This study compared the dosimetric accuracy of HyperArc versus conventional VMAT stereotactic radiosurgery (SRS) plans for multiple brain metastases using stringent quality assurance (QA) metrics. 60 HyperArc and 60 VMAT single-isocenter plans were evaluated using ion chamber point dose measurements, EPID-based planar portal dosimetry (PDIP), and 3D dose verification with an Octavius 4D phantom. Key metrics included absolute dose differences and gamma passing rates at 3 %/1 mm, 2 %/2 mm, and 2 %/1 mm. Both techniques met QA thresholds with high agreement between planned and delivered doses. Ion chamber measurements showed minimal deviation (similar to 4 % for both), and EPID gamma analyses yielded median passing rates similar to 99-100 % for both HyperArc and VMAT at 3 %/1 mm and 2 %/2 mm. Even under the tight 2 %/1 mm criterion, all plans maintained >95 % gamma pass rates. HyperArc demonstrated consistently lower dose deviations and slightly higher gamma agreement at the most stringent criteria; although differences were small and often not significant, effect size analysis revealed a consistent trend favoring HyperArc under tighter criteria. In 3D phantom QA (PTW; Octavius 4D), HyperArc achieved significantly higher gamma passing rates than VMAT at 3 %/1 mm and 2 %/1 mm (p < 0.05). Notably, one VMAT plan's gamma passing rate approached the failure threshold (similar to 90 %) at 2 %/1 mm. HyperArc plans also exhibited smaller absolute dose errors in both portal and phantom measurements. Both HyperArc and standard VMAT SRS achieved high dosimetric accuracy, but HyperArc provided more consistent dose agreement under the most rigorous QA evaluation, indicating a modest dosimetric advantage in complex multi-target SRS delivery.

Radiotherapy is the cornerstone in cancer treatment; it aims to deliver the prescribed treatment dose to the tumor tissue with consideration of reducing the toxicity risk of scattering radiation on the surrounding healthy organs. Recently, low dose radiation has been playing a crucial role in the treatment of benign tumors and other diseases such as Orthroathrites. Low-dose radiation is believed to exert a positive influence on biological systems, a concept explained by the theory of radiation hormesis. This study aims to investigate the impact of different low doses on the immunity and antioxidant activities of the biological systems. An animal model (Rats) was exposed to whole body irradiation to 10 cGy, 25 cGy and 50 cGy in different groups and after that, blood samples were collected after 24 hours from irradiation to measure CD4+ and CD8+ T cell levels by flow cytometry, while antioxidant enzymes (SOD, CAT, and GPx) were assessed using a spectrophotometer. The results indicated that there is a gradually increase with the exposed radiation with comparing to the control group as 34.10 ± 0.06, 39.17 ± 0.010, 49.33 ± 0.045, 62.23 ± 0.009 for CD4+ and 29.23 ± 0.023, 32.83 ± 0.035, 46.40 ± 0.016 and 55.47 ± 0.022 for CD8+ for control, 10 cGy, 25 cGy and 50 cGy groups respectively. The anti-oxidant activities exhibit increasing in, SOD, CA and, GPx in compare to the control Group .The recorded values of SOD, Ca, and GPX were 12.75±1.15, 66.98±0.97, and 33.28±1.48 U/ml for 10 cGy group, while they were 5.97 ± 0.56, 43.35 ± 1.93 and, 21.10 ± 1.30 U/ml for the 25 cGy group and, they were 4.18 ± 0.56, 29.45 ± 1.09, and 13.57 ± 0.65 U/ml for the 50 cGy group. In addition to statistical significance, the magnitude of treatment effects was quantified using effect size analysis, allowing clearer interpretation of how meaningfully each radiation dose influenced immune and antioxidant responses. The effect size has been calculated for all parameters, it was Cohen’s d >>>0.8 for CD4+, CD8+ in 10 cGy, 25 cGy and 50 cGy and antioxidant levels in 10 cGy only and Cohen’s d <<<0.8 in antioxidant levels in 25 cGy and 50 cGy levels which means that 10 cGy has a radiobiological significant impact. In general, based on these results, it can be concluded that 10 cGy can induce a hormesis effect while 25 cGy and 50 cGy have a beneficial effect on immunity but, it induces oxidative stress in the biological system. These findings support a hermetic model and suggest a critical dose threshold that separates beneficial from harmful effects. This insight may inform dose optimization strategies in radiotherapy and radioprotection.

Brain metastases pose a challenging situation in oncology with a requirement for accurate treatment modalities to achieve maximum tumor control with minimal toxicity. Hypofractionated SRS has emerged as a promising technique, with Volumetric Modulated Arc Therapy (VMAT) and HyperArc being two advanced delivery methods. Though HyperArc has been reported to have dosimetric advantages in single-fraction SRS, it has not been investigated in fractionated SRS. The present study compared the dosimetric characteristics of HyperArc and VMAT in hypofractionated SRS in several brain metastases. This is a comparative study that compares the treatment planning of 45 patients with 3-10 metastases who are treated with 30 Gy in five fractions using VMAT and HyperArc on a TrueBeam linear accelerator. Dosimetric parameters like target coverage (TC), conformity index (CIPaddick), homogeneity index (HI), gradient index (GI), and organ-at-risk (OAR) doses were measured. utilized Statistical tests were paired t-test, Pearson correlation, Bland-Altman analysis, Cohen's d-effect size, and Monte Carlo simulations to compare dose distributions. HyperArc had improved target coverage (98.89 % vs. 83.61 %, p < 0.05) and improved conformity (CIPaddick = 0.98 vs. 0.71, p < 0.05) with a sharper dose gradient (GI = 1.83 vs. 2.38, p < 0.05). It also had lower OAR doses with a significant reduction in exposure to the brainstem, spinal cord, optic chiasm, and optic nerves (p < 0.05). Monte Carlo simulations also demonstrated higher dose stability with HyperArc. HyperArc demonstrated superior dose conformity, sharper gradients, and enhanced OAR sparing in hypofractionated SRS, suggesting its potential for improving treatment precision and reducing toxicity. These findings support HyperArc as a preferred approach for optimizing stereotactic radiotherapy in patients with multiple brain metastases.

HyperArc treats brain metastases using one isocenter for many lesions, enhancing precision and efficiency. For accurate dosage distribution, TrueBeam LINAC with HyperArc must be geometrically isocentric. This study compares the MPC's HyperArc technology QA on TrueBeam systems to the Winston-Lutz (WL) test. The TrueBeam LINAC was assessed for geometric accuracy, isocenter alignment, couch positioning precision, repeatability, and MPC strength. For 60 days, MPC and WL were tested across QA measurements. The isocenter size, kV/MV imager offset accuracy, couch position, and measurement reliability were assessed using Levene's variance test, paired t-tests, and confidence interval (CI) assessments. Monte Carlo simulations were conducted to compare variance and variation in both approaches. Both methods were tested for machine performance parameter sensitivity using deliberate miscalibrations. MPC repeatability showed smaller standard deviations than WL across all geometric parameters. MPC couch position has a standard deviation of 0.02-0.06 mm, while WL has up to 0.20 mm. The mean isocenter size for WL was 0.39 mm (SD: 0.02 mm), while the mean MPC value was 0.28 mm (SD: 0.01 mm), demonstrating that WL consistently overestimated the size. A paired t-test (t = -56.80, p < 0.0001) and Monte Carlo simulations confirm a significant difference between the two techniques. These results improved using kV imager offset measurements. The MPC had an average offset of 0.17 mm (SD: 0.032 mm), and the WL had an average offset of 0.36 mm (t = -29.77, p < 0.0001). In this study, MPC outperformed WL in accuracy.

The motivation of this study is to check the dosimetry of small field sizes used in various treatment techniques using different methods (Monte Carlo simulations and detectors). We created two Monte Carlo models for Elekta Versa HD linear accelerators using EGSnrc (BEAMnrc-DOSXYZnrc) codes. Previous studies led us to define one model with an ideal symmetry full‐width‐half‐maximum (FWHM) of 0.15 cm in the x and y directions for the Gaussian distribution of the primary electron source and redefine the other with a larger asymmetry FWHM of 0.35 cm in the X and 0.6 cm in the Y directions. We calculated the penumbra width using both models. We measured output factors using two different detectors including Razor Diode which is designed especially for small field size measurements and compared them with both models. Using these detectors aims to investigate different detector sensitivities for dose measurements. In addition, patient-specific planning quality assurance (PSQA) for four fictional cases using Elekta Versa HD with Nasopharyngeal, Astrocytoma, right cerebellum, and right breast cancers were done using an IBA—2D array and compared to the minimum segment width parameter in Monaco Treatment planning system (TPS) for (0.5 and 1) cm segment width. The results indicated that Monte Carlo simulation shows increasing in the values of penumbra width with increasing the size of FWHM for field size range 0.5 × 0.5 to 3 × 3 (in-plane: 0.33 to 0.45 for model 1 and 0.46 to 0.65 for model 2, cross-plane: 0.29 to 0.38 for model 1 and 0.44 to 0.62 for model 2). The results indicate that output factors decrease as FWHM increases. The Razor Diode and CC04 detectors show consistent results up until a field size of 1 × 1 cm2. Additionally, plans with a minimum segment width of 0.5 cm demonstrate a lower gamma passing rate (GPR) compared to those with a 1 cm segment width. In conclusion, Inaccurate modeling of the FWHM of the primary source can lead to a significant error in the calculation when using a Monte Carlo model of the beam; Accordingly, this may lead to inaccurate delivery of treatment dose for cancer patients, in addition, this error increases as we go down field size 1 × 1 cm2 to reach an unacceptable level in field size 0.5 × 0.5 cm2. Thus, and as found, we can conclude that: to produce a more accurate radiotherapy treatment plan which in turn will lead to high-quality treatment for cancer patients, It is recommended that, during the beam-shaping process in IMRT or VMAT optimization, the minimum dimensions of any individual beamlet or segment within the treatment field should not be smaller than 1 × 1 cm2.

AbstractIn this paper, we demonstrated the biological effects of acute low-dose neutrons on the whole body of rats and investigated the impact of that level of neutron dose to induce an in vivo radio-adaptive response. To understand the radio-adaptive response, the examined animals were exposed to acute neutron radiation doses of 5 and 10 mSv, followed by a 50 mSv challenge dose after 14 days. After irradiation, all groups receiving single and double doses were kept in cages for one day before sampling. The electron paramagnetic resonance (EPR) method was used to estimate the radiation-induced radicals in the blood, and some hematological parameters and lipid peroxidation (MDA) were determined. A comet assay was performed beside some of the antioxidant enzymes [catalase enzyme (CAT), superoxide dismutase (SOD), and glutathione (GSH)]. Seven groups of adult male rats were classified according to their dose of neutron exposure. Measurements of all studied markers are taken one week after harvesting, except for hematological markers, within 2 h. The results indicated lower production of antioxidant enzymes (CAT by 1.18–5.83%, SOD by 1.47–17.8%, and GSH by 11.3–82.1%). Additionally, there was an increase in red cell distribution width (RDW) (from 4.61 to 25.19%) and in comet assay parameters such as Tail Length, (from 6.16 to 10.81 µm), Tail Moment, (from 1.17 to 2.46 µm), and percentage of DNA in tail length (DNA%) (from 9.58 to 17.32%) in all groups exposed to acute doses of radiation ranging from 5 to 50 mSv, respectively. This emphasizes the ascending harmful effect with the increased acute thermal neutron doses. The values of the introduced factor of radio adaptive response for all markers under study reveal that the lower priming dose promotes a higher adaptation response and vice versa. Ultimately, the results indicate significant variations in DNA%, SOD enzyme levels, EPR intensity, total Hb concentration, and RDWs, suggesting their potential use as biomarkers for acute thermal neutron dosimetry. Further research is necessary to validate these measurements as biodosimetry for radiation exposure, including investigations involving the response impact of RAR with varied challenge doses and post-irradiation behavior.

Prostate cancer (PC) is the second most prevalent cancer in males, with a steadily increasing incidence in the Middle East (ME). The aim of this study was to capture real-world data on the characteristics, disease progression, and treatment patterns among PC patients in the ME. This was a retrospective, observational, multi-centre study conducted across ten hospitals/research centers in Lebanon, Kingdom of Saudi Arabia, Iraq and Kuwait. Data were abstracted from medical records of 615 male patients who were diagnosed with PC between January 2012 and the site initiation date (December 2018-May 2019) and received at least one PC treatment/intervention. The observation period ranged between 84 and 88 months. Data were collected on demographics, clinical characteristics, time to progression to the subsequent clinical state or therapy (progression from localised/locally advanced PC to castration and to metastatic PC (metastatic castration-sensitive PC (mCSPC) or metastatic castration-resistant PC (mCRPC)), progression from mCSPC to mCRPC, and mCRPC patients' progression to first subsequent line of therapy), treatment patterns, and mortality. Most patients had localised/locally advanced PC (57.7%), followed by mCSPC (37.4%), and mCRPC (4.1%) at the time of inclusion in the study. Most patients were at tumours, nodes and metastases (TNM) stage IIIa (40.1%) or TNM stage IVb (27.8%) at study entry. Median time to metastatic disease, castration-resistance and next line therapy was 84 months (95% CI: 68-84), 41 months (95% CI: 30-56) and 7 months (95% CI: 0-41), respectively. The mortality rate was 3.6%. Disease progression was most common among patients with mCSPC (35.1%) or mCRPC (14.8%), and treatment discontinuation was most common among patients with mCRPC (36.6% treatments discontinued). The results show that most patients were at an advanced TNM stage at study entry, suggestive of a lack of awareness regarding PC. Disease progression was most common among patients with metastatic disease, reflecting the challenge of treating metastatic disease and highlighting the need for novel treatments.

Purpose. Pulsed volumetric modulated arc therapy (VMAT) was proposed as an advanced treatment that combines the biological benefits of pulsed low dose rate (PLDR) and the dosimetric benefits of the intensity-modulated beams. In our conventional pulsed VMAT technique, a daily fractional dose of 200 cGy is delivered in 10 arcs with 3 min intervals between the arcs. In this study, we are testing the feasibility of pulsed VMAT that omits the need to split into ten arcs and excludes any beam-off gaps. Methods. The study was conducted using computed tomographic images of 24 patients previously treated at our institution with the conventional PLDR technique. Our newly installed Elekta machine has a low dose rate option on the order of 25 MU min-1. PLDR requires an effective dose rate of 6.7 cGy min-1 with attention being paid to the maximum dose received within any point within the target not to exceed 13 cGy min-1. The quality of treatment plans was judged based on dose-volume histograms, isodose distribution, dose conformality to the target, and target dose homogeneity. The dose delivery accuracy was assessed by measurements using the MatriXX Evolution 2D array system. Results. All cases were normalized to cover 95% of the target volume with 100% of the prescription dose. The average conformity index was 1.03 +/- 0.08 while the average homogeneity index was 1.05 +/- 0.02. The maximum reported dose rate at any point within the target was 10.44 cGy min-1. The mean dose rate for all pulsed VMAT plans was 6.88 +/- 0.1 cGy min-1. All cases passed our gamma analysis with an average passing rate of 99.00% +/- 0.48%. Conclusion. The study showed the applicability of planning pulsed VMAT using Eclipse and its successful delivery on our Elekta linac. Pulsed VMAT using the machine's low dose rate mode is more efficient than our previous pulsed VMAT delivery.

Naturally Occurring Radioactive Materials (NORM) contribute to everyone's natural background radiation dose. The technologically advanced activities of the gas and oil sectors produce considerable amounts of radioactive materials as industrial by-products or waste products. The goal of the current study is to estimate the danger of long-term liability to Technologically Enhanced Naturally Occurring Radioactive Materials (TE-NORM) on blood indices, neurotransmitters, oxidative stress markers, and β-amyloid in the cerebral cortex of rats' brains. Twenty adult male albino rats were divided into two equal groups (n = 10): control and irradiated. Irradiated rats were exposed to a total dose of 0.016 Gy of TE-NORM as a whole-body chronic exposure over a period of two months. It should be ''The results showed no significant changes in RBC count, Hb concentration, hematocrit percentage (HCT%), and Mean Corpuscular Hemoglobin Concentration (MCHC). However, there was a significant increase in the Mean Corpuscular Volume of RBCs (MCV) and a significant decrease in cell distribution width (RDW%) compared to the control. Alteration in neurotransmitters is noticeable by a significant increase in glutamic acid and significant decreases in serotonin and dopamine. Increased lipid peroxidation, decreased glutathione content, superoxide dismutase, catalase, and glutathione peroxidase activities indicating oxidative stress were accompanied by increased β-amyloid in the cerebral cortex of rats' brains. The findings of the present study showed that chronic radiation liability has some harmful effects, that may predict the risks of future health problems in occupational radiation exposure in the oil industries. Therefore, the control of exposure and application of sample dosimetry is recommended for health and safety.

Patient-specific quality assurance (QA) using measurement-based techniques has been the standard method used in many institutions as an essential step to ensure the accuracy of the actual treatment. In this work, we studied the use of the trajectory log files in specifying the influence of the linear accelerator multi-leaf collimators (MLC) positional errors in the passing rates of our measurement-based QA. In the study, we analyzed sixty-five QA treatment plan results including plans for head and neck, lungs, pelvises, craniospinal, and total body irradiation. Eclipse treatment planning system with Anisotropic Analytical Algorithm (AAA) dose calculation engine was the system used to generate all of our treatment plans. All plans were delivered on Varian (R) linear accelerator UNIQUE which is equipped with 120 Millennium MLC. Trajectory log files generated during treatment delivery were analyzed by a software developed using MATLAB. We compared the planned versus the actual delivered fluence from the recorded log files. Direct subtraction of both fluences allowed us to calculate the degree of match between both fluences. We called it the MLC matching percentage. Measurement-based QAs for all IMRT patients were done using Octavius 4D-PTW dosimetry that incorporates 729 chamber array. The gamma analysis passing rates were calculated by verisoft software using criteria of 3% for dose and 3 mm for distance to agreement and based on the global maximum dose of calculation volume and suppressing the dose blow of 5% of maximum dose of the calculated volume. Then we tested the correlation between the QA passing rate with the related MLC matching percentage. The gamma analysis passing rate was in the range of 90%-99.1% and the matching percentage ranged from 89% to 98.8%. The assessment of the correlation between the gamma passing rate and the matching percentage showed 0.45 correlation coefficient. The p-value was less than 0.05 which indicates a statistically significant correlation. The effect size was on the order of 0.7. Trajectory log file analysis combined with the measurement-based patient specific QA is beneficial to our IMRT QA process and it could be an aid to detect the actual delivery error and hence could improve our passing rates in the future.

I troduction : In this study ,we investigate the feasibility of using Stereotactic radiotherapy (SBRT)Based on Linear accelerator as an alternative to Brachytherapy) BT (for cervical cancer when BT cannot be performed. Twenty patients diagnosed with locally advanced cervical cancer were included in the study .Each patient underwent a treatment regimen consisting of external beam radiotherapy )EBRT (combined with chemotherapy ,followed by an intracavitary high-dose-rate) HDR( brachytherapy) BT (boost .For dosimetric Purposes ,two treatment plans were developed using different treatment techniques ,with the first plan utilizing BT on the Oncentra Treatment Planning System) TPS (and the second plan employing SBRT on the Monaco TPS .The dose constraints utilized for brachytherapy were derived from the EMBRACE II trial ,while those for stereotactic body radiation therapy) SBRT (in four fractions were employed for comparison purposes .A comparative analysis of the dose distribution ,maximum dose points on target volumes ,bladder and rectum ,and dose-volume histograms was conducted between the two techniques.The proximity of organs at risk was assessed to evaluate potential treatment-related adverse effects. In regard to the target D100% and D98% the variation in the two planning techniques was significantly better (p value <0.0005) in favor of the SBRT technique. In regard to critical organ doses, SBRT has shown better sparing for many metrics. For example, D2cc was 22.86 ± 3.65 vs 25.61 ± 3.83 Gray (Gy) for the bladder and for D1cc was 24.34 ± 4.02 vs 28.39 ± 4.49 Gy, while no significant difference resulted regarding D5cc. In addition, there was a significant difference between D2cc and D1cc for the sigmoid, also there was a significant difference for the maximum dose for the left and right head of femurs (p< 0.005) all in favor of SBRT. In regard of D2cc and D1cc for the rectum there was a significant difference (P <0.005) both in favor of SBRT. However, for D5cc there is no significant difference between the two techniques. The study found that SBRT is effective and safe for treating cervical cancer when brachytherapy is not possible. However, the movement of organs and potential low doses to other structures should be considered. Further research is necessary to optimize SBRT for cervical cancer treatment.

Radiation-induced radicals in the crystals of strontium sulfate (SS) as rod dosimeters were studied using an electron paramagnetic resonance (EPR) spectrometer. Dosimetric studies were performed in the dose range of 0.5 to 25 Gy for the dosimeters to investigate their potential applications in radiotherapy (60Co gamma-rays and high megavoltage X-ray with 6 and 15 MV). Additionally, the response of these dosimeters was compared to the response of alanine pellet dosimeters at the three-beam qualities. Irradiation of SS dosimeters produces five EPR signals, and their intensity increases linearly with increasing absorbed doses from 0.5 to 25 Gy. A peak of a splitting g-factor (g) = 2.01039 was selected for the present evaluations as it has a higher intensity. The change in response of SS rod dosimeters after irradiation does not exceed +/- 2% over six months, exhibiting good stability. The response of SS dosimeters increases with increasing the incident beam energy from 60Co gamma rays to 16 MV X-ray beam. For alanine dosimeters, a non-significant change is observed under these beam qualities. The response of SS dosimeter at 6 and 15 MV relative to a60Co beam quality increases by about 3.8% and 14.1%, respectively. Moreover, the response of the SS dosimeters increases 2.24% with increasing the dose rate from 100 to 400 cGy/min, while for the alanine dosimeters, the increase in response is less than 0.49%. Environmental factors (relative humidity levels of 0-76% and temperature degrees of 15-30 degrees C) have a slight impact on the response of SS rods during irradiation. The overall uncertainty of dose monitoring was reported to be +/- 4.02% (20, 95% confidence levels).

The technologically advanced activities of the gas and oil sectors produce a considerable amount of naturally occurring radioactive materials (NORM) as industrial by-products or waste products. The goal of the current study is to estimate the danger of long-term liability to Technologically Enhanced Naturally Occurring Radioactive Materials (TE-NORM) on the cerebral cortex of rats’ brains. A high purity germanium ɣ-ray spectrometer was used to assess the radioactivity of samples. 20 Adult male Albino rats were used in the current experiment. The animals were divided into two groups: a control group and an irradiated group. Each rat in the irradiated group received a total dose of 0.016 Gy of TE-NORM as a chronic radiation exposure over a whole two months. Rats were then sacrificed. Some hematological and neurotransmitter parameters, as well as oxidative stress and β-amyloid, were evaluated. The disturbance was found in all parameters due to chronic ionizing radiation exposure. The results showed that two months of whole-body exposure to chronic ionizing radiation with a total dose of 0.016 Gy of TE-NORM induced significant changes in hematological, neurotransmitter, and oxidative stress parameters and increased the β-amyloid concentration in the cerebral cortex of rats' brains. The findings of the present study showed that chronic radiation liability has some harmful effects.

The objective of the present study is to understand the effect of chronic low-dose radiation that induces in vivo radio-adaptive response. The animals were exposed chronically to naturally occring radioactive materials (NORM) for one and two months which correspond to 10 &20 mSv which are comparable to the reality of areas with high background natural radiation (HBNR). Radioactivity assessment of samples was performed using a high purity germanium gamma-ray spectrometer. The study to understand the radio-adaptive response was conducted via exposing the experimental animals to a challenge dose of 2 Gy, after continuous exposure to 10 & 20 mSv. Comet assay was performed in addition to some of antioxidant enzymes concentrations (superoxide dismutase (SOD), catalyze enzyme (CAT), reduced and oxidized glutathione (GSH). Chronic exposure to 10 and 20 mSv showed DNA damage as a significant elevation in Comet assay parameters. In addition, the results of the present work showed a low production of antioxidant enzymes CAT, SOD & GSH in both chronic exposures (10 & 20 mSv and challange dose 2 Gy). The exposure to 20 mSv before 2Gy gamma rays resulted in an enhancement of the antioxidant enzymes accompanied with a decrease in free radicals which represent an adaptive response. It can be said that for low radiation doses, which are less than 100 mSv, their effects differ from high doses, so that it can be said that the body has an adaptive response and the application of the linear nonthreshold model must be reviewed for these doses.

Treatment planning systems play a key role in radiotherapy. Various commercial planning systems are currently available on the market. These systems usually differ in the algorithms used for radiation dose calculation and vary in the manner of implementation of the same algorithms. They also differ in optimizer algorithms used in search of the best treatment plan required to meet the user specified criteria. In this study, we evaluate two optimization systems available from two commercial treatment planning systems. The two systems used in the study are the Eclipse Planning System (version 10.042, Varian Medical Systems, Palo Alto); and, Monaco Planning System (version 3.01, Elekta CMS Software, St. Louis, MO). Computed tomographic images for ten patients, previously planned using Eclipse, were randomly selected from our patient database. We generated treatment plans for the ten cases utilizing the Monaco system. Monaco utilizes a set of biological and DVH functions in the optimization process, while Eclipse uses only dose volume objectives. Planners would need to understand the difference between the two methodologies for getting better outcomes in radiation treatment planning for cancer patients. All generated plans in the study were evaluated based on dose volume histogram (DVH) and isodose distributions. The overall performance of dose volume optimization was better compared to the biological optimization. Dose volume optimization was more efficient and easier to manipulate for our prostate cases. The biological optimization process provided good quality plans. However, the optimizer requires improvement to become more efficient.

Gamma-ray stereotactic radiosurgery systems available commercially contain either stationary or rotational source configuration. Rotational systems reduce the number of sources utilized and can also provide beneficial dosimetric properties. In this study, we explore the dosimetric advantage of a novel rotating gamma-ray design for stereotactic body radiotherapy (SBRT) as compared to the well-established CyberKnife system. CybeRay (OUR United Corp., Xian, China) is a rotating gamma-ray system (RGS). Its treatment head can rotate 360° in the axial plane and swing 35° in the superior direction. It includes 13 Co-60 sources focusing on the isocenter. The RT Pro planning system (Prowess, Concord, CA) was used for CybeRay treatment planning, while the Multiplan software (Accuray, Sunnyvale, CA) was used for CyberKnife treatment planning. Twelve SBRT patients previously treated with CyberKnife were re-planned for CybeRay, and their treatment plans were compared based on isodose distributions, dose volume histograms, conformity index (CI), and the estimated treatment time. The planning target volume ranged from 4.4 to 124.2 cc. Both treatment systems provided excellent SBRT plans that meet our clinical acceptance criteria. The mean value of CI was 1.25 for both CyberKnife and CybeRay (p = 0.03). The estimated treatment delivery time for the CyberKnife plans ranged from 13 to 53 min as compared to 6 to 54 min with CybeRay (p = 0.02). CybeRay was superior concerning peripheral doses appearing as excessive isodose lines extending to distal normal tissues. The new CybeRay machine showed promising dosimetric capabilities for stereotactic radiosurgery and radiotherapy of extra- and intra-cranial lesions.

A large amount of naturally occurring radioactive materials (NORM) is produced by the technological enhanced activities of gas and oil industries as by-products or waste. The present study aims to estimate the risk of chronic exposure to the Technological Enhanced Naturally Occurring Radioactive Materials (TE-NORM) and its radio-adaptive response before exposure to 2Gy single dose on male rats. The electrical properties of blood (conductivity and conductance) were measured. In addition to the Electron Para-magnetic Resonance (EPR) technique was used to estimate the free radical in blood, some hematological parameters and lipid peroxidation (MDA) were determined. Six groups of adult male rats were classified according to the period of TE-NORM exposure. All irradiated groups showed increase in Red blood cells Distribution Width (RDW), membrane conductivity, capacitance, EPR intensity and lipid peroxides. However, TE-NORM exposure for two months before 2 Gy exposure reduced the EPR intensity and lipid peroxidation when compared to 2Gy group. The results of this study demonstrated that chronic radiation exposure has some deleterious effects as it appeared in EPR and lipid peroxides elevation, while it showed radio-adaptive response as noticed in TE-NORM for two months before 2Gy group. It could be postulated that radio-adaptive response occurs especially for longer period of chronic exposure before irradiation with a single high dose.

Purpose: To explore whether radiomic features of fluorine-18-fluorodeoxyglucose (F-18-FDG) positron emission tomography-computed tomography (PET/CT) has association with bone marrow infiltration (BMI) in comparison to other conventional PET metrics. Material and methods: Forty-four patients (with pathologically proven lymphoma disease) underwent staging F-18-FDG PET/CT scan. Primary tumour was semi-automatically or manually segmented with a threshold standardised uptake value (SUV) of 3. A total of 73 features were extracted from eight different textures. Spearman correlation was used to test the correlation of features with conventional quantitative metrics such as SUV, metabolic tumour volume, and total lesion glycolysis. Specificity and sensitivity (including 95% confidence intervals [CI]) for each of the studied parameters were derived using receiver operative characteristic (ROC) curves. Univariate and multivariate analyses were used to identify independent predictors associated with BMI. Results: Correlation between conventional PET metrics and features ranged between 0.50 and 0.97 for positive correlation (33 significant association features) and ranged from -0.52 to -0.97 for inverse correlation (three significant association features) for both strong and moderate correlations. Analysis of ROC curves showed that high-intensity long-run emphasis 4 bin, high-intensity large zone emphasis 64 bin, long- run emphasis (LRE) 64 bin, large-zone emphasis 64 bin, max spectrum 8 bin, busyness 64 bin, and code similarity 32 and 64 bin were significant discriminators of BMI among other features (area under curve > 0.682, p < 0.05). Univariate analyses of texture features showed that code similarity and long-run emphasis (both 64 bin) were significant predictors of bone marrow involvement. Multivariate analyses revealed that LRE (64 bin, p = 0.031) with an odds ratio of 1.022 and 95% CI of (1.002-1.043) were independent variables for bone marrow involvement. Conclusions: F-18-FDG PET/CT radiomic features are synergistic to visual assessment of BMI in patients diagnosed with lymphoma using F-18-FDG PET/CT. Further assessment of long-run emphasis is highly warranted.

Purpose. To explore the ability of image-based parameters with texture parameters in the differentiation of bone marrow infiltration by positron emission tomography-computed tomography (PET/CT). Procedures. We retrospectively evaluated the baseline PET/CT scan of 44 patients with histologically proven lymphoma. Seventy-three of features were extracted using CGITA software and statistical analysis were carried out on SPSS program. Results. Spearman correlation analysis revealed a strong positive correlation between conventional PET metrics and texture features (19 significant association features) and inverse correlation was found (one parameter significant association feature). Area under the curve and p-value of receive operating characteristics showed that (HILRE (4-bin), HILZE (64-bin), LRE (64-bin), LZE (64-bin), max spectrum (8-bin), busyness (64-bin),code similarity (32-bin & 64-bin)) were significant discriminator of bone marrow infiltration among other features (AUC>0.682, p < 0.05). Univariate analyses of texture features showed that code similarity and LRE (both 64 bin) has significant prediction to BMI. Multivariate analyses revealed that LRE (64 bin) p= 0.031; odds ratio: 1.022; 95% CI, 1.002-1.043) were independent variables for bone marrow infiltration. Conclusions. Significant associations emerged between PET features and bone marrow infiltration in lymphoma. Texture analysis on PET/CT shows potential to differentiate between bone marrow infiltration in patients with Lymphoma.