The Preventive Effects of Boron-Based Gel on Radiation Dermatitis in Patients Being Treated for Breast Cancer: A Phase III Randomized, Double-Blind, Placebo-Controlled Clinical Trial.

INTRODUCTION: Radiation dermatitis (RD) is a side effect of radiation therapy (RT) which is experienced by over 90% of patients being treated for breast cancer. The current clinical trial was conducted to measure the preventative effects of a boron-based gel on several different clinical outcomes (dermatitis, erythema, dry desquamation, and moist desquamation) after 25 radiotherapy sessions. METHODS: This research used a double-blind parallel-group design with a placebo control (n = 76) and randomized group (n = 181), with all participants being between 18 and 75 years old. Fifteen minutes before each radiotherapy, participants in the intervention group were given a gel containing 3% sodium pentaborate pentahydrate, while those in the placebo group received a gel with no chemical substance. Dermatitis, erythema, dry desquamation, and moist desquamation were compared between the 2 groups. RESULTS: At baseline, there were no significant differences between the groups (p > 0.05), except for body mass index. After 14 days of treatment, dermatitis (98.7% vs. 9.9%; p < 0.001), erythema (96.1% vs. 12.2%; p < 0.001), dry desquamation (50% vs. 3.9%; p < 0.001), and moist desquamation (18.4% vs. 0.6%; p < 0.001) were much more common in the placebo group than the intervention group. To prevent dermatitis, erythema, dry desquamation, and moist desquamation in 1 patient, on average, 1.1 (95% confidence interval [CI]: 1.1-1.2), 1.2 (95% CI: 1.1-1.3), 2.2 (95% CI: 1.7-2.9), and 5.6 (95% CI: 3.8-11.0) patients need to be treated, respectively. CONCLUSION: The boron-based gel has a significant preventive effect on several categories of RD which might be used by clinicians in breast cancer.

Monte Carlo study on the secondary cancer risk estimations for patients undergoing prostate radiotherapy: A humanoid phantom study.

AIM: The aim of this study was to estimate the secondary malignancy risk from the radiation in FFB prostate linac-based radiotherapy for different organs of the patient. BACKGROUND: Radiation therapy is one of the main procedures of cancer treatment. However, the application the radiation may impose dose to organs of the patient which can be the cause of some malignancies. MATERIALS AND METHODS: Monte Carlo (MC) simulation was used to calculate radiation doses to patient organs in 18 MV linear accelerator (linac) based radiotherapy. A humanoid MC phantom was used to calculate the equivalent dose s for different organs and probability of secondary cancer, fatal and nonfatal risk, and other risks and parameters related to megavoltage radiation therapy. In out-of-field radiation calculation, it could be seen that neutrons imparted a higher dose to distant organs, and the dose to surrounding organs was mainly due to absorbed scattered photons and electron contamination. RESULTS: Our results showed that the bladder and skin with 54.89 × 10-3 mSv/Gy and 46.09 × 10-3 mSv/Gy, respectively, absorbed the highest equivalent dose s from photoneutrons, while a lower dose was absorbed by the lung at 3.42 × 10-3 mSv/Gy. The large intestine and bladder absorbed 55.00 × 10-3 mSv/Gy and 49.08 × 10-3, respectively, which were the highest equivalent dose s due to photons. The brain absorbed the lowest out-of-field dose, at 1.87 × 10-3 mSv/Gy. CONCLUSIONS: We concluded that secondary neutron portion was higher than other radiation. Then, we recommended more attention to neutrons in the radiation protection in linac based high energy radiotherapy.

Application of the phase-space distribution approach of Monte Carlo for radiation contamination dose estimation from the (n,γ), (γ,n) nuclear reactions and linac leakage photons in the megavoltage radiotherapy facility.

AIM: The aim of this study was to characterize the radiation contamination inside and outside the megavoltage radiotherapy room. BACKGROUND: Radiation contamination components in the 18 MV linac room are the secondary neutron, prompt gamma ray, electron and linac leakage radiation. MATERIALS AND METHODS: An 18 MV linac modeled in a typical bunker employing the MCNPX code of Monte Carlo. For fast calculation, phase-space distribution (PSD) file modeling was applied and the calculations were conducted for the radiation contamination components dose and spectra at 6 locations inside and outside the bunker. RESULTS: The results showed that the difference of measured and calculated percent depth-dose (PDD) and photo beam-profile (PBP) datasets were lower than acceptable values. At isocenter, the obtained photon dose and neutron fluence were 2.4 × 10-14 Gy/initial e° and 2.22 × 10-8 n°/cm2, respectively. Then, neutron apparent source strength (QN) value was found as 1.34 × 1012 n°/Gy X at isocenter and the model verified to photon and neutron calculations. A surface at 2 cm below the flattening filter was modeled as phase-space (PS) file for PDD and PBP calculations. Then by use of a spherical cell in the center of the linac target as a PS surface, contaminant radiations dose, fluence and spectra were estimated at 6 locations in a considerably short time, using the registered history of all particles and photons in the 13GB PSD file as primary source in the second step. CONCLUSION: Designing the PSD file in MC modeling helps user to solve the problems with complex geometry and physics precisely in a shorter run-time.

MC safe bunker designing for an 18 MV linac with nanoparticles included primary barriers and effect of the nanoparticles on the shielding aspects.

AIM: The aim of this study was to design a safe bunker for an 18 MV linac in to configuration; primary barriers made from nanoparticle-containing concrete and pure concrete. BACKGROUND: Application of some nanoparticles in the shielding materials has been studied and it was shown that the presence of some nanoparticles improved radiation shielding properties. MATERIALS AND METHODS: Some percentage of different nanoparticles were modeled by the MCNP5 code of MC in the megavoltage radiotherapy treatment room's primary barriers. Other parts of the designed room, such as secondary barriers and maze door, were modeled as ordinary pure concrete. A safe bunker was designed according to the MC derived spectra at primary and secondary barriers location using a modeled and benchmarked 18 MV linac in free air. Then, the thickness of the required shielding materials for the door and also concrete for the walls and primary barriers were calculated separately. RESULTS: According to the results, required concrete thickness in primary and secondary barriers was reduced by around 0.8% compared to pure concrete application. Additionally, required lead and BPE decreased by 25% and 15%, respectively, due to primary barriers nanoparticles. CONCLUSIONS: It was concluded that application of some nanoparticles in the shielding materials structures in megavoltage radiotherapy can make the shielding effective.