Additional Radiation Research Articles

The decision to reimage following extravasation in diagnostic nuclear medicine.

The primary goal of diagnostic nuclear medicine is to provide complete and accurate reports without equivocation or disclaimers. If specific clinical questions cannot be answered because of radiopharmaceutical extravasation, the imaging study may have to be repeated. The decision to reimage is based on several factors including the diagnostic quality of the images, additional patient radiation dose, patient burden, and administrative constraints. Through process improvement efforts, nuclear medicine departments can significantly reduce the frequency of extravasation and thereby also the need for reimaging. Communication with the patient is important any time extravasation may impact their immediate or future care. The circumstances and potential ramifications should be explained, and patient concerns should be addressed. Although recent arguments have been made in favor of investigating and addressing only those extravasations which result in serious patient injury, patients and their referring physicians deserve to know any time their nuclear medicine study may have been impacted.

Review of clinical applications and challenges with surface-guided radiation therapy.

To evaluate the use of this new technique, surface-guided radiotherapy (SGRT), for patient setup and motion management in various cancers. Data was collected from 533 patients, who received treatment in our hospital for various malignancies using SGRT from October 2019 to April 2021. We studied patient setup, interfraction position, and patient position during the breath-hold (BH) technique. The main advantage of SGRT is that, it is completely non-invasive and uses visible light to compare the patient's skin surface in the treatment room and planned treatment position. In this analysis, Monaco 5.51.10 (Elekta) treatment planning system, Versa HD Linear Accelerator, and AlignRT 6.2 (Vision RT) SGRT system were used. With SGRT, treatment setup time can be reduced with more precision and techniques like Deep inspiration breathhold (DIBH) can be done with very good compliance. SGRT has shown improved accuracy in patient setup compared to conventional laser setup. The daily kilo voltage imaging frequency can be reduced; it helps in reducing additional radiation exposure due to imaging. SGRT has demonstrated reproducibility with adequate accuracy in BH treatments in DIBH for breast and SBRT.

Second-line treatment of pediatric patients with relapsed rhabdomyosarcoma adapted to initial risk stratification: Data of the European Soft Tissue Sarcoma Registry (SoTiSaR).

Outcome of relapsed disease of localized rhabdomyosarcoma remains poor. An individual treatment approach considering the initial systemic treatment and risk group was included in the Cooperative Weichteilsarkom Studiengruppe (CWS) Guidance. Second-line chemotherapy (sCHT) ACCTTIVE based on anthracyclines (adriamycin, carboplatin, cyclophosphamide, topotecan, vincristine, etoposide) was recommended for patients with initial low- (LR), standard- (SR), and high-risk (HR) group after initial treatment without anthracyclines. TECC (topotecan, etoposide, carboplatin, cyclophosphamide) was recommended after initial anthracycline-based regimen in the very high-risk (VHR) group. Data of patients with relapse (n=68) registered in the European Soft Tissue Sarcoma Registry SoTiSaR (2009-2018) were retrospectively analyzed. Patients of initial LR (n=2), SR (n=16), HR (n=41), and VHR (n=9) group relapsed. sCHT consisted of ACCTTIVE (n=36), TECC (n=12), or other (n=15). Resection was performed in 40/68 (59%) patients and/or radiotherapy in 47/68 (69%). Initial risk stratification, pattern/time to relapse, and achievement of second complete remission were significant prognostic factors. Microscopically incomplete resection with additional radiotherapy was not inferior to microscopically complete resection (p=.17). The 5-year event-free survival (EFS) and overall survival (OS) were 26% (±12%) and 31% (±14%). The 5-year OS of patients with relapse of SR, HR, and VHR groups was 80% (±21%), 20% (±16%), and 13% (±23%, p=.008), respectively. Adapted systemic treatment of relapsed disease considering the initial risk group and initial treatment is reasonable. New treatment options are needed for patients of initial HR and VHR groups.

Establishment and validation of nomograms to predict survival probability of advanced malignant pleural mesothelioma based on the SEER database and a Chinese medical institution.

The purpose of this study was to build nomograms for predicting the survival of individual advanced pleural mesothelioma (MPM) patients using the Surveillance, Epidemiology, and End Results (SEER) database. The 1251 patients enrolled from the SEER database were randomized (in a 7:3 ratio) to a training cohort and an internal validation cohort. Eighty patients were enrolled from the Harbin Medical University Cancer Hospital as the external validation cohort. Nomograms were constructed from variables screened by univariate or multivariate Cox regression analyses and evaluated by consistency indices (C-index), calibration plots, and receiver operating characteristic (ROC) curves. Patients from the SEER database who received chemotherapy alone and chemoradiotherapy were statistically paired using propensity score matching of the two groups and performed subgroup analysis in the screened variables. The nomograms are well-structured and well-validated prognostic maps constructed from four variables: gender, histology, AJCC stage, and treatment. All individuals were allocated into high-risk versus low-risk groups based on the median risk score of the training cohort, with the high-risk group having worse OS and CSS in all three cohorts (P<0.05). The outcomes of the subgroup analysis indicated that the advanced MPM patients receiving chemotherapy with or without local radiotherapy do not affect OS or CSS. The accurate nomograms to predict the survival of patients with advanced MPM were built and validated based on an analysis of the SEER database with an external validation cohort. The study suggests that the additional local radiotherapy to chemotherapy does not increase the survival benefit of patients.

The Revised R Status is an Independent Predictor of Postresection Survival in Pancreatic Cancer After Neoadjuvant Treatment.

To investigate the oncological outcomes of patients with pancreatic ductal adenocarcinoma (PDAC) who had an R 0 or R 1 resection based on the revised R status (1mm) after neoadjuvant therapy (NAT). The revised R status is an independent prognostic factor in upfront-resected PDAC; however, the significance of 1mm margin clearance after NAT remains controversial. Patients undergoing pancreatectomy after NAT for PDAC were identified from 2 prospectively maintained databases. Clinicopathological and survival data were analyzed. The primary outcomes were overall survival (OS), recurrence-free survival (RFS), and pattern of recurrence in association with R 0 >1mm and R 1 ≤1mm resections. Three hundred fifty-seven patients with PDAC were included after NAT and subsequent pancreatic resection. Two hundred eight patients (58.3%) received FOLFIRINOX, 41 patients (11.5%) received gemcitabine-based regimens, and 299 individuals (83.8%) received additional radiotherapy. R 0 resections were achieved in 272 patients (76.2%) and 85 patients (23.8%) had R 1 resections. Median OS after R 0 was 41.0 months, compared with 20.6 months after R 1 resection ( P = 0.002), and even longer after additional adjuvant chemotherapy ( R 0 44.8 vs R1 20.1 months; P = 0.0032). Median RFS in the R 0 subgroup was 17.5 months versus 9.4 months in the R 1 subgroup ( P < 0.0001). R status was confirmed as an independent predictor for OS ( R 1 hazard ratio: 1.56, 95% CI: 1.07-2.26) and RFS ( R 1 hazard ratio: 1.52; 95% CI: 1.14-2.0). In addition, R 1 resections were significantly associated with local but not distant recurrence ( P < 0.0005). The revised R status is an independent predictor of postresection survival and local recurrence in PDAC after NAT. Achieving R 0 resection with a margin of at least 1mm should be a primary goal in the surgical treatment of PDAC after NAT.

Clinicopathological and molecular genetic characteristics of primary gastric follicular lymphoma

Primary gastric follicular lymphomas (FLs) have been rarely reported, and little is known about their characteristics. In the present study, we report 5 cases of primary gastric FL and describe their clinicopathological and molecular genetic features. A total of 7 samples from 5 patients were investigated for clinicopathological characteristics and somatic mutations by the targeted sequencing of 50 lymphoma-related genes. Two cases were identified as slightly elevated submucosal tumors and 3 cases as polypoid tumors. Histologically, all cases were low-grade FLs. The immunoprofile was CD20+/CD10+/BCL2+ in 4 cases and CD20+/CD10+/BCL2- in 1 case. The immunostaining pattern for CD21 was similar to that of classic FL. BCL2 rearrangement was not identified in fluorescence in situ hybridization studies in any of the 5 cases. Next-generation sequencing analysis showed mutations in genes involved in epigenetic modifications (KMT2D, ARID1A, EP300, and CREBBP), NK-kB pathway (CARD11), and JAK-STAT pathway as found in classic FL. All cases presented with clinical I without the involvement of regional or systemic lymph nodes. Four patients were well, whereas 1 patient who received endoscopic mucosal resection of tumor without additional chemotherapy or radiotherapy experienced 3 relapses. In conclusion, primary gastric FL is characterized by a low-grade neoplasm with infrequent BCL2 rearrangement. After resection of the lesion, additional treatment such as radiation therapy or chemotherapy is required as there is a possibility of recurrence.

Primary non-Hodgkin's lymphoma of the superficial branch of the radial nerve: illustrative case.

Lesions of the peripheral nervous system are many and varied. They range from benign to malignant, and determining risk can be challenging. Primary lymphoma of the peripheral nerve (PLPN) is a rare and malignant pathology. When recognized early, appropriate therapy can be delivered. The authors performed a systematic review of PLPNs and present the first case of a PLPN involving the superficial branch of the radial nerve. The authors present the clinical presentation and radiological features of a rare case of primary non-Hodgkin's lymphoma of the superficial branch of the radial nerve. Following gross-total resection, the patient received adjuvant chemotherapy and was free of disease at the last follow-up. With astute observation, less common and sinister peripheral nerve lesions can be recognized at an early stage and tend to be associated with a relatively short history of peripheral sensorimotor deficits and subtle radiographic changes. In such a setting, consideration should be given to performing a biopsy rather than gross-total resection, indeed sparing the parent nerve and facilitating diagnosis. Definitive treatment for PLPN is chemotherapy with the addition of radiotherapy in some circumstances.

Stack cooling system coupled with secondary heat pump in fuel cell electric vehicles

Fuel cell electric vehicles (FCEVs) requires proper thermal management of a proton-exchange membrane fuel cell (PEMFC) stack, but conventional thermal management systems (TMSs) cannot manage the thermal requirements of PEMFCs under high-power density at high ambient temperatures. In this study, a stack cooling system coupled with a secondary heat pump in an FCEV is suggested. The enhanced thermal flexibility of the secondary heat pump system enabled extensive cooling with various TMS configurations. The cooling performance with different TMS configurations was evaluated, considering the thermal and electrical coupling of the heat pump system and the PEMFC stack. The results show that the stack temperature was lowered up to 2.6 °C when the excessive cooling load of the stack radiator was distributed to the cabin radiator under a relatively low-power output condition. To dissipate a large amount of waste heat from the stack, TMS requires a temporary shutdown of the cabin cooling system. In this case, utilizing the inactive outdoor heat exchanger as an additional radiator decreased the temperature up to 18.4 °C by extending the heat transfer area for stack cooling. This study proposes a cooling scheme for an FCEV and suggests appropriate cooling methods and configurations under various operating conditions.

Opportunistic screening for osteoporosis by abdominal CT in a British population

BackgroundIt has previously been shown that CT scans performed for other indications can be used to identify patients with osteoporosis. This has not yet been tested in a British population. We sought to evaluate the use of vertebral CT attenuation measures for predicting osteoporosis in a British cohort, using dual-energy X-ray absorptiometry (DEXA) as a reference standard.MethodsPatients who underwent abdominal CT in 2018 and concomitantly underwent DEXA within a six-month interval were retrospectively included. CT attenuation values in Hounsfield units (HU) were measured by placement of a region-of-interest at the central portion of the L1 vertebral body and then compared to their corresponding DEXA score. Receiver operating characteristic (ROC) curves were generated to evaluate the performance of a logistic regression model and to determine sensitivity and specificity thresholds.Results536 patients (394 females, mean age 65.8) were included, of which 174 had DEXA-defined osteoporosis. L1 attenuation measures were significantly different (p < 0.01) between the three DEXA-defined groups of osteoporosis (118 HU), osteopenia (143 HU) and normal bone density (178 HU). The area under the ROC curve was 0.74 (95% CI 0.69–0.78). A threshold of 169 HU was 90% sensitive, and a threshold of 104 HU was 90% specific for diagnosing osteoporosis.ConclusionsRoutine abdominal CT can be used to opportunistically screen for osteoporosis without additional cost or radiation exposure. The thresholds identified in this study are comparable with previous studies in other populations. We recommend radiologists engage with primary care and rheumatology providers to determine appropriate cut-off values for further investigation.

Imaging doses for different CBCT protocols on the Halcyon 3.0 linear accelerator – TLD measurements in an anthropomorphic phantom

IntroductionImage guided radiotherapy allows for particularly conformal tumour irradiation through precise patient positioning. Becoming the standard for radiotherapy, this increases imaging doses to the patient. The Halcyon 3.0 linear accelerator (Varian Medical Systems, Palo Alto, CA) requires daily imaging due to its geometry. For this reason, the accelerator is equipped with on-line kV and MV imaging. However, daily CBCT images required for irradiation apply additional radiation, which increases the dose to normal tissue and therefore can affect the patient's secondary cancer risk. In this study, actual organ doses were measured for the kV system, and a comparison of normal tissue doses for all available kV CBCT protocols was presented to demonstrate differences in imaging doses across entities and protocols. In addition, effective dose and secondary cancer risk from imaging are evaluated. Material and methodsMeasurements were performed with thermoluminescent dosimeters in an anthropomorphic phantom positioned according to each entity (brain, head and neck, breast, lung, pelvis). CBCT images were obtained, using all available pre-set protocols without further adjustment of the parameters. Measured doses for each position and each protocol were then compared and secondary cancer risk of relevant and specifically radiosensitive organs was calculated. ResultsIt was found that imaging doses for protocols such as Pelvis and Head could be reduced by up to half using the corresponding Fast and Low Dose modes, respectively. On the other hand, larger field sizes or the Large mode yielded higher doses than their initial protocols. Image Gently was found to spare normal tissue best, however it is not suitable for certain entities due to low image quality or insufficient projection data. DiscussionBy using appropriate kV-CBCT protocols, it is possible to reduce imaging doses to a significant extent and therefore spare healthy tissue. Combined with studies of image quality, the results of this study could lead to adjustments in workflow regarding the choice of protocols used in daily routine. This could prevent unnecessary radiation exposure and reduce secondary cancer risk.

Wideband Series-Fed Microstrip Patch Antenna Array With Flat Gain Based on Magnetic Current Feeding Technology

A series-fed microstrip patch antenna array with broad bandwidth and flat gain based on magnetic current feeding structure is presented in this letter. By appropriately blocking the microstrip line, a radiation mode of the microstrip structure is generated, which is equivalent to the magnetic current array. Also, the magnetic current is used to excite the sides-shorted microstrip patch antennas via coupling slots. The broad operation bandwidth of the series-fed array is achieved by merging the fundamental mode generated from the sides-shorted microstrip patch antenna element and the additional radiation mode from the microstrip feeding structure. Moreover, dual radiators are employed in the design to ensure that the gain remains flat. Based on the proposed idea, a 6-element linear array with a center feed is implemented and tested. The results indicate that a wide impedance bandwidth of 9.11–11.84 GHz (26.1%) and a 1 dB gain bandwidth of 9.1–11.5 GHz (23.3%) is achieved, with a maximum gain of 13.95 dBi.

Attention fusion network with self-supervised learning for staging of osteonecrosis of the femoral head (ONFH) using multiple MR protocols.

Osteonecrosis of the femoral head (ONFH) is characterized as bone cell death in the hip joint, involving a severe pain in the groin. The staging of ONFH is commonly based on Magnetic resonance imaging and computed tomography (CT), which are important for establishing effective treatment plans. There have been some attempts to automate ONFH staging using deep learning, but few of them used only MRimages. To propose a deep learning model for MR-only ONFH staging, which can reduce additional cost and radiation exposure from the acquisition of CTimages. We integrated information from the MR images of five different imaging protocols by a newly proposed attention fusion method, which was composed of intra-modality attention and inter-modality attention. In addition, a self-supervised learning was used to learn deep representations from a large amount of paired MR-CT dataset. The encoder part of the MR-CT translation network was used as a pretraining network for the staging, which aimed to overcome the lack of annotated data for staging. Ablation studies were performed to investigate the contributions of each proposed method. The area under the receiver operating characteristic curve (AUROC) was used to evaluate the performance of thenetworks. Our model improved the performance of the four-way classification of the association research circulation osseous (ARCO) stage using MR images of the multiple protocols by 6.8%p in AUROC over a plain VGG network. Each proposed method increased the performance by 4.7%p (self-supervised learning) and 2.6%p (attention fusion) in AUROC, which was demonstrated by the ablationexperiments. We have shown the feasibility of the MR-only ONFH staging by using self-supervised learning and attention fusion. A large amount of paired MR-CT data in hospitals can be used to further improve the performance of the staging, and the proposed method has potential to be used in the diagnosis of various diseases that require staging from multiple MRprotocols.

Benefits of Reducing Incision Tension in Hard-To-Close Keloid Surgery.

Benefits of Reducing Incision Tension in Hard-To-Close Keloid Surgery.

Outcome of Operated Colorectal Cancers in Relation to the Type of Initial Referral.

Aim Since the introduction of the target referral system, there has been controversy about its value and whether it affected the short- and long-term outcomes of colorectal cancer surgeries. With contradicting results, this study highlights differences in personal and tumour characteristics, management differences, and outcomes in each referral pathway, including target pathway referrals for suspected cancers, emergency presentations, routine referrals, and incidentally discovered cancers during screening. Methods A retrospective study of colorectal cancer (CRC) patients operated on between January 1, 2010, and December 31, 2014, with records dating to the end of the five-year follow-up, was extracted anonymously from the database of CRC outcomes at the North Middlesex University Hospital NHS Trust, London. The total number of patients operated on through the four pathways was 176, with full records and competent follow-ups. Patients were classified according to the mode of referral: two-week wait (2WW or target), routine, emergency, and incidental discovery referrals. Comparisons were made between these groups with regard to personal and tumour characteristics, management, and outcome. Results It has been demonstrated by this study that targetreferrals present mainly with stage I cancers as compared to emergency referrals that present with more stage II (IIa+ IIb+ IIc). The highest percentage of cancer locations within the large bowel was rectal, followed by sigmoid in both target and emergency groups; 8.8% of target patients needed neoadjuvant chemoradiotherapy in the form of FOLFOX (folinic acid, 5-fluorouracil, and oxaliplatin) chemotherapy protocol with the addition of radiotherapy in patients with advanced rectal cancers, compared to 13.3% of emergency patients. Conclusion The colorectal 2WW system was the main pathway supplying colorectal cancer operations; it mostly showed earlier cancers than the other referral groups; its cancers were mostly rectosigmoid with less need for adjuvant chemotherapy; fewer recurrences; and it also showed a lower five-year mortality rate than the emergency group.

Deep Learning-Based Automated Quantification of Coronary Artery Calcification for Contrast-Enhanced Coronary Computed Tomographic Angiography.

We evaluated the accuracy of a deep learning-based automated quantification algorithm for coronary artery calcium (CAC) based on enhanced ECG-gated coronary CT angiography (CCTA) with dedicated coronary calcium scoring CT (CSCT) as the reference. This retrospective study included 315 patients who underwent CSCT and CCTA on the same day, with 200 in the internal and 115 in the external validation sets. The calcium volume and Agatston scores were calculated using both the automated algorithm in CCTA and the conventional method in CSCT. The time required for computing calcium scores using the automated algorithm was also evaluated. Our automated algorithm extracted CACs in less than five minutes on average with a failure rate of 1.3%. The volume and Agatston scores by the model showed high agreement with those from CSCT with concordance correlation coefficients of 0.90-0.97 for the internal and 0.76-0.94 for the external. The accuracy for classification was 92% with a 0.94 weighted kappa for the internal and 86% with a 0.91 weighted kappa for the external set. The deep learning-based and fully automated algorithm efficiently extracted CACs from CCTA and reliably assigned categorical classification for Agatston scores without additional radiation exposure.

Medium-induced radiation with vacuum propagation in the pre-hydrodynamics phase

The recent discovery of the potential of jet quenching observables to constrain the initial stages after a heavy-ion collision makes imperative to have a better understanding of the process of medium-induced radiation before the formation of the quark-gluon plasma (QGP) and its impact on observables at high-pT. In this work, we generalize the BDMPS-Z framework for medium-induced radiation to account for additional emissions occurring before the creation of the QGP. For simplicity, we assume that during the pre-hydrodynamics phase the hard parton propagates as in vacuum. This set-up, allows us to isolate the contribution from the additional initial radiation by comparing with the usual scenarios in which the emitter is created inside the medium but with different starting points. Using both a numerical implementation of the fully resummed emission spectrum and the usual analytical approximations, we find that replacing an initial slab of the medium by vacuum yields to a significant reduction of the emission spectrum for low radiated gluon energies, while the high-energy tails remain largely unmodified. Finally, we assess the effect of replacing the initial medium by vacuum propagation on the single-inclusive particle suppression RAA and high-pT azimuthal asymmetry v2. Our findings indicate that considering vacuum propagation prior to hydrodynamization leads to an increase in the v2, thus corroborating the importance of the treatment of jet quenching in the initial stages for the correct description of both observables.

Quantitative MRI to Characterize Hypoxic Tumors in Comparison to FMISO PET/CT for Radiotherapy in Oropharynx Cancers

Intratumoral hypoxia is associated with a poor prognosis and poor response to treatment in head and neck cancers. Its identification would allow for increasing the radiation dose to hypoxic tumor subvolumes. 18F-FMISO PET imaging is the gold standard; however, quantitative multiparametric MRI could show the presence of intratumoral hypoxia. Thus, 16 patients were prospectively included and underwent 18F-FDG PET/CT, 18F-FMISO PET/CT, and multiparametric quantitative MRI (DCE, diffusion and relaxometry T1 and T2 techniques) in the same position before treatment. PET and MRI sub-volumes were segmented and classified as hypoxic or non-hypoxic volumes to compare quantitative MRI parameters between normoxic and hypoxic volumes. In total, 13 patients had hypoxic lesions. The Dice, Jaccard, and overlap fraction similarity indices were 0.43, 0.28, and 0.71, respectively, between the FDG PET and MRI-measured lesion volumes, showing that the FDG PET tumor volume is partially contained within the MRI tumor volume. The results showed significant differences in the parameters of SUV in FDG and FMISO PET between patients with and without measurable hypoxic lesions. The quantitative MRI parameters of ADC, T1 max mapping and T2 max mapping were different between hypoxic and normoxic subvolumes. Quantitative MRI, based on free water diffusion and T1 and T2 mapping, seems to be able to identify intra-tumoral hypoxic sub-volumes for additional radiotherapy doses.

Reducing radiation exposure and cancer risk for children with scoliosis: EOS the new gold standard

PurposeChildren are exposed to significant radiation doses during the investigation and treatment phases of scoliosis. EOS is a new form of low-dose radiation scan which also yields great image quality. However, currently its use is discouraged in the UK due to higher costs. We aimed to quantify the additional radiation dose and cancer risk.MethodsWe retrospectively reviewed all paediatric cases who received both standing whole spine roentgenograms and EOS scans as part of their investigations for scoliosis during a six-month period. We compared the radiation doses between the two modalities and estimated the additional mean lifetime cancer risk per study.ResultsWe identified 206 children (mean age 14.4) who met the criteria of having both scans. Dose area products (dGycm2) were converted to estimated effective doses (mSv). The total mean doses were 0.68 mSv (PA 0.49 + Lat 0.19) for plain films, and 0.13 mSv (PA 0.08 + Lat 0.04) for EOS scans (p < 0.001). Additional lifetime cancer risk of a plain film was 543% greater than EOS for both sexes (1/10727 versus 1/5827 in males, 1/34483 versus 1/6350 in females).ConclusionThere is approximately 5.4-fold increase in risk of cancer for both boys and girls with roentgenograms over EOS, with girls being the most impacted. This carries a significant impact when considering the need for repeat imaging on additional lifetime malignancy risk in children. In our opinion, EOS dual planar scanning is the new gold standard when X-ray of the whole spine is required.Level of evidence III.

Solid-oil separation of coal tar residue to reduce polycyclic aromatic hydrocarbons via microwave-assisted extraction

Coal tar residue (CTR) is acknowledged as hazardous industrial waste with high contents of carbon and toxic polycyclic aromatic hydrocarbons (PAHs). Microwave-assisted extraction for separating tar and residue in CTR was investigated to reduce the content of PAHs. The key operating factors such as solvent type, solvent addition amount, radiation temperature, and radiation time in the extraction process were evaluated. Results showed that extreme extraction performance in the solvent with cyclic structure was attained, and an enhancement in extraction efficiency was achieved in elevated solvent addition amount, radiation temperature, or radiation time in a certain range. The optimized conditions were determined as benzene was chosen as extractant, solvent-solid ratio of 5:1 mL/g, radiation temperature of 75 °C, and radiation time of 10 min. Relative extraction efficiency of CTR and reduction efficiency of 16 priority control PAHs were 28.70% and 92.82%, respectively. According to the characterizations of extracted residue (MCTR) and tar (MCT) under optimum experimental conditions, it is possible to convert them into value-added products (carbon materials, solid fuels, or chemicals). Solid-oil separation via microwave-assisted extraction is a safe and high-valued utilization approach for CTR.

Comparative Analysis of SAM and RETScreen Tools for the Case Study of 600 kW Solar PV System Installation in Riyadh, Saudi Arabia

In this study, we discussed the main recent studies on PV systems worldwide and specifically in the Gulf Cooperation Council (GCC) region. We focused on different PV cells and their characteristics in terms of efficiency, importance, and negative impacts, and examined the classification of PV systems and their comparison. In addition, the adoption of PV technologies in GCC countries is considered, focusing on the future aspects. In addition, technical and economic evaluations were carried out for a 600-kW commercial PV solar project at one of the selected sites in the Riyadh region, and the PV energy generation performance was assessed. The monthly energy production, module orientation and tracking system, peak voltage, net power consumption, rated output power, cash flow and capacity factor were calculated. In addition, the direct, normal and diffuse solar radiation are calculated to determine the cost-effective and efficient PV system. Two simulation programs, namely system advisor model (SAM) and RETScreen, are used in this study. In addition, a comparison between annual energy production, cash flow, and electricity loads was performed to evaluate the accuracy of the simulation results. The study suggests that a low-cost PV system could be developed in the Riyadh region.