Stereotactic radiosurgery with immune checkpoint inhibitors for brain metastases: a meta-analysis study.

BACKGROUND: Immune checkpoint inhibitors (ICIs) are an emerging tool in the treatment of brain metastases (BMs), Stereotactic radiosurgery (SRS), traditionally used for BMs, elicits an immune brain response and can act synergistically with ICIs. We aim to investigate the efficacy of ICI administered with SRS and determine the impact of timing on BM response. METHODS: A systematical search was performed to identify potential studies concerning BMs managed with SRS alone or with SRS + ICI with relative timing administration (ICI concurrent with SRS, ICI nonconcurrent with SRS, SRS before ICI, SRS after ICI). The overall survival (OS), 12-month OS, local progression-free survival (LPFS), 12-month local brain control (LBC), distant progression-free survival (DPFS), 12-month distant brain control (DBC), and adverse events (intracranial hemorrhage, radionecrosis) were analyzed using the random-effects model. RESULTS: A total of 16 retrospective studies with 1356 BM patients were included. Compared to nonconcurrent therapy, concurrent therapy revealed a significantly longer OS (HR= 1.43; p = 0.008) and 12-months LBC (HR = 1.91; p = 0.04), a similar 12-months DBC (HR = 1.12; p = 0.547) and higher complication rate (R = 0.77; p = 0.346). Concurrent therapy leads to a significantly higher OS compared to ICI before SRS (HR = 2.55; p = 0.0003). CONCLUSION: The combination of SRS with ICI improves patients' clinical and radiological outcomes. The effectiveness of the combination is subject to the identification of an optimal therapeutic window.

Impact of low level radiation on concentrations of some trace elements in radiation workers.

INTRODUCTION: Small variations in trace element levels may cause important physiological changes in the human body. This study aims to evaluate five important trace elements in radiation workers. METHOD: In this study, 44 radiation workers and an equal number of non-radiation workers were selected as the case and control group, respectively. The concentrations of iron, magnesium, zinc, copper, and selenium in the serum of the participants were measured using an Atomic Absorption Spectrometry (AAS). RESULTS: The mean concentrations of iron, magnesium, zinc, copper, and selenium for the case group were 107.3 µg/dl, 2.3 mg/dl, 80.9 µg/dl, 112.6 µg/dl and 216.7 ng/ml, respectively. The results for the control group were 121.9 µg/dl, 2.3 mg/dl, 82.3 µg/dl, 112.8 µg/dl and 225.2 ng/ml, respectively. CONCLUSIONS: The mean concentration of iron in the case group was significantly lower than the control group (p-value = 0.012), while the concentrations of other elements in both of the groups were not significantly different. In the case group, except magnesium (p-value = 0.021), no significant relationship was found between age and the elemental concentrations. According to Spearman's test, there was a meaningful statistical correlation between the sex and concentration of iron, Mg, Zn, and Se. Also, the correlation between the concentration of magnesium and the weights of radiation workers was significant (p-value =0.044).

Efficacy of stereotactic radiosurgery as single or combined therapy for brain metastasis: A systematic review and meta-analysis.

To determine the efficacy of stereotactic radiosurgery (SRS) in treating patients with brain metastases (BMs), a network meta-analysis (NMA) of randomized controlled trials (RCTs) and a direct comparison of cohort studies were performed. Relevant literature regarding the effectiveness of SRS alone and in combination with whole-brain radiotherapy (WBRT) and surgery was retrieved using systematic database searches up to April 2019. The patterns of overall survival (OS), one-year OS, progression-free survival (PFS), one-year local brain control (LBC), one-year distant brain control (DBC), neurological death (ND), and complication rate were analyzed. A total of 18 RCTs and 37 cohorts were included in the meta-analysis. Our data revealed that SRS carried a better OS than SRS+WBRT (p = 0.048) and WBRT (p = 0.041). Also, SRS+WBRT demonstrated a significantly improved PFS, LBC, and DBC compared to WBRT alone and SRS alone. Finally, SRS achieved the same LBC as high as surgery, but intracranial relapse occurred considerably more frequently in the absence of WBRT. However, there were not any significant differences in ND and toxicities between SRS and other groups. Therefore, SRS alone may be a better alternative since increased patient survival may outweigh the increased risk of brain tumor recurrence associated with it.

Synthesis, characterization, and in vitro and in vivo 68Ga radiolabeling of thiosemicarbazone Schiff base derived from dialdehyde dextran as a promising blood pool imaging agent.

To be used as a carrier of 68Ga radioisotope for possible blood pool imaging studies, dialdehyde dextran thiosemicarbazone (DADTSC) Schiff base polymer with different thiosemicarbazone contents (TSCC) = 0.93, 2.43, and 3.4 mmol/g were synthesized and characterized by FT-IR, GPC, and CHNS. Although they were successfully radiolabeled at room temperature, stable radio-complexes were prepared at 60 °C. Effect of thiosemicarbazone content on the dissolution rate, cytotoxicity, coagulation and hemolysis activities, and radiolabeling efficiency of Schiff bases as well as on the in-vitro radio-complexes stability was investigated. DADTSC1 (TSCC = 0.93 mmol/g) showed a less cytotoxicity (cell viability, CV50 = 490 µg/ml), a better solubility, suitable coagulation and hemolytic activities, and a sufficient radiolabeling efficiency (Radiochemical purity (RCP) > 95%) and formed a stable (RCP > 90%) radio-complex, which be chosen for in-vivo biodistribution study in healthy rats through tissue sampling and counting for radioactivity. Like blood pool imaging agents, 68Ga-DADTSC1 presented a retention profile in blood circulation, though more studies, including imaging in larger mammals, are required.

Evaluating the effect of the vacuum bag on the dose distribution in radiation therapy.

INTRODUCTION: Immobilization of patients in radiation therapy can be performed with a vacuum bag (VB). The aim of this study is to measure the effect of the VB in the surface and depth dose of patients in radiation therapy. MATERIALS AND METHODS: The effect of the VB on the surface dose and depth dose is measured in clinical conditions. Various dosimeters were used in following measurements: parallel plate chamber for depth dose, farmer ionization chamber for various gantry angles, and Mapcheck2 dosimeter for various thicknesses of VB. The effect of VB cap, which may be placed in the beam path, is also measured using EDR2 film. The measurements were performed for 6 MV and 18 MV photons with an Oncor linac. RESULTS: The increase of 30% and 25% in the surface dose with VB was observed for 6 MV and 18 MV, respectively. Though due to the use of VB, the reduction of the absorbed dose at a 5 cm depth is under 1% and can be ignored in MU calculation. For various thicknesses of VB, 8-14 cm, the attenuation of the primary beam were up to 2.5% for 6 MV and 1.2% for 18 MV photon. The presence of VB cap in the path of radiation reduced the depth dose up to 15% and 11% for 6 MV and 18 MV, respectively. CONCLUSION: The use of VB can increase the surface dose of the patient up to 30% and this fact should be considered in treatment planning. For some lateral fields the cap of the VB may interfere with radiation field. If the cap of VB is placed in the beam path, it can cause a cold spot in tumor. DISCUSSION: The use of VB can increase the surface dose of the patient up to 30%. For some lateral fields, the cap of the VB might interfere with the radiation field. If the cap of VB is placed in the beam path, it can cause a cold spot in the tumor volume.

An investigation of gamma background radiation in Hamadan province, Iran.

The general population, everywhere in the world is exposed to a small dose of ionising radiation from natural sources. Stochastic effects such as cancer and genetic disorders are caused when living creatures are exposed to low doses. In Iran, it is measured in some cities, especially in high-background areas such as Ramsar, but so far there is no measurement in the Hamadan province. Hamadan is located in the west of Iran. Measurements were performed using a RDS-110 survey meter, CaSO(4):Dy thermoluminecense dosimetries (TLDs) and a Harshaw 4000 TLD reader. To estimate the dose rate  outdoors, four stations along the main directions (north, south, west and east) and one in the town centre were selected. Mean annual X and gamma equivalent dose in Hamadan province are 1.12±0.22  and 1.66±0.07 mSv, which related to RDS-110 survey meter and TLDs measurements, respectively. The TLDs and RDS-110 results are representative of the external photon radiation doses for the selected monitoring locations and for those locations for the hours during which the measurements were taken, respectively. Maximum and minimum of external photon radiation doses are related to Hamadan and Kaboudar-Ahang towns, respectively. According to the results of the study, it seems that the annual X and gamma equivalent dose in Hamadan province exceeded the global mean external exposure amounts by the UNSCEAR, and further studies are needed to measure internal exposures to determine the total environmental radiation level in  Hamadan province.