bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of the formation mechanism of proline-containing cyclic dipeptide from the linear peptide
Authors: Otsuka Yuuki , Arita Hikaru , Sakaji Michio , Yamamoto Kenji , Kashiwagi Takehiro , Shimamura Tomoko , Ukeda Hiroyuki 
Published: August 2019

ABSTRACTCyclic dipeptides, 2,5-diketopiperazines (DKPs), are well-known bioactive and taste compounds in food. DKPs have also been reported in various foods and particularly, Pro-containing DKPs (cyclo(-X-Pro)) are more predominant in heated and fermented foods than other type of DKPs. However, the mechanism underlying the preferential formation of Pro-containing DKPs in food remains uncertain. Herein, we attempted to elucidate the effects of reaction conditions and the mechanism of DKPs formation. The reaction conditions (heating time, heating temperature, and pH) and amino acid sequence of the linear peptides were important for the DKPs formation from linear peptides. In addition, Pro-containing DKPs were significantly formed from linear peptides with the second amino acid from the N-terminus being Pro. Based on these results, the underlying mechanism of the enrichment of Pro-containing DKPs in foods was proposed.
Surface dose accuracy in VMAT head and neck radiation treatment using bolus
Authors: Alexander KM , Gooding J , Schreiner LJ , Olding T 
Published: August 2019

Abstract
The accuracy of EclipseTM-calculated head and neck VMAT plan dose delivery was assessed in the situation when there is a gap between placed bolus on a head and neck thermoplastic mask and the body surface. GafchromicEBT3 film dosimetry was used for dose delivery validation. The results from 3%, 3 mm 2D gamma comparison indicate better than 95% agreement between measured film dose and calculated plan dose for gap widths up to 25 mm between placed bolus and body surface.
Polymer gel-based measurements of the isocenter accuracy in an MR-LINAC
Authors: Dorsch S , Mann P , Elter A , Runz A , Klüter S , Karger C P 
Published: August 2019

Abstract
As magnetic resonance-guided radiotherapy (MRgRT) is becoming increasingly important in clinical applications, the development of new quality assurance (QA) methods is needed. One important aspect is the alignment of the radiation and imaging isocenter. MR-visible polymer gels offer a way to perform such measurements online and additionally may allow for 3-dimensional (3D) evaluation. We present a star shot measurement irradiated and scanned with a 0.35 T MR-LINAC device evaluating the polyacrylamide gelatin (PAGAT) gel dosimeter immediately and 48 h after irradiation. The gel was additionally scanned at a 3 T MR device 5 h and 52 h after irradiation. The evaluation revealed an isocircle radius of 0.5 mm for both imaging devices and all image resolutions and time points after irradiation. The distance between radiation and imaging isocenter varied between 0.25 mm and 1.30 mm depending on the applied image resolution. This demonstrates that evaluation of a star shot measurement in a 0.35 T MR-LINAC is feasible, even immediately after irradiation.
Characterization of small PRESAGE® samples for measurements near the dosimeter edges
Authors: Costa Filipa , Doran Simon , Adamovics John , Nill Simeon , Hanson Ian M , Oelfke Uwe 
Published: August 2019

Abstract
Measurements near the edges of PRESAGE® 3D dosimeters will be important for validating the electron return effect (ERE) that can occur at tissue-air interfaces during radiotherapy treatment delivered with the Elekta MR-linac. We investigate and characterize the spatially non-uniform response of small samples of PRESAGE® to radiation in a conventional linac. We develop a correction to compensate for these non-uniformities and obtain dose values near the dosimeter edges. Five samples from the same batch were uniformly irradiated in a water tank with a broad beam. The non-uniform response of the samples to radiation was investigated and a radial dose-correction function was generated from each sample to obtain a correction image. We then applied these correction images to another sample from the same batch, irradiated with four beams in an inhomogeneous medium, and compared this with the relevant simulated data. Additionally, we irradiated samples after physically removed their edges (axially and top and bottom edges). Higher sensitivity to radiation was observed at the edges (~6mm) of the samples in comparison with the central region. Applying the dose correction function improved agreement between simulations and measurements, but only partial correction was possible. A uniform response was observed on the samples with the edges removed, which we propose as the best option to measure dose at the edges of PRESAGE® samples.
The MD Anderson experience with 3D dosimetry and an MR-linac
Authors: Ibbott Geoffrey S. , Le Hannah J. , Roe Yvonne 
Published: August 2019

Abstract
A recent extension of image guidance in radiation therapy has been brought about by the introduction of the MR-linac; a hybrid system comprising an MR imager and a medical linear accelerator. The University of Texas MD Anderson Cancer Center is one of seven institutes around the world that have collaborated with the manufacturer to develop this system and bring it into clinical use. In the process, a great deal has been learned about the influence of the magnetic field on radiation dose deposition and upon dosimetry systems. A number of dosimetry systems have been evaluated and issues affecting their performance have been investigated. The potential value of three-dimensional dosimetry systems has been explored.
SRS and SBRT and advanced dosimetry: Duke experiences
Authors: Oldham Mark 
Published: August 2019

Abstract
Stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) are among the most demanding of radiation therapy techniques in terms of requirements for high accuracy and conformality of treatment delivery. Compared to conventional treatments, they require specialized high-precision equipment (including high specification medical accelerators and alignment frames), extensive imaging (including multi-modal and motion management methods), specialized Quality Assurance protocols, and increased person-power effort. In addition, the high dose-per-fraction renders SRS/SBRT a high-stakes treatment setting, where small errors may cause significant treatment morbidity in normal healthy tissue. All of these issues combine to render SRS/SBRT one of the most opportunistically rich and clinically important areas for advanced dosimetry research. Some of the applications of advanced 3D dosimetry to SRS and SBRT and small field treatment verification are explored. Applications include base of skull IMRT, single-isocenter multi-lesion radiosurgery, pre-clinical precision treatments, interpreting the clinical significance of 3D QA data, remote dosimetry, dosimetry in magnetic fields, trigeminal neuralgia, rodent-morphic dosimetry, motion, and small field commissioning.
Influence of the components of a radiochromic PVA – Iodide gel dosimeter on the optical dose response
Authors: Hayashi Shin-Ichiro , Ono Kaoru , Fujino Keisuke , Fujimoto Sachie 
Published: August 2019

Abstract
A novel radiochromic gel dosimeter based on a poly(vinyl alcohol)-iodide complex (PVA-I) has been developed with the aim of using it in optical computed tomography (CT). The PVA-I gel dosimeter exhibits excellent characteristics such as high sensitivity, dose rate independence, a wide dose range, and especially reusability. The standard PVA-I gel dosimeter is composed of poly(vinyl alcohol) (average degree of polymerization 1000 and degree of saponification 88 mol%), iodide (potassium iodide), reducing sugar (fructose), gelling agent (gellan gum), and water. In this study, the influence on dose response is investigated upon substitution of the components by PVAs with different degrees of polymerization (500, 1500, 3500) and saponification (80 mol%, 98 mol%), different iodide salts (LiI, NaI, NH4I), and different reducing sugars (glucose, maltose, lactose). The results show that these substitutions have little effect on the dose rate dependence, while the iodide salt affects the sensitivity.
Preliminary investigation of a reusable radiochromic sheet for radiation dosimetry
Authors: Collins Cielle , Kodra Jacob , Yoon Suk Whan , Coakley Robert , Adamovics John , Oldham Mark 
Published: August 2019

Abstract
This work investigates a novel reusable radiochromic sheet developed as an economic film substitute or as a radiochromic bolus. The radiation-induced optical density (OD) change of the sheet is read-out with a commercial flat-bed optical scanner. An optimized readout procedure was developed including an optimal scan-time window. Fundamental radiochromic properties of the sheets were characterized including temporal decay of OD, dose sensitivity and consistency through repeated irradiations, and temperature sensitivity. The radiation induced OD change in the sheets was found to decay to baseline within ~24 hours, after which the sheet could be reused. The sensitivity of subsequent re-irradiations was found to be consistent within ±5% (coefficient of variation of 4.5%) for at least 6 irradiations and potentially many more. Importantly, the sheets were not observed to carry any detectable memory of previous irradiations within measurement uncertainty. In conclusion, the Presage sheets show promise as an economic multi-purpose alternative for film applications and potentially as a radiochromic bolus. Further work is required to test the sheet in diverse clinical applications, and to develop a softer material for bolus applications.
Development of a reusable PVA-GTA-I gel dosimeter for 3D radiation dose assessments
Authors: Taño J , Hayashi S , Hirota S , Gonzales CA , Yasuda H 
Published: August 2019

Abstract
A novel formula of crosslinked polyvinyl alcohol (PVA) with glutaraldehyde (GTA), a tri-iodide complex, and glucono-δ-lactone (GDL) acid for gel dosimetry was investigated in the present study. The objectives of this study were to evaluate the formula’s dose response properties through spectrophotometry and possible reusability by reannealing. After production, the gel samples were irradiated from 1 to 70 Gy of gamma-rays from a Cs-137 source with a constant dose rate of 0.857 Gy/min. Spectrum data were obtained using a UV-Vis spectrophotometer and analyses were done for dose linearity, dose sensitivity versus GTA concentration, and absorbance profile versus time. The resulting unirradiated gel samples were colorless and transparent, while the irradiated samples turned to a reddish-brown hue with a peak absorbance response at 490 nm. Dose linearity results indicated R2 values of 0.9, 0.986 and 0.8 for GTA concentrations of 7 mM, 15 mM and 30 mM, respectively. Moreover, dose sensitivity is higher for lower concentrations of GTA. Time progression results indicated that the absorbance decreases within one day after irradiation and increases subsequently. Through reannealing for 24 hours at 45°C in an oven, a colorless material with an absorbance value identical to the unirradiated samples was finally made for samples irradiated from 1 to 20 Gy, while the 70 Gy irradiated sample had a significant decrease in color and absorbance peak. This radiochromic gel dosimeter is promising and should be useful for 3D radiation dose assessments. Further investigation of the formula and preparation techniques are suggested for future experiments.
Three-dimensional radiochromic and polymer gel dosimeters with Pluronic F-127 matrix – a review of current research
Authors: Kozicki M , Jaszczak M , Kwiatos K , Maras P , Kadlubowski S , Wach R , Dudek M 
Published: August 2019

Abstract
A co-polymer of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic F-127, PEO-PPO-PEO) was proposed as a physical gel matrix, substituting gelatine for three-dimensional polymer gel dosimeters and as a matrix for the preparation of new radiochromic gel dosimeters. Two polymer gel dosimeters and seven radiochromic gel dosimeters were obtained with this new matrix. In this review we summarise the main advantages of using Pluronic F-127 for manufacturing radiation dosimeters and the best performing new Pluronic dosimeters.
Making and assessing 3D dosimeters
Authors: Jordan Kevin , De Deene Yves 
Published: August 2019

Abstract
Several 3D dosimeters are commercially available. However, there are many circumstances that require a customized 3D dosimeter. Examples include feasibility tests of non-standard treatment modalities, inhomogeneous tissue configurations, unique shapes and sizes and teaching. In this session, general approaches for preparing radiochromic dosimeters, Fricke and polymer gel dosimeters, micelle gel and silicone dosimeters were presented. Advise will be given to developers of new 3D dosimeters. For optical readout, light absorption and scatter can limit the practical size of dosimeters. Specifically, increasing from 5 to 15 cm diameter dosimeters is optically challenging. Strategies to maximize initial optical transmission were presented. For MRI readout, the dose resolution is determined by both the dosimeter sensitivity and the pulse sequence parameters and the accuracy is determined by the sensitivity of the dosimeter to temperature and dose rate, next to imaging performance. For X-ray CT imaging, the dose resolution is determined by the sensitivity of the dosimeter which largely depends on the polymer density that can be achieved. The importance of characterizing the dosimeter in terms of dose sensitivity and stability, spatial integrity, dose rate and fractionation dependence, oxygen and ambient light sensitivity, temperature sensitivity and thermal history were emphasized. The dosimeter requirements also dictate the types of vessels and scanners appropriate for readout. For example, the preferred dosimeter formulation may include a compound that is incompatible with the preferred vessel.
Comparison of low dose proton and photon irradiation induced polymerization processes in advanced nMAG gels using Raman spectroscopy
Authors: Šeperienė N , Adlienė D 
Published: August 2019

Abstract
A rapid development of the new radiation based cancer treatment technologies that are more individualized and patient oriented request precise 3D treatment dose verification methods in high dose gradient fields. Polymeric dose gels are excellent 3D dosemeters that allow analysis of spatial dose distribution in the irradiated target and also in the regions out of the target since the investigation of low dose induced secondary effects (secondary cancer, inflammations) stands on the priority list. Since the sensitivity of dose gel to different types of irradiation depends on radiation induced polymerization processes, in this work we present Raman analysis results related to advanced nMAG dose gels polymerization upon its irradiation with high energy photons and protons to doses ≤ 5 Gy.
Clear micelle gel dosimeter with nanoclay
Authors: Hayashi K , Nemoto M , Takanashi T , Kang Y , Togo H , Kotoku J , Kobayashi T , Mihashi M , Hayashi S , Gotoh H 
Published: August 2019

Abstract
We built a clear micelle gel dosimeter with nanoclay. Jordan et al. reported that Laponite RD clay nanoparticles when added to radiochromic leucomalachite green micelle gels eliminate diffusion and increase the dose sensitivity by roughly ten folds. However, owing to the cloudiness of the sample, there was a problem in reading the optical computed tomography (CT). In this study, we constructed a nanoclay-added micelle gel dosimeter by changing the type of gelatin. As a result, in addition to yielding a clear gel and making the optical CT readable, diffusion and temporal stability were improved more than the gel without using nanoclay, and the dosimeter showed the same level of sensitivity and diffusion as the one based on Laponite-added micelle gel reported by Jordan et al.
Novel dual-wavelength optical-CT imaging method for gel dosimeter readout
Authors: Du Yi , Wang Xiangang , Xiang Xincheng , De Deene Yves 
Published: August 2019

Abstract
Dual-wavelength scanning is a technique eliminating the need of phantom repositioning for optical-CT gel readout. To further diminish artifacts caused by phantom impurities, we hereby propose a novel dual-wavelength imaging method based on phantom impurity recognition and correction. In this method, impurities in motion trajectories during phantom rotation are recognized at the reference wavelength via motion-tracking as a binary mask, which is then applied to correct impurity-contaminated pixels at the data wavelength. Compared with the existent dual-wavelength imaging method, the proposed method is demonstrated to be capable of reducing impurity-induced artifacts and improving imaging SNR and CNR in the same process.
Spatial dose distribution analysis of Co-60 HDR brachytherapy of cervical cancer using an AQUAJOINT®-based VIPET polymer gel dosimeter
Authors: Oe Ayumi , Nemoto Mikio , Miyazawa Masanori , Sahade Daniel Antonio , Hamada Toshimasa 
Published: August 2019

Abstract
High-dose rate brachytherapy treatment has become more complicated with the use of three-dimensional image-guided brachytherapy (3D-IGBT) to prepare treatment plans using 3D images, such as those obtained from computed tomography (CT). In planning a 3D-IGBT, spatial measurement of dose distribution verification is recommended. In this study, the spatial dose distribution of intrauterine cavity irradiation by a Co-60 sealed brachytherapy source was acquired using an AQUAJOINT® polymer gel dosimeter. A CT/magnetic resonance imaging (MRI) compatible applicator was inserted into the gel in a bottle. It was irradiated and visualized using MRI. The image was converted to an R2 image using a DD-System (R-TECH INC, Japan), and dose distribution was evaluated using the dose–R2 response curve. The obtained dose distribution, dose profile of the radiotherapy treatment planning system, isodose curve, and gradient passing were calculated. In the dose profile, the dose difference was large near the applicator (high-dose region) and was less than ±2% in the middle-dose region. The isodose curves showed good agreement in the region of 2–6 Gy near the prescription point. The gamma analysis was 87.594% on the sagittal cross-section and 93.711% on the coronal cross-section based on the dose difference (DD)/distance to agreement (DTA) of 3%/3 mm.
Dose reconstruction including dynamic six-degree of freedom motion during prostate radiotherapy
Authors: Muurholm C G , Ravkilde T , Skouboe S , Eade T , Nguyen D T , Booth J , Keall P J , Poulsen P R 
Published: August 2019

Abstract
An in-house developed program for real-time reconstruction of motion-induced dose errors, DoseTracker, was extended to handle rotational target motion in addition to the previously implemented translational motion, and applied offline for prostate VMAT treatments. For translational motion, the motion-induced errors of DoseTracker were in good agreement with ground truth dose reconstructions performed in a commercial treatment planning system. For rotational motion, no ground truth was available, but DoseTracker showed that the VMAT dose is highly robust against static interfractional rotations but quite sensitive to dynamic intrafraction rotations due to interplay effects between target motion and machine motion.
Development of an experimental 3-D tool based on radiochromic films to determine normal tissue doses in external radiotherapy
Authors: Colnot J , Garnier G , Zefkili S , Dumas J-L , Gschwind R , Huet C 
Published: August 2019

Abstract
External radiotherapy largely proved its efficacy to treat cancer. However, this technique leads to unavoidable exposure of normal tissues that may results in adverse effects. One of the main concerns is the induction of second cancers that may appear at the periphery or even away from the treated area. Risk estimation models need accurate 3-D dosimetric data on healthy organs. To this aim, we developed an experimental tool based on radiochromic films measurements. In this work, we present a study performed with a heterogeneous phantom. EBT3 films were positioned in between the phantom slices and irradiated according to a VMAT plan. The dose was reconstructed in 3-D by interpolation thanks to an in-house Matlab tool. Two interpolation methods are studied and the reconstructed dose is compared to independent film measurements for validation. Finally, dosimetric data such as DVH are compared to the TPS evaluation. Continuous interpolation proves to better reconstruct the doses in high gradient areas whereas linear interpolation seems to be a better option to evaluate doses away from the field edge. Besides, TPS and 3-D measurements give comparable results for organs placed inside the beams (maximum 6.3% difference on organs mean doses). However, the TPS tends to underestimate doses to organs placed at least partially outside the fields (from 29 to 59% difference on mean doses). Optimization of the dose reconstruction tool by using a combination of the two interpolation methods is ongoing. Comparison with gel dosimetry will also be investigated.
EPIDs and QA of advanced treatments
Authors: Mijnheer B 
Published: August 2019

Abstract
In this paper I will summarize the various possibilities of EPIDs for their use as tools for QA of advanced treatments. After elucidating the choice of EPIDs for this purpose, I will review the use of EPIDs for pre-treatment and in vivo (transit) dosimetry applications. Several solutions became recently commercially available, allowing relative and/or absolute dose verification at points (0D), in 2D, or in 3D. Each of these solutions will be briefly discussed, indicating the differences in possibilities with respect to QA of advanced treatments. I will conclude with some general remarks about the current status of EPID-based QA of advanced treatments and revealing some future developments in 3D pre-treatment and in vivo dosimetry using EPIDs.
End to end QA in image guided and adaptive radiation therapy
Authors: Schreiner L J 
Published: August 2019

Abstract
It has been suggested that modern radiation therapy could benefit from adopting the “End to End” (E2E) type of testing developed originally in computer science to determine whether applications and systems work as required under real-world scenarios. The motivation for adopting E2E techniques for image guided adaptive radiation therapy validation is to extend beyond current common testing using standard physics QA that inherently probes only select points or systems within the IGART schema. E2E methodologies extend the testing to evaluate complete IGART processes, including the complex interchanges that occur during and throughout a patient’s treatment as clinical staff interpret and respond to information acquired during the treatment course.
While limited radiotherapy E2E QA may have been adopted periodically by clinics when implementing a new treatment technique, clinical E2E QA has been confined to date mainly to tests mediated by external auditing bodies such as IROC, the Imaging and Radiation Oncology Core in the United States. This testing often includes having the clinic in question irradiate a purpose-built phantom containing dosimeters to specific criteria under protocols set by the auditing body. The auditors then determine off site whether the clinic’s treatment process was successful by comparing the dose measurements with the intended dose delivery.
The advance of three dimensional (3D) radiation dosimeters opens the possibility for in-house E2E testing. Approaches for in-house E2E testing have been proposed for over a decade, but such comprehensive internal E2E testing has not been widely adopted. In this presentation the barriers and challenges to the development of clinical in-house E2E QA will be reviewed primarily based on the experience in Kingston.