Evaluation of the radiation protection effectiveness of a lead-free homopolymer in cone beam computed tomography.

OBJECTIVE: The objective was to compare the radiation protection effectiveness of a lead-free thermoplastic homopolymer (Anti-RAD) to conventional lead shielding in cone beam computed tomography (CBCT) exposures. STUDY DESIGN: Thermoluminescent dosimeters were placed on a human bone- and soft tissue-equivalent phantom to record equivalent doses in the thyroid gland, thyroid skin, and breast areas. CBCT images were obtained with the following 3 protocols: (1) without radiation shielding; (2) with 0.5-mm lead equivalent lead-containing shielding; and (3) with 0.5-mm lead equivalent Anti-RAD shielding. Independent t tests were used to evaluate the results. RESULTS: Compared with exposures without shielding, both lead and Anti-RAD protective devices reduced thyroid gland equivalent doses by approximately 40%, thyroid skin doses by approximately 75%, right breast skin doses by approximately 80%, and left breast skin doses by 75%. The differences in equivalent dose for both types of shielding compared with exposure with no shielding were statistically significant (P ≤ .042). However, there were no significant differences in dose reduction at any site between lead and Anti-RAD shielding (P ≥ .135). CONCLUSIONS: Radiation protection equivalent to lead can be provided with the Anti-RAD shield. With the use of this material, disadvantages such as damage to the aprons, lead toxicity, weight of lead aprons, and microbial contamination can be reduced.

Preparation of alginate coated Pt nanoparticle for radiosensitization of breast cancer tumor.

Noble metals as high atomic number elements can localize X-ray radiation within tumor cells by exploiting different mechanisms. Here, alginate (Alg)-coated platinum nanoparticles (Pt@Alg) were synthesized, characterized, and implemented as a radiosensitizer to enhance X-ray therapeutic efficacy in breast cancer in vitro and in vivo. Alg not only improves the biocompatibility of the radioenhancer, but also stabilizes the nanoparticles. Pt@Alg was studied by different characterization methods including DLS, STEM, Fe-SEM, XRD, XPS, FT-IR and UV-Vis spectrophotometry. The nanosystem provided a higher level of intracellular ROS in malignant cells and enhanced cancer cell death under X-Ray irradiation. Clonogenic assay also demonstrated the radiosensitizing properties of the nanosystem, in vitro. In vivo result show tumor growth restraining properties of the nanosystem when it was administrated along with X-Ray irradiation. Histopathology results confirmed the impact of nanosystem and X-ray co-treatment, as well. Altogether, the importance of radiosensitizers for improving radiotherapy outcomes was highlighted.

Enhanced In Vivo Radiotherapy of Breast Cancer Using Gadolinium Oxide and Gold Hybrid Nanoparticles.

Radiation therapy has demonstrated promising effectiveness against several types of cancers. X-ray radiation therapy can be made further effective by utilizing nanoparticles of high-atomic-number (high-Z) materials that act as radiosensitizers. Here, in purpose of maximizing the radiation therapy within tumors, bovine serum albumin capped gadolinium oxide and gold nanoparticles (Gd2O3@BSA-Au NPs) are developed as a bimetallic radiosensitizer. In this study, we incorporate two high-Z-based nanoparticles, Au and Gd, in a single nanoplatform. The radiosensitizing ability of the nanoparticles was assessed with a series of in vitro tests, following evaluation in vivo in a breast cancer murine model. Enhanced tumor suppression is observed in the group that received radiation after administration of Gd2O3@BSA-Au NPs. As a result, cancer therapy efficacy is significantly improved by applying Gd2O3@BSA-Au NPs under X-ray irradiation, as evidenced by studies evaluating cell viability, proliferation, reactive oxygen species production, and in vivo anti-tumor effect.

Evaluation of volumetric modulated arc therapy (VMAT) - based total body irradiation (TBI) in pediatric patients.

BACKGROUND: The dosimetric characterization of volumetric modulated arc therapy (VMAT)-based total-body irradiation (TBI) in pediatric patients is evaluated. MATERIALS AND METHODS: Twenty-two patients between the ages of 2 and 12 years were enrolled for VMAT-based TBI from 2018 to 2020. Three isocenters were irradiated over three overlapping arcs. While prescribing 90% of the TBI dose to the planning treatment volume (PTV), two fractions (2 Gy each) were delivered each day; hence 12 Gy was delivered in six fractions. During treatment optimization, the mean lung and kidney doses were set not to exceed 7 Gy and 7.5 Gy, respectively. The maximum lens dose was also set to less than 4 Gy. Patient quality assurance was carried out by comparing treatment planning system doses to the 3-dimensional measured doses by the ArcCHECK® detector. The electronic portal imaging device (EPID) gamma indices were also obtained. RESULTS: The average mean lung dose was 7.75 ± 0.18 Gy, mean kidney dose 7.63 ± 0.26 Gy, maximum lens dose 4.41 ± 0.39 Gy, and the mean PTV dose 12.69 ± 0.16 Gy. The average PTV heterogeneity index was 1.15 ± 0.03. Average differences in mean kidney dose, mean lung dose, and mean target dose were 2.79% ± 0.88, 0.84% ± 0.45 and 0.93% ± 0.47, respectively; when comparing planned and ArcCHECK® measured doses. Only grade 1-2 radiation toxicities were recorded, based on CTCAE v5.0 scoring criteria. CONCLUSIONS: VMAT-TBI was characterized with good PTV coverage, homogeneous dose distribution, planned and measured dose agreement, and low toxicity.

An institutional experience of quality assurance of a treatment planning system on photon beam.

AIM: The purpose of the present study is to show the application of the IAEA TRS-430 QA procedures of Eclipse™v7.5 TPS for photon energies. In addition, the trends of the deviations found in the conducted tests were determined. BACKGROUND: In the past, the lack of complete TPS QA procedures led to some serious accidents. So, QA in the radiotherapy treatment planning process is essential for determination of accuracy in the radiotherapy process and avoidance of treatment errors. MATERIALS AND METHODS: The calculations of TPS and measurements of irradiations of the treatment device were compared in the study. As a result, the local dose deviation values (δ 1: central beam axis, δ 2: penumbra and build up region, δ 3: inside field, δ 4: outside beam edges, δ 50-90: beam fringe, RW50: radiological width) and their confidence limit values (including systematic and random errors) were obtained. RESULTS: The confidence limit values of δ 4 were detected to increase with expanding field size. The values of δ 1 and δ 3 of hard wedge were larger than open fields. The values of δ 2 and δ 50-90 of the inhomogeneity effect test were larger, especially than other tests of this study. The average deviation was showed to increase with the rise of the wedge angle. The values of δ 3 and δ 4 of lung irradiation were outside tolerance. CONCLUSIONS: The QA of TPS was done and it was found that there were no reservations in its use in patient treatment. The trend of the deviations is shown.

Comparison of total body irradiation plus cyclophosphamide with busulfan plus cyclophosphamide as conditioning regimens in patients with acute lymphoblastic leukemia undergoing allogeneic hematopoietic stem cell transplant.

Conditioning regimens used during stem cell transplant provide prolonged control or cure of the disease in patients with acute lymphoblastic leukemia (ALL). In this study, we present a comparison of treatment results for 95 patients with ALL who underwent allogeneic hematopoietic stem cell transplant (AHSCT) with total body irradiation plus cyclophosphamide (TBI + Cy) or busulfan plus cyclophosphamide (Bu + Cy) as conditioning regimen. Median age was 25 (range: 9-54) years. Median follow-up was 24 (range: 3-107) months. Median overall survival (OS) was found to be 29 months. Median event-free survival (EFS) was 9 months. Median OS was 37 months in the TBI + Cy arm, while it was 12 months in the Bu + Cy arm, suggesting a significant advantage favoring the TBI + Cy arm (p = 0.003). Median EFS was 13 months in the TBI + Cy arm, while it was 4 months in the Bu + Cy arm, indicating a significant difference (p = 0.006). In univariate and multivariate analysis, it was found that high OS and EFS were significantly correlated with TBI + Cy conditioning regimen and lack of transplant-related mortality (p < 0.05). The TBI + Cy conditioning regimen was found to be superior to the Bu + Cy regimen in patients with ALL undergoing AHSCT regarding both OS and EFS.

Experimental posterior perforating ocular injury in rabbit eyes: effects of radiotherapy with or without intravitreal cyclosporin on vitreous proliferation.

Double perforating ocular injuries were made in 30 rabbits and the effects of radiotherapy (RT) alone or in combination with cyclosporin (CS) on vitreous proliferation investigated. Thirteen rabbits in group 1 received RT alone (600 cGy), and 13 rabbits in group 2 received RT combined with 100 microg of intravitreal CS. No treatment was given to 4 rabbits in the control group (group 3). All animals were ophthalmologically examined on the 1st, 3rd, 7th, 14th and 28th days following the injury and the clinical findings scored; they were sacrificed on the 28th day, and histopathological scoring was made. The median histopathological score of the RT group (4.0; range: 0-8) was significantly higher than that of the CS + RT group (1.0; range: 0-5; p = 0.018). We conclude that intravitreal CS may be used as an adjunctive agent to RT to inhibit intraocular proliferation following penetrating ocular injury in rabbits.

Comparison of the effects of laser and ultrasound treatments on experimental wound healing in rats.

A randomized controlled study investigated the effects of ultrasound and laser treatments on wound healing in rats. The duration of the inflammatory phase decreased with both laser and ultrasound treatments; however, laser was more effective than ultrasound, with more significant results. The proliferation phase showed, for both treatments, an increase in the level of hydroxyproline and the number of fibroblasts, as well as stimulation of the collagen synthesis and the composition. Laser treatment was again more effective than ultrasound. The wound breaking strength was significantly higher with both treatments, and no statistically significant difference emerged between the laser and ultrasound groups, although laser treatment provided a much greater increase in the wound breaking strength than ultrasound. Both treatments have beneficial effects on the inflammatory, proliferation, and maturation phases of wound healing. Both can be used successfully for decubitis ulcers and chronic wounds, in conjunction with conventional therapies such as debridement and daily wound caring. However, laser treatment was more effective than ultrasound in the first two phases of wound healing.