Association of Complications During and After Carotid Body Tumor Resection with Tumor Size and Distance to the Base of Skull.

BACKGROUND: Depending on the size and location of the tumor, carotid body tumor (CBT) resection can come with various complications, mostly intraoperative bleeding, and cranial nerve injuries. In the present study, we aim to evaluate 2 fairly new variables, tumor volume, and distance to the base of the skull (DTBOS), with operative complications of CBT resection. METHODS: Patients who underwent CBT surgery in Namazi hospital from 2015 to 2019 were studied using standard databases. Tumor characteristics and DTBOS were measured via computed tomography or Magnetic resonance imaging. Outcomes, including intraoperative bleeding and cranial nerve injuries, along with perioperative data were collected. RESULTS: A total of 42 cases of CBT were evaluated with an average age of 53.21 ± 12.8 and mostly female (85.7%). Based on Shamblin scoring, 2 (4.8%) were classified as group I, 25 (59.5%) as group II, and 15 (35.7%) as group III. The amount of bleeding significantly increased with an increase in the Shamblin scores (P = 0.031; median: I: 45 cc; II: 250 cc, III: 400 cc). Also, there was a significant positive correlation between the size of the tumor and the estimated amount of bleeding (correlation coefficient = 0.660; P < 0.001), and also a significant reverse correlation with between bleeding and DTBOS (correlation coefficient = -0.345; P = 0.025). During the follow-up of the patients, 6 (14.3%) had abnormalities in their neurological evaluation. Receiver operating characteristic curve analysis revealed the size of tumor cutoff level 32.7 cm3 (3.2 cm radius) to be most predictive of postoperative neurological complication with an area under the curve = 0.83, sensitivity = 83.3%, specificity = 80.6%, a negative predictive value = 96.7%, and positive predictive value of 41.7%, and an accuracy of 81.0%. Furthermore, based on the predictive power of the models in our study, we demonstrated that a combination model including the tumor size, DTBOS, along with the Shamblin score had the most predictive power for neurological complications. CONCLUSIONS: By evaluating CBT size and DTBOS, paired with the use of the Shamblin classification, a better, more insightful understanding of possible risks and complications of CBT resection can be obtained, leading to deserved levels of patient care.

Is it necessary to define new diagnostic reference levels during pandemics like the Covid19-?

Introduction: This study intended to assess the dose length product (DLP), effective cumulative radiation dose (E.D.), and additional cancer risk (ACR) due to a chest CT scan to detect or follow up the Covid-19 disease in four university-affiliated hospitals that used different imaging protocols. Indeed, this study aimed to examine the differences in decision-making between different imaging centers in choosing chest CT imaging protocols during the pandemic, and to assess whether a new diagnostic reference level (DRL) is needed in pandemic situations. Methods: This retrospective study assessed the E.D. of all chest imagings for Covid-19 for six months in four different hospitals in our country. Imaging parameters and DLP (mGy.cm) were recorded. The E.D.s and ACRs from chest CT scans were calculated using an online calculator. Results: Thousand-six hundred patients were included in the study. The mean cumulative dose due to chest CT was 3.97 mSv which might cause 2.59 × 10-2 ACR. The mean cumulative E.D. in different hospitals was in the range of 1.96-9.51 mSv. Conclusions: The variety of mean E.D.s shows that different hospitals used different imaging protocols. Since there is no defined DRL in the pandemic, some centers use routine protocols, and others try to reduce the dose but insufficiently.In pandemics such as Covid-19, when CT scan is used for screening or follow-up, DLPs can be significantly lower than in normal situations. Therefore, international regularized organizations such as the international atomic energy agency (IAEA) or the international commission on radiological protection (IRCP) should provide new DRL ranges.

How can additional ultrasonography screening improve the detection of occult breast cancer in women with dense breasts?

PURPOSE: Although mammography is a gold standard for breast cancer screening, the number of cancers that cannot be detected with mammography is substantial, especially in dense-breast (DB) women. Breast sonography can be a useful and powerful screening tool in these cases. The aim of this study is to assess the application of whole-breast sonography in the evaluation of breast lesions in women with DB tissue and estimate its accuracy in comparison with mammography. MATERIAL AND METHODS: A total of 207 asymptomatic DB women participated in this study. The breast tissue density was assessed using ACR BI-RADS. Patients underwent high-resolution ultrasonography of the breast in addition to physical examination and mammography. Different risk factors were also assessed. RESULTS: 152 of 207 (73.4%) cases who had mammography performed had DB, and 55 (26.6%) cases had very dense breasts (very DBs). None of the cases had a positive history of malignancy, while 19% of them had a positive history of breast cancer in first- or second-degree relatives. CONCLUSIONS: All findings were higher in cases with DB compared to very DBs except for fibroadenoma, which was detected more in cases with very DBs. Our study showed that the prevalence of different breast lesions had a significant relationship with the density of the breast. In our study, 48.3% of the cases were diagnosed with a lesion in their sonography result, although 81.0% of them were benign lesions, and the other 19.0% needed follow-up or biopsy evaluation. A substantial number of mammographically occult breast lesions, either benign or malignant, could be detected by ultrasound in DB tissue.

An advanced multisystem histiocytic sarcoma in a pregnant woman: A case report.

Histiocytic sarcoma is an extremely rare disease that's hard to diagnose and treat, often leading to a poor prognosis. Here, we present a case report detailing a rare occurrence of HS in a 37-year-old pregnant woman who first presented with left shoulder pain, palpitations, and a productive cough at 20 weeks of gestation. Her diagnostic evaluations were performed, including different imaging modalities such as chest X-rays, CT scans, and MRI. Imaging revealed a large mediastinal mass with extensive involvement of the adrenal glands, lungs, and lymph nodes. The definitive diagnosis of HS is based on pathological and morphological features, and the immunohistochemistry report plays a key role. In our case, the diagnosis of HS was confirmed through pathological evaluation and immunohistochemistry, with a positive CD68 result obtained from a supraclavicular lymph node biopsy. A hospital committee comprising medical specialists like hematologists-oncologists, pathologists, pulmonologists, and obstetricians was brought together to assess the case collectively. The patient received chemotherapy, which alleviated her symptoms and maintained her condition. Based on the committee's recommendations, despite a healthy fetus and normal obstetric sonograms, the decision was made to terminate the pregnancy with the consent of the patient and her family. Despite initial improvement postchemotherapy, the patient's condition worsened, necessitating intubation. Tragically, two months after the initial admission, the patient passed away due to severe complications. In this case report, we provide a literature review and review of the patient's imaging reports. Since the patient is pregnant and HS is uncommon, it's important to highlight that this case is unique and worth sharing.

Determining the frequency of thyroid involvement in chest CT scans of COVID-19 patients and its correlation with the severity of lung involvement and survival of patients in 2020.

Introduction: This study aimed to determine the frequency of thyroid gland involvement in chest CT scans of patients with COVID-19 admitted to university-affiliated hospitals and assess its relationship with the severity of lung involvement and patient survival in 2020. Material and methods: In this retrospective cross-sectional study, 1000 PCR-positive patients with COVID-19 who were referred to University-affiliated Hospital in 2020 and had chest CT performed within 72 hours of admission to the hospital were examined. The data was collected by patient file information and CT findings recorded in the PACS system, including thyroid involvement, the severity of lung involvement, and findings related to the death and recovery of patients. Results: The mean age of the examined patients was 56 years. 525 people (52.5%) were men, and 475 (47.5%) were women. 14% had severe pulmonary involvement, and 9.3% had very severe involvement. Moreover, 15.9 percent of them had deceased. 19.7% had focal thyroid involvement, 14% had diffuse involvement, and 66.3% were healthy subjects. Male gender and older age showed a significant relationship with thyroid gland involvement. The severity of lung involvement, the death rate in patients, and hospitalization in ICU were also significantly related to thyroid gland involvement in patients with COVID. Discussion and conclusion: This study highlights the importance of considering thyroid-gland involvement in the comprehensive management of COVID-19 patients. Routine screening and monitoring of thyroid-function may facilitate earlier detection and appropriate management of thyroid-related complications, potentially improving clinical outcomes. This study suggests that in COVID-19 infection the monitoring of thyroid function is prudent, particularly in cases of more serious disease.

Cell Proliferation, Viability, Differentiation, and Apoptosis of Iron Oxide Labeled Stem Cells Transfected with Lipofectamine Assessed by MRI.

To assess in vitro and in vivo tracking of iron oxide labeled stem cells transfected by lipofectamine using magnetic resonance imaging (MRI), rat dental pulp stem cells (DPSCs) were characterized, labeled with iron oxide nanoparticles, and then transfected with lipofectamine to facilitate the internalization of these nanoparticles. Cell proliferation, viability, differentiation, and apoptosis were investigated. Prussian blue staining and MRI were used to trace transfected labeled cells. DPSCs were a morphologically spindle shape, adherent to culture plates, and positive for adipogenic and osteogenic inductions. They expressed CD73 and CD90 markers and lacked CD34 and CD45. Iron oxide labeling and transfection with lipofectamine in DPSCs had no toxic impact on viability, proliferation, and differentiation, and did not induce any apoptosis. In vitro and in vivo internalization of iron oxide nanoparticles within DPSCs were confirmed by Prussian blue staining and MRI tracking. Prussian blue staining and MRI tracking in the absence of any toxic effects on cell viability, proliferation, differentiation, and apoptosis were safe and accurate to track DPSCs labeled with iron oxide and transfected with lipofectamine. MRI can be a useful imaging modality when treatment outcome is targeted.

Polypectomy-induced encephalocele manifested as meningitis and CSF rhinorrhea in a pregnant woman: a case report.

Encephalocele is a protrusion of the intracranial contents through a cranium defect. Encephalocele is divided into primary (congenital) and secondary (acquired) classes. From an epidemiological point of view, primary encephalocele is much more prevalent than secondary cases. Furthermore, among the secondary causes of this condition, iatrogenic encephalocele is recognized as a rare phenomenon. In this case report, we introduce a case of secondary encephalocele in a 30-year-old pregnant female who came to our emergency center at 5 weeks of gestation with a vague headache in her forehead and a runny nose. she reported a history of nasal polypectomy 9 months ago and a 10-day hospitalization for meningitis 5 months prior to admission. MRI of the patient's brain showed evidence of cerebral parenchymal herniation to the right nasal cavity, which was suggestive of encephalocele. She was scheduled for endoscopic transnasal reconstruction, and during the operation, a significant right-sided posterior ethmoidal roof defect with CSF leak and encephalocele was revealed. Eventually, the skull defect was successfully repaired with a vascularized flap, and the patient was discharged in good general condition.

A notable improvement in spontaneous intracranial hypotension (SIH) after delivery in a pregnant woman: A case report.

Spontaneous intracranial hypotension (SIH) is a rare condition where the CSF pressure is lower than expected. In this report, we introduce a case of SIH in a 32-year-old pregnant woman who came to our emergency department at 32 weeks' gestation with a postural and bilateral headache. After MRI confirmation, conservative treatment was started for her, and a cesarean section was scheduled. After the operation, CT-myelography and CT-cisternography were performed for the patient to find the source of the CSF leak, which was located in the C3-C5 level. Still, due to the dangerous nature of the operation, the patient continued supportive treatment and had a significant improvement in his next MRI without any invasive procedure.

Evaluating the accuracy of simplified VCUG in comparison with traditional VCUG for diagnosis of urinary-reflux in children: Radiation dose reduction.

INTRODUCTION: Voiding cystourethrogram (VCUG) is an imaging technique for diagnosing urinary-reflux. VCUG requires X-ray exposure, increasing the risk of malignancies induced by ionizing radiation, especially in children. Considering the importance of early diagnosis of urinary-reflux using VCUG to prevent kidney complications and the significance of reducing the radiation dose during this imaging, this study intends to reduce the imaging views of VCUG and evaluate the urinary-reflux, using a reduced number of images. MATERIAL AND METHODS: Children referred to a University hospital who underwent VCUG participated in this study. The routine VCUG procedure contained five images. Two images of full-bladder and post-void of each patient were considered a simplified procedure and were evaluated by two radiologists to determine reflux and its grade. The sensitivity and specificity of simplified VCUG were determined. RESULTS: 182 patients with a mean age of 5.36±4.95 years old participated in this study. There were 90% and 82% agreement between routine and simplified VCUG results in the left and right kidneys. The simplified VCUG had 87.2% and 100% sensitivity and specificity in detecting the left-side reflux, 83 .9% and 100%, to detect the right-side reflux. CONCLUSION: The results showed that using two images instead of five can effectively diagnose and grade urinary-reflux. The simplified VCUG had a relatively good and acceptable agreement in comparison to the routine cystourethrogram. It can effectively reduce the patient's radiation dose, especially in patients who need to perform serial bladder imaging for follow-up after operation.

Incidental diagnosis of a rare endobronchial schwannoma in a 7-year-old girl: A case report.

Schwannomas are nerve sheath tumors that arise from Schwann cells and are mainly benign. The likelihood of endobronchial schwannoma amongst all intrapulmonary tumors is up to 0.2% and mainly presents late. This study described a pediatric endobronchial schwannomas case discovered incidentally during rigid bronchoscopy. This case is uncommon, and its report can help physicians diagnose the same cases. The case was a 7-year-old girl presenting with fever and cough who had no history of pulmonary disease or relevant family history. Physical examination, chest radiography, CT scan, and bronchoscopy were performed on the patient. A biopsy was taken from the observed mass obstructing the bronchus during bronchoscopy. The mass was resected. Pathology revealed low-grade spindle cell neoplasm and confirmed schwannoma in immunohistochemistry. Endobronchial schwannomas can happen in children presenting with simple symptoms. For benign lesions, the prognosis is generally good. Due to the slow growth of these tumors and the potential for recurrence after resection, long-term follow-up may be needed.

Correlation between contrast enhanced plaques and plaque diffusion restriction and their signal intensities in FLAIR images in patients who admitted with acute symptoms of multiple sclerosis.

INTRODUCTION: One of the most common demyelinating disorders is Multiple Sclerosis (MS), which can lead to extensive disability in patients. Appearance of active lesions can be an important sign of disease development. The correlation between the restriction of DWI signal, contrast-enhancement, and demyelinated plaque's signals were evaluated in this study. MATERIAL AND METHOD: 34 MS patients with 1043 MS-plaques who had acute attacks took part in this study. Three MRI pulse-sequences, FLAIR, DWI, and post-contrast enhanced T1 weighted, were compared. Using the signal intensity of MS-lesions and normal brain tissue in FLAIR images, lesion/noise ratio (LNR) and lesion/white-matter ratio (LWR) were calculated. Sensitivity and specificity of LNR and LWR were estimated to determine a cut off value. RESULTS: 7.86% of MS-plaques were enhanced in T1 contrast-enhanced MRI. 2.4% showed DWI restriction. 0.77% showed both diffusion-restriction and T1 contrast-enhancement, 1.63% indicated diffusion-restriction but no contrast-enhancement and 7.09% showed contrast-enhancement but no diffusion-restriction. Among diffusion-restricted plaques, 32% were enhanced in T1-weighted post-contrast enhanced images and it should be noted that diffusion-restriction was seen in 9.76% of enhanced plaques. The sensitivity and specificity of the DWI restriction and its effectiveness in detecting active-plaques were calculated as 12.31% and 98.26%, respectively. The accuracy of this method in detecting the active MS-plaques estimated as 92.91%. The cut-off value for LWR and LNR was between 0.9-1 and 24-28. CONCLUSION: By calculating LNR and LWR, the FLAIR images can be evaluated to detect new MS-plaques. LWR had higher sensitivity and specificity in comparison to LNR so it is a better index in the detection of active-plaques. Although post contrast T1 is the gold standard for evaluating active plaques, in the case of a contraindication to gadolinium, DWI can offer supplemental information on the diffusion restriction of MS plaques in a non-contrast protocol.

Magnetic resonance spectroscopy and its application in colorectal cancer diagnosis and screening: A narrative review.

There are several slightly invasive methods to detect colorectal carcinoma (CRC) including colonoscopy and sigmoidoscopy; but there is no noninvasive, accurate screening test. It is recommended to initiate screening at the age of 50 for non-familial CRC. Laboratory tests are routinely suggested if internal observation and imaging are recommended for further evaluation. Spectroscopic-based imaging, such as magnetic resonance spectroscopy (MRS) is an interesting and promising tool with the potential to be an alternative to some minimally invasive procedures, such as biopsy. Accordingly, MRS might be a suitable substitution for invasive methods, such as colonoscopy. This article aimed to review the studies that have evaluated the MRS technique as a screening tool in CRC.

Assessment of the Hallmarks of Wilson Disease in CT Scan Imaging.

INTRODUCTION: Owing to nonspecific clinical symptoms, Wilson disease (WD) diagnosis is often missed or delayed; hence, many patients reach end-stage liver disease. When cirrhosis takes place, it is difficult to distinguish between WD and other causes of cirrhosis by imaging alone. This study outlines abdominal computed tomography (CT) imaging findings that occur more frequently in patients with WD cirrhosis. MATERIAL AND METHODS: Fifty-seven patients with WD who had referred for liver transplantation took part in this study and underwent dynamic liver CT examination before transplantation. Qualitative and quantitative parameters including liver density, contour irregularity, dysmorphia, hypertrophy of caudate lobe, presence of focal parenchymal lesion, thickness of perihepatic fat layer, periportal thickness, lymphadenopathy, and other associated findings were recorded and evaluated. RESULTS: Among these patients, 85.9% had contour irregularity, 28% had hepatic dysmorphia, and periportal thickening and cholelithiasis were found in 25.5% and 12.3% of patients, respectively. Splenomegaly, lymphadenopathy, and portosystemic shunting were observed in all patients. Also, hyperdense nodules (>20 mm) and honeycomb pattern were detected in 65.2% and 15.2% of patients, respectively, in the arterial phase. In the portal phase, these findings were detected only in 13% and 4.3% of patients. Hypertrophy of caudate lobe was seen only in 12.2% of patients. CONCLUSION: WD-associated cirrhosis has many CT imaging findings, although most of them are nonspecific. Some findings, such as hyperdense nodules and honeycomb pattern in non-contrast-enhanced CT scan and arterial phase of triphasic CT scan with lack of hypertrophy of caudate lobes, are hallmarks of WD.

Fast Padé transform for increasing the signal to noise ratio of spectra provided by STEAM pulse sequence.

BACKGROUND/OBJECTIVE: There are two routine pulse-sequences for single voxel spectroscopy (SVS), point resolved spectroscopy (PRESS) and stimulated echo acquisition mode (STEAM). Although STEAM has several advantages in comparison to PRESS, signal/noise ratio (SNR) superiority of PRESS makes it the first choice for SVS. Application of fast Padé transform (FPT) instead of Fast Furrier transform (FFT) might increase the SNR of the signal produced by STEAM pulse-sequence and therefore allows the benefits of its advantages. We aimed to evaluate and compare the noise root mean square (RMS) and SNR provided by STEAM pulse-sequence using both FPT and FFT. MATERIALS AND METHOD: A gelatin-based phantom was constructed in a 19-cm acrylic cylinder. The phantom had two normal/tumoral parts. The SVS was performed using a 3T MRI scanner. STEAM pulse-sequence were used with the following parameters: TR = 2000 ms, TM = 10 ms, and three TEs of 20, 135 and 270 ms with two data-points of 1024 and 512 and voxel-size of 1 cm3. The raw data were extracted and processed using both FFT and FPT estimators to produce the spectrum. The noise RMS and SNR of Cho and Cr metabolites were assessed. RESULTS: According to the results, noise RMS of spectra provided by FPT were decreased between 3619.01-14252.94% in comparison to FFT (p< 0.00001). The SNR of Cr1 and Cho peaks of the spectra provided by FPT were increased more than 96.80 and 97.18, respectively (0.00006

A method for cranial target delineation in radiotherapy treatment planning aided by single-voxel magnetic resonance spectroscopy: evaluation using a custom-designed gel-based phantom and simulations.

OBJECTIVE: Magnetic resonance spectroscopy (MRS) has been useful in radiotherapy treatment planning (RTP) especially in tumor delineation. Routinely, 2D/3D MRSI data are used for this application. However, not all centers have access to 2D/3D MRSI. The objective of this study was to introduce a method of using single-voxel spectroscopy (SVS) data in target delineation and assess its reliability. METHODS: A gel-based phantom containing Creatine (Cr), N-acetyl-l-aspartic-acid (NAA), and Choline (Cho) was designed and built. The metabolite ratios simulate the normal and tumoral part of the brain. The jMRUI software (v. 6.0) was used to simulate a 1.5 T GE MRI scanner. The metabolite spectra provided by different time of echos (TE)s of the Point-RESolved Spectroscopy pulse-sequence (PRESS), different data-points, and post-processings were quantized by jMRUI. PseudoMRSI maps of Cho/Cr, NAA/Cr, and Cho + Cr/NAA were created. A conformity index (CI) was used to determine which metabolite-ratio isolines are more appropriate for tumor delineation. RESULTS: The simulation accuracy was verified. There were no differences > 4% between the measured and simulated spectra in peak regions. The pseudoMRSI map of Cho + Cr/NAA smoothly followed the complicated geometry of the tumor inside the gel-based phantom. The results showed that the single-voxel spectra produced by the PRESS pulse sequence with the TE of 144 ms, 512 data-points, and minimum post-processings of water suppression, eddy current correction, and baseline correction can be used for target delineation. CONCLUSION: This study suggests that SVS data can be used to aid target delineation by using a mathematical approach. This can enable a wider use of MR-derived information in radiotherapy. ADVANCES IN KNOWLEDGE: To the best of our knowledge, until now, 2D or 3D MRSI data provided from 3T MRI scanners have been used for MRS-based radiotherapy treatment planning. However, there are a lot of centers that are equipped to 1.5 T MRI scanners and some of them just equipped to SVS. This study introduces a mathematical approach to help these centers to take the benefits of MRS-based treatment planning.

MRI-Tracking of Dental Pulp Stem Cells In Vitro and In Vivo Using Dextran-Coated Superparamagnetic Iron Oxide Nanoparticles.

The aim of this study was to track dental pulp stem cells (DPSCs) labeled with dextran-coated superparamagnetic iron oxide nanoparticles (SPIONs) using magnetic resonance imaging (MRI). Dental pulp was isolated from male Sprague Dawley rats and cultured in Dulbecco's modified Eagle's medium F12 (DMEM-F12) and 10% fetal bovine serum. Effects of SPIONs on morphology, viability, apoptosis, stemness, and osteogenic and adipogenic differentiation of DPSCs were assessed. Prussian blue staining and MRI were conducted to determine in vitro efficiency of SPIONs uptake by the cells. Both non-labeled and labeled DPSCs were adherent to culture plates and showed spindle-shape morphologies, respectively. They were positive for osteogenic and adipogenic induction and expression of cluster of differentiation (CD) 73 and CD90 biomarkers, but negative for expression of CD34 and CD45 biomarkers. The SPIONs were non-toxic and did not induce apoptosis in doses less than 25 mg/mL. Internalization of the SPIONs within the DPSCs was confirmed by Prussian blue staining and MRI. Our findings revealed that the MRI-based method could successfully monitor DPSCs labeled with dextran-coated SPIONs without any significant effect on osteogenic and adipogenic differentiation, viability, and stemness of DPSCs. We provided the in vitro evidence supporting the feasibility of an MRI-based method to monitor DPSCs labeled with SPIONs without any significant reduction in viability, proliferation, and differentiation properties of labeled cells, showing that internalization of SPIONs within DPSCs were not toxic at doses less than 25 mg/mL. In general, the SPION labeling does not seem to impair cell survival or differentiation. SPIONs are biocompatible, easily available, and cost effective, opening a new avenue in stem cell labeling in regenerative medicine.

Voxel dosimetry: Comparison of MCNPX and DOSXYZnrc Monte Carlo codes in patient specific phantom calculations.

INTRODUCTION: Dose evaluation with two Monte Carlo codes using patient specific voxel phantom is presented in this paper. We employ both MCNPX and DOSXYZnrc to perform dosimetry for mathematical voxel phantoms generated by our in-house developed voxel phantom generator and EGSnrc/CTCreate respectively. MATERIAL AND METHOD: Our case study was a 2.5 × 2.4 × 2.4 cm3 tumor in the middle lobe of right lung of a male patient exposed to 6MV parallel beam. In order to compare these Monte Carlo codes with together gross tumor volume (GTV) and organ at risks (OAR) doses and dose volume histograms (DVH) were calculated. RESULTS: Comparing the mean absorbed dose results (in Gy) from both codes indicates that gross tumor volume, heart and spinal cord have 2% to 10% difference. The 10% difference between the codes were from the spinal cord region where was not in the therapy beam and it just received the scatter radiation. The dose volume DVH obtained from DOSXYZnrc results demonstrate a milder slope compared with MCNPX DVHs. CONCLUSION: It was revealed that MCNPX has some advantages in comparison to DOSXYZnrc, but it is important to consider that for equal precision in voxel dosimetry calculation, DOSXYZnrc runs faster than MCNPX and it is a great advantage.

Evaluation of the scattered radiations of lead and lead-free aprons in diagnostic radiology by MCNPX.

BACKGROUND: Over the past few years, because of high attenuation and lightweight, non-toxic, lead-free aprons (LFAs) have been replaced by lead aprons (LAs). Lots of studies declared that this fact was based on the interactions of diagnostic X-ray with material such as the photoelectric effect (PE) and Compton scattering. These studies have demonstrated that in these types of aprons, due to the presence of different K-edge absorption, PE has a wide absorption in various metals with divers K-edges. The measurement geometry in most of these studies was narrow beam geometry, i.e. a collimated source and a collimated detector with a large source-detector distance. OBJECTIVE: The present study intended to evaluate the attenuation of radiology scattered radiations in LAs and LFAs in both narrow and broad beam geometries, which is a more realistic situation, in order to check whether or not the higher attenuation is valid. METHODS: In this study, a lead apron contains (Pb + EPV) and two non-lead compounds of (W + Sn + EPVC) with different weight percent (Wt%) were evaluated in the energy range of diagnostic radiology (100 kVp). The MCNPX code was applied to simulate broad - and narrow-beam measurement geometries. The evaluations have been performed in three situations: 1st) the same density thickness of LA and LFAs 2nd) same line thickness of LA and LFAs 3rd) considering the thickness of LFAs which has the same attenuation with LAs i.e. lead equivalent thickness for LFAs in the narrow beam. Finally, the x-ray transmission ratio (I/I_0) of LAs and LFAs was compared in 100 kVp for three mentioned conditions. RESULTS: Our results indicated that LFAs had more radiation attenuation rather than LA in the 1st and 2nd conditions with both geometries. However, LFAs had lower attenuation in comparison to LAs in the 3rd condition with broad beam geometry. More importantly, the transmission ratio (I/I_0) of LFAs in the broad beam condition was more significant than LA. CONCLUSION: The scattered radiations produced by LFAs are more than LAs because of the production of characteristic radiations resulted from K-edge absorption in composited aprons. Consequently, the LFAs should be evaluated in both narrow and broad beam situation using the lead equivalent thickness of LFAs to make sure that the non-lead aprons do not increase the radiation dose of the user.

Assessment of the dose distribution of Minibeam radiotherapy for lung tumors in an anthropomorphic phantom: A feasibility study.

BACKGROUND: Microbeam radiotherapy (MRT) is a treatment in which radiation field is divided into several separate fields of 10-100 µm width and 100-400 µm spacing. In this treatment, normal tissue can tolerate high doses that are delivered to its small volumes. OBJECTIVE: MCNPX 2.4 Monte Carlo code was used to calculate the dose distribution of MRT in a lung tumor in a simulated Rando phantom. METHODS: The effects of tissue inhomogeneities, using contrast media and changing the number of beams were investigated. Dose volume histograms and beam profiles of target and organs at risk were assessed and the dose uniformity in the target region was evaluated using homogeneity. The conformity indices also used to quantify the conformation of the shape of prescribed isodose volume to the shape and size of the target. RESULTS: Tissue inhomogeneity of this region did not interfere significantly with target dose homogeneity. The use of contrast media or increasing the number of beams improved target dose homogeneity and decreased the dose to surrounding tissues. CONCLUSIONS: The results suggest that further investigation and evaluation of MRT for treatment of chest tumors is worthwhile.

Magnetic Resonance Spectroscopy and its Clinical Applications: A Review.

In vivo NMR spectroscopy is known as magnetic resonance spectroscopy (MRS). MRS has been applied as both a research and a clinical tool in order to detect visible or nonvisible abnormalities. The adaptability of MRS allows a technique that can probe a wide variety of metabolic uses across different tissues. Although MRS is mostly applied for brain tissue, it can be used for detection, localization, staging, tumour aggressiveness evaluation, and tumour response assessment of breast, prostate, hepatic, and other cancers. In this article, the medical applications of MRS in the brain, including tumours, neural and psychiatric disorder studies, breast, prostate, hepatic, gastrointestinal, and genitourinary investigations have been reviewed.