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Adjuvant radiotherapy is an important treatment modality after breast-conserving surgery. Due to its proximity, radiation therapy for the left breast can often lead to an escalated heart dose that can result in heart diseases. The purpose of this study was to evaluate the heart dose reduction by using lead shields surrounding the left breast. The doses of a 3D conformal radiotherapy (3D-CRT) plan, an intensity-modulated radiotherapy (IMRT) plan, and volumetric-modulated arc therapy (VMAT) to the left breast tumor in a CIRS ATOM anthropomorphic female adult phantom were measured by optically stimulated luminescence dosimeters (OSLDs). To protect critical organs, the skin around the target area was covered by lead shields of two different thicknesses (0.125 mm and 0.25 mm). The results showed that compared to IMRT and 3D-CRT, VMAT provided better planning target volume (PTV) coverage, a better conformity index (CI), and homogeneity index (HI). With the use of lead shields, the thyroid dose was reduced by 5.12–27.5% and 20.51–30%, respectively, the heart dose was reduced by 49.41–50.12% and 56.38–57.42%, respectively, and the lung dose was reduced by 1.23–45.22% and 0.98–57.83%, respectively. Although the clinical application of lead shields was rare, this study verified that it could effectively decrease the heart dose from 4.31 ± 0.09 Gy to 1.88–2.18 Gy, thereby potentially reducing the risk of associated heart diseases by 14.8%. Further works to implement this method into clinical practice are needed.

Electron paramagnetic resonance (EPR) dosimetry is a physical method for the retrospective dose assessment for radiation accident. It can be used to detect and measure free radical concentration proportional to the absorbed dose of the sample. The purpose of the work is to establish the conversion coefficients between the absorbed dose of tooth/fingernail and the whole body effective dose. The calibration curves of signal-dose for EPR and electric charge-dose for thermoluminescent dosimeter (TLD) were first established. Linear regression of the relationship has a high R-squared (>0.99) for different radiation modalities with different amounts of energy. The Rando phantom with embedded TLDs at each critical organ was irradiated using the photon beams (6, 10 MV) and the electron beams (6, 9, and 12 MeV) from the linear accelerator. Accordingly, the conversion coefficients between tooth/fingernail dose and whole-body effective dose or between tooth/fingernail dose and the organ dose were derived based on the measurements of TLDs. The effective dose and the absorbed dose of organs can be roughly and quickly estimated by employing the proposed conversion coefficients based on the EPR measurements of teeth and fingernails in case of a radiation accident. As such, the radiation injuries those exposed suffer can be identified for categorization using the EPR measurements.

With advancements in aesthetic medicine, breast augmentation has become a popular plastic surgery worldwide, typically performed using either fine-needle injection or silicone implants. Both carry complication risks from rupture over time. In this study, we aimed to reduce misjudgments and increase diagnostic value by developing an MRI technique that can produce water- and silicone-specific images from MRI scans of phantoms (Natrelle® saline-filled breast implants) and human bodies. Pig oil, soybean oil, and normal saline were used to simulate human breast tissue, and two common types of breast implants, saline bags, and silicone bags, were selected as well, resulting in five materials scanned. Six pulse sequences were applied: T1W fast spin echo (FSE), T1W SPGR/60, T2W, T2W fat-saturation, STIR, and STIR water-saturation. Human body scans were additionally investigated using 3D SPGR fat-saturation dynamic contrast enhancement. Results show that the best way to enhance tissue contrast in images of silicone implants is to apply STIR combined with water suppression, and the best way to enhance saline bag implants is to apply T2W fat-saturation combined with fat suppression. Both offered very high sensitivity and specificity, rendering this method especially useful for distinguishing normal mammary glands from siliconoma.

The purpose of this study is to establish the minimal injection doses of magnetic resonance imaging (MRI) contrast agents that can achieve optimized images while improving the safety of injectable MRI drugs. Gadolinium-diethylenetriamine penta-acetic acid (Gd-DTPA) and ferucarbotran, commonly used in clinical practice, were selected and evaluated with in vitro and in vivo experiments. MRI was acquired using T1-weighted (T1W) and T2-weighted (T2W) sequences, and the results were quantitatively analyzed. For in vitro experiments, results showed that T1W and T2W images were optimal when Gd-DTPA-bisamide (2-oxoethyl) (Gd-DTPA-BMEA) and ferucarbotran were diluted to a volume percentage of 0.6% and 0.05%, all comparisons were significant differences in grayscale statistics using one-way analysis of variance (ANOVA). For in vivo experiments, the contrast agent with optimal concentration percentages determined from in vitro experiments were injected into mice with an injection volume of 100 &mu, L, and the images of brain, heart, liver, and mesentery before and after injection were compared. The statistical results showed that the p values of both T1W and T2W were less than 0.001, which were statistically significant. Under safety considerations for MRI contrast agent injection, optimized MRI images could still be obtained after reducing the injection concentration, which can provide a reference for the safety concentrations of MRI contrast agent injection in the future.

This study aimed to compare different types of right breast cancer radiotherapy planning techniques and to estimate the whole-body effective doses and the critical organ absorbed doses. The three planning techniques are intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT, two methods) and hybrid 3D-CRT/IMRT (three-dimensional conformal radiotherapy/intensity-modulated radiotherapy). The VMAT technique includes two methods to deliver a dose: non-continuous partial arc and continuous partial arc. A thermoluminescent dosimeter (TLD) is placed in the RANDO phantom to estimate the organ absorbed dose. Each planning technique applies 50.4 Gy prescription dose and treats critical organs, including the lung and heart. Dose-volume histogram was used to show the planning target volume (V95%), homogeneity index (HI), conformity index (CI), and other optimized indices. The estimation of whole-body effective dose was based on the International Commission on Radiation Protection (ICRP) Publication 60 and 103. The results were as follows: Continuous partial arc and non-continuous partial arc showed the best CI and HI. The heart absorbed doses in the continuous partial arc and hybrid 3D-CRT/IMRT were 0.07 &plusmn, 0.01% and 0% (V5% and V10%, respectively). The mean dose of the heart was lowest in hybrid 3D-CRT/IMRT (1.47 Gy &plusmn, 0.02). The dose in the left contralateral lung (V5%) was lowest in continuous partial arc (0%). The right ipsilateral lung average dose and V20% are lowest in continuous partial arc. Hybrid 3D-CRT/IMRT has the lowest mean dose to contralateral breast (organs at risk). The whole-body effective doses for ICRP-60 and ICRP-103 were highest in continuous partial arc (2.01 Sv &plusmn, 0.23 and 2.89 Sv &plusmn, 0.15, respectively). In conclusion, the use of VMAT with continuous arc has a lower risk of radiation pneumonia, while hybrid 3D-CRT/IMRT attain lower secondary malignancy risk and cardiovascular complications.

Retrospective dosimetry is one of the most important tools of accident dosimetry for environmental dose estimation when large-scale radiological incidents and nuclear mass-casualty events occur. Electron paramagnetic resonance (EPR) dosimetry is a physical method for the retrospective assessment of absorbed dose based on the measurement of stable radiation-induced radicals in materials. Different from the fast disappearance of radials in aqueous systems, the radials can persist indefinitely in some organized matrices. Therefore, environmental materials contained in creatures from sea or land can be potentially used as environmental dosimeters for a retrospective dose analysis. This study aims to assess the EPR signals of free radicals from environmental biological samples, potentially for the retrospective dose estimation. The evaluated samples involve ox bone, cyclina shell, clam shell, chitin from squid, and human tissue (enamel and fingernail). First, we dehydrate and grind these materials to the powder with different sizes. Subsequently, all materials were irradiated with different doses ranging from 5 Gy to 50 Gy using 6 MV linear accelerator, and EPR spectra of these materials were obtained from the calculation of peak-to-peak amplitudes. The dose-response curve of EPR signals versus irradiated dose for the six materials shows good linearity (R2~0.99). For the grain-size experiment, the ox bone and tooth with 0.5 mm, the chitin with 0.1 mm, and the others with 1 mm have the strongest signal. For the storage temperature experiment, the optimal temperature of storage is at &minus, 20 &deg, C for tooth, fingernail, ox bone, and chitin, at 45 &deg, C for clam shell and cyclina shell where the signal fading is minimal. In conclusion, the developed dose-response curves of the six materials may potentially help a fast, rough retrospective dose reconstruction under the environment when radiation accidents occur.

This study aimed to evaluate the effects of fogging on the effectiveness of a lead glass shield in protecting an operator from radiation exposure during conventional coronary angiography (CAG). Optically stimulated luminescence dosimeters (OSLDs) were used to measure the effects of fogged lead glass shields (FLSs) and clear lead glass shields (CLSs) on the radiation doses of a cardiac catheterization surgeon. We simulated the scatter radiation incident on the operator with five angiographic projections with 10-s exposures. Experiments were conducted with a field of view of 25 cm, maximum of 100 cm between the X-ray tube and image intensifier, and 80 cm between the image intensifier and operator. Lead glass fogging had no significant effect at any angiographic projection. The average dose at the lens of the eye, thyroid glands, and gonads did not differ significantly between FLS and CLS. Although most surgeons view ceiling-suspended shields as hindrances during surgical procedures, the radiation dose at the operator’s eyes and thyroid glands increased by 13 and 10 times without the shield. The fogging of the shield is probably caused by post-surgery UV decontamination or detergents. An operator has no cause for concern regarding the radiation protection afforded by an FLS during CAG procedures.

Crystal defects such as the doping of a variety of various elements are known to enhance the optically stimulated luminescent dosimeter (OSLD) performance of Al 2 O 3 . Moreover, the use of Au nanoparticles (NPs) has attracted considerable attention because of their photoluminescence properties. In this paper, a facile method is proposed to prepare and disperse Au NPs on an Al 2 O 3 surface. The effects of Au nanoparticles on linearity between light emission and dose, reusability, and angular dependence of our proposed Au/Al 2 O 3 OSLD are examined and discussed. We found that the linearity between light emission and dose with a wider dose range from 5 Gy to 30 Gy can be obtained. The sensitivities were tuneable by adjusting the Au/Al 2 O 3 ratio. The result also shows a comparable angular dependence properties with commercially-available Al 2 O 3 :C dosimeters. In addition, the optical bleaching durations of Au/Al 2 O 3 and Al 2 O 3 :C phosphors were also studied, in which the required bleaching time for our proposed Au/Al 2 O 3 was 2 h shorter than for Al 2 O 3 :C. In other words, this research also helps to reduce the bleaching time before re-use.

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.

Digital radiography is currently the main method of medical imaging diagnosis. It also has a wide range of applications across different fields. This study used radiation to conduct non-destructive visual imaging, and further established a quantitative analysis for visual gray-scale images to determine changes in the quality of eggs. Eggs of the same weight with three quality classes were chosen according to the egg labels available on the market. Furthermore, a general medical X-ray digital imaging system was used to apply two-dimensional digital radiography. A photometric interpretation of monochrome gray-scale imaging established by the Digital Imaging and Communications in Medicine (DICOM) standard was used to conduct a quantitative stratification analysis of the matrix data visualization, along with one-way analysis of variance (ANOVA) for quantitative statistics of the gray-scale values for the three structures, i.e., shell, air cell, and yolk. The statistical results showed that X-ray digital gray-scale images and a quantitative stratification analysis of the matrix data visualization results are less easily identified based on visual differences. In the quantitative statistical results of the one-way ANOVA gray-scale values, the whole-egg and in-egg quantitative matrix analysis both show p &lt, 0.05. In the analysis of egg freshness, the quantitative statistics of the percentage of space occupied by the air cell in the eggs also showed p &lt, 0.05. In addition, the results of the freshness of each egg were graded. The quality and freshness of the eggs can be quantitatively analyzed through radiographic imaging. The results of this study will provide a more scientific and quantitative reference for the quality and freshness of agricultural products in the future.

Treatment planning for patients with synchronous bilateral breast cancer (SBBC) is challenging due to the technical complexity of bilateral treatment. To minimize both high-dose and low-dose volumes of the heart and lungs being irradiated, we proposed an efficient and simple strategy for volumetric modulated arc therapy (VMAT) treatment planning in this study. Five SBBC patients were enrolled in this study. We utilized two pseudo block planning structures to minimize the high-dose volume of the whole lungs and heart and confine the low-dose areas in normal organs for VMAT planning. The prescription delivered was 45 Gy in 25 fractions to the whole breast. The VMAT treatment plan consisted of two partial arcs. In terms of the whole lungs, the average V5Gy, V10Gy and V20Gy in the VMAT-B plan (with two pseudo planning block structures) for the five patients were 34.8 ± 7.2%, 23.4 ± 5.0% and 14.8 ± 3.0%, respectively. For the VMAT-NB plan (without two pseudo planning block structures), the average V5Gy, V10Gy and V20Gy were 38.6 ± 6.8%, 27 ± 5.9% and 18.4 ± 4.0%, respectively. For the heart, the average V5Gy, V10Gy, V20Gy and V30Gy in the VMAT-B plan were 19.6 ± 3.1%, 7.0 ± 2.5%, 2.2 ± 1.2% and 0.7 ± 0.7%, respectively, while the mean values in the VMAT-NB plan were 26.2 ± 6.3%, 11.3 ± 3.9%, 3.9 ± 1.8% and 1.5 ± 1.1%, respectively. We designed an approach to reduce both the high-dose and low-dose volumes by utilizing pseudo planning structures in the VMAT treatment plan. The dosimetric results of this study showed that the pseudo block structures have the potential to reduce the risks of radiation pneumonitis and heart disease, while preserving the same tumor control rate.

Whole-brain radiotherapy (WBRT) with hippocampal avoidance improves neurocognitive function deterioration. To improve both planning and treatment efficiency, we investigated the feasibility of using the coplanar volumetric-modulated arc therapy (VMAT) technique with various head flexion angles for hippocampal avoidance during WBRT. Six patients with brain metastases were selected for the study. We rotated patient CT images by 90° and changed the couch angle to simulate different head flexion angles. The plan with a head angle of 0° had the lowest planning target volume (PTV) coverage and the highest normal organ dose (i.e., hippocampus and bilateral lenses). When the angle was equal to or greater than 15°, the maximum dose of the hippocampus and the PTV V30 met all dose constraints. The results obtained with head angles equal to or greater than 25° were better than those obtained at angles below 25° with the obviously decreased dose of the bilateral lenses. The VMAT treatment plans of each patient were computed under various head flexion angles using the Eclipse Treatment Planning System. The study demonstrated that 15° is the minimum head flexion angle that should be adopted in clinical practice. For better dose coverage and uniformity for whole-brain PTV and dose reduction of critical organs, the study results suggested utilizing a head angle equal to or greater than 25°, while ensuring that patient comfort is maintained with larger head flexion angles. Compared with non-coplanar linac-based techniques, a tilted head angle with the coplanar VMAT technique not only reduces plan complexity but also improves treatment efficiency.

In radiotherapy for colorectal cancer, control of the testicular dose in young patients is important, as exposure of the testis could lead to temporary or permanent infertility. Although the testis is located out of the treatment field in patients receiving radiotherapy, it is inevitably exposed to scattered radiation resulting from the interaction between primary beams and patients and collimators. In this study, dosimeters were used to measure the testicular dose with and without testicular shielding to verify the effect of shielding. Anthropomorphic phantoms representing a human were used to estimate the doses absorbed in testicular and whole-body studies. The anthropomorphic phantom was irradiated according to the treatment protocol for colorectal cancer. Measurements were made using optically-stimulated luminescent dosimeters (OSLDs), composed of carbon-doped aluminum oxide, with characteristics suitable for radiotherapy dosimetry studies. A set of OSLDs was placed on a testicular phantom, attached to the lower edge of the pelvis of the anthropomorphic phantom. Dosimeters were also placed surround a testicular shielding to estimate the scattered dose. The testicular dose was 60–85 cGy when a dose of 4500 cGy was delivered to the whole pelvic area, while the dose was reduced to 34–50 cGy when testicular shielding was used. In addition, the increase in the surrounding scattered dose due to the testicular shielding was not significant.