescribed dose. The secondary aim was to evaluate the simplicity of use and determine if one system was superior to the other in clinical use. Material and Methods: The measurements involved twelve adult patients diagnosed with acute lymphoblastic leukemia. TLD and OneDose MOSFET dosimetry were performed at ten different anatomical sites of each patient. Results: The results showed that there was a variation between skin dose measured with OneDose MOSFET detectors and TLD in all patients. However, the variation was not significant. Furthermore, the results showed for every anatomical site there was no significant different between the prescribed dose and the dose measured by either TLD or OneDose MOSFET detectors. Conclusion: There were no significant differences between the OneDose MOSFET and TLDs in comparison to the target prescribed dose. However, OneDose MOSFET detectors give a direct read-out immediately after the treatment, and their simplicity of use to compare with TLD detectors may make them preferred for clinical use. PMID:22171243

850nm light-emitting-diode phototherapy plus low-dose tacrolimus (FK-506) as combination therapy in the treatment of Dermatophagoides farinae-induced atopic dermatitis-like skin lesions in NC/Nga mice.

PubMed

Kim, Chang-Hyun; Cheong, Kyung Ah; Lee, Ai-Young

2013-11-01

Light emitting diode (LED) phototherapy is an effective alternative for the treatment of inflammatory skin disorders. Tacrolimus (FK-506) is a potent immunomodulating agent, which has been used to treat AD. Combination therapy is often used in the treatment of AD to improve therapeutic efficacy or to reduce the dose of each drug. To investigate the therapeutic efficacy of monotherapy with either 850nm LED phototherapy or low-dose FK-506, and combination therapy in Dermatophagoides farina (Df)-induced AD-like skin lesions in NC/Nga mice. The Df-induced NC/Nga mice with a clinical score of 7 were used for treatment with LED (10 and 25J/cm(2)) alone, low-dose FK-506 (1mg/kg) or in combination. The synergistic effects of combined therapy were evaluated by dermatitis scores, skin histology, skin barrier function, and immunological parameters, such as IgE, NO, Th2-mediated cytokines and chemokines. Combination therapy with 850nm (25J/cm(2)) LED and low-dose FK-506 showed a significant reduction in the severity of skin lesions. Combined therapy decreased in the serum level of IgE, NO, and in the splenic level of Th2-mediated cytokines and chemokines. Combination therapy significantly also reduced the inflammatory cellular infiltrate into the skin lesions. Moreover, combination therapy led to recovery of skin barrier function in the skin lesions. The use of combination of LED phototherapy and low-dose immunosuppressant improved Df-induced AD-like skin lesions in an NC/Nga mouse model by dominantly reducing IgE, NO, suppressing Th2-mediated immune responses, and inhibiting inflammatory cells, as well as improving skin barrier function. Copyright © 2013 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

Biodosimetric quantification of short-term synchrotron microbeam versus broad-beam radiation damage to mouse skin using a dermatopathological scoring system

PubMed Central

Priyadarshika, R C U; Crosbie, J C; Kumar, B; Rogers, P A W

2011-01-01

Objectives Microbeam radiotherapy (MRT) with wafers of microscopically narrow, synchrotron generated X-rays is being used for pre-clinical cancer trials in animal models. It has been shown that high dose MRT can be effective at destroying tumours in animal models, while causing unexpectedly little damage to normal tissue. The aim of this study was to use a dermatopathological scoring system to quantify and compare the acute biological response of normal mouse skin with microplanar and broad-beam (BB) radiation as a basis for biological dosimetry. Method The skin flaps of three groups of mice were irradiated with high entrance doses (200 Gy, 400 Gy and 800 Gy) of MRT and BB and low dose BB (11 Gy, 22 Gy and 44 Gy). The mice were culled at different time-points post-irradiation. Skin sections were evaluated histologically using the following parameters: epidermal cell death, nuclear enlargement, spongiosis, hair follicle damage and dermal inflammation. The fields of irradiation were identified by γH2AX-positive immunostaining. Results The acute radiation damage in skin from high dose MRT was significantly lower than from high dose BB and, importantly, similar to low dose BB. Conclusion The integrated MRT dose was more relevant than the peak or valley dose when comparing with BB fields. In MRT-treated skin, the apoptotic cells of epidermis and hair follicles were not confined to the microbeam paths. PMID:21849367

Pharmacokinetics of testosterone cream applied to scrotal skin.

PubMed

Iyer, R; Mok, S F; Savkovic, S; Turner, L; Fraser, G; Desai, R; Jayadev, V; Conway, A J; Handelsman, D J

2017-07-01

Scrotal skin is thin and has high steroid permeability, but the pharmacokinetics of testosterone via the scrotal skin route has not been studied in detail. The aim of this study was to define the pharmacokinetics of testosterone delivered via the scrotal skin route. The study was a single-center, three-phase cross-over pharmacokinetic study of three single doses (12.5, 25, 50 mg) of testosterone cream administered in random sequence on different days with at least 2 days between doses to healthy eugonadal volunteers with endogenous testosterone suppressed by administration of nandrolone decanoate. Serum testosterone, DHT and estradiol concentrations were measured by liquid chromatograpy, mass spectrometry in extracts of serum taken before and for 16 h after administration of each of the three doses of testosterone cream to the scrotal skin. Testosterone administration onto the scrotal skin produced a swift (peak 1.9-2.8 h), dose-dependent (p < 0.0001) increase in serum testosterone with the 25 mg dose maintaining physiological levels for 16 h. Serum DHT displayed a time- (p < 0.0001), but not dose-dependent, increase in concentration reaching a peak concentration of 1.2 ng/mL (4.1 nm) at 4.9 h which was delayed by 2 h after peak serum testosterone. There were no significant changes in serum estradiol over time after testosterone administration. We conclude that testosterone administration to scrotal skin is well tolerated and produces dose-dependent peak serum testosterone concentration with a much lower dose relative to the non-scrotal transdermal route. © 2017 American Society of Andrology and European Academy of Andrology.

Immediate hypersensitivity to iodinated contrast media: diagnostic accuracy of skin tests and intravenous provocation test with low dose.

PubMed

Sesé, L; Gaouar, H; Autegarden, J-E; Alari, A; Amsler, E; Vial-Dupuy, A; Pecquet, C; Francès, C; Soria, A

2016-03-01

The diagnosis of HSR to iodinated contrast media (ICM) is challenging based on clinical history and skin tests. This study evaluates the negative predictive value (NPV) of skin tests and intravenous provocation test (IPT) with low-dose ICM in patients with suspected immediate hypersensitivity reaction (HSR) to ICM. Thirty-seven patients with suspected immediate hypersensitivity reaction to ICM were included retrospectively. Skin tests and a single-blind placebo-controlled intravenous provocation test (IPT) with low-dose iodinated contrast media (ICM) were performed. Skin tests with ICM were positive in five cases (one skin prick test and five intradermal test). Thirty-six patients were challenged successfully by IPT, and only one patient had a positive challenge result, with a grade I reaction by the Ring and Messmer classification. Ten of 23 patients followed up by telephone were re-exposed to a negative tested ICM during radiologic examination; two experienced a grade I immediate reaction. For immediate hypersensitivity reaction to ICM, the NPV for skin tests and IPT with low dose was 80% (95% CI 44-97%). © 2016 John Wiley & Sons Ltd.

Characterization of differences in calculated and actual measured skin doses to canine limbs during stereotactic radiosurgery using Gafchromic film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walters, Jerri; Colorado State University, Fort Collins, CO; Ryan, Stewart

Accurate calculation of absorbed dose to the skin, especially the superficial and radiosensitive basal cell layer, is difficult for many reasons including, but not limited to, the build-up effect of megavoltage photons, tangential beam effects, mixed energy scatter from support devices, and dose interpolation caused by a finite resolution calculation matrix. Stereotactic body radiotherapy (SBRT) has been developed as an alternative limb salvage treatment option at Colorado State University Veterinary Teaching Hospital for dogs with extremity bone tumors. Optimal dose delivery to the tumor during SBRT treatment can be limited by uncertainty in skin dose calculation. The aim of thismore » study was to characterize the difference between measured and calculated radiation dose by the Varian Eclipse (Varian Medical Systems, Palo Alto, CA) AAA treatment planning algorithm (for 1-mm, 2-mm, and 5-mm calculation voxel dimensions) as a function of distance from the skin surface. The study used Gafchromic EBT film (International Specialty Products, Wayne, NJ), FilmQA analysis software, a limb phantom constructed from plastic water Trade-Mark-Sign (fluke Biomedical, Everett, WA) and a canine cadaver forelimb. The limb phantom was exposed to 6-MV treatments consisting of a single-beam, a pair of parallel opposed beams, and a 7-beam coplanar treatment plan. The canine forelimb was exposed to the 7-beam coplanar plan. Radiation dose to the forelimb skin at the surface and at depths of 1.65 mm and 1.35 mm below the skin surface were also measured with the Gafchromic film. The calculation algorithm estimated the dose well at depths beyond buildup for all calculation voxel sizes. The calculation algorithm underestimated the dose in portions of the buildup region of tissue for all comparisons, with the most significant differences observed in the 5-mm calculation voxel and the least difference in the 1-mm voxel. Results indicate a significant difference between measured and calculated data extending to average depths of 2.5 mm, 3.4 mm, and 10 mm for the 1-mm, 2-mm, and 5-mm dimension calculation matrices, respectively. These results emphasize the importance of selecting as small a treatment planning software calculation matrix dimension as is practically possible and of taking a conservative approach for skin treatment planning objectives. One suggested conservative approach is accomplished by defining the skin organ as the outermost 2-3 mm of the body such that the high dose tail of the skin organ dose-volume histogram curve represents dose on the deep side of the skin where the algorithm is more accurate.« less

Development, validation and testing of a skin sampling method for assessment of metal exposure.

PubMed

Erfani, Behnaz; Midander, Klara; Lidén, Carola; Julander, Anneli

2017-07-01

Nickel, cobalt and chromium are frequent skin sensitizers. Skin exposure results in eczema in sensitized individuals, the risk being related to the skin dose. To develop a self-sampling method for quantification of skin exposure to metals, to validate the method, and to assess its feasibility. Defined metal doses (0.01-5 µg) were applied to the fingers of 5 participants. Skin areas (2 cm 2 ) were sampled with 1% HNO 3 , either as 0.1 ml on a swab, or as 0.5 ml on a wipe. Furthermore, 17 participants performed self-sampling by swab after 2 h of leisure activity. Samples were extracted in 1% HNO 3 and analysed by inductively coupled plasma mass spectrometry. The sampling efficiency by swab was 46%, as compared with 93% for acid wipe sampling, for all tested doses. Most metal from the skin dose was detected in the first swab (33-43%). Despite lower sampling efficiency by swab, skin doses of metals following 2 h of leisure activity without hand washing were quantified in all participants, and ranged from 0.0016 to 0.15 µg/cm 2 , from 0.00014 to -0.0020 µg/cm 2 and from 0.00048 to -0.027 µg/cm 2 for nickel, cobalt, and chromium, respectively. The results indicate a future potential of skin sampling by swab to detect and monitor metals on skin by self-sampling. This will contribute to better knowledge of metal skin exposure among dermatitis patients, workers, and the general population. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

In Vitro Skin Penetration of Petrolatum and Soybean Oil and Effects of Glyceryl Monooleate.

PubMed

Intarakumhaeng, Rattikorn; Shi, Zhanquan; Wanasathop, Apipa; Stella, Q Ching; Wei, Karl S; Styczynski, P B; Li, Chuiying; Smith, Edward D; Li, S Kevin

2018-06-06

Petrolatum and soybean oil are common ingredients incorporated in topical skin formulations for skin protection and moisturization. However, the stratum corneum (SC) penetration kinetics of these two cosmetic ingredients has not been systematically studied. Glyceryl monooleate (GlyMOle) has been shown to enhance skin penetration of various compounds. It was hypothesized that GlyMOle could enhance skin penetration of petrolatum and soybean oil. The present study aimed to examine the in vitro skin penetration of petrolatum and soybean oil in the presence or absence of GlyMOle. Skin permeation experiments were conducted using the in vitro Franz diffusion cell model with split-thickness human skin and human epidermal membrane (HEM). The effect of permeant dose and the kinetics of permeant penetration were examined with and without GlyMOle in vitro. Petrolatum and soybean oil were found to permeate across HEM, and no effect of GlyMOle on skin permeation into the receptor chamber was observed. GlyMOle enhanced the penetration of petrolatum into the split-thickness skin at 50 μg dose (petrolatum:GlyMOle, 49:1, w/w). However, no effect of GlyMOle on petrolatum penetration was observed at 200 μg dose (petrolatum:GlyMOle, 49:1, w/w), indicating a dose-dependent effect. GlyMOle at the level used in the study did not enhance the penetration of soybean oil with 50 and 200 μg doses at any time points. GlyMOle was a skin penetration enhancer for petrolatum under the in vitro conditions identified in the present study. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

The influence of intrinsic sympathomimetic activity and beta-1 receptor selectivity on the recovery of finger skin temperature after finger cooling in normotensive subjects.

PubMed

Lenders, J W; Salemans, J; de Boo, T; Lemmens, W A; Thien, T; van't Laar, A

1986-03-01

A double-blind randomized study was designed to investigate differences in the recovery of finger skin temperature after finger cooling during dosing with placebo or one of four beta-blockers: propranolol, atenolol, pindolol, and acebutolol. In 11 normotensive nonsmoking subjects, finger skin temperature was measured with a thermocouple before and 20 minutes after immersion of one hand in a water bath at 16 degrees C. This finger cooling test caused no significant changes in systemic hemodynamics such as arterial blood pressure, heart rate, and forearm blood flow. The recovery of finger skin temperature during propranolol dosing was better than that during pindolol and atenolol dosing. There were no differences between the recoveries of skin temperature during pindolol, atenolol, and acebutolol dosing. Thus we could demonstrate no favorable effect of intrinsic sympathomimetic activity or beta 1-selectivity on the recovery of finger skin temperature after finger cooling.

NOTE: Dose area product evaluations with Gafchromic® XR-R films and a flat-bed scanner

NASA Astrophysics Data System (ADS)

Rampado, O.; Garelli, E.; Deagostini, S.; Ropolo, R.

2006-12-01

Gafchromic® XR-R films are a useful tool to evaluate entrance skin dose in interventional radiology. Another dosimetric quantity of interest in diagnostic and interventional radiology is the dose area product (DAP). In this study, a method to evaluate DAP using Gafchromic® XR-R films and a flat-bed scanner was developed and tested. Film samples were exposed to an x-ray beam of 80 kVp over a dose range of 0 10 Gy. DAP measurements with films were obtained from the digitalization of a film sample positioned over the x-ray beam window during the exposure. DAP values obtained with this method were compared for 23 cardiological interventional procedures with DAP values displayed by the equipment. The overall one-sigma dose measurement uncertainty depended on the absorbed dose, with values below 6% for doses above 1 Gy. A maximum discrepancy of 16% was found, which is of the order of the differences in the DAP measurements that may occur with different calibration procedures. Based on the results presented, after an accurate calibration procedure and a thorough inspection of the relationship between the actual dose and the direct measured quantity (net optical density or net pixel value variation), Gafchromic® XR-R films can be used to assess the DAP.

Analysis of the Potential Topical Anti-Inflammatory Activity of Averrhoa carambola L. in Mice

PubMed Central

Cabrini, Daniela Almeida; Moresco, Henrique Hunger; Imazu, Priscila; da Silva, Cíntia Delai; Pietrovski, Evelise Fernandes; Mendes, Daniel Augusto Gasparin Bueno; Prudente, Arthur da Silveira; Pizzolatti, Moacir Geraldo; Brighente, Inês Maria Costa; Otuki, Michel Fleith

2011-01-01

Inflammatory skin disorders, such as psoriasis and atopic dermatitis, are very common in the population; however, the treatments currently available are not well tolerated and are often ineffective. Averrhoa carambola L. (Oxalidaceae) is an Asian tree that has been used in traditional folk medicine in the treatment of several skin disorders. The present study evaluates the topical anti-inflammatory effects of the crude ethanolic extract of A. carambola leaves, its hexane, ethyl acetate, and butanol fractions and two isolated flavonoids on skin inflammation. Anti-inflammatory activity was measured using a croton oil-induced ear edema model of inflammation in mice. Topically applied ethanolic extract reduced edema in a dose-dependent manner, resulting in a maximum inhibition of 73 ± 3% and an ID50 value of 0.05 (range: 0.02–0.13) mg/ear. Myeloperoxidase (MPO) activity was also inhibited by the extract, resulting in a maximum inhibition of 60 ± 6% (0.6 mg/ear). All of the fractions tested caused inhibition of edema formation and of MPO activity. Treatment with the ethyl acetate fraction was the most effective, resulting in inhibition levels of 75 ± 5 and 54 ± 8% for edema formation and MPO activity, respectively. However, treatment of mice with isolated compounds [apigenin-6-C-β-l-fucopyranoside and apigenin-6-C-(2″-O-α-l-rhamnopyranosyl)-β-l-fucopyranoside] did not yield successful results. Apigenin-6-C-(2″-O-α-l-rhamnopyranosyl)-β-l-fucopyranoside caused only a mild reduction in edema formation (28 ± 11%). Taken together, these preliminary results support the popular use of A. carambola as an anti-inflammatory agent and open up new possibilities for its use in skin disorders. PMID:21785638

Analysis of the Potential Topical Anti-Inflammatory Activity of Averrhoa carambola L. in Mice.

PubMed

Cabrini, Daniela Almeida; Moresco, Henrique Hunger; Imazu, Priscila; da Silva, Cíntia Delai; Pietrovski, Evelise Fernandes; Mendes, Daniel Augusto Gasparin Bueno; da Silveira Prudente, Arthur; Pizzolatti, Moacir Geraldo; Brighente, Inês Maria Costa; Otuki, Michel Fleith

2011-01-01

Inflammatory skin disorders, such as psoriasis and atopic dermatitis, are very common in the population; however, the treatments currently available are not well tolerated and are often ineffective. Averrhoa carambola L. (Oxalidaceae) is an Asian tree that has been used in traditional folk medicine in the treatment of several skin disorders. The present study evaluates the topical anti-inflammatory effects of the crude ethanolic extract of A. carambola leaves, its hexane, ethyl acetate, and butanol fractions and two isolated flavonoids on skin inflammation. Anti-inflammatory activity was measured using a croton oil-induced ear edema model of inflammation in mice. Topically applied ethanolic extract reduced edema in a dose-dependent manner, resulting in a maximum inhibition of 73 ± 3% and an ID(50) value of 0.05 (range: 0.02-0.13) mg/ear. Myeloperoxidase (MPO) activity was also inhibited by the extract, resulting in a maximum inhibition of 60 ± 6% (0.6 mg/ear). All of the fractions tested caused inhibition of edema formation and of MPO activity. Treatment with the ethyl acetate fraction was the most effective, resulting in inhibition levels of 75 ± 5 and 54 ± 8% for edema formation and MPO activity, respectively. However, treatment of mice with isolated compounds [apigenin-6-C-β-l-fucopyranoside and apigenin-6-C-(2″-O-α-l-rhamnopyranosyl)-β-l-fucopyranoside] did not yield successful results. Apigenin-6-C-(2″-O-α-l-rhamnopyranosyl)-β-l-fucopyranoside caused only a mild reduction in edema formation (28 ± 11%). Taken together, these preliminary results support the popular use of A. carambola as an anti-inflammatory agent and open up new possibilities for its use in skin disorders.

Topical Application of Aloe vera Accelerated Wound Healing, Modeling, and Remodeling: An Experimental Study.

PubMed

Oryan, Ahmad; Mohammadalipour, Adel; Moshiri, Ali; Tabandeh, Mohammad Reza

2016-01-01

Treatment of large wounds is technically demanding and several attempts have been taken to improve wound healing. Aloe vera has been shown to have some beneficial roles on wound healing but its mechanism on various stages of the healing process is not clear. This study was designed to investigate the effect of topical application of A. vera on cutaneous wound healing in rats. A rectangular 2 × 2-cm cutaneous wound was created in the dorsum back of rats. The animals were randomly divided into 3 groups of control (n = 20), low-dose (n = 20), and high-dose (n = 20) A. vera. The control and treated animals were treated daily with topical application of saline, low-dose (25 mg/mL), and high-dose (50 mg/mL) A. vera gel, up to 10 days, respectively. The wound surface, wound contraction, and epithelialization were monitored. In each group, the animals were euthanized at 10 (n = 5), 20 (n = 5), and 30 (n = 10) days post injury (DPI). At 10, 20, and 30 DPI, the skin samples were used for histopathological and biochemical investigations; and at 30 DPI, the skin samples were also subjected for biomechanical studies. Aloe vera modulated the inflammation, increased wound contraction and epithelialization, decreased scar tissue size, and increased alignment and organization of the regenerated scar tissue. A dose-dependent increase in the tissue level of dry matter, collagen, and glycosaminoglycans' content was seen in the treated lesions, compared to the controls. The treated lesions also demonstrated greater maximum load, ultimate strength, and modulus of elasticity compared to the control ones (P < 0.05). Topical application of A. vera improved the biochemical, morphological, and biomechanical characteristics of the healing cutaneous wounds in rats. This treatment option may be valuable in clinical practice.

Sunburn risk among children and outdoor workers in South Africa and Reunion Island coastal sites.

PubMed

Wright, Caradee Y; Brogniez, Colette; Ncongwane, Katlego P; Sivakumar, Venkataraman; Coetzee, Gerrie; Metzger, Jean-Marc; Auriol, Frédérique; Deroo, Christine; Sauvage, Béatrice

2013-01-01

To estimate potential sunburn risk for schoolchildren and outdoor workers, ground-based ambient solar ultraviolet radiation (UVR) measurements were converted into possible child (5% of ambient solar UVR) and outdoor worker (20% of ambient solar UVR) solar UVR exposures by skin type and season for three coastal sites: Durban, Cape Point (South Africa) and Saint Denis (Reunion Island, France). Cumulative daily ambient solar UVR levels were relatively high at all sites, especially during summer, with maximum values of about 67, 57 and 74 Standard Erythemal Dose (SED) (1 SED = 100 J m(-2)) at Durban, Cape Point and Saint Denis respectively. Sunburn risk was evident for both children and outdoor workers, especially those with skin types I and II (extremely to moderately sensitive) during summer, early autumn and/or late spring at all three sites. Although results need to be verified with real-time, instantaneous and nonintegrated personal solar UVR measurements, this understanding of sunburn risk is useful for initiating the development skin cancer prevention and sun protection awareness campaigns in both countries. © 2013 The American Society of Photobiology.

SU-F-T-82: Dosimetric Evaluation of a Shield Used for Hemi-Body Skin Electron Irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rivers, C; Singh, A; AlDahlawi, I

Purpose: We had several mycosis fungoides patients with a limited disease to about half of the skin surface. A custom-made plywood shield was used to protect the non-targeted skin region with our total skin electron irradiation (TSEI) technique. We report a dosimetric evaluation for our “hemi-body” skin electron irradiation technique. Methods: The technique is similar to our clinical total skin electron irradiation (TSEI), performed with a six-pair dual field (Stanford technique) at an extended source-to-skin distance (SSD) of 377 cm, with the addition of a plywood shield placed 50 cm from the patient. The shield is made of three layersmore » of standard 5/8″ thick plywood (total thickness of 4.75 cm) that are clamped securely on an adjustable-height stand. Gafchromic EBT3 films were used in assessing the shield’s transmission factor and the extend of the dose penumbra region. To verify the dose delivered for hemi-body skin radiation in a real patient treatment, in-vivo dosimetry using Gafchromic EBT3 films were performed. Film pieces were taped on the patient skin to measure the dose received during the first two fractions, placed on the forehead and upper body (shielded region); and also at the level of pelvic area, left thigh, and left ankle. Results: The shield transmission factor was found to be 10%, and the width of the penumbra (80-to-20% dose fall-off) was about 12 cm. In-vivo dosimetry of a real case confirmed the expected shielded area dose. Conclusion: Hemi-Body skin electron irradiation at an extended SSD is feasible with the addition of a plywood shield at a distance from patient skin. The penumbra dose region and the shield’s transmission factor should be evaluated prior to clinical use. We have treated several hemi-body skin patients with our custom-made plywood shield, the current patient measurements are representative of these for other patients as well.« less

Determination of sulfadiazine, trimethoprim, and N(4) -acetyl-sulfadiazine in fish muscle plus skin by Liquid Chromatography-Mass Spectrometry. Withdrawal-time calculation after in-feed administration in gilthead sea bream (Sparus aurata L.) fed two different diets.

PubMed

Zonaras, V; Tyrpenou, A; Alexis, M; Koupparis, M

2016-10-01

This study presents a depletion study for sulfadiazine and trimethoprim in muscle plus skin of gilthead sea bream (Sparus aurata L.). N(4) -acetyl-sulfadiazine, the main metabolite of sulfadiazine (SDZ), was also examined. The fish were held in seawater at a temperature of 24-26 °C. SDZ and trimethoprim (TMP) were administered orally with medicated feed for five consecutive days at daily doses of 25 mg SDZ and 5 mg TMP per kg of fish body weight per day. Two different diets, fish oil- and plant oil-based diets, were investigated. Ten fish were sampled at each of the days 1, 3, 5, 6, 8, 9, 10, and 12 after the start of veterinary medicine administration. However for the calculation of the withdrawal periods, sampling day 1 was set as 24 h after the last dose of the treatment. Fish samples were analyzed for SDZ, TMP, and acetyl-sulfadiazine (AcSDZ) residues by liquid chromatography-mass spectrometry. SDZ and TMP concentrations declined rapidly from muscle plus skin. Considering a maximum residue limit of 100 μg/kg for the total of sulfonamides and 50 μg/kg for TMP residues in fish muscle plus skin, the withdrawal periods of the premix trimethoprim-sulfadiazine 50% were calculated as 5 and 6 days, at 24-26 °C, in fish oil (FO) and plant oil (PO) groups, respectively. The investigation of this work is important to protect consumers by controlling the undesirable residues in fish. © 2016 John Wiley & Sons Ltd.

Skin dose mapping for fluoroscopically guided interventions.

PubMed

Johnson, Perry B; Borrego, David; Balter, Stephen; Johnson, Kevin; Siragusa, Daniel; Bolch, Wesley E

2011-10-01

To introduce a new skin dose mapping software system for interventional fluoroscopy dose assessment and to analyze the benefits and limitations of patient-phantom matching. In this study, a new software system was developed for visualizing patient skin dose during interventional fluoroscopy procedures. The system works by translating the reference point air kerma to the location of the patient's skin, which is represented by a computational model. In order to orient the model with the x-ray source, geometric parameters found within the radiation dose structured report (RDSR) are used along with a limited number of in-clinic measurements. The output of the system is a visual indication of skin dose mapped onto an anthropomorphic model at a resolution of 5 mm. In order to determine if patient-dependent and patient-sculpted models increase accuracy, peak skin dose was calculated for each of 26 patient-specific models and compared with doses calculated using an elliptical stylized model, a reference hybrid model, a matched patient-dependent model and one patient-sculpted model. Results were analyzed in terms of a percent difference using the doses calculated using the patient-specific model as the true standard. Anthropometric matching, including the use of both patient-dependent and patient-sculpted phantoms, was shown most beneficial for left lateral and anterior-posterior projections. In these cases, the percent difference using a reference model was between 8 and 20%, using a patient-dependent model between 7 and 15%, and using a patient-sculpted model between 3 and 7%. Under the table tube configurations produced errors less than 5% in most situations due to the flattening affects of the table and pad, and the fact that table height is the main determination of source-to-skin distance for these configurations. In addition to these results, several skin dose maps were produced and a prototype display system was placed on the in-clinic monitor of an interventional fluoroscopy system. The skin dose mapping program developed in this work represents a new tool that, as the RDSR becomes available through automated export or real-time streaming, can provide the interventional physician information needed to modify behavior when clinically appropriate. The program is nonproprietary and transferable, and also functions independent to the software systems already installed on the control room workstation. The next step will be clinical implementation where the workflow will be optimized along with further analysis of real-time capabilities.

High dose rates obtained outside ISS in June 2015 during SEP event

NASA Astrophysics Data System (ADS)

Dachev, T. P.; Tomov, B. T.; Matviichuk, Yu. N.; Dimitrov, Pl. G.; Bankov, N. G.

2016-06-01

The R3DR2 instrument performed measurements in the European Space Agency (ESA) EXPOSE-R2 platform outside the Russian "Zvezda" module of the International Space Station (ISS) in the period 24 October 2014-11 January 2016. It is the Liulin-type deposited energy spectrometer (DES) (Dachev et al., 2015a). Took place in November 2014, this was the first attempt to monitor a small solar energetic particle (SEP) event outside ISS using the Liulin-type DES (Dachev et al., 2015d). In this study, we describe the dosimetric characteristics of the largest SEP event, observed on 22 June 2015 with the R3DR2 instrument outside ISS. The main finding of this study is that SEP protons with a minimum energy of approximately 7 MeV at the surface of the R3DR2 detector produced high dose rates, reaching >5000 μGy h-1, while the inner radiation belt maximum dose was at the level of 2200 μGy h-1. If a virtual external vehicle activity (EVA) was performed in the same period of the SEP maximum on 22 June 2015, the doses obtained in the skin of cosmonauts/astronauts can reach 2.84 mGy after 6.5 h, which is similar to the average absorbed dose inside ISS for 15 days (Reitz et al., 2005). A comparison with other extreme events measured with Liulin-type instruments shows that SEPs similar to that observed on 22 June 2015 could be one of the most dangerous events for the cosmonauts/astronauts involved in EVA.

Single high-dose irradiation aggravates eosinophil-mediated fibrosis through IL-33 secreted from impaired vessels in the skin compared to fractionated irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Eun-Jung, E-mail: forejs2@yuhs.ac; Kim, Jun Won, E-mail: JUNWON@yuhs.ac; Yoo, Hyun, E-mail: gochunghee@yuhs.ac

We have revealed in a porcine skin injury model that eosinophil recruitment was dose-dependently enhanced by a single high-dose irradiation. In this study, we investigated the underlying mechanism of eosinophil-associated skin fibrosis and the effect of high-dose-per-fraction radiation. The dorsal skin of a mini-pig was divided into two sections containing 4-cm{sup 2} fields that were irradiated with 30 Gy in a single fraction or 5 fractions and biopsied regularly over 14 weeks. Eosinophil-related Th2 cytokines such as interleukin (IL)-4, IL-5, and C–C motif chemokine-11 (CCL11/eotaxin) were evaluated by quantitative real-time PCR. RNA-sequencing using 30 Gy-irradiated mouse skin and functional assays in amore » co-culture system of THP-1 and irradiated-human umbilical vein endothelial cells (HUVECs) were performed to investigate the mechanism of eosinophil-mediated radiation fibrosis. Single high-dose-per-fraction irradiation caused pronounced eosinophil accumulation, increased profibrotic factors collagen and transforming growth factor-β, enhanced production of eosinophil-related cytokines including IL-4, IL-5, CCL11, IL-13, and IL-33, and reduced vessels compared with 5-fraction irradiation. IL-33 notably increased in pig and mouse skin vessels after single high-dose irradiation of 30 Gy, as well as in irradiated HUVECs following 12 Gy. Blocking IL-33 suppressed the migration ability of THP-1 cells and cytokine secretion in a co-culture system of THP-1 cells and irradiated HUVECs. Hence, high-dose-per-fraction irradiation appears to enhance eosinophil-mediated fibrotic responses, and IL-33 may be a key molecule operating in eosinophil-mediated fibrosis in high-dose-per fraction irradiated skin. - Highlights: • Single high-dose irradiation aggravates eosinophil-mediated fibrosis through IL-33. • Vascular endothelial cells damaged by high-dose radiation secrete IL-33. • Blocking IL-33 suppressed migration of inflammatory cells and cytokine secretion. • IL-33 is a key in eosinophil-mediated fibrosis in high-dose-per-fraction radiation.« less

Evaluation of β-blocker gel and effect of dosing volume for topical delivery.

PubMed

Zhang, Qian; Chantasart, Doungdaw; Li, S Kevin

2015-05-01

Although topical administration of β-blockers is desired because of the improved therapeutic efficacy and reduced systemic adverse effects compared with systemic administration in the treatment of infantile hemangioma, the permeation of β-blockers across skin under finite dose conditions has not been systematically studied and an effective topical β-blocker formulation for skin application is not available. The present study evaluated the permeation of β-blockers propranolol, betaxolol, and timolol across human epidermal membrane (HEM) from a topical gel in Franz diffusion cells in vitro under various dosing conditions. The effects of occlusion and dosing volume on percutaneous absorption of β-blockers from the gel were studied. The permeation data were compared with those of finite dose diffusion theory. The results showed that skin permeation of β-blockers generally could be enhanced two to three times by skin occlusion. The cumulative amounts of β-blockers permeated across HEM increased with increasing dosing volume. An adequate fit was obtained between the theoretical curve and experimental permeation data, indicating that the experimental results of the gel are consistent with finite dose diffusion theory. In conclusion, the findings suggest the feasibility of using topical gels of β-blockers for infantile hemangioma treatment and topical application with skin occlusion is preferred. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

The impact of skin colour on human photobiological responses.

PubMed

Fajuyigbe, Damilola; Young, Antony R

2016-11-01

Terrestrial solar ultraviolet radiation (UVR) exerts both beneficial and adverse effects on human skin. Epidemiological studies show a lower incidence of skin cancer in people with pigmented skins compared to fair skins. This is attributed to photoprotection by epidermal melanin, as is the poorer vitamin D status of those with darker skins. We summarize a wide range of photobiological responses across different skin colours including DNA damage and immunosuppression. Some studies show the generally modest photoprotective properties of melanin, but others show little or no effect. DNA photodamage initiates non-melanoma skin cancer and is reduced by a factor of about 3 in pigmented skin compared with white skin. This suggests that if such a modest reduction in DNA damage can result in the significantly lower skin cancer incidence in black skin, the use of sunscreen protection might be extremely beneficial for susceptible population. Many contradictory results may be explained by protocol differences, including differences in UVR spectra and exposure protocols. We recommend that skin type comparisons be done with solar-simulated radiation and standard erythema doses or physical doses (J/m 2 ) rather than those based solely on clinical endpoints such as minimal erythema dose (MED). © 2016 The Authors. Pigment Cell & Melanoma Research Published by John Wiley & Sons Ltd.

Influence of a Commercial Lead Apron on Patient Skin Dose Delivered During Oral and Maxillofacial Examinations under Cone Beam Computed Tomography (CBCT).

PubMed

Schulze, Ralf Kurt Willy; Sazgar, Mahssa; Karle, Heiko; de Las Heras Gala, Hugo

2017-08-01

The purpose of this paper is to investigate the impact of a commercial lead apron on patient skin dose delivered during maxillofacial CBCT in five critical regions by means of solid-state-dosimetry. Five anatomical regions (thyroid gland, left and right breast, gonads, back of the phantom torso) in an adult female anthropomorphic phantom were selected for dose measurement by means of the highly sensitive solid-state dosimeter QUART didoSVM. Ten repeated single exposures were assessed for each patient body region for a total of five commercial CBCT devices with and without a lead apron present. Shielded and non-shielded exposures were compared under the paired Wilcoxon test, with absolute and relative differences computed. Reproducibility was expressed as the coefficient of variation (CV) between the 10 repeated assessments. The highest doses observed at skin level were found at the thyroid (mean shielded ± SD: 450.5 ± 346.7 μGy; non-shielded: 339.2 ± 348.8 μGy, p = 0.4922). Shielding resulted in a highly significant (p < 0.001) 93% dose reduction in skin dose in the female breast region with a mean non-shielded dose of approximately 35 μGy. Dose reduction was also significantly lower for the back-region (mean: -65%, p < 0.0001) as well as for the gonad-region (mean: -98%, p < 0.0001) in the shielded situation. Reproducibility was inversely correlated to skin dose (Rspearman = -0.748, p < 0.0001) with a mean CV of 10.45% (SD: 24.53 %). Skin dose in the thyroid region of the simulated patient was relatively high and not influenced by the lead apron, which did not shield this region. Dose reduction by means of a commercial lead apron was significant in all other regions, particularly in the region of the female breast.

In vitro dose measurements in a human cadaver with abdomen/pelvis CT scans.

PubMed

Zhang, Da; Padole, Atul; Li, Xinhua; Singh, Sarabjeet; Khawaja, Ranish Deedar Ali; Lira, Diego; Liu, Tianyu; Shi, Jim Q; Otrakji, Alexi; Kalra, Mannudeep K; Xu, X George; Liu, Bob

2014-09-01

To present a study of radiation dose measurements with a human cadaver scanned on a clinical CT scanner. Multiple point dose measurements were obtained with high-accuracy Thimble ionization chambers placed inside the stomach, liver, paravertebral gutter, ascending colon, left kidney, and urinary bladder of a human cadaver (183 cm in height and 67.5 kg in weight) whose abdomen/pelvis region was scanned repeatedly with a multidetector row CT. The flat energy response and precision of the dosimeters were verified, and the slight differences in each dosimeter's response were evaluated and corrected to attain high accuracy. In addition, skin doses were measured for radiosensitive organs outside the scanned region with OSL dosimeters: the right eye, thyroid, both nipples, and the right testicle. Three scan protocols were used, which shared most scan parameters but had different kVp and mA settings: 120-kVp automA, 120-kVp 300 mA, and 100-kVp 300 mA. For each protocol three repeated scans were performed. The tube starting angle (TSA) was found to randomly vary around two major conditions, which caused large fluctuations in the repeated point dose measurements: for the 120-kVp 300 mA protocol this angle changed from approximately 110° to 290°, and caused 8%-25% difference in the point dose measured at the stomach, liver, colon, and urinary bladder. When the fluctuations of the TSA were small (within 5°), the maximum coefficient of variance was approximately 3.3%. The soft tissue absorbed doses averaged from four locations near the center of the scanned region were 27.2±3.3 and 16.5±2.7 mGy for the 120 and 100-kVp fixed-mA scans, respectively. These values were consistent with the corresponding size specific dose estimates within 4%. The comparison of the per-100-mAs tissue doses from the three protocols revealed that: (1) dose levels at nonsuperficial locations in the TCM scans could not be accurately deduced by simply scaling the fix-mA doses with local mA values; (2) the general power law relationship between dose and kVp varied from location to location, with the power index ranged between 2.7 and 3.5. The averaged dose measurements at both nipples, which were about 0.6 cm outside the prescribed scan region, ranged from 23 to 27 mGy at the left nipple, and varied from 3 to 20 mGy at the right nipple over the three scan protocols. Large fluctuations over repeated scans were also observed, as a combined result of helical scans of large pitch (1.375) and small active areas of the skin dosimeters. In addition, the averaged skin dose fell off drastically with the distance to the nearest boundary of the scanned region. This study revealed the complexity of CT dose fluctuation and variation with a human cadaver.

Measurement of skin dose from cone-beam computed tomography imaging.

PubMed

Akyalcin, Sercan; English, Jeryl D; Abramovitch, Kenneth M; Rong, Xiujiang J

2013-10-09

To measure surface skin dose from various cone-beam computed tomography (CBCT) scanners using point-dosimeters. A head anthropomorphic phantom was used with nanoDOT optically stimulated luminescence (OSL) dosimeters (Landauer Corp., Glenwood, IL) attached to various anatomic landmarks. The phantom was scanned using multiple exposure protocols for craniofacial evaluations in three different CBCT units and a conventional x-ray imaging system. The dosimeters were calibrated for each of the scan protocols on the different imaging systems. Peak skin dose and surface doses at the eye lens, thyroid, submandibular and parotid gland levels were measured. The measured skin doses ranged from 0.09 to 4.62 mGy depending on dosimeter positions and imaging systems. The average surface doses to the lens locations were ~4.0 mGy, well below the threshold for cataractogenesis (500 mGy). The results changed accordingly with x-ray tube output (mAs and kV) and also were sensitive to scan field of view (SFOV). As compared to the conventional panoramic and cephalometric imaging system, doses from all three CBCT systems were at least an order of magnitude higher. Peak skin dose and surface doses at the eye lens, thyroid, and salivary gland levels measured from the CBCT imaging systems were lower than the thresholds to induce deterministic effects. However, our findings do not justify the routine use of CBCT imaging in orthodontics considering the lifetime-attributable risk to the individual.

Measurement of skin dose from cone-beam computed tomography imaging

PubMed Central

2013-01-01

Objective To measure surface skin dose from various cone-beam computed tomography (CBCT) scanners using point-dosimeters. Materials & methods A head anthropomorphic phantom was used with nanoDOT optically stimulated luminescence (OSL) dosimeters (Landauer Corp., Glenwood, IL) attached to various anatomic landmarks. The phantom was scanned using multiple exposure protocols for craniofacial evaluations in three different CBCT units and a conventional x-ray imaging system. The dosimeters were calibrated for each of the scan protocols on the different imaging systems. Peak skin dose and surface doses at the eye lens, thyroid, submandibular and parotid gland levels were measured. Results The measured skin doses ranged from 0.09 to 4.62 mGy depending on dosimeter positions and imaging systems. The average surface doses to the lens locations were ~4.0 mGy, well below the threshold for cataractogenesis (500 mGy). The results changed accordingly with x-ray tube output (mAs and kV) and also were sensitive to scan field of view (SFOV). As compared to the conventional panoramic and cephalometric imaging system, doses from all three CBCT systems were at least an order of magnitude higher. Conclusions Peak skin dose and surface doses at the eye lens, thyroid, and salivary gland levels measured from the CBCT imaging systems were lower than the thresholds to induce deterministic effects. However, our findings do not justify the routine use of CBCT imaging in orthodontics considering the lifetime-attributable risk to the individual. PMID:24192155

Radiation sterilization of skin allograft

NASA Astrophysics Data System (ADS)

Kairiyama, E.; Horak, C.; Spinosa, M.; Pachado, J.; Schwint, O.

2009-07-01

In the treatment of burns or accidental loss of skin, cadaveric skin allografts provide an alternative to temporarily cover a wounded area. The skin bank facility is indispensable for burn care. The first human skin bank was established in Argentina in 1989; later, 3 more banks were established. A careful donor selection is carried out according to the national regulation in order to prevent transmissible diseases. As cadaveric human skin is naturally highly contaminated, a final sterilization is necessary to reach a sterility assurance level (SAL) of 10 -6. The sterilization dose for 106 batches of processed human skin was determined on the basis of the Code of Practice for the Radiation Sterilization of Tissue Allografts: Requirements for Validation and Routine Control (2004) and ISO 11137-2 (2006). They ranged from 17.6 to 33.4 kGy for bioburdens of >10-162.700 CFU/100 cm 2. The presence of Gram negative bacteria was checked for each produced batch. From the analysis of the experimental results, it was observed that the bioburden range was very wide and consequently the estimated sterilization doses too. If this is the case, the determination of a tissue-specific dose per production batch is necessary to achieve a specified requirement of SAL. Otherwise if the dose of 25 kGy is preselected, a standardized method for substantiation of this dose should be done to confirm the radiation sterilization process.

Deposition of radon progeny on skin surfaces and resulting radiation doses in radon therapy.

PubMed

Tempfer, H; Hofmann, W; Schober, A; Lettner, H; Dinu, A L

2010-05-01

In the Gastein valley, Austria, radon-rich thermal water and air have been used for decades for the treatment of various diseases. To explore the exposure pathway of radon progeny adsorbed to the skin, progeny activities on the skin of patients exposed to thermal water (in a bathtub) and hot vapour (in a vapour chamber) were measured by alpha spectrometry. Average total alpha activities on the patients' skin varied from 1.2 to 4.1 Bq/cm(2) in the bathtub, and from 1.1 to 2.6 Bq/cm(2) in the vapour bath. Water pH-value and ion concentration did affect radon progeny adsorption on the skin, whereas skin greasiness and blood circulation did not. Measurements of the penetration of deposited radon progeny into the skin revealed a roughly exponential activity distribution in the upper layers of the skin. Based on the radon progeny surface activity concentrations and their depth distributions, equivalent doses to different layers of the skin, in particular to the Langerhans cells located in the epidermis, ranged from 0.12 mSv in the thermal bath to 0.33 mSv in the vapour bath, exceeding equivalent doses to the inner organs (kidneys) by inhaled radon and progeny by about a factor 3, except for the lung, which receives the highest doses via inhalation. These results suggest that radon progeny attachment on skin surfaces may play a major role in the dosimetry for both thermal water and hot vapour treatment schemes.

Clinical implementation of total skin electron irradiation treatment with a 6 MeV electron beam in high-dose total skin electron mode

NASA Astrophysics Data System (ADS)

Lucero, J. F.; Rojas, J. I.

2016-07-01

Total skin electron irradiation (TSEI) is a special treatment technique offered by modern radiation oncology facilities, given for the treatment of mycosis fungoides, a rare skin disease, which is type of cutaneous T-cell lymphoma [1]. During treatment the patient's entire skin is irradiated with a uniform dose. The aim of this work is to present implementation of total skin electron irradiation treatment using IAEA TRS-398 code of practice for absolute dosimetry and taking advantage of the use of radiochromic films.

Clinical implementation of total skin electron irradiation treatment with a 6 MeV electron beam in high-dose total skin electron mode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lucero, J. F., E-mail: fernando.lucero@hoperadiotherapy.com.gt; Hope International, Guatemala; Rojas, J. I., E-mail: isaac.rojas@siglo21.cr

Total skin electron irradiation (TSEI) is a special treatment technique offered by modern radiation oncology facilities, given for the treatment of mycosis fungoides, a rare skin disease, which is type of cutaneous T-cell lymphoma [1]. During treatment the patient’s entire skin is irradiated with a uniform dose. The aim of this work is to present implementation of total skin electron irradiation treatment using IAEA TRS-398 code of practice for absolute dosimetry and taking advantage of the use of radiochromic films.

Skin Dosimetry in Breast Teletherapy on a Phantom Anthropomorphic and Anthropometric Phantom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batista Nogueira, Luciana; Lemos Silva, Hugo Leonardo; Donato da Silva, Sabrina

This paper addresses the breast teletherapy dosimetry. The goal is to evaluate and compare absorbed doses in equivalent skin tissue, TE-skin, of an anthropomorphic and anthropometric breast phantom submitted to breast radiotherapy. The methodology involved the reproduction of a set of tomographic images of the phantom; the elaboration of conformational radiotherapy planning in the SOMAVISION and CadPlan (TPS) software; and the synthetic breast irradiation by parallel opposed fields in 3D conformal teletherapy at 6 MV linear accelerator Clinac-2100 C from VARIAN with prescribed dose (PD) of 180 cGy to the target volume (PTV), referent to the glandular tissue. Radiochromic filmsmore » EBT2 were selected as dosimeters. Two independent calibration processes of films with solid water Gammex 457 plates and water filled box were produced. Curves of optical density (OD) versus absorbed dose were produced. Dosimeters were positioned in the external region of the breast phantom in contact with TE-skin, area of 4.0 cm{sup 2} each. The irradiation process was prepared in duplicate to check the reproducibility of the technique. The radiochromic films were scanned and their response in RGB (Red, Green, Blue) analyzed by the ImageJ software. The optical density was obtained and converted to dose based on the calibration curves. Thus, the spatial dose distribution in the skin was reproduced. The absorbed doses measured on the radiochromic films in TE-skin showed values between upper and lower quadrants at 9 o'clock in the range of 54% of PD, between the upper and lower quadrants 3 o'clock in the range of 72% and 6 o'clock at the lower quadrant in the range of 68 % of PD. The values are ±64% (p <0.05) according to the TPS. It is concluded that the depth dose measured in solid water plates or water box reproduce equivalent dose values for both calibration processes of the radiochromic films. It was observed that the skin received doses ranging from 50% to 78% of the prescribed dose after two parallel opposed irradiation fields. (authors)« less

CALCULATIONAL TOOL FOR SKIN CONTAMINATION DOSE ESTIMATE

DOE Office of Scientific and Technical Information (OSTI.GOV)

HILL, R.L.

2005-03-31

A spreadsheet calculational tool was developed to automate the calculations performed for estimating dose from skin contamination. This document reports on the design and testing of the spreadsheet calculational tool.

SU-E-T-373: Evaluation and Reduction of Contralateral Skin /subcutaneous Dose for Tangential Breast Irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Butson, M; Carroll, S; Whitaker, M

2015-06-15

Purpose: Tangential breast irradiation is a standard treatment technique for breast cancer therapy. One aspect of dose delivery includes dose delivered to the skin caused by electron contamination. This effect is especially important for highly oblique beams used on the medical tangent where the electron contamination deposits dose on the contralateral breast side. This work aims to investigate and predict as well as define a method to reduce this dose during tangential breast radiotherapy. Methods: Analysis and calculation of breast skin and subcutaneous dose is performed using a Varian Eclipse planning system, AAA algorithm for 6MV x-ray treatments. Measurements weremore » made using EBT3 Gafchromic film to verify the accuracy of planning data. Various materials were tested to assess their ability to remove electron contamination on the contralateral breast. Results: Results showed that the Varian Eclipse AAA algorithm could accurately estimate contralateral breast dose in the build-up region at depths of 2mm or deeper. Surface dose was underestimated by the AAA algorithm. Doses up to 12% of applied dose were seen on the contralateral breast surface and up to 9 % at 2mm depth. Due to the nature of this radiation, being mainly low energy electron contamination, a bolus material could be used to reduce this dose to less than 3%. This is accomplished by 10 mm of superflab bolus or by 1 mm of lead. Conclusion: Contralateral breast skin and subcutaneous dose is present for tangential breast treatment and has been measured to be up to 12% of applied dose from the medial tangent beam. This dose is deposited at shallow depths and is accurately calculated by the Eclipse AAA algorithm at depths of 2mm or greater. Bolus material placed over the contralateral can be used to effectively reduce this skin dose.« less

SU-D-207-03: Development of 4D-CBCT Imaging System with Dual Source KV X-Ray Tubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakamura, M; Ishihara, Y; Matsuo, Y

Purpose: The purposes of this work are to develop 4D-CBCT imaging system with orthogonal dual source kV X-ray tubes, and to determine the imaging doses from 4D-CBCT scans. Methods: Dual source kV X-ray tubes were used for the 4D-CBCT imaging. The maximum CBCT field of view was 200 mm in diameter and 150 mm in length, and the imaging parameters were 110 kV, 160 mA and 5 ms. The rotational angle was 105°, the rotational speed of the gantry was 1.5°/s, the gantry rotation time was 70 s, and the image acquisition interval was 0.3°. The observed amplitude of infraredmore » marker motion during respiration was used to sort each image into eight respiratory phase bins. The EGSnrc/BEAMnrc and EGSnrc/DOSXYZnrc packages were used to simulate kV X-ray dose distributions of 4D-CBCT imaging. The kV X-ray dose distributions were calculated for 9 lung cancer patients based on the planning CT images with dose calculation grid size of 2.5 x 2.5 x 2.5 mm. The dose covering a 2-cc volume of skin (D2cc), defined as the inner 5 mm of the skin surface with the exception of bone structure, was assessed. Results: A moving object was well identified on 4D-CBCT images in a phantom study. Given a gantry rotational angle of 105° and the configuration of kV X-ray imaging subsystems, both kV X-ray fields overlapped at a part of skin surface. The D2cc for the 4D-CBCT scans was in the range 73.8–105.4 mGy. Linear correlation coefficient between the 1000 minus averaged SSD during CBCT scanning and D2cc was −0.65 (with a slope of −0.17) for the 4D-CBCT scans. Conclusion: We have developed 4D-CBCT imaging system with dual source kV X-ray tubes. The total imaging dose with 4D-CBCT scans was up to 105.4 mGy.« less

Fluoroscopically Guided Interventional Procedures: A Review of Radiation Effects on Patients’ Skin and Hair

DTIC Science & Technology

2010-02-01

subsequent research has yielded additional in- sights. This review is a consensus report of current scien- tifi c data. Expected skin reactions for an...table has been cited and reproduced Essentials The minimum radiation dose n causing a specifi c type of reac- tion in the skin or hair is best...expressed in terms of a range of doses, rather than a single threshold dose. The times of onset and resolution n of specifi c radiation injuries

TU-D-209-02: A Backscatter Point Spread Function for Entrance Skin Dose Determination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vijayan, S; Xiong, Z; Shankar, A

Purpose: To determine the distribution of backscattered radiation to the skin resulting from a non-uniform distribution of primary radiation through convolution with a backscatter point spread function (PSF). Methods: A backscatter PSF is determined using Monte Carlo simulation of a 1 mm primary beam incident on a 30 × 30 cm × 20 cm thick PMMA phantom using EGSnrc software. A primary profile is similarly obtained without the phantom and the difference from the total provides the backscatter profile. This scatter PSF characterizes the backscatter spread for a “point” primary interaction and can be convolved with the entrance primary dosemore » distribution to obtain the total entrance skin dose. The backscatter PSF was integrated into the skin dose tracking system (DTS), a graphical utility for displaying the color-coded skin dose distribution on a 3D graphic of the patient during interventional fluoroscopic procedures. The backscatter convolution method was validated for the non-uniform beam resulting from the use of an ROI attenuator. The ROI attenuator is a copper sheet with about 20% primary transmission (0.7 mm thick) containing a circular aperture; this attenuator is placed in the beam to reduce dose in the periphery while maintaining full dose in the region of interest. The DTS calculated primary plus backscatter distribution is compared to that measured with GafChromic film and that calculated using EGSnrc Monte-Carlo software. Results: The PSF convolution method used in the DTS software was able to account for the spread of backscatter from the ROI region to the region under the attenuator. The skin dose distribution determined using DTS with the ROI attenuator was in good agreement with the distributions measured with Gafchromic film and determined by Monte Carlo simulation Conclusion: The PSF convolution technique provides an accurate alternative for entrance skin dose determination with non-uniform primary x-ray beams. Partial support from NIH Grant R01-EB002873 and Toshiba Medical Systems Corp.« less

SU-E-T-09: A Clinical Implementation and Optimized Dosimetry Study of Freiberg Flap Skin Surface Treatment in High Dose Rate Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Syh, J; Syh, J; Patel, B

Purpose: This case study was designated to confirm the optimized plan was used to treat skin surface of left leg in three stages. 1. To evaluate dose distribution and plan quality by alternating of the source loading catheters pattern in flexible Freiberg Flap skin surface (FFSS) applicator. 2. To investigate any impact on Dose Volume Histogram (DVH) of large superficial surface target volume coverage. 3. To compare the dose distribution if it was treated with electron beam. Methods: The Freiburg Flap is a flexible mesh style surface mold for skin radiation or intraoperative surface treatments. The Freiburg Flap consists ofmore » multiple spheres that are attached to each other, holding and guiding up to 18 treatment catheters. The Freiburg Flap also ensures a constant distance of 5mm from the treatment catheter to the surface. Three treatment trials with individual planning optimization were employed: 18 channels, 9 channels of FF and 6 MeV electron beam. The comparisons were highlighted in target coverage, dose conformity and dose sparing of surrounding tissues. Results: The first 18 channels brachytherapy plan was generated with 18 catheters inside the skin-wrapped up flap (Figure 1A). A second 9 catheters plan was generated associated with the same calculation points which were assigned to match prescription for target coverage as 18 catheters plan (Figure 1B). The optimized inverse plan was employed to reduce the dose to adjacent structures such as tibia or fibula. The comparison of DVH’s was depicted on Figure 2. External beam of electron RT plan was depicted in Figure 3. Overcall comparisons among these three were illustrated in Conclusion: The 9-channel Freiburg flap flexible skin applicator offers a reasonably acceptable plan without compromising the coverage. Electron beam was discouraged to use to treat curved skin surface because of low target coverage and high dose in adjacent tissues.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Safigholi, Habib; Meigooni, A S.; University of Nevada Las Vegas

Purpose: Recently, different applicators are designed for treatment of the skin cancer such as scalp and legs, using Ir-192 HDR Brachytherapy Sources (IR-HDRS), Miniature Electronic Brachytherapy Sources (MEBXS), and External Electron Beam Radiation Therapy (EEBRT). Although, all of these methodologies may deliver the desired radiation dose to the skin, the dose to the underlying bone may become the limiting factor for selection of the optimum treatment technique. In this project the radiation dose delivered to the underlying bone has been evaluated as a function of the radiation source and thickness of the underlying bone. Methods: MC simulations were performed usingmore » MCNP5 code. In these simulations, the mono-energetic and non-divergent photon beams of 30 keV, 50 keV, and 70 keV for MEBXS, 380 keV photons for IR-HDRS, and 6 MeV mono-energetic electron beam for EEBRT were modeled. A 0.5 cm thick soft tissue (0.3 cm skin and 0.2 cm adipose) with underlying 0.5 cm cortical bone followed by 14 cm soft tissue are utilized for simulations. Results: Dose values to bone tissue as a function of beam energy and beam type, for a delivery of 5000 cGy dose to skin, were compared. These results indicate that for delivery of 5000 cGy dose to the skin surface with 30 keV, 50 keV, 70 keV of MEBXS, IR-HDRS, and EEBRT techniques, bone will receive 31750 cGy, 27450 cGy, 18550 cGy, 4875 cGy, and 10450 cGy, respectively. Conclusion: The results of these investigations indicate that, for delivery of the same skin dose, average doses received by the underlying bone are 5.2 and 2.2 times larger with a 50 keV MEBXS and EEBRT techniques than IR-HDRS, respectively.« less

Long-term outcome of accelerated partial breast irradiation using a multilumen balloon applicator in a patient with existing breast implants.

PubMed

Akhtari, Mani; Nitsch, Paige L; Bass, Barbara L; Teh, Bin S

2015-01-01

Accelerated partial breast irradiation is now an accepted component of breast-conserving therapy. However, data regarding long-term outcomes of patients treated with multilumen catheter systems who have existing breast implants are limited. We report the treatment and outcome of our patient who had existing bilateral silicone subpectoral implants at the time of presentation. Ultrasound-guided core needle biopsy of the right breast showed infiltrating mucinous carcinoma. Right breast lumpectomy revealed an 8 mm area of infiltrating ductal carcinoma with mucinous features and nuclear grade 1. A 4-5 cm Contura (Bard Biopsy Systems, Tempe, AZ) device was placed, and she was treated over the course of 5 days twice daily to a dose of 34 Gy using a high-dose-rate iridium-192 source. The planning target volume for evaluation was 73.9 cc. The percentage of the planning target volume for evaluation receiving 90%, 95%, and 100% of the prescribed dose was 99.9%, 99.3%, and 97.8%, respectively. The total implant volume was 234.5 cc and received a mean dose of 15.4 Gy and a maximum dose of 72.8 Gy. The percentage of implant volume receiving 50%, 75%, 100%, and 200% of the prescribed dose was 31.1%, 16.5%, 8.6%, 2.0%, and 0%, respectively. Maximum skin dose was 97% of the prescribed dose. With a followup of nearly 5 years, she continues to be cancer free with minimal late toxicities and good to excellent cosmetic outcome. Accelerated partial breast irradiation using a multilumen balloon applicator in patients with existing breast implants can safely be performed with excellent long-term cosmetic outcome. Further studies are needed to establish the absolute dosimetric tolerance of breast implants. Copyright © 2015 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Comparison of penetration and metabolism of [3H]diacetoxyscirpenol, [3H]verrucarin A and [3H]T-2 toxin in skin.

PubMed

Kemppainen, B W; Riley, R T; Biles-Thurlow, S

1987-05-01

The purpose of this research was to determine the rate of cutaneous penetration and metabolism of [3H]diacetoxyscirpenol (DAS) and [3H]verrucarin A (VCA) and compare these values to previously determined values for [3H]T-2 toxin (T-2), to compare the cutaneous penetration and metabolism of DAS in human and guinea-pig skin, and to compare the effects of dose and of two vehicles, methanol and dimethylsulphoxide (DMSO), on penetration rates. DAS or VCA was applied to the epidermal surface of excised skin, and the receptor fluid bathing the dermal surface was sampled periodically for 48 hr. Whether the applied dose (581 ng/cm2) was dissolved in methanol or DMSO, the rate of penetration through human skin was lower for VCA than for DAS or T-2, the rates for the two latter compounds being similar at this dose. Metabolism of DAS occurred during penetration through excised human skin and did not occur in the receptor fluid as a result of enzymes leaching out of the skin. VCA appeared to be metabolized by human skin, but this conclusion is tentative because of the relative instability of this compound. DAS penetrated significantly (P less than 0.05) faster through excised guinea-pig skin than through human skin. Metabolism of DAS was greater in human skin than in guinea-pig skin. When compared with methanol, DMSO increased the penetration of DAS and VCA by factors of between 7 and 52. At the low dose (79 ng/cm2) DAS penetrated human and guinea-pig skin significantly (P less than 0.05) faster than T-2 using either vehicle.

DOSE-RESPONSE FOR UV-INDUCED IMMUNE SUPPRESSION IN PEOPLE OF COLOR: DIFFERENCES BASED ON ERYTHEMAL REACTIVITY RATHER THAN SKIN PIGMENTATION

EPA Science Inventory

Ultraviolet radiation (UVR) is known to suppress immune responses in human subjects. The purpose of this study was to develop dose responses across a broad range of skin pigmentation in order to facilitate risk assessment. UVR was administered using FS 20 bulbs. Skin pigmentation...

10 CFR 835.202 - Occupational dose limits for general employees.

Code of Federal Regulations, 2010 CFR

2010-01-01

... tissue other than the skin or the lens of the eye of 50 rems (0.5 Sv); (3) An equivalent dose to the lens of the eye of 15 rems (0.15 Sv); and (4) The sum of the equivalent dose to the skin or to any... 10 Energy 4 2010-01-01 2010-01-01 false Occupational dose limits for general employees. 835.202...

10 CFR 835.202 - Occupational dose limits for general employees.

Code of Federal Regulations, 2014 CFR

2014-01-01

... tissue other than the skin or the lens of the eye of 50 rems (0.5 Sv); (3) An equivalent dose to the lens of the eye of 15 rems (0.15 Sv); and (4) The sum of the equivalent dose to the skin or to any... 10 Energy 4 2014-01-01 2014-01-01 false Occupational dose limits for general employees. 835.202...

10 CFR 835.202 - Occupational dose limits for general employees.

Code of Federal Regulations, 2012 CFR

2012-01-01

... tissue other than the skin or the lens of the eye of 50 rems (0.5 Sv); (3) An equivalent dose to the lens of the eye of 15 rems (0.15 Sv); and (4) The sum of the equivalent dose to the skin or to any... 10 Energy 4 2012-01-01 2012-01-01 false Occupational dose limits for general employees. 835.202...

10 CFR 835.202 - Occupational dose limits for general employees.

Code of Federal Regulations, 2013 CFR

2013-01-01

... tissue other than the skin or the lens of the eye of 50 rems (0.5 Sv); (3) An equivalent dose to the lens of the eye of 15 rems (0.15 Sv); and (4) The sum of the equivalent dose to the skin or to any... 10 Energy 4 2013-01-01 2013-01-01 false Occupational dose limits for general employees. 835.202...

10 CFR 835.202 - Occupational dose limits for general employees.

Code of Federal Regulations, 2011 CFR

2011-01-01

... tissue other than the skin or the lens of the eye of 50 rems (0.5 Sv); (3) An equivalent dose to the lens of the eye of 15 rems (0.15 Sv); and (4) The sum of the equivalent dose to the skin or to any... 10 Energy 4 2011-01-01 2011-01-01 false Occupational dose limits for general employees. 835.202...

Phantom torso experiment on the international space station; flight measurements and calculations

NASA Astrophysics Data System (ADS)

Atwell, W.; Semones, E.; Cucinotta, F.

The Phantom Torso Experiment (PTE) first flew on the 10-day Space Shuttle mission STS-91 in June 1998 during a period near solar minimum. The PTE was re- f l o w n on the I ternational Space Station (ISS) Increment 2 mission from April-n A u g u s t 2001 during a period near solar maximum. The experiment was located with a suite of other radiation experiments in the US Lab module Human Research Facility (HRF) rack. The objective of the experiment was to measure space radiation exposures at several radiosensitive critical body organs (brain, thyroid, heart/lung, stomach and colon) and two locations on the surface (skin) of a modified RandoTM phantom. Prior to flight, active solid -state silicon dosimeters were located at the RandoTM critical body organ locations and passive dosimeters were placed at the two surface locations. Using a mathematically modified Computerized Anatomical Male (CAM) model, shielding distributions were generated for the five critical body organ and two skin locations. These shielding distributions were then combined with the ISS HRF rack shielding distribution to account for the total shielding "seen" by the PTE. Using the trapped proton and galactic cosmic radiation environment models and high -energy particle transport codes, absorbed dose, dose equivalent, and LET (linear energy transfer) values were computed for the seven dose point locations of interest. The results of these computations are compared with the actual flight measurements.

Monte Carlo simulations in CT for the study of the surface air kerma and energy imparted to phantoms of varying size and position

NASA Astrophysics Data System (ADS)

Avilés Lucas, P.; Dance, D. R.; Castellano, I. A.; Vañó, E.

2004-04-01

A Monte Carlo computational model of CT has been developed and used to investigate the effect of various physical factors on the surface air kerma length product, the peak surface air kerma, the air kerma length product within a phantom and the energy imparted. The factors investigated were the bow-tie filter and the size, shape and position of a phantom which simulates the patient. The calculations show that the surface air kerma length product and the maximum surface air kerma are mainly dependent on phantom position and decrease along the vertical axis of the CT plane as the phantom surface moves away from the isocentre along this axis. As a result, measurements using standard body dosimetry phantoms may underestimate the skin dose for real patients. This result is specially important for CT fluoroscopic procedures: for an adult patient the peak skin dose can be 37% higher than that estimated with a standard measurement on the body AAPM (American Association of Physicists in Medicine) phantom. The results also show that the energy imparted to a phantom is mainly influenced by phantom size and is nearly independent of phantom position (within 3%) and shape (up to 5% variation). However, variations of up to 30% were found for the air kerma to regions within the AAPM body phantom when it is moved vertically. This highlights the importance of calculating doses to organs taking into account their size and position within the gantry.

Development of action levels for MED/MPD skin-testing units in ultraviolet phototherapy

NASA Astrophysics Data System (ADS)

O'Connor, Una M.; O'Hare, Neil J.

2003-03-01

Ultraviolet (UV) Phototherapy is commonly used for treatment of skin diseases such as psoriasis and eczema. Treatment is carried out using UV phototherapy units, exposing all or part of the body for a certain exposure time. Prior to exposure in treatment units, an unaffected area of skin may be tested using UV skin-testing units in order to determine a suitable treatment regime. The exposure time at which barely perceptible erythema has developed is known as the Minimal Erythemal Dose (MED) for UVB therapy and Minimal Phototoxic Dose (MPD) for UVA therapy. This is used to determine the starting dose in the treatment regime. The presence of 'hotspots' and 'coldspots' in UV skin-testing units can result in inaccurate determination of MED/MPD. This could give rise to severe burns during treatment, or in a sub-optimal dose regime being used. Quality assurance protocols for UV phototherapy equipment have recently been developed and these protocols have highlighted the need for action levels for skin-testing units. An action level is a reference value, which is used to determine whether the difference in irradiance output level across a UV unit is acceptable. Current methodologies for skin-testing in Ireland have been characterised and errors introduced during testing have been estimated. Action levels have been developed based on analysis of errors and requirements of skin-testing.

Total skin electron irradiation for mycosis fungoides: relationship between acute toxicities and measured dose at different anatomic sites.

PubMed

Desai, K R; Pezner, R D; Lipsett, J A; Vora, N L; Luk, K H; Wong, J Y; Chan, S L; Findley, D O; Hill, L R; Marin, L A

1988-09-01

From June 1978 to June 1986, 50 patients with primary and recurrent mycosis fungoides were treated with total skin electron irradiation (TSEI), using the Stanford technique, to a total dose of 3600 cGy. TSEI was used alone, or in combination with low dose total body photon irradiation, or MOPP. Thermoluminescent dosimeter (TLD) measurements of the prescribed skin dose were obtained on twenty patients. The dorsum of the foot was 24% higher. The axillae, the bottom, and the arch of the foot were significantly underdosed. Frequencies of acute toxicities noted at 2000 cGy were: Skin, Grade I-II (RTOG) 80%. Partial epilation: scalp, 100%; eyebrows and at eyelashes, 20%. Nail dystrophy, 48%. Edema: hands and feet, 44%. Bullae: dorsum of feet, 8%; hands, 4%; and 3600 cGy: Skin, grade III 22%. Total epilation: scalp, 66%; eyebrows and eyelashes, 56%. Nail loss, 38%. Edema: hands and feet, 76%. Bullae: dorsum of feet, 34%; hands, 12%. Conjunctivitis, 4%. Large bullae, were more significant on the dorsum of the feet. Severe moist desquamation occurred in eight patients who had ulcerated lesions on initial presentation. Three patients were hospitalized due to ulceration and skin infection. All patients completed treatment after a short to moderate break. No patient developed skin necrosis, or corneal ulceration. No correlation exists between dose level, degree and onset of toxicity with previous chemotherapy or TBI. We conclude that the overall toxicity of TSEI is well tolerated.

Surface applicator calibration and commissioning of an electronic brachytherapy system for nonmelanoma skin cancer treatment.

PubMed

Rong, Yi; Welsh, James S

2010-10-01

The Xoft Axxent x-ray source has been used for treating nonmelanoma skin cancer since the surface applicators became clinically available in 2009. The authors report comprehensive calibration procedures for the electronic brachytherapy (eBx) system with the surface applicators. The Xoft miniature tube (model S700) generates 50 kVp low-energy x rays. The new surface applicators are available in four sizes of 10, 20, 35, and 50 mm in diameter. The authors' tests include measurements of dose rate, air-gap factor, output stability, depth dose verification, beam flatness and symmetry, and treatment planning with patient specific cutout factors. The TG-61 in-air method was used as a guideline for acquiring nominal dose-rate output at the skin surface. A soft x-ray parallel-plate chamber (PTW T34013) and electrometer was used for the output commissioning. GafChromic EBT films were used for testing the properties of the treatment fields with the skin applicators. Solid water slabs were used to verify the depth dose and cutout factors. Patients with basal cell or squamous cell carcinoma were treated with eBx using a calibrated Xoft system with the low-energy x-ray source and the skin applicators. The average nominal dose-rate output at the skin surface for the 35 mm applicator is 1.35 Gy/min with +/- 5% variation for 16 sources. The dose-rate output and stability (within +/- 5% variation) were also measured for the remaining three applicators. For the same source, the output variation is within 2%. The effective source-surface distance was calculated based on the air-gap measurements for four applicator sizes. The field flatness and symmetry are well within 5%. Percentage depth dose in water was provided by factory measurements and can be verified using solid water slabs. Treatment duration was calculated based on the nominal dose rate, the prescription fraction size, the depth dose percentage, and the cutout factor. The output factor needs to be measured for each case with varying shapes of cutouts. Together with TG-61, the authors' methodology provides comprehensive calibration procedures for medical physicists for using the Xoft eBx system and skin applicators for nonmelanoma skin cancer treatments.

Antiradiation UV Vaccine: UV Radiation, Biological effects, lesions and medical management - immune-therapy and immune-protection.

NASA Astrophysics Data System (ADS)

Popov, Dmitri; Jones, Jeffrey; Maliev, Slava

Key Words: Ultraviolet radiation,Standard Erythema Dose(SED), Minimal Erythema Dose(MED), Sun Burns, Solar Dermatitis, Sun Burned Disease, DNA Damage,Cell Damage, Antiradiation UV Vaccine, Immune-Prophylaxis of Sun Burned Diseases, Immune-Prophylaxis of Sun Burns, Immune-Therapy of Sun-Burned Disease and Sun Burns,Basal Cell Carcinoma (BCC), Squamous Cell Carcinoma (SCC), Toxic Epidermal Necrolysis(TEN). Introduction: High doses of UV generated by solar source and artificial sources create an exposure of mammals and other species which can lead to ultraviolet(UV)radiation- associated disease (including erythema, epilation, keratitis, etc.). UV radiation belongs to the non-ionizing part of the electromagnetic spectrum and ranges between 100 nm and 400 nm with 100 nm having been chosen arbitrarily as the boundary between non-ionizing and ionizing radiation, however EMR is a spectrum and UV can produce molecular ionization. UV radiation is conventionally categorized into 3 areas: UV-A (>315-400 nm),UV-B (>280-315 nm)and UV-C (>100-280 nm) [IARC,Working Group Reports,2005] An important consequence of stratospheric ozone depletion is the increased transmission of solar ultraviolet (UV)radiation to the Earth's lower atmosphere and surface. Stratospheric ozone levels have been falling, in certain areas, for the past several decades, so current surface ultraviolet-B (UV-B) radiation levels are thought to be close to their modern day maximum. [S.Madronich et al.1998] Overexposure of ultraviolet radiation a major cause of skin cancer including basal cell carcinoma (BCC), squamous cell carcinoma (SCC) { collectively referred to as “non-melanoma" skin cancer (NMSC) and melanoma as well, with skin cancers being the most common cancer in North America. [Armstrong et al. 1993, Gallagher et al. 2005] Methods and Experimental Design: Our experiments and testing of a novel UV “Antiradiation Vaccine” have employed a wide variety of laboratory animals which include : Chinchilla rabbits, 11-12 months old, live weight 3.5-3.7 (n=11), Balb mice, 2-3 months old, live weight 20-22 g (n=33), Wistar rats, 3-4 months old, live weight 180-220 g(n=33). The studies were approved by the Animal Care and Use Committee for ethical animal research equivalent, at each institution. Seven rabbits, ten mice, eleven Wistar rats were vaccinated with a UV antiradiation vaccine. A second group of animals was used as biological control which received vaccine but no UV Radiation and a third group of animals was used as control without any interventions. Before and after UV Radiation, Vaccination with the UV antiradiation vaccine were provided 17 days prior to UV exposure. The animals were irradiated by a DRT-1 UV generator lamp. The dose of irradiation for laboratory, experimental animals was 10-12 * Standard Erythema Dose (SED) at L=283,7 Laboratory animals were placed in to the box with ventilation. Results: Ultraviolet irradiation of the skin was performed with high doses and causes an inflammation or erythema in all experimental animals. However the grade of skin damage and inflammation was significantly different between animals protected by vaccination and non-protected, non-vaccinated animals. Animals UV-irradiated, but who did not receive the antiradiation vaccine suffered from extensive UV skin burns of second or third degree (grade 2-3). However, animals protected with the UV antiradiation vaccine demonstrated much mild forms of skin cellular injury - mainly erythema, first degree skin burns and a few small patches with second degree skin burns (grade 1-2). Discussion: The severity of skin damage depended on area of exposed skin, time and dose of UV irradiation. Skin injury could be divided into 4 major grades: 1. Faint erythema with dry desquamation. 2. Moderate to severe erythema. 3. Severe erythema with blistering, moist desquamation. 4. Toxic epidermal necrolysis. Mild doses of UV radiation and ionizing radiation can induce cell death by apoptosis and moderate and high doses of UV and ionizing radiation induce cell death by necrosis and generate systemic inflammatory response syndrome (SIRS), toxic multiple organ injury (TMOI), toxic multiple organ dysfunction syndromes (TMODS),and finally, toxic multiple organ failure (TMOF). [D.Popov et al.2012, Fliedner T.et al. 2005, T. Azizova et al. 2004] UV-B is a complete carcinogen that is absorbed by DNA and directly damages DNA. DNA damage induced by UV-B irradiation typically includes the formation of cyclobutane pyrimidine dimmers (CPD) and 6-4 photoproducts (6-4P)[IARC, Working Group Reports, M.Saraiya et al. 2004]. The pre-vaccinated animals seem to have a blunted injury response relative to the unvaccinated animals, presumably by reduction in the inflammatory response and secondary injury effects. The mechanism of action of the antiradiation vaccine, needs further evaluation. Conclusion: A UV antiradiation vaccine appears to demonstrate efficacy as a prophylactic agent for acute solar burns and toxicity. An antiradiation UV vaccine could be used in conjunction with adjunctive measures, e.g. antioxidants and UV barriers to reduce UV radiation toxicity. The authors of this experiments would like to propose further development work of the antiradiation UV vaccine to enhance the armamentarium for prophylaxis and prevention of the various forms skin cancer.

DOE Office of Scientific and Technical Information (OSTI.GOV)

McEachen, James C., E-mail: james.mceachen2@gmail.com; Leng, Shuai; Atwell, Thomas D.

IntroductionOnce reserved solely for non-surgical cases, percutaneous ablation is becoming an increasingly popular treatment option for a wider array of patients with small renal masses and the radiation risk needs to be better defined as this transition continues.Materials and MethodsRetrospective review of our renal tumor ablation database revealed 425 patients who underwent percutaneous ablation for treatment of 455 renal tumors over a 5-year time period. Imparted radiation dose information was reviewed for each procedure and converted to effective patient dose and skin dose using established techniques. Statistical analysis was performed with each ablative technique.ResultsFor the 331 cryoablation procedures, the meanmore » DLP was 6987 mGycm (SD = 2861) resulting in a mean effective dose of 104.7 mSv (SD = 43.5) and the mean CTDI{sub vol} was 558 mGy (SD = 439) resulting in a mean skin dose of 563.2 mGy (SD = 344.1). For the 124 RFA procedures, the mean DLP was 3485 mGycm (SD = 1630) resulting in a mean effective dose of 50.3 mSv (SD = 24.0) and the mean CTDI{sub vol} was 232 mGy (SD = 149) resulting in a mean skin dose of 233.2 mGy (SD = 117.4). The difference in patient radiation exposure between the two renal ablation techniques was statistically significant (p < 0.001).ConclusionBoth cryoablation and RFA imparted an average skin dose that was well below the 2 Gy deterministic threshold for appreciable sequela. Renal tumor cryoablation resulted in a mean skin and effective radiation dose more than twice that for RFA. The radiation exposure for both renal tumor ablation techniques was at the high end of the medical imaging radiation dose spectrum.« less

SU-F-T-654: Pacemaker Dose Estimate Using Optically Stimulated Luminescent Dosimeter for Left Breast Intraoperative Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Y; Goenka, A; Sharma, A

Purpose: To assess and report the in vivo dose for a patient with a pacemaker being treated in left breast intraoperative radiation therapy (IORT). The ZEISS Intrabeam 50 kVp X-ray beam with a spherical applicator was used. Methods: The optically stimulated luminescent dosimeters (OSLDs) (Landauer nanoDots) were employed and calibrated under the conditions of the Intrabeam 50 kVp X-rays. The nanoDots were placed on the patient at approximately 15 cm away from the lumpectomy cavity both under and above a shield of lead equivalence 0.25 mm (RayShield X-Drape D-110) covering the pacemaker area during IORT with a 5 cm sphericalmore » applicator. Results: The skin surface dose near the pacemaker during the IORT with a prescription of 20 Gy was measured as 4.0±0.8 cGy. The dose behind the shield was 0.06±0.01 Gy, demonstrating more than 98% dose reduction. The in vivo skin surface doses during a typical breast IORT at a 4.5 cm spherical applicator surface were further measured at 5, 10, 15, and 20 cm away to be 159±11 cGy, 15±1 cGy, 6.6±0.5 cGy, and 1.8±0.1 cGy, respectively. A power law fit to the dose versus the distance z from the applicator surface yields the dose fall off at the skin surface following z^-2.5, which can be used to estimate skin doses in future cases. The comparison to an extrapolation of depth dose in water reveals an underestimate of far field dose using the manufactory provided data. Conclusion: The study suggests the appropriateness of OSLD as an in vivo skin dosimeter in IORT using the Intrabeam system in a wide dose range. The pacemaker dose measured during the left breast IORT was within a safe limit.« less

Clinical application of a OneDose MOSFET for skin dose measurements during internal mammary chain irradiation with high dose rate brachytherapy in carcinoma of the breast.

PubMed

Kinhikar, Rajesh A; Sharma, Pramod K; Tambe, Chandrashekhar M; Mahantshetty, Umesh M; Sarin, Rajiv; Deshpande, Deepak D; Shrivastava, Shyam K

2006-07-21

In our earlier study, we experimentally evaluated the characteristics of a newly designed metal oxide semiconductor field effect transistor (MOSFET) OneDose in-vivo dosimetry system for Ir-192 (380 keV) energy and the results were compared with thermoluminescent dosimeters (TLDs). We have now extended the same study to the clinical application of this MOSFET as an in-vivo dosimetry system. The MOSFET was used during high dose rate brachytherapy (HDRBT) of internal mammary chain (IMC) irradiation for a carcinoma of the breast. The aim of this study was to measure the skin dose during IMC irradiation with a MOSFET and a TLD and compare it with the calculated dose with a treatment planning system (TPS). The skin dose was measured for ten patients. All the patients' treatment was planned on a PLATO treatment planning system. TLD measurements were performed to compare the accuracy of the measured results from the MOSFET. The mean doses measured with the MOSFET and the TLD were identical (0.5392 Gy, 15.85% of the prescribed dose). The mean dose was overestimated by the TPS and was 0.5923 Gy (17.42% of the prescribed dose). The TPS overestimated the skin dose by 9% as verified by the MOSFET and TLD. The MOSFET provides adequate in-vivo dosimetry for HDRBT. Immediate readout after irradiation, small size, permanent storage of dose and ease of use make the MOSFET a viable alternative for TLDs.

Inflammatory biomarkers of sulfur mustard analog 2-chloroethyl ethyl sulfide-induced skin injury in SKH-1 hairless mice.

PubMed

Tewari-Singh, Neera; Rana, Sumeet; Gu, Mallikarjuna; Pal, Arttatrana; Orlicky, David J; White, Carl W; Agarwal, Rajesh

2009-03-01

Sulfur mustard (HD) is an alkylating and cytotoxic chemical warfare agent, which inflicts severe skin toxicity and an inflammatory response. Effective medical countermeasures against HD-caused skin toxicity are lacking due to limited knowledge of related mechanisms, which is mainly attributed to the requirement of more applicable and efficient animal skin toxicity models. Using a less toxic analog of HD, chloroethyl ethyl sulfide (CEES), we identified quantifiable inflammatory biomarkers of CEES-induced skin injury in dose- (0.05-2 mg) and time- (3-168 h) response experiments, and developed a CEES-induced skin toxicity SKH-1 hairless mouse model. Topical CEES treatment at high doses caused a significant dose-dependent increase in skin bi-fold thickness indicating edema. Histopathological evaluation of CEES-treated skin sections revealed increases in epidermal and dermal thickness, number of pyknotic basal keratinocytes, dermal capillaries, neutrophils, macrophages, mast cells, and desquamation of epidermis. CEES-induced dose-dependent increases in epidermal cell apoptosis and basal cell proliferation were demonstrated by the terminal deoxynucleotidyl transferase (tdt)-mediated dUTP-biotin nick end labeling and proliferative cell nuclear antigen stainings, respectively. Following an increase in the mast cells, myeloperoxidase activity in the inflamed skin peaked at 24 h after CEES exposure coinciding with neutrophil infiltration. F4/80 staining of skin integuments revealed an increase in the number of macrophages after 24 h of CEES exposure. In conclusion, these results establish CEES-induced quantifiable inflammatory biomarkers in a more applicable and efficient SKH-1 hairless mouse model, which could be valuable for agent efficacy studies to develop potential prophylactic and therapeutic interventions for HD-induced skin toxicity.

Intravenous Single-Dose Toxicity of Redaporfin-Based Photodynamic Therapy in Rodents

PubMed Central

Rocha, Luis B.; Schaberle, Fábio; Dąbrowski, Janusz M.; Simões, Sérgio; Arnaut, Luis G.

2015-01-01

We assessed the tolerability and safety in rodents of a single intravenous (i.v.) dose of redaporfin, a novel photosensitizer for Photodynamic Therapy (PDT) of cancer. Two approaches were used to evaluate acute toxicity: (i) a dose escalation study in BALB/c mice to evaluate the maximum tolerated dose of redaporfin; and (ii) a safety toxicology study in Wistar rats, of a single dose of redaporfin, with or without illumination, to evaluate possible signs of systemic toxicity. Redaporfin formulation was well tolerated by mice, with no signs of adverse reactions up to 75 mg/kg. In rats, there were no relevant changes, except for a significant, but transient, increase in the blood serum markers for hepatic function and muscle integrity, and also on neutrophil counts, observed after the application of light. The overall results showed that redaporfin-PDT is very well tolerated. No abnormalities were observed, including reactions at the injection site or skin phototoxicity, although the animals were maintained in normal indoor lighting. Redaporfin also showed a high efficacy in the treatment of male BALB/c mice with subcutaneously implanted colon (CT26) tumours. Vascular-PDT with 1.5 mg/kg redaporfin and a light dose of 74 J/cm2 led to the complete tumour regression in 83% of the mice. PMID:26670231

Response of rat skin to boron neutron capture therapy with p-boronophenylalanine or borocaptate sodium.

PubMed

Morris, G M; Coderre, J A; Hopewell, J W; Micca, P L; Rezvani, M

1994-08-01

The effects of boron neutron capture irradiation employing either BPA or BSH as neutron capture agents has been assessed using the dorsal skin of Fischer 344 rats. Pharmacokinetic studies, using prompt gamma spectrometry, revealed comparable levels of boron-10 (10B) in blood and skin after the intravenous infusion of BSH (100 mg/kg body wt.). The 10B content of blood (12.0 +/- 0.5 micrograms/g) was slightly higher than that of skin (10.0 +/- 0.5 micrograms/g) after oral dosing with BPA. Biphasic skin reactions were observed after irradiation with the thermal neutron beam alone or in combination with BPA or BSH. The time of onset of the first phase of the skin reaction, moist desquamation, was approximately 2 weeks. The time at which the second-wave skin reaction, dermal necrosis, became evident was dose-related and occurred after a latent interval of > or = 24 weeks, well after the acute epithelial reaction had healed. The incidence of both phases of skin damage was also dose-related. The radiation doses required to produce skin damage in 50% of skin sites (ED50 values) were calculated from dose-effect curves and these values were used to determine relative biological effectiveness (RBE) and compound biological effectiveness (CBE) factors for both moist desquamation and dermal necrosis. It was concluded on the basis of these calculations that the microdistribution of the two neutron capture agents had a critical bearing on the overall biological effect after thermal neutron activation. BSH, which was possibly excluded from the cytoplasm of epidermal cells, had a low CBE factor value (0.56 +/- 0.06) while BPA, which may be selectively accumulated in epidermal cells had a very high CBE factor (3.74 +/- 0.7). For the dermal reaction, where vascular endothelial cells represent the likely target cell population, the CBE factor values were comparable, at 0.73 +/- 0.42 and 0.86 +/- 0.08 for BPA ad BSH, respectively.

Repair of UVB-damaged skin by the antioxidant sulphated flavone glycoside thalassiolin B isolated from the marine plant Thalassia testudinum Banks ex König.

PubMed

Regalado, Erik L; Rodríguez, María; Menéndez, Roberto; Concepción, Angel A; Nogueiras, Clara; Laguna, Abilio; Rodríguez, Armando A; Williams, David E; Lorenzo-Luaces, Patricia; Valdés, Olga; Hernandez, Yasnay

2009-01-01

Daily topical application of the aqueous ethanolic extract of the marine sea grass, Thalassia testudinum, on mice skin exposed to UVB radiation resulted in a dose-dependent recovery of the skin macroscopic alterations over a 6-day period. Maximal effect (90%) occurred at a dose of 240 microg/cm(2), with no additional effects at higher doses. Bioassay-guided fractionation of the plant extract resulted in the isolation of thalassiolin B (1). Topical application of 1 (240 microg/cm(2)) markedly reduces skin UVB-induced damage. In addition, thalassiolin B scavenged 2,2-diphenyl-2-picrylhydrazyl radical with an EC(50) = 100 microg/ml. These results suggest that thalassiolin B is responsible for the skin-regenerating effects of the crude extract of T. testudinum.

Drinking Water Arsenic Contamination, Skin Lesions, and Malignancies: A Systematic Review of the Global Evidence

PubMed Central

Karagas, Margaret R.; Gossai, Anala; Pierce, Brandon; Ahsan, Habibul

2015-01-01

Skin lesions and cancer are known manifestations of chronic exposure to arsenic contaminated drinking water. Epidemiologic data primarily comes from regions with exposures 1–2 orders of magnitude above the current World Health Organization (WHO)’s guidelines of 10 μg/L. Emerging evidence indicates that more common exposures may also be related to both non-cancerous and cancerous changes to the skin. In this review, we focus on the body of epidemiologic literature that encompasses exposures within the WHO guidelines, excluding studies that lacked individual exposure estimates and case reports. For skin lesions and skin cancers, 15 and 10 studies were identified that met our criteria, respectively. For skin lesions, a consistent dose-response relationship with water arsenic has been observed, with increased risk evident at low- to moderate-dose exposure. Of the larger studies of specific histologic types of skin cancers, although with differing exposure definitions, there was evidence of dose-related relationships with both basal cell carcinomas and squamous cell carcinomas. The effect of arsenic exposure on skin lesion risk is likely modified by genetic variants that influence arsenic metabolism. Accumulating evidence suggests that arsenic may increase risk of skin lesions and skin cancers at levels not previously considered harmful, and that genetic factors may influence risk. PMID:26231242

Drinking Water Arsenic Contamination, Skin Lesions, and Malignancies: A Systematic Review of the Global Evidence.

PubMed

Karagas, Margaret R; Gossai, Anala; Pierce, Brandon; Ahsan, Habibul

2015-03-01

Skin lesions and cancer are known manifestations of chronic exposure to arsenic contaminated drinking water. Epidemiologic data primarily comes from regions with exposures 1-2 orders of magnitude above the current World Health Organization (WHO) guidelines of 10 μg/L. Emerging evidence indicates that more common exposures may also be related to both noncancerous and cancerous changes to the skin. In this review, we focus on the body of epidemiologic literature that encompasses exposures within the WHO guidelines, excluding studies that lacked individual exposure estimates and case reports. For skin lesions and skin cancers, 15 and 10 studies were identified that met our criteria, respectively. For skin lesions, a consistent dose-response relationship with water arsenic has been observed, with increased risk evident at low- to moderate-dose exposure. Of the larger studies of specific histologic types of skin cancers, although with differing exposure definitions, there was evidence of dose-related relationships with both basal cell carcinomas and squamous cell carcinomas. The effect of arsenic exposure on skin lesion risk is likely modified by genetic variants that influence arsenic metabolism. Accumulating evidence suggests that arsenic may increase risk of skin lesions and skin cancers at levels not previously considered harmful, and that genetic factors may influence risk.

Progress report on hot particle studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baum, J.W.; Kaurin, D.G.; Waligorski, M.

1992-02-01

NCRP Report 106 on the effects of hot particles on the skin of pigs, monkeys, and humans was critically reviewed and reassessed. The analysis of the data of Forbes and Mikhail on the effects from activated UC{sub 2} particles, ranging in diameter from 144 {mu}m to 328 {mu}m, led to the formulation of a new model to predict both the threshold for acute ulceration and for ulcer diameter. In this model, a point dose of 27 Gy at a depth of 1.33 mm in tissue will cause an ulcer with a diameter determined by the radius to which this dosemore » extends. Application of the model to the Forbes and Mikhail data obtained with mixed fission product beta particles yielded a threshold'' (5% probability) of 6 {times} 10{sup 9} beta particles from a point source of high energy (2.25 MeV maximum) beta particles on skin. The above model was used to predict that approximately 1.2 {times} 10{sup 10} beta particles from Sr-Y-90 would produce similar effects, since few Sr-90 beta particles reach 1.33 mm depth. These emissions correspond to doses at 70-{mu}m depth in tissue of approximately 5.3 to 5.5 Gy averaged over 1 cm{sup 2}, respectively.« less

Progress report on hot particle studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baum, J.W.; Kaurin, D.G.; Waligorski, M.

1992-02-01

NCRP Report 106 on the effects of hot particles on the skin of pigs, monkeys, and humans was critically reviewed and reassessed. The analysis of the data of Forbes and Mikhail on the effects from activated UC{sub 2} particles, ranging in diameter from 144 {mu}m to 328 {mu}m, led to the formulation of a new model to predict both the threshold for acute ulceration and for ulcer diameter. In this model, a point dose of 27 Gy at a depth of 1.33 mm in tissue will cause an ulcer with a diameter determined by the radius to which this dosemore » extends. Application of the model to the Forbes and Mikhail data obtained with mixed fission product beta particles yielded a ``threshold`` (5% probability) of 6 {times} 10{sup 9} beta particles from a point source of high energy (2.25 MeV maximum) beta particles on skin. The above model was used to predict that approximately 1.2 {times} 10{sup 10} beta particles from Sr-Y-90 would produce similar effects, since few Sr-90 beta particles reach 1.33 mm depth. These emissions correspond to doses at 70-{mu}m depth in tissue of approximately 5.3 to 5.5 Gy averaged over 1 cm{sup 2}, respectively.« less

High dose rates obtained outside ISS in June 2015 during SEP event.

PubMed

Dachev, T P; Tomov, B T; Matviichuk, Yu N; Dimitrov, Pl G; Bankov, N G

2016-06-01

The R3DR2 instrument performed measurements in the European Space Agency (ESA) EXPOSE-R2 platform outside the Russian "Zvezda" module of the International Space Station (ISS) in the period 24 October 2014-11 January 2016. It is the Liulin-type deposited energy spectrometer (DES) (Dachev et al., 2015a). Took place in November 2014, this was the first attempt to monitor a small solar energetic particle (SEP) event outside ISS using the Liulin-type DES (Dachev et al., 2015d). In this study, we describe the dosimetric characteristics of the largest SEP event, observed on 22 June 2015 with the R3DR2 instrument outside ISS. The main finding of this study is that SEP protons with a minimum energy of approximately 7MeV at the surface of the R3DR2 detector produced high dose rates, reaching >5000µGyh(-1), while the inner radiation belt maximum dose was at the level of 2200µGyh(-1). If a virtual external vehicle activity (EVA) was performed in the same period of the SEP maximum on 22 June 2015, the doses obtained in the skin of cosmonauts/astronauts can reach 2.84mGy after 6.5h, which is similar to the average absorbed dose inside ISS for 15days (Reitz et al., 2005). A comparison with other extreme events measured with Liulin-type instruments shows that SEPs similar to that observed on 22 June 2015 could be one of the most dangerous events for the cosmonauts/astronauts involved in EVA. Copyright © 2016 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

Phase I safety, pharmacokinetic, and pharmacodynamic study of the thrombospondin-1-mimetic angiogenesis inhibitor ABT-510 in patients with advanced cancer.

PubMed

Hoekstra, Ronald; de Vos, Filip Y F L; Eskens, Ferry A L M; Gietema, Jourik A; van der Gaast, Ate; Groen, Harry J M; Knight, Raymond A; Carr, Robert A; Humerickhouse, Rod A; Verweij, Jaap; de Vries, Elisabeth G E

2005-08-01

ABT-510 is an angiogenesis inhibitor derived from thrombospondin-1, a naturally occurring inhibitor of angiogenesis. We investigated ABT-510, which was administered subcutaneously in patients with advanced solid malignancies, to assess safety, pharmacokinetics, and serum markers of angiogenesis. ABT-510 was administered subcutaneously as a continuous infusion (100 mg/24 h) and bolus injections (100, 200, and 260 mg once daily; 50 and 100 mg twice daily) in 28-day cycles. Thirty-nine patients received a total of 144 treatment cycles. Administration by continuous infusion was hampered by the onset of painful skin infiltrates at the injection site. In the bolus injection regimens, the most common toxicities observed were mild injection-site reactions and fatigue. Maximum-tolerated dose was not defined, but 260 mg was defined as the maximum clinically practical dose. ABT-510 pharmacokinetics were linear across the dosage ranges tested, and the potential therapeutic threshold (plasma concentrations > 100 ng/mL > 3 h/d) was achieved with all dose regimens. Median serum basic fibroblast growth factor (bFGF) levels decreased from 14.1 pg/mL (range, 0.5 to 77.7 pg/mL) at baseline to 3.2 pg/mL (range, 0.2 to 29.4 pg/mL) after 56 days of treatment (P = .003). No correlations with time on study or ABT-510 dose or exposure were observed for individual changes in bFGF. Stable disease lasting for six cycles or more was seen in six patients. ABT-510 demonstrated a favorable toxicity profile and linear and time-independent pharmacokinetics with biologically relevant plasma concentrations. The significant number of patients with prolonged stable disease and the convenient method of dosing merit further studies with this angiogenesis inhibitor.

Total skin electron irradiation: evaluation of dose uniformity throughout the skin surface.

PubMed

Anacak, Yavuz; Arican, Zumre; Bar-Deroma, Raquel; Tamir, Ada; Kuten, Abraham

2003-01-01

In this study, in vivo dosimetic data of 67 total skin electron irradiation (TSEI) treatments were analyzed. Thermoluminescent dosimetry (TLD) measurements were made at 10 different body points for every patient. The results demonstrated that the dose inhomogeneity throughout the skin surface is around 15%. The homogeneity was better at the trunk than at the extratrunk points, and was worse when a degrader was used. There was minimal improvement of homogeneity in subsequent days of treatment.

Comparison of skin dose measurement using nanoDot® dosimeter and machine readings of radiation dose during cardiac catheterization in children

PubMed Central

Balaguru, Duraisamy; Rodriguez, Matthew; Leon, Stephanie; Wagner, Louis K; Beasley, Charles W; Sultzer, Andrew; Numan, Mohammed T

2018-01-01

Objectives: Direct measurement of skin dose of radiation for children using optically stimulated luminescence (OSL) technology using nanoDot® (Landauer, Glenwood, IL, USA). Background: Radiation dose is estimated as cumulative air kerma (AK) and dosearea product based on standards established for adult size patients. Body size of pediatric patients who undergo cardiac catheterization for congenital heart disease vary widely from newborn to adolescence. Direct, skindose measurement applying OSL technology may eliminate errors in the estimate. Materials and Methods: The nanoDot® (1 cm × 1 cm × flat plastic cassette) is applied to patient's skin using adhesive tape during cardiac catheterization and radiation skin doses were read within 24 hrs. nanoDot® values were compared to the currently available cumulative AK values estimated and displayed on fluoroscopy monitor. Results: A total of 12 children were studied, aged 4 months to 18 years (median 1.1 years) and weight range 5.3–86 kg (median 8.4 kg). nanoDot® readings ranged from 2.58 mGy to 424.8 mGy (median 84.1 mGy). Cumulative AK ranged from 16.2 mGy to 571.2 mGy (median 171.1 mGy). Linear correlation was noted between nanoDot® values and AK values (R2 = 0.88, R = 0.94). nanoDot® readings were approximately 65% of the estimated cumulative AK estimated using the International Electrotechnical Commission standards. Conclusions: Application of OSL technology using nanoDot® provides an alternative to directly measure fluoroscopic skin dose in children during cardiac catheterization. Our data show that the actual skin dose for children is approximately one-third lower than the AK estimated using international standards for adult size patients. PMID:29440825

Comparison of skin dose measurement using nanoDot® dosimeter and machine readings of radiation dose during cardiac catheterization in children.

PubMed

Balaguru, Duraisamy; Rodriguez, Matthew; Leon, Stephanie; Wagner, Louis K; Beasley, Charles W; Sultzer, Andrew; Numan, Mohammed T

2018-01-01

Direct measurement of skin dose of radiation for children using optically stimulated luminescence (OSL) technology using nanoDot ® (Landauer, Glenwood, IL, USA). Radiation dose is estimated as cumulative air kerma (AK) and dosearea product based on standards established for adult size patients. Body size of pediatric patients who undergo cardiac catheterization for congenital heart disease vary widely from newborn to adolescence. Direct, skindose measurement applying OSL technology may eliminate errors in the estimate. The nanoDot ® (1 cm × 1 cm × flat plastic cassette) is applied to patient's skin using adhesive tape during cardiac catheterization and radiation skin doses were read within 24 hrs. nanoDot ® values were compared to the currently available cumulative AK values estimated and displayed on fluoroscopy monitor. A total of 12 children were studied, aged 4 months to 18 years (median 1.1 years) and weight range 5.3-86 kg (median 8.4 kg). nanoDot® readings ranged from 2.58 mGy to 424.8 mGy (median 84.1 mGy). Cumulative AK ranged from 16.2 mGy to 571.2 mGy (median 171.1 mGy). Linear correlation was noted between nanoDot® values and AK values ( R 2 = 0.88, R = 0.94). nanoDot® readings were approximately 65% of the estimated cumulative AK estimated using the International Electrotechnical Commission standards. Application of OSL technology using nanoDot® provides an alternative to directly measure fluoroscopic skin dose in children during cardiac catheterization. Our data show that the actual skin dose for children is approximately one-third lower than the AK estimated using international standards for adult size patients.

Poster — Thur Eve — 10: Partial kV CBCT, complete kV CBCT and EPID in breast treatment: a dose comparison study for skin, breasts, heart and lungs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roussin, E; Archambault, L K; Wierzbicki, W

The advantages of kilovoltage cone beam CT (kV CBCT) imaging over electronic portal imaging device (EPID) such as accurate 3D anatomy, soft tissue visualization, fast rigid registration and enhanced precision on patient positioning has lead to its increasing use in clinics. The benefits of this imaging technique are at the cost of increasing the dose to healthy surrounding organs. Our center has moved toward the use of daily partial rotation kV CBCT to restrict the dose to healthy tissues. This study aims to better quantify radiation doses from different image-guidance techniques such as tangential EPID, complete and partial kV CBCTmore » for breast treatments. Cross-calibrated ionization chambers and kV calibrated Gafchromic films were used to measure the dose to the heart, lungs, breasts and skin. It was found that performing partial kV CBCT decreases the heart dose by about 36%, the lungs dose by 31%, the contralateral breast dose by 41% and the ipsilateral breast dose by 43% when compared to a full rotation CBCT. The skin dose measured for a full rotation CBCT was about 0.8 cGy for the contralateral breast and about 0.3 cGy for the ipsilateral breast. The study is still ongoing and results on skin doses for partial rotation kV CBCT as well as for tangential EPID images are upcoming.« less

Radiation environment on the Mir orbital station during solar minimum.

PubMed

Badhwar, G D; Atwell, W; Cash, B; Petrov, V M; Akatov YuA; Tchernykh, I V; Shurshakov, V A; Arkhangelsky, V A

1998-01-01

The Mir station has been in a 51.65 degrees inclination orbit since March 1986. In March 1995, the first US astronaut flew on the Mir-18 mission and returned on the Space Shuttle in July 1995. Since then three additional US astronauts have stayed on orbit for up to 6 months. Since the return of the first US astronaut, both the Spektr and Priroda modules have docked with Mir station, altering the mass shielding distribution. Radiation measurements, including the direct comparison of US and Russian absorbed dose rates in the Base Block of the Mir station, were made during the Mir-18 and -19 missions. There is a significant variation of dose rates across the core module; the six locations sampled showed a variation of a factor of nearly two. A tissue equivalent proportional counter (TEPC) measured a total absorbed dose rate of 300 microGy/day, roughly equally divided between the rate due to trapped protons from the South Atlantic Anomaly (SAA) and galactic cosmic radiation (GCR). This dose rate is about a factor of two lower than the rate measured by the thinly shielded (0.5 g cm-2 of Al) operational ion chamber (R-16), and about 3/2 of the rate of the more heavily shielded (3.5 g cm-2 of Al) ion chamber. This is due to the differences in the mass shielding properties at the location of these detectors. A comparison of integral linear energy transfer (LET) spectra measured by TEPC and plastic nuclear track detectors (PNTDs) deployed side by side are in remarkable agreement in the LET region of 15-1000 keV/micrometer, where the PNTDs are fully efficient. The average quality factor, using the ICRP-26 definition, was 2.6, which is higher than normally used. There is excellent agreement between the measured GCR dose rate and model calculations, but this is not true for trapped protons. The measured Mir-18 crew skin dose equivalent rate was 1133 microSv/day. Using the skin dose rate and anatomical models, we have estimated the blood-forming organ (BFO) dose rate and the maximum stay time in orbit for International Space Station crew members.

ICI 182,780 penetrates brain and hypothalamic tissue and has functional effects in the brain after systemic dosing.

PubMed

Alfinito, Peter D; Chen, Xiaohong; Atherton, James; Cosmi, Scott; Deecher, Darlene C

2008-10-01

Previous reports suggest the antiestrogen ICI 182,780 (ICI) does not cross the blood-brain barrier (BBB). However, this hypothesis has never been directly tested. In the present study, we tested whether ICI crosses the BBB, penetrates into brain and hypothalamic tissues, and affects known neuroendocrine functions in ovariectomized rats. Using HPLC with mass spectrometry, ICI (1.0 mg/kg.d, 3 d) was detected in plasma and brain and hypothalamic tissues for up to 24 h with maximum concentrations of 43.1 ng/ml, and 31.6 and 38.8 ng/g, respectively. To evaluate antiestrogenic effects of ICI in the brain after systemic dosing, we tested its ability to block the effect of 17 alpha-ethinyl estradiol (EE) (0.3 mg/kg, 8 d) on tail-skin temperature abatement in the morphine-dependent model of hot flush and on body weight change. In the morphine-dependent model, EE abated 64% of the naloxone-induced tail-skin temperature increase. ICI pretreatment (1.0, 3.0 mg/kg.d) dose dependently inhibited this effect. ICI (3.0 mg/kg.d) alone showed estrogenic-like actions, abating 30% the naloxone-induced flush. In body weight studies, EE-treated rats weighed 58.5 g less than vehicle-treated rats after 8 d dosing. This effect was partially blocked by ICI (3.0 mg/kg.d) pretreatment. Similar to EE treatment, rats receiving 1.0 or 3.0 mg/kg.d ICI alone showed little weight gain compared with vehicle-treated controls. Thus, ICI crosses the BBB, penetrates into brain and hypothalamic tissues, and has both antiestrogenic and estrogenic-like actions on neuroendocrine-related functions.

Lack of phototoxicity potential with delafloxacin in healthy male and female subjects: comparison to lomefloxacin.

PubMed

Dawe, R S; Ferguson, J; Ibbotson, S; Lawrence, L; Paulson, S; Duffy, E; Cammarata, S

2018-05-03

Delafloxacin is a fluoroquinolone antibiotic recently approved by the FDA for treatment of acute bacterial skin and skin structure infections (ABSSSI). Delafloxacin was assessed for phototoxicity potential compared with a known phototoxic fluoroquinolone. A Phase 1, investigator-blind, placebo/active-controlled, randomized, parallel-group study was conducted in 52 healthy male and female volunteers who received 200 or 400 mg of oral delafloxacin, 400 mg oral lomefloxacin or placebo once daily for 6 days. This study evaluated the photosensitizing potential and possible wavelength dependency of delafloxacin by comparing the response of the skin to ultraviolet A (UVA), ultraviolet B (UVB) and visible radiation prior to and during administration of delafloxacin, lomefloxacin as a positive control, or placebo. Adverse events were monitored throughout the study. Forty-seven subjects completed six days of dosing, and no evidence of phototoxicity was seen with delafloxacin. Delafloxacin at 200 and 400 mg day-1 and placebo did not demonstrate differences in percent change from baseline in minimal erythema dose at all tested wavelengths (295-430 nm) by monochromator and solar simulator. Lomefloxacin, the positive control, had statistically significant differences (p < 0.05) at UVA wavelengths of 335 and 365 ± 30 nm 24 hours after radiation exposure (maximum response). The phototoxic index results were significantly higher for lomefloxacin at 335 nm and 365 nm compared to placebo and delafloxacin. 200 and 400 mg of delafloxacin administered for 6 days were well tolerated in healthy adult volunteers. Delafloxacin and placebo failed to demonstrate a phototoxic effect but lomefloxacin, the positive control, demonstrated moderate phototoxicity.

Effects of low-dose γ-rays on the embryonic development of mouse melanoblasts and melanocytes in the epidermis and hair bulbs.

PubMed

Hirobe, Tomohisa; Eguchi-Kasai, Kiyomi; Sugaya, Kimihiko; Murakami, Masahiro

2011-06-01

The effects of low-dose γ-rays on the embryonic development of animal cells are not well studied. The mouse melanocyte is a good model to study the effects of low-dose γ-rays on the development of animal cells, as it possesses visible pigment (melanin) as a differentiation marker. The aim of this study is to investigate in detail the effects of low-dose γ-rays on embryonic development of mouse melanoblasts and melanocytes in the epidermis and hair bulbs at cellular level. Pregnant females of C57BL/10J mice at nine days of gestation were whole-body irradiated with a single acute dose of γrays (0.1, 0.25, 0.5, and 0.75 Gy), and the effects of γ-rays were studied by scoring changes in the development of epidermal melanoblasts and melanocytes, hair follicles, and hair bulb melanocytes at 18 days in gestation. The number of epidermal melanoblasts and melanocytes, hair follicles, and hair bulb melanocytes in the dorsal and ventral skins was markedly decreased even at 0.1 Gy-treated embryos (P < 0.001), and gradually decreased as dose increased. The effects on the ventral skin were greater than those on the dorsal skin. The dramatic reduction in the number of melanocytes compared to melanoblasts was observed in the ventral skin, but not in the dorsal skin. These results suggest that low-dose γ-rays provoke the death of melanoblasts and melanocytes, or inhibit the proliferation and differentiation of melanoblasts and melanocytes, even at the low dose.

Poster - 07: Investigations of the Advanced Collapsed-cone Engine for HDR Brachytherapy Scalp Treatments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cawston-Grant, Brie; Morrison, Hali; Sloboda, Ron

Purpose: To present an investigation of the Advanced Collapsed-cone Engine (ACE) in Oncentraê Brachy (OcB) v4.5 using a tissue equivalent phantom modeling scalp brachytherapy (BT) treatments. Methods: A slab phantom modeling the skin, skull, brain and mold was used. A dose of 400cGy was prescribed to just above the skull layer using TG-43 and was delivered using an HDR afterloader. Measurements were made using Gafchromic™ EBT3 film at four depths within the phantom. The TG-43 planned and film measured doses were compared to the standard (sACE) and high (hACE) accuracy ACE options in OcB between the surface and below themore » skull. Results: The average difference between the TG-43 calculated and film measured doses was −11.25±3.38% when there was no air gap between the mold and skin; sACE and hACE doses were on average lower than TG-43 calculated doses by 3.41±0.03% and 2.45±0.03%, respectively. With a 3mm air gap between the mold and skin, the difference between the TG-43 calculated and measured doses was −8.28±5.76%; sACE and hACE calculations yielded average doses 1.87±0.03% and 1.78±0.04% greater than TG-43, respectively. Conclusions: TG-43, sACE, and hACE were found to overestimate doses below the skull layer compared to film. With a 3mm air gap between the mold and skin, sACE and hACE more accurately predicted the film dose to the skin surface than TG-43. More clinical variations and their implications are currently being investigated.« less

CEM43°C thermal dose thresholds: a potential guide for magnetic resonance radiofrequency exposure levels?

PubMed

van Rhoon, Gerard C; Samaras, Theodoros; Yarmolenko, Pavel S; Dewhirst, Mark W; Neufeld, Esra; Kuster, Niels

2013-08-01

To define thresholds of safe local temperature increases for MR equipment that exposes patients to radiofrequency fields of high intensities for long duration. These MR systems induce heterogeneous energy absorption patterns inside the body and can create localised hotspots with a risk of overheating. The MRI + EUREKA research consortium organised a "Thermal Workshop on RF Hotspots". The available literature on thresholds for thermal damage and the validity of the thermal dose (TD) model were discussed. The following global TD threshold guidelines for safe use of MR are proposed: 1. All persons: maximum local temperature of any tissue limited to 39 °C 2. Persons with compromised thermoregulation AND (a) Uncontrolled conditions: maximum local temperature limited to 39 °C (b) Controlled conditions: TD < 2 CEM43°C 3. Persons with uncompromised thermoregulation AND (a) Uncontrolled conditions: TD < 2 CEM43°C (b) Controlled conditions: TD < 9 CEM43°C The following definitions are applied: Controlled conditions A medical doctor or a dedicated trained person can respond instantly to heat-induced physiological stress Compromised thermoregulation All persons with impaired systemic or reduced local thermoregulation • Standard MRI can cause local heating by radiofrequency absorption. • Monitoring thermal dose (in units of CEM43°C) can control risk during MRI. • 9 CEM43°C seems an acceptable thermal dose threshold for most patients. • For skin, muscle, fat and bone,16 CEM43°C is likely acceptable.

Higher plasma quercetin levels following oral administration of an onion skin extract compared with pure quercetin dihydrate in humans.

PubMed

Burak, Constanze; Brüll, Verena; Langguth, Peter; Zimmermann, Benno F; Stoffel-Wagner, Birgit; Sausen, Udo; Stehle, Peter; Wolffram, Siegfried; Egert, Sarah

2017-02-01

To investigate the plasma kinetics of quercetin derived from hard capsules filled with onion skin extract powder or quercetin dihydrate in humans. In a randomized, single-blind, diet-controlled crossover study, 12 healthy subjects (six men and six women) aged 21-33 years were administered a single oral supra-nutritional dose of approximately 163 mg quercetin derived from onion skin extract powder (containing 95.3 % of total flavonoids as quercetin aglycone) or quercetin dihydrate (134 mg quercetin aglycone equivalent). Blood samples were collected before and during a 24-h period after quercetin administration. The concentrations of quercetin and its two monomethylated derivatives, isorhamnetin (3'-O-methyl quercetin), and tamarixetin (4'-O-methyl quercetin), were measured using HPLC with fluorescence detection after plasma enzymatic treatment. The systemic availability, determined by comparing the plasma concentration-time curves of quercetin, was 4.8 times higher, and the maximum plasma concentration (C max ) was 5.4 times higher after ingestion of the onion skin extract than after ingestion of pure quercetin dihydrate. By contrast, t max did not differ significantly between the two formulations. The C max values for isorhamnetin and tamarixetin were 3.8 and 4.4 times higher, respectively, after administration of onion skin extract than after pure quercetin dihydrate. The plasma kinetics of quercetin were not significantly different in men and women. Quercetin aglycone derived from onion skin extract powder is significantly more bioavailable than that from quercetin dihydrate powder filled hard capsules.

In vitro dose measurements in a human cadaver with abdomen/pelvis CT scans

PubMed Central

Zhang, Da; Padole, Atul; Li, Xinhua; Singh, Sarabjeet; Khawaja, Ranish Deedar Ali; Lira, Diego; Liu, Tianyu; Shi, Jim Q.; Otrakji, Alexi; Kalra, Mannudeep K.; Xu, X. George; Liu, Bob

2014-01-01

Purpose: To present a study of radiation dose measurements with a human cadaver scanned on a clinical CT scanner. Methods: Multiple point dose measurements were obtained with high-accuracy Thimble ionization chambers placed inside the stomach, liver, paravertebral gutter, ascending colon, left kidney, and urinary bladder of a human cadaver (183 cm in height and 67.5 kg in weight) whose abdomen/pelvis region was scanned repeatedly with a multidetector row CT. The flat energy response and precision of the dosimeters were verified, and the slight differences in each dosimeter's response were evaluated and corrected to attain high accuracy. In addition, skin doses were measured for radiosensitive organs outside the scanned region with OSL dosimeters: the right eye, thyroid, both nipples, and the right testicle. Three scan protocols were used, which shared most scan parameters but had different kVp and mA settings: 120-kVp automA, 120-kVp 300 mA, and 100-kVp 300 mA. For each protocol three repeated scans were performed. Results: The tube starting angle (TSA) was found to randomly vary around two major conditions, which caused large fluctuations in the repeated point dose measurements: for the 120-kVp 300 mA protocol this angle changed from approximately 110° to 290°, and caused 8% − 25% difference in the point dose measured at the stomach, liver, colon, and urinary bladder. When the fluctuations of the TSA were small (within 5°), the maximum coefficient of variance was approximately 3.3%. The soft tissue absorbed doses averaged from four locations near the center of the scanned region were 27.2 ± 3.3 and 16.5 ± 2.7 mGy for the 120 and 100-kVp fixed-mA scans, respectively. These values were consistent with the corresponding size specific dose estimates within 4%. The comparison of the per-100-mAs tissue doses from the three protocols revealed that: (1) dose levels at nonsuperficial locations in the TCM scans could not be accurately deduced by simply scaling the fix-mA doses with local mA values; (2) the general power law relationship between dose and kVp varied from location to location, with the power index ranged between 2.7 and 3.5. The averaged dose measurements at both nipples, which were about 0.6 cm outside the prescribed scan region, ranged from 23 to 27 mGy at the left nipple, and varied from 3 to 20 mGy at the right nipple over the three scan protocols. Large fluctuations over repeated scans were also observed, as a combined result of helical scans of large pitch (1.375) and small active areas of the skin dosimeters. In addition, the averaged skin dose fell off drastically with the distance to the nearest boundary of the scanned region. Conclusions: This study revealed the complexity of CT dose fluctuation and variation with a human cadaver. PMID:25186398

Skin penetration and kinetics of pristine fullerenes (C{sub 60}) topically exposed in industrial organic solvents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xia, Xin R., E-mail: xia@ncsu.ed; Monteiro-Riviere, Nancy A.; Riviere, Jim E.

2010-01-01

Pristine fullerenes (C{sub 60}) in different solvents will be used in many industrial and pharmaceutical manufacturing and derivatizing processes. This report explores the impact of solvents on skin penetration of C{sub 60} from different types of industrial solvents (toluene, cyclohexane, chloroform and mineral oil). Yorkshire weanling pigs (n = 3) were topically dosed with 500 muL of 200 mug/mL C{sub 60} in a given solvent for 24 h and re-dosed daily for 4 days to simulate the worst scenario in occupational exposures. The dose sites were tape-stripped and skin biopsies were taken after 26 tape-strips for quantitative analysis. When dosedmore » in toluene, cyclohexane or chloroform, pristine fullerenes penetrated deeply into the stratum corneum, the primary barrier of skin. More C{sub 60} was detected in the stratum corneum when dosed in chloroform compared to toluene or cyclohexane. Fullerenes were not detected in the skin when dosed in mineral oil. This is the first direct evidence of solvent effects on the skin penetration of pristine fullerenes. The penetration of C{sub 60} into the stratum corneum was verified using isolated stratum corneum in vitro; the solvent effects on the stratum corneum absorption of C{sub 60} were consistent with those observed in vivo. In vitro flow-through diffusion cell experiments were conducted in pig skin and fullerenes were not detected in the receptor solutions by 24 h. The limit of detection was 0.001 mug/mL of fullerenes in 2 mL of the receptor solutions.« less

Monte Carlo investigation of backscatter factors for skin dose determination in interventional neuroradiology procedures

NASA Astrophysics Data System (ADS)

Omar, Artur; Benmakhlouf, Hamza; Marteinsdottir, Maria; Bujila, Robert; Nowik, Patrik; Andreo, Pedro

2014-03-01

Complex interventional and diagnostic x-ray angiographic (XA) procedures may yield patient skin doses exceeding the threshold for radiation induced skin injuries. Skin dose is conventionally determined by converting the incident air kerma free-in-air into entrance surface air kerma, a process that requires the use of backscatter factors. Subsequently, the entrance surface air kerma is converted into skin kerma using mass energy-absorption coefficient ratios tissue-to-air, which for the photon energies used in XA is identical to the skin dose. The purpose of this work was to investigate how the cranial bone affects backscatter factors for the dosimetry of interventional neuroradiology procedures. The PENELOPE Monte Carlo system was used to calculate backscatter factors at the entrance surface of a spherical and a cubic water phantom that includes a cranial bone layer. The simulations were performed for different clinical x-ray spectra, field sizes, and thicknesses of the bone layer. The results show a reduction of up to 15% when a cranial bone layer is included in the simulations, compared with conventional backscatter factors calculated for a homogeneous water phantom. The reduction increases for thicker bone layers, softer incident beam qualities, and larger field sizes, indicating that, due to the increased photoelectric crosssection of cranial bone compared to water, the bone layer acts primarily as an absorber of low-energy photons. For neurointerventional radiology procedures, backscatter factors calculated at the entrance surface of a water phantom containing a cranial bone layer increase the accuracy of the skin dose determination.

Effect of nano-silver hydrogel coating film on deep partial thickness scald model of rabbit.

PubMed

Xi, Peng; Li, Yan; Ge, Xiaojin; Liu, Dandan; Miao, Mingsan

2018-05-01

Observing the effect of nano-silver hydrogel coating film on deep partial thickness scald model of rabbit. We prepared boiling water scalded rabbits with deep II degree scald models and applied high, medium and low doses of nano-silver hydrogel coating film for different time and area. Then we compared the difference of burned paper weight before administration and after administration model burns, burn local skin irritation points infection, skin crusting and scabs from the time, and the impact of local skin tissue morphology. Rabbits deep II degree burn model successful modeling; on day 12, 18, high, medium and low doses of nano-silver hydrogel coating film significantly reduced skin irritation of rabbits infected with the integral value ( P  < 0.01, P  < 0.05); high, medium and low doses of nano-silver hydrogel coating film group significantly decreased skin irritation, infection integral value ( P  < 0.01, P  < 0.05); high, medium and low doses of nano-silver hydrogel coating film significantly reduced film rabbits' scalded skin crusting time ( P  < 0.01), significantly shortened the rabbit skin burns from the scab time ( P  < 0.01), and significantly improved the treatment of skin diseases in rabbits scald model change ( P  < 0.01, P  < 0.05). The nano-silver hydrogel coating film on the deep partial thickness burns has a significant therapeutic effect; external use has a significant role in wound healing.

NOTE: Clinical application of a OneDose™ MOSFET for skin dose measurements during internal mammary chain irradiation with high dose rate brachytherapy in carcinoma of the breast

NASA Astrophysics Data System (ADS)

Kinhikar, Rajesh A.; Sharma, Pramod K.; Tambe, Chandrashekhar M.; Mahantshetty, Umesh M.; Sarin, Rajiv; Deshpande, Deepak D.; Shrivastava, Shyam K.

2006-07-01

In our earlier study, we experimentally evaluated the characteristics of a newly designed metal oxide semiconductor field effect transistor (MOSFET) OneDose™ in-vivo dosimetry system for Ir-192 (380 keV) energy and the results were compared with thermoluminescent dosimeters (TLDs). We have now extended the same study to the clinical application of this MOSFET as an in-vivo dosimetry system. The MOSFET was used during high dose rate brachytherapy (HDRBT) of internal mammary chain (IMC) irradiation for a carcinoma of the breast. The aim of this study was to measure the skin dose during IMC irradiation with a MOSFET and a TLD and compare it with the calculated dose with a treatment planning system (TPS). The skin dose was measured for ten patients. All the patients' treatment was planned on a PLATO treatment planning system. TLD measurements were performed to compare the accuracy of the measured results from the MOSFET. The mean doses measured with the MOSFET and the TLD were identical (0.5392 Gy, 15.85% of the prescribed dose). The mean dose was overestimated by the TPS and was 0.5923 Gy (17.42% of the prescribed dose). The TPS overestimated the skin dose by 9% as verified by the MOSFET and TLD. The MOSFET provides adequate in-vivo dosimetry for HDRBT. Immediate readout after irradiation, small size, permanent storage of dose and ease of use make the MOSFET a viable alternative for TLDs.

Porcine skin damage thresholds for pulsed nanosecond-scale laser exposure at 1064-nm

NASA Astrophysics Data System (ADS)

DeLisi, Michael P.; Peterson, Amanda M.; Noojin, Gary D.; Shingledecker, Aurora D.; Tijerina, Amanda J.; Boretsky, Adam R.; Schmidt, Morgan S.; Kumru, Semih S.; Thomas, Robert J.

2018-02-01

Pulsed high-energy lasers operating in the near-infrared (NIR) band are increasingly being used in medical, industrial, and military applications, but there are little available experimental data to characterize their hazardous effects on skin tissue. The current American National Standard for the Safe Use of Lasers (ANSI Z136.1-2014) defines the maximum permissible exposure (MPE) on the skin as either a single-pulse or total exposure time limit. This study determined the minimum visible lesion (MVL) damage thresholds in Yucatan miniature pig skin for the single-pulse case and several multiple-pulse cases over a wide range of pulse repetition frequencies (PRFs) (10, 125, 2,000, and 10,000 Hz) utilizing nanosecond-scale pulses (10 or 60 ns). The thresholds are expressed in terms of the median effective dose (ED50) based on varying individual pulse energy with other laser parameters held constant. The results confirm a decrease in MVL threshold as PRF increases for exposures with a constant number of pulses, while also noting a PRF-dependent change in the threshold as a function of the number of pulses. Furthermore, this study highlights a change in damage mechanism to the skin from melanin-mediated photomechanical events at high irradiance levels and few numbers of pulses to bulk tissue photothermal additivity at lower irradiance levels and greater numbers of pulses. The observed trends exceeded the existing exposure limits by an average factor of 9.1 in the photothermally-damaged cases and 3.6 in the photomechanicallydamaged cases.

The skin: its structure and response to ionizing radiation.

PubMed

Hopewell, J W

1990-04-01

The response of the skin to ionizing radiation has important implications both for the treatment of malignant disease by radiation and for radiological protection. The structural organization of human skin is described and compared with that of the pig, with which it shows many similarities, in order that the response of the skin to ionizing radiation may be more fully understood. Acute radiation damage to the skin is primarily a consequence of changes in the epidermis; the timing of the peak of the reaction is related to the kinetic organization of this layer. The rate of development of damage is independent of the radiation dose, since this is related to the natural rate of loss of cells from the basal layer of the epidermis. Recovery of the epidermis occurs as a result of the proliferation of surviving clonogenic basal cells from within the irradiated area. The presence of clonogenic cells in the canal of the hair follicle is important, particularly after non-uniform irradiation from intermediate energy beta-emitters. The migration of viable cells from the edges of the irradiated site is also significant when small areas of skin are irradiated. Late damage to the skin is primarily a function of radiation effects on the vasculature; this produces a wave of dermal atrophy after 16-26 weeks. Dermal necrosis develops at this time after high doses. A second phase of dermal thinning is seen to develop after greater than 52 weeks, and this later phase of damage is associated with the appearance of telangiectasia. Highly localized irradiation of the skin, either to a specific layer (as may result from exposure to very low energy beta-emitters) or after exposure to small highly radioactive particles, 'hot particles', produces gross effects that become visibly manifest within 2 weeks of exposure. These changes result from the direct killing of the cells of the skin in interphase after doses greater than 100 Gy. Dose-effect curves have been established for the majority of these deterministic endpoints in the skin from the results of both experimental and clinical studies. These are of value in the establishment of safe radiation dose limits for the skin.

Risk of Skin Cancer from Space Radiation. Chapter 11

NASA Technical Reports Server (NTRS)

Cucinotta, Francis A.; Kim, Myung-Hee Y.; George, Kerry A.; Wu, Hong-Lu

2003-01-01

We review the methods for estimating the probability of increased incidence of skin cancers from space radiation exposure, and describe some of the individual factors that may contribute to risk projection models, including skin pigment, and synergistic effects of combined ionizing and UV exposure. The steep dose gradients from trapped electrons, protons, and heavy ions radiation during EVA and limitations in EVA dosimetry are important factors for projecting skin cancer risk of astronauts. We estimate that the probability of increased skin cancer risk varies more than 10-fold for individual astronauts and that the risk of skin cancer could exceed 1 % for future lunar base operations for astronauts with light skin color and hair. Limitations in physical dosimetry in estimating the distribution of dose at the skin suggest that new biodosimetry methods be developed for responding to accidental overexposure of the skin during future space missions.

Evaluating the effects of pentoxifylline administration on experimental pressure sores in rats by biomechanical examinations

PubMed Central

Velaei, Kobra; Torkman, Giti; Rezaie, Fatemealsadat; Amini, Abdollah; Noruzian, Mohsen; Tavassol, Azaedh; Bayat, Mehernoush

2012-01-01

This study used a biomechanical test to evaluate the effects of pentoxifylline administration on the wound healing process of an experimental pressure sore induced in rats. Under general anesthesia and sterile conditions, experimental pressure sores generated by no. 25 Halsted mosquito forceps were inflicted on 12 adult male rats. Pentoxifylline was injected intraperitoneally at a dose of 50 mg/kg daily from the day the pressure sore was generated, for a period of 20 days. At the end of 20 days, rats were sacrificed and skin samples extracted. Samples were biomechanically examined by a material testing instrument for maximum stress (N mm2), work up to maximum force (N), and elastic stiffness (N/mm). In the experimental group, maximum stress (2.05±0.15) and work up to maximum force (N/mm) (63.75±4.97) were significantly higher than the control group (1.3±0.27 and 43.3±14.96, P=0.002 and P=0.035, respectively). Pentoxifylline administration significantly accelerated the wound healing process in experimental rats with pressure sores, compared to that of the control group. PMID:23091522

Evaluating the effects of pentoxifylline administration on experimental pressure sores in rats by biomechanical examinations.

PubMed

Velaei, Kobra; Bayat, Mohammad; Torkman, Giti; Rezaie, Fatemealsadat; Amini, Abdollah; Noruzian, Mohsen; Tavassol, Azaedh; Bayat, Mehernoush

2012-09-01

This study used a biomechanical test to evaluate the effects of pentoxifylline administration on the wound healing process of an experimental pressure sore induced in rats. Under general anesthesia and sterile conditions, experimental pressure sores generated by no. 25 Halsted mosquito forceps were inflicted on 12 adult male rats. Pentoxifylline was injected intraperitoneally at a dose of 50 mg/kg daily from the day the pressure sore was generated, for a period of 20 days. At the end of 20 days, rats were sacrificed and skin samples extracted. Samples were biomechanically examined by a material testing instrument for maximum stress (N mm(2)), work up to maximum force (N), and elastic stiffness (N/mm). In the experimental group, maximum stress (2.05±0.15) and work up to maximum force (N/mm) (63.75±4.97) were significantly higher than the control group (1.3±0.27 and 43.3±14.96, P=0.002 and P=0.035, respectively). Pentoxifylline administration significantly accelerated the wound healing process in experimental rats with pressure sores, compared to that of the control group.

Assessing patient dose in interventional fluoroscopy using patient-dependent hybrid phantoms

NASA Astrophysics Data System (ADS)

Johnson, Perry Barnett

Interventional fluoroscopy uses ionizing radiation to guide small instruments through blood vessels or other body pathways to sites of clinical interest. The technique represents a tremendous advantage over invasive surgical procedures, as it requires only a small incision, thus reducing the risk of infection and providing for shorter recovery times. The growing use and increasing complexity of interventional procedures, however, has resulted in public health concerns regarding radiation exposures, particularly with respect to localized skin dose. Tracking and documenting patient-specific skin and internal organ dose has been specifically identified for interventional fluoroscopy where extended irradiation times, multiple projections, and repeat procedures can lead to some of the largest doses encountered in radiology. Furthermore, inprocedure knowledge of localized skin doses can be of significant clinical importance to managing patient risk and in training radiology residents. In this dissertation, a framework is presented for monitoring the radiation dose delivered to patients undergoing interventional procedures. The framework is built around two key points, developing better anthropomorphic models, and designing clinically relevant software systems for dose estimation. To begin, a library of 50 hybrid patient-dependent computational phantoms was developed based on the UF hybrid male and female reference phantoms. These phantoms represent a different type of anthropomorphic model whereby anthropometric parameters from an individual patient are used during phantom selection. The patient-dependent library was first validated and then used in two patient-phantom matching studies focused on cumulative organ and local skin dose. In terms of organ dose, patient-phantom matching was shown most beneficial for estimating the dose to large patients where error associated with soft tissue attenuation differences could be minimized. For small patients, inherent difference in organ size and location limited the effectiveness of matching. For skin dose, patient-phantom matching was found most beneficial for estimating the dose during lateral and anterior-posterior projections. Patient-sculpting of the patient.s outer body contour was also investigated for use during skin dose estimation and highlighted as a substantial step towards better patient-specificity. In order to utilize the models for actual patient dosimetry, two programs were developed based on the newly released Radiation Dose Structured Report (RDSR). The first program allows for the visualization of skin dose by translating the reference point air kerma to the location of the patient.s skin characterized by a computational model. The program represents an innovative tool that can be used by the interventional physician to modify behavior when clinically appropriate. The second program operates by automatically generating an input file from the RDSR which can then be run within a Monte Carlo based radiation transport code. The program has great potential for initiating and promoting the concept of 'cloud dosimetry', where patient-specific radiation transport is performed off-site and returned via the internet. Both programs are non-proprietary and transferable, and also incorporate the most advanced computational phantoms developed to date. Using the tools developed in this work, there exist a tangible opportunity to improve patient care with the end goal being a better understanding of the risk/benefit relationship that accompanies the medical use of ionizing radiation.

SU-F-T-517: Determining the Tissue Equivalence of a Brass Mesh Bolus in a Reconstructed Chest Wall Irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shekel, E; Epstein, D; Levin, D

2016-06-15

Purpose: To determine the tissue equivalence of a brass mesh bolus (RPD) in the setting of a reconstructed chest wall irradiation Methods: We measured breast skin dose delivered by a tangential field plan on an anthropomorphic phantom using Mosfet and nanoDot (Landauer) dosimeters in five different locations on the breast. We also measured skin dose using no bolus, 5mm and 10 mm superflab bolus. In the Eclipse treatment planning system (Varian, Palo Alto, CA) we calculated skin dose for different bolus thicknesses, ranging from 0 to 10 mm, in order to evaluate which calculation best matches the brass mesh measurements,more » as the brass mesh cannot be simulated due to artefacts.Finally, we measured depth dose behavior with the brass mesh bolus to verify that the bolus does not affect the dose to the breast itself beyond the build-up region. Results: Mosfet and nanoDot measurements were consistent with each other.As expected, skin dose measurements with no bolus had the least agreement with Eclipse calculation, while measurements for 5 and 10 mm agreed well with the calculation despite the difficulty in conforming superflab bolus to the breast contour. For the brass mesh the best agreement was for 3 mm bolus Eclipse calculation. For Mosfets, the average measurement was 90.8% of the expected dose, and for nanoDots 88.33% compared to 83.34%, 88.64% and 93.94% (2,3 and 5 mm bolus calculation respectively).The brass mesh bolus increased skin dose by approximately 25% but there was no dose increase beyond the build-up region. Conclusion: Brass mesh bolus is most equivalent to a 3 mm bolus, and does not affect the dose beyond the build-up region. The brass mesh cannot be directly calculated in Eclipse, hence a 3mm bolus calculation is a good reflection of the dose response to the brass mesh bolus.« less

SU-F-T-81: Treating Nose Skin Using Energy and Intensity Modulated Electron Beams with Monte Carlo Based Dose Calculation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, L; Fan, J; Eldib, A

Purpose: Treating nose skin with an electron beam is of a substantial challenge due to uneven nose surfaces and tissue heterogeneity, and consequently could have a great uncertainty of dose accuracy on the target. This work explored the method using Monte Carlo (MC)-based energy and intensity modulated electron radiotherapy (MERT), which would be delivered with a photon MLC in a standard medical linac (Artiste). Methods: The traditional treatment on the nose skin involves the usage of a bolus, often with a single energy electron beam. This work avoided using the bolus, and utilized mixed energies of electron beams. An in-housemore » developed Monte Carlo (MC)-based dose calculation/optimization planning system was employed for treatment planning. Phase space data (6, 9, 12 and 15 MeV) were used as an input source for MC dose calculations for the linac. To reduce the scatter-caused penumbra, a short SSD (61 cm) was used. A clinical case of the nose skin, which was previously treated with a single 9 MeV electron beam, was replanned with the MERT method. The resultant dose distributions were compared with the plan previously clinically used. The dose volume histogram of the MERT plan is calculated to examine the coverage of the planning target volume (PTV) and critical structure doses. Results: The target coverage and conformality in the MERT plan are improved as compared to the conventional plan. The MERT can provide more sufficient target coverage and less normal tissue dose underneath the nose skin. Conclusion: Compared to the conventional treatment technique, using MERT for the nose skin treatment has shown the dosimetric advantages in the PTV coverage and conformality. In addition, this technique eliminates the necessity of the cutout and bolus, which makes the treatment more efficient and accurate.« less

Temporal aspects of tumorigenic response to individual and mixed carcinogens. [Response of mouse skin to benzo(a)pyrene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albert, R.E.; Burns, F.J.

1976-02-01

Results are reported from experiments that involved either single or multiple doses of benzo(a)pyrene in mouse skin followed by prolonged observation. Preliminary results indicate linearity in dose and time and no evidence of recovery or enhancement for multiple doses of initiator given for extended periods of time. (auth)

In Vivo Dosimetry for Single-Fraction Targeted Intraoperative Radiotherapy (TARGIT) for Breast Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eaton, David J., E-mail: davideaton@nhs.net; Best, Bronagh; Brew-Graves, Chris

Purpose: In vivo dosimetry provides an independent check of delivered dose and gives confidence in the introduction or consistency of radiotherapy techniques. Single-fraction intraoperative radiotherapy of the breast can be performed with the Intrabeam compact, mobile 50 kV x-ray source (Carl Zeiss Surgical, Oberkochen, Germany). Thermoluminescent dosimeters (TLDs) can be used to estimate skin doses during these treatments. Methods and Materials: Measurements of skin doses were taken using TLDs for 72 patients over 3 years of clinical treatments. Phantom studies were also undertaken to assess the uncertainties resulting from changes in beam quality and backscatter conditions in vivo. Results: Themore » mean measured skin dose was 2.9 {+-} 1.6 Gy, with 11% of readings higher than the prescription dose of 6 Gy, but none of these patients showed increased complications. Uncertainties due to beam hardening and backscatter reduction were small compared with overall accuracy. Conclusions: TLDs are a useful and effective method to measure in vivo skin doses in intraoperative radiotherapy and are recommended for the initial validation or any modification to the delivery of this technique. They are also an effective tool to show consistent and safe delivery on a more frequent basis or to determine doses to other critical structures as required.« less

In vitro dose measurements in a human cadaver with abdomen/pelvis CT scans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Da; Padole, Atul; Li, Xinhua

2014-09-15

Purpose: To present a study of radiation dose measurements with a human cadaver scanned on a clinical CT scanner. Methods: Multiple point dose measurements were obtained with high-accuracy Thimble ionization chambers placed inside the stomach, liver, paravertebral gutter, ascending colon, left kidney, and urinary bladder of a human cadaver (183 cm in height and 67.5 kg in weight) whose abdomen/pelvis region was scanned repeatedly with a multidetector row CT. The flat energy response and precision of the dosimeters were verified, and the slight differences in each dosimeter's response were evaluated and corrected to attain high accuracy. In addition, skin dosesmore » were measured for radiosensitive organs outside the scanned region with OSL dosimeters: the right eye, thyroid, both nipples, and the right testicle. Three scan protocols were used, which shared most scan parameters but had different kVp and mA settings: 120-kVp automA, 120-kVp 300 mA, and 100-kVp 300 mA. For each protocol three repeated scans were performed. Results: The tube starting angle (TSA) was found to randomly vary around two major conditions, which caused large fluctuations in the repeated point dose measurements: for the 120-kVp 300 mA protocol this angle changed from approximately 110° to 290°, and caused 8% − 25% difference in the point dose measured at the stomach, liver, colon, and urinary bladder. When the fluctuations of the TSA were small (within 5°), the maximum coefficient of variance was approximately 3.3%. The soft tissue absorbed doses averaged from four locations near the center of the scanned region were 27.2 ± 3.3 and 16.5 ± 2.7 mGy for the 120 and 100-kVp fixed-mA scans, respectively. These values were consistent with the corresponding size specific dose estimates within 4%. The comparison of the per-100-mAs tissue doses from the three protocols revealed that: (1) dose levels at nonsuperficial locations in the TCM scans could not be accurately deduced by simply scaling the fix-mA doses with local mA values; (2) the general power law relationship between dose and kVp varied from location to location, with the power index ranged between 2.7 and 3.5. The averaged dose measurements at both nipples, which were about 0.6 cm outside the prescribed scan region, ranged from 23 to 27 mGy at the left nipple, and varied from 3 to 20 mGy at the right nipple over the three scan protocols. Large fluctuations over repeated scans were also observed, as a combined result of helical scans of large pitch (1.375) and small active areas of the skin dosimeters. In addition, the averaged skin dose fell off drastically with the distance to the nearest boundary of the scanned region. Conclusions: This study revealed the complexity of CT dose fluctuation and variation with a human cadaver.« less

SU-E-I-22: Dependence On Calibration Phantom and Field Area of the Conversion Factor Used to Calculate Skin Dose During Neuro-Interventional Fluoroscopic Procedures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rana, V K; Vijayan, S; Rudin, S R

Purpose: To determine the appropriate calibration factor to use when calculating skin dose with our real-time dose-tracking system (DTS) during neuro-interventional fluoroscopic procedures by evaluating the difference in backscatter from different phantoms and as a function of entrance-skin field area. Methods: We developed a dose-tracking system to calculate and graphically display the cumulative skin-dose distribution in real time. To calibrate the DTS for neuro-interventional procedures, a phantom is needed that closely approximates the scattering properties of the head. We compared the x-ray backscatter from eight phantoms: 20-cm-thick solid water, 16-cm diameter water-filled container, 16-cm CTDI phantom, modified-ANSI head phantom, 20-cm-thickmore » PMMA, Kyoto-Kagaku PBU- 50 head, Phantom-Labs SK-150 head, and RSD RS-240T head. The phantoms were placed on the patient table with the entrance surface at 15 cm tube-side from the isocenter of a Toshiba Infinix C-arm, and the entrance-skin exposure was measured with a calibrated 6-cc PTW ionization chamber. The measurement included primary radiation, backscatter from the phantom and forward scatter from the table and pad. The variation in entrance-skin exposure was also measured as a function of the skin-entrance area for a 30x30 cm by 20-cm-thick PMMA phantom and the SK-150 head phantom using four different added beam filters. Results: The entranceskin exposure values measured for eight different phantoms differed by up to 12%, while the ratio of entrance exposure of all phantoms relative to solid water showed less than 3% variation with kVp. The change in entrance-skin exposure with entrance-skin area was found to differ for the SK-150 head compared to the 20-cm PMMA phantom and the variation with field area was dependent on the added beam filtration. Conclusion: To accurately calculate skin dose for neuro-interventional procedures with the DTS, the phantom for calibration should be carefully chosen since different phantoms can contribute different backscatter for identical exposure parameters. Research supported in part by Toshiba Medical Systems and NIH Grants R43FD0158401, R44FD0158402 and R01EB002873.« less

Cetuximab-induced skin exanthema: prophylactic and reactive skin therapy are equally effective.

PubMed

Wehler, Thomas C; Graf, Claudine; Möhler, Markus; Herzog, Jutta; Berger, Martin R; Gockel, Ines; Lang, Hauke; Theobald, Matthias; Galle, Peter R; Schimanski, Carl C

2013-10-01

Treatment with cetuximab is accompanied by the development of an acneiform follicular skin exanthema in more than 80 % of patients. Severe exanthema (grade III/IV) develops in about 9-19 % of patients with the necessity of cetuximab dose reduction or cessation. The study presented was a retrospective analysis of 50 gastrointestinal cancer patients treated with cetuximab in combination with either FOLFIRI or FOLFOX. One cohort of 15 patients received an in-house reactive skin protocol upon development of an exanthema. A second cohort of 15 patients received a skin prophylaxis starting with the first dose of cetuximab before clinical signs of toxicity. A third historic group of 20 patients had received no skin prophylaxis or reactive treatment. 19/20 patients of the historic group developed a skin exanthema. Grade III/IV exanthema was observed six times. Forty percent discontinued cetuximab therapy. The average time to exanthema onset was 14.7 days. Applying the reactive skin protocol after the first occurrence of an exanthema, the exanthema was downgraded as follows: No patients developed grade IV° exanthema, and two patients developed a grade II/III exanthema. In the majority of cases, the reactive skin protocol controlled the exanthema (grade 0-I°). No dose reductions in cetuximab were necessary. Applying the prophylactic skin protocol starting at the beginning of cetuximab application was not superior to the reactive skin protocol. Cetuximab-induced skin exanthema can be coped with a reactive protocol equally effective as compared to a prophylactic skin treatment. A prospective study with higher patient numbers is planned.

Effect of the thermoplastic masks on dose distribution in the build-up region for photon beams

NASA Astrophysics Data System (ADS)

Półtorak, Michał; Fujak, Edyta; Kukołowicz, Paweł

2016-03-01

The aim of the study was to investigate the influence of thermoplastic masks material (Klarity Medical&Equipment Co., Guangzhou, China) with different diameters of holes (ϕ 0.25 cm and ϕ 0.40 cm) on the dose distribution in the build-up region for photon beams. Measurements were made for external radiation beams produced by the linear accelerator (TrueBeam, Varian Medical Systems, Inc., Palo Alto, CA, USA) using the Markus parallel plane ionization chamber and the Unidos electrometer (both from PTW, Freiburg, Germany). Measurements were made in a solid water phantom for two photon energies 6 MV and 15 MV, at 90 cm source to skin distance, for four fields of 5 cm × 5 cm, 10 cm × 10 cm, 15 cm × 15 cm and 20 cm × 20 cm. Compared to the open field, the maximum dose with mask was closer to the surface of the phantom by about 1.4 mm and 1.2 mm for 6 MV and 15 MV X-Rays, respectively. The surface dose increase from 10% to 42% for 6 MV and from 5% to 28% for 15 MV X-Rays.

MR-guided breast radiotherapy: feasibility and magnetic-field impact on skin dose

NASA Astrophysics Data System (ADS)

van Heijst, Tristan C. F.; den Hartogh, Mariska D.; Lagendijk, Jan J. W.; Desirée van den Bongard, H. J. G.; van Asselen, Bram

2013-09-01

The UMC Utrecht MRI/linac (MRL) design provides image guidance with high soft-tissue contrast, directly during radiotherapy (RT). Breast cancer patients are a potential group to benefit from better guidance in the MRL. However, due to the electron return effect, the skin dose can be increased in presence of a magnetic field. Since large skin areas are generally involved in breast RT, the purpose of this study is to investigate the effects on the skin dose, for whole-breast irradiation (WBI) and accelerated partial-breast irradiation (APBI). In ten patients with early-stage breast cancer, targets and organs at risk (OARs) were delineated on postoperative CT scans co-registered with MRI. The OARs included the skin, comprising the first 5 mm of ipsilateral-breast tissue, plus extensions. Three intensity-modulated RT techniques were considered (2× WBI, 1× APBI). Individual beam geometries were used for all patients. Specially developed MRL treatment-planning software was used. Acceptable plans were generated for 0 T, 0.35 T and 1.5 T, using a class solution. The skin dose was augmented in WBI in the presence of a magnetic field, which is a potential drawback, whereas in APBI the induced effects were negligible. This opens possibilities for developing MR-guided partial-breast treatments in the MRL.

Can the Equivalent Sphere Model Approximate Organ Doses in Space Radiation Environments?

NASA Technical Reports Server (NTRS)

Zi-Wei, Lin

2007-01-01

In space radiation calculations it is often useful to calculate the dose or dose equivalent in blood-forming organs (BFO). the skin or the eye. It has been customary to use a 5cm equivalent sphere to approximate the BFO dose. However previous studies have shown that a 5cm sphere gives conservative dose values for BFO. In this study we use a deterministic radiation transport with the Computerized Anatomical Man model to investigate whether the equivalent sphere model can approximate organ doses in space radiation environments. We find that for galactic cosmic rays environments the equivalent sphere model with an organ-specific constant radius parameter works well for the BFO dose equivalent and marginally well for the BFO dose and the dose equivalent of the eye or the skin. For solar particle events the radius parameters for the organ dose equivalent increase with the shielding thickness, and the model works marginally for BFO but is unacceptable for the eye or the skin The ranges of the radius parameters are also shown and the BFO radius parameters are found to be significantly larger than 5 cm in all eases.

TH-AB-207A-03: Skin Dose to Patients Receiving Multiple CTA and CT Exams of the Head

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nawfel, RD; Young, G

Purpose: To measure patient skin dose from CT angiography (CTA) and CT exams of the head, and determine if patients having multiple exams could receive cumulative doses that approach or exceed deterministic thresholds. Methods: This study was HIPAA compliant and conducted with IRB approval. Patient skin doses were measured over a 4 month period using nanoDot OSL dosimeters placed on the head of 52 patients for two CT scanners. On each scanner, 26 patients received CT exams (scanner 1: 10 females, 16 males, mean age 64.2 years; scanner 2: 18 females, 8 males, mean age 61.2 years). CT exam dosemore » metrics, CTDIvol and dose-length product (DLP) were recorded for each exam. Additionally, skin dose was measured on an acrylic skull phantom in each scanner and on a neuro-interventional imaging system using clinical protocols. Measured dose data was used to estimate peak skin dose (PSD) for 4 patients receiving multiple exams including CTA, head CT, and cerebral angiography. Results: For scanner 1, the mean PSD for CTA exams (98.9 ± 5.3 mGy) and for routine head CT exams (39.2 ± 3.7 mGy) agreed reasonably well with the PSD measured on the phantom, 105.4 mGy and 40.0 mGy, respectively. Similarly for scanner 2, the mean PSD for CTA exams (98.8 ± 7.4 mGy) and for routine head CT exams (42.9 ± 9.4 mGy) compared well with phantom measurements, 95.2 mGy and 37.6 mGy, respectively. In addition, the mean PSD was comparable between scanners for corresponding patient exams, CTA and routine head CT respectively. PSD estimates ranged from 1.9 – 4.5 Gy among 4 patients receiving multiple exams. Conclusion: Patients having several exams including both CTA and routine head CT may receive cumulative doses approaching or exceeding the threshold for single dose deterministic effects.« less

SU-F-T-504: Non-Divergent Planning Method for Craniospinal Irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sperling, N; Bogue, J; Parsai, E

2016-06-15

Purpose: Traditional Craniospinal Irradiation (CSI) planning techniques require careful field placement to allow optimal divergence and field overlap at depth, and measurement of skin gap. The result of this is a necessary field overlap resulting in dose heterogeneity in the spinal canal. A novel, nondivergent field matching method has been developed to allow simple treatment planning and delivery without the need to measure skin gap. Methods: The CSI patient was simulated in the prone, and a plan was developed. Bilateral cranial fields were designed with couch and collimator rotation to eliminate divergence with the upper spine field and minimize anteriormore » divergence into the lenses. Spinal posterior-to-anterior fields were designed with the couch rotated to 90 degrees to allow gantry rotation to eliminate divergence at the match line, and the collimator rotated to 90 degrees to allow appropriate field blocking with the MLCs. A match line for the two spinal fields was placed and the gantry rotated to equal angles in opposite directions about the match line. Jaw positions were then defined to allow 1mm overlap at the match line to avoid cold spots. A traditional CSI plan was generated using diverging spinal fields, and a comparison between the two techniques was generated. Results: The non-divergent treatment plan was able to deliver a highly uniform dose to the spinal cord with a cold spot of only 95% and maximum point dose of 115.8%, as compared to traditional plan cold spots of 87% and hot spots of 132% of the prescription dose. Conclusion: A non-divergent method for planning CSI patients has been developed and clinically implemented. Planning requires some geometric manipulation in order to achieve an adequate dose distribution, however, it can help to manage cold spots and simplify the shifts needed between spinal fields.« less

SU-F-T-325: On the Use of Bolus in Dosimetry and Dose Reduction for Pacemaker and Defibrillator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, W; Kenneth, R; Higgins, S

Purpose: Special attention is required in planning and administering radiation therapy to patients with cardiac implantable electronic devices (CIEDs), such as pacemaker and defibrillator. The range of dose to CIEDs that can induce malfunction is very large among CIEDs. Significant defects have been reported at dose as low as 0.15Gy. Failures causing discomfort have been reported at dose as low as 0.05Gy. Therefore, accurate estimation of dose to CIED and dose reduction are both important even if the dose is expected to be less than the often-used 2Gy limit. We investigate the use of bolus in in vivo dosimetry formore » CIEDs. Methods: In our clinic, high-energy beams (>10MV) are not used for patients with CIED due to neutron production. Solid water phantom measurements of out-of-field dose for a 6MV beam were performed using parallel plate chamber at different depth with and without 2cm bolus covering the chamber. In vivo dosimetry at skin surface above the pacemaker was performed with and without bolus for 3 patients with pacemaker <5cm from the field edge. Results: Chamber measured dose at depth ∼1 to 1.5cm below the skin surface, where the CIED is normally located, was reduced by ∼6% – 20% with bolus. The dose reduction became smaller at deeper depth. In vivo dosimetry at skin surface also yielded ∼20% – 60% lower dose when using bolus for the 3 patients. In general, TPS calculation underestimated the dose. The dose measured with bolus is closer to the dose at the depth of the pacemaker and less affected by contaminant electrons and linac head leakage. Conclusion: In vivo CIED dose measurements should be performed with 1 to 2cm bolus covering the dosimeter on the skin above the CIED for more accurate CIED dose estimation. The use of bolus also reduces the dose delivered to CIED.« less

Minimal and maximal incidence rates of skin cancer in Caucasians estimated by use of sigmoidal UV dose-incidence curves.

PubMed

Juzeniene, Asta; Grigalavicius, Mantas; Baturaite, Zivile; Moan, Johan

2014-11-01

Sigmoidal (S-shaped) dose-cancer incidence relationships are often observed in animal bioassays for carcinogenicity. Ultraviolet (UV) radiation is an established skin carcinogen. The aim of this study is to examine if S-shaped curves describe the relationship between solar UV doses and skin cancer incidences, and if such relationships can be used to estimate threshold levels of non-carcinogenic UV exposure, as well as maximal incidence rates. We studied the incidence rate-annual erythema-effective UV dose relationship for squamous cell carcinoma (SCC), basal cell carcinoma (BCC) and cutaneous melanoma (CM) among different Caucasian populations in Europe, Australia and New Zealand. Our analysis indicates that S-shaped associations describe the data well (P < 0.0001). The age-adjusted incidence rates for cases expected to be due to other causes than solar UV exposure (at zero UV dose) were found to be around 0.6, 9.7 and 4.0 per 100,000 for women in 1997-2007 for SCC, BCC and CM, respectively, and around 1.2, 14.3 and 2.6 per 100,000 for men. The analysis indicates that SCC, BCC and CM have maximal incidence of 361 ± 24, 1544 ± 49 and 36 ± 4 per 100,000 for women, and 592 ± 35, 2204 ± 109 and 50 ± 4 per 100,000 for men. Between 89 and 95% of the annual CM cases, around 99.8% SCC and 99.4% BCC cases are caused by solar UV exposure. The analysis did not identify any "safe" UV dose below which the risk for skin cancer was absent. Avoidance of UV radiation has a potential to reduce the incidence of skin cancer in fair-skinned population. Copyright © 2014 Elsevier GmbH. All rights reserved.

The Bebig Valencia-type skin applicators: Dosimetric study and implementation of a dosimetric hybrid technique.

PubMed

Anagnostopoulos, Georgios; Andrássy, Michael; Baltas, Dimos

To determine the relative dose rate distribution in water for the Bebig 20 mm and 30 mm skin applicators and report results in a form suitable for potential clinical use. Results for both skin applicators are also provided in the form of a hybrid Task Group 43 (TG-43) dosimetry technique. Furthermore, the radiation leakage around both skin applicators from the radiation protection point of view and the impact of the geometrical source position uncertainties are studied and reported. Monte Carlo simulations were performed using the MCNP 6.1 general purpose code, which was benchmarked against published dosimetry data for the Bebig Ir2.A85-2 high-dose-rate iridium-192 source, as well as the dosimetry data for the two Elekta skin applicators. Both Bebig skin applicators were modeled, and the dose rate distributions in a water phantom were calculated. The dosimetric quantities derived according to a hybrid TG-43 dosimetry technique are provided with their corresponding uncertainty values. The air kerma rate in air was simulated in the vicinity of each skin applicator to assess the radiation leakage. Results from the Monte Carlo simulations of both skin applicators are presented in the form of figures and relative dose rate tables, and additionally with the aid of the quantities defined in the hybrid TG-43 dosimetry technique and their corresponding uncertainty values. Their output factors, flatness, and penumbra values were found comparable to the Elekta skin applicators. The radiation shielding was evaluated to be adequate. The effect of potential uncertainties in source positioning on dosimetry should be investigated as part of applicator commissioning. Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Dermal damage promoted by repeated low-level UV-A1 exposure despite tanning response in human skin.

PubMed

Wang, Frank; Smith, Noah R; Tran, Bao Anh Patrick; Kang, Sewon; Voorhees, John J; Fisher, Gary J

2014-04-01

Solar UV irradiation causes photoaging, characterized by fragmentation and reduced production of type I collagen fibrils that provide strength to skin. Exposure to UV-B irradiation (280-320 nm) causes these changes by inducing matrix metalloproteinase 1 and suppressing type I collagen synthesis. The role of UV-A irradiation (320-400 nm) in promoting similar molecular alterations is less clear yet important to consider because it is 10 to 100 times more abundant in natural sunlight than UV-B irradiation and penetrates deeper into the dermis than UV-B irradiation. Most (approximately 75%) of solar UV-A irradiation is composed of UV-A1 irradiation (340-400 nm), which is also the primary component of tanning beds. To evaluate the effects of low levels of UV-A1 irradiation, as might be encountered in daily life, on expression of matrix metalloproteinase 1 and type I procollagen (the precursor of type I collagen). In vivo biochemical analyses were conducted after UV-A1 irradiation of normal human skin at an academic referral center. Participants included 22 healthy individuals without skin disease. Skin pigmentation was measured by a color meter (chromometer) under the L* variable (luminescence), which ranges from 0 (black) to 100 (white). Gene expression in skin samples was assessed by real-time polymerase chain reaction. Lightly pigmented human skin (L* >65) was exposed up to 4 times (1 exposure/d) to UV-A1 irradiation at a low dose (20 J/cm2), mimicking UV-A levels from strong sun exposure lasting approximately 2 hours. A single exposure to low-dose UV-A1 irradiation darkened skin slightly and did not alter matrix metalloproteinase 1 or type I procollagen gene expression. With repeated low-dose UV-A1 irradiation, skin darkened incrementally with each exposure. Despite this darkening, 2 or more exposures to low-dose UV-A1 irradiation significantly induced matrix metalloproteinase 1 gene expression, which increased progressively with successive exposures. Repeated UV-A1 exposures did not suppress type I procollagen expression. A limited number of low-dose UV-A1 exposures, as commonly experienced in daily life, potentially promotes photoaging by affecting breakdown, rather than synthesis, of collagen. Progressive skin darkening in response to repeated low-dose UV-A1 exposures in lightly pigmented individuals does not prevent UV-A1-induced collagenolytic changes. Therefore, for optimal protection against skin damage, sunscreen formulations should filter all UV wavelengths, including UV-A1 irradiation.

Acceleration of skin wound healing by low-dose indirect ionizing radiation in male rats.

PubMed

Jabbari, Nasrollah; Farjah, Gholam Hossein; Ghadimi, Behnam; Zanjani, Hajar; Heshmatian, Behnam

2017-08-01

A recent hypothesis has revealed that low-dose irradiation (LDI) with ionizing radiation might have a promoting effect on fracture healing. The aim of this study was to investigate the influence of direct (electron beam) and indirect (gamma-ray) low-dose ionizing irradiations on the wound healing process in male rats. In 72 male rats, a full-thickness wound was incised. The animals were randomly assigned to three groups, each with 24 rats. The first two groups were named IG-I and IG-II and respectively exposed to electron and gamma-radiations (75 cGy) immediately after the surgical procedure. The third group was considered as the control (CG) and remained untreated. Skin biopsies from the subgroups were collected on days 3, 7, 15, and 21 after the operation and evaluated using histological and biomechanical methods. Data were analyzed by one-way ANOVA, followed by Tukey's post hoc test using SPSS 20 software. Histological studies of tissues showed that the mean number of fibroblasts, macrophages, blood vessel sections, and neutrophils on the third and seventh days after the surgery in the gamma-treated group was higher than that in both other groups. In contrast, on day 21, the mean number of mentioned cells in the gamma-treated group was lower than in the other two groups. In addition, the mean maximum stress value was significantly greater in the gamma-treated group. Results of this study showed that gamma-ray irradiation is effective in the acceleration of wound healing. Copyright © 2017. Published by Elsevier Taiwan.

Can the Equivalent Sphere Model Approximate Organ Doses in Space?

NASA Technical Reports Server (NTRS)

Lin, Zi-Wei

2007-01-01

For space radiation protection it is often useful to calculate dose or dose,equivalent in blood forming organs (BFO). It has been customary to use a 5cm equivalent sphere to. simulate the BFO dose. However, many previous studies have concluded that a 5cm sphere gives very different dose values from the exact BFO values. One study [1] . concludes that a 9 cm sphere is a reasonable approximation for BFO'doses in solar particle event environments. In this study we use a deterministic radiation transport [2] to investigate the reason behind these observations and to extend earlier studies. We take different space radiation environments, including seven galactic cosmic ray environments and six large solar particle events, and calculate the dose and dose equivalent in the skin, eyes and BFO using their thickness distribution functions from the CAM (Computerized Anatomical Man) model [3] The organ doses have been evaluated with a water or aluminum shielding of an areal density from 0 to 20 g/sq cm. We then compare with results from the equivalent sphere model and determine in which cases and at what radius parameters the equivalent sphere model is a reasonable approximation. Furthermore, we address why the equivalent sphere model is not a good approximation in some cases. For solar particle events, we find that the radius parameters for the organ dose equivalent increase significantly with the shielding thickness, and the model works marginally for BFO but is unacceptable for the eye or the skin. For galactic cosmic rays environments, the equivalent sphere model with an organ-specific constant radius parameter works well for the BFO dose equivalent, marginally well for the BFO dose and the dose equivalent of the eye or the skin, but is unacceptable for the dose of the eye or the skin. The ranges of the radius parameters are also being investigated, and the BFO radius parameters are found to be significantly, larger than 5 cm in all cases, consistent with the conclusion of an earlier study [I]. The radius parameters for the dose equivalent in GCR environments are approximately between 10 and I I cm for the BFO, 3.7 to 4.8 cm for the eye, and 3.5 to 5.6 cm for the skin; while the radius parameters are between 10 and 13 cm for the BFO dose.

SU-E-T-206: Comparison of EBT and EBT3 RadioChromic Films in Radiation Field of Parotid Cancer Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toosi, T Bahreyni; Mianaei, F Khorshidi; Ghorbani, M

Purpose: The aim of the current study is to compare EBT and EBT3 RadioChromic films in dosimetry of radiotherapy fields for treatment of parotid cancer. Methods: The calibrations of EBT and EBT3 films were performed with the same setups for doses ranging from 0.2 Gy to 5 Gy using 6 MV photon beam of a Siemens Primus linac. These films were scanned in color mode (RGB) by a Microtek (1000XL) scanner and the red color channel data was extracted. Treatment planning for parotid cancer radiation therapy was performed on a RANDO phantom. Skin dose was measured at different points inmore » the right anterior oblique (RAO) and right posterior oblique (RPO) fields by EBT and EBT3 films. Results: Dosimetry was performed with the same conditions for the two film types for calibration and in-phantom in parotid cancer radiotherapy. The measured net optical density (NOD) in EBT film was in some extent higher than that from EBT3 film. The minimum difference between these two films under calibration conditions was about 2.9% (for 0.2 Gy). However, the maximum difference was 35.5% (for 0.5 Gy). In the therapeutic fields of parotid cancer radiotherapy at different points, the measured dose from EBT film was higher than the EBT3 film. In these fields the minimum and maximum measured dose differences were 16.0% and 25.5%, respectively. Conclusion: With the same irradiation and reading conditions, EBT film demonstrates higher NOD than the EBT3 film. This effect may be related to the higher sensitivity of EBT film over EBT3 film. However, the obtained dose differences between these two films in low dose range can be due to the differences in fitting functions applied following the calibration process.« less

[SUBSTANTIATION OF DOSE LIMITS FOR A NEW NORMATIVE DOCUMENT ON RADIATION SAFETY OF LONG-DURATION SPACE MISSIONS AT ORBIT ALTITUDES OF UP TO 500 KM].

PubMed

Ushakov, I B; Grigoriev, Yu G; Shafirkin, A V; Shurshakov, V A

2016-01-01

Review of the data of experimental radiobiology and epidemiological follow-up of large groups of people subjected to radiation exposures on Earth has been undertaken to substantiate dose limits for critical organs of cosmonauts in order to ensure good performance and vitality while on long-duration orbital missions. The career dose limits for cosmonauts and astronauts established earlier in the USSR and USA amounted to nothing more but banning the risk of cancer death increase to 3%. To apply more rigorous criteria of delayed radiation risks, the Russian limits for cosmonauts were revised to substantiate a 4-fold reduction of the average tissue equivalent dose maximum to 1 Sv. The total of cancer and non-cancer radiation risks over lifetime and probable reduction of mean life expectancy (MLE) were calculated using the model of radiation-induced mortality for mammals and taken as the main damage to health. The established dose limit is equal to the career dose for nuclear industry personnel set forth by Russian standard document NRB 99/2009. For better agreement of admissible threshold doses to critical human organs (bone marrow, lens and skin) in the revised radiation limits for long-duration space missions and radiation safety limits on Earth, reduction of dose limits for the critical organs were substantiated additionally; these limits comply with those for planned over-exposure on Earth in document NRB 99/2009.

Cherenkov imaging method for rapid optimization of clinical treatment geometry in total skin electron beam therapy

PubMed Central

Zhang, Rongxiao; Gladstone, David J.; Williams, Benjamin B.; Glaser, Adam K.; Pogue, Brian W.; Jarvis, Lesley A.

2016-01-01

Purpose: A method was developed utilizing Cherenkov imaging for rapid and thorough determination of the two gantry angles that produce the most uniform treatment plane during dual-field total skin electron beam therapy (TSET). Methods: Cherenkov imaging was implemented to gather 2D measurements of relative surface dose from 6 MeV electron beams on a white polyethylene sheet. An intensified charge-coupled device camera time-gated to the Linac was used for Cherenkov emission imaging at sixty-two different gantry angles (1° increments, from 239.5° to 300.5°). Following a modified Stanford TSET technique, which uses two fields per patient position for full body coverage, composite images were created as the sum of two beam images on the sheet; each angle pair was evaluated for minimum variation across the patient region of interest. Cherenkov versus dose correlation was verified with ionization chamber measurements. The process was repeated at source to surface distance (SSD) = 441, 370.5, and 300 cm to determine optimal angle spread for varying room geometries. In addition, three patients receiving TSET using a modified Stanford six-dual field technique with 6 MeV electron beams at SSD = 441 cm were imaged during treatment. Results: As in previous studies, Cherenkov intensity was shown to directly correlate with dose for homogenous flat phantoms (R2 = 0.93), making Cherenkov imaging an appropriate candidate to assess and optimize TSET setup geometry. This method provided dense 2D images allowing 1891 possible treatment geometries to be comprehensively analyzed from one data set of 62 single images. Gantry angles historically used for TSET at their institution were 255.5° and 284.5° at SSD = 441 cm; however, the angles optimized for maximum homogeneity were found to be 252.5° and 287.5° (+6° increase in angle spread). Ionization chamber measurements confirmed improvement in dose homogeneity across the treatment field from a range of 24.4% at the initial angles, to only 9.8% with the angles optimized. A linear relationship between angle spread and SSD was observed, ranging from 35° at 441 cm, to 39° at 300 cm, with no significant variation in percent-depth dose at midline (R2 = 0.998). For patient studies, factors influencing in vivo correlation between Cherenkov intensity and measured surface dose are still being investigated. Conclusions: Cherenkov intensity correlates to relative dose measured at depth of maximum dose in a uniform, flat phantom. Imaging of phantoms can thus be used to analyze and optimize TSET treatment geometry more extensively and rapidly than thermoluminescent dosimeters or ionization chambers. This work suggests that there could be an expanded role for Cherenkov imaging as a tool to efficiently improve treatment protocols and as a potential verification tool for routine monitoring of unique patient treatments. PMID:26843259

Cherenkov imaging method for rapid optimization of clinical treatment geometry in total skin electron beam therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andreozzi, Jacqueline M., E-mail: Jacqueline.M.Andreozzi.th@dartmouth.edu, E-mail: Lesley.A.Jarvis@hitchcock.org; Glaser, Adam K.; Zhang, Rongxiao

2016-02-15

Purpose: A method was developed utilizing Cherenkov imaging for rapid and thorough determination of the two gantry angles that produce the most uniform treatment plane during dual-field total skin electron beam therapy (TSET). Methods: Cherenkov imaging was implemented to gather 2D measurements of relative surface dose from 6 MeV electron beams on a white polyethylene sheet. An intensified charge-coupled device camera time-gated to the Linac was used for Cherenkov emission imaging at sixty-two different gantry angles (1° increments, from 239.5° to 300.5°). Following a modified Stanford TSET technique, which uses two fields per patient position for full body coverage, compositemore » images were created as the sum of two beam images on the sheet; each angle pair was evaluated for minimum variation across the patient region of interest. Cherenkov versus dose correlation was verified with ionization chamber measurements. The process was repeated at source to surface distance (SSD) = 441, 370.5, and 300 cm to determine optimal angle spread for varying room geometries. In addition, three patients receiving TSET using a modified Stanford six-dual field technique with 6 MeV electron beams at SSD = 441 cm were imaged during treatment. Results: As in previous studies, Cherenkov intensity was shown to directly correlate with dose for homogenous flat phantoms (R{sup 2} = 0.93), making Cherenkov imaging an appropriate candidate to assess and optimize TSET setup geometry. This method provided dense 2D images allowing 1891 possible treatment geometries to be comprehensively analyzed from one data set of 62 single images. Gantry angles historically used for TSET at their institution were 255.5° and 284.5° at SSD = 441 cm; however, the angles optimized for maximum homogeneity were found to be 252.5° and 287.5° (+6° increase in angle spread). Ionization chamber measurements confirmed improvement in dose homogeneity across the treatment field from a range of 24.4% at the initial angles, to only 9.8% with the angles optimized. A linear relationship between angle spread and SSD was observed, ranging from 35° at 441 cm, to 39° at 300 cm, with no significant variation in percent-depth dose at midline (R{sup 2} = 0.998). For patient studies, factors influencing in vivo correlation between Cherenkov intensity and measured surface dose are still being investigated. Conclusions: Cherenkov intensity correlates to relative dose measured at depth of maximum dose in a uniform, flat phantom. Imaging of phantoms can thus be used to analyze and optimize TSET treatment geometry more extensively and rapidly than thermoluminescent dosimeters or ionization chambers. This work suggests that there could be an expanded role for Cherenkov imaging as a tool to efficiently improve treatment protocols and as a potential verification tool for routine monitoring of unique patient treatments.« less

Red emission phosphor for real-time skin dosimeter for fluoroscopy and interventional radiology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakamura, Masaaki, E-mail: QYJ05476@nifty.com; Chida, Koichi; Zuguchi, Masayuki

2014-10-15

Purpose: There are no effective real-time direct skin dosimeters for interventional radiology. Such a scintillation dosimeter would be available if there was a suitable red emission phosphor in the medical x-ray range, since the silicon photodiode is a highly efficient device for red light. However, it is unknown whether there is a suitable red emission phosphor. The purpose of this study is to find a suitable red emission phosphor that can be used in x-ray dosimeters. Methods: Five kinds of phosphors which emit red light when irradiated with electron beams or ultraviolet rays in practical devices were chosen. For themore » brightness measurement, phosphor was put into transparent plastic cells or coated onto plastic sheets. The phosphors were irradiated with medical range x-rays [60–120 kV(peak), maximum dose rate of 160 mGy min{sup −1}], and the emission was measured by a luminance meter. Several characteristics, such as brightness, dose rate dependence, tube voltage dependence, and brightness stability, were investigated. Results: The luminescence of Y V O{sub 4}:Eu, (Y,Gd,Eu) BO{sub 3}, and Y{sub 2}O{sub 3}:Eu significantly deteriorated by 5%–10% when irradiated with continuous 2 Gy x-rays. The 0.5MgF{sub 2}⋅3.5MgO⋅GeO{sub 2}:Mn phosphor did not emit enough. Only the Y{sub 2}O{sub 2}S:Eu,Sm phosphor had hardly any brightness deterioration, and it had a linear relationship so that the x-ray dose rate could be determined from the brightness with sufficient accuracy. For the tube voltage dependence of the Y{sub 2}O{sub 2}S:Eu,Sm phosphor, the brightness per unit dose rate with 120 kV(peak) x-rays was 30% higher than that with 60 kV(peak) x-rays. Conclusions: Five kinds of phosphors were chosen as an x-ray scintillator for a real-time direct skin dosimeter. The Y V O{sub 4}:Eu, (Y,Gd,Eu)BO{sub 3}, and Y{sub 2}O{sub 3}:Eu phosphors had brightness deterioration caused by the x-rays. Only the Y{sub 2}O{sub 2}S:Eu,Sm phosphor had hardly any brightness deterioration, and it is a candidate for an x-ray scintillator for such a skin dosimeter.« less

SU-E-T-541: Bolus Effect of Thermoplastic Masks in IMRT and VMAT Head and Neck Treatments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhen, H; Nedzi, L; Chen, S

2014-06-01

Purpose: To quantitatively evaluate the bolus effect of thermoplalstic mask on patient skin dose during multi-field IMRT and VMAT treatment. Methods: The clinically approved target contours for five head and neck patients were deformably registered to an anthropomorphic Rando phantom. Two plans: Multifield IMRT plan with 7-9 beams and VMAT plan with 2-4 arcs were created for each patient following same dose constraints. 3mm skin was excluded from PTVs but not constrained during optimization. The prescription dose was 200-220 cGy/fraction. A thermoplastic head and shoulder mask was customized for the Rando phantom. Each plan was delivered to the phantom twicemore » with and without mask. During each delivery, two rectangular strips of EBT3 films (1cm x 6.8cm) were placed across the anterior upper and lower neck near PTVs to measure the surface dose. For consistency films were positioned at same locations for same patient. A total of 8 film strips were obtained for each patient. Film dose was calibrated in the range of 0-400cGy on the day of plan delivery. For dose comparison 3 regions of interests (ROIs) of 1×1 cm{sup 2} were selected at left, right and middle part of each film, resulting in 6 point doses at each plan delivery. Results: The films without mask show relatively uniform dose distribution while those with mask clearly show mesh pattern of mask, usually indicating an increase in skin dose. On average the increase in skin dose over all ROIs with mask was 31.9%(±14.8%) with a range of 11.4%- 58.4%. There is no statistically significant difference (p=0.44) between skin dose increase in VMAT (30.8%±15.3%) and IMRT delivery (33.0%±14.9%). Conclusion: Thermoplastic immobilization masks increase surface dose for HN patient by around 30%. The magnitude is comparable between multi-field IMRT and VMAT. Radiochromic EBT3 film serves as an effective tool to quantify bolus effect.« less

Ultrasound assisted chrome tanning: Towards a clean leather production technology.

PubMed

Mengistie, Embialle; Smets, Ilse; Van Gerven, Tom

2016-09-01

Nowadays, there is a growing demand for a cleaner, but still effective alternative for production processes like in the leather industry. Ultrasound (US) assisted processing of leather might be promising in this sense. In the present paper, the use of US in the conventional chrome tanning process has been studied at different pH, temperature, tanning time, chrome dose and US exposure time by exposing the skin before tanning and during tanning operation. Both prior exposure of the skin to US and US during tanning improves the chrome uptake and reduces the shrinkage significantly. Prior exposure of the skin to US increase the chrome uptake by 13.8% or reduces the chrome dose from 8% to 5% (% based on skin weight) and shorten the process time by half while US during tanning increases the chrome uptake by 28.5% or reduces the chrome dose from 8% to 4% (half) and the tanning time to one third compared to the control without US. Concomitantly, the resulting leather quality (measured as skin shrinkage) improved from 5.2% to 3.2% shrinkage in the skin exposed to US prior tanning and to 1.3% in the skin exposed to US during the tanning experiment. This study confirms that US chrome tanning is an effective and eco-friendly tanning process which can produce a better quality leather product in a shorter process time with a lower chromium dose. Copyright © 2016 Elsevier B.V. All rights reserved.

Wearable glass beads for in vivo dosimetry of total skin electron irradiation treatments

NASA Astrophysics Data System (ADS)

Nabankema, S. K.; Jafari, S. M.; Peet, S. C.; Binny, D.; Sylvander, S. R.; Crowe, S. B.

2017-11-01

Glass beads have recently been proposed for use as radiation therapy dosimeters. Glass beads have a number of characteristics that make them suitable for in vivo skin dose measurements, including an ability to be worn on a string, and therefore avoid possible patient discomfort that may result from the use of adhesives. In this study, their use for in vivo dose measurements in total skin electron irradiation treatments has been tested. First, the dosimetric properties of cylindrical beads with a 3 mm diameter were characterised using electron fields produced by a linear accelerator. The mean individual bead reproducibility was demonstrated to be within 3%; and a batch variation of 7% was observed. The beads were shown to have a linear dose response, and both dose rate and beam energy independence, within the measurement uncertainty. Phantom measurements were then performed for a total skin electron irradiation beam arrangement, and results compared against optically stimulated luminescent dosimeters at five anatomical sites. For a majority of measurement locations, agreement within 3% was observed between the two dosimetry techniques, demonstrating the feasibility of glass beads as in vivo dosimeters for total skin electron irradiation; though further investigation may be needed to minimise uncertainty in results.

Space radiation dose analysis for solar flare of August 1989

NASA Technical Reports Server (NTRS)

Nealy, John E.; Simonsen, Lisa C.; Sauer, Herbert H.; Wilson, John W.; Townsend, Lawrence W.

1990-01-01

Potential dose and dose rate levels to astronauts in deep space are predicted for the solar flare event which occurred during the week of August 13, 1989. The Geostationary Operational Environmental Satellite (GOES-7) monitored the temporal development and energy characteristics of the protons emitted during this event. From these data, differential fluence as a function of energy was obtained in order to analyze the flare using the Langley baryon transport code, BRYNTRN, which describes the interactions of incident protons in matter. Dose equivalent estimates for the skin, ocular lens, and vital organs for 0.5 to 20 g/sq cm of aluminum shielding were predicted. For relatively light shielding (less than 2 g/sq cm), the skin and ocular lens 30-day exposure limits are exceeded within several hours of flare onset. The vital organ (5 cm depth) dose equivalent is exceeded only for the thinnest shield (0.5 g/sq cm). Dose rates (rem/hr) for the skin, ocular lens, and vital organs are also computed.

Space radiation dose analysis for solar flare of August 1989

NASA Astrophysics Data System (ADS)

Nealy, John E.; Simonsen, Lisa C.; Sauer, Herbert H.; Wilson, John W.; Townsend, Lawrence W.

1990-12-01

Potential dose and dose rate levels to astronauts in deep space are predicted for the solar flare event which occurred during the week of August 13, 1989. The Geostationary Operational Environmental Satellite (GOES-7) monitored the temporal development and energy characteristics of the protons emitted during this event. From these data, differential fluence as a function of energy was obtained in order to analyze the flare using the Langley baryon transport code, BRYNTRN, which describes the interactions of incident protons in matter. Dose equivalent estimates for the skin, ocular lens, and vital organs for 0.5 to 20 g/sq cm of aluminum shielding were predicted. For relatively light shielding (less than 2 g/sq cm), the skin and ocular lens 30-day exposure limits are exceeded within several hours of flare onset. The vital organ (5 cm depth) dose equivalent is exceeded only for the thinnest shield (0.5 g/sq cm). Dose rates (rem/hr) for the skin, ocular lens, and vital organs are also computed.

Duration of skin photosensitivity and incidence of photosensitivity reactions after administration of verteporfin.

PubMed

Houle, Jean-Marie; Strong, H Andrew

2002-12-01

Verteporfin (Visudyne, Novartis AG) is a light-activated drug that reduces the risk of vision loss in patients with certain types of choroidal neovascularization (CNV). Because photosensitivity can occur with photosensitizers, it is important for ophthalmologists providing verteporfin therapy to understand its time course and duration, as well as the incidence of photosensitivity reactions. Data were obtained from three sources: 1) the time course of skin photosensitivity in 17 volunteers by measuring erythema/edema over time after verteporfin, using red light exposure; 2) the duration of skin photosensitivity in 30 patients with skin cancer by exposing skin to simulated solar light and calculating the daily minimal erythematous dose; and 3) the incidences of photosensitivity reactions as recorded in three phase III trials in patients with CNV secondary to age-related macular degeneration or pathologic myopia who received the regimen of verteporfin therapy currently approved by regulatory authorities (infusion of 6 mg/m(2) body surface area). 1) Skin photosensitivity was high at the first timepoint of 1.5 hours after dosing and decreased rapidly thereafter; 2) the duration of skin photosensitivity was dose dependent, ranging from 2.0 to 6.7 days at 6 to 20 mg/m(2), respectively (mean of 2 days at a dose of 6 mg/m(2)); and 3) photosensitivity reactions occurred in only 2.2% of patients in the phase III trials, including two severe events, one secondary to extravasation. All treatment-related reactions in the phase III trials occurred within the first 2 days after dosing, with the exception of two mild reactions and one moderate reaction that occurred 3 days after treatment. Verteporfin is associated with short-lived photosensitivity and a low incidence of photosensitivity reactions in clinical trials, most of which could probably have been avoided by adherence to protocol instructions for skin protection.

Attenuated noradrenergic sensitivity during local cooling in aged human skin

PubMed Central

Thompson, Caitlin S; Holowatz, Lacy A; Kenney, W. Larry

2005-01-01

Reflex-mediated cutaneous vasoconstriction (VC) is impaired in older humans; however, it is unclear whether this blunted VC also occurs during local cooling, which mediates VC through different mechanisms. We tested the hypothesis that the sensitization of cutaneous vessels to noradrenaline (NA) during direct skin cooling seen in young skin is blunted in aged skin. In 11 young (18–30 years) and 11 older (62–76 years) men and women, skin blood flow was monitored at two forearm sites with laser Doppler (LD) flowmetry while local skin temperature was cooled and clamped at 24°C. Cutaneous vascular conductance (CVC; LD flux/mean arterial pressure) was expressed as percentage change from baseline (%ΔCVCbase). At one site, five doses of NA (10−10–10−2m) were sequentially infused via intradermal microdialysis during cooling while the other 24°C site served as control (Ringer solution + cooling). At control sites, VC due to cooling alone was similar in young versus older (−54 ± 5 versus −56 ± 3%ΔCVCbase, P= 0.46). In young, NA infusions induced additional dose-dependent VC (10−8, 10−6, 10−4 and 10−2m: −70 ± 2, −72 ± 3, −78 ± 3 and −79 ± 4%ΔCVCbase; P < 0.05 versus control). In older subjects, further VC did not occur until the highest infused dose of NA (10−2m: −70 ± 5%ΔCVCbase; P < 0.05 versus control). When cutaneous arterioles are sensitized to NA by direct cooling, young skin exhibits the capacity to further constrict to NA in a dose-dependent manner. However, older skin does not display enhanced VC capacity until treated with saturating doses of NA, possibly due to age-associated decrements in Ca2+ availability or α2C-adrenoceptor function. PMID:15705648

High-dose methylprednisolone pulse therapy for treatment of refractory intestinal involvement caused by Henoch-Schönlein purpura: a case report.

PubMed

Kang, Hyun Sik; Chung, Hee Sup; Kang, Ki-Soo; Han, Kyoung Hee

2015-03-24

Henoch-Schönlein purpura is an immunoglobulin A-mediated, small vascular inflammatory disease that can be associated with palpable purpura, arthralgia, abdominal pain, or nephritis. The presence of purpura facilitates the diagnosis of Henoch-Schönlein purpura at the onset of associated symptoms, whereas the absence of purpura makes the diagnosis challenging. It is important to diagnose Henoch-Schönlein purpura with delayed-onset skin purpura to avoid unnecessary surgery for acute abdomen. Most cases of Henoch-Schönlein purpura with severe abdominal pain are treated with low-dose steroids and intravenous immunoglobulin. A 15-year-old Korean girl complained of severe abdominal pain and delayed-onset purpura on admission. Henoch-Schönlein purpura was diagnosed based on endoscopic findings of hemorrhagic duodenitis and duodenal vasculitis and abdominal computed tomography findings of edematous bowels. Two common initial treatments, a low-dose steroid and intravenous immunoglobulin, were administered, but there was no improvement for 1 month. Subsequently, we used high-dose intravenous methylprednisolone pulse therapy (30 mg/kg/day, with a maximum of 1g/day), which dramatically alleviated her abdominal symptoms. High-dose intravenous methylprednisolone pulse therapy can be used as the ultimate treatment for delayed-onset Henoch-Schönlein purpura with severe abdominal pain when symptoms do not improve after low-dose steroid and intravenous immunoglobulin treatments.

On the Use of Optically Stimulated Luminescent Dosimeter for Surface Dose Measurement during Radiotherapy

PubMed Central

Yusof, Fasihah Hanum; Ung, Ngie Min; Wong, Jeannie Hsiu Ding; Jong, Wei Loong; Ath, Vannyat; Phua, Vincent Chee Ee; Heng, Siew Ping; Ng, Kwan Hoong

2015-01-01

This study was carried out to investigate the suitability of using the optically stimulated luminescence dosimeter (OSLD) in measuring surface dose during radiotherapy. The water equivalent depth (WED) of the OSLD was first determined by comparing the surface dose measured using the OSLD with the percentage depth dose at the buildup region measured using a Markus ionization chamber. Surface doses were measured on a solid water phantom using the OSLD and compared against the Markus ionization chamber and Gafchromic EBT3 film measurements. The effect of incident beam angles on surface dose was also studied. The OSLD was subsequently used to measure surface dose during tangential breast radiotherapy treatments in a phantom study and in the clinical measurement of 10 patients. Surface dose to the treated breast or chest wall, and on the contralateral breast were measured. The WED of the OSLD was found to be at 0.4 mm. For surface dose measurement on a solid water phantom, the Markus ionization chamber measured 15.95% for 6 MV photon beam and 12.64% for 10 MV photon beam followed by EBT3 film (23.79% and 17.14%) and OSLD (37.77% and 25.38%). Surface dose increased with the increase of the incident beam angle. For phantom and patient breast surface dose measurement, the response of the OSLD was higher than EBT3 film. The in-vivo measurements were also compared with the treatment planning system predicted dose. The OSLD measured higher dose values compared to dose at the surface (Hp(0.0)) by a factor of 2.37 for 6 MV and 2.01 for 10 MV photon beams, respectively. The measurement of absorbed dose at the skin depth of 0.4 mm by the OSLD can still be a useful tool to assess radiation effects on the skin dermis layer. This knowledge can be used to prevent and manage potential acute skin reaction and late skin toxicity from radiotherapy treatments. PMID:26052690

Inter-Individual Variability in Human Response to Low-Dose Ionizing Radiation, Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rocke, David

2016-08-01

In order to investigate inter-individual variability in response to low-dose ionizing radiation, we are working with three models, 1) in-vivo irradiated human skin, for which we have a realistic model, but with few subjects, all from a previous project, 2) ex-vivo irradiated human skin, for which we also have a realistic model, though with the limitations involved in keeping skin pieces alive in media, and 3) MatTek EpiDermFT skin plugs, which provides a more realistic model than cell lines, which is more controllable than human samples.

The safety of the H1N1 influenza A vaccine in egg allergic individuals.

PubMed

Greenhawt, Matthew J; Chernin, Anna S; Howe, Laura; Li, James T; Sanders, Georgiana

2010-11-01

The safety of H1N1 vaccine is unknown in egg allergic (EA) recipients. To establish the safety of administering H1N1 vaccine and to evaluate the predictability of H1N1 skin testing in EA patients. In a controlled, prospective trial, H1N1 skin testing and vaccination was compared between EA patients (n = 105) and non-EA controls (n = 19). Those with negative H1N1 skin test results received a full H1N1 dose; those with a positive skin test result received a graded challenge (10%, 90%). Booster vaccine, if required, was given as a single dose from a different lot without prior testing. Prick and intradermal test results were positive in 3 (2.4%) of 124 and 41 (33.1%) of 124 study participants, respectively. Forty-one individuals received a 2-step graded vaccine challenge, including 13 of 25 with a history of egg anaphylaxis. No significant allergic reactions resulted from either method of vaccination or from subsequent booster doses. All study participants received the H1N1 vaccine without significant allergic reactions. Skin testing is unnecessary and does not predict vaccine tolerance. All study participants who received a graded challenge tolerated a single dose booster from a different, untested lot, including 7 individuals with a history of egg-induced anaphylaxis. We recommend administration of H1N1 vaccine to EA children without prior skin testing or graded challenge dosing. Copyright © 2010 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Low-dose (10-Gy) total skin electron beam therapy for cutaneous T-cell lymphoma: an open clinical study and pooled data analysis.

PubMed

Kamstrup, Maria R; Gniadecki, Robert; Iversen, Lars; Skov, Lone; Petersen, Peter Meidahl; Loft, Annika; Specht, Lena

2015-05-01

Cutaneous T-cell lymphomas (CTCLs) are dominated by mycosis fungoides (MF) and Sézary syndrome (SS), and durable disease control is a therapeutic challenge. Standard total skin electron beam therapy (TSEBT) is an effective skin-directed therapy, but the possibility of retreatments is limited to 2 to 3 courses in a lifetime due to skin toxicity. This study aimed to determine the clinical effect of low-dose TSEBT in patients with MF and SS. In an open clinical study, 21 patients with MF/SS stages IB to IV were treated with low-dose TSEBT over <2.5 weeks, receiving a total dose of 10 Gy in 10 fractions. Data from 10 of these patients were published previously but were included in the current pooled data analysis. Outcome measures were response rate, duration of response, and toxicity. The overall response rate was 95% with a complete cutaneous response or a very good partial response rate (<1% skin involvement with patches or plaques) documented in 57% of the patients. Median duration of overall cutaneous response was 174 days (5.8 months; range: 60-675 days). TSEBT-related acute adverse events (grade 1 or 2) were observed in 60% of patients. Low-dose (10-Gy) TSEBT offers a high overall response rate and is relatively safe. With this approach, reirradiation at times of relapse or progression is likely to be less toxic than standard dose TSEBT. It remains to be established whether adjuvant and combination treatments can prolong the beneficial effects of low-dose TSEBT. Copyright © 2015 Elsevier Inc. All rights reserved.

Low-Dose (10-Gy) Total Skin Electron Beam Therapy for Cutaneous T-Cell Lymphoma: An Open Clinical Study and Pooled Data Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamstrup, Maria R., E-mail: mkam0004@bbh.regionh.dk; Gniadecki, Robert; Iversen, Lars

2015-05-01

Purpose: Cutaneous T-cell lymphomas (CTCLs) are dominated by mycosis fungoides (MF) and Sézary syndrome (SS), and durable disease control is a therapeutic challenge. Standard total skin electron beam therapy (TSEBT) is an effective skin-directed therapy, but the possibility of retreatments is limited to 2 to 3 courses in a lifetime due to skin toxicity. This study aimed to determine the clinical effect of low-dose TSEBT in patients with MF and SS. Methods and Materials: In an open clinical study, 21 patients with MF/SS stages IB to IV were treated with low-dose TSEBT over <2.5 weeks, receiving a total dose of 10 Gymore » in 10 fractions. Data from 10 of these patients were published previously but were included in the current pooled data analysis. Outcome measures were response rate, duration of response, and toxicity. Results: The overall response rate was 95% with a complete cutaneous response or a very good partial response rate (<1% skin involvement with patches or plaques) documented in 57% of the patients. Median duration of overall cutaneous response was 174 days (5.8 months; range: 60-675 days). TSEBT-related acute adverse events (grade 1 or 2) were observed in 60% of patients. Conclusions: Low-dose (10-Gy) TSEBT offers a high overall response rate and is relatively safe. With this approach, reirradiation at times of relapse or progression is likely to be less toxic than standard dose TSEBT. It remains to be established whether adjuvant and combination treatments can prolong the beneficial effects of low-dose TSEBT.« less

Exposure to Carbon Ions Triggers Proinflammatory Signals and Changes in Homeostasis and Epidermal Tissue Organization to a Similar Extent as Photons

PubMed Central

Simoniello, Palma; Wiedemann, Julia; Zink, Joana; Thoennes, Eva; Stange, Maike; Layer, Paul G.; Kovacs, Maximilian; Podda, Maurizio; Durante, Marco; Fournier, Claudia

2016-01-01

The increasing application of charged particles in radiotherapy requires a deeper understanding of early and late side effects occurring in skin, which is exposed in all radiation treatments. We measured cellular and molecular changes related to the early inflammatory response of human skin irradiated with carbon ions, in particular cell death induction and changes in differentiation and proliferation of epidermal cells during the first days after exposure. Model systems for human skin from healthy donors of different complexity, i.e., keratinocytes, coculture of skin cells, 3D skin equivalents, and skin explants, were used to investigate the alterations induced by carbon ions (spread-out Bragg peak, dose-averaged LET 100 keV/μm) in comparison to X-ray and UV-B exposure. After exposure to ionizing radiation, in none of the model systems, apoptosis/necrosis was observed. Carbon ions triggered inflammatory signaling and accelerated differentiation of keratinocytes to a similar extent as X-rays at the same doses. High doses of carbon ions were more effective than X-rays in reducing proliferation and inducing abnormal differentiation. In contrast, changes identified following low-dose exposure (≤0.5 Gy) were induced more effectively after X-ray exposure, i.e., enhanced proliferation and change in the polarity of basal cells. PMID:26779439

Time-course study of different innate immune mediators produced by UV-irradiated skin: comparative effects of short and daily versus a single harmful UV exposure.

PubMed

Cela, Eliana M; Friedrich, Adrian; Paz, Mariela L; Vanzulli, Silvia I; Leoni, Juliana; González Maglio, Daniel H

2015-05-01

The modulatory effects of solar UV radiation on the immune system have been widely studied. As the skin is the main target of UV radiation, our purpose was to compare the impact on skin innate immunity of two contrasting ways to be exposed to sunlight. Hairless mice were UV irradiated with a single high UV dose simulating a harmful exposure, or with repetitive low UV doses simulating short occasional daily exposures. Skin samples were taken at different times after UV irradiation to evaluate skin histology, inflammatory cell recruitment, epidermal T-cell population and the mitochondrial function of epidermal cells. The transcriptional profiles of pro-inflammatory cytokines, chemokines, antimicrobial peptides and Toll-like receptors were evaluated by RT-PCR and ELISA in tissue homogenates. Finally, a lymphangiography was performed to assess modification in the lymphatic vessel system. A single high UV dose produces a deep inflammatory state characterized by the production of pro-inflammatory cytokines and chemokines that, in turn, induces the recruitment of neutrophils and macrophages into the irradiated area. On the other hand, repetitive low UV doses drive the skin to a photo-induced alert state in which there is no sign of inflammation, but the epithelium undergoes changes in thickness, the lymphatic circulation increases, and the transcription of antimicrobial peptides is induced. © 2014 John Wiley & Sons Ltd.

Fractionated irradiation of carbon beam and the isoeffect dose on acute reaction of skin

PubMed Central

Uzawa, Akiko; Hirayama, Ryoichi; Matsumoto, Yoshitaka; Koda, Kana; Koike, Sachiko; Ando, Koichi; Furusawa, Yoshiya

2014-01-01

Purpose: The aim of this study was to clear any specific LETs cause change in skin reaction. We irradiated mice feet with mono-energetic and SOBP carbon ions, to obtain dose–response of early skin reaction at different LETs. Materials and methods: Mice: C3H/HeMsNrsf female mice aged 4 months old were used for this study. The animals were produced and maintained in specific pathogen-free (SPF) facilities. Irradiation: The mice right hind legs received daily fractionated irradiation ranged from single to six fractions. Carbon ions (12C6+) were accelerated by the HIMAC synchrotron to 290 MeV/u. Irradiation was conducted using horizontal carbon-ion beams with a dose rate of ∼3 Gy/min. We chose the LETs at entrance of plateau (20keV/μm) and the SOBP (proximal: 40 keV/μm, middle: 45 keV/μm, distal: 60 keV/μm, distal-end: 80 keV/μm). The reference beam was 137Cs gamma rays with a dose rate of 1.2 Gy/min. Skin reaction: Skin reaction of the irradiated legs was scored every other day, between the14th and 35th post-irradiation days. Our scoring scale consisted of seven steps, ranging from 0.5 to 3.5 [ 1]. The skin score analyzed a result by the method that described by Ando et al. [ 2]. The Fe-plot proposed by Douglas and Fowler was used as a multifraction linear quadratic model. A plot between the reciprocal of the isoeffect dose and the dose per fraction resulted in a straight line. Results: Required isoeffect total dose increased linearly with the fraction numbers on a semi-logarithmic chart at LET 20–60 keV/µm SOBP beam. The isoeffect total dose decreased with the increase in the LET. However, no increases in isoeffect total dose were observed at few fractionations at 80 keV/µm. (data not shown) Using an Fe-plot, we analyzed the isoeffect total dose to evaluate the dependence on Carbon beam, or gamma ray. When I irradiate it by gamma ray, an Fe-plot shows linearly. But, irradiated by Carbon beam, an Fe-plot bent at low fractions (Fig. 1). Conclusion: The LQ-model-based Fe-plot could not fit skin reaction at few fractions at high-LET. Clinical Trial Registration number if required: No.Fig. 1.The reciprocal of the isoeffect dose is plotted against the dose per fraction. (i) Gamma ray: Fe-plot was linear. (ii) C-ions: Fe-plot bent at low fractions.

The effect of skin moisture on the density distribution of OH and O close to the skin surface

NASA Astrophysics Data System (ADS)

Wu, F.; Li, J.; Liu, F.; Zhou, X.; Lu, X.

2018-03-01

OH radicals and O atoms are believed to be two of the most important reactive species in various biomedical applications of atmospheric pressure plasma jets. In this study, the effect of the skin moisture on the density distribution of OH and O close to the surface of the ex vivo pig skin is investigated by using laser-induced fluorescence technology. The skin moistures used in this study are 20%, 40%, 60%, and 80%, respectively. The experiment results indicate that, at a gas flow rate of 0.5 L/min, when the skin moisture is increased, the OH density close to the skin surface increases, while the O density decreases. On the other hand, when the gas flow rate is increased to 1 L/min, the OH density close to the skin surface is less sensitive with the moisture of the skin surface. Besides, when the skin moisture is 80%, the OH density increases with the increase in the concentration of H2O in the working gas and it reaches its maximum 7.9 × 1013 cm-3 when the concentration of H2O in the working gas is about 500 ppm. The OH density starts to decrease while the H2O concentration in the working gas keeps increasing. On the order hand, the O density shows a maximum 7.4 × 1014 cm-3 when the gas flow rate is 0.5 L/min with no O2 added and the skin moisture is 20%. But, when the gas flow rate is increased to about 1 to 2 L/min, the O density achieves its maximum when 0.5% of O2 is added to the working gas. The possible reasons for these observations are discussed.

A dose-response evaluation of rumen-protected niacin in thermoneutral or heat-stressed lactating Holstein cows.

PubMed

Rungruang, S; Collier, J L; Rhoads, R P; Baumgard, L H; de Veth, M J; Collier, R J

2014-01-01

Twenty-four multiparous high-producing dairy cows (40.0±1.4kg/d) were used in a factorial design to evaluate effects of 2 environments [thermoneutral (TN) and heat stress (HS)] and a dose range of dietary rumen-protected niacin (RPN; 0, 4, 8, or 12g/d) on body temperature, sweating rate, feed intake, water intake, production parameters, and blood niacin concentrations. Temperature-humidity index values during TN never exceeded 68 (stress threshold), whereas temperature-humidity index values during HS were above 68 for 24h/d. The HS environment increased hair coat and skin, rectal, and vaginal temperatures; respiration rate; skin and hair coat evaporative heat loss; and water intake and decreased DMI (3.5kg/d), milk yield (4.1kg/d), 4% fat-corrected milk (2.7kg/d), and milk protein yield (181.7g/d). Sweating rate increased during HS (12.7g/m(2) per h) compared with TN, but this increase was only 10% of that reported in summer-acclimated cattle. Niacin supplementation did not affect sweating rate, dry-matter intake, or milk yield in either environment. Rumen-protected niacin increased plasma and milk niacin concentrations in a linear manner. Heat stress reduced niacin concentration in whole blood (7.86 vs. 6.89μg/mL) but not in milk. Reduced blood niacin concentration was partially corrected by dietary RPN. An interaction existed between dietary RPN and environment; dietary RPN linearly increased water intake in both environments, but the increase was greater during HS conditions. Increasing dietary RPN did not influence skin temperatures. During TN, supplementing 12g/d of RPN increased hair coat (unshaved skin; 30.3 vs. 31.3°C at 1600h) but not shaved skin (32.8 vs. 32.9°C at 1600h) temperature when compared with 0g/d at all time points, whereas the maximum temperature (18°C) of the room was lower than skin temperature. These data suggest that dietary RPN increased water intake during both TN and HS and hair coat temperature during TN; however, core body temperature was unaffected. Thus, encapsulated niacin did not improve thermotolerance of winter-acclimated lactating dairy cows exposed to moderate thermal stress in Arizona. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Hydrogel-Forming Microneedle Arrays Allow Detection of Drugs and Glucose In Vivo: Potential for Use in Diagnosis and Therapeutic Drug Monitoring

PubMed Central

Caffarel-Salvador, Ester; Brady, Aaron J.; Eltayib, Eyman; Meng, Teng; Alonso-Vicente, Ana; Gonzalez-Vazquez, Patricia; Torrisi, Barbara M.; Vicente-Perez, Eva Maria; Mooney, Karen; Jones, David S.; Bell, Steven E. J.; McCoy, Colin P.; McCarthy, Helen O.; McElnay, James C.; Donnelly, Ryan F.

2015-01-01

We describe, for the first time the use of hydrogel-forming microneedle (MN) arrays for minimally-invasive extraction and quantification of drug substances and glucose from skin in vitro and in vivo. MN prepared from aqueous blends of hydrolysed poly(methyl-vinylether-co-maleic anhydride) (11.1% w/w) and poly(ethyleneglycol) 10,000 daltons (5.6% w/w) and crosslinked by esterification swelled upon skin insertion by uptake of fluid. Post-removal, theophylline and caffeine were extracted from MN and determined using HPLC, with glucose quantified using a proprietary kit. In vitro studies using excised neonatal porcine skin bathed on the underside by physiologically-relevant analyte concentrations showed rapid (5 min) analyte uptake. For example, mean concentrations of 0.16 μg/mL and 0.85 μg/mL, respectively, were detected for the lowest (5 μg/mL) and highest (35 μg/mL) Franz cell concentrations of theophylline after 5 min insertion. A mean concentration of 0.10 μg/mL was obtained by extraction of MN inserted for 5 min into skin bathed with 5 μg/mL caffeine, while the mean concentration obtained by extraction of MN inserted into skin bathed with 15 μg/mL caffeine was 0.33 μg/mL. The mean detected glucose concentration after 5 min insertion into skin bathed with 4 mmol/L was 19.46 nmol/L. The highest theophylline concentration detected following extraction from a hydrogel-forming MN inserted for 1 h into the skin of a rat dosed orally with 10 mg/kg was of 0.363 μg/mL, whilst a maximum concentration of 0.063 μg/mL was detected following extraction from a MN inserted for 1 h into the skin of a rat dosed with 5 mg/kg theophylline. In human volunteers, the highest mean concentration of caffeine detected using MN was 91.31 μg/mL over the period from 1 to 2 h post-consumption of 100 mg Proplus® tablets. The highest mean blood glucose level was 7.89 nmol/L detected 1 h following ingestion of 75 g of glucose, while the highest mean glucose concentration extracted from MN was 4.29 nmol/L, detected after 3 hours skin insertion in human volunteers. Whilst not directly correlated, concentrations extracted from MN were clearly indicative of trends in blood in both rats and human volunteers. This work strongly illustrates the potential of hydrogel-forming MN in minimally-invasive patient monitoring and diagnosis. Further studies are now ongoing to reduce clinical insertion times and develop mathematical algorithms enabling determination of blood levels directly from MN measurements. PMID:26717198

Skin testing only with penicillin G in children with a history of penicillin allergy.

PubMed

Picard, Matthieu; Paradis, Louis; Bégin, Philippe; Paradis, Jean; Des Roches, Anne

2014-07-01

The absence of commercially available penicilloyl-polylysine (PPL) for most of the last decade severely hampered the practice of penicillin allergy evaluation because skin testing without PPL is reported to have a poor negative predictive value (NPV). To determine the safety and NPV of skin testing without PPL using only penicillin G followed by a 3-dose graded challenge to the incriminated penicillin in children with a history of penicillin allergy. Patients evaluated for a history of penicillin allergy at the CHU Sainte-Justine Allergy Clinic between December 2006 and December 2009 were skin tested only with penicillin G and underwent a 3-dose graded challenge to the culprit penicillin if the skin test result was negative. Among 563 patients skin tested to penicillin G, 185 (33%) had a positive skin test result. These patients had a shorter interval between the initial reaction and skin testing compared with patients with a negative skin test result (P = .03). A total of 375 of 378 patients (99%) with a negative skin test result were challenged and 18 (4.8%) reacted, translating into a NPV of 95.2% (95% confidence interval [CI], 92.5%-97.1%). Three of 17 patients with a history of anaphylaxis and a negative skin test result reacted to challenge (NPV, 82.4%; 95% CI, 59.0-93.8%). All challenge reactions were mild and resolved promptly with treatment. Among children with a history of penicillin allergy, skin testing only with penicillin G followed by a 3-dose graded challenge to the incriminated penicillin is safe and yields a good NPV. This approach could be useful when PPL is unavailable. Copyright © 2014 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Optimization of a murine and human tissue model to recapitulate dermal and pulmonary features of systemic sclerosis

PubMed Central

Watanabe, Tomoya; Mlakar, Logan; Heywood, Jonathan; Malaab, Maya; Hoffman, Stanley

2017-01-01

The murine bleomycin (BLM)-induced fibrosis model is the most widely used in systemic sclerosis (SSc) studies. It has been reported that systemic delivery of BLM via continuous diffusion from subcutaneously implanted osmotic minipumps can cause fibrosis of the skin, lungs, and other internal organs. However, the mouse strain, dosage of BLM, administration period, and additional important features differ from one report to the next. In this study, by employing the pump model in C57BL/6J mice, we show a dose-dependent increase in lung fibrosis by day 28 and a transient increase in dermal thickness. Dermal thickness and the level of collagen in skin treated with high-dose BLM was significantly higher than in skin treated with low dose BLM or vehicle. A reduction in the thickness of the adipose layer was noted in both high and low dose groups at earlier time points suggesting that the loss of the fat layer precedes the onset of fibrosis. High-dose BLM also induced dermal fibrosis and increased expression of fibrosis-associated genes ex vivo in human skin, thus confirming and extending the in vivo findings, and demonstrating that a human organ culture model can be used to assess the effect of BLM on skin. In summary, our findings suggest that the BLM pump model is an attractive model to analyze the underlying mechanisms of fibrosis and test the efficacy of potential therapies. However, the choice of mouse strain, duration of BLM administration and dose must be carefully considered when using this model. PMID:28651005

Optimization of a murine and human tissue model to recapitulate dermal and pulmonary features of systemic sclerosis.

PubMed

Watanabe, Tomoya; Nishimoto, Tetsuya; Mlakar, Logan; Heywood, Jonathan; Malaab, Maya; Hoffman, Stanley; Feghali-Bostwick, Carol

2017-01-01

The murine bleomycin (BLM)-induced fibrosis model is the most widely used in systemic sclerosis (SSc) studies. It has been reported that systemic delivery of BLM via continuous diffusion from subcutaneously implanted osmotic minipumps can cause fibrosis of the skin, lungs, and other internal organs. However, the mouse strain, dosage of BLM, administration period, and additional important features differ from one report to the next. In this study, by employing the pump model in C57BL/6J mice, we show a dose-dependent increase in lung fibrosis by day 28 and a transient increase in dermal thickness. Dermal thickness and the level of collagen in skin treated with high-dose BLM was significantly higher than in skin treated with low dose BLM or vehicle. A reduction in the thickness of the adipose layer was noted in both high and low dose groups at earlier time points suggesting that the loss of the fat layer precedes the onset of fibrosis. High-dose BLM also induced dermal fibrosis and increased expression of fibrosis-associated genes ex vivo in human skin, thus confirming and extending the in vivo findings, and demonstrating that a human organ culture model can be used to assess the effect of BLM on skin. In summary, our findings suggest that the BLM pump model is an attractive model to analyze the underlying mechanisms of fibrosis and test the efficacy of potential therapies. However, the choice of mouse strain, duration of BLM administration and dose must be carefully considered when using this model.

[Dose and image quality in intraoral radiography].

PubMed

Hjardemaal, O

1991-11-01

The technique factors when performing intraoral X-ray exposures must be selected in such a way that sufficient diagnostic information is obtained at a reasonable patient dose. The Danish National Institute of Radiation Hygiene has performed a study comprising 32 dental X-ray sets. The mean value of the skin dose for a maxillary molar was 9.6 mGy and the value for the dental colleges 7.0 mGy. For a mandibular incisor the corresponding doses were 7.7 mGy and 3.6 mGy. After the conclusion of the mentioned study it has been part of the institute's inspection procedure for dental X-ray sets to measure patient skin doses. 243 measurements were performed and the mean value of the entrance skin dose was 6.5 mGy and the dose interval was 0.7-57 mGy. All doses are normalised to speed class D film. At 16% of the inspected sets films of speed class E were used. The remainder used class D films. The spread in doses cannot be explained by variation in equipment parameters alone but is to a high degree due to a combination of inappropriate film processing and exposure time. Interviews with staff in dental clinics confirm that films are frequently processed until the desired density is obtained by visual estimation. It is shown that the skin dose when using film of speed class D can be kept below 7 mGy for a mandibular incisor. Concluding is stated that film processing shall be performed in accordance with specifications from the manufacturer of the developer. Film of speed class E must be used. Finally must the exposure time be graduated according to the object exposed.

Monte Carlo investigation of backscatter point spread function for x-ray imaging examinations

NASA Astrophysics Data System (ADS)

Xiong, Zhenyu; Vijayan, Sarath; Rudin, Stephen; Bednarek, Daniel R.

2017-03-01

X-ray imaging examinations, especially complex interventions, may result in relatively high doses to the patient's skin inducing skin injuries. A method was developed to determine the skin-dose distribution for non-uniform x-ray beams by convolving the backscatter point-spread-function (PSF) with the primary-dose distribution to generate the backscatter distribution that, when added to the primary dose, gives the total-dose distribution. This technique was incorporated in the dose-tracking system (DTS), which provides a real-time color-coded 3D-mapping of skin dose during fluoroscopic procedures. The aim of this work is to investigate the variation of the backscatter PSF with different parameters. A backscatter PSF of a 1-mm x-ray beam was generated by EGSnrc Monte-Carlo code for different x-ray beam energies, different soft-tissue thickness above bone, different bone thickness and different entrance-beam angles, as well as for different locations on the SK-150 anthropomorphic head phantom. The results show a reduction of the peak scatter to primary dose ratio of 48% when X-ray beam voltage is increased from 40 keV to 120 keV. The backscatter dose was reduced when bone was beneath the soft tissue layer and this reduction increased with thinner soft tissue and thicker bone layers. The backscatter factor increased about 21% as the angle of incidence of the beam with the entrance surface decreased from 90° (perpendicular) to 30°. The backscatter PSF differed for different locations on the SK-150 phantom by up to 15%. The results of this study can be used to improve the accuracy of dose calculation when using PSF convolution in the DTS.

Acute Biological Effects of Simulating the Whole-Body Radiation Dose Distribution from a Solar Particle Event Using a Porcine Model

PubMed Central

Wilson, Jolaine M.; Sanzari, Jenine K.; Diffenderfer, Eric S.; Yee, Stephanie S.; Seykora, John T.; Maks, Casey; Ware, Jeffrey H.; Litt, Harold I.; Reetz, Jennifer A.; McDonough, James; Weissman, Drew; Kennedy, Ann R.; Cengel, Keith A.

2011-01-01

In a solar particle event (SPE), an unshielded astronaut would receive proton radiation with an energy profile that produces a highly inhomogeneous dose distribution (skin receiving a greater dose than internal organs). The novel concept of using megavoltage electron-beam radiation to more accurately reproduce both the total dose and the dose distribution of SPE protons and make meaningful RBE comparisons between protons and conventional radiation has been described previously. Here, Yucatan minipigs were used to determine the effects of a superficial, SPE-like proton dose distribution using megavoltage electrons. In these experiments, dose-dependent increases in skin pigmentation, ulceration, keratinocyte necrosis and pigment incontinence were observed. Five of 18 animals (one each exposed to 7.5 Gy and 12.5 Gy radiation and three exposed to 25 Gy radiation) developed symptomatic, radiation-associated pneumonopathy approximately 90 days postirradiation. The three animals from the highest dose group showed evidence of mycoplasmal pneumonia along with radiation pneumonitis. Moreover, delayed-type hypersensitivity was found to be altered, suggesting that superficial irradiation of the skin with ionizing radiation might cause immune dysfunction or dysregulation. In conclusion, using total doses, patterns of dose distribution, and dose rates that are compatible with potential astronaut exposure to SPE radiation, animals experienced significant toxicities that were qualitatively different from toxicities previously reported in pigs for homogeneously delivered radiation at similar doses. PMID:21859326

SU-F-T-449: Dosimetric Comparison of Acuros XB, Adaptive Convolve in Intensity Modulated Radiotherapy for Head and Neck Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uehara, R; Tachibana, H

Purpose: There have been several publications focusing on dose calculation in lung for a new dose calculation algorithm of Acuros XB (AXB). AXB could contribute to dose calculation for high-density media for bone and dental prosthesis rather than in lung. We compared the dosimetric performance of AXB, Adaptive Convolve (AC) in head and neck IMRT plans. Methods: In a phantom study, the difference in depth profile between AXB and AC was evaluated using Kodak EDR2 film sandwiched with tough water phantoms. 6 MV x-ray using the TrueBeam was irradiated. In a patient study, 20 head and neck IMRT plans hadmore » been clinically approved in Pinnacle3 and were transferred to Eclipse. Dose distribution was recalculated using AXB in Eclipse while maintaining AC-calculated monitor units and MLC sequence planned in Pinnacle. Subsequently, both the dose-volumetric data obtained using the two different calculation algorithms were compared. Results: The results in the phantom evaluation for the shallow area ahead of the build-up region shows over-dose for AXB and under-dose for AC, respectively. In the patient plans, AXB shows more hot spots especially around the high-density media than AC in terms of PTV (Max difference: 4.0%) and OAR (Max. difference: 1.9%). Compared to AC, there were larger dose deviations in steep dose gradient region and higher skin-dose. Conclusion: In head and neck IMRT plans, AXB and AC show different dosimetric performance for the regions inside the target volume around high-density media, steep dose gradient regions and skin-surface. There are limitations in skin-dose and complex anatomic condition using even inhomogeneous anthropomorphic phantom Thus, there is the potential for an increase of hot-spot in AXB, and an underestimation of dose in substance boundaries and skin regions in AC.« less

Comprehensive evaluation of broad-beam transmission of patient supports from three fluoroscopy-guided interventional systems.

PubMed

DeLorenzo, Matthew C; Yang, Kai; Li, Xinhua; Liu, Bob

2018-04-01

The purpose of the study was to measure, evaluate, and model the broad-beam x-ray transmission of the patient supports from representative modern fluoroscopy-guided interventional systems, for patient skin dose calculation. Broad-beam transmission was evaluated by varying incident angle, kVp, added copper (Cu) filter, and x-ray field size for three fluoroscopy systems: General Electric (GE) Innova 4100 with Omega V table and pad, Siemens Axiom Artis with Siemens tabletop "narrow" (CARD) table and pad, and Siemens Zeego with Trumpf TruSystem 7500 table and pad. Field size was measured on the table using a lead ruler for all setups in this study. Exposure rates were measured in service mode using a calibrated Radcal 10 × 6-60 ion chamber above the patient support at the assumed skin location. Broad-beam transmission factors were calculated by the ratio of air kerma rates measured with and without a patient support in the beam path. First, angle dependency was investigated on the GE system, with the chamber at isocenter, for angles of 0°, 15°, 30°, and 40°, for a variety of kVp, added Cu filters, and for two field sizes (small and large). Second, the broad-beam transmission factor at normal incidence was evaluated for all three fluoroscopes by varying kVp, added Cu filter, and field size (small, medium, and large). An analytical equation was created to fit the data as to maximize R 2 and minimize maximum percentage difference across all measurements for each system. For all patient supports, broad-beam transmission factor increased with field size, kVp, and added Cu filtration and decreased with incident angle. Oblique incidence measurements show that the transmission decreased by about 1%, 3%, and 6% for incident angles of 15°, 30°, and 40°, respectively. The broad-beam transmission factors at 0° for the table and table plus pad ranged from 0.73 to 0.96 and from 0.59 to 0.89, respectively. The GE and Siemens transmission factors were comparable, while the Trumpf transmission factors were the lowest. The data were successfully fitted to a function of angle, field size, kVp, and added Cu filtration using nine parameters, with an average R 2 value of 0.977 and maximum percentage difference of 4.08%. This study evaluated the broad-beam transmission for three representative fluoroscopy systems and their dependency on angle, kVp, added Cu filter, and field size. The comprehensive data provided for patient support transmission will facilitate accurate calculation of peak skin dose (PSD) and may potentially be integrated into real-time and retrospective dose monitoring with access to Radiation Dose Structured Reports (RDSR) and radiation event data. © 2018 American Association of Physicists in Medicine.

Study on the Effect of Thermal and Magnetic Stimulation by Measuring of the Peripheral Blood Flow and Skin Temperature

NASA Astrophysics Data System (ADS)

Kubota, Kouhei; Nuruki, Atsuo; Tamari, Youzou; Yunokuchi, Kazutomo

Recently, the stiff shoulder accompanying the muscle fatigue becomes an issue of public concern. Therefore, we paid attention to the effect of the thermal and magnetic stimulation for the muscle fatigue. The maximum voluntary contraction has recovered significantly, and also peripheral blood flow has increased by stimulation. In order to evaluate if the thermal and magnetic stimulation has any effects, three parameters was measured, which are the maximum voluntary contraction, peripheral blood flow and skin temperature. The skin temperature, however, did not changed significantly.

Radiation induced graft copolymerization of methyl methacrylate onto chrome-tanned pig skins

NASA Astrophysics Data System (ADS)

Pietrucha, K.; Pȩkala, W.; Kroh, J.

Graft copolymerization of methyl methacrylate (MMA) onto chrome-tanned pig skins was carried out by the irradiation with 60Co ?-rays. The grafted polymethyl methacrylate (PMMA) chains were isolated by acid hydrolysis of the collagen backbone in order to characterize the graft copolymers. Proof of grafting was obtained through the detection of amino acid endgroups in the isolated grafts by reaction with ninhydrin. The grafting yield of MMA in aqueous emulsion was found to be higher than that for pure MMA and MMA in acetone. The degree of grafting increases with increasing monomer concentration in emulsion and reaches maximum at radiation dose ca 15 kGy. The yield of grafting is very high - ca 90% of monomer converts into copolymer and only 10% is converted into homopolymer. The present paper reports the physical properties of chrome-tanned pig skins after graft polymerization with MMA in emulsion. Modified leathers are more resistant against water absorption and abrasion in comparison with unmodified ones. They have more uniform structure over the whole surface, greater thickness and stiffness. The results reported seem to indicate that MMA may be used in the production of shoe upper and sole leathers. The mechanism of some of the processes occuring during radiation grafting of MMA in water emulsion on tanned leathers has been also suggested and discussed.

Skin temperature increase mediated by wearable, long duration, low-intensity therapeutic ultrasound

NASA Astrophysics Data System (ADS)

Langer, Matthew D.; Huang, Wenyi; Ghanem, Angi; Guo, Yuan; Lewis, George K.

2017-03-01

One of the safety concerns with the delivery of therapeutic ultrasound is overheating of the transducer-skin interface due to poor or improper coupling. The objective of this research was to define a model that could be used to calculate the heating in the skin as a result of a novel, wearable long-duration ultrasound device. This model was used to determine that the maximum heating in the skin remained below the minimum threshold necessary to cause thermal injury over multiple hours of use. In addition to this model data, a human clinical study used wire thermocouples on the skin surface to measure heating characteristics during treatment with the sustained ultrasound system. Parametric analysis of the model determined that the maximum temperature increase is at the surface of the skin ranged from 40-41.8° C when perfusion was taken into account. The clinical data agreed well with the model predictions. The average steady state temperature observed across all 44 subjects was 40°C. The maximum temperature observed was less than 44° C, which is clinically safe for over 5 hours of human skin contact. The resultant clinical temperature data paired well with the model data suggesting the model can be used for future transducer and ultrasound system design simulation. As a result, the device was validated for thermal safety for typical users and use conditions.

Expression of Filaggrin and its Degradation Products in Human Skin Following Erythemal Doses of Ultraviolet B Irradiation.

PubMed

Simonsen, Stine; Thyssen, Jacob P; Heegaard, Steffen; Kezic, Sanja; Skov, Lone

2017-07-06

Epidermal filaggrin level is affected by ultraviolet B irradiation in animal and experimental models. This study examined the effect of ultraviolet B irradiation on epidermal filaggrin and natural moisturizing factors in vivo in healthy adults (n = 22). Participants were irradiated with 2 minimal erythema doses of ultraviolet B on the skin. Biopsies and tape strips were collected from skin irradiated 24 and 72 h earlier and from non-irradiated skin (control). Real-time quantitative PCR on skin biopsies showed significantly reduced profilaggrin mRNA expression 24 h after irradiation (mean relative mRNA expression ± standard deviation: control, 3.86 ± 2.06 vs. 24 h, 1.52 ± 0.640; p = 0.02; n = 8). Immunohistochemistry showed aberrant spatial distribution of filaggrin protein 72 h after irradiation (n = 3). High-pressure liquid chromatography of tape extracts showed no change in mean total natural moisturizing factor levels after irradiation, but mean trans-urocanic acid was significantly reduced, as expected (n = 8). In conclusion, erythemal doses of ultraviolet B exert acute effects on profilaggrin mRNA and filaggrin protein in human skin in vivo.

Intensity Modulated Radiation Therapy With Simultaneous Integrated Boost in Patients With Brain Oligometastases: A Phase 1 Study (ISIDE-BM-1)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferro, Marica; Chiesa, Silvia; Macchia, Gabriella, E-mail: gmacchia@rm.unicatt.it

Purpose: To investigate the maximum tolerated dose of intensity modulated radiation therapy simultaneous integrated boost whole-brain radiation therapy for palliative treatment of patients with <5 brain metastases using a standard linear accelerator. Materials and Methods: The whole brain plus 3-mm margin was defined as the planning target volume (PTV{sub wb}), whereas each brain metastasis, defined as the contrast-enhancing tumor on MRI T1 scans, plus a 3-mm isotropic margin, was defined as metastases PTV (PTV{sub m}). Radiation therapy was delivered in 10 daily fractions (2 weeks). Only the dose to PTV{sub m} was progressively increased in the patient cohorts (35 Gy, 40 Gy, 45 Gy, 50 Gy),more » whereas the PTV{sub wb} was always treated with 30 Gy (3 Gy per fraction) in all patients. The dose-limiting toxicity was evaluated providing that 3 months of follow-up had occurred after the treatment of a 6-patient cohort. Results: Thirty patients were enrolled in the study (dose PTV{sub m}: 35 Gy, 8 patients; 40 Gy, 6 patients; 45 Gy, 6 patients; 50 Gy, 10 patients). The number of treated brain metastases was 1 in 18 patients, 2 in 5 patients, 3 in 6 patients, and 4 in 1 patient. Three patients experienced dose-limiting toxicity: 1 patient at dose level 2 presented grade 3 (G3) skin toxicity; 1 patient at dose level 4 presented G3 neurologic toxicity; and 1 patient at the same level showed brain hemorrhage. Most patients showed G1 to 2 acute toxicity, in most cases skin (n=19) or neurologic (n=10). Twenty-seven were evaluable for response: 6 (22%) stable disease, 18 (67%) partial response, and 3 (11%) complete response. Median survival and 1-year overall survival were 12 months and 53%, respectively. No patient showed late toxicity. Conclusions: In this first prospective trial on the use of intensity modulated radiation therapy simultaneous integrated boost delivered with a standard linear accelerator in patients with brain oligometastases, a boost dose up to 50 Gy in 10 fractions was tolerable according to the study design.« less

SU-F-P-47: Estimation of Skin Dose by Performing the Measurements On Cylindrical Phantom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bosma, S; Sanders, M; Aryal, P

Purpose: To evaluate the skin dose by performing the measurements on cylindrical phantom with 6X beam. Methods: A cylindrical phantom was used to best model a patient surface. The source to surface distance (SSD) was 100 cm at phantom surface along central axis (CAX). The EBT2 films were cut into 2×2 cm2 pieces. Each piece of film was placed at CAX on phantom surface for each measurement at 0°, 15°, 30°, 45°, 60°, 75°, and 90° gantry angles for field sizes of 5×5, 10×10, 15×15, and 20×20 cm{sup 2} respectively. One hundred monitor units (MU) with 6X beam were deliveredmore » for each set up. Similarly, the measurements were repeated using lithium fluoride (LiF) thermoluminescent dosimeter (TLD) chips (1X1X1 mm{sup 3}). Two TLD chips were placed for each gantry angle and field size. The calibration curves were produced for both film and TLD. The computed tomography (CT) was also performed on the same cylindrical phantom and dose was evaluated at the phantom surface using Eclipse treatment planning system ( AAA algorithm) for skin dose comparison. Results: Data showed small differences at smaller angles among EBT2, TLD and Eclipse treatment planning system. But Eclipse treatment planning system under estimated the skin dose between 20% and 50% at larger gantry angles (between 40° and 80°) at all field sizes before dose differences began to converge. Conclusion: Given this data, we can conclude that Eclipse treatment planning system under estimated the dose especially between 40 and 80 degrees of obliquity compared to the measurements results. Ideally, this study can be applied largely to head and neck patients where contours differ drastically and where skin dose is paramount.« less

SU-E-T-777: Use of Tennis Racket and Air Gap Between the Body and Carbon Fiber Couch for Skin Sparing in Radiation Therapy of Prone Breast

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lief, E

2015-06-15

Purpose: To reduce the skin dose from the carbon fiber couch scatter in radiation treatment of breast cancer in the prone position. If this issue is not addressed, the prone breast touching the solid carbon fiber couch can absorb significant dose to the skin and cause the skin reaction. Methods: 1. Use of “tennis racket” instead of the solid couch. To check this hypothesis, we measured the dose at the depth of 5 mm in solid water phantom placed on the couch, using a Farmer chamber. A plan for a patient with 6MV beams, gantry angles of 113 and 286more » degrees Varian scale was used. It was found that treatment with “tennis racket” instead of the solid carbon fiber couch reduces the surface dose by 5–7%, depending on the beam direction. 2. Use of the air gap between the couch and the body was analyzed using radiochromic film on the surface of the solid water phantom 10 cm thick. Initially the phantom was placed on the couch with the film sandwiched in between. Two fields at the angles of 135 and 315 degrees were used. The measurements were repeated for the air gap of 2 and 5 cm and 6 and 15 MV beams. Results: It was found that a 2-cm gap decreased the surface dose by 3% for a 6 MV beam and by 5.5% for a 15 MV beam. A 5-cm gap reduced the dose by 9% for 6 MV and 13.5% for 15 MV. Conclusion: Use of both methods (combined if possible) can significantly reduce the surface dose in radiation therapy of the prone breast and possible skin reaction. We plan to explore dependence of the dose reduction upon the angle of incidence.« less

Feasibility of a semiconductor dosimeter to monitor skin dose in interventional radiology.

PubMed

Meyer, P; Regal, R; Jung, M; Siffert, P; Mertz, L; Constantinesco, A

2001-10-01

The design and preliminary test results of a semiconductor silicon dosimeter are presented in this article. Use of this dosimeter is foreseen for real-time skin dose control in interventional radiology. The strong energy dependence of this kind of radiation detector is well overcome by filtering the silicon diode. Here, the optimal filter features have been calculated by numerical Monte Carlo simulations. A prototype has been built and tested in a radiological facility. The first experimental results show a good match between the filtered semiconductor diode response and an ionization chamber response, within 2% fluctuation in a 2.2 to 4.1 mm Al half-value layer (HVL) energy range. Moreover, the semiconductor sensor response is linear from 0.02 Gy/min to at least 6.5 Gy/min, covering the whole dose rate range found in interventional radiology. The results show that a semiconductor dosimeter could be used to monitor skin dose during the majority of procedures using x-rays below 150 keV. The use of this device may assist in avoiding radiation-induced skin injuries and lower radiation levels during interventional procedures.

A feasibility study of a deuterium-deuterium neutron generator-based boron neutron capture therapy system for treatment of brain tumors.

PubMed

Hsieh, Mindy; Liu, Yingzi; Mostafaei, Farshad; Poulson, Jean M; Nie, Linda H

2017-02-01

Boron neutron capture therapy (BNCT) is a binary treatment modality that uses high LET particles to achieve tumor cell killing. Deuterium-deuterium (DD) compact neutron generators have advantages over nuclear reactors and large accelerators as the BNCT neutron source, such as their compact size, low cost, and relatively easy installation. The purpose of this study is to design a beam shaping assembly (BSA) for a DD neutron generator and assess the potential of a DD-based BNCT system using Monte Carlo (MC) simulations. The MC model consisted of a head phantom, a DD neutron source, and a BSA. The head phantom had tally cylinders along the centerline for computing neutron and photon fluences and calculating the dose as a function of depth. The head phantom was placed at 4 cm from the BSA. The neutron source was modeled to resemble the source of our current DD neutron generator. A BSA was designed to moderate and shape the 2.45-MeV DD neutrons to the epithermal (0.5 eV to 10 keV) range. The BSA had multiple components, including moderator, reflector, collimator, and filter. Various materials and configurations were tested for each component. Each BSA layout was assessed in terms of the in-air and in-phantom parameters. The maximum brain dose was limited to 12.5 Gray-Equivalent (Gy-Eq) and the skin dose to 18 Gy-Eq. The optimized BSA configuration included 30 cm of lead for reflector, 45 cm of LiF, and 10 cm of MgF 2 for moderator, 10 cm of lead for collimator, and 0.1 mm of cadmium for thermal neutron filter. Epithermal flux at the beam aperture was 1.0 × 10 5  n epi /cm 2 -s; thermal-to-epithermal neutron ratio was 0.05; fast neutron dose per epithermal was 5.5 × 10 -13  Gy-cm 2 /φ epi , and photon dose per epithermal was 2.4 × 10 -13  Gy-cm 2 /φ epi . The AD, AR, and the advantage depth dose rate were 12.1 cm, 3.7, and 3.2 × 10 -3  cGy-Eq/min, respectively. The maximum skin dose was 0.56 Gy-Eq. The DD neutron yield that is needed to irradiate in reasonable time was 4.9 × 10 13  n/s. Results demonstrated that a DD-based BNCT system could be designed to produce neutron beams that have acceptable in-air and in-phantom characteristics. The parameter values were comparable to those of existing BNCT facilities. Continuing efforts are ongoing to improve the DD neutron yield. © 2016 American Association of Physicists in Medicine.

Three dimensional intensity modulated brachytherapy (IMBT): dosimetry algorithm and inverse treatment planning.

PubMed

Shi, Chengyu; Guo, Bingqi; Cheng, Chih-Yao; Esquivel, Carlos; Eng, Tony; Papanikolaou, Niko

2010-07-01

The feasibility of intensity modulated brachytherapy (IMBT) to improve dose conformity for irregularly shaped targets has been previously investigated by researchers by means of using partially shielded sources. However, partial shielding does not fully explore the potential of IMBT. The goal of this study is to introduce the concept of three dimensional (3D) intensity modulated brachytherapy and solve two fundamental issues regarding the application of 3D IMBT treatment planning: The dose calculation algorithm and the inverse treatment planning method. A 3D IMBT treatment planning system prototype was developed using the MATLAB platform. This system consists of three major components: (1) A comprehensive IMBT source calibration method with dosimetric inputs from Monte Carlo (EGSnrc) simulations; (2) a "modified TG-43" (mTG-43) dose calculation formalism for IMBT dosimetry; and (3) a physical constraint based inverse IMBT treatment planning platform utilizing a simulated annealing optimization algorithm. The model S700 Axxent electronic brachytherapy source developed by Xoft, Inc. (Fremont, CA), was simulated in this application. Ten intracavitary accelerated partial breast irradiation (APBI) cases were studied. For each case, an "isotropic plan" with only optimized source dwell time and a fully optimized IMBT plan were generated and compared to the original plan in various dosimetric aspects, such as the plan quality, planning, and delivery time. The issue of the mechanical complexity of the IMBT applicator is not addressed in this study. IMBT approaches showed superior plan quality compared to the original plans and tht isotropic plans to different extents in all studied cases. An extremely difficult case with a small breast and a small distance to the ribs and skin, the IMBT plan minimized the high dose volume V200 by 16.1% and 4.8%, respectively, compared to the original and the isotropic plans. The conformity index for the target was increased by 0.13 and 0.04, respectively. The maximum dose to the skin was reduced by 56 and 28 cGy, respectively, per fraction. Also, the maximum dose to the ribs was reduced by 104 and 96 cGy, respectively, per fraction. The mean dose to the ipsilateral and contralateral breasts and lungs were also slightly reduced by the IMBT plan. The limitations of IMBT are the longer planning and delivery time. The IMBT plan took around 2 h to optimize, while the isotropic plan optimization could reach the global minimum within 5 min. The delivery time for the IMBT plan is typically four to six times longer than the corresponding isotropic plan. In this study, a dosimetry method for IMBT sources was proposed and an inverse treatment planning system prototype for IMBT was developed. The improvement of plan quality by 3D IMBT was demonstrated using ten APBI case studies. Faster computers and higher output of the source can further reduce plan optimization and delivery time, respectively.

The effect of low dose ionizing radiation on homeostasis and functional integrity in an organotypic human skin model

DOE Office of Scientific and Technical Information (OSTI.GOV)

von Neubeck, Claere; Geniza, Matthew; Kauer, Paula M.

Outside the protection of earth’s atmosphere, astronauts are exposed to low doses of high linear energy transfer (LET) radiation. Future NASA plans for deep space missions or a permanent settlement on the moon are limited by the health risks associated with space radiation exposures. There is a paucity of direct epidemiological data for low dose exposures to space radiation-relevant high LET ions. Health risk models are used to estimate the risk for such exposures, though these models are based on high dose experiments. There is increasing evidence, however, that low and high dose exposures result in different signaling events atmore » the molecular level, and may involve different response mechanisms. Further, despite their low abundance, high LET particles have been identified as the major contributor to health risk during manned space flight. The human skin is exposed in every external radiation scenario, making it an ideal epithelial tissue model in which to study radiation induced effects. Here, we exposed an in vitro three dimensional (3-D) human organotypic skin tissue model to low doses of high LET oxygen (O), silicon (Si) and iron (Fe) ions. We measured proliferation and differentiation profiles in the skin tissue and examined the integrity of the skin’s barrier function. We discuss the role of secondary particles in changing the proportion of cells receiving a radiation dose, emphasizing the possible impact on radiation-induced health issues in astronauts.« less

Single dose irradiation response of pig skin: a comparison of brachytherapy using a single, high dose rate iridium-192 stepping source with 200 kV X-rays.

PubMed

Hamm, P C; Bakker, E J; van den Berg, A P; van den Aardweg, G J; Visser, A G; Levendag, P C

2000-07-01

An experimental brachytherapy model has been developed to study acute and late normal tissue reactions as a tool to examine the effects of clinically relevant multifractionation schedules. Pig skin was used as a model since its morphology, structure, cell kinetics and radiation-induced responses are similar to human skin. Brachytherapy was performed using a microSelectron high dose rate (HDR) afterloading machine with a single stepping source and a custom-made template. In this study the acute epidermal reactions of erythema and moist desquamation and the late dermal reactions of dusky mauve erythema and necrosis were evaluated after single doses of irradiation over a follow-up period of 16 weeks. The major aims of this work were: (a) to compare the effects of iridium-192 (192Ir) irradiation with effects after X-irradiation; (b) to compare the skin reactions in Yorkshire and Large White pigs; and (c) to standardize the methodology. For 192Ir irradiation with 100% isodose at the skin surface, the 95% isodose was estimated at the basal membrane, while the 80% isodose covered the dermal fat layers. After HDR 192Ir irradiation of Yorkshire pig skin the ED50 values (95% isodose) for moderate/severe erythema and moist desquamation were 24.8 Gy and 31.9 Gy, respectively. The associated mean latent period (+/- SD) was 39 +/- 7 days for both skin reactions. Late skin responses of dusky mauve erythema and dermal necrosis were characterized by ED50 values (80% isodose) of 16.3 Gy and 19.5 Gy, with latent periods of 58 +/- 7 days and 76 +/- 12 days, respectively. After X-irradiation, the incidence of the various skin reactions and their latent periods were similar. Acute and late reactions were well separated in time. The occurrence of skin reactions and the incidence of effects were comparable in Yorkshire and Large White pigs for both X-irradiation and HDR 192Ir brachytherapy. This pig skin model is feasible for future studies on clinically relevant multifractionation schedules in a brachytherapy setting.

Further development of LLNA:DAE method as stand-alone skin-sensitization testing method and applied for evaluation of relative skin-sensitizing potency between chemicals.

PubMed

Yamashita, Kunihiko; Shinoda, Shinsuke; Hagiwara, Saori; Itagaki, Hiroshi

2015-04-01

To date, there has been no well-established local lymph node assay (LLNA) that includes an elicitation phase. Therefore, we developed a modified local lymph node assay with an elicitation phase (LLNA:DAE) to discriminate true skin sensitizers from chemicals that gave borderline positive results and previously reported this assay. To develop the LLNA:DAE method as a useful stand-alone testing method, we investigated the complete procedure for the LLNA:DAE method using hexyl cinnamic aldehyde (HCA), isoeugenol, and 2,4-dinitrochlorobenzene (DNCB) as test compounds. We defined the LLNA:DAE procedure as follows: in the dose-finding test, four concentrations of chemical applied to dorsum of the right ear on days 1, 2, and 3 and dorsum of both ears on day 10. Ear thickness and skin irritation score were measured on days 1, 3, 5, 10, and 12. Local lymph nodes were excised and weighed on day 12. The test dose for the primary LLNA:DAE study was selected as the dose that gave the highest left ear lymph node weight in the dose-finding study, or the lowest dose that produced a left ear lymph node of over 4 mg. This procedure was validated using nine different chemicals. Furthermore, qualitative relationship was observed between the degree of elicitation response in the left ear lymph node and the skin sensitizing potency of 32 chemicals tested in this study and the previous study. These results indicated that LLNA:DAE method was as first LLNA method that was able to evaluate the skin sensitizing potential and potency in elicitation response.

The effects of a moderate and high dose of vitamin C on wound healing in a controlled guinea pig model.

PubMed

Silverstein, R J; Landsman, A S

1999-01-01

The purpose of this pilot study was to investigate the effect of vitamin C on wound healing in a controlled animal study. Twenty male guinea pigs were divided into two groups and were maintained on one of two commercially prepared diets: 1) supplemented with a moderate dose of vitamin C, or 2) supplemented with a high dose of vitamin C. After 6 weeks, a dorsal incision was made on the back of each of the animals. The incision was closed by primary intention as the animals continued on their respective diets until they were sacrificed. At the time of testing, either 10 days or 21 days postoperatively, the animals' skin was excised around the original incision using a metal template. A second skin sample was excised from each animal from an area adjacent to the original skin incision. This was done in order to determine the breaking force of the intact unaffected skin. Tension studies were performed to measure and compare the integrity and strength of the healing incisions. Biopsies were also sent for histopathologic analysis. The study presented here focused on whether or not increases in dietary vitamin C may improve the strength of a skin wound postoperatively. Although the sample size was small, the data suggest that a trend may exist in which increased vitamin C intake prior to and after surgery may result in faster recovery of skin integrity and strength across the wound. Although the difference between the groups is not statistically significant, the data clearly indicate that the animals receiving the higher dose of vitamin C demonstrated greater wound integrity than those receiving the moderate dose of the vitamin.

[Creation of a crystalline lens radiation exposure defense cover and the effect of radiation exposure decrease on neuro-interventions].

PubMed

Take, Toshio; Sato, Kaori; Kiuchi, Katsunori; Nakazawa, Yasuo

2007-11-20

A variety of radiation hazards resulting from interventional radiology (IVR) have been reported in recent years. Particularly affected are the skin and the crystalline lens, with their high radiation sensitivity. During neurological interventions, the radiological technologist should consider decreasing radiation exposure. We found exposure projections where the exposure dose became a radiation hazard for the crystalline lens, and examined an efficient method of cover for the exposure projections used for neurological interventions. The exposure projection for maximum crystalline lens radiation exposure was a lateral projection. In the crystalline lens the maximum exposure to radiation was on the X-ray tube side. The method of defense adopted was that of installing a lead plate of the appropriate shape on the surface of the X-ray tube collimator. In other exposure projections, this cover did not become a redundant shadow. With the cover that was created, the X-ray side crystalline lens lateral projection could be defended effectively.

Measuring dose from radiotherapy treatments in the vicinity of a cardiac pacemaker.

PubMed

Peet, Samuel C; Wilks, Rachael; Kairn, Tanya; Crowe, Scott B

2016-12-01

This study investigated the dose absorbed by tissues surrounding artificial cardiac pacemakers during external beam radiotherapy procedures. The usefulness of out-of-field reference data, treatment planning systems, and skin dose measurements to estimate the dose in the vicinity of a pacemaker was also examined. Measurements were performed by installing a pacemaker onto an anthropomorphic phantom, and using radiochromic film and optically stimulated luminescence dosimeters to measure the dose in the vicinity of the device during the delivery of square fields and clinical treatment plans. It was found that the dose delivered in the vicinity of the cardiac device was unevenly distributed both laterally and anteroposteriorly. As the device was moved distally from the square field, the dose dropped exponentially, in line with out-of-field reference data in the literature. Treatment planning systems were found to substantially underestimate the dose for volumetric modulated arc therapy, helical tomotherapy, and 3D conformal treatments. The skin dose was observed to be either greater or lesser than the dose received at the depth of the device, depending on the treatment site, and so care should be if skin dose measurements are to be used to estimate the dose to a pacemaker. Square field reference data may be used as an upper estimate of absorbed dose per monitor unit in the vicinity of a cardiac device for complex treatments involving multiple gantry angles. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Dose delivered from Varian's CBCT to patients receiving IMRT for prostate cancer.

PubMed

Wen, Ning; Guan, Huaiqun; Hammoud, Rabih; Pradhan, Deepak; Nurushev, T; Li, Shidong; Movsas, Benjamin

2007-04-21

With the increased use of cone beam CT (CBCT) for daily patient setup, the accumulated dose from CBCT may be significantly higher than that from simulation CT or portal imaging. The objective of this work is to measure the dose from daily pelvic scans with fixed technical settings and collimations. CBCT scans were acquired in half-fan mode using a half bowtie and x-rays were delivered in pulsed-fluoro mode. The skin doses for seven prostate patients were measured on an IRB-approved protocol. TLD capsules were placed on the patient's skin at the central axis of three beams: AP, left lateral (Lt Lat) and right lateral (Rt Lat). To avoid the ring artefacts centred in the prostate, the treatment couch was dropped 3 cm from the patient's tattoo (central axis). The measured AP skin doses ranged 3-6 cGy for 20-33 cm separation. The larger the patient size the less the AP skin dose. Lateral doses did not change much with patient size. The Lt Lat dose was approximately 4.0 cGy, which was approximately 40% higher than the Rt Lat dose of approximately 2.6 cGy. To verify this dose asymmetry, surface doses on an IMRT QA phantom (oval shaped, 30 cm x 20 cm) were measured at the same three sites using TLD capsules with 3 cm table-drop. The dose asymmetry was due to: (1) kV source rotation which always starts from the patient's Lt Lat and ends at Lt Lat. Gantry rotation gets much slower near the end of rotation but dose rate stays constant and (2) 370 degrees scan rotation (10 degrees scan overlap on the Lt Lat side). In vivo doses were measured inside a Rando pelvic heterogeneous phantom using TLDs. The left hip (femoral head and neck) received the highest doses of approximately 10-11 cGy while the right hip received approximately 6-7 cGy. The surface and in vivo doses were also measured for phantoms at the central-axis setup. The difference was less than approximately 12% to the table-drop setup.

Dose delivered from Varian's CBCT to patients receiving IMRT for prostate cancer

NASA Astrophysics Data System (ADS)

Wen, Ning; Guan, Huaiqun; Hammoud, Rabih; Pradhan, Deepak; Nurushev, T.; Li, Shidong; Movsas, Benjamin

2007-04-01

With the increased use of cone beam CT (CBCT) for daily patient setup, the accumulated dose from CBCT may be significantly higher than that from simulation CT or portal imaging. The objective of this work is to measure the dose from daily pelvic scans with fixed technical settings and collimations. CBCT scans were acquired in half-fan mode using a half bowtie and x-rays were delivered in pulsed-fluoro mode. The skin doses for seven prostate patients were measured on an IRB-approved protocol. TLD capsules were placed on the patient's skin at the central axis of three beams: AP, left lateral (Lt Lat) and right lateral (Rt Lat). To avoid the ring artefacts centred in the prostate, the treatment couch was dropped 3 cm from the patient's tattoo (central axis). The measured AP skin doses ranged 3-6 cGy for 20-33 cm separation. The larger the patient size the less the AP skin dose. Lateral doses did not change much with patient size. The Lt Lat dose was ~4.0 cGy, which was ~40% higher than the Rt Lat dose of ~2.6 cGy. To verify this dose asymmetry, surface doses on an IMRT QA phantom (oval shaped, 30 cm × 20 cm) were measured at the same three sites using TLD capsules with 3 cm table-drop. The dose asymmetry was due to: (1) kV source rotation which always starts from the patient's Lt Lat and ends at Lt Lat. Gantry rotation gets much slower near the end of rotation but dose rate stays constant and (2) 370° scan rotation (10° scan overlap on the Lt Lat side). In vivo doses were measured inside a Rando pelvic heterogeneous phantom using TLDs. The left hip (femoral head and neck) received the highest doses of ~10-11 cGy while the right hip received ~6-7 cGy. The surface and in vivo doses were also measured for phantoms at the central-axis setup. The difference was less than ~12% to the table-drop setup.

Clinical Significance of Accounting for Tissue Heterogeneity in Permanent Breast Seed Implant Brachytherapy Planning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mashouf, Shahram; Department of Radiation Oncology, Sunnybrook Odette Cancer Centre, Toronto, Ontario; Fleury, Emmanuelle

Purpose: The inhomogeneity correction factor (ICF) method provides heterogeneity correction for the fast calculation TG43 formalism in seed brachytherapy. This study compared ICF-corrected plans to their standard TG43 counterparts, looking at their capacity to assess inadequate coverage and/or risk of any skin toxicities for patients who received permanent breast seed implant (PBSI). Methods and Materials: Two-month postimplant computed tomography scans and plans of 140 PBSI patients were used to calculate dose distributions by using the TG43 and the ICF methods. Multiple dose-volume histogram (DVH) parameters of clinical target volume (CTV) and skin were extracted and compared for both ICF and TG43more » dose distributions. Short-term (desquamation and erythema) and long-term (telangiectasia) skin toxicity data were available on 125 and 110 of the patients, respectively, at the time of the study. The predictive value of each DVH parameter of skin was evaluated using the area under the receiver operating characteristic (ROC) curve for each toxicity endpoint. Results: Dose-volume histogram parameters of CTV, calculated using the ICF method, showed an overall decrease compared to TG43, whereas those of skin showed an increase, confirming previously reported findings of the impact of heterogeneity with low-energy sources. The ICF methodology enabled us to distinguish patients for whom the CTV V{sub 100} and V{sub 90} are up to 19% lower compared to TG43, which could present a risk of recurrence not detected when heterogeneity are not accounted for. The ICF method also led to an increase in the prediction of desquamation, erythema, and telangiectasia for 91% of skin DVH parameters studied. Conclusions: The ICF methodology has the advantage of distinguishing any inadequate dose coverage of CTV due to breast heterogeneity, which can be missed by TG43. Use of ICF correction also led to an increase in prediction accuracy of skin toxicities in most cases.« less

Clinical Significance of Accounting for Tissue Heterogeneity in Permanent Breast Seed Implant Brachytherapy Planning.

PubMed

Mashouf, Shahram; Fleury, Emmanuelle; Lai, Priscilla; Merino, Tomas; Lechtman, Eli; Kiss, Alex; McCann, Claire; Pignol, Jean-Philippe

2016-03-15

The inhomogeneity correction factor (ICF) method provides heterogeneity correction for the fast calculation TG43 formalism in seed brachytherapy. This study compared ICF-corrected plans to their standard TG43 counterparts, looking at their capacity to assess inadequate coverage and/or risk of any skin toxicities for patients who received permanent breast seed implant (PBSI). Two-month postimplant computed tomography scans and plans of 140 PBSI patients were used to calculate dose distributions by using the TG43 and the ICF methods. Multiple dose-volume histogram (DVH) parameters of clinical target volume (CTV) and skin were extracted and compared for both ICF and TG43 dose distributions. Short-term (desquamation and erythema) and long-term (telangiectasia) skin toxicity data were available on 125 and 110 of the patients, respectively, at the time of the study. The predictive value of each DVH parameter of skin was evaluated using the area under the receiver operating characteristic (ROC) curve for each toxicity endpoint. Dose-volume histogram parameters of CTV, calculated using the ICF method, showed an overall decrease compared to TG43, whereas those of skin showed an increase, confirming previously reported findings of the impact of heterogeneity with low-energy sources. The ICF methodology enabled us to distinguish patients for whom the CTV V100 and V90 are up to 19% lower compared to TG43, which could present a risk of recurrence not detected when heterogeneity are not accounted for. The ICF method also led to an increase in the prediction of desquamation, erythema, and telangiectasia for 91% of skin DVH parameters studied. The ICF methodology has the advantage of distinguishing any inadequate dose coverage of CTV due to breast heterogeneity, which can be missed by TG43. Use of ICF correction also led to an increase in prediction accuracy of skin toxicities in most cases. Copyright © 2016 Elsevier Inc. All rights reserved.

The influence of alcohol, propylene glycol and 1,2-pentanediol on the permeability of hydrophilic model drug through excised pig skin.

PubMed

Duracher, Lucie; Blasco, Laurent; Hubaud, Jean-Claude; Vian, Laurence; Marti-Mestres, Gilberte

2009-06-05

Alcohol and glycol including 1,2-pentanediol, a new product in this field, were examined for their transdermal penetration enhancing in vitro properties using pig skin and caffeine as a model drug. In order to investigate a possible influence of these compounds, we followed diffusion from an aqueous solution with caffeine followed by a series of different vehicles, their compositions were: (1) in water as a control; (2) in propylene glycol/ethanol/water (25:25:48; v/v/v); (3) in 1,2-pentanediol/water (2.5:95.5, v/v); (4) in 1,2-pentanediol/water (5:93, v/v); in propylene glycol/water (5:93; v/v); and in ethanol/water (5:93; v/v). The stratum corneum/vehicle partition coefficients (K(m)), maximum flux (J), enhancement factor (EF), 24-h receptor concentration (Q(24h)) were determined and compared to control values (caffeine in water). Permeation was also expressed in percentage of the applied dose absorbed in the different compartments. In all test models, caffeine was released and penetrated into pig skin. The 1,2-pentanediol was presented as the most effective enhancer; with a low proportion of this compound (only 5%), caffeine penetrated the skin quicker and in a greater extent. While this compound showed promise as penetration enhancer, further study was required to determine its effectiveness with others drugs and its irritation potential.

Effect of Microalgal Extracts of Tetraselmis suecica against UVB-Induced Photoaging in Human Skin Fibroblasts.

PubMed

Jo, Wol Soon; Yang, Kwang Mo; Park, Hee Sung; Kim, Gi Yong; Nam, Byung Hyouk; Jeong, Min Ho; Choi, Yoo Jin

2012-12-01

Exposure of cells to ultraviolet B (UVB) radiation can induce production of free radicals and reactive oxygen species (ROS), which damage cellular components. In addition, these agents can stimulate the expression of matrix metalloproteinase (MMP) and decrease collagen synthesis in human skin cells. In this study, we examined the anti-photoaging effects of extracts of Tetraselmis suecica (W-TS). W-TS showed the strongest scavenging activity against 2,2-difenyl-1-picrylhydrazyl (DPPH) and peroxyl radicals, followed by superoxide anions from the xanthine/xanthine oxidase system. We observed that the levels of both intracellular ROS and lipid peroxidation significantly increased in UVB-irradiated human skin fibroblast cells. Furthermore, the activities of enzymatic antioxidants (e.g., superoxide dismutase) and the levels of non-enzymatic antioxidants (e.g., glutathione) significantly decreased in cells. However, W-TS pretreatment, at the maximum tested concentration, significantly decreased intracellular ROS and malondialdehyde (MDA) levels, and increased superoxide dismutase and glutathione levels in the cells. At this same concentration, W-TS did not show cytotoxicity. Type 1 procollagen and MMP-1 released were quantified using RT-PCR techniques. The results showed that W-TS protected type 1 procollagen against UVBinduced depletion in fibroblast cells in a dose-dependent manner via inhibition of UVB-induced MMP-1. Taken together, the results of the study suggest that W-TS effectively inhibits UVB-induced photoaging in skin fibroblasts by its strong anti-oxidant ability.

Effect of Microalgal Extracts of Tetraselmis suecica against UVB-Induced Photoaging in Human Skin Fibroblasts

PubMed Central

Jo, Wol Soon; Yang, Kwang Mo; Park, Hee Sung; Kim, Gi Yong; Nam, Byung Hyouk

2012-01-01

Exposure of cells to ultraviolet B (UVB) radiation can induce production of free radicals and reactive oxygen species (ROS), which damage cellular components. In addition, these agents can stimulate the expression of matrix metalloproteinase (MMP) and decrease collagen synthesis in human skin cells. In this study, we examined the anti-photoaging effects of extracts of Tetraselmis suecica (W-TS). W-TS showed the strongest scavenging activity against 2,2-difenyl-1-picrylhydrazyl (DPPH) and peroxyl radicals, followed by superoxide anions from the xanthine/xanthine oxidase system. We observed that the levels of both intracellular ROS and lipid peroxidation significantly increased in UVB-irradiated human skin fibroblast cells. Furthermore, the activities of enzymatic antioxidants (e.g., superoxide dismutase) and the levels of non-enzymatic antioxidants (e.g., glutathione) significantly decreased in cells. However, W-TS pretreatment, at the maximum tested concentration, significantly decreased intracellular ROS and malondialdehyde (MDA) levels, and increased superoxide dismutase and glutathione levels in the cells. At this same concentration, W-TS did not show cytotoxicity. Type 1 procollagen and MMP-1 released were quantified using RT-PCR techniques. The results showed that W-TS protected type 1 procollagen against UVBinduced depletion in fibroblast cells in a dose-dependent manner via inhibition of UVB-induced MMP-1. Taken together, the results of the study suggest that W-TS effectively inhibits UVB-induced photoaging in skin fibroblasts by its strong anti-oxidant ability. PMID:24278616

Spot-Scanning Proton Arc (SPArc) Therapy: The First Robust and Delivery-Efficient Spot-Scanning Proton Arc Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, Xuanfeng, E-mail: Xuanfeng.ding@beaumont.org; Li, Xiaoqiang; Zhang, J. Michele

Purpose: To present a novel robust and delivery-efficient spot-scanning proton arc (SPArc) therapy technique. Methods and Materials: A SPArc optimization algorithm was developed that integrates control point resampling, energy layer redistribution, energy layer filtration, and energy layer resampling. The feasibility of such a technique was evaluated using sample patients: 1 patient with locally advanced head and neck oropharyngeal cancer with bilateral lymph node coverage, and 1 with a nonmobile lung cancer. Plan quality, robustness, and total estimated delivery time were compared with the robust optimized multifield step-and-shoot arc plan without SPArc optimization (Arc{sub multi-field}) and the standard robust optimized intensity modulatedmore » proton therapy (IMPT) plan. Dose-volume histograms of target and organs at risk were analyzed, taking into account the setup and range uncertainties. Total delivery time was calculated on the basis of a 360° gantry room with 1 revolutions per minute gantry rotation speed, 2-millisecond spot switching time, 1-nA beam current, 0.01 minimum spot monitor unit, and energy layer switching time of 0.5 to 4 seconds. Results: The SPArc plan showed potential dosimetric advantages for both clinical sample cases. Compared with IMPT, SPArc delivered 8% and 14% less integral dose for oropharyngeal and lung cancer cases, respectively. Furthermore, evaluating the lung cancer plan compared with IMPT, it was evident that the maximum skin dose, the mean lung dose, and the maximum dose to ribs were reduced by 60%, 15%, and 35%, respectively, whereas the conformity index was improved from 7.6 (IMPT) to 4.0 (SPArc). The total treatment delivery time for lung and oropharyngeal cancer patients was reduced by 55% to 60% and 56% to 67%, respectively, when compared with Arc{sub multi-field} plans. Conclusion: The SPArc plan is the first robust and delivery-efficient proton spot-scanning arc therapy technique, which could potentially be implemented into routine clinical practice.« less

Comparative dosimetry study of three UK centres implementing total skin electron treatment through external audit.

PubMed

Misson-Yates, S; Gonzalez, R; McGovern, M; Greener, A

2015-05-01

This article describes the external audit measurements conducted in two UK centres implementing total skin electron beam therapy (TSEBT) and the results obtained. Measurements of output, energy, beam flatness and symmetry at a standard distance (95 or 100 cm SSD) were performed using a parallel plate chamber in solid water. Similarly, output and energy measurements were also performed at the treatment plane for single and dual fields. Clinical simulations were carried out using thermoluminescent dosemeters (TLDs) and Gafchromic® film (International Specialty Products, Wayne, NJ) on an anthropomorphic phantom. Extended distance measurements confirmed that local values for the beam dosimetry at Centres A and B were within 2% for outputs and 1-mm agreement of the expected depth at which the dose is 50% of the maximum for the depth-dose curve in water (R50,D) value. Clinical simulation using TLDs) showed an agreement of -1.6% and -6.7% compared with the expected mean trunk dose for each centre, respectively, and a variation within 10% (±1 standard deviation) across the trunk. The film results confirmed that the delivery of the treatment technique at each audited centre complies with the European Organisation for Research and Treatment of Cancer recommendations. This audit methodology has proven to be a successful way to confirm the agreement of dosimetric parameters for TSEBT treatments at both audited centres and could serve as the basis for an audit template to be used by other audit groups. TSEBT audits are not established in the UK owing to a limited number of centres carrying out the treatment technique. This article describes the audits performed at two UK centres prior to their clinical implementation.

Comparative dosimetry study of three UK centres implementing total skin electron treatment through external audit

PubMed Central

Gonzalez, R; McGovern, M; Greener, A

2015-01-01

Objective: This article describes the external audit measurements conducted in two UK centres implementing total skin electron beam therapy (TSEBT) and the results obtained. Methods: Measurements of output, energy, beam flatness and symmetry at a standard distance (95 or 100 cm SSD) were performed using a parallel plate chamber in solid water. Similarly, output and energy measurements were also performed at the treatment plane for single and dual fields. Clinical simulations were carried out using thermoluminescent dosemeters (TLDs) and Gafchromic® film (International Specialty Products, Wayne, NJ) on an anthropomorphic phantom. Results: Extended distance measurements confirmed that local values for the beam dosimetry at Centres A and B were within 2% for outputs and 1-mm agreement of the expected depth at which the dose is 50% of the maximum for the depth–dose curve in water (R50,D) value. Clinical simulation using TLDs) showed an agreement of −1.6% and −6.7% compared with the expected mean trunk dose for each centre, respectively, and a variation within 10% (±1 standard deviation) across the trunk. The film results confirmed that the delivery of the treatment technique at each audited centre complies with the European Organisation for Research and Treatment of Cancer recommendations. Conclusion: This audit methodology has proven to be a successful way to confirm the agreement of dosimetric parameters for TSEBT treatments at both audited centres and could serve as the basis for an audit template to be used by other audit groups. Advances in knowledge: TSEBT audits are not established in the UK owing to a limited number of centres carrying out the treatment technique. This article describes the audits performed at two UK centres prior to their clinical implementation. PMID:25761213

Nanoparticle exposure in animals can be visualized in the skin and analysed via skin biopsy

NASA Astrophysics Data System (ADS)

Sykes, Edward A.; Dai, Qin; Tsoi, Kim M.; Hwang, David M.; Chan, Warren C. W.

2014-05-01

The increasing use of nanomaterials raises concerns about the long-term effects of chronic nanoparticle exposure on human health. However, nanoparticle exposure is difficult to evaluate non-invasively using current measurement techniques. Here we show that the skin is an important site of nanoparticle accumulation following systemic administration. Mice injected with high doses of gold nanoparticles have visibly blue skin while quantum dot-treated animals fluoresce under ultraviolet excitation. More importantly, elemental analysis of excised skin correlates with the injected dose and nanoparticle accumulation in the liver and spleen. We propose that skin analysis may be a simple strategy to quantify systemic nanoparticle exposure and predict nanoparticle fate in vivo. Our results suggest that in the future, dermal accumulation may also be exploited to trigger the release of ultraviolet and visible light-sensitive therapeutics that are currently impractical in vivo due to limits in optical penetration of tissues at these wavelengths.

A Web-based Tool to Aid the Identification of Chemicals Potentially Posing a Health Risk through Percutaneous Exposure.

PubMed

Gorman Ng, Melanie; Milon, Antoine; Vernez, David; Lavoué, Jérôme

2016-04-01

Occupational hygiene practitioners typically assess the risk posed by occupational exposure by comparing exposure measurements to regulatory occupational exposure limits (OELs). In most jurisdictions, OELs are only available for exposure by the inhalation pathway. Skin notations are used to indicate substances for which dermal exposure may lead to health effects. However, these notations are either present or absent and provide no indication of acceptable levels of exposure. Furthermore, the methodology and framework for assigning skin notation differ widely across jurisdictions resulting in inconsistencies in the substances that carry notations. The UPERCUT tool was developed in response to these limitations. It helps occupational health stakeholders to assess the hazard associated with dermal exposure to chemicals. UPERCUT integrates dermal quantitative structure-activity relationships (QSARs) and toxicological data to provide users with a skin hazard index called the dermal hazard ratio (DHR) for the substance and scenario of interest. The DHR is the ratio between the estimated 'received' dose and the 'acceptable' dose. The 'received' dose is estimated using physico-chemical data and information on the exposure scenario provided by the user (body parts exposure and exposure duration), and the 'acceptable' dose is estimated using inhalation OELs and toxicological data. The uncertainty surrounding the DHR is estimated with Monte Carlo simulation. Additional information on the selected substances includes intrinsic skin permeation potential of the substance and the existence of skin notations. UPERCUT is the only available tool that estimates the absorbed dose and compares this to an acceptable dose. In the absence of dermal OELs it provides a systematic and simple approach for screening dermal exposure scenarios for 1686 substances. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

THE SUSCEPTIBILITY OF CHICK EMBRYO SKIN ORGAN CULTURES TO INFLUENZA VIRUS FOLLOWING EXCESS VITAMIN A

PubMed Central

Huang, J. S.; Bang, F. B.

1964-01-01

The conversion of chick embryonic epidermis to mucous epithelium by excess vitamin A in organ culture as reported by Fell and Mellanby (5) was shown to be accompanied by a corresponding change of susceptibility to influenza and vaccinia viruses. Untreated epidermis of 10- to 12-day chick embryos supported the growth of influenza (PR8) virus in organ cultures and a maximum infectivity (EID50) titer was reached 2 to 3 days after infection. At the same time) the epidermis showed squamous keratinization, beginning about the 4th day of cultivation. Addition of excess vitamin A (40 µg per ml) to the skin organ culture induced the following changes: (a) mucous metaplasia of the epidermis which was usually first evident after 4 to 5 days in the vitamin A medium, (b) increase in the daily and maximum yield of influenza virus, if the epidermis had been grown for 4 or more days in the vitamin A medium before infection took place, and (c) decrease in the production of vaccinia virus under similar conditions. The maximum yield of both viruses remained unchanged, however, if excess vitamin A was introduced to the organ culture at the time of virus inoculation. The magnitude of increase in the yield of influenza virus in this organ culture system was found to be proportionally related to the concentration of vitamin A added 4 or more days before inoculation of this virus. Increasing doses of vitamin A however, had no effect on the short-term growth of influenza virus in tissue cultures of chorio-allantoic membrane. Observation on the early period (2 to 12 hours) of influenza virus growth initiated in the 4-day organ cultures of chick embryonic skin showed no significant difference in virus production between the normal and the vitamin A medium groups. The change of virus specificity apparently is not due to the presence of excess vitamin A per se, but appears to be related to the change of differentiation produced in the organ culture system. PMID:14206436

Risk assessment of excess drug and sunscreen absorption via skin with ablative fractional laser resurfacing : optimization of the applied dose for postoperative care.

PubMed

Chen, Wei-Yu; Fang, Chia-Lang; Al-Suwayeh, Saleh A; Yang, Hung-Hsu; Li, Yi-Ching; Fang, Jia-You

2013-09-01

The ablative fractional laser is a new modality used for surgical resurfacing. It is expected that laser treatment can generally deliver drugs into and across the skin, which is toxicologically relevant. The aim of this study was to establish skin absorption characteristics of antibiotics, sunscreens, and macromolecules via laser-treated skin and during postoperative periods. Nude mice were employed as the animal model. The skin received a single irradiation of a fractional CO2 laser, using fluences of 4-10 mJ with spot densities of 100-400 spots/cm(2). In vitro skin permeation using Franz cells was performed. Levels of skin water loss and erythema were evaluated, and histological examinations with staining by hematoxylin and eosin, cyclooxygenase-2, and claudin-1 were carried out. Significant signs of erythema, edema, and scaling of the skin treated with the fractional laser were evident. Inflammatory infiltration and a reduction in tight junctions were also observed. Laser treatment at 6 mJ increased tetracycline and tretinoin fluxes by 70- and 9-fold, respectively. A higher fluence resulted in a greater tetracycline flux, but lower skin deposition. On the other hand, tretinoin skin deposition increased following an increase in the laser fluence. The fractional laser exhibited a negligible effect on modulating oxybenzone absorption. Dextrans with molecular weights of 4 and 10 kDa showed increased fluxes from 0.05 to 11.05 and 38.54 μg/cm(2)/h, respectively. The optimized drug dose for skin treated with the fractional laser was 1/70-1/60 of the regular dose. The skin histology and drug absorption had recovered to a normal status within 2-3 days. Our findings provide the first report on risk assessment of excessive skin absorption after fractional laser resurfacing.

An electric field induced in the retina and brain at threshold magnetic flux density causing magnetophosphenes.

PubMed

Hirata, Akimasa; Takano, Yukinori; Fujiwara, Osamu; Dovan, Thanh; Kavet, Robert

2011-07-07

For magnetic field exposures at extremely low frequencies, the electrostimulatory response with the lowest threshold is the magnetophosphene, a response that corresponds to an adult exposed to a 20 Hz magnetic field of nominally 8.14 mT. In the IEEE standard C95.6 (2002), the corresponding in situ field in the retinal locus of an adult-sized ellipsoidal was calculated to be 53 mV m(-1). However, the associated dose in the retina and brain at a high level of resolution in anatomically correct human models is incompletely characterized. Furthermore, the dose maxima in tissue computed with voxel human models are prone to staircasing errors, particularly for the low-frequency dosimetry. In the analyses presented in this paper, analytical and quasi-static finite-difference time-domain (FDTD) solutions were first compared for a three-layer sphere exposed to a uniform 50 Hz magnetic field. Staircasing errors in the FDTD results were observed at the tissue interface, and were greatest at the skin-air boundary. The 99th percentile value was within 3% of the analytic maximum, depending on model resolution, and thus may be considered a close approximation of the analytic maximum. For the adult anatomical model, TARO, exposed to a uniform magnetic field, the differences in the 99th percentile value of in situ electric fields for 2 mm and 1 mm voxel models were at most several per cent. For various human models exposed at the magnetophosphene threshold at three orthogonal field orientations, the in situ electric field in the brain was between 10% and 70% greater than the analytical IEEE threshold of 53 mV m(-1), and in the retina was lower by roughly 50% for two horizontal orientations (anterior-posterior and lateral), and greater by about 15% for a vertically oriented field. Considering a reduction factor or safety factors of several folds applied to electrostimulatory thresholds, the 99th percentile dose to a tissue calculated with voxel human models may be used as an estimate of the tissue's maximum dose.

The pituitary-skin connection in amphibians. Reciprocal regulation of melanotrope cells and dermal melanocytes.

PubMed

Vaudry, H; Chartrel, N; Desrues, L; Galas, L; Kikuyama, S; Mor, A; Nicolas, P; Tonon, M C

1999-10-20

In amphibians, alpha-MSH secreted by the pars intermedia of the pituitary plays a pivotal role in the process of skin color adaptation. Reciprocally, the skin of amphibians contains a number of regulatory peptides, some of which have been found to regulate the activity of pituitary melanotrope cells. In particular, the skin of certain species of amphibians harbours considerable amounts of thyrotropin-releasing hormone, a highly potent stimulator of alpha-MSH release. Recently, we have isolated and sequenced from the skin of the frog Phyllomedusa bicolor--a novel peptide named skin peptide tyrosine tyrosine (SPYY), which exhibits 94% similarity with PYY from the frog Rana ridibunda. For concentrations ranging from 5 x 10(-10) to 10(-7) M, SPYY induces a dose-related inhibition of alpha-MSH secretion. At a dose of 10(-7) M, SPYY totally abolished alpha-MSH release. These data strongly suggest the existence of a regulatory loop between the pars intermedia of the pituitary and the skin in amphibians.

Tumorigenic action of beta, proton, alpha and electron radiation on the rat skin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burns, F.J.

1980-01-01

Rat skin is utilized as a model system for studying dose and time related aspects of the oncogenic action of ionizing radiation, ultraviolet light and polycyclic aromatic hydrocarbons. Molecular lesions in the DNA of the epidermis, including strand breaks and thymine dimers, are measured and compared to the temporal and dose related aspects of tumor induction. The induction and repair kinetics of molecular lesions are compared to split dose recovery as modified by sensitizers and type of radition of oncogenic damage.

Characterization of a MOSkin detector for in vivo skin dose measurements during interventional radiology procedures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Safari, M. J.; Wong, J. H. D.; Ng, K. H., E-mail: ngkh@um.edu.my

2015-05-15

Purpose: The MOSkin is a MOSFET detector designed especially for skin dose measurements. This detector has been characterized for various factors affecting its response for megavoltage photon beams and has been used for patient dose measurements during radiotherapy procedures. However, the characteristics of this detector in kilovoltage photon beams and low dose ranges have not been studied. The purpose of this study was to characterize the MOSkin detector to determine its suitability for in vivo entrance skin dose measurements during interventional radiology procedures. Methods: The calibration and reproducibility of the MOSkin detector and its dependency on different radiation beam qualitiesmore » were carried out using RQR standard radiation qualities in free-in-air geometry. Studies of the other characterization parameters, such as the dose linearity and dependency on exposure angle, field size, frame rate, depth-dose, and source-to-surface distance (SSD), were carried out using a solid water phantom under a clinical x-ray unit. Results: The MOSkin detector showed good reproducibility (94%) and dose linearity (99%) for the dose range of 2 to 213 cGy. The sensitivity did not significantly change with the variation of SSD (±1%), field size (±1%), frame rate (±3%), or beam energy (±5%). The detector angular dependence was within ±5% over 360° and the dose recorded by the MOSkin detector in different depths of a solid water phantom was in good agreement with the Markus parallel plate ionization chamber to within ±3%. Conclusions: The MOSkin detector proved to be reliable when exposed to different field sizes, SSDs, depths in solid water, dose rates, frame rates, and radiation incident angles within a clinical x-ray beam. The MOSkin detector with water equivalent depth equal to 0.07 mm is a suitable detector for in vivo skin dosimetry during interventional radiology procedures.« less

Characterization of a MOSkin detector for in vivo skin dose measurements during interventional radiology procedures.

PubMed

Safari, M J; Wong, J H D; Ng, K H; Jong, W L; Cutajar, D L; Rosenfeld, A B

2015-05-01

The MOSkin is a MOSFET detector designed especially for skin dose measurements. This detector has been characterized for various factors affecting its response for megavoltage photon beams and has been used for patient dose measurements during radiotherapy procedures. However, the characteristics of this detector in kilovoltage photon beams and low dose ranges have not been studied. The purpose of this study was to characterize the MOSkin detector to determine its suitability for in vivo entrance skin dose measurements during interventional radiology procedures. The calibration and reproducibility of the MOSkin detector and its dependency on different radiation beam qualities were carried out using RQR standard radiation qualities in free-in-air geometry. Studies of the other characterization parameters, such as the dose linearity and dependency on exposure angle, field size, frame rate, depth-dose, and source-to-surface distance (SSD), were carried out using a solid water phantom under a clinical x-ray unit. The MOSkin detector showed good reproducibility (94%) and dose linearity (99%) for the dose range of 2 to 213 cGy. The sensitivity did not significantly change with the variation of SSD (± 1%), field size (± 1%), frame rate (± 3%), or beam energy (± 5%). The detector angular dependence was within ± 5% over 360° and the dose recorded by the MOSkin detector in different depths of a solid water phantom was in good agreement with the Markus parallel plate ionization chamber to within ± 3%. The MOSkin detector proved to be reliable when exposed to different field sizes, SSDs, depths in solid water, dose rates, frame rates, and radiation incident angles within a clinical x-ray beam. The MOSkin detector with water equivalent depth equal to 0.07 mm is a suitable detector for in vivo skin dosimetry during interventional radiology procedures.

First application of dynamic infrared imaging in boron neutron capture therapy for cutaneous malignant melanoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Santa Cruz, G. A.; Gonzalez, S. J.; Bertotti, J.

2009-10-15

Purpose: The purpose of this study is to assess the potential of dynamic infrared imaging (DIRI) as a functional, noninvasive technique for evaluating the skin acute toxicity and tumor control within the framework of the Argentine boron neutron capture therapy (BNCT) program for cutaneous malignant melanoma. Methods: Two patients enrolled in the Argentine phase I/II BNCT clinical trial for cutaneous malignant melanoma were studied with DIRI. An uncooled infrared camera, providing a video output signal, was employed to register the temperature evolution of the normal skin and tumor regions in patients subjected to a mild local cooling (cold stimulus). Inmore » order to study the spatial correlation between dose and acute skin reactions, three-dimensional representations of the superficial dose delivered to skin were constructed and cameralike projections of the dose distribution were coregistered with visible and infrared images. Results: The main erythematous reaction was observed clinically between the second and fifth week post-BNCT. Concurrently, with its clinical onset, a reactive increase above the basal skin temperature was observed with DIRI in the third week post-BNCT within regions that received therapeutic doses. Melanoma nodules appeared as highly localized hyperthermic regions. 2 min after stimulus, these regions reached a temperature plateau and increased in size. Temperature differences with respect to normal skin up to 10 deg. C were observed in the larger nodules. Conclusions: Preliminary results suggest that DIRI, enhanced by the application of cold stimuli, may provide useful functional information associated with the metabolism and vasculature of tumors and inflammatory processes related to radiation-induced changes in the skin as well. These capabilities are aimed at complementing the clinical observations and standard imaging techniques, such as CT and Doppler ultrasound.« less

Chronic health effects in people exposed to arsenic via the drinking water: dose-response relationships in review.

PubMed

Yoshida, Takahiko; Yamauchi, Hiroshi; Fan Sun, Gui

2004-08-01

Chronic arsenic (As) poisoning has become a worldwide public health issue. Most human As exposure occurs from consumption of drinking water containing high amounts of inorganic As (iAs). In this paper, epidemiological studies conducted on the dose-response relationships between iAs exposure via the drinking water and related adverse health effects are reviewed. Before the review, the methods for evaluation of the individual As exposure are summarized and classified into two types, that is, the methods depending on As concentration of the drinking water and the methods depending on biological monitoring for As exposure; certain methods may be applied as optimum As exposure indexes to study dose-response relationship based on various As exposure situation. Chronic effects of iAs exposure via drinking water include skin lesions, neurological effects, hypertension, peripheral vascular disease, cardiovascular disease, respiratory disease, diabetes mellitus, and malignancies including skin cancer. The skin is quite sensitive to arsenic, and skin lesions are some of the most common and earliest nonmalignant effects related to chronic As exposure. The increase of prevalence in the skin lesions has been observed even at the exposure levels in the range of 0.005-0.01 mg/l As in drinking waters. Skin, lung, bladder, kidney, liver, and uterus are considered as sites As-induced malignancies, and the skin is though to be perhaps the most sensitive site. Prospective studies in large area of endemic As poisoning, like Bangladesh or China, where the rate of malignancies is expected to increase within the next several decades, will help to clarify the dose-response relationship between As exposure levels and adverse health effects with enhanced accuracy.

The effects of hedonically acceptable red pepper doses on thermogenesis and appetite

PubMed Central

Ludy, Mary-Jon; Mattes, Richard D.

2010-01-01

Previous studies suggest consumption of red pepper (RP) promotes negative energy balance. However, the RP dose provided in these studies (up to 10 g/meal) usually exceeded the amount preferred by the general population in the United States (mean = ~ 1 g/meal). The objective of this study was to evaluate the effects of hedonically acceptable RP doses served at a single meal in healthy, lean individuals on thermogenesis and appetite. Twenty-five men and women (aged 23.0 ± 0.5 y, BMI 22.6 ± 0.3 kg/m2, 13 spicy food users and 12 non-users) participated in a randomized crossover trial during which they consumed a standardized quantity (1 g); their preferred quantity (regular spicy foods users 1.8 ± 0.3 g/meal, non-users 0.3 ± 0.1 g/meal); or no RP. Energy expenditure, core body and skin temperature, and appetite were measured. Postprandial energy expenditure and core body temperature were greater, and skin temperature was lower, after test loads with 1 g RP than no RP. Respiratory quotient was lower after the preferred RP dose was ingested orally, compared to in capsule form. These findings suggest that RP’s effects on energy balance stem from a combination of metabolic and sensory inputs, and that oral exposure is necessary to achieve RP’s maximum benefits. Energy intake was lower after test loads with 1 g RP than no RP in non-users, but not in users. Preoccupation with food, and the desire to consume fatty, salty, and sweet foods were decreased more (or tended to be decreased more) in non-users than users after a 1 g RP test load, but did not vary after a test load with no RP. This suggests that individuals may become desensitized to the effects of RP with long-term spicy food intake. PMID:21093467

Oral desensitization to milk: how to choose the starting dose!

PubMed Central

Mori, Francesca; Pucci, Neri; Rossi, Maria Elisabetta; de Martino, Maurizio; Azzari, Chiara; Novembre, Elio

2010-01-01

Mori F, Pucci N, Rossi ME, de Martino M, Azzari C, Novembre E. Oral desensitization to milk: how to choose the starting dose! Pediatr Allergy Immunol 2010: 21: e450–e453. © 2009 John Wiley & Sons A/S A renewed interest in oral desensitization as treatment for food allergy has been observed in the last few years. We studied a novel method based on the end point skin prick test procedure to establish the starting dose for oral desensitization in a group of 30 children higly allergic to milk. The results (in terms of reactions to the first dose administered) were compared with a group of 20 children allergic to milk as well. Such control group started to swallow the same dose of 0.015 mg/ml of milk. None reacted to the first dose when administered according to the end point skin prick test. On the other side, ten out of 20 children (50%) from the control group showed mild allergic reactions to the first dose of milk. In conclusion the end point skin prick test procedure results safe and easy to be performed in each single child in order to find out the starting dose for oral desensitization to milk, also by taking into account the individual variability. PMID:19624618

In vivo percutaneous absorption of boric acid, borax, and disodium octaborate tetrahydrate in humans compared to in vitro absorption in human skin from infinite and finite doses.

PubMed

Wester, R C; Hui, X; Hartway, T; Maibach, H I; Bell, K; Schell, M J; Northington, D J; Strong, P; Culver, B D

1998-09-01

Literature from the first half of this century report concern for toxicity from topical use of boric acid, but assessment of percutaneous absorption has been impaired by lack of analytical sensitivity. Analytical methods in this study included inductively coupled plasma-mass spectrometry which now allows quantitation of percutaneous absorption of 10B in 10B-enriched boric acid, borax, and disodium octaborate tetrahydrate (DOT) in biological matrices. This made it possible, in the presence of comparatively large natural dietary boron intakes for the in vivo segment of this study, to quantify the boron passing through skin. Human volunteers were dosed with 10B-enriched boric acid, 5.0%, borax, 5.0%, or disodium octaborate tetrahydrate, 10%, in aqueous solutions. Urinalysis, for boron and changes in boron isotope ratios, was used to measure absorption. Boric acid in vivo percutaneous absorption was 0.226 (SD = 0.125) mean percentage dose, with flux and permeability constant (Kp) calculated at 0.009 microgram/cm2/h and 1.9 x 10(-7) cm/h, respectively. Borax absorption was 0.210 (SD = 0.194) mean percentage of dose, with flux and Kp calculated at 0.009 microgram/cm2/h and 1.8 x 10(-7) cm/h, respectively. DOT absorption was 0.122 (SD = 0.108) mean percentage, with flux and Kp calculated at 0.01 microgram/cm2/h and 1.0 x 10(-7) cm/h, respectively. Pretreatment with the potential skin irritant 2% sodium lauryl sulfate had no effect on boron skin absorption. In vitro human skin percentage of doses of boric acid absorbed were 1.2 for a 0.05% solution, 0.28 for a 0.5% solution, and 0.70 for a 5.0% solution. These absorption amounts translated into flux values of, respectively, 0.25, 0.58, and 14.58 micrograms/cm2/h and permeability constants (Kp) of 5.0 x 10(-4), 1.2 x 10(-4), and 2.9 x 10(-4) cm/h for the 0.05, 0.5, and 5.0% solutions. The above in vitro doses were at infinite, 1000 microliters/cm2 volume. At 2 microliters/cm2 (the in vivo dosing volume), flux decreased some 200-fold to 0.07 microgram/cm2/h and Kp of 1.4 x 10(-6) cm/h, while percentage of dose absorbed was 1.75%. Borax dosed at 5.0%/1000 microliters/cm2 had 0.41% dose absorbed, flux at 8.5 micrograms/cm2/h, and Kp was 1.7 x 10(-4) cm/h. Disodium octaborate tetrahydrate (DOT) dosed at 10%/1000 microliters/cm2 was 0.19% dose absorbed, flux at 7.9 micrograms/cm2/h, and Kp was 0.8 x 10(-4) cm/h. These in vitro results from infinite doses (1000 microliters/cm2) were 1000-fold greater than those obtained in the companion in vivo study. The results from the finite (2 microliters/cm2) dosing were closer (10-fold difference) to the in vivo results. General application of infinite dose percutaneous absorption values for risk assessment is questioned by these results. These in vivo results show that percutaneous absorption of boron, as boric acid, borax, and disodium octaborate tetrahydrate, through intact human skin, is low and is significantly less than the average daily dietary intake. This very low boron skin absorption makes it apparent that, for the borates tested, the use of gloves to prevent systemic uptake is unnecessary. These findings do not apply to abraded or otherwise damaged skin.

The role of natural and UV-induced skin pigmentation on low-fluence IPL-induced side effects: a randomized controlled trial.

PubMed

Thaysen-Petersen, Daniel; Lin, Jennifer Y; Nash, Jf; Beerwerth, Frank; Wulf, Hans C; Philipsen, Peter A; Haedersdal, Merete

2014-02-01

The risk of adverse skin effects following light-based hair removal is greater in pigmented skin based on the theory of selective photothermolysis. Thus sunlight-induced pigment i.e., facultative pigmentation, increases the risk of adverse skin effects, perhaps disproportionately. The aim of this study was to evaluate the influence of constitutive and facultative skin pigmentation on low-fluence intense pulsed light (IPL)-induced adverse skin effects. Twenty-one subjects with Fitzpatrick skin type II-IV were enrolled. Two buttock blocks were randomized to receive 0 or 8 solar simulated ultraviolet radiation (UVR) exposures of consecutively increasing Standard Erythema Doses (2-4 SED). Each block was subdivided into four sites, randomized to receive IPL of 0, 7, 8, or 10 J/cm(2) , once a week for 3 weeks. Biopsies were taken 16-24 hours after the first IPL exposure and subjects were seen 1 and 4 weeks after the last IPL exposure. Outcome measures were: (i) skin reactions, (ii) pain, (iii) mRNA expression of pigment-markers microphthalmia-associated transcription factor (MITF) and pro-opiomelanocortin (POMC), and (iv) clinical appearance of biopsy wounds. Skin pigmentation increased after UVR (baseline median 13.8%, after UVR 28.1%, P = 0.0001) in all skin types. Subjects reported low pain intensities (median 1.5, scale 0-10) and experienced transient erythema immediately after IPL exposure. No persistent erythema, blisters, crusting, textual, or pigment changes were observed. The risk of erythema and pain intensities increased with IPL dose and skin pigmentation (P < 0.03). There was no difference in pain or skin reactions in skin with similar degree of natural and facultative pigmentation (P ≥ 0.104). Expression of cellular pigment-markers was not influenced by IPL exposure, neither in constitutive nor in facultative pigmented skin. Clinical appearance of biopsy wounds was unaffected by IPL exposure. The prevalence and intensity of low-fluence IPL-induced adverse skin effects depended on IPL dose and skin pigmentation regardless of the origin, i.e., constitutive versus UV induced. © 2013 Wiley Periodicals, Inc.

Histamine response and local cooling in the human skin: involvement of H1- and H2-receptors.

PubMed

Grossmann, M; Jamieson, M J; Kirch, W

1999-08-01

Histamine may contribute locally to cutaneous blood flow control under normal and pathologic conditions. The objective of this study was to observe the influence of skin temperature on histamine vasodilation, and the roles of H1-and H2-receptors using novel noninvasive methods. Eleven healthy subjects received, double-blind, single doses of the H1-receptor antagonist cetirizine (10 mg), cetirizine (10 mg) plus the H2-receptor antagonist cimetidine (400 mg), or placebo on separate occasions. Histamine was dosed cumulatively by iontophoresis to the forearm skin at 34 degrees C and 14 degrees C. Laser-Doppler flux (LDF) was measured at the same sites using customised probeholder/iontophoretic chambers with Peltier cooling elements. Finger mean arterial pressure (MAP) was measured and cutaneous vascular conductance calculated as LDF/MAP. Histamine vasodilation was reduced in cold skin. Cetirizine shifted the histamine dose-response at both temperatures: statistically significantly at 14 degrees C only. Combined H1- and H2-receptor antagonism shifted the response significantly at both temperatures. H1- and H2-receptors mediate histamine-induced skin vasodilation. The sensitivity of these receptors, particularly the H1- receptor, is attenuated at low skin temperature. Whether the reduced effect in cold skin represents specific receptor or postreceptor desensitization, or nonspecific attenuation of cutaneous vasodilation remains to be elucidated.

Nanostructured lipid carriers-based flurbiprofen gel after topical administration: acute skin irritation, pharmacodynamics, and percutaneous absorption mechanism.

PubMed

Song, Aihua; Su, Zhen; Li, Sanming; Han, Fei

2015-01-01

In order to assess the preliminary safety and effectiveness of nanostructured lipid carriers-based flurbiprofen gel (FP NLC-gel), the acute irritation test, in vivo pharmacodynamics evaluation and pharmacokinetic study were investigated after topical application. No dropsy and erythema were observed after continuous dosing 7 d of FP NLC-gel on the rabbit skin, and the xylene-induced ear drossy could be inhibited by FP NLC-gel at different dosages. The maximum concentration of FP in rats muscle was 2.03 μg/g and 1.55 μg/g after oral and topical administration, respectively. While the peak concentration in untreated muscle after topical administration was only 0.37 μg/mL. And at any time, following topical administration the mean muscle-plasma concentration ratio Cmuscle/CPlasma was obviously higher than that following oral administration. Results indicated that FP could directly penetrate into the subcutaneous muscle tissue from the administration site. Thus, the developed FP NLC-gel could be a safe and effective vehicle for topical delivery of FP.

Time course of skin features and inflammatory biomarkers after liquid sulfur mustard exposure in SKH-1 hairless mice.

PubMed

Mouret, Stéphane; Wartelle, Julien; Batal, Mohamed; Emorine, Sandy; Bertoni, Marine; Poyot, Thomas; Cléry-Barraud, Cécile; Bakdouri, Nacera El; Peinnequin, André; Douki, Thierry; Boudry, Isabelle

2015-01-05

Sulfur mustard (SM) is a strong bifunctional alkylating agent that produces severe tissue injuries characterized by erythema, edema, subepidermal blisters and a delayed inflammatory response after cutaneous exposure. However, despite its long history, SM remains a threat because of the lack of effective medical countermeasures as the molecular mechanisms of these events remain unclear. This limited number of therapeutic options results in part of an absence of appropriate animal models. We propose here to use SKH-1 hairless mouse as the appropriate model for the design of therapeutic strategies against SM-induced skin toxicity. In the present study particular emphasis was placed on histopathological changes associated with inflammatory responses after topical exposure of dorsal skin to three different doses of SM (0.6, 6 and 60mg/kg) corresponding to a superficial, a second-degree and a third-degree burn. Firstly, clinical evaluation of SM-induced skin lesions using non invasive bioengineering methods showed that erythema and impairment of skin barrier increased in a dose-dependent manner. Histological evaluation of skin sections exposed to SM revealed that the time to onset and the severity of symptoms including disorganization of epidermal basal cells, number of pyknotic nuclei, activation of mast cells and neutrophils dermal invasion were dose-dependent. These histopathological changes were associated with a dose- and time-dependent increase in expression of specific mRNA for inflammatory mediators such as interleukins (IL1β and IL6), tumor necrosis factor (TNF)-α, cycloxygenase-2 (COX-2), macrophage inflammatory proteins (MIP-1α, MIP-2 and MIP-1αR) and keratinocyte chemoattractant (KC also called CXCL1) as well as adhesion molecules (L-selectin and vascular cell adhesion molecule (VCAM)) and growth factor (granulocyte colony-stimulating factor (Csf3)). A dose-dependent increase was also noted after SM exposure for mRNA of matrix metalloproteinases (MMP9) and laminin-γ2 which are associated with SM-induced blisters formation. Taken together, our results show that SM-induced skin histopathological changes related to inflammation is similar in SKH-1 hairless mice and humans. SKH-1 mouse is thus a reliable animal model for investigating the SM-induced skin toxicity and to develop efficient treatment against SM-induced inflammatory skin lesions. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Tissue interface pressure and skin integrity in critically ill, mechanically ventilated patients.

PubMed

Grap, Mary Jo; Munro, Cindy L; Wetzel, Paul A; Schubert, Christine M; Pepperl, Anathea; Burk, Ruth S; Lucas, Valentina

2017-02-01

To describe tissue interface pressure, time spent above critical pressure levels and the effect on skin integrity at seven anatomical locations. Descriptive, longitudinal study in critically ill mechanically ventilated adults, from Surgical Trauma ICU-STICU; Medical Respiratory ICU-MRICU; Neuroscience ICU-NSICU in a Mid-Atlantic urban university medical centre. Subjects were enroled in the study within 24hours of intubation. Tissue interface pressure was measured continuously using the XSENSOR pressure mapping system (XSENSOR Technology Corporation, Calgary, Canada). Skin integrity was observed at all sites, twice daily, using the National Pressure Ulcer Advisory Panel staging system, for the first seven ICU days and at day 10 and 14. Of the 132 subjects, 90.9% had no observed changes in skin integrity. Maximum interface pressure was above 32mmHg virtually 100% of the time for the sacrum, left and right trochanter. At the 45mmHg level, the left and right trochanter had the greatest amount of time above this level (greater than 95% of the time), followed by the sacrum, left and right scapula, and the left and right heels. Similarly, at levels above 60mmHg, the same site order applied. For those six subjects with sacral skin integrity changes, maximum pressures were greater than 32mmHg 100% of the time. Four of the six sacral changes were associated with greater amounts of time above both 45mmHg and 60mmHg than the entire sample. Maximum tissue interface pressure was above critical levels for the majority of the documented periods, especially in the sacrum, although few changes in skin integrity were documented. Time spent above critical levels for mean pressures were considerably less compared to maximum pressures. Maximum pressures may have reflected pressure spikes, but the large amount of time above the critical pressure levels remains substantial. Copyright © 2016 Elsevier Ltd. All rights reserved.

Tissue interface pressure and skin integrity in critically ill, mechanically ventilated patients☆

PubMed Central

Grap, Mary Jo; Munro, Cindy L.; Wetzel, Paul A.; Schubert, Christine M.; Pepperl, Anathea; Burk, Ruth S.; Lucas, Valentina

2016-01-01

Summary Objective To describe tissue interface pressure, time spent above critical pressure levels and the effect on skin integrity at seven anatomical locations. Design, setting, patients Descriptive, longitudinal study in critically ill mechanically ventilated adults, from Surgical Trauma ICU-STICU; Medical Respiratory ICU-MRICU; Neuroscience ICU-NSICU in a Mid-Atlantic urban university medical centre. Subjects were enroled in the study within 24 hours of intubation. Measurements Tissue interface pressure was measured continuously using the XSENSOR pressure mapping system (XSENSOR Technology Corporation, Calgary, Canada). Skin integrity was observed at all sites, twice daily, using the National Pressure Ulcer Advisory Panel staging system, for the first seven ICU days and at day 10 and 14. Results Of the 132 subjects, 90.9% had no observed changes in skin integrity. Maximum interface pressure was above 32 mmHg virtually 100% of the time for the sacrum, left and right trochanter. At the 45 mmHg level, the left and right trochanter had the greatest amount of time above this level (greater than 95% of the time), followed by the sacrum, left and right scapula, and the left and right heels. Similarly, at levels above 60 mmHg, the same site order applied. For those six subjects with sacral skin integrity changes, maximum pressures were greater than 32 mmHg100% of the time. Four of the six sacral changes were associated with greater amounts of time above both 45 mmHg and 60 mmHg than the entire sample. Conclusions Maximum tissue interface pressure was above critical levels for the majority of the documented periods, especially in the sacrum, although few changes in skin integrity were documented. Time spent above critical levels for mean pressures were considerably less compared to maximum pressures. Maximum pressures may have reflected pressure spikes, but the large amount of time above the critical pressure levels remains substantial. PMID:27836262

Model development and experimental validation for analyzing initial transients of irradiation of tissues during thermal therapy using short pulse lasers.

PubMed

Ganguly, Mohit; Miller, Stephanie; Mitra, Kunal

2015-11-01

Short pulse lasers with pulse durations in the range of nanoseconds and shorter are effective in the targeted delivery of heat energy for precise tissue heating and ablation. This photothermal therapy is useful where the removal of cancerous tissue sections is required. The objective of this paper is to use finite element modeling to demonstrate the differences in the thermal response of skin tissue to short-pulse and continuous wave laser irradiation in the initial stages of the irradiation. Models have been developed to validate the temperature distribution and heat affected zone during laser irradiation of excised rat skin samples and live anesthetized mouse tissue. Excised rat skin samples and live anesthetized mice were subjected to Nd:YAG pulsed laser (1,064 nm, 500 ns) irradiation of varying powers. A thermal camera was used to measure the rise in surface temperature as a result of the laser irradiation. Histological analyses of the heat affected zone created in the tissue samples due to the temperature rise were performed. The thermal interaction of the laser with the tissue was quantified by measuring the thermal dose delivered by the laser. Finite element geometries of three-dimensional tissue sections for continuum and vascular models were developed using COMSOL Multiphysics. Blood flow was incorporated into the vascular model to mimic the presence of discrete blood vessels and contrasted with the continuum model without blood perfusion. The temperature rises predicted by the continuum and the vascular models agreed with the temperature rises observed at the surface of the excised rat tissue samples and live anesthetized mice due to laser irradiation respectively. The vascular model developed was able to predict the cooling produced by the blood vessels in the region where the vessels were present. The temperature rise in the continuum model due to pulsed laser irradiation was higher than that due to continuous wave (CW) laser irradiation in the initial stages of the irradiation. The temperature rise due to pulsed and CW laser irradiation converged as the time of irradiation increased. A similar trend was observed when comparing the thermal dose for pulsed and CW laser irradiation in the vascular model. Finite element models (continuum and vascular) were developed that can be used to predict temperature rise and quantify the thermal dose resulting from laser irradiation of excised rat skin samples and live anesthetized mouse tissue. The vascular model incorporating blood perfusion effects predicted temperature rise better in the live animal tissue. The models developed demonstrated that pulsed lasers caused greater temperature rise and delivered a greater thermal dose than CW lasers of equal average power, especially during the initial transients of irradiation. This analysis will be beneficial for thermal therapy applications where maximum delivery of thermal dose over a short period of time is important. © 2015 Wiley Periodicals, Inc.

Comparison of 2D and 3D Imaging and Treatment Planning for Postoperative Vaginal Apex High-Dose Rate Brachytherapy for Endometrial Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russo, James K.; Armeson, Kent E.; Richardson, Susan, E-mail: srichardson@radonc.wustl.edu

2012-05-01

Purpose: To evaluate bladder and rectal doses using two-dimensional (2D) and 3D treatment planning for vaginal cuff high-dose rate (HDR) in endometrial cancer. Methods and Materials: Ninety-one consecutive patients treated between 2000 and 2007 were evaluated. Seventy-one and 20 patients underwent 2D and 3D planning, respectively. Each patient received six fractions prescribed at 0.5 cm to the superior 3 cm of the vagina. International Commission on Radiation Units and Measurements (ICRU) doses were calculated for 2D patients. Maximum and 2-cc doses were calculated for 3D patients. Organ doses were normalized to prescription dose. Results: Bladder maximum doses were 178% ofmore » ICRU doses (p < 0.0001). Two-cubic centimeter doses were no different than ICRU doses (p = 0.22). Two-cubic centimeter doses were 59% of maximum doses (p < 0.0001). Rectal maximum doses were 137% of ICRU doses (p < 0.0001). Two-cubic centimeter doses were 87% of ICRU doses (p < 0.0001). Two-cubic centimeter doses were 64% of maximum doses (p < 0.0001). Using the first 1, 2, 3, 4 or 5 fractions, we predicted the final bladder dose to within 10% for 44%, 59%, 83%, 82%, and 89% of patients by using the ICRU dose, and for 45%, 55%, 80%, 85%, and 85% of patients by using the maximum dose, and for 37%, 68%, 79%, 79%, and 84% of patients by using the 2-cc dose. Using the first 1, 2, 3, 4 or 5 fractions, we predicted the final rectal dose to within 10% for 100%, 100%, 100%, 100%, and 100% of patients by using the ICRU dose, and for 60%, 65%, 70%, 75%, and 75% of patients by using the maximum dose, and for 68%, 95%, 84%, 84%, and 84% of patients by using the 2-cc dose. Conclusions: Doses to organs at risk vary depending on the calculation method. In some cases, final dose accuracy appears to plateau after the third fraction, indicating that simulation and planning may not be necessary in all fractions. A clinically relevant level of accuracy should be determined and further research conducted to address this issue.« less

Cutaneous malignant melanoma incidences analyzed worldwide by sex, age, and skin type over personal Ultraviolet-B dose shows no role for sunburn but implies one for Vitamin D3

PubMed Central

Godar, Dianne E.; Subramanian, Madhan; Merrill, Stephen J.

2017-01-01

ABSTRACT Because the incidence of cutaneous malignant melanoma (CMM) was reported to increase with increasing terrestrial UVR (290–400 nm) doses in the US back in 1975 and a recent publication showed no association exists with UVR exposure at all, we set out to fully elucidate the role of UVR in CMM. To achieve this goal, we analyzed the CMM incidences over latitude and estimated the average personal UVR dose in the US and numerous countries (> 50) on 5 continents around the world. Using data from the International Agency for Research on Cancer in 2005, we performed worldwide analysis of CMM over UVR dose by sex, age group (0–14, 15–29, 30–49, 50–69, 70–85+) and Fitzpatrick skin types I-VI. Surprisingly, increasing UVR doses, which represent erythemally-weighted doses comprised primarily of UVB (290–315 nm) radiation, did not significantly correlate with increasing CMM incidence for people with any skin type anywhere in the world. Paradoxically, we found significant correlations between increasing CMM and decreasing UVB dose in Europeans with skin types I-IV. Both Europeans and Americans in some age groups have significant increasing CMM incidences with decreasing UVB dose, which shows UVB is not the main driver in CMM and suggests a possible role for lower cutaneous vitamin D3 levels and UVA (315–400 nm) radiation. CMM may be initiated or promoted by UVA radiation because people are exposed to it indoors through windows and outdoors through some sunscreen formulations. Thus, our findings may explain why some broad-spectrum sunscreen formulations do not protect against getting CMM. PMID:28924456

Role of levetiracetam in refractory seizures due to a rare progressive myoclonic epilepsy: Lafora body disease

PubMed Central

Hashmi, Mubashira; Saleem, Feroza; Mustafa, Muhammad Shahid; Sheerani, Mughis; Ehtesham, Zeeshan; Siddiqui, Khurram

2010-01-01

Lafora disease is one of the rare, most fatal progressive myoclonic epilepsies reported. We present a case of a teenager with intractable seizures and progressive mental decline, diagnosed as Lafora body disease on axillary skin biopsy. He was admitted with status epilepticus with refractory myoclonic and generalised tonic clonic seizures. Despite on maximum doses of multiple antiepileptic drugs and infusions of propofol and midazolam, his seizures were refractory to all forms of medical therapy tried. Levetiracetam (LEV), a pyrrolidine derivative, was introduced; he showed a prompt response and was weaned off successfully from infusions of anticonvulsants and mechanical ventilation within 48 h of introduction of LEV, followed by an almost seizure-free status. PMID:22791845

Skin dose mapping for non-uniform x-ray fields using a backscatter point spread function

NASA Astrophysics Data System (ADS)

Vijayan, Sarath; Xiong, Zhenyu; Shankar, Alok; Rudin, Stephen; Bednarek, Daniel R.

2017-03-01

Beam shaping devices like ROI attenuators and compensation filters modulate the intensity distribution of the xray beam incident on the patient. This results in a spatial variation of skin dose due to the variation of primary radiation and also a variation in backscattered radiation from the patient. To determine the backscatter component, backscatter point spread functions (PSF) are generated using EGS Monte-Carlo software. For this study, PSF's were determined by simulating a 1 mm beam incident on the lateral surface of an anthropomorphic head phantom and a 20 cm thick PMMA block phantom. The backscatter PSF's for the head phantom and PMMA phantom are curve fit with a Lorentzian function after being normalized to the primary dose intensity (PSFn). PSFn is convolved with the primary dose distribution to generate the scatter dose distribution, which is added to the primary to obtain the total dose distribution. The backscatter convolution technique is incorporated in the dose tracking system (DTS), which tracks skin dose during fluoroscopic procedures and provides a color map of the dose distribution on a 3D patient graphic model. A convolution technique is developed for the backscatter dose determination for the nonuniformly spaced graphic-model surface vertices. A Gafchromic film validation was performed for shaped x-ray beams generated with an ROI attenuator and with two compensation filters inserted into the field. The total dose distribution calculated by the backscatter convolution technique closely agreed with that measured with the film.

Skin Erythema, Pigmentation and Hydration Kinetics after Ultraviolet Radiation-induced Photodamage in Southern Chinese Women.

PubMed

Wan, Miaojian; Hu, Rong; Xie, Xiaoyuan; Gong, Zijian; Yi, Jinling; Chen, Haiyan; Xie, Lin; Guan, Xiaomin; Guan, Lei; Lai, Wei

2017-10-01

Although there have been some studies about changes of skin erythema and pigmentation following ultraviolet radiation in other races, the relevant data in Chinese have never been achieved. Thus, we evaluated the long-time course of skin erythema, pigmentation and hydration changes after different doses of solar-simulated ultraviolet (SSUV) irradiation in 26 Chinese women for 168 days. The erythema index increased abruptly and peaked during 3 days of SSUV exposure, then slowly returned to the baseline level starting at day 7 and completely recovered during 168-day course of this study only in one minimal erythema doses (MED) SSUV irradiation. The melanin index started to slowly increase at day 3 of SSUV exposure, peaking at day 14 and gradually returned to the baseline level thereafter, but did not return to the baseline level during 168-day course in all doses. Skin hydration slowly declined at day 3 of exposure, hitting the lowest point at day 7, then slowly recovered starting at day 14 and completely returned to the baseline level at day 28 only in 1.5MED. These results will serve as baseline data on Chinese skin and provide useful references for the treatment of serious skin photodamage in Chinese. © 2017 The American Society of Photobiology.

Mild skin photosensitivity in cancer patients following injection of Photochlor (2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a; HPPH) for photodynamic therapy.

PubMed

Bellnier, David A; Greco, William R; Nava, Hector; Loewen, Gregory M; Oseroff, Allan R; Dougherty, Thomas J

2006-01-01

To measure skin photosensitivity in cancer patients infused with the new second-generation photodynamic sensitizer Photochlor (2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a). A major disadvantage of using the clinically approved photosensitizer Photofrin is potentially prolonged and sometimes severe cutaneous phototoxicity. Forty-eight patients enrolled in Phases 1 and 2 clinical trials underwent two or more exposures to four graded doses (44.4, 66.6, 88.8 or 133.2 J/cm2) of artificial solar-spectrum light (SSL) before and after administration of Photochlor at a dose of 2.5, 3, 4, 5 or 6 mg/m2 . The most severe skin response, experienced by only six of the subjects, was limited to erythema without edema and could only be elicited by exposure to the highest light dose. Conversely, eight subjects had no discernible reaction to SSL at any light dose. For nearly all the patients, the peak skin response was obtained when the interval between sensitizer injection and exposure to SSL was 1 day and, generally, their sensitivity to SSL decreased with increasing sensitizer-light interval. For example, a 2-day sensitizer-SSL interval resulted in less severe reactions than those obtained with the 1-day interval in 79% of the subjects, while 90% of the subjects exposed to SSL 3 days after Photochlor infusion had responses that were less severe than those obtained with either the 1- or 2-day sensitizer-SSL interval. Photochlor, at clinically effective antitumor doses, causes only mild skin photosensitivity that declines rapidly over a few days.

Alterations in cell migration and cell viability of wounded human skin fibroblasts following visible red light exposure

NASA Astrophysics Data System (ADS)

Prabhu, Vijendra; Rao, Bola Sadashiva S.; Mahato, Krishna Kishore

2014-02-01

The present study intended to examine the effect of visible red light on structural and cellular parameters on wounded skin fibroblast cells. To achieve the stated objective, uniform scratch was created on confluent monolayered human skin fibroblast cells, and were exposed to single dose of He-Ne laser (15 mm spot, 6.6808 mWcm-2) at 1, 2, 3, 4, 5, 6 and 7 Jcm-2 in the presence and absence of 10% fetal bovine serum (FBS). Beam profile measurements of the expanded laser beam were conducted to ensure the beam uniformity. The influence of laser dose on the change in temperature was recorded using sensitive temperature probe. Additionally, following laser exposure cell migration and cell survival were documented at different time intervals on wounded human skin fibroblast cells grown in vitro. Beam profile measurements indicated more or less uniform power distribution over the whole beam area. Temperature monitoring of sham irradiated control and laser treatment groups displayed negligible temperature change indicating the absence of thermal effect at the tested laser doses. In the absence of 10% FBS, single exposure of different laser doses failed to produce any significant effects on cell migration or cell survival. However, in the presence of serum single exposure of 5 J/cm2 on wounded skin fibroblasts significantly enhanced the cell migration (P<0.05) compared to the other tested doses (1, 2, 3, 4, 6 and 7 J/cm2) and sham irradiated controls. In conclusion, the LLLT acts by improving cell migration and cell proliferation to produce measurable changes in wounded fibroblast cells.

WE-FG-202-01: Early Prediction of Radiotherapy Induced Skin Reactions Using Dynamic Infrared Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biswal, N; Cifter, G; Sun, J

Purpose: To predict radiotherapy induced skin reactions using dynamic infrared imaging. Methods: Thermal images were captured by our homebuilt system consisting of two flash lamps and an infrared (IR) camera. The surface temperature of the skin was first raised by ∼ 6 oC from ∼1 ms flashes. The camera then captured a series of IR images for 10 seconds. For each image, a baseline skin temperature was recorded for 0.5sec before heat impulse. The temporal temperature gradients were calculated between a reference point (immediately after the flash) and at a time point 9sec after that. Thermal effusivity, an intrinsic thermalmore » property of a material, was calculated from the surface temperature decay of skin. We present experimental data in five patients undergoing radiation therapy, of which 2 were Head & Neck, 1 was Sarcoma and 2 were Breast cancer patients. The prescribed doses were 45 – 60 Gy in 25 – 30 fractions. Each patient was imaged before treatment and after every fifth fraction until end of the treatment course. An area on the skin, outside the radiation field, was imaged as control region. During imaging, each patient’s irradiated skins were scored based on RTOG skin morbidity scoring criteria. Results: Temperature gradient, which is the temperature recovery rate, depends on the thermal properties of underlying tissue. It was observed that, the skin temperature and temporal temperature gradient increases with delivered radiation dose and skin RTOG score. The treatment does not change effusivity of superficial skin layer, however there was a significant difference in effusivity between treated and control areas at depth of ∼ 1.5 – 1.8 mm, increases with dose. Conclusion: The higher temporal temperature gradient and effusivity from irradiated areas suggest that there is more fluid under the irradiated skin, which causes faster temperature recovery. The mentioned effects may be predictors of Moist Desquamation.« less

SU-F-T-379: Dosimetric Impacts of Topical Agents and Dressings On Skin in Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tse, K; Morley, L; Cashell, A

Purpose: This study investigated the superficial dose enhancement in the application of topical agents, clinical materials (thermal mask and bolus) and dressings in megavoltage photon beam radiotherapy. Different topical skin agents, clinical materials and dressings were evaluated and compared for their skin dosimetric impacts on the patients during radiation treatment. Methods: Superficial dose enhancements, or percentage doses with and without the studying materials, were measured using the 6 MV (Field size = 10×10 cm{sup 2}) photon beams produced by a Varian TrueBeam linear accelerator. Twelve topical agents, five dressings (dry and wet conditions) and three clinical materials were studied. Amore » solid water phantom was used with a MOSFET dose detector (TN-1002RD, Thomson and Nielsen Electronic, Ottawa, Ontario, Canada) located under a 1-mm PMMA slab to measure the skin dose. The distance between the radiation source and phantom surface was set to 100 cm in all measurements. The topical agents were distributed evenly with 1.5 mm thickness using our specific sample holder on the phantom surface. Extrapolations were made of 0.5 mm thickness for the agents to provide meaningful clinical value. Results: By comparing surface doses without studying materials, it is found that no topical agents had superficial dose enhancement higher than the clinical materials namely, thermoplastic mask (128%), 5-mm Superflab™ bolus (158%) and 10-mm Superflab™ bolus (171%) regarding the same thickness. Superficial dose enhancement of dry dressing did not exceed 110.5%, while wet dressings produced higher dose enhancements (133% for wet Mepilex lite and 141% for wet Mepilex Ag transfer). Conclusion: It is concluded that the evaluated topical agents and dry dressings did not increase the superficial dose to a concerning level, even using excessive thickness in every fraction of radiation treatment. Wet dressings were found producing the bolus effect, but was still substantially less than applying a thin 5-mm bolus.« less

Dose optimization of total or partial skin electron irradiation by thermoluminescent dosimetry.

PubMed

Schüttrumpf, Lars; Neumaier, Klement; Maihoefer, Cornelius; Niyazi, Maximilian; Ganswindt, Ute; Li, Minglun; Lang, Peter; Reiner, Michael; Belka, Claus; Corradini, Stefanie

2018-05-01

Due to the complex surface of the human body, total or partial skin irradiation using large electron fields is challenging. The aim of the present study was to quantify the magnitude of dose optimization required after the application of standard fields. Total skin electron irradiation (TSEI) was applied using the Stanford technique with six dual-fields. Patients presenting with localized lesions were treated with partial skin electron irradiation (PSEI) using large electron fields, which were individually adapted. In order to verify and validate the dose distribution, in vivo dosimetry with thermoluminescent dosimeters (TLD) was performed during the first treatment fraction to detect potential dose heterogeneity and to allow for an individual dose optimization with adjustment of the monitor units (MU). Between 1984 and 2017, a total of 58 patients were treated: 31 patients received TSEI using 12 treatment fields, while 27 patients underwent PSEI and were treated with 4-8 treatment fields. After evaluation of the dosimetric results, an individual dose optimization was necessary in 21 patients. Of these, 7 patients received TSEI (7/31). Monitor units (MU) needed to be corrected by a mean value of 117 MU (±105, range 18-290) uniformly for all 12 treatment fields, corresponding to a mean relative change of 12% of the prescribed MU. In comparison, the other 14 patients received PSEI (14/27) and the mean adjustment of monitor units was 282 MU (±144, range 59-500) to single or multiple fields, corresponding to a mean relative change of 22% of the prescribed MU. A second dose optimization to obtain a satisfying dose at the prescription point was need in 5 patients. Thermoluminescent dosimetry allows an individual dose optimization in TSEI and PSEI to enable a reliable adjustment of the MUs to obtain the prescription dose. Especially in PSEI in vivo dosimetry is of fundamental importance.

Single dose pharmacokinetics, pharmacodynamics, tolerability and safety of BAY 60-5521, a potent inhibitor of cholesteryl ester transfer protein.

PubMed

Boettcher, Michael-Friedrich; Heinig, Roland; Schmeck, Carsten; Kohlsdorfer, Christian; Ludwig, Matthias; Schaefer, Anja; Gelfert-Peukert, Sabine; Wensing, Georg; Weber, Olaf

2012-02-01

To determine pharmacokinetics (PK), pharmacodynamics (PD), tolerability and safety of BAY 60-5521, a potent inhibitor of cholesteryl ester transfer protein (CETP). The first in man (FIM) study investigated the safety, tolerability, pharmacodynamics and pharmacokinetics in healthy male subjects following administration of single oral doses. The study was performed using a randomized, single-blind, placebo-controlled, single dose-escalation design. Thirty-eight young healthy male subjects (aged 20-45 years) received an oral dose of 5, 12.5, 25 or 50 mg BAY 60-5521 (n= 28) or were treated with a placebo (n= 10). In all four dose steps, only one adverse event (25 mg; mild skin rash) was considered drug related. Clinical laboratory parameters showed no clinically relevant changes. A clear dose-dependent CETP inhibition could be demonstrated starting at a dose of 5 mg. At a dose of 25 mg, a CETP inhibition >50% over 18 h was observed. After 50 mg, CETP inhibition >50% lasted more than 50 h. Twenty-four h after administration mean HDL-C-values showed a nearly dose-proportional increase. Following administration of 50 mg, a significant HDL-C increase of about 30% relative to baseline values was found. BAY 60-5521 was slowly absorbed reaching maximum concentrations in plasma after 4 to 6 h. The disposition in plasma was multi-exponential with an estimated mean terminal half-life of 76 to 144 h. BAY 60-5521 was clinically safe and well tolerated. No effects on heart rate, blood pressure and ECG recordings were observed during the study. A clear pharmacodynamic effect on CETP inhibition and HDL could be demonstrated. © 2011 The Authors. British Journal of Clinical Pharmacology © 2011 The British Pharmacological Society.

The biodisposition and hypertrichotic effects of bimatoprost in mouse skin

PubMed Central

Woodward, David F; Tang, Elaine S-H; Attar, Mayssa; Wang, Jenny W

2013-01-01

Studies on bimatoprost were performed with two objectives: (i) to determine whether bimatoprost possesses hair growth-stimulating properties beyond eyelash hypertrichosis and (ii) to investigate the biodisposition of bimatoprost in skin for the first time. Bimatoprost, at the dose used clinically for eyelash growth (0.03%) and given once daily for 14 days, increased pelage hair growth in C57/black 6 mice. This occurred as a much earlier onset of new hair growth in shaved mice and the time taken to achieve complete hair regrowth, according to photographic documentation and visual assessment. Bimatoprost biodisposition in the skin was determined at three concentrations: 0.01%, 0.03% and 0.06%. Dose-dependent Cmax values were obtained (3.41, 6.74, 12.3 μg/g tissue), and cutaneous bimatoprost was well maintained for 24 h following a single dose. Bimatoprost was recovered from the skin only as the intact molecule, with no detectable levels of metabolites. Thus, bimatoprost produces hypertrichosis as the intact molecule. PMID:23278986

On the importance of body posture and skin modelling with respect to in situ electric field strengths in magnetic field exposure scenarios

NASA Astrophysics Data System (ADS)

Schmid, Gernot; Hirtl, Rene

2016-06-01

The reference levels and maximum permissible exposure values for magnetic fields that are currently used have been derived from basic restrictions under the assumption of upright standing body models in a standard posture, i.e. with arms laterally down and without contact with metallic objects. Moreover, if anatomical modelling of the body was used at all, the skin was represented as a single homogeneous tissue layer. In the present paper we addressed the possible impacts of posture and skin modelling in scenarios of exposure to a 50 Hz uniform magnetic field on the in situ electric field strength in peripheral tissues, which must be limited in order to avoid peripheral nerve stimulation. We considered different body postures including situations where body parts form large induction loops (e.g. clasped hands) with skin-to-skin and skin-to-metal contact spots and compared the results obtained with a homogeneous single-layer skin model to results obtained with a more realistic two-layer skin representation consisting of a low-conductivity stratum corneum layer on top of a combined layer for the cellular epidermis and dermis. Our results clearly indicated that postures with loops formed of body parts may lead to substantially higher maximum values of induced in situ electric field strengths than in the case of standard postures due to a highly concentrated current density and in situ electric field strength in the skin-to-skin and skin-to-metal contact regions. With a homogeneous single-layer skin, as is used for even the most recent anatomical body models in exposure assessment, the in situ electric field strength may exceed the basic restrictions in such situations, even when the reference levels and maximum permissible exposure values are not exceeded. However, when using the more realistic two-layer skin model the obtained in situ electric field strengths were substantially lower and no violations of the basic restrictions occurred, which can be explained by the current-limiting effect of the low-conductivity stratum corneum layer.

Mometasone Furoate Effect on Acute Skin Toxicity in Breast Cancer Patients Receiving Radiotherapy: A Phase 3 Double-Blind, Randomized Trial from the North Central Cancer Treatment Group N06C4

PubMed Central

Miller, Robert C.; Schwartz, David J.; Sloan, Jeff A.; Griffin, Patricia C.; Deming, Richard L.; Anders, Jon C.; Stoffel, Thomas J.; Haselow, Robert E.; Schaefer, Paul L.; Bearden, James D.; Atherton, Pamela J.; Loprinzi, Charles L.; Martenson, James A.

2010-01-01

Purpose A 2-arm, double-blinded, randomized trial to evaluate the effect of 0.1% mometasone furoate (MMF) on acute skin-related toxicity in patients undergoing breast or chest wall radiotherapy. Methods and Materials Patients with ductal carcinoma in situ or invasive breast carcinoma receiving external beam radiotherapy to breast or chest wall were randomly assigned to daily apply 0.1% MMF or placebo cream. Primary study end point was provider-assessed maximum grade of Common Terminology Criteria for Adverse Events (CTCAE) version 3.0 radiation dermatitis. Secondary end points included provider-assessed CTCAE grade 3 or greater radiation dermatitis and adverse-event monitoring. Patient-reported outcome (PRO) measures included the Skindex-16, the Skin Toxicity Assessment Tool, a Symptom Experience Diary, and quality of life self-assessment. Assessment was performed at baseline, weekly during radiotherapy, and for 2 weeks after radiotherapy. Results In total, 176 patients were enrolled from September 21, 2007 through December 7, 2007. The provider-assessed primary end point showed no difference in mean maximum grade of radiation dermatitis by treatment arm (1.2 for MMF vs 1.3 for placebo; P=.18). CTCAE toxicity was greater in placebo group (P=.04), primarily from pruritus. For PRO measures, the maximum Skindex-16 score for MMF group showed less itching (P=.008), less irritation (P=.01), less symptom persistence or recurrence (P=.02), and less annoyance with skin problems (P=.04); the group's maximum Skin Toxicity Assessment Tool score showed less burning sensation (P=.02) and less itching (P=.002). Conclusion Patients receiving daily MMF during radiotherapy may experience reduced acute skin toxicity in comparison to placebo. PMID:20800381

Using the Ground Squirrel (Marmota bobak) as an Animal Model to Assess Monkeypox Drug Efficacy.

PubMed

Sergeev, A A; Kabanov, A S; Bulychev, L E; Sergeev, A A; Pyankov, O V; Bodnev, S A; Galahova, D O; Zamedyanskaya, A S; Titova, K A; Glotova, T I; Taranov, O S; Omigov, V V; Shishkina, L N; Agafonov, A P; Sergeev, A N

2017-02-01

In experiments to study the sensitivity of ground squirrels (Marmota bobak) to monkeypox virus (MPXV) at intranasal challenge, expressed pox-like clinical symptoms (hyperthermia, lymphadenitis, skin rash all over the body and mucous membranes and others) were observed 7-9 days post-infection. The 50% infective dose (ID 50 ) of MPXV for these marmots determined by the presence of clinical signs of the disease was 2.2 log 10 PFU. Some diseased marmots (about 40%) died 13-22 days post-infection, and the mortality rate was weakly dependent on MPXV infective dose. Lungs with trachea were primary target organs of marmots challenged intranasally (with ~30 ID 50 ). The pathogen got to secondary target organs of the animals mainly via the lymphatic way (with replication in bifurcation lymph nodes). Lungs with trachea, nasal mucosa and skin were the organs where the maximum MPXV amounts accumulated in these animals. Evidences of the pathogen presence and replication were revealed in these and subcutaneously infected marmots in the traditional primary target cells for MPXV (macrophages and respiratory tract epitheliocytes), as well as in some other cells (endotheliocytes, plasmocytes, fibroblasts, reticular and smooth muscle cells). Our use of this animal species to assess the antiviral efficacy of some drugs demonstrated the agreement of the obtained results with those described in scientific literature, which opens up the prospects of using marmots as animal models for monkeypox to develop therapeutic and preventive anti-smallpox drugs. © 2015 Blackwell Verlag GmbH.

10 CFR 835.702 - Individual monitoring records.

Code of Federal Regulations, 2010 CFR

2010-01-01

... emergency exposures. (b) Recording of the non-uniform equivalent dose to the skin is not required if the... internal dose (committed effective dose or committed equivalent dose) is not required for any monitoring...: (i) The effective dose from external sources of radiation (equivalent dose to the whole body may be...

10 CFR 835.702 - Individual monitoring records.

Code of Federal Regulations, 2011 CFR

2011-01-01

... emergency exposures. (b) Recording of the non-uniform equivalent dose to the skin is not required if the... internal dose (committed effective dose or committed equivalent dose) is not required for any monitoring...: (i) The effective dose from external sources of radiation (equivalent dose to the whole body may be...

10 CFR 835.702 - Individual monitoring records.

Code of Federal Regulations, 2014 CFR

2014-01-01

... emergency exposures. (b) Recording of the non-uniform equivalent dose to the skin is not required if the... internal dose (committed effective dose or committed equivalent dose) is not required for any monitoring...: (i) The effective dose from external sources of radiation (equivalent dose to the whole body may be...

10 CFR 835.702 - Individual monitoring records.

Code of Federal Regulations, 2013 CFR

2013-01-01

... emergency exposures. (b) Recording of the non-uniform equivalent dose to the skin is not required if the... internal dose (committed effective dose or committed equivalent dose) is not required for any monitoring...: (i) The effective dose from external sources of radiation (equivalent dose to the whole body may be...

10 CFR 835.702 - Individual monitoring records.

Code of Federal Regulations, 2012 CFR

2012-01-01

... emergency exposures. (b) Recording of the non-uniform equivalent dose to the skin is not required if the... internal dose (committed effective dose or committed equivalent dose) is not required for any monitoring...: (i) The effective dose from external sources of radiation (equivalent dose to the whole body may be...

Patient Dose During Carotid Artery Stenting With Embolic-Protection Devices: Evaluation With Radiochromic Films and Related Diagnostic Reference Levels According to Factors Influencing the Procedure

DOE Office of Scientific and Technical Information (OSTI.GOV)

D'Ercole, Loredana, E-mail: l.dercole@smatteo.pv.it; Quaretti, Pietro; Cionfoli, Nicola

2013-04-15

To measure the maximum entrance skin dose (MESD) on patients undergoing carotid artery stenting (CAS) using embolic-protection devices, to analyze the dependence of dose and exposure parameters on anatomical, clinical, and technical factors affecting the procedure complexity, to obtain some local diagnostic reference levels (DRLs), and to evaluate whether overcoming DRLs is related to procedure complexity. MESD were evaluated with radiochromic films in 31 patients (mean age 72 {+-} 7 years). Five of 33 (15 %) procedures used proximal EPD, and 28 of 33 (85 %) procedures used distal EPD. Local DRLs were derived from the recorded exposure parameters inmore » 93 patients (65 men and 28 women, mean age 73 {+-} 9 years) undergoing 96 CAS with proximal (33 %) or distal (67 %) EPD. Four bilateral lesions were included. MESD values (mean 0.96 {+-} 0.42 Gy) were <2 Gy without relevant dependence on procedure complexity. Local DRL values for kerma area product (KAP), fluoroscopy time (FT), and number of frames (N{sub FR}) were 269 Gy cm{sup 2}, 28 minutes, and 251, respectively. Only simultaneous bilateral treatment was associated with KAP (odds ratio [OR] 10.14, 95 % confidence interval [CI] 1-102.7, p < 0.05) and N{sub FR} overexposures (OR 10.8, 95 % CI 1.1-109.5, p < 0.05). Type I aortic arch decreased the risk of FT overexposure (OR 0.4, 95 % CI 0.1-0.9, p = 0.042), and stenosis {>=} 90 % increased the risk of N{sub FR} overexposure (OR 2.8, 95 % CI 1.1-7.4, p = 0.040). At multivariable analysis, stenosis {>=} 90 % (OR 2.8, 95 % CI 1.1-7.4, p = 0.040) and bilateral treatment (OR 10.8, 95 % CI 1.1-109.5, p = 0.027) were associated with overexposure for two or more parameters. Skin doses are not problematic in CAS with EPD because these procedures rarely lead to doses >2 Gy.« less

Fabrication of topical metered dose film forming sprays for pain management.

PubMed

Ranade, Sneha; Bajaj, Amrita; Londhe, Vaishali; Babul, Najib; Kao, Danny

2017-03-30

Topical film-forming metered dose spray formulations were designed for management of pain. Ropivacaine, a local anesthetic is explored for its topical efficacy in alleviating pain. Metered dose spray containers, organic solvents, film forming polymers and permeation enhancers were utilized to fabricate the Metered Dose topical spray. Factors like viscosity, spray pattern, spray angle, volume of actuation, droplet size distribution of the metered dose spray formulation and drying time, flexibility and wash-ability of the film formed after spraying were assessed. Permeation of the drug into the porcine skin was observed based on ex-vivo diffusion studies and confocal microscopy. The results indicated a high level of drug concentration in the skin layers. Anti-nociceptive efficacy of the formulations was assessed on Wistar rats by hot plate and tail flick tests, based on the response to pain perception. The results were comparable to the conventional lidocaine gel. Topical film forming sprays have the ability to provide an accurate, long lasting and patient compliant delivery of drugs on the skin as compared to conventional gels. Copyright © 2017 Elsevier B.V. All rights reserved.

SU-F-T-113: Inherent Functional Dependence of Spinal Cord Doses of Variable Irradiated Volumes in Spine SBRT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, L; Braunstein, S; Chiu, J

2016-06-15

Purpose: Spinal cord tolerance for SBRT has been recommended for the maximum point dose level or at irradiated volumes such as 0.35 mL or 10% of contoured volumes. In this study, we investigated an inherent functional relationship that associates these dose surrogates for irradiated spinal cord volumes of up to 3.0 mL. Methods: A hidden variable termed as Effective Dose Radius (EDR) was formulated based on a dose fall-off model to correlate dose at irradiated spinal cord volumes ranging from 0 mL (point maximum) to 3.0 mL. A cohort of 15 spine SBRT cases was randomly selected to derive anmore » EDR-parameterized formula. The mean prescription dose for the studied cases was 21.0±8.0 Gy (range, 10–40Gy) delivered in 3±1 fractions with target volumes of 39.1 ± 70.6 mL. Linear regression and variance analysis were performed for the fitting parameters of variable EDR values. Results: No direct correlation was found between the dose at maximum point and doses at variable spinal cord volumes. For example, Pearson R{sup 2} = 0.643 and R{sup 2}= 0.491 were obtained when correlating the point maximum dose with the spinal cord dose at 1 mL and 3 mL, respectively. However, near perfect correlation (R{sup 2} ≥0.99) was obtained when corresponding parameterized EDRs. Specifically, Pearson R{sup 2}= 0.996 and R{sup 2} = 0.990 were obtained when correlating EDR (maximum point dose) with EDR (dose at 1 mL) and EDR(dose at 3 mL), respectively. As a result, high confidence level look-up tables were established to correlate spinal cord doses at the maximum point to any finite irradiated volumes. Conclusion: An inherent functional relationship was demonstrated for spine SBRT. Such a relationship unifies dose surrogates at variable cord volumes and proves that a single dose surrogate (e.g. point maximum dose) is mathematically sufficient in constraining the overall spinal cord dose tolerance for SBRT.« less

Monte Carlo assessment of the finger shallow dose from direct contact with a microcentrifuge tube containing common biotechnology isotopes in solution.

PubMed

Cutright, Dan; Medich, David; Ring, Joseph

2012-04-01

Eppendorf tubes often are used in biomedical research labs and contain radioactive tracers. Although the associated direct contact finger doses are typically small, it is suggested (and in line with the principle of ALARA) to handle these tubes from the cap of the tube. When containing radioactive material, handling a tube near the bottom conical section would unnecessarily increase the skin dose to the fingers. This investigation modeled a 2.0-mL Eppendorf tube containing various individual beta emitting isotopes commonly used in a biomedical research environment (i.e., (14)C, (3)H, (131)I, (32)P, and (35)S) to determine the skin dose when directly handling the tube at the cap end and when handling it at the bottom conical section. The primary goal of this paper is to assess how significantly this dose is altered by handling geometry. The skin dose to a single finger was calculated with Monte Carlo simulations using MCNP5 and determined at a depth of 0.007 cm(2) in water averaged over 10 cm as described in 10CFR20. Results show that the dose rate may vary by as much as a factor of 700 depending on handling geometry.

Drinking water standard for tritium-what's the risk?

PubMed

Kocher, D C; Hoffman, F O

2011-09-01

This paper presents an assessment of lifetime risks of cancer incidence associated with the drinking water standard for tritium established by the U.S. Environmental Protection Agency (USEPA); this standard is an annual-average maximum contaminant level (MCL) of 740 Bq L(-1). This risk assessment has several defining characteristics: (1) an accounting of uncertainty in all parameters that relate a given concentration of tritium in drinking water to lifetime risk (except the number of days of consumption of drinking water in a year and the number of years of consumption) and an accounting of correlations of uncertain parameters to obtain probability distributions that represent uncertainty in estimated lifetime risks of cancer incidence; (2) inclusion of a radiation effectiveness factor (REF) to represent an increased biological effectiveness of low-energy electrons emitted in decay of tritium compared with high-energy photons; (3) use of recent estimates of risks of cancer incidence from exposure to high-energy photons, including the dependence of risks on an individual's gender and age, in the BEIR VII report; and (4) inclusion of risks of incidence of skin cancer, principally basal cell carcinoma. By assuming ingestion of tritium in drinking water at the MCL over an average life expectancy of 80 y in females and 75 y in males, 95% credibility intervals of lifetime risks of cancer incidence obtained in this assessment are (0.35, 12) × 10(-4) in females and (0.30, 15) × 10(-4) in males. Mean risks, which are considered to provide the best single measure of expected risks, are about 3 × 10(-4) in both genders. In comparison, USEPA's point estimate of the lifetime risk of cancer incidence, assuming a daily consumption of drinking water of 2 L over an average life expectancy of 75.2 y and excluding an REF for tritium and incidence of skin cancer, is 5.6 × 10(-5). Probability distributions of annual equivalent doses to the whole body associated with the drinking water standard for tritium also were obtained. Means and 97.5th percentiles of maximum annual doses to females and males, which occur at age <1 y, all are less than the annual equivalent dose of 40 μSv used by USEPA to establish the MCL.

[Sensitivity and specificity of prick skin test with two concentrations of standardized extract of Culex quinquefasciatus in allergic children].

PubMed

Castro-Almarales, Raúl Lázaro; Álvarez-Castelló, Mirta; Ronquillo-Díaz, Mercedes; Rodríguez-Canosa, José S; González-León, Mayda; Navarro-Viltre, Bárbara I; Betancourt-Mesia, Daniel; Enríquez-Domínguez, Irene; Reyes-Zamora, Mary Carmen; Oliva-Díaz, Yunia; Mateo-Morejón, Maytee; Labrada-Rosado, Alexis

2016-01-01

Diagnostic options for immune reactions to mosquito bites are limited. In Cuba, IgE-mediated reactions are frequently related to Culex quinquefasciatus bite. To determine the sensitivity and specificity of skin prick test with two doses of standardized extract in nitrogen protein units (PNU of Culex quinquefasciatus (BIOCEN, Cuba). An analytical study was conducted on 100 children between 2 and 15 years old. Fifty atopic patients with a history of allergy to mosquito bite and positive specific serum IgE Culex quinquefasciatus and fifty atopic patients without a history of allergy to mosquito bite and negative specific serum IgE to Culex quinquefasciatus. Skin prick tests (SPT) were performed by duplicates on the forearms of the patients. Investigated doses were 100 PNU/mL and 10 PNU/mL. SPT with the highest concentration obtained a mean wheal size of 22.09 mm2 and for lower doses of 8.09 mm2, a statistically significant difference (p=0.001, Student's t test). Positive skin test correlated in 100% of patients with the presence of specific IgE. Testing with both doses showed a 94% of specificity and 88% of sensitivity. The diagnostic accuracy of SPT using both doses of standardized extract was similar, which justifies its use for diagnosis of sensitization to Culex quinquefasciatus in patients with symptoms of allergy to mosquito bite.

Ultraviolet A within Sunlight Induces Mutations in the Epidermal Basal Layer of Engineered Human Skin

PubMed Central

Huang, Xiao Xuan; Bernerd, Françoise; Halliday, Gary Mark

2009-01-01

The ultraviolet B (UVB) waveband within sunlight is an important carcinogen; however, UVA is also likely to be involved. By ascribing mutations to being either UVB or UVA induced, we have previously shown that human skin cancers contain similar numbers of UVB- and UVA-induced mutations, and, importantly, the UVA mutations were at the base of the epidermis of the tumors. To determine whether these mutations occurred in response to UV, we exposed engineered human skin (EHS) to UVA, UVB, or a mixture that resembled sunlight, and then detected mutations by both denaturing high-performance liquid chromatography and DNA sequencing. EHS resembles human skin, modeling differential waveband penetration to the basal, dividing keratinocytes. We administered only four low doses of UV exposure. Both UVA and UVB induced p53 mutations in irradiated EHS, suggesting that sunlight doses that are achievable during normal daily activities are mutagenic. UVA- but not UVB-induced mutations predominated in the basal epidermis that contains dividing keratinocytes and are thought to give rise to skin tumors. These studies indicate that both UVA and UVB at physiological doses are mutagenic to keratinocytes in EHS. PMID:19264911

Phase I study of topical epigallocatechin-3-gallate (EGCG) in patients with breast cancer receiving adjuvant radiotherapy.

PubMed

Zhao, Hanxi; Zhu, Wanqi; Jia, Li; Sun, Xiaorong; Chen, Guanxuan; Zhao, Xianguang; Li, Xiaolin; Meng, Xiangjiao; Kong, Lingling; Xing, Ligang; Yu, Jinming

2016-01-01

The purpose of this study was to investigate the safety, tolerability and preliminary effectiveness of topical epigallocatechin-3-gallate (EGCG) for radiation dermatitis in patients with breast cancer receiving adjuvant radiotherapy. Patients with breast cancer who received radiotherapy to the chest wall after mastectomy were enrolled. EGCG solution was sprayed to the radiation field from the initiation of Grade 1 radiation dermatitis until 2 weeks after completion of radiotherapy. EGCG concentration escalated from 40 to 660 μmol l(-1) in 7 levels with 3-6 patients in each level. EGCG toxicity was graded using the NCI (National Cancer Institute Common Terminology Criteria for Adverse Events) v. 3.0. Any adverse event >Grade 1 attributed to EGCG was considered dose-limiting toxicity. The maximum tolerated dose was defined as the dose level that induced dose-limiting toxicity in more than one-third of patients at a given cohort. Radiation dermatitis was recorded weekly by the Radiation Therapy Oncology Group scoring and patient-reported symptoms. From March 2012 to August 2013, 24 patients were enrolled. Acute skin redness was observed in 1 patient and considered to be associated with the EGCG treatment at 140 μmol l(-1) level. Three more patients were enrolled at this level and did not experience toxicity to EGCG. The dose escalation stopped at 660 μmol l(-1). No other reported acute toxicity was associated with EGCG. Grade 2 radiation dermatitis was observed in eight patients during or after radiotherapy, but all decreased to Grade 1 after EGCG treatments. Patient-reported symptom scores were significantly decreased at 2 weeks after the end of radiotherapy in pain, burning, itching and tenderness, p < 0.05. The topical administration of EGCG was well tolerated and the maximum tolerated dose was not found. EGCG may be effective in treating radiation dermatitis with preliminary investigation. EGCG solution seemed to be feasible for treating radiation dermatitis in patients with breast cancer after mastectomy. It should be tested as a way to reduce radiation-induced normal tissue toxicity and complications in future years.

Skin toxicity from external beam radiation therapy in breast cancer patients: protective effects of Resveratrol, Lycopene, Vitamin C and anthocianin (Ixor®).

PubMed

Di Franco, Rossella; Calvanese, MariaGrazia; Murino, Paola; Manzo, Roberto; Guida, Cesare; Di Gennaro, Davide; Anania, Caterina; Ravo, Vincenzo

2012-01-30

This is an observational study and the aim is to evaluate the effect of dietary supplements based on Resveratrol, Lycopene, Vitamin C and Anthocyanins (Ixor®) in reducing skin toxicity due to external beam radiotherapy in patients affected by breast cancer. 71 patients were enrolled and they were divided in two different groups: a control group (CG) of 41 patients treated with prophylactic topical therapy based on hyaluronic acid and topical steroid therapy in case of occurrence of radiodermatitis, and a Ixor-Group (IG) of 30 patients treated also with an oral therapy based on Resveratrol, Lycopene, Vitamin C and Anthocyanin (Ixor®) at a dose of 2 tablets/day, starting from 10 days before the radiation treatment until 10 days after the end of treatment. Skin toxicity has been related to PTV, to breast volume that received a radiation dose equal or lower than 107%, included between 107% and 110%, or greater than 110% of the prescribed dose. Moreover it's been studied the relationship between skin toxicity and the chemotherapy schedule used before treatment. We calculated in both groups the percentage of patients who had a skin toxicity of grade 2 or 3 (according to RTOG scale). Absolute risk reduction (ARR), relative risk (RR) and odds ratio (OR) have been calculated for each relationship. Control Group (CG) patients with a PTV > 500 ml presented skin toxicity G2 + G3 in 30% of cases, versus 25% of Ixor-Group (IG) [OR 0.77]. In patients with a PTV < 500 ml G2 + G3 toxicity was 0% in the IG compared to 18% in CG (OR 0.23). When Dmax was less than or equal to 107% of the prescribed dose skin toxicity was G2 + G3 in 12.5% in CG, versus 0% in IG (OR 0.73), instead when Dmax was included between 107 and 110% of the prescribed dose, G2 + G3 skin toxicity was 35% in CG and 21% in IG (OR 0.50). In patients undergoing chemotherapy with anthracyclines and taxanes, G2 + G3 toxicity was 27% in CG, against 20% in IG (OR 0.68). The protective effect of Resveratrol, Lycopene, Vitamin C and Anthocyanin (Ixor®) is more detected in patients with PTV < 500 ml, when Dmax reaches values lower or equal to 107%, but not exceeding 110% of the prescribed dose, and in patients undergoing adjuvant chemotherapy with anthracyclines and taxanes.

Low-dose mitomycin C, etoposide, and cisplatin for invasive vulvar Paget's disease.

PubMed

Watanabe, Yoh; Hoshiai, H; Ueda, H; Nakai, H; Obata, K; Noda, K

2002-01-01

We report the effect of low-dose mitomycin C, etoposide, and cisplatin (low-dose MEP) therapy for three patients with invasive vulvar Paget's disease (invasive VPD) who declined radical vulvectomy and skin grafting. One patient achieved a complete response, while the other two showed partial responses (PR) without grade 3 or 4 adverse effects. The two patients with PR were undergone partial vulvectomy and inguinal lymph node dissection. All patients have no sign of recurrence for 10 months after chemotherapy. Our present results suggest that low-dose MEP is an effective and safe chemotherapy for invasive VPD and low-dose MEP may significantly improve postoperative quality of life in patients with invasive VPD by avoiding extensive vulvar resection and skin grafting.

Experimental testing and constitutive modeling of the mechanical properties of the swine skin tissue.

PubMed

Łagan, Sylwia D; Liber-Kneć, Aneta

2017-01-01

The aim of the study was an estimation of the possibility of using hyperelastic material models to fit experimental data obtained in the tensile test for the swine skin tissue. The uniaxial tensile tests of samples taken from the abdomen and back of a pig was carried out. The mechanical properties of the skin such as the mean Young's modulus, the mean maximum stress and the mean maximum elongation were calculated. The experimental data have been used to identify the parameters in specific strain-energy functions given in seven constitutive models of hyperelastic materials: neo-Hookean, Mooney-Rivlin, Ogden, Yeoh, Martins, Humphrey and Veronda-Westmann. An analysis of errors in fitting of theoretical and experimental data was done. Comparison of load -displacement curves for the back and abdomen regions of skin taken showed a different scope of both the mean maximum loading forces and the mean maximum elongation. Samples which have been prepared from the abdominal area had lower values of the mean maximum load compared to samples from the spine area. The reverse trend was observed during the analysis of the values of elongation. An analysis of the accuracy of model fitting to the experimental data showed that, the least accurate were the model of neo- -Hookean, model of Mooney-Rivlin for the abdominal region and model of Veronda-Westmann for the spine region. An analysis of seven hyperelastic material models showed good correlations between the experimental and the theoretical data for five models.

Critical Dose of Internal Organs Internal Exposure - 13471

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grigoryan, G.; Amirjanyan, A.; Grigoryan, N.

2013-07-01

The health threat posed by radionuclides has stimulated increased efforts to developed characterization on the biological behavior of radionuclides in humans in all ages. In an effort motivated largely by the Chernobyl nuclear accident, the International Commission on Radiological Protection (ICRP) is assembling a set of age specific biokinetic models for environmentally important radioelements. Radioactive substances in the air, mainly through the respiratory system and digestive tract, is inside the body. Radioactive substances are unevenly distributed in various organs and tissues. Therefore, the degree of damage will depend not only on the dose of radiation have but also on themore » critical organ, which is the most accumulation of radioactive substances, which leads to the defeat of the entire human body. The main objective of radiation protection, to avoid exceeding the maximum permissible doses of external and internal exposure of a person to prevent the physical and genetic damage people. The maximum tolerated dose (MTD) of radiation is called a dose of radiation a person in uniform getting her for 50 years does not cause changes in the health of the exposed individual and his progeny. The following classification of critical organs, depending on the category of exposure on their degree of sensitivity to radiation: First group: the whole body, gonads and red bone marrow; Second group: muscle, fat, liver, kidney, spleen, gastrointestinal tract, lungs and lens of the eye; The third group: bone, thyroid and skin; Fourth group: the hands, forearms, feet. MTD exposure whole body, gonads and bone marrow represent the maximum exposures (5 rem per year) experienced by people in their normal activities. The purpose of this article is intended dose received from various internal organs of the radionuclides that may enter the body by inhalation, and gastrointestinal tract. The biokinetic model describes the time dependent distribution and excretion of different radionuclides that have intake into the organism or absorbed into blood. Transport of different radionuclides between compartments is assumed to follow first order kinetics provided the concentration in red blood cells (RBCs) stays below a nonlinear threshold concentration. When the concentration in RBCs exceeds that threshold, the transfer rate from diffusible plasma to RBCs is assumed to decrease as the concentration in RBCs increases. For the calculations used capabilities AMBER by using the traces of radionuclides in the body. Model for the transfer of radionuclides in the body has been built on the basis of existing models at AMBER for lead. (authors)« less

SU-F-T-323: A Post-Mastectomy Radiation Therapy Dose Distribution Study Using Nanodots and Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qian, X; Vaidya, K; Puckett, L

Purpose: In post-mastectomy radiation therapy (RT), skin dose must be accurately estimated to assess skin reactions such as erythema, desquamation and necrosis. Planning systems cannot always provide accurate dosimetry for target volumes distal to skin. Therefore, in-vivo dosimetry is necessary. A female anthropomorphic phantom was used with optically stimulated luminescence dosimeters (nanoDots) to measure dose to chest wall skin. In addition, EBT2 films was employed to measure dose to left lung and heart in post-mastectomy RT. Methods: Films and nanoDots were calibrated under full buildup conditions at 100cm SAD for 6MV photons. Five pieces of films were placed between slabsmore » of Rando phantom to assess dose to left lung and heart. Two layers of 0.5cm thick bolus were used to cover the whole left chest. Six pairs of nanoDots were placed at medical and lateral aspects on the bolus surface, between the 0.5cm bolus layers, and under the bolus. Three control nanoDots were placed on chest wall to quantify imaging dose. The phantom was CT scanned with all dosimeters in place, and treatment planning was performed with tangential fields (200cGy). All dosimeters were contoured on CT and dose was extracted. NanoDots were read using nanoDot reader and films were scanned using film scanner. The measured and calculated doses were tabulated. Results: Dose to 12 nanoDots were evaluated. Dose variance for surface nanoDots were +3.8%, +2.7%, −5% and −9.8%. Those at lateral positions, with greater beam obliquity had larger variance than the medial positions. A similar trend was observed for other nanoDots (Table1). Point doses from films for heart and the left lung were 112.7cGy and 108.7cGy, with +10.2% and +9.04% deviation from calculated values, respectively. Conclusion: Dosimetry provided by the advanced planning system was verified using NanoDots and films. Both nanoDots and films provided good estimation of dose distribution in post-mastectomy RT.« less

Development of the mechanical properties of engineered skin substitutes after grafting to full-thickness wounds.

PubMed

Sander, Edward A; Lynch, Kaari A; Boyce, Steven T

2014-05-01

Engineered skin substitutes (ESSs) have been reported to close full-thickness burn wounds but are subject to loss from mechanical shear due to their deficiencies in tensile strength and elasticity. Hypothetically, if the mechanical properties of ESS matched those of native skin, losses due to shear or fracture could be reduced. To consider modifications of the composition of ESS to improve homology with native skin, biomechanical analyses of the current composition of ESS were performed. ESSs consist of a degradable biopolymer scaffold of type I collagen and chondroitin-sulfate (CGS) that is populated sequentially with cultured human dermal fibroblasts (hF) and epidermal keratinocytes (hK). In the current study, the hydrated biopolymer scaffold (CGS), the scaffold populated with hF dermal skin substitute (DSS), or the complete ESS were evaluated mechanically for linear stiffness (N/mm), ultimate tensile load at failure (N), maximum extension at failure (mm), and energy absorbed up to the point of failure (N-mm). These biomechanical end points were also used to evaluate ESS at six weeks after grafting to full-thickness skin wounds in athymic mice and compared to murine autograft or excised murine skin. The data showed statistically significant differences (p <0.05) between ESS in vitro and after grafting for all four structural properties. Grafted ESS differed statistically from murine autograft with respect to maximum extension at failure, and from intact murine skin with respect to linear stiffness and maximum extension. These results demonstrate rapid changes in mechanical properties of ESS after grafting that are comparable to murine autograft. These values provide instruction for improvement of the biomechanical properties of ESS in vitro that may reduce clinical morbidity from graft loss.

Skin photoprotective and antiageing effects of a combination of rosemary (Rosmarinus officinalis) and grapefruit (Citrus paradisi) polyphenols

PubMed Central

Nobile, Vincenzo; Michelotti, Angela; Cestone, Enza; Caturla, Nuria; Castillo, Julián; Benavente-García, Obdulio; Pérez-Sánchez, Almudena; Micol, Vicente

2016-01-01

Background Plant polyphenols have been found to be effective in preventing ultraviolet radiation (UVR)-induced skin alterations. A dietary approach based of these compounds could be a safe and effective method to provide a continuous adjunctive photoprotection measure. In a previous study, a combination of rosemary (Rosmarinus officinalis) and grapefruit (Citrus paradisi) extracts has exhibited potential photoprotective effects both in skin cell model and in a human pilot trial. Objective We investigated the efficacy of a combination of rosemary (R. officinalis) and grapefruit (C. paradisi) in decreasing the individual susceptibility to UVR exposure (redness and lipoperoxides) and in improving skin wrinkledness and elasticity. Design A randomised, parallel group study was carried out on 90 subjects. Furthermore, a pilot, randomised, crossover study was carried out on five subjects. Female subjects having skin phototype from I to III and showing mild to moderate chrono- or photoageing clinical signs were enrolled in both studies. Skin redness (a* value of CIELab colour space) after UVB exposure to 1 minimal erythemal dose (MED) was assessed in the pilot study, while MED, lipoperoxides (malondialdehyde) skin content, wrinkle depth (image analysis), and skin elasticity (suction and elongation method) were measured in the main study. Results Treated subjects showed a decrease of the UVB- and UVA-induced skin alterations (decreased skin redness and lipoperoxides) and an improvement of skin wrinkledness and elasticity. No differences were found between the 100 and 250 mg extracts doses, indicating a plateau effect starting from 100 mg extracts dose. Some of the positive effects were noted as short as 2 weeks of product consumption. Conclusions The long-term oral intake of Nutroxsun™ can be considered to be a complementary nutrition strategy to avoid the negative effects of sun exposure. The putative mechanism for these effects is most likely to take place through the inhibition of UVR-induced reactive oxygen species and the concomitant inflammatory markers (lipoperoxides and cytokines) together with their direct action on intracellular signalling pathways. PMID:27374032

Human skin absorption of Bis-2-(chloroethyl)sulphide (sulphur mustard) in vitro.

PubMed

Chilcott, R P; Jenner, J; Carrick, W; Hotchkiss, S A; Rice, P

2000-01-01

The purpose of this study was to measure the absorption and intra-epidermal fate of 35S-radiolabelled sulphur mustard (35SM) in human breast skin in vitro. Skin (full-thickness or heat-separated epidermis) was placed into static diffusion cells and was exposed to droplets of liquid 35SM or saturated 35SM vapour. Amounts of 35SM penetrating the skin were measured from which skin absorption rates were calculated. Unbound radiolabel was washed from the surface, extracted from the skin and analysed to determine the identity of the radiolabelled species in order to measure the extent of hydrolysis of sulphur mustard. Penetration rates of liquid 35SM measured in vitro (71-294 microg cm(-2) h(-1)) were in agreement with those measured previously in vivo using human volunteers (60-240 microg cm(-2) h(-1)). Rates of liquid 35SM skin absorption under occluded, infinite dose conditions were highest through heat-separated epidermal membranes (294+/-58 microg cm(-2) h(-1)) and lowest through full-thickness skin (71+/-14 microg cm(-2) h(-1)). Fluxes of saturated 35SM vapour (110+/-75 microg cm(-2) h(-1)) through heat-separated membranes were similar to those previously measured through human forearm skin in vivo (162 microg cm(-2) h(-1)). Although hydrolysis of 35SM did occur, both on the surface and within the skin, it accounted for only a small percentage of the total applied dose (<2.7+/-1.2%). The difference in total amount of liquid 35SM penetrated between occluded and unoccluded conditions in vitro (79+/-14%) was similar to that lost as vapour from unoccluded skin in vivo (80%). A substantial reservoir of 35SM (14-36% of the applied dose) was measured within heat-separated epidermal membranes for up to 24 h which may have significant implications for the management of personnel exposed to sulphur mustard.

Penetration of levofloxacin into skin tissue after oral administration of multiple 750 mg once-daily doses.

PubMed

Chow, A T; Chen, A; Lattime, H; Morgan, N; Wong, F; Fowler, C; Williams, R R

2002-04-01

To probe the pharmacokinetic basis for the use of levofloxacin for complicated skin and skin-structure infections (SSSIs) at a once-daily dosage of 750 mg by investigating its penetration into skin tissue. Ten healthy volunteers were administered three oral, once-daily 750 mg doses of levofloxacin, and levofloxacin concentrations were subsequently measured over time (0.5-24 h) in skin-punch biopsy tissue and plasma. Skin tissue concentrations consistently exceeded those in plasma at every time point, with tissue/plasma ratios of 1.37 +/- 0.81 for peak concentration and 1.97 +/- 0.35 for area under the concentration versus time curve. Three of the ten subjects reported treatment-emergent adverse events (AEs) that were considered unrelated to treatment. An 11th subject who had enrolled in the study withdrew after AEs of mild severity that were possibly related to the study drug. The results support the clinical usage of levofloxacin 750 mg once-daily for complicated SSSIs.

The effects of grape seeds polyphenols on SKH-1 mice skin irradiated with multiple doses of UV-B.

PubMed

Filip, Adriana; Daicoviciu, Doina; Clichici, Simona; Bolfa, Pompei; Catoi, Cornel; Baldea, Ioana; Bolojan, Laura; Olteanu, Diana; Muresan, Adriana; Postescu, I D

2011-11-03

The study investigated the protective activity of red grape seeds (Vitis vinifera L, Burgund Mare variety) (BM) extracts in vivo on multiple doses of ultraviolet radiation (UV)-B-induced deleterious effects in SKH-1 mice skin. Eighty 8-weeks-old female SKH-1 mice were divided into 8 groups: control, vehicle, UV-B irradiated, vehicle+UV-B irradiated, BM 2.5mg polyphenols (PF)/cm(2)+UV-B irradiated, BM 4 mg PF/cm(2)+UV-B irradiated, UV-B+BM 2.5mg PF/cm(2), UV-B+BM 4 mg PF/cm(2). The extract was applied topically before or after each UV-B exposure (240 mJ/cm(2)), for 10 days consecutively. The antioxidant activity of BM extract is higher than gallic acid (k(BM)=0.017, k(gallic acid)=0.013). Multiple doses of UV-B generated the formation of cyclobutane pyrimidine dimers (CPDs) and sunburn cells, increased glutathione peroxidase (GPx) and catalase (CAT) activities respectively glutathione (GSH) and IL-1β levels in skin. In group treated with 2.5mg PF/cm(2) before UV-B irradiation BM extract inhibited UV-B-induced sunburn cells, restored the superoxide dismutase (MnSOD) activity, increased insignificantly CAT and GPx activities and reduced IL-1β level. The BM 4.0 mg PF/cm(2) treatment decreased GSH level and reduced the percentage of CPDs positive cells in skin. Both doses of BM extract administered after UV-B irradiation increased the MnSOD and GPx activities and reduced the formation of sunburn cells in skin. Our results suggest that BM extract might be a potential chemo-preventive candidate in reducing the oxidative stress and apoptosis induced by multiple doses of UV-B in skin. Copyright © 2011 Elsevier B.V. All rights reserved.

WE-DE-201-11: Sensitivity and Specificity of Verification Methods Based On Total Reference Air Kerma (TRAK) Or On User Provided Dose Points for Graphically Planned Skin HDR Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Damato, A; Devlin, P; Bhagwat, M

Purpose: To investigate the sensitivity and specificity of a novel verification methodology for image-guided skin HDR brachytherapy plans using a TRAK-based reasonableness test, compared to a typical manual verification methodology. Methods: Two methodologies were used to flag treatment plans necessitating additional review due to a potential discrepancy of 3 mm between planned dose and clinical target in the skin. Manual verification was used to calculate the discrepancy between the average dose to points positioned at time of planning representative of the prescribed depth and the expected prescription dose. Automatic verification was used to calculate the discrepancy between TRAK of themore » clinical plan and its expected value, which was calculated using standard plans with varying curvatures, ranging from flat to cylindrically circumferential. A plan was flagged if a discrepancy >10% was observed. Sensitivity and specificity were calculated using as a criteria for true positive that >10% of plan dwells had a distance to prescription dose >1 mm different than prescription depth (3 mm + size of applicator). All HDR image-based skin brachytherapy plans treated at our institution in 2013 were analyzed. Results: 108 surface applicator plans to treat skin of the face, scalp, limbs, feet, hands or abdomen were analyzed. Median number of catheters was 19 (range, 4 to 71) and median number of dwells was 257 (range, 20 to 1100). Sensitivity/specificity were 57%/78% for manual and 70%/89% for automatic verification. Conclusion: A check based on expected TRAK value is feasible for irregularly shaped, image-guided skin HDR brachytherapy. This test yielded higher sensitivity and specificity than a test based on the identification of representative points, and can be implemented with a dedicated calculation code or with pre-calculated lookup tables of ideally shaped, uniform surface applicators.« less

Comparison of light absorption levels with different skin phantoms and the Monte Carlo simulation using Fourier-domain optical coherence tomography

NASA Astrophysics Data System (ADS)

Jo, Hang Chan; Kim, Jae Hun; Kim, Dae Yu

2018-02-01

Dermatologic patients have various skin characteristics such as skin tone and pigmentation color. However most studies on laser ablation and treatment only considered laser operating conditions like wavelength, output power and pulse duration. The laser ablation arises from photothermal effect by photon energy absorption. Chromophores like melanin exist as the absorber in the skin. In this study, we painted color to mimic chromophores on in-vivo and in-vitro skin models to demonstrate influence on the laser ablation by skin color. Water-based pens were used to paint color. Cross sectional images of the laser ablation were acquired by Fourier-domain optical coherence tomography (Fd-OCT). Light source to make ablation was a Q-switch diode-pumped Nd:YVO4 nanosecond laser (532nm central wavelength). Irradiated light energy dose of the laser could not make ablation craters in the control group. However experimental groups showed craters with same irradiation light energy dose. These results show painting on skin increased tissue damage by absorption in painted color without dyeing cells or tissues.

Nanoparticle-Enabled Transdermal Drug Delivery Systems for Enhanced Dose Control and Tissue Targeting.

PubMed

Palmer, Brian C; DeLouise, Lisa A

2016-12-15

Transdermal drug delivery systems have been around for decades, and current technologies (e.g., patches, ointments, and creams) enhance the skin permeation of low molecular weight, lipophilic drugs that are efficacious at low doses. The objective of current transdermal drug delivery research is to discover ways to enhance skin penetration of larger, hydrophilic drugs and macromolecules for disease treatment and vaccination. Nanocarriers made of lipids, metals, or polymers have been successfully used to increase penetration of drugs or vaccines, control drug release, and target drugs to specific areas of skin in vivo. While more research is needed to identify the safety of nanocarriers, this technology has the potential to expand the use of transdermal routes of administration to a wide array of therapeutics. Here, we review the current state of nanoparticle skin delivery systems with special emphasis on targeting skin diseases.

Nanoparticle enabled transdermal drug delivery systems for enhanced dose control and tissue targeting

PubMed Central

Palmer, Brian C.; DeLouise, Lisa A.

2017-01-01

Transdermal drug delivery systems have been around for decades, and current technologies (e.g. patches, ointments, and creams) enhance the skin permeation of low molecular weight, lipophilic drugs that are efficacious at low doses. The objective of current transdermal drug delivery research is to discover ways to enhance skin penetration of larger, hydrophilic drugs and macromolecules for disease treatment and vaccination. Nanocarriers made of lipids, metals, or polymers have been successfully used to increase penetration of drugs or vaccines, control drug release, and target drugs to specific areas of skin in vivo. While more research is needed to identify the safety of nanocarriers, this technology has the potential to expand the use of transdermal routes of administration to a wide array of therapeutics. Here, we review the current state of nanoparticle skin delivery systems with special emphasis on targeting skin diseases. PMID:27983701

Ceramide 1 and ceramide 3 act synergistically on skin hydration and the transepidermal water loss of sodium lauryl sulfate-irritated skin.

PubMed

Huang, Huey-Chun; Chang, Tsong-Min

2008-08-01

Stratum corneum intercellular lipids, such as ceramides, play an important role in the regulation of skin water barrier homeostasis and water-holding capacity. Aim To evaluate the potential water retention capacity of control emulsion and three oil-in-water (o/w) emulsions containing ceramide 1, ceramide 3, or both. Fifteen healthy Asian women (age, 20-30 years) with healthy skin, pretreated with sodium lauryl sulfate (SLS), applied the tested emulsions twice daily over a period of 28 days. Skin hydration and transepidermal water loss (TEWL) values were measured on the indicated days with a Corneometer(R)825 and a TEWAMETER TM210, respectively. The maximum increase in skin humidity was reached after 4 weeks, with values of 21.9 +/- 1.8% and 8.9 +/- 0.9% for emulsion C and control emulsion, respectively. The maximum decrease in TEWL was also reached after 4 weeks, with values of 36.7 +/- 4.7% and 5.1 +/- 0.8% for the same emulsions. It can be concluded that all the tested ceramide-containing emulsions improved skin barrier function when compared with untreated skin. There was some indication that ceramides 1 and 3 contained in emulsion C might exert a beneficial synergistic effect on skin biochemical properties, such as skin hydration and TEWL, and play a key role in the protection mechanism against SLS irritation.

Evaluation of dose variation during total skin electron irradiation using thermoluminescent dosimeters.

PubMed

Weaver, R D; Gerbi, B J; Dusenbery, K E

1995-09-30

To determine acceptable dose variation using thermoluminescent dosimeters (TLD) in the treatment of Mycosis Fungoides with total skin electron beam (TSEB) irradiation. From 1983 to 1993, 22 patients were treated with total skin electron beam therapy in the standing position. A six-field technique was used to deliver 2 Gy in two days, treating 4 days per week, to a total dose of 35 to 40 Gy using a degraded 9 MeV electron beam. Thermoluminescent dosimeters were placed on several locations of the body and the results recorded. The variations in these readings were analyzed to determine normal dose variation for various body locations during TSEB. The dose to flat surfaces of the body was essentially the same as the dose to the prescription point. The dose to tangential surfaces was within +/- 10% of the prescription dose, but the readings showed much more variation (up to 24%). Thin areas of the body showed large deviations from the prescription dose along with a large amount of variation in the readings (up to 22%). Special areas of the body, such as the perineum and eyelid, showed large deviations from the prescription dose with very large (up to 40%) variations in the readings. The TLD results of this study will be used as a quality assurance check for all new patients treated with TSEB. The results of the TLDs will be compared with this baseline study to determine if the delivered dose is within acceptable ranges. If the TLD results fall outside the acceptable limits established above, then the patient position can be modified or the technique itself evaluated.

Use of a graphics processing unit (GPU) to facilitate real-time 3D graphic presentation of the patient skin-dose distribution during fluoroscopic interventional procedures

PubMed Central

Rana, Vijay; Rudin, Stephen; Bednarek, Daniel R.

2012-01-01

We have developed a dose-tracking system (DTS) that calculates the radiation dose to the patient’s skin in real-time by acquiring exposure parameters and imaging-system-geometry from the digital bus on a Toshiba Infinix C-arm unit. The cumulative dose values are then displayed as a color map on an OpenGL-based 3D graphic of the patient for immediate feedback to the interventionalist. Determination of those elements on the surface of the patient 3D-graphic that intersect the beam and calculation of the dose for these elements in real time demands fast computation. Reducing the size of the elements results in more computation load on the computer processor and therefore a tradeoff occurs between the resolution of the patient graphic and the real-time performance of the DTS. The speed of the DTS for calculating dose to the skin is limited by the central processing unit (CPU) and can be improved by using the parallel processing power of a graphics processing unit (GPU). Here, we compare the performance speed of GPU-based DTS software to that of the current CPU-based software as a function of the resolution of the patient graphics. Results show a tremendous improvement in speed using the GPU. While an increase in the spatial resolution of the patient graphics resulted in slowing down the computational speed of the DTS on the CPU, the speed of the GPU-based DTS was hardly affected. This GPU-based DTS can be a powerful tool for providing accurate, real-time feedback about patient skin-dose to physicians while performing interventional procedures. PMID:24027616

Increased dose near the skin due to electromagnetic surface beacon transponder.

PubMed

Ahn, Kang-Hyun; Manger, Ryan; Halpern, Howard J; Aydogan, Bulent

2015-05-08

The purpose of this study was to evaluate the increased dose near the skin from an electromagnetic surface beacon transponder, which is used for localization and tracking organ motion. The bolus effect due to the copper coil surface beacon was evaluated with radiographic film measurements and Monte Carlo simulations. Various beam incidence angles were evaluated for both 6 MV and 18 MV experimentally. We performed simulations using a general-purpose Monte Carlo code MCNPX (Monte Carlo N-Particle) to supplement the experimental data. We modeled the surface beacon geometry using the actual mass of the glass vial and copper coil placed in its L-shaped polyethylene terephthalate tubing casing. Film dosimetry measured factors of 2.2 and 3.0 enhancement in the surface dose for normally incident 6 MV and 18 MV beams, respectively. Although surface dose further increased with incidence angle, the relative contribution from the bolus effect was reduced at the oblique incidence. The enhancement factors were 1.5 and 1.8 for 6 MV and 18 MV, respectively, at an incidence angle of 60°. Monte Carlo simulation confirmed the experimental results and indicated that the epidermal skin dose can reach approximately 50% of the dose at dmax at normal incidence. The overall effect could be acceptable considering the skin dose enhancement is confined to a small area (~ 1 cm2), and can be further reduced by using an opposite beam technique. Further clinical studies are justified in order to study the dosimetric benefit versus possible cosmetic effects of the surface beacon. One such clinical situation would be intact breast radiation therapy, especially large-breasted women.

Use of a graphics processing unit (GPU) to facilitate real-time 3D graphic presentation of the patient skin-dose distribution during fluoroscopic interventional procedures.

PubMed

Rana, Vijay; Rudin, Stephen; Bednarek, Daniel R

2012-02-23

We have developed a dose-tracking system (DTS) that calculates the radiation dose to the patient's skin in real-time by acquiring exposure parameters and imaging-system-geometry from the digital bus on a Toshiba Infinix C-arm unit. The cumulative dose values are then displayed as a color map on an OpenGL-based 3D graphic of the patient for immediate feedback to the interventionalist. Determination of those elements on the surface of the patient 3D-graphic that intersect the beam and calculation of the dose for these elements in real time demands fast computation. Reducing the size of the elements results in more computation load on the computer processor and therefore a tradeoff occurs between the resolution of the patient graphic and the real-time performance of the DTS. The speed of the DTS for calculating dose to the skin is limited by the central processing unit (CPU) and can be improved by using the parallel processing power of a graphics processing unit (GPU). Here, we compare the performance speed of GPU-based DTS software to that of the current CPU-based software as a function of the resolution of the patient graphics. Results show a tremendous improvement in speed using the GPU. While an increase in the spatial resolution of the patient graphics resulted in slowing down the computational speed of the DTS on the CPU, the speed of the GPU-based DTS was hardly affected. This GPU-based DTS can be a powerful tool for providing accurate, real-time feedback about patient skin-dose to physicians while performing interventional procedures.

Determination of minimal erythema dose and anomalous reactions to UVA radiation by skin phototype.

PubMed

Pérez Ferriols, A; Aguilera, J; Aguilera, P; de Argila, D; Barnadas, M A; de Cabo, X; Carrrascosa, J M; de Gálvez Aranda, M V; Gardeazábal, J; Giménez-Arnau, A; Lecha, M; Lorente, J; Martínez-Lozano, J A; Rodríguez Granados, M T; Sola, Y; Utrillas, M P

2014-10-01

Phototesting is a technique that assesses the skin's sensitivity to UV radiation by determining the smallest dose of radiation capable of inducing erythema (minimal erythema dose [MED]) and anomalous responses to UV-A radiation. No phototesting protocol guidelines have been published to date. This was a multicenter prospective cohort study in which 232 healthy volunteers were recruited at 9 hospitals. Phototests were carried out with solar simulators or fluorescent broadband UV-B lamps. Each individual received a total of 5 or 6 incremental doses of erythemal radiation and 4 doses of UV-A radiation. The results were read at 24hours. At hospitals where solar simulators were used, the mean (SD) MED values were 23 (8), 28 (4), 35 (4), and 51 (6) mJ/cm(2) for skin phototypes i to iv, respectively. At hospitals where broadband UV-B lamps were used, these values were 28 (5), 32 (3), and 34 (5) mJ/cm(2) for phototypes ii to iv, respectively. MED values lower than 7, 19, 27, and 38 mJ/cm(2) obtained with solar simulators were considered to indicate a pathologic response for phototypes I to IV, respectively. MED values lower than 18, 24, and 24mJ/cm(2) obtained with broadband UV-B lamps were considered to indicate a pathologic response for phototypes ii to iv, respectively. No anomalous responses were observed at UV-A radiation doses of up to 20J/cm(2). Results were homogeneous across centers, making it possible to standardize diagnostic phototesting for the various skin phototypes and establish threshold doses that define anomalous responses to UV radiation. Copyright © 2014 Elsevier España, S.L.U. y AEDV. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niu, Y; Becker, S; Mutaf, Y

Purpose: The first GammaPod™ unit, a dedicated prone stereotactic treatment device for early stage breast cancer, has been installed and commissioned at University of Maryland School of Medicine. The objective of this study was to investigate potential dosimetric impact of inaccurate breast contour. Methods: In GammaPod treatments, patient’s beast is immobilized by a breast cup device (BCID) throughout the entire same-day imaging and treatment procedure. 28 different BICD sizes are available to accommodate patients with varying breast sizes. A mild suction helps breast tissue to conform to the shape of the cup with selected size. In treatment planning, dose calculationmore » utilizes previously calculated dose distributions for available cup geometry rather than the breast shape from CT image. Patient CT images with breast cups indicate minor geometric discrepancy between the matched shape of the cup and the breast contour, i.e., the contour size is larger or smaller. In order to investigate the dosimetric impact of these discrepancies, we simulated such discrepancies and reassessed the dose to target as well as skin. Results: In vicinity of skin, hot/cold spots were found when matched cup size was smaller/larger than patient’s breast after comparing the corrected dose profiles from Monte Carlo simulation with the planned dose from TPS. The overdosing/underdosing of target could yield point dose differences as large as 5% due to these setup errors (D95 changes within 2.5%). Maximal skin dose was overestimated/underestimated up to 25%/45% when matched cup size was larger/smaller than real breast contour. Conclusion: The dosimetric evaluation suggests substantial underdosing/overdosing with inaccurate cup geometry during planning, which is acceptable for current clinical trial. Further studies are needed to evaluate such impact to treating small volume close to skin.« less

SU-F-T-432: Magnetic Field Dose Effects for Various Radiation Beam Geometries for Patients Treated with Hypofractionated Partial Breast Irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim-Reinders, S; University of Toronto, Department of Physics; Keller, B

Purpose: Hypofractionated partial breast irradiation (HPBI) is being used at our clinic to treat inoperable breast cancer patients who have advanced disease. We are investigating how these patients could benefit from being treated in an MRI-linac, where real-time daily MRI tumor imaging and plan adaptation would be possible. As a first step, this study evaluates the dosimetric impact of the magnetic field for different radiation beam geometries on relevant OARs. Methods: Five patients previously treated using HPBI were selected. Six treatment plans were generated for each patient, evaluating three beam geometries (VMAT, IMRT, 3DCRT) with and without B{sub 0}=1.5 T.more » The Monaco TPS was used with the Elekta MRI-Linac beam model, where the magnetic field is orthogonal to the radiation beam. All plans were re-scaled to the same isocoverage with a prescription of 40Gy/5 to the PTV. Plans were evaluated for the effect of the magnetic field and beam modality on skin V{sub 3} {sub 0}, lung V{sub 2} {sub 0} and mean heart dose. Results: Averaged over all patients, skin V{sub 3} {sub 0}for 3DCRT was higher than VMAT and IMRT (by +22% and +21%, with B{sub 0}-ON). The magnetic field caused larger increases in skin V{sub 3} {sub 0}for 3DCRT (+8%) than VMAT (+3%) and IMRT (+4%) compared with B{sub 0}-OFF. With B{sub 0}-ON, 3DCRT had a markedly lower mean heart dose than VMAT (by 538cGy) and IMRT (by 562cGy); for lung V{sub 2} {sub 0}, 3DCRT had a marginally lower dose than VMAT (by −2.2%) and IMRT (also −2.2%). The magnetic field had minimal effect on the mean heart dose and lung V{sub 2} {sub 0} for all geometries. Conclusion: The decreased skin dose in VMAT and IMRT can potentially mitigate the effects of skin reactions for HPBI in an MRI-linac. This study illustrated that more beam angles may result in lower skin toxicity and better tumor conformality, with the trade-off of elevated heart and lung doses. We are receiving funding support from Elekta.« less

Hyperspectral Surface Analysis for Ripeness Estimation and Quick UV-C Surface Treatments for Preservation of Bananas

NASA Astrophysics Data System (ADS)

Zhao, W.; Yang, Zh.; Chen, Zh.; Liu, J.; Wang, W. Ch.; Zheng, W. Yu.

2016-05-01

This study aimed to determine the ripeness of bananas using hyperspectral surface analysis and how a rapid UV-C (ultraviolet-C light) surface treatment could reduce decay. The surface of the banana fruit and its stages of maturity were studied using a hyperspectral imaging technique in the visible and near infrared (370-1000 nm) regions. The vselected color ratios from these spectral images were used for classifying the whole banana into immature, ripe, half-ripe and overripe stages. By using a BP neural network, models based on the wavelengths were developed to predict quality attributes. The mean discrimination rate was 98.17%. The surface of the fresh bananas was treated with UV-C at dosages from 15-55 μW/cm2. The visual qualities with or without UV-C treatment were compared using the image, the chromatic aberration test, the firmness test and the area of black spot on the banana skin. The results showed that high dosages of UV-C damaged the banana skin, while low dosages were more efficient at delaying changes in the relative brightness of the skin. The maximum UV-C treatment dose for satisfactory banana preservation was between 21 and 24 μW/cm2. These results could help to improve the visual quality of bananas and to classify their ripeness more easily.

Dose Distribution in Cone-Beam Breast Computed Tomography: An Experimental Phantom Study

NASA Astrophysics Data System (ADS)

Russo, Paolo; Lauria, Adele; Mettivier, Giovanni; Montesi, Maria Cristina; Villani, Natalia

2010-02-01

We measured the spatial distribution of absorbed dose in a 14 cm diameter PMMA half-ellipsoid phantom simulating the uncompressed breast, using an X-ray cone-beam breast computed tomography apparatus, assembled for laboratory tests. Thermoluminescent dosimeters (TLD-100) were placed inside the phantom in six positions, both axially and at the phantom periphery. To study the dose distribution inside the PMMA phantom two experimental setups were adopted with effective energies in the range 28.7-44.4 keV. Different values of effective energies were obtained by combining different configurations of added Cu filtration (0.05 mm or 0.2 mm) and tube voltages (from 50 kVp to 80 kVp). Dose values obtained by TLDs in different positions inside the PMMA are reported. To evaluate the dose distribution in the breast shaped volume, the values measured were normalized to the one obtained in the inner position inside the phantom. Measurements with a low energy setup show a gradual increment of dose going from the "chest wall" to the "nipple" (63% more at the "nipple" compared to the central position). Likewise, a gradual increment is observed going from the breast axis toward the periphery (82% more at the "skin" compared to the central position). A more uniform distribution of dose inside the PMMA was obtained with a high energy setup (the maximum variation was 33% at 35.5 keV effective energy in the radial direction). The most uniform distribution is obtained at 44.4 keV. The results of this study show how the dose is distributed: it varies as a function of effective energy of the incident X-ray beam and as a function of the position inside the volume (axial or peripheral position).

Feasibility study of entrance and exit dose measurements at the contra lateral breast with alanine/electron spin resonance dosimetry in volumetric modulated radiotherapy of breast cancer

NASA Astrophysics Data System (ADS)

Wagner, Daniela M.; Hüttenrauch, Petra; Anton, Mathias; von Voigts-Rhetz, Philip; Zink, Klemens; Wolff, Hendrik A.

2017-07-01

The Physikalisch-Technische Bundesanstalt has established a secondary standard measurement system for the dose to water, D W, based on alanine/ESR (Anton et al 2013 Phys. Med. Biol. 58 3259-82). The aim of this study was to test the established measurement system for the out-of-field measurements of inpatients with breast cancer. A set of five alanine pellets were affixed to the skin of each patient at the contra lateral breast beginning at the sternum and extending over the mammilla to the distal surface. During 28 fractions with 2.2 Gy per fraction, the accumulated dose was measured in four patients. A cone beam computer tomography (CBCT) scan was generated for setup purposes before every treatment. The reference CT dataset was registered rigidly and deformably to the CBCT dataset for 28 fractions. To take the actual alanine pellet position into account, the dose distribution was calculated for every fraction using the Acuros XB algorithm. The results of the ESR measurements were compared to the calculated doses. The maximum dose measured at the sternum was 19.9 Gy  ±  0.4 Gy, decreasing to 6.8 Gy  ±  0.2 Gy at the mammilla and 4.5 Gy  ±  0.1 Gy at the distal surface of the contra lateral breast. The absolute differences between the calculated and measured doses ranged from  -1.9 Gy to 0.9 Gy. No systematic error could be seen. It was possible to achieve a combined standard uncertainty of 1.63% for D W  =  5 Gy for the measured dose. The alanine/ESR method is feasible for in vivo measurements.

Pharmacokinetics and tolerability of human mouse chimeric anti-CD22 monoclonal antibody in Chinese patients with CD22-positive non-Hodgkin lymphoma.

PubMed

Li, Su; Zhang, Dongsheng; Sun, Jian; Li, Zhinming; Deng, Liting; Zou, Benyan; Zhan, Jing; Jiang, Wenqi

2012-01-01

The safety and pharmacokinetics assessment of antibodies targeting CD22 (e.g., epratuzumab) have been established in western Caucasian populations, but there are no reports of the effects in Chinese populations. This dose-escalation study examines the safety, pharmacokinetics and biologic effects of multiple doses of anti-CD22 human-murine chimeric monoclonal antibody SM03 in 21 Chinese patients with CD22-positive non-Hodgkin lymphoma. Most of drug-related adverse events (AEs) were mild and reversible. Two patients experienced serious AEs (hemorrhage); one patient had grade 4 neutropenia; one patient had asymptomatic grade III prolongation of activated partial thromboplastin time (APTT). Major AEs included fever (71%), prolongation of APTT (42.8%), leukocytopenia (44.4%), alanine transaminase elevation (28.6%), elevated serum creatinine (23.8%) and injection site skin redness (14.3%). Circulating B cells transiently decreased without significant effects on T cells or immunoglobulin levels. Pharmacokinetic data revealed that mean maximum observed SM03 concentration and mean AUC from time zero to infinity increased in a dose-dependent manner up to 360 mg/m (2) SM03. Mean clearance was similar at doses ≤ 360 mg/m (2) and decreased significantly at dose 480 mg/m (2), supporting saturation of B-cell binding at 360 mg/m (2). Across all dose levels and histologies, one patient achieved partial response at 480 mg/m (2) dose; 14 patients had stable disease as best response and four patients progressed. Overall, SM03 was tolerated at doses ranging from 60-480 mg/m (2) and had potential efficacy in Chinese patients with follicular lymphoma.

Experimental study on skin irritation of bone spur powder on rabbit

NASA Astrophysics Data System (ADS)

Ma, Zhenzhen; Zhang, Xuhui; Hao, Shaojun; Shen, Huiling; Wang, Huamin; Ji, Xianghui; Zhang, Zhengchen; Huang, Youling

2018-04-01

To observe the effect of bone powder of rabbit skin, provide the basis for the safety of clinical use of bone powder, 24 rabbits were randomly divided into 6 groups, complete skin test and damaged skin test each divided into 3 groups (n=4), high, low, 3 doses tested daily administered 1 times, continuous administration for 7 days, in 24 hours after the last administration of drug residues, wash with warm water, the removal of L hours after drug for 24 hours, 48 hours, 72 hours and seventh days, observed and recorded to apply position before administration and administration during the skin no erythema and edema, and observe the smear Parts of any pigmentation, bleeding, rough skin or thin skin etc., record the occurrence time and duration time. Through comparative observation, intact skin group before administration and dosing period, there were no erythema and edema, pigmentation, bleeding, rough skin or thin skin etc., there is no difference with the control group; the damaged skin group after administration of 1 to 5 days, each rabbit skin there are different degrees of erythema and edema, especially to skin injury after 24-48 hours is obvious, 2 days (48 hours) after 4 days gradually reduced, significantly subsided after 6 days, erythema and edema phenomenon subsided completely, not out of blood, pigmentation, rough skin or thin skin and so on. The bone spur powder has no irritation on the intact skin of rabbits. The bone spur powder has moderate irritation on the damaged skin of rabbits, but after 48 hours, the stimulation reaction subsided spontaneously, which is caused by the inflammatory reaction caused by skin injury, rather than the medication. The bone spur powder is safe for clinical use.

Maximum dose rate is a determinant of hypothyroidism after 131I therapy of Graves' disease but the total thyroid absorbed dose is not.

PubMed

Krohn, Thomas; Hänscheid, Heribert; Müller, Berthold; Behrendt, Florian F; Heinzel, Alexander; Mottaghy, Felix M; Verburg, Frederik A

2014-11-01

The determinants of successful (131)I therapy of Graves' disease (GD) are unclear. To relate dosimetry parameters to outcome of therapy to identify significant determinants eu- and/or hypothyroidism after (131)I therapy in patients with GD. A retrospective study in which 206 Patients with GD treated in University Hospital between November 1999 and January 2011. All received (131)I therapy aiming at a total absorbed dose to the thyroid of 250 Gy based on pre-therapeutic dosimetry. Post-therapy dosimetric thyroid measurements were performed twice daily until discharge. From these measurements, thyroid (131)I half-life, the total thyroid absorbed dose, and the maximum dose rate after (131)I administration were calculated. In all, 48.5% of patients were hypothyroid and 28.6% of patients were euthyroid after (131)I therapy. In univariate analysis, nonhyperthyroid and hyperthyroid patients only differed by sex. A lower thyroid mass, a higher activity per gram thyroid tissue, a shorter effective thyroidal (131)I half-life, and a higher maximum dose rate, but not the total thyroid absorbed dose, were significantly associated with hypothyroidism. In multivariate analysis, the maximum dose rate remained the only significant determinant of hypothyroidism (P < .001). Maximum dose rates of 2.2 Gy/h and higher were associated with a 100% hypothyroidism rate. Not the total thyroid absorbed dose, but the maximum dose rate is a determinant of successfully achieving hypothyroidism in Graves' disease. Dosimetric concepts aiming at a specific total thyroid absorbed dose will therefore require reconsideration if our data are confirmed prospectively.

Effect of in vivo jet fuel exposure on subsequent in vitro dermal absorption of individual aromatic and aliphatic hydrocarbon fuel constituents.

PubMed

Muhammad, F; Monteiro-Riviere, N A; Baynes, R E; Riviere, J E

2005-05-14

The percutaneous absorption of topically applied jet fuel hydrocarbons (HC) through skin previously exposed to jet fuel has not been investigated, although this exposure scenario is the occupational norm. Pigs were exposed to JP-8 jet fuel-soaked cotton fabrics for 1 and 4 d with repeated daily exposures. Preexposed and unexposed skin was then dermatomed and placed in flow-through in vitro diffusion cells. Five cells with exposed skin and four cells with unexposed skin were dosed with a mixture of 14 different HC consisting of nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, ethyl benzene, o-xylene, trimethyl benzene (TMB), cyclohexyl benzene (CHB), naphthalene, and dimethyl naphthalene (DMN) in water + ethanol (50:50) as diluent. Another five cells containing only JP-8-exposed skin were dosed solely with diluent in order to determine the skin retention of jet fuel HC. The absorption parameters of flux, diffusivity, and permeability were calculated for the studied HC. The data indicated that there was a two-fold and four-fold increase in absorption of specific aromatic HC like ethyl benzene, o-xylene, and TMB through 1- and 4-dJP-8 preexposed skin, respectively. Similarly, dodecane and tridecane were absorbed more in 4-d than 1-dJP-8 preexposed skin experiments. The absorption of naphthalene and DMN was 1.5 times greater than the controls in both 1- and 4-d preexposures. CHB, naphthalene, and DMN had significant persistent skin retention in 4-d preexposures as compared to 1-d exposures that might leave skin capable of further absorption several days postexposure. The possible mechanism of an increase in HC absorption in fuel preexposed skin may be via lipid extraction from the stratum corneum as indicated by Fourier transform infrared (FTIR) spectroscopy. This study suggests that the preexposure of skin to jet fuel enhances the subsequent in vitro percutaneous absorption of HC, so single-dose absorption data for jet fuel HC from naive skin may not be optimal to predict the toxic potential for repeated exposures. For certain compounds, persistent absorption may occur days after the initial exposure.

Effective dose equivalent on the ninth Shuttle--Mir mission (STS-91)

NASA Technical Reports Server (NTRS)

Yasuda, H.; Badhwar, G. D.; Komiyama, T.; Fujitaka, K.

2000-01-01

Organ and tissue doses and effective dose equivalent were measured using a life-size human phantom on the ninth Shuttle-Mir Mission (STS-91, June 1998), a 9.8-day spaceflight at low-Earth orbit (about 400 km in altitude and 51.65 degrees in inclination). The doses were measured at 59 positions using a combination of thermoluminescent dosimeters of Mg(2)SiO(4):Tb (TDMS) and plastic nuclear track detectors (PNTD). In correcting the change in efficiency of the TDMS, it was assumed that reduction of efficiency is attributed predominantly to HZE particles with energy greater than 100 MeV nucleon(-1). A conservative calibration curve was chosen for determining LET from the PNTD track-formation sensitivities. The organ and tissue absorbed doses during the mission ranged from 1.7 to 2.7 mGy and varied by a factor of 1.6. The dose equivalent ranged from 3.4 to 5.2 mSv and varied by a factor of 1.5 on the basis of the dependence of Q on LET in the 1990 recommendations of the ICRP. The effective quality factor (Q(e)) varied from 1.7 to 2.4. The dose equivalents for several radiation-sensitive organs, such as the stomach, lung, gonad and breast, were not significantly different from the skin dose equivalent (H(skin)). The effective dose equivalent was evaluated as 4.1 mSv, which was about 90% of the H(skin).

Construction of boundary-surface-based Chinese female astronaut computational phantom and proton dose estimation

PubMed Central

Sun, Wenjuan; JIA, Xianghong; XIE, Tianwu; XU, Feng; LIU, Qian

2013-01-01

With the rapid development of China's space industry, the importance of radiation protection is increasingly prominent. To provide relevant dose data, we first developed the Visible Chinese Human adult Female (VCH-F) phantom, and performed further modifications to generate the VCH-F Astronaut (VCH-FA) phantom, incorporating statistical body characteristics data from the first batch of Chinese female astronauts as well as reference organ mass data from the International Commission on Radiological Protection (ICRP; both within 1% relative error). Based on cryosection images, the original phantom was constructed via Non-Uniform Rational B-Spline (NURBS) boundary surfaces to strengthen the deformability for fitting the body parameters of Chinese female astronauts. The VCH-FA phantom was voxelized at a resolution of 2 × 2 × 4 mm3for radioactive particle transport simulations from isotropic protons with energies of 5000–10 000 MeV in Monte Carlo N-Particle eXtended (MCNPX) code. To investigate discrepancies caused by anatomical variations and other factors, the obtained doses were compared with corresponding values from other phantoms and sex-averaged doses. Dose differences were observed among phantom calculation results, especially for effective dose with low-energy protons. Local skin thickness shifts the breast dose curve toward high energy, but has little impact on inner organs. Under a shielding layer, organ dose reduction is greater for skin than for other organs. The calculated skin dose per day closely approximates measurement data obtained in low-Earth orbit (LEO). PMID:23135158

Comparison of wavelength-dependent penetration depths of lasers in different types of skin in photodynamic therapy

NASA Astrophysics Data System (ADS)

Mustafa, F. H.; Jaafar, M. S.

2013-03-01

The determination of the penetration depth of laser light with different sources wavelengths into human skin is one of the preconditions of improving the photodynamic therapy (PDT) procedure for skin diseases. This research is planned to explore which wavelengths would be the most advantageous for use in PDT for superficial skin diseases, and to demonstrate that the red laser exposure of 635 nm wavelength is a suitable choice for all skin types in PDT. A realistic skin model (RSM) in the Advanced Systems Analysis Program (ASAP) software has been used to create different types of skin and to simulate laser sources with wavelengths of 635, 532, 405, 365, 308 and 295 nm. The penetration depths of different kinds of laser into the skin as well as their transmission have been calculated. Comparison of the depth of penetration of different wavelengths for all types of skin has been made. A large variation is found in the penetration depth of laser lights in all skin types. The transmission of lasers on the epidermis and dermis in different skin types occur, and the transmission dose changes significantly with the skin depths. The results of the present study provide a basis for understanding the penetration depth of laser in various skin colors and the responses of the skin to laser to improve dose-drug activation in PDT. The differences in spectral transmission between the red laser and the other lasers suggest that the red laser could be a suitable laser for all skin types.

Modulation of cathepsin G expression in severe atopic dermatitis following medium-dose UVA1 phototherapy

PubMed Central

Breuckmann, Frank; von Kobyletzki, Gregor; Avermaete, Annelies; Kreuter, Alexander; Altmeyer, Peter; Gambichler, Thilo

2002-01-01

Background During the last decade, medium-dose UVA1 phototherapy (50 J/cm2) has achieved great value within the treatment of severe atopic dermatitis (AD). The purpose of our study was to investigate to what extent UVA1 irradiation is able to modulate the status of protease activity by the use of a monoclonal antibody labeling cathepsin G. Methods In order to further elucidate the mechanisms by which medium-dose UVA1 irradiation leads to an improvement of skin status in patients with AD, biopsy specimens from 15 patients before and after treatment were analyzed immunohistochemically for proteolytic activation. Results Compared to lesional skin of patients with AD before UVA1 irradiation, the number of cells positive for cathepsin G within the dermal infiltrate decreased significantly after treatment. The decrease of cathepsin G+ cells was closely linked to a substantial clinical improvement in skin condition. Conclusions In summary, our findings demonstrated that medium-dose UVA1 irradiation leads to a modulation of the expression of cathepsin G in the dermal inflammatory infiltrate in patients with severe AD. Cathepsin G may attack laminin, proteoglycans, collagen I and insoluble fibronectin, to provoke proinflammatory events, to degrade the basement membrane, to destroy the tissue inhibitor of metalloproteinases and to increase the endothelial permeability. Therefore, its down-regulation by UVA1 phototherapy may induce the reduction of skin inflammation as well as improvement of the skin condition. PMID:12204095

Chestnut astringent skin extract, an alpha-amylase inhibitor, retards carbohydrate absorption in rats and humans.

PubMed

Tsujita, Takahiro; Takaku, Takeshi; Suzuki, Tsuneo

2008-02-01

Inhibitors of carbohydrate-hydrolyzing enzyme play an important role to control postprandial blood glucose levels. In this paper, we investigated the effect of an ethanol extract from chestnut astringent skin (CAS) on alpha-amylase. Chestnut astringent skin extract strongly inhibited human and porcine pancreatic alpha-amylase. We also investigated the effect of CAS extract on carbohydrate absorption in rats and humans. Oral administration of CAS extract to normal rats fed corn starch (2 g/kg body weight), significantly suppressed the increase of blood glucose levels after starch loading in a dose-dependent manner. The effective dose of CAS extract required to achieve 20 and 40% suppression of the rise in blood glucose level was estimated to be 40 and 155 mg/kg body weight, respectively. Chestnut astringent skin extract also suppressed the rise in plasma insulin level and the fall in plasma non-esterified fatty acid level. In the type 2 diabetic rat model, CAS extract significantly suppressed the rise in blood glucose level after starch loading in a dose-dependent manner. Chestnut astringent skin extract also suppressed the rise in plasma glucose level after boiled rice loading in a dose-dependent manner in humans. The amount of CAS extract required to achieve 11 and 23% suppression in the rise in plasma glucose level was 300 and 600 mg/person, respectively. These results suggest that CAS extract retards absorption of carbohydrate and reduces post-prandial hyperglycemia.

Fluralaner as a single dose oral treatment for Caparinia tripilis in a pygmy African hedgehog.

PubMed

Romero, Camilo; Sheinberg Waisburd, Galia; Pineda, Jocelyn; Heredia, Rafael; Yarto, Enrique; Cordero, Alberto M

2017-12-01

African pygmy hedgehogs (Atelerix albiventris) are popular pets belonging to the Erinaceidae family of spined mammals. Amongst the most common skin diseases occurring in this species is infestation caused by the mite Caparinia spp. Due to their skin anatomy and spiny coat, detection of skin lesions in these hedgehogs can be difficult. This may result in delays in seeking medical care, which may lead to secondary bacterial infection and self-inflicted trauma. Multiple therapies have been used in the treatment of this skin condition including ivermectin, amitraz, fipronil and selamectin. A drug which could be administered as a single oral dose would be advantageous to these pets and their owners. To evaluate the effect of a single oral dose (15 mg/kg) of fluralaner on Caparinia tripilis infestation in the African pygmy hedgehog. A 10-month-old African pygmy hedgehog weighing 184 g. Response to treatment was monitored by dermatological examination and superficial skin scrapings repeated at 7, 14, 21, 30, 60, 90 and 120 days following fluralaner administration. On Day 7 after treatment, adult mites were observed exhibiting normal movement. On Day 14, only dead mites were observed. No life stages of the mites were found after Day 21. A single oral dose at 15 mg/kg of fluralaner was effective within 21 days after treatment for capariniasis in this case. Further studies are required to evaluate the drug's safety and toxicology in hedgehogs, and to confirm efficacy. © 2017 ESVD and ACVD.

Decreasing Skin Graft Contraction through Topical Wound Bed Preparation with Anti-Inflammatory Agents

DTIC Science & Technology

2017-10-01

factor in the development of skin graft contraction. Using a porcine model of skin graft contraction, we will screen for anti- inflammatory agents (dose...Award Number: W81XWH-14-2-0153 TITLE: Decreasing Skin Graft Contraction through Topical Wound Bed Preparation with Anti-Inflammatory Agents ...09/14/2017 4. TITLE AND SUBTITLE “Decreasing Skin Graft Contraction through Topical Wound Bed Preparation with Anti-Inflammatory Agents ” 5a

How accurately can the peak skin dose in fluoroscopy be determined using indirect dose metrics?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, A. Kyle, E-mail: kyle.jones@mdanderson.org; Ensor, Joe E.; Pasciak, Alexander S.

Purpose: Skin dosimetry is important for fluoroscopically-guided interventions, as peak skin doses (PSD) that result in skin reactions can be reached during these procedures. There is no consensus as to whether or not indirect skin dosimetry is sufficiently accurate for fluoroscopically-guided interventions. However, measuring PSD with film is difficult and the decision to do so must be madea priori. The purpose of this study was to assess the accuracy of different types of indirect dose estimates and to determine if PSD can be calculated within ±50% using indirect dose metrics for embolization procedures. Methods: PSD were measured directly using radiochromicmore » film for 41 consecutive embolization procedures at two sites. Indirect dose metrics from the procedures were collected, including reference air kerma. Four different estimates of PSD were calculated from the indirect dose metrics and compared along with reference air kerma to the measured PSD for each case. The four indirect estimates included a standard calculation method, the use of detailed information from the radiation dose structured report, and two simplified calculation methods based on the standard method. Indirect dosimetry results were compared with direct measurements, including an analysis of uncertainty associated with film dosimetry. Factors affecting the accuracy of the different indirect estimates were examined. Results: When using the standard calculation method, calculated PSD were within ±35% for all 41 procedures studied. Calculated PSD were within ±50% for a simplified method using a single source-to-patient distance for all calculations. Reference air kerma was within ±50% for all but one procedure. Cases for which reference air kerma or calculated PSD exhibited large (±35%) differences from the measured PSD were analyzed, and two main causative factors were identified: unusually small or large source-to-patient distances and large contributions to reference air kerma from cone beam computed tomography or acquisition runs acquired at large primary gantry angles. When calculated uncertainty limits [−12.8%, 10%] were applied to directly measured PSD, most indirect PSD estimates remained within ±50% of the measured PSD. Conclusions: Using indirect dose metrics, PSD can be determined within ±35% for embolization procedures. Reference air kerma can be used without modification to set notification limits and substantial radiation dose levels, provided the displayed reference air kerma is accurate. These results can reasonably be extended to similar procedures, including vascular and interventional oncology. Considering these results, film dosimetry is likely an unnecessary effort for these types of procedures when indirect dose metrics are available.« less

Serum testosterone levels in non-dosed females after secondary exposure to 1.62% testosterone gel: effects of clothing barrier on testosterone absorption.

PubMed

Stahlman, Jodi; Britto, Margaret; Fitzpatrick, Sherahe; McWhirter, Cecilia; Testino, Samuel A; Brennan, John J; Zumbrunnen, Troy L

2012-02-01

To evaluate secondary exposure of testosterone transferred to females from a male partner, dosed with 1.62% testosterone gel after direct skin-to-skin contact with the application site, and to investigate the effect of wearing a t-shirt on testosterone transfer. Across three studies, a total of 72 healthy males applied 5.0 g 1.62% testosterone gel to their abdomen alone, upper arms/shoulders alone, or a combination of their upper arms/shoulders and abdomen (single dose or once daily for 7 days). Male-female contact occurred 2 or 12 hours after testosterone gel application, with males either wearing or not wearing a t-shirt. There were 15 minutes of supervised contact with the application site between the male and his female partner. Blood samples were collected over a 24 hour period in females for assessment of serum testosterone levels at baseline and after contact. Pharmacokinetic parameters included C(max) (maximum serum concentration), AUC(0-24) (area under the serum concentration-time curve from 0-24 hours), and C(av) (time-averaged concentration over the 24-hour period post-contact). Subjects were monitored for adverse events. CLINICAL TRIAL REGISTRATION NCT NUMBERS: Study 1 was not registered (first subject enrolled 8 March 2007); Study 2: 00998933; Study 3, 01130298. Testosterone levels (C(av) and C(max)) in females increased 86-185% from baseline after direct abdominal skin contact, although C(av) levels remained within female eugonadal range. Testosterone concentrations returned to baseline within 48 hours after last skin contact. A t-shirt barrier reduced testosterone transfer by approximately 40-48% when 5.0 g of testosterone gel was applied to the abdomen alone. A t-shirt barrier prevented transfer when 5.0 g of testosterone gel was applied to the upper arms and shoulders or to a combination of the upper arms and shoulders and the abdomen (C(max) and C(av) increased by approximately 5-11%). No major safety events were observed during the studies. There is a risk of testosterone transfer from males using 1.62% testosterone gel to others who come in contact with the application site for at least 12 hours after application. Secondary exposure can be mitigated by means of a t-shirt barrier. Women for these studies were not selected by menopausal status. The study designs were intended to simulate exaggerated conditions of transfer.

High dose rate brachytherapy with customized applicators for malignant facial skin lesions.

PubMed

Jumeau, R; Renard-Oldrini, S; Courrech, F; Buchheit, I; Oldrini, G; Vogin, G; Peiffert, D

2016-07-01

Brachytherapy is a well-known treatment in the management of skin tumors. For facial or scalp lesions, applicators have been developed to deliver non-invasive treatment. We present cases treated with customized applicators with high dose rate system. Patients with poor performance status treated for malignant skin lesions of the scalp or the facial skin between 2011 and 2014 were studied. Afterloading devices were chosen between Freiburg(®) Flap, silicone-mold or wax applicators. The clinical target volume (CTV) was created by adding margins to lesions (10mm to 20mm). The dose schedules were 25Gy in five fractions for postoperative lesions, 30Gy in six fractions for exclusive treatments and a single session of 8Gy could be considered for palliative treatments. In 30 months, 11 patients received a treatment for a total of 12 lesions. The median age was 80 years. The median follow-up was 17 months and the 2-year local control rate was 91%. The mean CTV surface was 41.1cm(2) with a mean thickness of 6.1mm. We conceived three wax applicators, used our silicone-mold eight times and the Freiburg(®) Flap one time. We observed only low-grade radiodermitis (grade I: 50%, grade II: 33%), and no high-grade skin toxicity. High dose rate brachytherapy with customized applicators for facial skin and scalp lesions is efficient and safe. It is a good modality to treat complex lesions in patients unfit for invasive treatment. Copyright © 2016 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

Factors significantly increasing or inhibiting early stages of malignant melanoma (M.M.) and non-invasive evaluation of new treatment by ingestion and external application of optimal doses of the most effective anti-M.M. substances: haritaki, cilantro, vitamin D3, nori, EPA with DHA, & application of special (+) solar energy stored paper, which reduced the M.M. active area & asbestos rapidly.

PubMed

Omura, Yoshiaki; Jones, Marilyn; Duvvi, Harsha; Paluch, Kamila; Shimotsuura, Yasuhiro; Ohki, Motomu

2013-01-01

Sterilizing the pre-cancer skin of malignant melanoma (M.M.) with 70% Isopropyl alcohol intensified malignancy & the malignant response extended to surrounding normal looking skin, while sterilizing with 80% (vodka) or 12% (plum wine) ethyl alcohol completely inhibited M.M. in the area (both effects lasted for about 90 minutes initially). Burnt food (bread, vegetables, meat, and fish), a variety of smoked & non-smoked fish-skin, many animal's skin, pepper, Vitamin C over 75 mg, mango, pineapple, coconut, almond, sugars, Saccharine & Aspartame, garlic, onion, etc & Electromagnetic field from cellular phones worsened M.M. & induced abnormal M.M. response of surrounding skin. We found the following factors inhibit early stage of M.M. significantly: 1) Increasing normal cell telomere, by taking 500 mg Haritaki, often reached between 400-1150 ng& gradually diminished, but the M.M. response was completely inhibited until normal cell telomeres are reduced to 150 ng, which takes 6-8 hours. More than 70 mg Vitamin C, Orange Juice, & other high Vitamin C containing substances shouldn't be taken because they completely inhibit the effects of Haritaki. 2) We found Chrysotile asbestos & Tremolite asbestos (% of the Chrysotile amount) coexist. A special Cilantro tablet was used to remove asbestos & some toxic metals. 3) Vitamin D3 400 I.U. has a maximum inhibiting effect on M.M. but 800 I.U. or higher promotes malignancy. 4) Noricontaining Iodine, etc., was used. 5) EPA 180 mm with DHA 120 mg was most effectively used after metastasis to the surrounding skin was eliminated. When we combined 1 Cilantro tablet & Vitamin D3 400 I.U. withsmall Nori pieces & EPA with DHA, the effect of complete inhibition of M.M. lasted 9-11 hours. When these anti-M.M.substances (Haritaki, Vitamin D3, Cilantro, Nori, EPA. with DHA) were taken together, the effect lasted 12-14 hoursand M.M. involvement in surrounding normal-looking skin disappeared rapidly & original dark brown or black are as satisfying "ABCD" of M.M. completely fell off. Both oral & frequent external application of mixed solution of plum wine & the same combination of anti-M.M. substances can be used as very effective treatment by taking 2-3 times daily. Additional application of special (+) Solar Energy Stored Paper reduced asbestos & accelerated reduction of M.M. positive area rapidly. This method with individualized optimal doses has also been successfully applied to treat several other types of malignancies.

Dosimetric comparison between intra-cavitary breast brachytherapy techniques for accelerated partial breast irradiation and a novel stereotactic radiotherapy device for breast cancer: GammaPod™

NASA Astrophysics Data System (ADS)

Ödén, Jakob; Toma-Dasu, Iuliana; Yu, Cedric X.; Feigenberg, Steven J.; Regine, William F.; Mutaf, Yildirim D.

2013-07-01

The GammaPod™ device, manufactured by Xcision Medical Systems, is a novel stereotactic breast irradiation device. It consists of a hemispherical source carrier containing 36 Cobalt-60 sources, a tungsten collimator with two built-in collimation sizes, a dynamically controlled patient support table and a breast immobilization cup also functioning as the stereotactic frame for the patient. The dosimetric output of the GammaPod™ was modelled using a Monte Carlo based treatment planning system. For the comparison, three-dimensional (3D) models of commonly used intra-cavitary breast brachytherapy techniques utilizing single lumen and multi-lumen balloon as well as peripheral catheter multi-lumen implant devices were created and corresponding 3D dose calculations were performed using the American Association of Physicists in Medicine Task Group-43 formalism. Dose distributions for clinically relevant target volumes were optimized using dosimetric goals set forth in the National Surgical Adjuvant Breast and Bowel Project Protocol B-39. For clinical scenarios assuming similar target sizes and proximity to critical organs, dose coverage, dose fall-off profiles beyond the target and skin doses at given distances beyond the target were calculated for GammaPod™ and compared with the doses achievable by the brachytherapy techniques. The dosimetric goals within the protocol guidelines were fulfilled for all target sizes and irradiation techniques. For central targets, at small distances from the target edge (up to approximately 1 cm) the brachytherapy techniques generally have a steeper dose fall-off gradient compared to GammaPod™ and at longer distances (more than about 1 cm) the relation is generally observed to be opposite. For targets close to the skin, the relative skin doses were considerably lower for GammaPod™ than for any of the brachytherapy techniques. In conclusion, GammaPod™ allows adequate and more uniform dose coverage to centrally and peripherally located targets with an acceptable dose fall-off and lower relative skin dose than the brachytherapy techniques considered in this study.

Evaluation of Low-Dose Ultraviolet Light C for Reduction of Select ESKAPE Pathogens in a Canine Skin and Muscle Model.

PubMed

Dujowich, Mauricio; Case, J Brad; Ellison, Gary; Wellehan, James F X

2016-08-01

This study aimed at comparing the ability of low-dose UVC, 0.05% chlorhexidine, and combined UVC with 0.05% chlorhexidine to reduce colony-forming units (CFUs) on select ESKAPE pathogens (Staphylococcus aureus, Klebsiella pneumoniae, and Enterococcus faecium) in a canine skin and muscle model. Surgical site infections (SSIs) result in increased morbidity and cost. UVC damages DNA, rendering bacteria nonviable and does not discriminate between drug-sensitive and multi-drug-resistant organisms. Specimens were inoculated with one of three pathogens. Samples were treated with a 254 nm UVC mercury lamp or a 270 nm UVC LED light at 0.015, 0.03, or 0.04 J/cm(2) doses; 0.05% and 2% chlorhexidine were used as positive controls. To evaluate synergism, 0.05% chlorhexidine was used with 0.015 J/cm(2) of UVC. CFUs were counted and compared against the negative control. There were no significant differences in CFU counts between samples of the same tissue type treated with different light sources of the same UVC dose. UVC significantly decreased CFUs when compared against all negative controls in both skin and muscle. There was no consistently superior bactericidal UVC dose identified for individual bacteria or for tissue type. The bactericidal activity of UVC at 0.015 J/cm(2) versus 0.05% chlorhexidine was not different in muscle for any bacteria. The bactericidal activity of UVC at 0.015 J/cm(2) was superior to 0.05% chlorhexidine in skin for S. aureus and K. pneumonia, but not E. faecium. Combination of UVC and 0.05% chlorhexidine showed synergy against E. faecium when evaluated on skin. Low-dose UVC shows promise as a rapid, effective, and synergistic means of reducing bacterial burdens, which may decrease the incidence of SSIs. It should be further evaluated for use when 2% chlorhexidine would be contraindicated or impractical, such as open wounds or surgical sites.

SU-G-201-07: Dosimetric Verification of a 3D Printed HDR Skin Brachytherapy Applicator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rasmussen, K; Stanley, D; Eng, T

Purpose: The use of radiation as a treatment modality for skin cancer has increased significantly over the last decade with standardized applicators. Utilizing 3D printing, the ability to make applicators specifically designed for each patient’s anatomy has become economically feasible. With this in mind it was the aim of this study to determine the dosimetric accuracy of a 3-D printed HDR brachytherapy applicator for the skin. Methods: A CT reference image was used to generate a custom applicator based on an anthropomorphic head and neck phantom. To create the applicator a 1cm expansion anteriorly with 0.5cmX0.5cm trenches on the outermore » surface that were spaced 1cm sup-inf to accommodate standard 6F flexible catheters. The applicator was printed using PLA material using a printrbot simple printer. A treatment plan optimized to deliver a clinically representative volume was created in Oncentra and delivered with a nucletron afterloader. Measurements were made using TLDs and EBT3 gafchromic film that were placed between the applicator and the phantom’s forehead. An additional piece of film was also used to qualitatively asses the dose distribution in the transverse plane. Using a standard vaginal cylinder and bolus, a standardized curve correlating TLD and film exposure-to-radiation dose was established by irradiating film to known doses (200,500,700 cGy) at a 3.5 cm radius distance. Results: Evaluated TLDs showed the absolute dose delivered to the skin surface using the 3-D printed bolus was 615cGy±6%, with a mean predicted TPS value in the measured area of 617.5±7%. Additionally, planar dose distributions had good qualitative agreement with calculated TPS isodoses. Conclusion: This work demonstrates patient specific 3-D printed HDR brachytherapy applicators for skin cancer treatments are practical and accurate in TPS calculations but additional measurements are needed to verify additional sites and dose at depth.« less

Preparation, anti-biofouling and drag-reduction properties of a biomimetic shark skin surface

PubMed Central

Pu, Xia; Li, Guangji; Huang, Hanlu

2016-01-01

ABSTRACT Shark skin surfaces show non-smoothness characteristics due to the presence of a riblet structure. In this study, biomimetic shark skin was prepared by using the polydimethylsiloxane (PDMS)-embedded elastomeric stamping (PEES) method. Scanning electron microscopy (SEM) was used to examine the surface microstructure and fine structure of shark skin and biomimetic shark skin. To analyse the hydrophobic mechanism of the shark skin surface microstructure, the effect of biomimetic shark skin surface microstructure on surface wettability was evaluated by recording water contact angle. Additionally, protein adhesion experiments and anti-algae adhesion performance testing experiments were used to investigate and evaluate the anti-biofouling properties of the surface microstructure of biomimetic shark skin. The recorded values of the water contact angle of differently microstructured surfaces revealed that specific microstructures have certain effects on surface wettability. The anti-biofouling properties of the biomimetic shark skin surface with microstructures were superior to a smooth surface using the same polymers as substrates. Moreover, the air layer fixed on the surface of the biomimetic shark skin was found to play a key role in their antibiont adhesion property. An experiment into drag reduction was also conducted. Based on the experimental results, the microstructured surface of the prepared biomimetic shark skin played a significant role in reducing drag. The maximum of drag reduction rate is 12.5%, which is higher than the corresponding maximum drag reduction rate of membrane material with a smooth surface. PMID:26941105

Preparation, anti-biofouling and drag-reduction properties of a biomimetic shark skin surface.

PubMed

Pu, Xia; Li, Guangji; Huang, Hanlu

2016-04-15

Shark skin surfaces show non-smoothness characteristics due to the presence of a riblet structure. In this study, biomimetic shark skin was prepared by using the polydimethylsiloxane (PDMS)-embedded elastomeric stamping (PEES) method. Scanning electron microscopy (SEM) was used to examine the surface microstructure and fine structure of shark skin and biomimetic shark skin. To analyse the hydrophobic mechanism of the shark skin surface microstructure, the effect of biomimetic shark skin surface microstructure on surface wettability was evaluated by recording water contact angle. Additionally, protein adhesion experiments and anti-algae adhesion performance testing experiments were used to investigate and evaluate the anti-biofouling properties of the surface microstructure of biomimetic shark skin. The recorded values of the water contact angle of differently microstructured surfaces revealed that specific microstructures have certain effects on surface wettability. The anti-biofouling properties of the biomimetic shark skin surface with microstructures were superior to a smooth surface using the same polymers as substrates. Moreover, the air layer fixed on the surface of the biomimetic shark skin was found to play a key role in their antibiont adhesion property. An experiment into drag reduction was also conducted. Based on the experimental results, the microstructured surface of the prepared biomimetic shark skin played a significant role in reducing drag. The maximum of drag reduction rate is 12.5%, which is higher than the corresponding maximum drag reduction rate of membrane material with a smooth surface. © 2016. Published by The Company of Biologists Ltd.

Optimizing drug-dose alerts using commercial software throughout an integrated health care system.

PubMed

Saiyed, Salim M; Greco, Peter J; Fernandes, Glenn; Kaelber, David C

2017-11-01

All default electronic health record and drug reference database vendor drug-dose alerting recommendations (single dose, daily dose, dose frequency, and dose duration) were silently turned on in inpatient, outpatient, and emergency department areas for pediatric-only and nonpediatric-only populations. Drug-dose alerts were evaluated during a 3-month period. Drug-dose alerts fired on 12% of orders (104 098/834 911). System-level and drug-specific strategies to decrease drug-dose alerts were analyzed. System-level strategies included: (1) turning off all minimum drug-dosing alerts, (2) turning off all incomplete information drug-dosing alerts, (3) increasing the maximum single-dose drug-dose alert threshold to 125%, (4) increasing the daily dose maximum drug-dose alert threshold to 125%, and (5) increasing the dose frequency drug-dose alert threshold to more than 2 doses per day above initial threshold. Drug-specific strategies included changing drug-specific maximum single and maximum daily drug-dose alerting parameters for the top 22 drug categories by alert frequency. System-level approaches decreased alerting to 5% (46 988/834 911) and drug-specific approaches decreased alerts to 3% (25 455/834 911). Drug-dose alerts varied between care settings and patient populations. © The Author 2017. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

10 CFR 835.205 - Determination of compliance for non-uniform exposure of the skin.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 100 cm 2 or more. The non-uniform equivalent dose received during the year shall be averaged over the... irradiated is 10 cm 2 or more, but is less than 100 cm 2. The non-uniform equivalent dose (H) to the... less than 0.1 be used. (3) Area of skin irradiated is less than 10 cm 2. The non-uniform equivalent...

10 CFR 835.205 - Determination of compliance for non-uniform exposure of the skin.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 100 cm 2 or more. The non-uniform equivalent dose received during the year shall be averaged over the... irradiated is 10 cm 2 or more, but is less than 100 cm 2. The non-uniform equivalent dose (H) to the... less than 0.1 be used. (3) Area of skin irradiated is less than 10 cm 2. The non-uniform equivalent...

10 CFR 835.205 - Determination of compliance for non-uniform exposure of the skin.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 100 cm 2 or more. The non-uniform equivalent dose received during the year shall be averaged over the... irradiated is 10 cm 2 or more, but is less than 100 cm 2. The non-uniform equivalent dose (H) to the... less than 0.1 be used. (3) Area of skin irradiated is less than 10 cm 2. The non-uniform equivalent...

10 CFR 835.205 - Determination of compliance for non-uniform exposure of the skin.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 100 cm 2 or more. The non-uniform equivalent dose received during the year shall be averaged over the... irradiated is 10 cm 2 or more, but is less than 100 cm 2. The non-uniform equivalent dose (H) to the... less than 0.1 be used. (3) Area of skin irradiated is less than 10 cm 2. The non-uniform equivalent...

10 CFR 835.205 - Determination of compliance for non-uniform exposure of the skin.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 100 cm 2 or more. The non-uniform equivalent dose received during the year shall be averaged over the... irradiated is 10 cm 2 or more, but is less than 100 cm 2. The non-uniform equivalent dose (H) to the... less than 0.1 be used. (3) Area of skin irradiated is less than 10 cm 2. The non-uniform equivalent...

In situ Biological Dose Mapping Estimates the Radiation Burden Delivered to ‘Spared’ Tissue between Synchrotron X-Ray Microbeam Radiotherapy Tracks

PubMed Central

Rothkamm, Kai; Crosbie, Jeffrey C.; Daley, Frances; Bourne, Sarah; Barber, Paul R.; Vojnovic, Borivoj; Cann, Leonie; Rogers, Peter A. W.

2012-01-01

Microbeam radiation therapy (MRT) using high doses of synchrotron X-rays can destroy tumours in animal models whilst causing little damage to normal tissues. Determining the spatial distribution of radiation doses delivered during MRT at a microscopic scale is a major challenge. Film and semiconductor dosimetry as well as Monte Carlo methods struggle to provide accurate estimates of dose profiles and peak-to-valley dose ratios at the position of the targeted and traversed tissues whose biological responses determine treatment outcome. The purpose of this study was to utilise γ-H2AX immunostaining as a biodosimetric tool that enables in situ biological dose mapping within an irradiated tissue to provide direct biological evidence for the scale of the radiation burden to ‘spared’ tissue regions between MRT tracks. Γ-H2AX analysis allowed microbeams to be traced and DNA damage foci to be quantified in valleys between beams following MRT treatment of fibroblast cultures and murine skin where foci yields per unit dose were approximately five-fold lower than in fibroblast cultures. Foci levels in cells located in valleys were compared with calibration curves using known broadbeam synchrotron X-ray doses to generate spatial dose profiles and calculate peak-to-valley dose ratios of 30–40 for cell cultures and approximately 60 for murine skin, consistent with the range obtained with conventional dosimetry methods. This biological dose mapping approach could find several applications both in optimising MRT or other radiotherapeutic treatments and in estimating localised doses following accidental radiation exposure using skin punch biopsies. PMID:22238667

A two‐point scheme for optimal breast IMRT treatment planning

PubMed Central

2013-01-01

We propose an approach to determining optimal beam weights in breast/chest wall IMRT treatment plans. The goal is to decrease breathing effect and to maximize skin dose if the skin is included in the target or, otherwise, to minimize the skin dose. Two points in the target are utilized to calculate the optimal weights. The optimal plan (i.e., the plan with optimal beam weights) consists of high energy unblocked beams, low energy unblocked beams, and IMRT beams. Six breast and five chest wall cases were retrospectively planned with this scheme in Eclipse, including one breast case where CTV was contoured by the physician. Compared with 3D CRT plans composed of unblocked and field‐in‐field beams, the optimal plans demonstrated comparable or better dose uniformity, homogeneity, and conformity to the target, especially at beam junction when supraclavicular nodes are involved. Compared with nonoptimal plans (i.e., plans with nonoptimized weights), the optimal plans had better dose distributions at shallow depths close to the skin, especially in cases where breathing effect was taken into account. This was verified with experiments using a MapCHECK device attached to a motion simulation table (to mimic motion caused by breathing). PACS number: 87.55 de PMID:24257291

Low-dose radiation modifies skin response to acute gamma-rays and protons.

PubMed

Mao, Xiao Wen; Pecaut, Michael J; Cao, Jeffrey D; Moldovan, Maria; Gridley, Daila S

2013-01-01

The goal of the present study was to obtain pilot data on the effects of protracted low-dose/low-dose-rate (LDR) γ-rays on the skin, both with and without acute gamma or proton irradiation (IR). Six groups of C57BL/6 mice were examined: a) 0 Gy control, b) LDR, c) Gamma, d) LDR+Gamma, e) Proton, and f) LDR+Proton. LDR radiation was delivered to a total dose of 0.01 Gy (0.03 cGy/h), whereas the Gamma and Proton groups received 2 Gy (0.9 Gy/min and 1.0 Gy/min, respectively). Assays were performed 56 days after exposure. Skin samples from all irradiated groups had activated caspase-3, indicative of apoptosis. The significant (p<0.05) increases in immunoreactivity in the Gamma and Proton groups were not present when LDR pre-exposure was included. However, the terminal deoxynucleotidyl transferase dUTP nick-end labeling assay for DNA fragmentation and histological examination of hematoxylin and eosin-stained sections revealed no significant differences among groups, regardless of radiation regimen. The data demonstrate that caspase-3 activation initially triggered by both forms of acute radiation was greatly elevated in the skin nearly two months after whole-body exposure. In addition, LDR γ-ray priming ameliorated this response.

A dose-finding, cross-over study to evaluate the effect of a Nestorone®/Estradiol transdermal gel delivery on ovulation suppression in normal ovulating women.

PubMed

Brache, Vivian; Merkatz, Ruth; Kumar, Narender; Jesam, Cristian; Sussman, Heather; Hoskin, Elena; Roberts, Kevin; Alami, Mohcine; Taylor, Deshawn; Jorge, Aidelis; Croxatto, Horacio; Lorange, Ellen; Mishell, Daniel R; Sitruk-Ware, Regine

2015-10-01

This study aims to determine the lowest effective of three Nestorone (NES)/estradiol (E2) transdermal gel doses to ensure ovulation suppression in 90-95% of cycles. This was a randomized, open-label, three-treatment-period cross-over study to evaluate the effects of NES/E2 transdermal gel on ovulation inhibition, suppression of follicular growth and pharmacokinetic parameters. The doses were low (1.5 mg NES/0.5 mg E2), medium (3.0 mg NES/1.0 mg E2) and high (4.5 mg NES/1.5 mg E2). Participants applied gel daily to a fixed area on the abdomen for 21 consecutive days. They were interviewed regarding their experiences using the gel. Eighteen participants were randomized; 16 completed the study. Median NES C(max) values for low, medium and high dose groups at day 21 were 318.6 pmol/L, 783.0 pmol/L and 1063.8 pmol/L, respectively. Median maximum follicular diameter was higher with the lowest dose with 16.2 mm versus 10.0 and 10.4 mm with the medium and high doses, respectively. Among adherent participants, ovulation was inhibited in all dose groups, except for one participant in the medium dose (6.7%) that had luteal activity and an ultrasound image suggestive of a luteinized unruptured follicle. There were few reports of unscheduled bleeding, with more episodes reported for the lower dose. Adverse events were mild, and no skin irritation was reported from gel application. While all three doses blocked ovulation effectively and were evaluated as safe and acceptable, the medium dose was considered the lowest effective dose based on a more adequate suppression of follicular development. Further development of this novel contraceptive delivering NES and E2 is warranted and has potential for improved safety compared to ethinyl-estradiol-based methods. Copyright © 2015 Elsevier Inc. All rights reserved.

The effect of work system on the hand exposure of workers in 18F-FDG production centres.

PubMed

Wrzesień, Małgorzata

2018-05-07

The production of the 18 F isotope-the marker of deoxyglucose ( 18 F-FDG)-the radiopharmaceutical most commonly used in the oncological diagnostic technique of positron emission tomography, requires a cyclotron device. At present, there are nine facilities working in Poland that are equipped with cyclotrons used for producing the short-lived isotopes. The aim of the paper is to determine the hand exposure of workers employed in the two 18 F-FDG production centres taking in to account the production procedures and work system in those facilities. Measurements, which included all professional workers exposed to ionizing radiation that were employed in two facilities, were performed by using high-sensitivity thermoluminescent detectors during the routine activities of the personnel. The work system used at the production centre has an impact on the level of the recorded doses. Among the production procedures performed by the staff, the highest ionizing radiation doses have been received by the staff during the 18 F-FDG quality control. The maximum estimated annual Hp(0.07) for chemists from the quality control department can exceed the annual skin limit dose (500 mSv). The source of lowest doses on the hands are the cyclotron operating procedure and the 18 F-FDG production, provided that these procedures can't be combined with other production procedures.

Thermal Characteristics of ThermoBrachytherapy Surface Applicators (TBSA) for Treating Chestwall Recurrence

PubMed Central

Arunachalam, K.; Maccarini, P. F.; Craciunescu, O. I.; Schlorff, J. L.; Stauffer, P. R.

2010-01-01

Purpose To study temperature and thermal dose distributions of ThermoBrachytherapy Surface Applicators (TBSA) developed for concurrent or sequential high dose rate (HDR) brachytherapy and microwave hyperthermia treatment of chest wall recurrence and other superficial disease. Methods A steady state thermodynamics model coupled with the fluid dynamics of water bolus and electromagnetic radiation of hyperthermia applicator is used to characterize the temperature distributions achievable with TBSA applicators in an elliptical phantom model of the human torso. Power deposited by 915 MHz conformal microwave array (CMA) applicators is used to assess the specific absorption rate (SAR) distributions of rectangular (500 cm2) and L-shaped (875 cm2) TBSA. The SAR distribution in tissue and fluid flow distribution inside the Dual-Input Dual-Output (DIDO) water bolus are coupled to solve the steady state temperature and thermal dose distributions of rectangular TBSA (R-TBSA) for superficial tumor targets extending 10–15 mm beneath the skin surface. Thermal simulations are carried out for a range of bolus inlet temperature (Tb=38–43°C), water flow rate (Qb=2–4 L/min) and tumor blood perfusion (ωb=2–5 kg/m3/s) to characterize their influence on thermal dosimetry. Results Steady state SAR patterns of R- and L-TBSA demonstrate the ability to produce conformal and localized power deposition inside tumor target sparing surrounding normal tissues and nearby critical organs. Acceptably low variation in tissue surface cooling and surface temperature homogeneity was observed for the new DIDO bolus at 2 L/min water flow rate. Temperature depth profiles and thermal dose volume histograms indicate bolus inlet temperature (Tb) to be the most influential factor on thermal dosimetry. A 42 °C water bolus was observed to be the optimal choice for superficial tumors extending 10–15 mm from the surface even under significant blood perfusion. Lower bolus temperature may be chosen to reduce thermal enhancement ratio (TER) in the most sensitive skin where maximum radiation dose is delivered and to extend thermal enhancement of radiation dose deeper. Conclusion This computational study indicates that well-localized elevation of tumor target temperature to 40–44 °C can be accomplished by large surface-conforming TBSA applicators using appropriate selection of coupling bolus temperature. PMID:20224154

Incidence of malignant skin tumors in 14,140 patients after grenz-ray treatment for benign skin disorders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lindeloef, B.E.; Eklund, G.

1986-12-01

During the years 1949 to 1975, 14,237 patients received therapeutic doses of grenz rays for the treatment of benign skin disorders such as chronic eczema, psoriasis, and warts. The records of 14,140 of these patients (99.3%) formed the basis for an epidemiologic study of the incidence of skin malignancies in this population. Information about the patients, diagnoses, doses, and sites of treatment was obtained from separate records. The follow-up time was 15 years on the average. We searched the Swedish Cancer Registry, Stockholm, for records reporting the incidence of malignant skin tumors in the study population (incidences of basal cellmore » carcinoma are not registered). The expected number of malignancies was calculated on the basis of age- and sex-standardized incidence data from the Swedish Cancer Registry. In 58 patients, a malignant skin tumor was diagnosed more than five years after grenz-ray therapy had first been administered. Nineteen patients had malignant melanomas, and 39 patients had other malignant skin tumors. The expected number of melanomas was 17.8, and that of other malignant skin tumors was 26.9. None of the patients with melanomas, and only eight of the patients with other malignant skin tumors, had received grenz-ray therapy at the site of the tumor. Six of these eight patients had also been exposed to other known carcinogens. Four hundred eighty-one patients had received an accumulated high dose of grenz rays (greater than or equal to 10 000 rad (greater than or equal to 100 Gy)) on one and the same area. No malignancies were found on those areas. Although we cannot exclude grenz-ray therapy as a risk factor in the development of nonmelanoma skin malignancies, this risk, if any, is small, if recommendations for therapy are followed.« less

The regeneration of thermal wound on mice skin (Mus Musculus) after Q-Switch Nd: YAG laser irradiation for cancer therapy candidate

NASA Astrophysics Data System (ADS)

Apsari, R.; Nahdliyatun, E.; Winarni, D.

2017-09-01

The aims of this study are to investigate the regeneration of mice skin tissue (Mus Musculus) irradiated by Q-Switch Nd: YAG laser and morphological change due to Q-Switch Nd: YAG laser irradiation compared to conventional heating (hairdryer). The 2-3 month of twenty-seven mice were used for experimental animals. Mice were incised in the dorsum by the damage effect of laser energy dose (therapeutic dose) of 29.5 J/cm2 with 10 seconds of exposure time, 10 Hz of repetition rate, and 100 pulses of the given single pulse energy. The mice skin tissue was injuried by hairdryer to get burned effect. Mice were divided into three groups, Group I (control) were not treated by anything, Group II were treated by Q-Switch Nd: YAG laser irradiation and sacrificed on (0, 1, 3, 5) days, and Group III were treated by hairdryer then sacrificed on (0, 1, 3, 5) days. Pathology examination showed that the energy of 29,5 J/cm2 dose produced the hole effect (ablation) through the hypodermic layer caused by optical breakdown and collagen coagulation. Thus, the 60 °C temperature of burn showed coagulation necrosis because piknosis discovered in the injured area. The regeneration process showed that the mice skin tissue's ability to regenerate was irradiated by fast laser because of the focus of Q-Switch Nd: YAG laser. It was showed by the scab releases on third day and completely reepithelialization formation on the fifth day. The collagen fibers distribution was same as normal skin tissue on day 5 and so did angiogenesis. Therefore, Q-Switch Nd: YAG laser can be applied for problems of dermatology medical therapies, especially melasma, nevus of ota and tatto therapy. For skin cancer therapy application, energy dose of unregenerated skin tissue is chosen because the death expected effect is permanent.

Lack of correlation between minimal erythema dose and skin phototype in a Colombian scholar population.

PubMed

Sanclemente, Gloria; Zapata, José-F; García, José-J; Gaviria, Angela; Gómez, Luis-F; Barrera, Marcela

2008-11-01

Sun exposure and skin phototype are the most relevant risk factors for skin cancer. Colombia has high levels of ultraviolet radiation during the whole year, therefore, both, high UVI's and outdoor worker's daily activities, in our country are very important risk factors for the development of cutaneous cancer. To date no study has evaluated the usefulness of Fitzpatrick's skin phototype classification in Colombians and its correlation with the minimal erythema dose (MED) and constitutional skin color. Such information is gaining importance in other nations due to the fact that several country's population is becoming more ethnically diverse. To determine the skin phototype, accumulated sun exposure, sun protection behavior, MED and phenotype in a Colombian school population. Last year high school students from the western Antioquia were invited to participate by phone and letter through their respective school directors. A self-questionnaire was handled to each student. A representative sample of the universe was selected for a medical examination by a dermatologist in order to validate the results of the self-questionnaire. The constitutional skin color was determined with the chromameter CR 300 Minolta. The MED was defined as the minimal dose of UVB being able to induce erythema 24 h later. Eight schools of the area agreed to participate in the study, and a total of 911 students (58% girls and 42% boys) filled-out the self-questionnaire. Sun exposure in the majority of individuals was in a level between moderate and very high. Ninety percent of students do not use any sun protection device or cream. Only a 50% of concordance between self-assessed skin phototype vs. medical skin phototype was found, and the highest concordance corresponded to skin phototype II (82%). There was a marked difference in skin photosensitivity of Colombians compared with reports in Caucasians. We observed a marked overlapping in MED's and L* values in phototypes II and III. The Fitzpatrick's classification was not useful in Hispanic populations such as ours. Therefore, a new skin-phototype classification system is required. In our population the constitutional color was a good predictor of the MED but it did not correlate with skin phototype. The self-assessed questionnaire method was not useful to determine skin cancer risk in our population. The majority of this population has light skin phototypes and is highly exposed to solar UV radiation without proper protection.

Comparing a volume based template approach and ultrasound guided freehand approach in multicatheter interstitial accelerated partial breast irradiation.

PubMed

Koh, Vicky Y; Buhari, Shaik A; Tan, Poh Wee; Tan, Yun Inn; Leong, Yuh Fun; Earnest, Arul; Tang, Johann I

2014-06-01

Currently, there are two described methods of catheter insertion for women undergoing multicatheter interstitial accelerated partial breast irradiation (APBI). These are a volume based template approach (template) and a non-template ultrasound guidance freehand approach (non-template). We aim to compare dosimetric endpoints between the template and non-template approach. Twenty patients, who received adjuvant multicatheter interstitial APBI between August 2008 to March 2010 formed the study cohort. Dosimetric planning was based on the RTOG 04-13 protocol. For standardization, the planning target volume evaluation (PTV-Eval) and organs at risk were contoured with the assistance of the attending surgeon. Dosimetric endpoints include D90 of the PTV-Eval, Dose Homogeneity Index (DHI), V200, maximum skin dose (MSD), and maximum chest wall dose (MCD). A median of 18 catheters was used per patient. The dose prescribed was 34 Gy in 10 fractions BID over 5 days. The average breast volume was 846 cm(3) (526-1384) for the entire cohort and there was no difference between the two groups (p = 0.6). Insertion time was significantly longer for the non-template approach (mean 150 minutes) compared to the template approach (mean: 90 minutes) (p = 0.02). The planning time was also significantly longer for the non-template approach (mean: 240 minutes) compared to the template approach (mean: 150 minutes) (p < 0.01). The template approach yielded a higher D90 (mean: 95%) compared to the non-template approach (mean: 92%) (p < 0.01). There were no differences in DHI (p = 0.14), V200 (p = 0.21), MSD (p = 0.7), and MCD (p = 0.8). Compared to the non-template approach, the template approach offered significant shorter insertion and planning times with significantly improved dosimetric PTV-Eval coverage without significantly compromising organs at risk dosimetrically.

Adding Dopamine to Proxymetacaine or Oxybuprocaine Solutions Potentiates and Prolongs the Cutaneous Antinociception in Rats.

PubMed

Chen, Yu-Wen; Chiu, Chong-Chi; Lin, Heng-Teng; Wang, Jhi-Joung; Hung, Ching-Hsia

2018-05-01

We evaluated the interaction of dopamine-proxymetacaine and dopamine- oxybuprocaine antinociception using isobolograms. This experiment uses subcutaneous drug (proxymetacaine, oxybuprocaine, and dopamine) injections under the skin of the rat's back, thus simulating infiltration blocks. The dose-related antinociceptive curves of proxymetacaine and oxybuprocaine alone and in combination with dopamine were constructed, and then the antinociceptive interactions between the local anesthetic and dopamine were analyzed using isobolograms. Subcutaneous proxymetacaine, oxybuprocaine, and dopamine produced a sensory block to local skin pinpricks in a dose-dependent fashion. The rank order of potency was proxymetacaine (0.57 [0.52-0.63] μmol/kg) > oxybuprocaine (1.05 [0.96-1.15] μmol/kg) > dopamine (165 [154-177] μmol/kg; P < .01 for each comparison) based on the 50% effective dose values. On the equianesthetic basis (25% effective dose, 50% effective dose, and 75% effective dose), the nociceptive block duration of proxymetacaine or oxybuprocaine was shorter than that of dopamine (P < .01). Oxybuprocaine or proxymetacaine coinjected with dopamine elicited a synergistic antinociceptive effect and extended the duration of action. Oxybuprocaine and proxymetacaine had a higher potency and provoked a shorter duration of sensory block compared with dopamine. The use of dopamine increased the quality and duration of skin antinociception caused by oxybuprocaine and proxymetacaine.

A methodological approach to a realistic evaluation of skin absorbed doses during manipulation of radioactive sources by means of GAMOS Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Italiano, Antonio; Amato, Ernesto; Auditore, Lucrezia; Baldari, Sergio

2018-05-01

The accurate evaluation of the radiation burden associated with radiation absorbed doses to the skin of the extremities during the manipulation of radioactive sources is a critical issue in operational radiological protection, deserving the most accurate calculation approaches available. Monte Carlo simulation of the radiation transport and interaction is the gold standard for the calculation of dose distributions in complex geometries and in presence of extended spectra of multi-radiation sources. We propose the use of Monte Carlo simulations in GAMOS, in order to accurately estimate the dose to the extremities during manipulation of radioactive sources. We report the results of these simulations for 90Y, 131I, 18F and 111In nuclides in water solutions enclosed in glass or plastic receptacles, such as vials or syringes. Skin equivalent doses at 70 μm of depth and dose-depth profiles are reported for different configurations, highlighting the importance of adopting a realistic geometrical configuration in order to get accurate dosimetric estimations. Due to the easiness of implementation of GAMOS simulations, case-specific geometries and nuclides can be adopted and results can be obtained in less than about ten minutes of computation time with a common workstation.

SU-F-T-361: Dose Enhancement Due to Nanoparticle Addition in Skin Radiotherapy: A Monte Carlo Study Using Kilovoltage Photon Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, X; Chow, J

Purpose: This study investigated the dose enhancement due to addition of nanoparticles with different types and concentrations in skin radiotherapy using kilovoltage photon beams. Methods: An inhomogeneous water phantom (15×15×10 cm{sup 3}) having the skin target layer (0.5–5 mm), added with different concentrations (3–40 mg/ml) of nanoparticles (Au, Pt, I, Ag and Fe{sub 2}O{sub 3}), was irradiated by the 105 and 220 kVp photon beams produced by a Gulmay D3225 Orthovoltage unit. The circular cone of 5-cm diameter and source-to-surface distance of 20 cm were used. Doses in the skin target layer with and without adding the nanoparticles were calculatedmore » using Monte Carlo simulation (the EGSnrc code) through the macroscopic approach. Dose enhancement ratio (DER), defined as the ratio of dose at the target with nanoparticle addition to the dose without addition, was calculated for each type and concentration of nanoparticle in different target thickness. Results: For Au nanoparticle, DER dependence on target thickness for the 220 kVp photon beams was not significant. However, DER for Au nanoparticle was found decreasing with an increase of target thickness when the nanoparticle concentration was increased from 18 to 40 mg/ml using the 105 kVp photon beams. For nanoparticle concentration of 40 mg/ml, DER variation with target thickness was not significant for the 220 kVp photon beams, but DEF was found decreasing with the target thickness when lower energy of photon beam (105 kVp) was used. DEF was found increasing with an increase of nanoparticle concentration. The higher the DEF increasing rate, the higher the atomic number of the nanoparticle except I and Ag for the same target thickness. Conclusion: It is concluded that nanoparticle addition can result in dose enhancement in kilovoltage skin radiotherapy. Moreover, the DER is related to the photon beam energy, target thickness, atomic number and concentration of nanoparticles.« less

SU-G-TeP1-13: Reclined Total Skin Electron Treatment Technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mathew, D; Gerbi, B

Purpose: The purpose is to describe a new reclined technique for treatment of weakened patients that require total skin electron irradiation. Methods: This technique is a modification of a previously published reclined technique differing in that all six patient positions are treated with the gantry angled 60° from vertically down. The patient is located at a treatment distance of 330 cm SSD along the CA of the beam. The 3/8′ thick Lexan beam spoiler is placed 25 cm from the most proximal surface of the patient for all patient treatment positions. To produce a flat, uniform field of ∼190 cmmore » length, the patient was moved longitudinally by an experimentally determined distance. Kodak EDR2 and EBT3 Radiochromic film were placed around the periphery of the phantom, and OSLs were placed every 30° around the phantom periphery to determine output and surface dose uniformity. A piece of Kodak EDR2 was sandwiched between the two slabs of the 30 cm diameter phantom to determine beam penetration. Results: Field uniformity shifting the patient ±75 cm was ±5% over a treatment span of 190 cm. The dose variation around the periphery of the 30 cm diameter phantom varied by <±5% with the maximum values observed at the 0°-300°, 60° locations with the minimum values at the 30°-330°, 60° locations. Results obtained using Kodak EDR2, EBT3 Radiochromic film, and OSLs agreed to within ±5%. Conclusion: This technique provides a very efficient and convenient means by which to treat the entire skin surface of patients incapable of standing for treatment. It provides a treatment field that is both large and uniform enough for adults along with a convenient way to treat four of the six patient treatment positions. The beam spoiler lies to the side of the patient allowing easy access for patient positioning.« less

Helical irradiation of the total skin with dose painting to replace total skin electron beam therapy for therapy-refractory cutaneous CD4+ T-cell lymphoma.

PubMed

Hsieh, Chen-Hsi; Shueng, Pei-Wei; Lin, Shih-Chiang; Tien, Hui-Ju; Shiau, An-Cheng; Chou, Yueh-Hung; Wu, Meng-Hao; Wang, Jen-Yu; Chen, Chi-Kuan; Chen, Yu-Jen

2013-01-01

A 36-year-old woman was diagnosed with a therapy-refractory cutaneous CD4+ T-cell lymphoma, T3N0M0B0, and stage IIB. Helical irradiation of the total skin (HITS) and dose painting techniques, with 30 Gy in 40 fractions interrupted at 20 fractions with one week resting, 4 times per week were prescribed. The diving suit was dressed whole body to increase the superficial dose and using central core complete block (CCCB) technique for reducing the internal organ dose. The mean doses of critical organs of head, chest, and abdomen were 2.1 to 29.9 Gy, 2.9 to 8.1 Gy, and 3.6 to 15.7 Gy, respectively. The mean dose of lesions was 84.0 cGy. The dosage of left side pretreated area was decreased 57%. The tumor regressed progressively without further noduloplaques. During the HITS procedure, most toxicity was grade I except leukocytopenia with grade 3. No epitheliolysis, phlyctenules, tumor lysis syndrome, fever, vomiting, dyspnea, edema of the extremities, or diarrhea occurred during the treatment. HITS with dose painting techniques provides precise dosage delivery with impressive results, sparing critical organs, and offering limited transient and chronic sequelae for previously locally irradiated, therapy-refractory cutaneous T-cell lymphoma.

Estimated UV doses to psoriasis patients during climate therapy at Gran Canaria in March 2006

NASA Astrophysics Data System (ADS)

Nilsen, L. T. N.; Søyland, E.; Krogstad, A. L.

2008-01-01

Psoriasis is a chronic inflammatory disease involving about 2-3% of the Norwegian population. Sun exposure has a positive effect on most psoriasis lesions, but ultraviolet (UV) radiation also causes a direct DNA damage in the skin cells and comprises a carcinogenic potential. UV exposure on the skin causes a local as well as a systemic immune suppressive effect, but the relation between sun exposure and these biological effects is not well known. In March 2006 a study was carried out to investigate possible therapeutic outcome mechanisms in 20 psoriasis patients receiving climate therapy at Gran Canaria. This paper presents estimates of their individual skin UV-doses based on UV measurements and the patients' diaries with information on time spent in the sun. On the first day of exposure the patients received on average 5.1 Standard Erythema Doses (SED: median=4.0 SED, range 2.6-10.3 SED) estimated to the skin. During the 15 days study they received 165.8 SED (range 104.3-210.1 SED). The reduction in PASI score was 72.8% on average, but there was no obvious relation between the improvement and the UV dose. The UV doses were higher than those found from climate therapy studies at other locations. It seems beneficial to use more strict exposure schedules that consider the available UV irradiance, depending on time of the day, time of the year and weather conditions.

High-pressure liquid chromatography and microbiological assay of serum ofloxacin levels in adults receiving intravenous and oral therapy for skin infections.

PubMed Central

Auten, G M; Preheim, L C; Sookpranee, M; Bittner, M J; Sookpranee, T; Vibhagool, A

1991-01-01

Thirty-two adults hospitalized with skin and skin structure infections received intravenous ofloxacin followed by oral ofloxacin. The standard treatment was 400 mg every 12 h. One patient with renal failure received 400 mg every 24 h. Serum ofloxacin levels were measured (1.5 h postdose and 1 h predose) during intravenous (32 patients) and oral (30 patients) therapy. Levels were assayed by high-pressure liquid chromatography (HPLC) and microbiological assay (MBA). Mean levels +/- standard deviation (in micrograms per milliliter) when measured by MBA after intravenous dosing were (postdose versus predose) 6.23 +/- 2.49 versus 2.42 +/- 1.56, and those after oral dosing were 6.17 +/- 3.25 versus 3.49 +/- 2.77. When measured by HPLC, mean levels +/- standard deviation after intravenous dosing were 5.81 +/- 2.08 versus 2.14 +/- 1.26 and those after oral dosing were 5.63 +/- 2.92 versus 3.41 +/- 2.98. There were no significant differences between levels achieved with oral or intravenous dosing when measured by either MBA or HPLC. Levels in serum did not correlate with side effects. The MICs for 50 and 90% of the 40 aerobic pathogens isolated from 21 patients were 0.5 and 2.0 micrograms/ml, respectively. Cure or improvement was achieved in 30 patients. Intravenous and oral administration of ofloxacin yielded similar levels in serum which were safe and effective in the therapy of skin infections in adult patients. PMID:1810189

[The 308 nm Excimer laser for the treatment of psoriasis and inflammatory skin diseases].

PubMed

Fritz, K; Salavastru, C

2018-01-01

Overall, the 308 nm Excimer laser enables not only a more effective and safer UVB therapy than classical UV phototherapy, but also targeted irradiation in higher doses with a lower cumulative load, which results in faster healing of mainly circumscribed skin changes. This also applies to therapy-resistant residual lesions which, despite systemic therapy, did not diminish. Combination therapies usually improve the result and enable the dose of UVB and systemic medication to be reduced. Excimer laser therapy can be used for an increasing number of skin diseases, especially those that respond to phototherapy or photochemotherapy.

Estimation of patient-specific imaging dose for real-time tumour monitoring in lung patients during respiratory-gated radiotherapy

NASA Astrophysics Data System (ADS)

Shiinoki, Takehiro; Onizuka, Ryota; Kawahara, Daisuke; Suzuki, Tatsuhiko; Yuasa, Yuki; Fujimoto, Koya; Uehara, Takuya; Hanazawa, Hideki; Shibuya, Keiko

2018-03-01

Purpose: To quantify the patient-specific imaging dose for real-time tumour monitoring in the lung during respiratory-gated stereotactic body radiotherapy (SBRT) in clinical cases using SyncTraX. Methods and Materials: Ten patients who underwent respiratory-gated SBRT with SyncTraX were enrolled in this study. The imaging procedure for real-time tumour monitoring using SyncTraX was simulated using Monte Carlo. We evaluated the dosimetric effect of a real-time tumour monitoring in a critical organ at risk (OAR) and the planning target volume (PTV) over the course of treatment. The relationship between skin dose and gating efficiency was also investigated. Results: For all patients, the mean D50 to the PTV, ipsilateral lung, liver, heart, spinal cord and skin was 118.3 (21.5–175.9), 31.9 (9.5–75.4), 15.4 (1.1–31.6), 10.1 (1.3–18.1), 25.0 (1.6–101.8), and 3.6 (0.9–7.1) mGy, respectively. The mean D2 was 352.0 (26.5–935.8), 146.4 (27.3–226.7), 90.7 (3.6–255.0), 42.2 (4.8–82.7), 88.0 (15.4–248.5), and 273.5 (98.3–611.6) mGy, respectively. The D2 of the skin dose was found to increase as the gating efficiency decreased. Conclusions: The additional dose to the PTV was at most 1.9% of the prescribed dose over the course of treatment for real-time tumour monitoring. For OARs, we could confirm the high dose region, which may not be susceptible to radiation toxicity. However, to reduce the skin dose from SyncTraX, it is necessary to increase the gating efficiency.

Added aluminum shielding to attenuate back scatter electrons from intra-oral lead shields.

PubMed

Weidlich, G A; Nuesch, C E; Fuery, J J

1996-01-01

An intra-oral lead shield was developed that consists of a lead base with an aluminum layer that is placed upstream of the lead base. Several such shields with various thicknesses of Al layers were manufactured and quantitatively evaluated in 6 MeV and 12 MeV electron radiation by Thermoluminescent dosimetry (TLD) measurements. The clinical relevance was established by using a 5 cm backscatter block down-stream of the lead shield to simulate anatomical structures of the head and a 0.5 cm superflab bolus upstream of the Al layers of the shield to simulate the patient's lip or cheek. The TLDs were placed between the Al layers of the shield and the superflab to determine the intra-oral skin dose. TLD exposure results revealed that 59.8% of the skin dose at 6 MeV and 45.1% of the skin dose at 12 MeV is due to backscattered electrons. Introduction of a 3.0 mm thick Al layer reduces the backscatter contribution to 13.5% of the back scatter dose at 6 MeV and 56.3% of the back scatter dose at 12 MeV electron radiation.

UVB-induced gene expression in the skin of Xiphophorus maculatus Jp 163 B☆

PubMed Central

Yang, Kuan; Boswell, Mikki; Walter, Dylan J.; Downs, Kevin P.; Gaston-Pravia, Kimberly; Garcia, Tzintzuni; Shen, Yingjia; Mitchell, David L.; Walter, Ronald B.

2014-01-01

Xiphophorus fish and interspecies hybrids represent long-standing models to study the genetics underlying spontaneous and induced tumorigenesis. The recent release of the Xiphophorus maculatus genome sequence will allow global genetic regulation studies of genes involved in the inherited susceptibility to UVB-induced melanoma within select backcross hybrids. As a first step toward this goal, we report results of an RNA-Seq approach to identify genes and pathways showing modulated transcription within the skin of X. maculatus Jp 163 B upon UVB exposure. X. maculatus Jp 163 B were exposed to various doses of UVB followed by RNA-Seq analysis at each dose to investigate overall gene expression in each sample. A total of 357 genes with a minimum expression change of 4-fold (p-adj < 0.05) were identified as responsive to UVB. The molecular genetic response of Xiphophorus skin to UVB exposure permitted assessment of; (1) the basal expression level of each transcript for each skin sample, (2) the changes in expression levels for each gene in the transcriptome upon exposure to increasing doses of UVB, and (3) clusters of genes that exhibit similar patterns of change in expression upon UVB exposure. These data provide a foundation for understanding the molecular genetic response of fish skin to UVB exposure. PMID:24556253

Development of a guinea pig cutaneous radiation injury model using low penetrating X-rays.

PubMed

Rodgers, Kathleen E; Tan, Alick; Kim, Lila; Espinoza, Theresa; Meeks, Christopher; Johnston, William; Maulhardt, Holly; Donald, Melissa; Hill, Colin; diZerega, Gere S

2016-08-01

A guinea pig skin model was developed to determine the dose-dependent response to soft X-ray radiation into the dermis. X-ray exposure (50 kVp) was defined to a 4.0 × 4.0 cm area on the lateral surface of a guinea pig using lead shielding. Guinea pigs were exposed to a single fraction of X-ray irradiation ranging from 25-79 Gy via an XRAD320ix Biological Irradiator with the collimator removed. Gross skin changes were measured using clinical assessments defined by the Kumar scale. Skin contracture was assessed, as well as histological evaluations. Loss of dermal integrity was shown after a single dose of soft X-ray radiation at or above 32 Gy with the central 2.0 × 2.0 cm of the exposed site being the most affected. Hallmarks of the skin injury included moist desquamation, ulceration and wound contracture, as well as alterations in epithelium, dermis, muscle and adipose. Changes in the skin were time- and radiation dose-dependent. Full-thickness injury occurred without animal mortality or gross changes in the underlying organs. The guinea pig is an appropriate small animal model for the short-term screening of countermeasures for cutaneous radiation injury (CRI).

Reduced radiation dose for elective nodal irradiation in node-negative anal cancer: back to the roots?

PubMed

Henkenberens, Christoph; Meinecke, Daniela; Michael, Stoll; Bremer, Michael; Christiansen, Hans

2015-11-01

Chemoradiation (CRT) is the standard of care in patients with node-positive (cN+) and node-negative (cN0) anal cancer. Depending on the tumor size (T-stage), total doses of 50-60 Gray (Gy) in daily fractions of 1.8-2.0 Gy are usually applied to the tumor site. Inguinal and iliac lymph nodes usually receive a dose of ≥ 45 Gy. Since 2010, our policy has been to apply a reduced total dose of 39.6 Gy to uninvolved nodal regions. This paper provides preliminary results of the efficacy and safety of this protocol. Overall, 30 patients with histologically confirmed and node-negative anal cancer were treated in our department from 2009-2014 with definitive CRT. Histology all cases showed squamous cell carcinoma. A total dose of 39.6 Gy [single dose (SD) 1.8 Gy] was delivered to the iliac/inguinal lymph nodes. The area of the primary tumor received 50-59.4 Gy, depending on the T-stage. In parallel with the irradiation, 5-fluorouracil (5-FU) at a dose of 1000 mg/m(2) was administered by continuous intravenous infusion over 24 h on days 1-4 and 29-32, and mitomycin C (MMC) at a dose of 10 mg/m(2) (maximum absolute dose 14 mg) was administered on days 1 and 29. The distribution of the tumor stages was as follows: T1, n = 8; T2, n = 17; T3 n = 3. Overall survival (OS), local control (LC) of the lymph nodes, colostomy-free survival (CFS), and acute and chronic toxicities were assessed. The median follow-up was 27.3 months (range 2.7-57.4 months). Three patients (10.0 %) died, 2 of cardiopulmonary diseases and one of liver failure, yielding a 3-year OS of 90.0 %. Two patients (6.7 %) relapsed early and received salvage colostomies, yielding a 3-year CFS of 93.3 %. No lymph node relapses were observed, giving a lymph node LC of 100 %. According to the Common Terminology Criteria for Adverse Events Version 4.0 (CTCAE V. 4.0), there were no grade IV gastrointestinal or genitourinary acute toxicities. Seven patients showed acute grade III perineal skin toxicity. Acute grade III groin skin toxicity was not observed. Reducing the total irradiation dose to uninvolved nodal regions to 39.6 Gy in chemoradiation protocols for anal carcinoma was safe and effective, and a prospective evaluation in future clinical trials is warranted.

Clinical application of 3D-printed-step-bolus in post-total-mastectomy electron conformal therapy.

PubMed

Park, Kwangwoo; Park, Sungjin; Jeon, Mi-Jin; Choi, Jinhyun; Kim, Jun Won; Cho, Yoon Jin; Jang, Won-Seok; Keum, Yo Sup; Lee, Ik Jae

2017-04-11

The 3D-printed boluses were used during the radiation therapy of the chest wall in six patients with breast cancer after modified radical mastectomy (MRM). We measured the in-vivo skin doses while both conventional and 3D-printed boluses were placed on the chest wall and compared the mean doses delivered to the ipsilateral lung and the heart. The homogeneity and conformity of the dose distribution in the chest wall for both types of boluses were also evaluated. The uniformity index on the chest skin was improved when the 3D-printed boluses were used, with the overall average skin dose being closer to the prescribed one in the former case (-0.47% versus -4.43%). On comparing the dose-volume histogram (DVH), it was found that the 3D-printed boluses resulted in a reduction in the mean dose to the ipsilateral lung by up to 20%. The precision of dose delivery was improved by 3% with the 3D-printed boluses; in contrast, the conventional step bolus resulted in a precision level of 5%. In conclusion, the use of the 3D-printed boluses resulted in better dose homogeneity and conformity to the chest wall as well as the sparing of the normal organs, especially the lung. This suggested that their routine use on the chest wall as a therapeutic approach during post-mastectomy radiation therapy offers numerous advantages over conventional step boluses.

Clinical application of 3D-printed-step-bolus in post-total-mastectomy electron conformal therapy

PubMed Central

Park, Kwangwoo; Park, Sungjin; Jeon, Mi-Jin; Choi, Jinhyun; Kim, Jun Won; Cho, Yoon Jin; Jang, Won-Seok; Keum, Yo Sup; Lee, Ik Jae

2017-01-01

The 3D-printed boluses were used during the radiation therapy of the chest wall in six patients with breast cancer after modified radical mastectomy (MRM). We measured the in-vivo skin doses while both conventional and 3D-printed boluses were placed on the chest wall and compared the mean doses delivered to the ipsilateral lung and the heart. The homogeneity and conformity of the dose distribution in the chest wall for both types of boluses were also evaluated. The uniformity index on the chest skin was improved when the 3D-printed boluses were used, with the overall average skin dose being closer to the prescribed one in the former case (-0.47% versus -4.43%). On comparing the dose-volume histogram (DVH), it was found that the 3D-printed boluses resulted in a reduction in the mean dose to the ipsilateral lung by up to 20%. The precision of dose delivery was improved by 3% with the 3D-printed boluses; in contrast, the conventional step bolus resulted in a precision level of 5%. In conclusion, the use of the 3D-printed boluses resulted in better dose homogeneity and conformity to the chest wall as well as the sparing of the normal organs, especially the lung. This suggested that their routine use on the chest wall as a therapeutic approach during post-mastectomy radiation therapy offers numerous advantages over conventional step boluses. PMID:27784001

Evaluation of drug and sunscreen permeation via skin irradiated with UVA and UVB: comparisons of normal skin and chronologically aged skin.

PubMed

Hung, Chi-Feng; Fang, Chia-Lang; Al-Suwayeh, Saleh A; Yang, Shih-Yung; Fang, Jia-You

2012-12-01

Ultraviolet (UV) exposure is the predominant cause of skin aging. A systematic evaluation of drug skin permeation via photoaged skin is lacking. The aim of this work was to investigate whether UVA and UVB affect absorption by the skin of drugs and sunscreens, including tetracycline, quercetin, and oxybenzone. The dorsal skin of nude mice was subjected to UVA (24 and 39 J/cm(2)) or UVB (150, 200, and 250 mJ/cm(2)) irradiation. Levels of skin water loss, erythema, and sebum were evaluated, and histological examinations of COX-2 and claudin-1 expressions were carried out. Permeation of the permeants into and through the skin was determined in vitro using a Franz cell. In vivo skin uptake was also evaluated. Senescent skin (24 weeks old) was used for comparison. Wrinkling and scaling were significant signs of skin treated with UVA and UVB, respectively. The level of claudin-1, an indicator of tight junctions (TJs), was reduced by UVA and UVB irradiation. UVA enhanced tetracycline and quercetin skin deposition by 11- and 2-fold, respectively. A similar enhancement was shown for flux profiles. Surprisingly, a lower UVA dose revealed greater enhancement compared to the higher dose. The skin deposition and flux of tetracycline both decreased with UVB exposure. UVB also significantly reduced quercetin flux. The skin absorption behavior of chronologically aged skin approximated that of the UVA group, with photoaged skin showing higher enhancement. UV generally exhibited a negligible effect on modulating oxybenzone permeation. Skin disruption produced by UV does not necessarily result in enhanced skin absorption. It depends on the UV wavelength, irradiated energy, and physicochemical properties of the permeant. To the best of our knowledge, this is the first report establishing drug permeation profiles for UV-irradiated skin. Copyright © 2012 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

Radioactivity of peat mud used in therapy.

PubMed

Karpińska, Maria; Mnich, Krystian; Kapała, Jacek; Bielawska, Agnieszka; Kulesza, Grzegorz; Mnich, Stanisław

2016-02-01

The aim of the study was to determine the contents of natural and artificial isotopes in peat mud and to estimate the radiation dose absorbed via skin in patients during standard peat mud treatment. The analysis included 37 samples collected from 8 spas in Poland. The measurements of isotope concentration activity were conducted with the use of gamma spectrometry methods. The skin dose in a standard peat mud bath therapy is approximately 300 nSv. The effective dose of such therapy is considered to be 22 nSv. The doses absorbed during peat mud therapy are 5 orders of magnitude lower than effective annual dose absorbed from the natural radiation background by a statistical Pole (3.5 mSv). Neither therapeutic nor harmful effect is probable in case of such a small dose of ionising radiation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Dosimetric study and in-vivo dose verification for conformal avoidance treatment of anal adenocarcinoma using helical tomotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han Chunhui; Chen Yijen; Liu An

2007-04-01

This study evaluated the efficacy of using helical tomotherapy for conformal avoidance treatment of anal adenocarcinoma. We retrospectively generated step-and-shoot intensity-modulated radiotherapy (sIMRT) plans and helical tomotherapy plans for two anal cancer patients, one male and one female, who were treated by the sIMRT technique. Dose parameters for the planning target volume (PTV) and the organs-at-risk (OARs) were compared between the sIMRT and the helical tomotherapy plans. The helical tomotherapy plans showed better dose homogeneity in the PTV, better dose conformity around the PTV, and, therefore, better sparing of nearby OARs compared with the sIMRT plans. In-vivo skin dose measurementsmore » were performed during conformal avoidance helical tomotherapy treatment of an anal cancer patient to verify adequate delivery of skin dose and sparing of OARs.« less

Skin entrance dose with and without lead apron in digital panoramic radiography for selected sensitive body regions.

PubMed

Schulze, Ralf Kurt Willy; Cremers, Catrin; Karle, Heiko; de Las Heras Gala, Hugo

2017-05-01

The aim of this study was to compare the dose at skin level at five significant anatomical regions for panoramic radiography devices with and without lead apron by means of a highly sensitive dosimeter. A female RANDO-phantom was exposed in five different digital panoramic radiography systems, and the dose at skin level was assessed tenfold for each measurement region by means of a highly sensitive solid-state-dosimeter. The five measurement regions selected were the thyroid, both female breasts, the gonads, and a central region in the back of the phantom. For each panoramic machine, the measurements were performed in two modes: with and without a commercial lead apron specifically designed for panoramic radiography. Reproducibility of the measurements was expressed by absolute differences and the coefficient of variation. Values between shielded and unshielded doses were pooled for each region and compared by means of the paired Wilcoxon tests (p ≤ 0.05). Reproducibility as represented by the mean CV was 22 ± 52 % (median 2.3 %) with larger variations for small dose values. Doses at skin level ranged between 0.00 μGy at the gonads and 85.39 μGy at the unshielded thyroid (mean ± SD 15 ± 24 μGy). Except for the gonads, the dose in all the other regions was significantly lower (p < 0.001) when a lead apron was applied. Unshielded doses were between 1.02-fold (thyroid) and 112-fold (at the right breast) higher than those with lead apron shielding (mean: 14-fold ± 18-fold). Although the doses were entirely very low, we observed a significant increase in dose in the radiation-sensitive female breast region when no lead apron was used. Future discussions on shielding requirements for panoramic radiography should focus on these differences in the light of the linear non-threshold (LNT) theory which is generally adopted in medical imaging.

Evaluation of skin firmness by the DynaSKIN, a novel non-contact compression device, and its use in revealing the efficacy of a skincare regimen featuring a novel anti-ageing ingredient, acetyl aspartic acid.

PubMed

Kearney, E M; Messaraa, C; Grennan, G; Koeller, G; Mavon, A; Merinville, E

2017-05-01

One of the key strategies for anti-ageing in the cosmetics industry today is to target the structural changes responsible for ptosis of the skin, given its impact on age perception. Several objective and non-invasive methods are available to characterise the biomechanical properties of the skin, which are operator-dependent, involving skin contact and providing single-dimensional numerical descriptions of skin behaviour. The research introduces the DynaSKIN, a device using non-contact mechanical pressure in combination with fringe projection to quantify and visualise the skin response in 3-dimensions. We examine the age correlation of the measurements, how they compare with the Cutometer ® , and measure skin dynamics following application of a skincare regimen containing established anti-ageing ingredients. DynaSKIN and Cutometer ® measurements were made on the cheek of 80 Caucasian women (18-64 years). DynaSKIN volume, mean depth and maximum depth parameters were correlated with age and 15 Cutometer ® parameters. Subsequently, the firming efficacy of a skincare regimen featuring acetyl aspartic acid (AAA) and a peptide complex was examined in a cohort of 41 volunteers. DynaSKIN volume, mean depth and maximum depth parameters correlate with age and the Cutometer ® parameters that are associated with the skin relaxation phase (R1, R2, R4, R5, R7 and F3). Furthermore, the DynaSKIN captured significant improvements in skin firmness delivered by the skincare regimen. The DynaSKIN is a novel device capable of capturing skin biomechanics at a high level of specificity and successfully detected the firming properties of a skincare regimen. Its independent measuring principle, consumer relevance and skin firmness 3D visualisation capabilities bring objectivity and novelty to product efficacy substantiation evaluation. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Objective assessment in digital images of skin erythema caused by radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsubara, H., E-mail: matubara@nirs.go.jp; Matsufuji, N.; Tsuji, H.

Purpose: Skin toxicity caused by radiotherapy has been visually classified into discrete grades. The present study proposes an objective and continuous assessment method of skin erythema in digital images taken under arbitrary lighting conditions, which is the case for most clinical environments. The purpose of this paper is to show the feasibility of the proposed method. Methods: Clinical data were gathered from six patients who received carbon beam therapy for lung cancer. Skin condition was recorded using an ordinary compact digital camera under unfixed lighting conditions; a laser Doppler flowmeter was used to measure blood flow in the skin. Themore » photos and measurements were taken at 3 h, 30, and 90 days after irradiation. Images were decomposed into hemoglobin and melanin colors using independent component analysis. Pixel values in hemoglobin color images were compared with skin dose and skin blood flow. The uncertainty of the practical photographic method was also studied in nonclinical experiments. Results: The clinical data showed good linearity between skin dose, skin blood flow, and pixel value in the hemoglobin color images; their correlation coefficients were larger than 0.7. It was deduced from the nonclinical that the uncertainty due to the proposed method with photography was 15%; such an uncertainty was not critical for assessment of skin erythema in practical use. Conclusions: Feasibility of the proposed method for assessment of skin erythema using digital images was demonstrated. The numerical relationship obtained helped to predict skin erythema by artificial processing of skin images. Although the proposed method using photographs taken under unfixed lighting conditions increased the uncertainty of skin information in the images, it was shown to be powerful for the assessment of skin conditions because of its flexibility and adaptability.« less

False-Positive Tuberculin Skin Test Results Among Low-Risk Healthcare Workers Following Implementation of Fifty-Dose Vials of Purified Protein Derivative.

PubMed

Collins, Jeffrey M; Hunter, Mary; Gordon, Wanda; Kempker, Russell R; Blumberg, Henry M; Ray, Susan M

2018-06-01

Following large declines in tuberculosis transmission the United States, large-scale screening programs targeting low-risk healthcare workers are increasingly a source of false-positive results. We report a large cluster of presumed false-positive tuberculin skin test results in healthcare workers following a change to 50-dose vials of Tubersol tuberculin.Infect Control Hosp Epidemiol 2018;39:750-752.

Verification of screening level for decontamination implemented after Fukushima nuclear accident

PubMed Central

Ogino, Haruyuki; Ichiji, Takeshi; Hattori, Takatoshi

2012-01-01

The screening level for decontamination that has been applied for the surface of the human body and contaminated handled objects after the Fukushima nuclear accident was verified by assessing the doses that arise from external irradiation, ingestion, inhalation and skin contamination. The result shows that the annual effective dose that arises from handled objects contaminated with the screening level for decontamination (i.e. 100 000 counts per minute) is <1 mSv y−1, which can be considered as the intervention exemption level in accordance with the International Commission on Radiological Protection recommendations. Furthermore, the screening level is also found to protect the skin from the incidence of a deterministic effect because the absorbed dose of the skin that arises from direct deposition on the surface of the human body is calculated to be lower than the threshold of the deterministic effect assuming a practical exposure duration. PMID:22228683

Assessment of peak skin dose in interventional cardiology: A comparison between Gafchromic film and dosimetric software em.dose.

PubMed

Greffier, J; Van Ngoc Ty, C; Bonniaud, G; Moliner, G; Ledermann, B; Schmutz, L; Cornillet, L; Cayla, G; Beregi, J P; Pereira, F

2017-06-01

To compare the use of a dose mapping software to Gafchromic film measurement for a simplified peak skin dose (PSD) estimation in interventional cardiology procedure. The study was conducted on a total of 40 cardiac procedures (20 complex coronary angioplasty of chronic total occlusion (CTO) and 20 coronary angiography and coronary angioplasty (CA-PTCA)) conducted between January 2014 to December 2015. PSD measurement (PSD Film ) was obtained by placing XR-RV3 Gafchromic under the patient's back for each procedure. PSD (PSD em.dose ) was computed with the software em.dose©. The calculation was performed on the dose metrics collected from the private dose report of each procedure. Two calculation methods (method A: fluoroscopic kerma equally spread on cine acquisition and B: fluoroscopic kerma is added to one air Kerma cine acquisition that contributes to the PSD) were used to calculate the fluoroscopic dose contribution as fluoroscopic data were not recorded in our interventional room. Statistical analyses were carried out to compare PSD Film and PSD em.dose . The PSD Film median (1st quartile; 3rd quartile) was 0.251(0.190;0.336)Gy for CA-PTCA and 1.453(0.767;2.011)Gy for CTO. For method-A, the PSD em.dose was 0.248(0.182;0.369)Gy for CA-PTCA and 1.601(0.892;2.178)Gy for CTO, and 0.267(0.223;0.446)Gy and 1.75 (0.912;2.584)Gy for method-B, respectively. For the two methods, the correlation between PSD Film and PSD em.dose was strong. For all cardiology procedures investigated, the mean deviation between PSD Film and PSD em.dose was 3.4±21.1% for method-A and 17.3%±23.9% for method-B. The dose mapping software is convenient to calculate peak skin dose in interventional cardiology. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Mechanism underlying the effect of combined therapy using glucosamine and low-dose cyclosporine A on the development of atopic dermatitis-like skin lesions in NC/Nga mice.

PubMed

Kim, Chang-Hyun; Choi, Yun-Seok; Cheong, Kyung Ah; Lee, Ai-Young

2013-02-01

Combination therapy is often used in the treatment of atopic dermatitis (AD) to improve clinical efficacy or to spare the dose of each drug. Cyclosporine A (CsA) is a calcineurin inhibitor that was developed for the treatment of AD. Glucosamine (Glu) is a potent immunosuppressant that inhibits Th2-mediated immunity. We previously reported that Glu has an ameliorative effect on the development of the pathology in NC/Nga mice. The aims of our study were to investigate the therapeutic efficacy of combination of Glu and low-dose CsA in dermatophagoides farina (Df)-induced AD-like skin lesions in NC/Nga mice and to determine the underlying therapeutic mechanisms. The Df-induced NC/Nga mice with a clinical score of 7 were used for treatment with Glu (500mg/kg) alone, low-dose CsA (2, 5, and 10mg/kg) or in combination. The clinical scores were reduced significantly by the combination treatment with Glu and low-dose CsA. The suppression of dermatitis by combined therapy was accompanied by decrease in the plasma level of IgE and in the splenic level of IL-4, IL-5, IL-13, TARC and eotaxin. Histological analysis of the skin also revealed that combination treatment significantly reduced the inflammatory cellular infiltrate, including mast cells and eosinophils. Particularly, immunological evaluation reveals an increase of CD4(+)CD25(+) Treg cells in the combined treatment. The induction of TSLP, which leads to systemic Th2 response, was reduced in the skin on combination treatment. The protein expression of filaggrin and involucrin was recovered by combination treatment in the skin lesions, whereas the protein expression of keratin-10 and keratin-14 decreased in the combination treatment. Collectively, our findings suggest that combination treatment of Glu and low-dose CsA leads to the therapeutic effects in Df-induced AD-like skin lesion in NC/Nga mice through inhibition of IgE, inflammatory cellular infiltrate, and recovery of skin barrier function via a mechanism that may inhibition of Th2-mediated immune responses, in part, increment of CD4(+)CD25(+) Treg cells. These results suggest that this combined immunosuppressive treatment may provide important implications for the design of therapeutic strategies aimed at AD treatment. Copyright © 2013 Elsevier B.V. All rights reserved.

Verification of calculated skin doses in postmastectomy helical tomotherapy.

PubMed

Ito, Shima; Parker, Brent C; Levine, Renee; Sanders, Mary Ella; Fontenot, Jonas; Gibbons, John; Hogstrom, Kenneth

2011-10-01

To verify the accuracy of calculated skin doses in helical tomotherapy for postmastectomy radiation therapy (PMRT). In vivo thermoluminescent dosimeters (TLDs) were used to measure the skin dose at multiple points in each of 14 patients throughout the course of treatment on a TomoTherapy Hi·Art II system, for a total of 420 TLD measurements. Five patients were evaluated near the location of the mastectomy scar, whereas 9 patients were evaluated throughout the treatment volume. The measured dose at each location was compared with calculations from the treatment planning system. The mean difference and standard error of the mean difference between measurement and calculation for the scar measurements was -1.8% ± 0.2% (standard deviation [SD], 4.3%; range, -11.1% to 10.6%). The mean difference and standard error of the mean difference between measurement and calculation for measurements throughout the treatment volume was -3.0% ± 0.4% (SD, 4.7%; range, -18.4% to 12.6%). The mean difference and standard error of the mean difference between measurement and calculation for all measurements was -2.1% ± 0.2% (standard deviation, 4.5%: range, -18.4% to 12.6%). The mean difference between measured and calculated TLD doses was statistically significant at two standard deviations of the mean, but was not clinically significant (i.e., was <5%). However, 23% of the measured TLD doses differed from the calculated TLD doses by more than 5%. The mean of the measured TLD doses agreed with TomoTherapy calculated TLD doses within our clinical criterion of 5%. Copyright © 2011 Elsevier Inc. All rights reserved.

Verification of Calculated Skin Doses in Postmastectomy Helical Tomotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ito, Shima; Parker, Brent C., E-mail: bcparker@marybird.com; Mary Bird Perkins Cancer Center, Baton Rouge, LA

2011-10-01

Purpose: To verify the accuracy of calculated skin doses in helical tomotherapy for postmastectomy radiation therapy (PMRT). Methods and Materials: In vivo thermoluminescent dosimeters (TLDs) were used to measure the skin dose at multiple points in each of 14 patients throughout the course of treatment on a TomoTherapy Hi.Art II system, for a total of 420 TLD measurements. Five patients were evaluated near the location of the mastectomy scar, whereas 9 patients were evaluated throughout the treatment volume. The measured dose at each location was compared with calculations from the treatment planning system. Results: The mean difference and standard errormore » of the mean difference between measurement and calculation for the scar measurements was -1.8% {+-} 0.2% (standard deviation [SD], 4.3%; range, -11.1% to 10.6%). The mean difference and standard error of the mean difference between measurement and calculation for measurements throughout the treatment volume was -3.0% {+-} 0.4% (SD, 4.7%; range, -18.4% to 12.6%). The mean difference and standard error of the mean difference between measurement and calculation for all measurements was -2.1% {+-} 0.2% (standard deviation, 4.5%: range, -18.4% to 12.6%). The mean difference between measured and calculated TLD doses was statistically significant at two standard deviations of the mean, but was not clinically significant (i.e., was <5%). However, 23% of the measured TLD doses differed from the calculated TLD doses by more than 5%. Conclusions: The mean of the measured TLD doses agreed with TomoTherapy calculated TLD doses within our clinical criterion of 5%.« less

DOSE-RESPONSE STUDIES OF SODIUM ARSENITE IN THE SKIN OF K6/ODC TRANSGENIC MOUSE

EPA Science Inventory

It has previously been observed that chronic exposure to inorganic arsenic and/or its metabolites increase(s) tumor frequency in the skin of K6/ODC transgenic mice. To identify potential biomarkers and modes of action for this skin tumorigenicity, gene expression profiles w...

SU-E-T-193: FMEA Severity Scores - Do We Really Know?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khan, A; Robertson, JD; Narra, V

2014-06-01

Purpose: Mycosis fungoides is a common form of cutaneous T-cell lymphoma which generally affects the skin. A typical course of treatment may include fractionated total skin electron beam therapy. Given the difficulties in uniformly irradiating some regions of the body and the need for frequent visits within the context of a fractionated protocol, this study investigated the feasibility of delivering the dose using form-fitting cloth which contained phosphorous-32 as a source for beta particle irradiation. Methods: A piece of fabric (0.97 g) consisting of a blend of spandex and flame retardant material impregnated with phosphorus-31 (2000 ppm) was bombarded withmore » neutrons to produce phosphorus-32. The cloth was then laid flat and a stack of radiochromic film placed on top. Sheets of film and tissue equivalent plastic were layered to form a stack measuring a total of 1 cm thickness and remained sandwiched for 77.3 hr. Results: The initial activity of the activated cloth was 44 μCi of P-32. The absorbed dose was uniform within planes parallel to the cloth and exponentially dependent on depth, delivering 560cGy at 0.3mm and falling to 20cGy at 3mm. Conclusion: The total dose prescribed for a typical course of TSET for mycosis fungoides is 36Gy delivered over 9 weeks and is expected to treat to at least 5mm depth. Therefore, the P-32 impregnated cloth may not be clinically indicated to treat this disease given the unfavorable depth-dose characteristics. However, a major advantage of using form-fitting cloth is the uniformity with which the dose could be delivered over the skin in areas which are not flat. Increasing the distance between cloth and skin could improve the depth-dose characteristics.« less

Quantitative Proteomic Profiling of Low Dose Ionizing Radiation Effects in a Human Skin Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hengel, Shawna; Aldrich, Joshua T.; Waters, Katrina M.

2014-07-29

To assess molecular responses to low doses of radiation that may be encountered during medical diagnostic procedures, nuclear accidents, or terrorist acts, a quantitative global proteomic approach was used to identify protein alterations in a reconstituted human skin tissue treated with 10 cGy of ionizing radiation. Subcellular fractionation was employed to remove highly abundant structural proteins and provide insight on radiation induced alterations in protein abundance and localization. In addition, peptides were post-fractionated using high resolution 2-dimensional liquid chromatography to increase the dynamic range of detection of protein abundance and translocation changes. Quantitative data was obtained by labeling peptides withmore » 8-plex isobaric iTRAQ tags. A total of 207 proteins were detected with statistically significant alterations in abundance and/or subcellular localization compared to sham irradiated tissues. Bioinformatics analysis of the data indicated that the top canonical pathways affected by low dose radiation are related to cellular metabolism. Among the proteins showing alterations in abundance, localization and proteolytic processing was the skin barrier protein filaggrin which is consistent with our previous observation that ionizing radiation alters profilaggrin processing with potential effects on skin barrier functions. In addition, a large number of proteases and protease regulators were affected by low dose radiation exposure indicating that altered proteolytic activity may be a hallmark of low dose radiation exposure. While several studies have demonstrated altered transcriptional regulation occurs following low dose radiation exposures, the data presented here indicates post-transcriptional regulation of protein abundance, localization, and proteolytic processing play an important role in regulating radiation responses in complex human tissues.« less

Decreasing Skin Graft Contraction through Topical Wound Bed Preparation with Anti-Inflammatory Agents

DTIC Science & Technology

2015-10-01

This proposal aims to identify topically applied anti-inflammatory drugs that will reduce recipient site inflammation and skin graft contraction. We...hypothesize that the elevated and prolonged inflammatory state of the recipient wound bed is a causative factor in the development of skin graft contraction...Using a porcine model of skin graft contraction, we will screen for anti-inflammatory agents (dose, schedule of administration, drug class

Radiation Doses to Skin from Dermal Contamination

DTIC Science & Technology

2010-10-01

included studies of deposition of particles on skin, hair or clothing of human volunteers and on samples of rat skin or other materials (filter paper ...Particle size probably is the most important parameter that affects interception and retention on skin. In a theoretical part of their paper , Asset and...about 20% of the particles of either diameter (standard deviation about 11%) from such surfaces as cotton, paper , wood, or plastic. The efficiency

Dose response evaluation of gene expression profiles in the skin of K6/ODC mice exposed to sodium arsenite.

PubMed

Ahlborn, Gene J; Nelson, Gail M; Ward, William O; Knapp, Geremy; Allen, James W; Ouyang, Ming; Roop, Barbara C; Chen, Yan; O'Brien, Thomas; Kitchin, Kirk T; Delker, Don A

2008-03-15

Chronic drinking water exposure to inorganic arsenic and its metabolites increases tumor frequency in the skin of K6/ODC transgenic mice. To identify potential biomarkers and modes of action for this skin tumorigenicity, we characterized gene expression profiles from analysis of K6/ODC mice administered 0, 0.05, 0.25, 1.0 and 10 ppm sodium arsenite in their drinking water for 4 weeks. Following exposure, total RNA was isolated from mouse skin and processed to biotin-labeled cRNA for microarray analyses. Skin gene expression was analyzed with Affymetrix Mouse Genome 430A 2.0 GeneChips, and pathway analysis was conducted with DAVID (NIH), Ingenuity Systems and MetaCore's GeneGo. Differential expression of several key genes was verified through qPCR. Only the highest dose (10 ppm) resulted in significantly altered KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways, including MAPK, regulation of actin cytoskeleton, Wnt, Jak-Stat, Tight junction, Toll-like, phosphatidylinositol and insulin signaling pathways. Approximately 20 genes exhibited a dose response, including several genes known to be associated with carcinogenesis or tumor progression including cyclin D1, CLIC4, Ephrin A1, STAT3 and DNA methyltransferase 3a. Although transcription changes in all identified genes have not previously been linked to arsenic carcinogenesis, their association with carcinogenesis in other systems suggests that these genes may play a role in the early stages of arsenic-induced skin carcinogenesis and can be considered potential biomarkers.

A randomized phase 2 study comparing two doses of delafloxacin with tigecycline in adults with complicated skin and skin-structure infections.

PubMed

O'Riordan, William; Mehra, Purvi; Manos, Paul; Kingsley, Jeff; Lawrence, Laura; Cammarata, Sue

2015-01-01

A randomized, double-blind, multicenter trial was done to compare two doses of delafloxacin with tigecycline in patients with various complicated skin and skin-structure infections (wound infections following surgery, trauma, burns, or animal/insect bites, abscesses, and cellulitis). Patients were randomized 1:1:1 to receive delafloxacin 300mg intravenous (IV) every 12h, delafloxacin 450mg IV every 12h, or tigecycline 100mg IV×1, followed by 50mg IV every 12h; randomization was stratified by infection type. Duration of therapy was 5-14 days. The primary efficacy analysis, performed on the clinically evaluable (CE) population at the test-of-cure (TOC) visit (14-21 days after the final dose of study drug), compared clinical response rates in the delafloxacin and tigecycline arms. Clinical response rates in the two delafloxacin arms were also compared. Among CE patients, clinical cure rates at TOC visit were similar in the delafloxacin and tigecycline arms (94.3%, 92.5%, and 91.2%, respectively in delafloxacin 300-mg, delafloxacin 450-mg, and tigecycline arms). Overall, the most frequent adverse events were nausea, vomiting, and diarrhea; the 300-mg delafloxacin arm was the best-tolerated regimen. Delafloxacin was similarly effective as tigecycline for a variety of complicated skin and skin-structure infections and was well tolerated. (Clinicaltrials.gov NCT 0719810). Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Health burden of skin lesions at low arsenic exposure through groundwater in Pakistan. Is river the source?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fatmi, Zafar, E-mail: zafar.fatmi@aku.edu; Azam, Iqbal; Ahmed, Faiza

2009-07-15

A significant proportion of groundwater in south Asia is contaminated with arsenic. Pakistan has low levels of arsenic in groundwater compared with China, Bangladesh and India. A representative multi-stage cluster survey conducted among 3874 persons {>=}15 years of age to determine the prevalence of arsenic skin lesions, its relation with arsenic levels and cumulative arsenic dose in drinking water in a rural district (population: 1.82 million) in Pakistan. Spot-urine arsenic levels were compared among individuals with and without arsenic skin lesions. In addition, the relation of age, body mass index, smoking status with arsenic skin lesions was determined. The geographicalmore » distribution of the skin lesions and arsenic-contaminated wells in the district were ascertained using global positioning system. The total arsenic, inorganic and organic forms, in water and spot-urine samples were determined by atomic absorption spectrophotometry. The prevalence of skin lesions of arsenic was estimated for complex survey design, using surveyfreq and surveylogistic options of SAS 9.1 software.The prevalence of definitive cases i.e. hyperkeratosis of both palms and soles, was 3.4 per 1000 and suspected cases i.e. any sign of arsenic skin lesions (melanosis and/or keratosis), were 13.0 per 1000 among {>=}15-year-old persons in the district. Cumulative arsenic exposure (dose) was calculated from levels of arsenic in water and duration of use of current drinking water source. Prevalence of skin lesions increases with cumulative arsenic exposure (dose) in drinking water and arsenic levels in urine. Skin lesions were 2.5-fold among individuals with BMI <18.5 kg/m{sup 2}. Geographically, more arsenic-contaminated wells and skin lesions were alongside Indus River, suggests a strong link between arsenic contamination of groundwater with proximity to river.This is the first reported epidemiological and clinical evidence of arsenic skin lesions due to groundwater in Pakistan. Further investigations and focal mitigation measures for arsenic may be carried out alongside Indus River.« less

Characterization of a new transmission detector for patient individualized online plan verification and its influence on 6MV X-ray beam characteristics.

PubMed

Thoelking, Johannes; Sekar, Yuvaraj; Fleckenstein, Jens; Lohr, Frank; Wenz, Frederik; Wertz, Hansjoerg

2016-09-01

Online verification and 3D dose reconstruction on daily patient anatomy have the potential to improve treatment delivery, accuracy and safety. One possible implementation is to recalculate dose based on online fluence measurements with a transmission detector (TD) attached to the linac. This study provides a detailed analysis of the influence of a new TD on treatment beam characteristics. The influence of the new TD on surface dose was evaluated by measurements with an Advanced Markus Chamber (Adv-MC) in the build-up region. Based on Monte Carlo simulations, correction factors were determined to scale down the over-response of the Adv-MC close to the surface. To analyze the effects beyond dmax percentage depth dose (PDD), lateral profiles and transmission measurements were performed. All measurements were carried out for various field sizes and different SSDs. Additionally, 5 IMRT-plans (head & neck, prostate, thorax) and 2 manually created test cases (3×3cm(2) fields with different dose levels, sweeping gap) were measured to investigate the influence of the TD on clinical treatment plans. To investigate the performance of the TD, dose linearity as well as dose rate dependency measurements were performed. With the TD inside the beam an increase in surface dose was observed depending on SSD and field size (maximum of +11%, SSD = 80cm, field size = 30×30cm(2)). Beyond dmax the influence of the TD on PDDs was below 1%. The measurements showed that the transmission factor depends slightly on the field size (0.893-0.921 for 5×5cm(2) to 30×30cm(2)). However, the evaluation of clinical IMRT-plans measured with and without the TD showed good agreement after using a single transmission factor (γ(2%/2mm) > 97%, δ±3% >95%). Furthermore, the response of TD was found to be linear and dose rate independent (maximum difference <0.5% compared to reference measurements). When placed in the path of the beam, the TD introduced a slight, clinically acceptable increase of the skin dose even for larger field sizes and smaller SSDs and the influence of the detector on the dose beyond dmax as well as on clinical IMRT-plans was negligible. Since there was no dose rate dependency and the response was linear, the device is therefore suitable for clinical use. Only its absorption has to be compensated during treatment planning, either by the use of a single transmission factor or by including the TD in the incident beam model. Copyright © 2015. Published by Elsevier GmbH.

Comparative Evaluation of a Silicone Membrane as an Alternative to Skin for Testing Mosquito Repellents.

PubMed

Agramonte, Natasha M; Gezan, Salvador A; Bernier, Ulrich R

2017-05-01

Repellents prevent mosquito bites and help reduce mosquito-borne disease, a global public health issue. Laboratory-based repellent bioassays predict the ability of compounds to deter mosquito feeding, but the variety of repellent bioassays and statistical analysis methods makes it difficult to compare results across methodologies. The most realistic data are collected when repellents are applied on the skin; however, this method exposes volunteers to chemicals and mosquito bites. Silicone membranes were investigated as an alternative to human skin in assays of repellent efficacy. Results from module system bioassays conducted in vitro with a silicone membrane were compared with in vivo bioassays conducted with N,N-diethyl-3-methylbenzamide (referred to as DEET), 1-piperidinecarboxylic acid 2-(2-hydroxyethyl)-1-methylpropylester (referred to as Picaridin), ethyl 3-[acetyl(butyl)amino]propanoate (referred to as IR3535), and para-menthane-3,8-diol (referred to as PMD) applied directly on the skin of the leg. No significant difference in mosquito feeding was found when comparing skin and volunteer-worn membrane controls using blood; however, feeding was significantly lower in unworn membrane controls using either 10% sucrose or blood, indicating that worn membranes are a possible surrogate for untreated human skin. Pooled data from six volunteers were used to generate dose-response curves of blood-feeding activity. Results from skin-applied repellents were modeled to determine if membranes could provide a predictive correlate for skin. Goodness-of-fit comparisons indicated that the nonlinear dose-response curves for the skin and membrane differed significantly for DEET and Picaridin, but did not differ significantly for IR3535 and PMD. With knowledge of the dose-response relationships and further modifications to this system, the membrane-based tests could be used for standardized repellent testing with infected vectors. Published by Oxford University Press on behalf of Entomological Society of America 2016. This work is written by US Government employees and is in the public domain in the US.

Pharmacokinetics of Tedizolid in Plasma and Sputum of Adults with Cystic Fibrosis.

PubMed

Park, A Young J; Wang, Joshua; Jayne, Jordanna; Fukushima, Lynn; Rao, Adupa P; D'Argenio, David Z; Beringer, Paul M

2018-06-18

Over the past decade, the prevalence of infections involving Methicillin-resistant Staphylococcus aureus (MRSA) in patients with cystic fibrosis (CF) has increased significantly. Tedizolid (TZD) demonstrates excellent activity against MRSA and a favorable safety profile. The pharmacokinetics of several antibiotics has shown to be altered in CF patients. The purpose of this study was to characterize the pharmacokinetics of tedizolid in this population. Eleven patients with CF were randomized to receive tedizolid phosphate 200 mg PO or IV once daily for 3 doses, with minimum 2-day washout, followed by crossover to the remaining dosage form. Plasma and expectorated sputum were collected following the third dose of each dosage form for analysis. Population pharmacokinetics was performed using maximum-likelihood, expectation maximization method, and the disposition of TZD was described by a 2-compartment model. The sputum concentrations exceeded the unbound plasma concentrations with an estimated mean (%CV) sputum-to-unbound plasma penetration ratio of 2.88 (50.3). The estimated population mean ± standard deviation of total clearance, central volume of distribution, and bioavailability were 9.72 ± 1.62 L/h, 61.6 ± 6.94 L, and 1.04 ± 0.232 respectively. The total clearance is higher in CF patients when compared with healthy volunteers; however, it is similar to published data in patients with complicated skin and skin structure infections (cSSSI). This study demonstrates the oral bioavailability of tedizolid is excellent in patients with CF, and the plasma pharmacokinetics are similar to that reported for patients with cSSSI. Copyright © 2018 American Society for Microbiology.

Vehicle effects on human stratum corneum absorption and skin penetration.

PubMed

Zhang, Alissa; Jung, Eui-Chang; Zhu, Hanjiang; Zou, Ying; Hui, Xiaoying; Maibach, Howard

2017-05-01

This study evaluated the effects of three vehicles-ethanol (EtOH), isopropyl alcohol (IPA), and isopropyl myristate (IPM)-on stratum corneum (SC) absorption and diffusion of the [ 14 C]-model compounds benzoic acid and butenafine hydrochloride to better understand the transport pathways of chemicals passing through and resident in SC. Following application of topical formulations to human dermatomed skin for 30 min, penetration flux was observed for 24 h post dosing, using an in vitro flow-through skin diffusion system. Skin absorption and penetration was compared to the chemical-SC (intact, delipidized, or SC lipid film) binding levels. A significant vehicle effect was observed for chemical skin penetration and SC absorption. IPA resulted in the greatest levels of intact SC/SC lipid absorption, skin penetration, and total skin absorption/penetration of benzoic acid, followed by IPM and EtOH, respectively. For intact SC absorption and total skin absorption/penetration of butenafine, the vehicle that demonstrated the highest level of sorption/penetration was EtOH, followed by IPA and IPM, respectively. The percent doses of butenafine that were absorbed in SC lipid film and penetrated through skin in 24 h were greatest for IPA, followed by EtOH and IPM, respectively. The vehicle effect was consistent between intact SC absorption and total chemical skin absorption and penetration, as well as SC lipid absorption and chemical penetration through skin, suggesting intercellular transport as a main pathway of skin penetration for model chemicals. These results suggest the potential to predict vehicle effects on skin permeability with simple SC absorption assays. As decontamination was applied 30 min after chemical exposure, significant vehicle effects on chemical SC partitioning and percutaneous penetration also suggest that skin decontamination efficiency is vehicle dependent, and an effective decontamination method should act on chemical solutes in the lipid domain.

The abdominal skin of female Sprague-Dawley rats is more sensitive than the back skin to drug-induced phototoxicity.

PubMed

Kuga, Kazuhiro; Yasuno, Hironobu; Sakai, Yumi; Harada, Yumiko; Shimizu, Fumi; Miyamoto, Yumiko; Takamatsu, Yuki; Miyamoto, Makoto; Sato, Keiichiro

2017-11-01

In vivo phototoxicity studies are important to predict drug-induced phototoxicity in humans; however, a standard methodology has not established. To determine differences in sensitivity to drug-induced phototoxicity among various skin sites, we evaluated phototoxic reactions in the back and abdominal skin of female Sprague-Dawley rats orally dosed with phototoxic drugs (pirfenidone, 8-methoxysoraren, doxycycline, and lomefloxacin) or a non-phototoxic drug (gatifloxacin) followed by solar-simulated light irradiation comprising 18J/cm 2 ultraviolet A. Tissue reactions were evaluated by macroscopic and microscopic examination and immunohistochemistry for γ-H2AX, and tissue concentrations of pirfenidone, doxycycline, and lomefloxacin were measured by tandem mass spectrometry. In addition, the thicknesses of the skin layers at both sites were measured in drug-naïve rats. The abdominal skin showed more severe reactions to all phototoxic drugs than the back skin, whereas the minimal erythema dose in drug-naïve rats and skin concentrations of each drug were comparable between the sites. Furthermore, histopathological lesions and γ-H2AX-positive cells in the abdominal skin were detected in deeper layers than in the back skin. The stratum corneum and dermis in the abdominal skin were significantly thinner than in the back skin, indicating a difference in the depth of light penetration and potentially contributing to the site differences observed in sensitivity to phototoxicity. Gatifloxacin did not induce any phototoxic reactions at either site. In conclusion, the abdominal skin is more sensitive to drug-induced phototoxicity than the back skin and may represent a preferable site for irradiation in this rat phototoxicity model. Copyright © 2017 Elsevier Inc. All rights reserved.