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Sample records for patient dose reduction

  1. Patient specific tube current modulation for CT dose reduction

    NASA Astrophysics Data System (ADS)

    Jin, Yannan; Yin, Zhye; Yao, Yangyang; Wang, Hui; Wu, Mingye; Kalra, Mannudeep; De Man, Bruno

    2015-03-01

    Radiation exposure during CT imaging has drawn growing concern from academia, industry as well as the general public. Sinusoidal tube current modulation has been available in most commercial products and used routinely in clinical practice. To further exploit the potential of tube current modulation, Sperl et al. proposed a Computer-Assisted Scan Protocol and Reconstruction (CASPAR) scheme [6] that modulates the tube current based on the clinical applications and patient specific information. The purpose of this study is to accelerate the CASPAR scheme to make it more practical for clinical use and investigate its dose benefit for different clinical applications. The Monte Carlo simulation in the original CASPAR scheme was substituted by the dose reconstruction to accelerate the optimization process. To demonstrate the dose benefit, we used the CATSIM package generate the projection data and perform standard FDK reconstruction. The NCAT phantom at thorax position was used in the simulation. We chose three clinical cases (routine chest scan, coronary CT angiography with and without breast avoidance) and compared the dose level with different mA modulation schemes (patient specific, sinusoidal and constant mA) with matched image quality. The simulation study of three clinical cases demonstrated that the patient specific mA modulation could significantly reduce the radiation dose compared to sinusoidal modulation. The dose benefits depend on the clinical application and object shape. With matched image quality, for chest scan the patient specific mA profile reduced the dose by about 15% compared to the sinusoid mA modulation; for the organ avoidance scan the dose reduction to the breast was over 50% compared to the constant mA baseline.

  2. Efficacy, Dose Reduction, and Resistance to High-dose Fluticasone in Patients with Eosinophilic Esophagitis

    PubMed Central

    Butz, Bridget K.; Wen, Ting; Gleich, Gerald J.; Furuta, Glenn T.; Spergel, Jonathan; King, Eileen; Kramer, Robert E.; Collins, Margaret H.; Stucke, Emily; Mangeot, Colleen; Jackson, W. Daniel; O’Gorman, Molly; Abonia, J. Pablo; Pentiuk, Scott; Putnam, Philip E.; Rothenberg, Marc E.

    2014-01-01

    Background & Aims We evaluated the efficacy and safety of high-dose swallowed fluticasone propionate (FP) and dose reduction in patients with eosinophilic esophagitis (EoE) and analyzed esophageal transcriptomes to identify mechanisms. Methods We conducted a randomized, multisite, double-blind, placebo-controlled trial of daily 1760 mcg FP in participants 3–30 years old with active EoE. Twenty-eight participants received FP and 14 received placebo. After 3 months, participants given FP who were in complete remission (CR) received 880 mcg FP daily, and participants in the FP or placebo groups who were not in CR continued or started, respectively, 1760 mcg FP daily for 3 additional months. The primary endpoint was histologic evidence for CR. Secondary endpoints were partial remission (PR), symptoms, compliance, esophageal gene expression, esophageal eosinophil count, and the relationship between clinical features and FP responsiveness. Results After 3 months, 65% of subjects given FP and no subjects given placebo were in CR (P=.0001); 12% of those given FP and 8% of those given placebo were in PR. In the FP group, 73% of subjects remained in CR and 20% were in PR after the daily dose was reduced by 50%. Extending FP therapy in FP-resistant participants did not induce remission. FP decreased heartburn severity (P=.041). Compliance, age, sex, atopic status, or anthropomorphic features were not associated with response to FP. Gene expression patterns in esophageal tissues of FP responders were similar to those of patients without EoE; there was evidence for heterogeneous steroid signaling in subjects that did not respond to FP. Conclusions Daily administration of a high dose of FP induces histologic remission in 65%–77% of patients with EoE after 3 months. A 50% dose reduction remained effective in 73%–93% of patients that initially responded to FP. Nonresponders had evidence of steroid resistance; histologic and molecular markers may predict resistance

  3. Patients with Fabry disease after enzyme replacement therapy dose reduction versus treatment switch.

    PubMed

    Weidemann, Frank; Krämer, Johannes; Duning, Thomas; Lenders, Malte; Canaan-Kühl, Sima; Krebs, Alice; Guerrero González, Hans; Sommer, Claudia; Üçeyler, Nurcan; Niemann, Markus; Störk, Stefan; Schelleckes, Michael; Reiermann, Stefanie; Stypmann, Jörg; Brand, Stefan-Martin; Wanner, Christoph; Brand, Eva

    2014-04-01

    Because of the shortage of agalsidase-beta in 2009, many patients with Fabry disease were treated with lower doses or were switched to agalsidase-alfa. This observational study assessed end-organ damage and clinical symptoms during dose reduction or switch to agalsidase-alfa. A total of 105 adult patients with Fabry disease who had received agalsidase-beta (1.0 mg/kg body weight) for ≥1 year were nonrandomly assigned to continue this treatment regimen (regular-dose group, n=38), receive a reduced dose of 0.3-0.5 mg/kg (dose-reduction group, n=29), or switch to 0.2 mg/kg agalsidase-alfa (switch group) and were followed prospectively for 1 year. We assessed clinical events (death, myocardial infarction, severe arrhythmia, stroke, progression to ESRD); changes in cardiac, renal, and neurologic function; and Fabry-related symptoms (neuropathic pain, hypohidrosis, diarrhea, and disease severity scores). Organ function and Fabry-related symptoms remained stable in the regular-dose group. In contrast, estimated GFR decreased by about 3 ml/min per 1.73 m(2) (P=0.01) in the dose-reduction group, and the median albumin-to-creatinine ratio increased from 114 (0-606) mg/g to 216 (0-2062) mg/g (P=0.03) in the switch group. Furthermore, mean Mainz Severity Score Index scores and frequencies of pain attacks, chronic pain, gastrointestinal pain, and diarrhea increased significantly in the dose-reduction and switch groups. In conclusion, patients receiving regular agalsidase-beta dose had a stable disease course, but dose reduction led to worsening of renal function and symptoms. Switching to agalsidase-alfa is safe, but microalbuminuria may progress and Fabry-related symptoms may deteriorate.

  4. Imatinib dose reduction in patients with chronic myeloid leukemia in sustained deep molecular response.

    PubMed

    Cervantes, Francisco; Correa, Juan-Gonzalo; Pérez, Isabel; García-Gutiérrez, Valentín; Redondo, Sara; Colomer, Dolors; Jiménez-Velasco, Antonio; Steegmann, Juan-Luis; Sánchez-Guijo, Fermín; Ferrer-Marín, Francisca; Pereira, Arturo; Osorio, Santiago

    2017-01-01

    To determine whether a lower imatinib dose could minimize toxicity while maintaining the molecular response (MR), imatinib dose was reduced to 300 mg daily in 43 patients with chronic myeloid leukemia (CML) in sustained deep molecular response to first-line imatinib 400 mg daily. At the time of dose reduction, median duration of the deep response was 4.1 (interquartile range (IQR) 2.2-5.9) years; molecular response was MR(4), MR(4.5), and MR(5) of the international scale in 6, 28, and 9 patients, respectively. Toxicity grade was 1, 2, and 3 in 28, 8, and 1 patients, respectively; 6 patients underwent dose reduction without having side effects. With a median of 1.6 (IQR 0.7-3.2) years on imatinib 300 mg daily, only one patient lost the deep molecular response to MR(3). At the last follow-up, response was MR(3), MR(4), MR(4.5), and MR(5) in 1, 3, 9, and 30 patients, respectively. Toxicity improvement was observed in 23 (62.2 %) of the 37 patients with side effects, decreasing to grade 0 in 20 of them. All but one anemic patients improved (p = 0.01), the median Hb increase in this subgroup of patients being 1 g/dL. In CML patients with sustained deep response to the standard imatinib dose, reducing to 300 mg daily significantly improves tolerability and preserves efficacy.

  5. Oral anticancer drugs: how limited dosing options and dose reductions may affect outcomes in comparative trials and efficacy in patients.

    PubMed

    Prasad, Vinay; Massey, Paul R; Fojo, Tito

    2014-05-20

    Historically, cancer medicine has avoided the problem of unequal dosing by comparing maximum-tolerated doses of intravenous regimens with proportionate dose reductions for toxicity. However, in recent years, with the development of numerous oral anticancer agents, dosing options are arbitrarily and increasingly limited by the size of pills. We contend that an underappreciated consequence of pill size is unequal dosing in comparative clinical trials and that this can have an impact on outcomes. We discuss how comparative effectiveness trials can be unbalanced and how the use of doses that are not sustainable might affect outcomes, especially marginal ones. We further argue that because of their poor tolerability and their limited dosing options, which often result in large dose adjustments in response to toxicity, the real-world clinical effectiveness of oral anticancer agents may be diminished and may not emulate results achieved in registration trials.

  6. Oral Anticancer Drugs: How Limited Dosing Options and Dose Reductions May Affect Outcomes in Comparative Trials and Efficacy in Patients

    PubMed Central

    Prasad, Vinay; Massey, Paul R.; Fojo, Tito

    2014-01-01

    Historically, cancer medicine has avoided the problem of unequal dosing by comparing maximum-tolerated doses of intravenous regimens with proportionate dose reductions for toxicity. However, in recent years, with the development of numerous oral anticancer agents, dosing options are arbitrarily and increasingly limited by the size of pills. We contend that an underappreciated consequence of pill size is unequal dosing in comparative clinical trials and that this can have an impact on outcomes. We discuss how comparative effectiveness trials can be unbalanced and how the use of doses that are not sustainable might affect outcomes, especially marginal ones. We further argue that because of their poor tolerability and their limited dosing options, which often result in large dose adjustments in response to toxicity, the real-world clinical effectiveness of oral anticancer agents may be diminished and may not emulate results achieved in registration trials. PMID:24711558

  7. Dose Reduction Techniques

    SciTech Connect

    WAGGONER, L.O.

    2000-05-16

    As radiation safety specialists, one of the things we are required to do is evaluate tools, equipment, materials and work practices and decide whether the use of these products or work practices will reduce radiation dose or risk to the environment. There is a tendency for many workers that work with radioactive material to accomplish radiological work the same way they have always done it rather than look for new technology or change their work practices. New technology is being developed all the time that can make radiological work easier and result in less radiation dose to the worker or reduce the possibility that contamination will be spread to the environment. As we discuss the various tools and techniques that reduce radiation dose, keep in mind that the radiological controls should be reasonable. We can not always get the dose to zero, so we must try to accomplish the work efficiently and cost-effectively. There are times we may have to accept there is only so much you can do. The goal is to do the smart things that protect the worker but do not hinder him while the task is being accomplished. In addition, we should not demand that large amounts of money be spent for equipment that has marginal value in order to save a few millirem. We have broken the handout into sections that should simplify the presentation. Time, distance, shielding, and source reduction are methods used to reduce dose and are covered in Part I on work execution. We then look at operational considerations, radiological design parameters, and discuss the characteristics of personnel who deal with ALARA. This handout should give you an overview of what it takes to have an effective dose reduction program.

  8. A method for patient dose reduction in dynamic contrast enhanced CT study

    SciTech Connect

    Mo Kim, Sun; Haider, Masoom A.; Milosevic, Michael; Jaffray, David A.; Yeung, Ivan W. T.

    2011-09-15

    Purpose: In dynamic contrast enhanced CT (DCE-CT) study, prolonged CT scanning with high temporal resolution is required to give accurate and precise estimates of kinetic parameters. However, such scanning protocol could lead to substantial radiation dose to the patient. A novel method is proposed to reduce radiation dose to patient, while maintaining high accuracy for kinetic parameter estimates in DCE-CT study. Methods: The method is based on a previous investigation that the arterial impulse response (AIR) in DCE-CT study can be predicted using a population-based scheme. In the proposed method, DCE-CT scanning is performed with relatively low temporal resolution, hence, giving rise to reduction in patient dose. A novel method is proposed to estimate the arterial input function (AIF) based on the coarsely sampled AIF. By using the estimated AIF in the tracer kinetic analysis of the coarsely sampled DCE-CT study, the calculated kinetic parameters are able to achieve a high degree of accuracy. The method was tested on a DCE-CT data set of 48 patients with cervical cancer scanned at high temporal resolution. A random cohort of 34 patients was chosen to construct the orthonormal bases of the AIRs via singular value decomposition method. The determined set of orthonormal bases was used to fit the AIFs in the second cohort (14 patients) at varying levels of down sampling. For each dataset in the second cohort, the estimated AIF was used for kinetic analyses of the modified Tofts and adiabatic tissue homogeneity models for each of the down-sampling schemes between intervals from 2 to 15 s. The results were compared with analyses done with the ''raw'' down-sampled AIF. Results: In the first group of 34 patients, there were 11 orthonormal bases identified to describe the AIRs. The AIFs in the second group were estimated in high accuracy based on the 11 orthonormal bases established in the first group along with down-sampled AIFs. Using the 11 orthonormal bases, the

  9. Yearly reduction of glucocorticoid dose by 50% as tapering schedule achieves complete remission for 124 pemphigus vulgaris patients.

    PubMed

    Wang, Mingyue; Gao, Yu; Peng, Yang; Zhao, Junyu; Chen, Xixue; Zhu, Xuejun

    2016-03-01

    Glucocorticoids are the first-line treatment for pemphigus vulgaris. Among 140 patients receiving systemic glucocorticoids, 124 patients achieved complete remission off or on a prednisone dose of ≤10 mg/day or less for 6 months or more. The mean average steroid controlling doses were 0.65, 0.62, 0.80, 1.08 and 1.38 mg/kg per day for the mucosal-dominant patients and the mild, moderate, severe and extensive cutaneous-involved patients, respectively (P < 0.001). The mean durations of the initial tapering after controlling doses started were 77.98, 48.78, 31.74 and 28.83 days when the disease was controlled with doses of 40 mg/day or less, 45-60 mg/day, 65-80 mg/day and more than 80 mg/day for the cutaneous-involved types, respectively (P < 0.005). Of the patients, 79.51% achieved complete remission within 3 years, 98.36% within 5 years and all within 6 years, which corresponded to a 50% yearly reduction of glucocorticoid dose. These successfully treated patients indicate that a severity-tailored initial dose of glucocorticoids, an initial tapering duration based on the initial dose and a subsequent 50% yearly tapering regimen may cure pemphigus vulgaris within 3-6 years.

  10. Patients with Fabry Disease after Enzyme Replacement Therapy Dose Reduction and Switch-2-Year Follow-Up.

    PubMed

    Lenders, Malte; Canaan-Kühl, Sima; Krämer, Johannes; Duning, Thomas; Reiermann, Stefanie; Sommer, Claudia; Stypmann, Jörg; Blaschke, Daniela; Üçeyler, Nurcan; Hense, Hans-Werner; Brand, Stefan-Martin; Wanner, Christoph; Weidemann, Frank; Brand, Eva

    2016-03-01

    Because of the shortage of agalsidase-β supply between 2009 and 2012, patients with Fabry disease either were treated with reduced doses or were switched to agalsidase-α. In this observational study, we assessed end organ damage and clinical symptoms with special focus on renal outcome after 2 years of dose-reduction and/or switch to agalsidase-α. A total of 89 adult patients with Fabry disease who had received agalsidase-β (1.0 mg/kg body wt) for >1 year were nonrandomly assigned to continue this treatment regimen (regular-dose group, n=24), to receive a reduced dose of 0.3-0.5 mg/kg and a subsequent switch to 0.2 mg/kg agalsidase-α (dose-reduction-switch group, n=28), or to directly switch to 0.2 mg/kg agalsidase-α (switch group, n=37) and were followed-up for 2 years. We assessed clinical events (death, myocardial infarction, severe arrhythmia, stroke, progression to ESRD), changes in cardiac and renal function, Fabry-related symptoms (pain, hypohidrosis, diarrhea), and disease severity scores. Determination of renal function by creatinine and cystatin C-based eGFR revealed decreasing eGFRs in the dose-reduction-switch group and the switch group. The Mainz Severity Score Index increased significantly in these two groups (P=0.02 and P<0.001, respectively), and higher frequencies of gastrointestinal pain occurred during follow-up. In conclusion, after 2 years of observation, all groups showed a stable clinical disease course with respect to serious clinical events. However, patients under agalsidase-β dose-reduction and switch or a direct switch to agalsidase-α showed a decline of renal function independent of the eGFR formula used.

  11. Prediction of Warfarin Dose Reductions in Puerto Rican Patients, Based on Combinatorial CYP2C9 and VKORC1 Genotypes

    PubMed Central

    Valentin, Isa Ivette; Vazquez, Joan; Rivera-Miranda, Giselle; Seip, Richard L; Velez, Meredith; Kocherla, Mohan; Bogaard, Kali; Cruz-Gonzalez, Iadelisse; Cadilla, Carmen L; Renta, Jessica Y; Felliu, Juan F; Ramos, Alga S; Alejandro-Cowan, Yirelia; Gorowski, Krystyna; Ruaño, Gualberto; Duconge, Jorge

    2012-01-01

    BACKGROUND The influence of CYP2C9 and VKORC1 polymorphisms on warfarin dose has been investigated in white, Asian, and African American populations but not in Puerto Rican Hispanic patients. OBJECTIVE To test the associations between genotypes, international normalized ratio (INR) measurements, and warfarin dosing and gauge the impact of these polymorphisms on warfarin dose, using a published algorithm. METHODS A retrospective warfarin pharmacogenetic association study in 106 Puerto Rican patients was performed. DNA samples from patients were assayed for 12 variants in both CYP2C9 and VKORC1 loci by HILOmet PhyzioType assay. Demographic and clinical nongenetic data were retrospectively collected from medical records. Allele and genotype frequencies were determined and Hardy-Weinberg equilibrium (HWE) was tested. RESULTS Sixty-nine percent of patients were carriers of at least one polymorphism in either the CYP2C9 or the VKORC1 gene. Double, triple, and quadruple carriers accounted for 22%, 5%, and 1%, respectively. No significant departure from HWE was found. Among patients with a given CYP2C9 genotype, warfarin dose requirements declined from GG to AA haplotypes; whereas, within each VKORC1 haplotype, the dose decreased as the number of CYP2C9 variants increased. The presence of these loss-of-function alleles was associated with more out-of-range INR measurements (OR = 1.38) but not with significant INR >4 during the initiation phase. Analyses based on a published pharmacogenetic algorithm predicted dose reductions of up to 4.9 mg/day in carriers and provided better dose prediction in an extreme subgroup of highly sensitive patients, but also suggested the need to improve predictability by developing a customized model for use in Puerto Rican patients. CONCLUSIONS This study laid important groundwork for supporting a prospective pharmacogenetic trial in Puerto Ricans to detect the benefits of incorporating relevant genomic information into a customized DNA

  12. Effect of rare earth filtration on patient exposure, dose reduction, and image quality in oral panoramic radiology

    SciTech Connect

    Tyndall, D.A.; Washburn, D.B.

    1987-01-01

    Rare earth intensifying screen material (Gd2O2S:Tb) was added to the standard Al filtration of an oral panoramic x-ray unit, resulting in a beam capable of achieving reductions in patient dose without a loss of image quality. The added rare earth filtration technique resulted in patient dose reductions of 21-56%, depending on anatomic sites, when compared to the conventional Al filtration technique. Films generated from both techniques were measured densitometrically and evaluated by a panel of practicing clinicians. Diagnostically significant differences were minimal. The results indicate that use of rare earth filters in oral panoramic radiography is an effective means of reducing exposures of dental patients to ionizing radiation.

  13. Rapid Automated Treatment Planning Process to Select Breast Cancer Patients for Active Breathing Control to Achieve Cardiac Dose Reduction

    SciTech Connect

    Wang Wei; Purdie, Thomas G.; Rahman, Mohammad; Marshall, Andrea; Liu Feifei; Fyles, Anthony

    2012-01-01

    Purpose: To evaluate a rapid automated treatment planning process for the selection of patients with left-sided breast cancer for a moderate deep inspiration breath-hold (mDIBH) technique using active breathing control (ABC); and to determine the dose reduction to the left anterior descending coronary artery (LAD) and the heart using mDIBH. Method and Materials: Treatment plans were generated using an automated method for patients undergoing left-sided breast radiotherapy (n = 53) with two-field tangential intensity-modulated radiotherapy. All patients with unfavorable cardiac anatomy, defined as having >10 cm{sup 3} of the heart receiving 50% of the prescribed dose (V{sub 50}) on the free-breathing automated treatment plan, underwent repeat scanning on a protocol using a mDIBH technique and ABC. The doses to the LAD and heart were compared between the free-breathing and mDIBH plans. Results: The automated planning process required approximately 9 min to generate a breast intensity-modulated radiotherapy plan. Using the dose-volume criteria, 20 of the 53 patients were selected for ABC. Significant differences were found between the free-breathing and mDIBH plans for the heart V{sub 50} (29.9 vs. 3.7 cm{sup 3}), mean heart dose (317 vs. 132 cGy), mean LAD dose (2,047 vs. 594 cGy), and maximal dose to 0.2 cm{sup 3} of the LAD (4,155 vs. 1,507 cGy, all p <.001). Of the 17 patients who had a breath-hold threshold of {>=}0.8 L, 14 achieved a {>=}90% reduction in the heart V{sub 50} using the mDIBH technique. The 3 patients who had had a breath-hold threshold <0.8 L achieved a lower, but still significant, reduction in the heart V{sub 50}. Conclusions: A rapid automated treatment planning process can be used to select patients who will benefit most from mDIBH. For selected patients with unfavorable cardiac anatomy, the mDIBH technique using ABC can significantly reduce the dose to the LAD and heart, potentially reducing the cardiac risks.

  14. Diuretics enhance effects of increased dose of candesartan on ambulatory blood pressure reduction in Japanese patients with uncontrolled hypertension treated with medium-dose angiotensin II receptor blockers.

    PubMed

    Sakima, Atsushi; Kita, Toshihiro; Nakada, Seigo; Yokota, Naoto; Tamaki, Noboru; Etoh, Takuma; Shimokubo, Toru; Kitamura, Kazuo; Takishita, Shuichi; Ohya, Yusuke

    2014-01-01

    Abstract Although blockade of the renin-angiotensin system by increasing the dose of angiotensin II receptor blockers (ARBs) is recommended to achieve clinical benefits in terms of blood pressure (BP) control and cardiovascular and renal outcomes, the effect of this increased dose on ambulatory BP monitoring has not been evaluated completely in Japanese patients with uncontrolled hypertension undergoing medium-dose ARB therapy. The primary objective of this study was to examine the effect of the relatively high dose of the ARB candesartan (12 mg/day) on 24-h systolic BP and the attainment of target BP levels in uncontrolled hypertension treated with a medium dose of ARBs. A total of 146 hypertensive patients (age: 69.9 ± 9.3 years; females: 65.8%) completed the study. After switching to candesartan at 12 mg/day, all these BP measurements decreased significantly (p<0.001). Attainment of the target office BP (p=0.0014) and 24-h BP levels (p=0.0296) also improved significantly. Subgroup analysis indicated that the reduction of 24-h systolic BP was larger in patients treated with diuretics than those without (p=0.0206). Multivariate analysis revealed a significant correlation between the combined ARB and diuretic therapy, and the change in 24-h systolic BP irrespective of preceding ARBs. In conclusion, the switching therapy to increased dose of candesartan caused significant reductions in office and ambulatory BP levels, and improved the attainment of target BP levels in patients with uncontrolled hypertension treated with a medium dose of ARBs. Combination with diuretics enhanced this effect.

  15. Feasibility of patient dose reduction based on various noise suppression filters for cone-beam computed tomography in an image-guided patient positioning system

    NASA Astrophysics Data System (ADS)

    Kamezawa, Hidemi; Arimura, Hidetaka; Shirieda, Katsutoshi; Kameda, Noboru; Ohki, Masafumi

    2016-05-01

    We investigated the feasibility of patient dose reduction based on six noise suppression filters for cone-beam computed tomography (CBCT) in an image-guided patient positioning (IGPP) system. A midpoint dose was employed as a patient dose index. First, a reference dose (RD) and low-dose (LD)-CBCT images were acquired with a reference dose and various low doses. Second, an automated rigid registration was performed for three axis translations to estimate patient setup errors between a planning CT image and the LD-CBCT images processed by six noise suppression filters (averaging filter, median filter, Gaussian filter, edge-preserving smoothing filter, bilateral filter, and adaptive partial median filter (AMF)). Third, residual errors representing the patient positioning accuracy were calculated as Euclidean distances between the setup error vectors estimated using the LD-CBCT and RD-CBCT images. Finally, the residual errors as a function of the patient dose index were estimated for LD-CBCT images processed by six noise suppression filters, and then the patient dose indices for the filtered LD-CBCT images were obtained at the same residual error as the RD-CBCT image. This approach was applied to an anthropomorphic phantom and four cancer patients. The patient dose for the LD-CBCT images was reduced to 19% of that for the RD-CBCT image for the phantom by using AMF, while keeping a same residual error of 0.47 mm as the RD-CBCT image by applying the noise suppression filters to the LD-CBCT images. The average patient dose was reduced to 31.1% for prostate cancer patients, and it was reduced to 82.5% for a lung cancer patient by applying the AMF. These preliminary results suggested that the proposed approach based on noise suppression filters could decrease the patient dose in IGPP systems.

  16. Feasibility of patient dose reduction based on various noise suppression filters for cone-beam computed tomography in an image-guided patient positioning system.

    PubMed

    Kamezawa, Hidemi; Arimura, Hidetaka; Shirieda, Katsutoshi; Kameda, Noboru; Ohki, Masafumi

    2016-05-07

    We investigated the feasibility of patient dose reduction based on six noise suppression filters for cone-beam computed tomography (CBCT) in an image-guided patient positioning (IGPP) system. A midpoint dose was employed as a patient dose index. First, a reference dose (RD) and low-dose (LD)-CBCT images were acquired with a reference dose and various low doses. Second, an automated rigid registration was performed for three axis translations to estimate patient setup errors between a planning CT image and the LD-CBCT images processed by six noise suppression filters (averaging filter, median filter, Gaussian filter, edge-preserving smoothing filter, bilateral filter, and adaptive partial median filter (AMF)). Third, residual errors representing the patient positioning accuracy were calculated as Euclidean distances between the setup error vectors estimated using the LD-CBCT and RD-CBCT images. Finally, the residual errors as a function of the patient dose index were estimated for LD-CBCT images processed by six noise suppression filters, and then the patient dose indices for the filtered LD-CBCT images were obtained at the same residual error as the RD-CBCT image. This approach was applied to an anthropomorphic phantom and four cancer patients. The patient dose for the LD-CBCT images was reduced to 19% of that for the RD-CBCT image for the phantom by using AMF, while keeping a same residual error of 0.47 mm as the RD-CBCT image by applying the noise suppression filters to the LD-CBCT images. The average patient dose was reduced to 31.1% for prostate cancer patients, and it was reduced to 82.5% for a lung cancer patient by applying the AMF. These preliminary results suggested that the proposed approach based on noise suppression filters could decrease the patient dose in IGPP systems.

  17. Reduction of Dose Delivered to Organs at Risk in Prostate Cancer Patients via Image-Guided Radiation Therapy

    SciTech Connect

    Pawlowski, Jason M.; Yang, Eddy S.; Malcolm, Arnold W.; Coffey, Charles W.; Ding, George X.

    2010-03-01

    Purpose: To determine whether image guidance can improve the dose delivered to target organs and organs at risk (OARs) for prostate cancer patients treated with intensity-modulated radiotherapy (IMRT). Methods and Materials: Eight prostate cancer patients were treated with IMRT to 76 Gy at 2 Gy per fraction. Daily target localization was performed via alignment of three intraprostatic fiducials and weekly kV-cone beam computed tomography (CBCT) scans. The prostate and OARs were manually contoured on each CBCT by a single physician. Daily patient setup shifts were obtained by comparing alignment of skin tattoos with the treatment position based on fiducials. Treatment fields were retrospectively applied to CBCT scans. The dose distributions were calculated using actual treatment plans (an 8-mm PTV margin everywhere except for 6-mm posteriorly) with and without image guidance shifts. Furthermore, the feasibility of margin reduction was evaluated by reducing planning margins to 4 mm everywhere except for 3 mm posteriorly. Results: For the eight treatment plans on the 56 CBCT scans, the average doses to 98% of the prostate (D98) were 102% (range, 99-104%) and 99% (range, 45-104%) with and without image guidance, respectively. Using margin reduction, the average D98s were 100% (range, 84-104%) and 92% (range, 40-104%) with and without image guidance, respectively. Conclusions: Currently, margins used in IMRT plans are adequate to deliver a dose to the prostate with conventional patient positioning using skin tattoos or bony anatomy. The use of image guidance may facilitate significant reduction of planning margins. Future studies to assess the efficacy of decreasing margins and improvement of treatment-related toxicities are warranted.

  18. Effects of a radiation dose reduction strategy for computed tomography in severely injured trauma patients in the emergency department: an observational study

    PubMed Central

    2011-01-01

    Background Severely injured trauma patients are exposed to clinically significant radiation doses from computed tomography (CT) imaging in the emergency department. Moreover, this radiation exposure is associated with an increased risk of cancer. The purpose of this study was to determine some effects of a radiation dose reduction strategy for CT in severely injured trauma patients in the emergency department. Methods We implemented the radiation dose reduction strategy in May 2009. A prospective observational study design was used to collect data from patients who met the inclusion criteria during this one year study (intervention group) from May 2009 to April 2010. The prospective data were compared with data collected retrospectively for one year prior to the implementation of the radiation dose reduction strategy (control group). By comparison of the cumulative effective dose and the number of CT examinations in the two groups, we evaluated effects of a radiation dose reduction strategy. All the patients met the institutional adult trauma team activation criteria. The radiation doses calculated by the CT scanner were converted to effective doses by multiplication by a conversion coefficient. Results A total of 118 patients were included in this study. Among them, 33 were admitted before May 2009 (control group), and 85 were admitted after May 2009 (intervention group). There were no significant differences between the two groups regarding baseline characteristics, such as injury severity and mortality. Additionally, there was no difference between the two groups in the mean number of total CT examinations per patient (4.8 vs. 4.5, respectively; p = 0.227). However, the mean effective dose of the total CT examinations per patient significantly decreased from 78.71 mSv to 29.50 mSv (p < 0.001). Conclusions The radiation dose reduction strategy for CT in severely injured trauma patients effectively decreased the cumulative effective dose of the total CT

  19. Reduction of eye lens radiation dose by orbital bismuth shielding in pediatric patients undergoing CT of the head: A Monte Carlo study

    SciTech Connect

    Perisinakis, Kostas; Raissaki, Maria; Tzedakis, Antonis; Theocharopoulos, Nicholas; Damilakis, John; Gourtsoyiannis, Nicholas

    2005-04-01

    Our aim in the study was to assess the eye lens dose reduction resulting from the use of radioprotective bismuth garments to shield the eyes of pediatric patients undergoing head CT. The Monte Carlo N-particle transport code and mathematical humanoid phantoms representing the average individual at different ages were used to determine eye lens dose reduction accomplished with bismuth shielding of the eye in the following simulated CT scans: (a) scanning of the orbits, (b) scanning of the whole head, and (c) 20 deg. angled scanning of the brain excluding the orbits. The effect of bismuth shielding on the eye lens dose was also investigated using an anthropomorphic phantom and thermoluminescence dosimetry (TLD). Eye lens dose reduction achieved by bismuth shielding was measured in 16 patients undergoing multiphase CT scanning of the head. The patient's scans were divided in the following: CT examinations where the eye globes were entirely included (n=5), partly included (n=6) and excluded (n=5) from the scanned region. The eye lens dose reduction depended mainly on the scan boundaries set by an operator. The average eye lens dose reduction determined by Monte Carlo simulation was 38.2%, 33.0% and <1% for CT scans of the orbits, whole head, and brain with an angled gantry, respectively. The difference between the Monte Carlo derived eye lens dose reduction factor values and corresponding values determined directly by using the anthropomorphic phantom head was found less than 5%. The mean eye lens dose reduction achieved by bismuth shielding in pediatric patients were 34%, 20% and <2% when eye globes were entirely included, partly included and excluded from the scanned region, respectively. A significant reduction in eye lens dose may be achieved by using superficial orbital bismuth shielding during pediatric head CT scans. However, bismuth garments should not be used in children when the eyes are excluded from the primarily exposed region.

  20. Impact of dose reductions on efficacy outcome in heart transplant patients receiving enteric-coated mycophenolate sodium or mycophenolate mofetil at 12 months post-transplantation.

    PubMed

    Segovia, Javier; Gerosa, Gino; Almenar, Luis; Livi, Ugolino; Viganò, Mario; Arizón, Jose Maria; Yonan, Nizar; Di Salvo, Thomas G; Renlund, Dale G; Kobashigawa, Jon A

    2008-01-01

    Mycophenolic acid (MPA) dose reduction is associated with increased risk of rejection and graft loss in renal transplantation. This analysis investigated the impact of MPA dose changes with enteric-coated mycophenolate sodium (EC-MPS) or mycophenolate mofetil (MMF) in de novo heart transplant recipients. In a 12-month, single-blind trial, 154 patients (EC-MPS, 78; MMF, 76) were randomized to either EC-MPS (1080 mg bid) or MMF (1500 mg bid) in combination with cyclosporine and steroids. The primary efficacy variable was the incidence of treatment failure, comprising a composite of biopsy-proven (BPAR) and treated acute rejection, graft loss or death. Significantly fewer patients receiving EC-MPS required > or =2 dose reductions than patients on MMF (26.9% vs. 42.1% of patients, p = 0.048). Accordingly, the average daily dose of EC-MPS as a percentage of the recommended dose was significantly higher than for MMF (88.4% vs. 79.0%, p = 0.016). Among patients requiring > or =1 dose reduction, the incidence of treated BPAR grade > or =3A was significantly lower with EC-MPS compared with MMF (23.4% vs. 44.0%, p = 0.032). These data suggest that EC-MPS-treated heart transplant patients are less likely to require multiple dose reductions than those on MMF which may be associated with a significantly lower risk of treated BPAR > or =3A.

  1. Simulation of dose reduction in tomosynthesis

    SciTech Connect

    Svalkvist, Angelica; Baath, Magnus

    2010-01-15

    Purpose: Methods for simulating dose reduction are valuable tools in the work of optimizing radiographic examinations. Using such methods, clinical images can be simulated to have been collected at other, lower, dose levels without the need of additional patient exposure. A recent technology introduced to healthcare that needs optimization is tomosynthesis, where a number of low-dose projection images collected at different angles is used to reconstruct section images of an imaged object. The aim of the present work was to develop a method of simulating dose reduction for digital radiographic systems, suitable for tomosynthesis. Methods: The developed method uses information about the noise power spectrum (NPS) at the original dose level and the simulated dose level to create a noise image that is added to the original image to produce an image that has the same noise properties as an image actually collected at the simulated dose level. As the detective quantum efficiency (DQE) of digital detectors operating at the low dose levels used for tomosynthesis may show a strong dependency on the dose level, it is important that a method for simulating dose reduction for tomosynthesis takes this dependency into account. By applying an experimentally determined relationship between pixel mean and pixel variance, variations in both dose and DQE in relevant dose ranges are taken into account. Results: The developed method was tested on a chest tomosynthesis system and was shown to produce NPS of simulated dose-reduced projection images that agreed well with the NPS of images actually collected at the simulated dose level. The simulated dose reduction method was also applied to tomosynthesis examinations of an anthropomorphic chest phantom, and the obtained noise in the reconstructed section images was very similar to that of an examination actually performed at the simulated dose level. Conclusions: In conclusion, the present article describes a method for simulating dose

  2. Assessment of patient dose reduction by bismuth shielding in CT using measurements, GEANT4 and MCNPX simulations.

    PubMed

    Mendes, M; Costa, F; Figueira, C; Madeira, P; Teles, P; Vaz, P

    2015-07-01

    This work reports on the use of two different Monte Carlo codes (GEANT4 and MCNPX) for assessing the dose reduction using bismuth shields in computer tomography (CT) procedures in order to protect radiosensitive organs such as eye lens, thyroid and breast. Measurements were performed using head and body PMMA phantoms and an ionisation chamber placed in five different positions of the phantom. Simulations were performed to estimate Computed Tomography Dose Index values using GEANT4 and MCNPX. The relative differences between measurements and simulations were <10 %. The dose reduction arising from the use of bismuth shielding ranges from 2 to 45 %, depending on the position of the bismuth shield. The percentage of dose reduction was more significant for the area covered by the bismuth shielding (36 % for eye lens, 39 % for thyroid and 45 % for breast shields).

  3. Radiation dose reduction for patients with extranodal NK/T-cell lymphoma with complete response after initial induction chemotherapy

    PubMed Central

    Wang, Liang; Bi, Xi-wen; Xia, Zhong-jun; Huang, Hui-qiang; Jiang, Wen-qi; Zhang, Yu-jing

    2016-01-01

    Previous studies have found that radiotherapy (RT) dose less than 50 Gy resulted in inferior outcomes for early stage extranodal NK/T-cell lymphoma (ENKTL). Nowadays, induction chemotherapy (CT) followed by RT consolidation is often used. For patients who get complete response (CR) after CT, whether RT dose can be safely reduced or not remains unknown. This retrospective study compared the survival outcomes between patients who received higher dose (>50 Gy) and lower dose (≤50 Gy) RT after CR was attained by CT. One hundred and forty four patients of early stage ENKTL got CR after induction CT and received RT consolidation. Thirty-one patients received lower dose RT (median 46 Gy, range, 36–50 Gy), and 113 patients received higher dose RT (median 56 Gy, range, 52–66 Gy). In univariate survival analysis, age >60, local tumor invasion, and non-asparaginase-based CT were associated with inferior progression-free survival (PFS) and overall survival (OS). However, there were no differences in PFS and OS between patients treated with higher and lower dose RT, which was confirmed in the multivariate survival analysis. Furthermore, reduced dose RT did not affect local control rate. Most common RT-related side effects were grade 1/2 mucositis and dermatitis, and the incidence rate of grade 3 mucositis or dermatitis was lower in patients treated with reduced dose RT (9.7% vs 15.0% for mucositis, and 6.5% vs 17.7% for dermatitis). In conclusion, this study found that RT dose could be safely reduced without compromising survival outcomes and further improved RT-related side effects. Prospective randomized controlled trials are warranted to validate our findings. PMID:27713641

  4. Multicentric survey on dose reduction/interruption of cancer drug therapy in 12.472 patients: indicators of suspected adverse reactions.

    PubMed

    Casadei Gardini, Andrea; Tenti, Elena; Masini, Carla; Nanni, Oriana; Scarpi, Emanuela; Valgiusti, Martina; Restuccia, Silvia; Gallani, Maria Laura; Palazzini, Simonetta; Bianchini, Erica; Menozzi, Silvia; Maugeri, Antonio; Amadori, Dino; Minguzzi, Martina; Frassineti, Giovanni Luca

    2016-06-28

    Antiblastic drugs have a high number of potential side-effects. Paradoxically, according to the National Network of Pharmacovigilance, the number of reported adverse reactions to these agents is proportionally lower than that registered for non antiblastic drugs. Critical phenomena such as treatment interruptions and significant dose reductions within the first two months of use may be indicators of adverse drug reactions. The aim of the present study was to increase our knowledge of pharmacovigilance to facilitate the actions taken to improve the risk-benefit profile of cancer drugs and, consequently, their safety. This retrospective observational survey was carried out on prescriptions from 1st January 2012 to 31st December 2012.Dose reductions of more than 10% during the first 90 days of therapy were considered as a surrogate indicator of an adverse reaction. Dose interruptions during the first 60 days of therapy were taken into consideration. Of the12,472 patients 1,248 underwent a dose reduction. The drugs that most often required a dose reduction were paclitaxel and oxaliplatin (17.4% and 17.3%, respectively), docetaxel (14.8%), carboplatin (15%), fluorouracil (10.7%) and, among oral medications, capecitabine (6.9%). Of the 1896 patients treated with the same drugs, 9.7% interrupted treatment. Patients required a lower dose reduction than that reported by other authors. Around 15% of cases underwent a 30% dose reduction within three months of starting therapy, indicating a possible adverse reaction. Constant monitoring of dose prescription and continuous training of medical and nursing staff are clearly needed to increase awareness of the importance of reporting adverse events.

  5. A double-blind randomized clinical trial of different doses of transdermal nicotine patch for smoking reduction and cessation in long-term hospitalized schizophrenic patients.

    PubMed

    Chen, Hsing-Kang; Lan, Tsuo-Hung; Wu, Bo-Jian

    2013-02-01

    There have been many studies of smoking cessation using nicotine replacement therapy (NRT) with schizophrenic patients, but none exploring the smoking-reduction effects of varying doses of NRT in long-stay patients with schizophrenia. This study aimed to examine the effect of different doses of the nicotine transdermal patch on smoking-reduction and cessation outcomes in long-term hospitalized schizophrenic patients. A total of 184 subjects participated in a randomized, controlled, double-blind 8-week clinical trial. Participants were randomized into two groups using two different doses of NRT: a high-dose NRT group (31.2 mg for the first 4 weeks, then 20.8 mg for 4 weeks, n = 92) or a low-dose NRT group (20.8 mg for 8 weeks, n = 92). The 7-day point prevalence of abstinence was 2.7 % (5/184). Participants in the low-dose NRT group reduced smoking by 3.1 more cigarettes on average than those in the high-dose group (p = 0.005). However, a repeated measures analysis of variance revealed that the main effect of changes in the number of cigarettes smoked, comparing the two types of treatment across periods, was not significant (p = 0.35, partial eta square = 0.018). In summary, among a cohort of chronic institutionalized schizophrenic patients, smoking cessation and reduction outcomes were not correlated with NRT dose, and the cessation rate was much lower than rates in similar studies. It indicates that long-term hospitalized schizophrenic patients have more difficulties with quitting smoking. More effective integrative smoking cessation programs should be addressed for these patients.

  6. Examining Margin Reduction and Its Impact on Dose Distribution for Prostate Cancer Patients Undergoing Daily Cone-Beam Computed Tomography

    SciTech Connect

    Hammoud, Rabih Patel, Samir H.; Pradhan, Deepak; Kim, Jinkoo; Guan, Harrison; Li Shidong; Movsas, Benjamin

    2008-05-01

    Purpose: To examine the dosimetric impact of margin reduction and quantify residual error after three-dimensional (3D) image registration using daily cone-beam computed tomography (CBCT) for prostate cancer patients. Methods and Materials: One hundred forty CBCTs from 5 prostate cancer patients were examined. Two intensity-modulated radiotherapy plans were generated on CT simulation on the basis of two planning target volume (PTV) margins: 10 mm all around the prostate and seminal vesicles except 6 mm posteriorly (10/6) and 5 mm all around except 3 mm posteriorly (5/3). Daily CBCT using the Varian On-Board Imaging System was acquired. The 10/6 and 5/3 simulation plans were overlaid onto each CBCT, and each CBCT plan was calculated. To examine residual error, PlanCT/CBCT intensity-based 3D image registration was performed for prostate localization using center of mass and maximal border displacement. Results: Prostate coverage was within 2% between the 10/6 and 5/3 plans. Seminal vesicle coverage was reduced with the 5/3 plan compared with the 10/6 plan, with coverage difference within 7%. The 5/3 plan allowed 30-50% sparing of bladder and rectal high-dose regions. For residual error quantification, center of mass data show that 99%, 93%, and 96% of observations fall within 3 mm in the left-right, anterior-posterior, and superior-inferior directions, respectively. Maximal border displacement observations range from 79% to 99%, within 5 mm for all directions. Conclusion: Cone-beam CT dosimetrically validated a 10/6 margin when soft-tissue localization is not used. Intensity-based 3D image registration has the potential to improve target localization and to provide guidelines for margin definition.

  7. Exhaling a budesonide inhaler through the nose results in a significant reduction in dose requirement of budesonide nasal spray in patients having asthma with rhinitis.

    PubMed

    Shaikh, W A

    1999-01-01

    Budesonide, an inhaled corticosteroid is used routinely in the treatment of bronchial asthma and rhinitis. Although inhaled corticosteroids in therapeutic doses are unlikely to result in systemic side effects, there is as yet skepticism about their routine and prolonged use. The aim of this study was to determine whether budesonide inhalation through a metered dose inhaler, when exhaled through the nose could result in a reduction in the dose requirement of budesonide metered nasal spray in patients having perennial allergic asthma with rhinitis. This study was an open, parallel, comparative, crossover trial in which 49 young patients having perennial allergic asthma with rhinitis were divided into two groups and administered either a combination of budesonide metered dose inhaler with a budesonide nasal spray or a budesonide inhaler alone, which was to be exhaled through the nose. Both groups were later crossed over and weekly symptom scores and peak nasal inspiratory flow rates were monitored during each phase of the study. Finally, patients who volunteered from both groups were instructed to note the reduction in dose requirement of budesonide nasal spray while using a budesonide inhaler and exhaling it through the nose. The results of this study reveal that when a budesonide inhaler is exhaled through the nose, it results in an improvement in symptom scores and peak nasal inspiratory flow rates, which were significantly less than those obtained in the group using both a budesonide nasal spray and a metered dose inhaler. In addition, exhaling budesonide through the nose results in a 40.1% reduction in the dose requirement of a budesonide nasal spray, which is statistically significant (p < 0.001).

  8. Radiation-Induced Noncancer Risks in Interventional Cardiology: Optimisation of Procedures and Staff and Patient Dose Reduction

    PubMed Central

    Khairuddin Md Yusof, Ahmad

    2013-01-01

    Concerns about ionizing radiation during interventional cardiology have been increased in recent years as a result of rapid growth in interventional procedure volumes and the high radiation doses associated with some procedures. Noncancer radiation risks to cardiologists and medical staff in terms of radiation-induced cataracts and skin injuries for patients appear clear potential consequences of interventional cardiology procedures, while radiation-induced potential risk of developing cardiovascular effects remains less clear. This paper provides an overview of the evidence-based reviews of concerns about noncancer risks of radiation exposure in interventional cardiology. Strategies commonly undertaken to reduce radiation doses to both medical staff and patients during interventional cardiology procedures are discussed; optimisation of interventional cardiology procedures is highlighted. PMID:24027768

  9. SU-E-J-183: Quantifying the Image Quality and Dose Reduction of Respiratory Triggered 4D Cone-Beam Computed Tomography with Patient- Measured Breathing

    SciTech Connect

    Cooper, B; OBrien, R; Kipritidis, J; Keall, P

    2014-06-01

    Purpose: Respiratory triggered four dimensional cone-beam computed tomography (RT 4D CBCT) is a novel technique that uses a patient's respiratory signal to drive the image acquisition with the goal of imaging dose reduction without degrading image quality. This work investigates image quality and dose using patient-measured respiratory signals for RT 4D CBCT simulations instead of synthetic sinusoidal signals used in previous work. Methods: Studies were performed that simulate a 4D CBCT image acquisition using both the novel RT 4D CBCT technique and a conventional 4D CBCT technique from a database of oversampled Rando phantom CBCT projections. A database containing 111 free breathing lung cancer patient respiratory signal files was used to create 111 RT 4D CBCT and 111 conventional 4D CBCT image datasets from realistic simulations of a 4D RT CBCT system. Each of these image datasets were compared to a ground truth dataset from which a root mean square error (RMSE) metric was calculated to quantify the degradation of image quality. The number of projections used in each simulation is counted and was assumed as a surrogate for imaging dose. Results: Based on 111 breathing traces, when comparing RT 4D CBCT with conventional 4D CBCT the average image quality was reduced by 7.6%. However, the average imaging dose reduction was 53% based on needing fewer projections (617 on average) than conventional 4D CBCT (1320 projections). Conclusion: The simulation studies using a wide range of patient breathing traces have demonstrated that the RT 4D CBCT method can potentially offer a substantial saving of imaging dose of 53% on average compared to conventional 4D CBCT in simulation studies with a minimal impact on image quality. A patent application (PCT/US2012/048693) has been filed which is related to this work.

  10. Severe Hyperbilirubinemia in an HIV-HCV-Coinfected Patient Starting the 3D Regimen That Resolved After TDM-Guided Atazanavir Dose Reduction.

    PubMed

    Cattaneo, Dario; Riva, Agostino; Clementi, Emilio; Milazzo, Laura; Gervasoni, Cristina

    2016-06-01

    The combination of ombitasvir, dasabuvir, and paritaprevir/ritonavir (considered as the 3D regimen) has proven to be associated with high sustained virologic response and optimal tolerability in hepatitis C virus-infected patients. Here, we describe an HIV-HCV-coinfected patient who experienced a grade 4 hyperbilirubinemia and a 2.5-fold increase in the atazanavir plasma trough concentrations few days after the start of 3D-based antiviral therapy who benefited from an atazanavir dose reduction guided by therapeutic drug monitoring.

  11. Quantifying the image quality and dose reduction of respiratory triggered 4D cone-beam computed tomography with patient-measured breathing

    NASA Astrophysics Data System (ADS)

    Cooper, Benjamin J.; O'Brien, Ricky T.; Kipritidis, John; Shieh, Chun-Chien; Keall, Paul J.

    2015-12-01

    Respiratory triggered four dimensional cone-beam computed tomography (RT 4D CBCT) is a novel technique that uses a patient’s respiratory signal to drive the image acquisition with the goal of imaging dose reduction without degrading image quality. This work investigates image quality and dose using patient-measured respiratory signals for RT 4D CBCT simulations. Studies were performed that simulate a 4D CBCT image acquisition using both the novel RT 4D CBCT technique and a conventional 4D CBCT technique. A set containing 111 free breathing lung cancer patient respiratory signal files was used to create 111 pairs of RT 4D CBCT and conventional 4D CBCT image sets from realistic simulations of a 4D CBCT system using a Rando phantom and the digital phantom, XCAT. Each of these image sets were compared to a ground truth dataset from which a mean absolute pixel difference (MAPD) metric was calculated to quantify the degradation of image quality. The number of projections used in each simulation was counted and was assumed as a surrogate for imaging dose. Based on 111 breathing traces, when comparing RT 4D CBCT with conventional 4D CBCT, the average image quality was reduced by 7.6% (Rando study) and 11.1% (XCAT study). However, the average imaging dose reduction was 53% based on needing fewer projections (617 on average) than conventional 4D CBCT (1320 projections). The simulation studies have demonstrated that the RT 4D CBCT method can potentially offer a 53% saving in imaging dose on average compared to conventional 4D CBCT in simulation studies using a wide range of patient-measured breathing traces with a minimal impact on image quality.

  12. Dose reduction at nuclear power plants

    SciTech Connect

    Baum, J.W.; Dionne, B.J.

    1983-01-01

    The collective dose equivalent at nuclear power plants increased from 1250 rem in 1969 to nearly 54,000 rem in 1980. This rise is attributable primarily to an increase in nuclear generated power from 1289 MW-y to 29,155 MW-y; and secondly, to increased average plant age. However, considerable variation in exposure occurs from plant to plant depending on plant type, refueling, maintenance, etc. In order to understand the factors influencing these differences, an investigation was initiated to study dose-reduction techniques and effectiveness of as low as reasonably achievable (ALARA) planning at light water plants. Objectives are to: identify high-dose maintenance tasks and related dose-reduction techniques; investigate utilization of high-reliability, low-maintenance equipment; recommend improved radioactive waste handling equipment and procedures; examine incentives for dose reduction; and compile an ALARA handbook.

  13. A Combination of Spatial and Recursive Temporal Filtering for Noise Reduction when Using Region of Interest (ROI) Fluoroscopy for Patient Dose Reduction in Image Guided Vascular Interventions with Significant Anatomical Motion

    PubMed Central

    Nagesh, S.V. Setlur; Khobragade, P.; Ionita, C.; Bednarek, D.R; Rudin, S.

    2015-01-01

    Because x-ray based image-guided vascular interventions are minimally invasive they are currently the most preferred method of treating disorders such as stroke, arterial stenosis, and aneurysms; however, the x-ray exposure to the patient during long image-guided interventional procedures could cause harmful effects such as cancer in the long run and even tissue damage in the short term. ROI fluoroscopy reduces patient dose by differentially attenuating the incident x-rays outside the region-of-interest. To reduce the noise in the dose-reduced regions previously recursive temporal filtering was successfully demonstrated for neurovascular interventions. However, in cardiac interventions, anatomical motion is significant and excessive recursive filtering could cause blur. In this work the effects of three noise-reduction schemes, including recursive temporal filtering, spatial mean filtering, and a combination of spatial and recursive temporal filtering, were investigated in a simulated ROI dose-reduced cardiac intervention. First a model to simulate the aortic arch and its movement was built. A coronary stent was used to simulate a bio-prosthetic valve used in TAVR procedures and was deployed under dose-reduced ROI fluoroscopy during the simulated heart motion. The images were then retrospectively processed for noise reduction in the periphery, using recursive temporal filtering, spatial filtering and a combination of both. Quantitative metrics for all three noise reduction schemes are calculated and are presented as results. From these it can be concluded that with significant anatomical motion, a combination of spatial and recursive temporal filtering scheme is best suited for reducing the excess quantum noise in the periphery. This new noise-reduction technique in combination with ROI fluoroscopy has the potential for substantial patient-dose savings in cardiac interventions. PMID:26900203

  14. A Combination of Spatial and Recursive Temporal Filtering for Noise Reduction when Using Region of Interest (ROI) Fluoroscopy for Patient Dose Reduction in Image Guided Vascular Interventions with Significant Anatomical Motion.

    PubMed

    Nagesh, S V Setlur; Khobragade, P; Ionita, C; Bednarek, D R; Rudin, S

    2015-02-21

    Because x-ray based image-guided vascular interventions are minimally invasive they are currently the most preferred method of treating disorders such as stroke, arterial stenosis, and aneurysms; however, the x-ray exposure to the patient during long image-guided interventional procedures could cause harmful effects such as cancer in the long run and even tissue damage in the short term. ROI fluoroscopy reduces patient dose by differentially attenuating the incident x-rays outside the region-of-interest. To reduce the noise in the dose-reduced regions previously recursive temporal filtering was successfully demonstrated for neurovascular interventions. However, in cardiac interventions, anatomical motion is significant and excessive recursive filtering could cause blur. In this work the effects of three noise-reduction schemes, including recursive temporal filtering, spatial mean filtering, and a combination of spatial and recursive temporal filtering, were investigated in a simulated ROI dose-reduced cardiac intervention. First a model to simulate the aortic arch and its movement was built. A coronary stent was used to simulate a bio-prosthetic valve used in TAVR procedures and was deployed under dose-reduced ROI fluoroscopy during the simulated heart motion. The images were then retrospectively processed for noise reduction in the periphery, using recursive temporal filtering, spatial filtering and a combination of both. Quantitative metrics for all three noise reduction schemes are calculated and are presented as results. From these it can be concluded that with significant anatomical motion, a combination of spatial and recursive temporal filtering scheme is best suited for reducing the excess quantum noise in the periphery. This new noise-reduction technique in combination with ROI fluoroscopy has the potential for substantial patient-dose savings in cardiac interventions.

  15. A combination of spatial and recursive temporal filtering for noise reduction when using region of interest (ROI) fluoroscopy for patient dose reduction in image guided vascular interventions with significant anatomical motion

    NASA Astrophysics Data System (ADS)

    Setlur Nagesh, S. V.; Khobragade, P.; Ionita, C.; Bednarek, D. R.; Rudin, S.

    2015-03-01

    Because x-ray based image-guided vascular interventions are minimally invasive they are currently the most preferred method of treating disorders such as stroke, arterial stenosis, and aneurysms; however, the x-ray exposure to the patient during long image-guided interventional procedures could cause harmful effects such as cancer in the long run and even tissue damage in the short term. ROI fluoroscopy reduces patient dose by differentially attenuating the incident x-rays outside the region-of-interest. To reduce the noise in the dose-reduced regions previously recursive temporal filtering was successfully demonstrated for neurovascular interventions. However, in cardiac interventions, anatomical motion is significant and excessive recursive filtering could cause blur. In this work the effects of three noise-reduction schemes, including recursive temporal filtering, spatial mean filtering, and a combination of spatial and recursive temporal filtering, were investigated in a simulated ROI dose-reduced cardiac intervention. First a model to simulate the aortic arch and its movement was built. A coronary stent was used to simulate a bioprosthetic valve used in TAVR procedures and was deployed under dose-reduced ROI fluoroscopy during the simulated heart motion. The images were then retrospectively processed for noise reduction in the periphery, using recursive temporal filtering, spatial filtering and a combination of both. Quantitative metrics for all three noise reduction schemes are calculated and are presented as results. From these it can be concluded that with significant anatomical motion, a combination of spatial and recursive temporal filtering scheme is best suited for reducing the excess quantum noise in the periphery. This new noise-reduction technique in combination with ROI fluoroscopy has the potential for substantial patient-dose savings in cardiac interventions.

  16. Role of cardiac ultrafast cameras with CZT solid-state detectors and software developments on radiation absorbed dose reduction to the patients.

    PubMed

    Gunalp, Bengul

    2015-07-01

    Myocardial perfusion imaging (MPI) is one the most contributing nuclear medicine technique to the annual population dose. The purpose of this study is to compare radiation-absorbed doses to the patients examined by conventional cardiac SPECT (CSPECT) camera and ultrafast cardiac (UFC) camera with cadmium-zinc-telluride (CZT) solid-state detectors. Total injected activity was reduced by 50 % when both stress and rest images were acquired and by 75 % when only stress images were taken with UFC camera. As a result of this, the mean total effective dose was found significantly lower with UFC camera (2.2 ± 1.2 mSv) than CSPECT (7.7 ± 3.8 mSv) (p < 0.001). Further dose reduction was obtained by reducing equivocal test results and unnecessary additional examinations with UFC camera. Using UFC camera, MPI can be conveniently used for the detection of coronary artery disease (CAD) much less increasing annual population radiation dose as it had been before.

  17. Maintenance of remission following 2 years of standard treatment then dose reduction with abatacept in patients with early rheumatoid arthritis and poor prognosis

    PubMed Central

    Westhovens, Rene; Robles, Manuel; Ximenes, Antonio Carlos; Wollenhaupt, Jurgen; Durez, Patrick; Gomez-Reino, Juan; Grassi, Walter; Haraoui, Boulos; Shergy, William; Park, Sung-Hwan; Genant, Harry; Peterfy, Charles; Becker, Jean-Claude; Murthy, Bindu

    2015-01-01

    Objectives To evaluate maintenance of response while reducing intravenous abatacept dose from ∼10 mg/kg to ∼5 mg/kg in patients with early rheumatoid arthritis (RA) who achieved disease activity score (DAS)28 (erythrocyte sedimentation rate, ESR) <2.6. Methods This 1-year, multinational, randomised, double-blind substudy evaluated the efficacy and safety of ∼10 mg/kg and ∼5 mg/kg abatacept in patients with early RA with poor prognosis who had reached DAS28 (ESR) <2.6 at year 2 of the AGREE study. The primary outcome was time to disease relapse (defined as additional disease-modifying antirheumatic drugs, ≥2 courses high-dose steroids, return to open-label abatacept ∼10 mg/kg, or DAS28 (C reactive protein) ≥3.2 at two consecutive visits). Results 108 patients were randomised (∼10 mg/kg, n=58; ∼5 mg/kg, n=50). Three and five patients, respectively, discontinued, and four per group returned to open-label abatacept. Relapse over time and the proportion of patients relapsing were similar in both groups (31% (∼10 mg/kg) vs 34% (∼5 mg/kg); HR: 0.87 (95% CI 0.45 to 1.69)). Mean steady-state trough serum concentration for the ∼10 mg/kg group was 20.3–24.1 µg/mL, compared with 8.8–12.0 µg/mL for the ∼5 mg/kg group. Conclusions This exploratory study suggests that abatacept dose reduction may be an option in patients with poor prognosis early RA who achieve DAS28 (ESR) <2.6 after ≥1 year on abatacept (∼10 mg/kg). Trial registration number NCT00989235. PMID:25550337

  18. Toward time resolved 4D cardiac CT imaging with patient dose reduction: estimating the global heart motion

    NASA Astrophysics Data System (ADS)

    Taguchi, Katsuyuki; Segars, W. Paul; Fung, George S. K.; Tsui, Benjamin M. W.

    2006-03-01

    Coronary artery imaging with multi-slice helical computed tomography is a promising noninvasive imaging technique. The current major issues include the insufficient temporal resolution and large patient dose. We propose an image reconstruction method which provides a solution to both of the problems. The method uses an iterative approach repeating the following four steps until the difference between the two projection data sets falls below a certain criteria in step-4: 1) estimating or updating the cardiac motion vectors, 2) reconstructing the time-resolved 4D dynamic volume images using the motion vectors, 3) calculating the projection data from the current 4D images, 4) comparing them with the measured ones. In this study, we obtain the first estimate of the motion vector. We use the 4D NCAT phantom, a realistic computer model for the human anatomy and cardiac motions, to generate the dynamic fan-beam projection data sets as well to provide a known truth for the motion. Then, the halfscan reconstruction with the sliding time-window technique is used to generate cine images: f(t, r r). Here, we use one heart beat for each position r so that the time information is retained. Next, the magnitude of the first derivative of f(t, r r) with respect to time, i.e., |df/dt|, is calculated and summed over a region-of-interest (ROI), which is called the mean-absolute difference (MAD). The initial estimation of the vector field are obtained using MAD for each ROI. Results of the preliminary study are presented.

  19. Reduction of circulating regulatory T cells by intravenous high-dose interferon alfa-2b treatment in melanoma patients.

    PubMed

    Mozzillo, Nicola; Ascierto, Paolo

    2012-10-01

    High-dose interferon alfa-2b (IFNα-2b) is the only approved adjuvant systemic therapy for resected, high risk melanoma in the United States (Fecher and Flaherty, in Natl Compr Cancer Netw 7:295-304, 2009). Recently, two important meta-analyses of randomized trials (Wheatley et al., in J Clin Oncol, 2007; Mocellin et al. in J Natl Cancer Inst, 2010) investigating IFNα-2b versus observation in high risk melanoma patients, showed that adjuvant IFNα-2b has an impact both on relapse-free survival (RFS) and overall survival (OS) independently by dosage, duration and route compared with observation in high risk melanoma patients. Despite of an absolute benefits of 3 % (Wheatley et al., in J Clin Oncol, 2007), this treatment is associated with significant toxicity, which impacts on patient quality of life. A better understanding of the mechanism of action may help to potentiate the clinical efficacy and reduce the toxicity of IFNα-2b/Peg-IFNα-2b. Numerous studies suggest that interferon's mechanism of action in melanoma is primarily immunomodulatory (Table 1) (de La Salmoniere, in Clin Cancer Res 6:4713-4718, 2000; Stuckert, in J Clin Oncol 25:8506, 2007; Gogas et al., in N Engl J Med 354:709-718, 2006; Moschos et al., in J Clin Oncol 24:3164-3171, 2006; Ascierto and Kirkwood, in J Transl Med 6:62, 2008) Recent efforts to elucidate the mechanism of action for interferon have focused upon signal transducers and activators of transcription (STAT) (Simons et al., in J Transl Med 9:52, 2011) signaling and immunoregulatory responses mediated by regulatory T cells (Tregs) (Wang et al., in Clin Cancer Res 13:1523-1531, 2007; Clin Cancer Res 14:8314-8320, 2008). Tregs are a suppressive CD4+ T cell population that is present, along with primed effector T cells, in tumor and tumor-draining lymph nodes (Hiura et al. in J Immunol 175:5058-5066, 2005). Tregs express high levels of surface antigens such as CD25, cytotoxic T lymphocyte associated antigen 4 (CTLA-4), and

  20. Transcriptional effects of gene dose reduction

    PubMed Central

    2014-01-01

    Large-scale gene dose reductions usually lead to abnormal phenotypes or death. However, male mammals, Drosophila, and Caenorhabditis elegans have only one X chromosome and thus can be considered as monosomic for a major chromosome. Despite the deleterious effects brought about by such gene dose reduction in the case of an autosome, X chromosome monosomy in males is natural and innocuous. This is because of the nearly full transcriptional compensation for X chromosome genes in males, as opposed to no or partial transcriptional compensation for autosomal one-dose genes arising due to deletions. Buffering, the passive absorption of disturbance due to enzyme kinetics, and feedback responses triggered by expression change contribute to partial compensation. Feed-forward mechanisms, which are active responses to genes being located on the X, rather than actual gene dose are important contributors to full X chromosome compensation. In the last decade, high-throughput techniques have provided us with the tools to effectively and quantitatively measure the small-fold transcriptional effects of dose reduction. This is leading to a better understanding of compensatory mechanisms. PMID:24581086

  1. Strategies for reduction of radiation dose in cardiac multislice CT.

    PubMed

    Paul, Jean-François; Abada, Hicham T

    2007-08-01

    Because cardiac computed tomography (CT) (mainly coronary CT angiography) is a very promising technique, used more and more for coronary artery evaluation, the benefits and risks of this new low-invasive technique must be balanced. Radiation dose is a major concern for coronary CT angiography, especially in case of repeated examinations or in particular subgroups of patients (for example young female patients). Radiation dose to patient tends to increase from 16- to 64-slice CT. Radiation exposure in ECG-gated acquisitions may reach up to 40 mSv; considerable differences are attributable to the performance of CT machines, to technical dose-sparing tools, but also to radiological habits. Setting radiation dose at the lowest level possible should be a constant goal for the radiologist. Current technological tools are detailed in regard to their efficiency. Optimisation is necessary, by a judicious use of technological tools and also by individual adaptation of kV or mAs. This paper reviews the different current strategies for radiation dose reduction, keeping image quality constant. Data from the literature are discussed, and future technological developments are considered in regards to radiation dose reduction. The particular case of paediatric patients with congenital heart disease is also addressed.

  2. Impact of Safety-Related Dose Reductions or Discontinuations on Sustained Virologic Response in HCV-Infected Patients: Results from the GUARD-C Cohort

    PubMed Central

    Foster, Graham R.; Coppola, Carmine; Derbala, Moutaz; Ferenci, Peter; Orlandini, Alessandra; Reddy, K. Rajender; Tallarico, Ludovico; Shiffman, Mitchell L.; Ahlers, Silke; Bakalos, Georgios; Hassanein, Tarek

    2016-01-01

    Background Despite the introduction of direct-acting antiviral agents for chronic hepatitis C virus (HCV) infection, peginterferon alfa/ribavirin remains relevant in many resource-constrained settings. The non-randomized GUARD-C cohort investigated baseline predictors of safety-related dose reductions or discontinuations (sr-RD) and their impact on sustained virologic response (SVR) in patients receiving peginterferon alfa/ribavirin in routine practice. Methods A total of 3181 HCV-mono-infected treatment-naive patients were assigned to 24 or 48 weeks of peginterferon alfa/ribavirin by their physician. Patients were categorized by time-to-first sr-RD (Week 4/12). Detailed analyses of the impact of sr-RD on SVR24 (HCV RNA <50 IU/mL) were conducted in 951 Caucasian, noncirrhotic genotype (G)1 patients assigned to peginterferon alfa-2a/ribavirin for 48 weeks. The probability of SVR24 was identified by a baseline scoring system (range: 0–9 points) on which scores of 5 to 9 and <5 represent high and low probability of SVR24, respectively. Results SVR24 rates were 46.1% (754/1634), 77.1% (279/362), 68.0% (514/756), and 51.3% (203/396), respectively, in G1, 2, 3, and 4 patients. Overall, 16.9% and 21.8% patients experienced ≥1 sr-RD for peginterferon alfa and ribavirin, respectively. Among Caucasian noncirrhotic G1 patients: female sex, lower body mass index, pre-existing cardiovascular/pulmonary disease, and low hematological indices were prognostic factors of sr-RD; SVR24 was lower in patients with ≥1 vs. no sr-RD by Week 4 (37.9% vs. 54.4%; P = 0.0046) and Week 12 (41.7% vs. 55.3%; P = 0.0016); sr-RD by Week 4/12 significantly reduced SVR24 in patients with scores <5 but not ≥5. Conclusions In conclusion, sr-RD to peginterferon alfa-2a/ribavirin significantly impacts on SVR24 rates in treatment-naive G1 noncirrhotic Caucasian patients. Baseline characteristics can help select patients with a high probability of SVR24 and a low probability of sr-RD with

  3. Impact of new technologies on dose reduction in CT.

    PubMed

    Lee, Ting-Yim; Chhem, Rethy K

    2010-10-01

    The introduction of slip ring technology enables helical CT scanning in the late 1980's and has rejuvenated CT's role in diagnostic imaging. Helical CT scanning has made possible whole body scanning in a single breath hold and computed tomography angiography (CTA) which has replaced invasive catheter based angiography in many cases because of its easy of operation and lesser risk to patients. However, a series of recent articles and accidents have heightened the concern of radiation risk from CT scanning. Undoubtedly, the radiation dose from CT studies, in particular, CCTA studies, are among the highest dose studies in diagnostic imaging. Nevertheless, CT has remained the workhorse of diagnostic imaging in emergent and non-emergent situations because of their ubiquitous presence in medical facilities from large academic to small regional hospitals and their round the clock accessibility due to their ease of use for both staff and patients as compared to MR scanners. The legitimate concern of radiation dose has sparked discussions on the risk vs benefit of CT scanning. It is recognized that newer CT applications, like CCTA and perfusion, will be severely curtailed unless radiation dose is reduced. This paper discusses the various hardware and software techniques developed to reduce radiation dose to patients in CT scanning. The current average effective dose of a CT study is ∼10 mSv, with the implementation of dose reduction techniques discussed herein; it is realistic to expect that the average effective dose may be decreased by 2-3 fold.

  4. Monte Carlo study of the potential reduction in out-of-field dose using a patient-specific aperture in pencil beam scanning proton therapy.

    PubMed

    Dowdell, Stephen J; Clasie, Benjamin; Depauw, Nicolas; Metcalfe, Peter; Rosenfeld, Anatoly B; Kooy, Hanne M; Flanz, Jacob B; Paganetti, Harald

    2012-05-21

    This study is aimed at identifying the potential benefits of using a patient-specific aperture in proton beam scanning. For this purpose, an accurate Monte Carlo model of the pencil beam scanning (PBS) proton therapy (PT) treatment head at Massachusetts General Hospital (MGH) was developed based on an existing model of the passive double-scattering (DS) system. The Monte Carlo code specifies the treatment head at MGH with sub-millimeter accuracy. The code was configured based on the results of experimental measurements performed at MGH. This model was then used to compare out-of-field doses in simulated DS treatments and PBS treatments. For the conditions explored, the penumbra in PBS is wider than in DS, leading to higher absorbed doses and equivalent doses adjacent to the primary field edge. For lateral distances greater than 10 cm from the field edge, the doses in PBS appear to be lower than those observed for DS. We found that placing a patient-specific aperture at nozzle exit during PBS treatments can potentially reduce doses lateral to the primary radiation field by over an order of magnitude. In conclusion, using a patient-specific aperture has the potential to further improve the normal tissue sparing capabilities of PBS.

  5. SU-E-J-243: Possibility of Exposure Dose Reduction of Cone-Beam Computed Tomography in An Image Guided Patient Positioning System by Using Various Noise Suppression Filters

    SciTech Connect

    Kamezawa, H; Arimura, H; Ohki, M; Shirieda, K; Kameda, N

    2014-06-01

    Purpose: To investigate the possibility of exposure dose reduction of the cone-beam computed tomography (CBCT) in an image guided patient positioning system by using 6 noise suppression filters. Methods: First, a reference dose (RD) and low-dose (LD)-CBCT (X-ray volume imaging system, Elekta Co.) images were acquired with a reference dose of 86.2 mGy (weighted CT dose index: CTDIw) and various low doses of 1.4 to 43.1 mGy, respectively. Second, an automated rigid registration for three axes was performed for estimating setup errors between a planning CT image and the LD-CBCT images, which were processed by 6 noise suppression filters, i.e., averaging filter (AF), median filter (MF), Gaussian filter (GF), bilateral filter (BF), edge preserving smoothing filter (EPF) and adaptive partial median filter (AMF). Third, residual errors representing the patient positioning accuracy were calculated as an Euclidean distance between the setup error vectors estimated using the LD-CBCT image and RD-CBCT image. Finally, the relationships between the residual error and CTDIw were obtained for 6 noise suppression filters, and then the CTDIw for LD-CBCT images processed by the noise suppression filters were measured at the same residual error, which was obtained with the RD-CBCT. This approach was applied to an anthropomorphic pelvic phantom and two cancer patients. Results: For the phantom, the exposure dose could be reduced from 61% (GF) to 78% (AMF) by applying the noise suppression filters to the CBCT images. The exposure dose in a prostate cancer case could be reduced from 8% (AF) to 61% (AMF), and the exposure dose in a lung cancer case could be reduced from 9% (AF) to 37% (AMF). Conclusion: Using noise suppression filters, particularly an adaptive partial median filter, could be feasible to decrease the additional exposure dose to patients in image guided patient positioning systems.

  6. Dose reduction using a dynamic, piecewise-linear attenuator

    SciTech Connect

    Hsieh, Scott S.; Fleischmann, Dominik; Pelc, Norbert J.

    2014-02-15

    Purpose: The authors recently proposed a dynamic, prepatient x-ray attenuator capable of producing a piecewise-linear attenuation profile customized to each patient and viewing angle. This attenuator was intended to reduce scatter-to-primary ratio (SPR), dynamic range, and dose by redistributing flux. In this work the authors tested the ability of the attenuator to reduce dose and SPR in simulations. Methods: The authors selected four clinical applications, including routine full field-of-view scans of the thorax and abdomen, and targeted reconstruction tasks for an abdominal aortic aneurysm and the pancreas. Raw data were estimated by forward projection of the image volume datasets. The dynamic attenuator was controlled to reduce dose while maintaining peak variance by solving a convex optimization problem, assuminga priori knowledge of the patient anatomy. In targeted reconstruction tasks, the noise in specific regions was given increased weighting. A system with a standard attenuator (or “bowtie filter”) was used as a reference, and used either convex optimized tube current modulation (TCM) or a standard TCM heuristic. The noise of the scan was determined analytically while the dose was estimated using Monte Carlo simulations. Scatter was also estimated using Monte Carlo simulations. The sensitivity of the dynamic attenuator to patient centering was also examined by shifting the abdomen in 2 cm intervals. Results: Compared to a reference system with optimized TCM, use of the dynamic attenuator reduced dose by about 30% in routine scans and 50% in targeted scans. Compared to the TCM heuristics which are typically used withouta priori knowledge, the dose reduction is about 50% for routine scans. The dynamic attenuator gives the ability to redistribute noise and variance and produces more uniform noise profiles than systems with a conventional bowtie filter. The SPR was also modestly reduced by 10% in the thorax and 24% in the abdomen. Imaging with the dynamic

  7. MO-F-CAMPUS-I-04: Patient Eye-Lens Dose Reduction in Routine Brain CT Examinations Using Organ-Based Tube Current Modulation and In-Plane Bismuth Shielding

    SciTech Connect

    Tsai, Hui-Yu; Liao, Ying-Lan; Chen, Jun-Rong

    2015-06-15

    Purpose: The purpose of this study is to assess eye-lens dose for patients who underwent brain CT examinations using two dose reduction Methods: organ-based tube current modulation (OBTCM) and in-plane bismuth shielding method. Methods: This study received institutional review board approval; written informed consent to participate was obtained from all patients. Ninety patients who underwent the routine brain CT examination were randomly assigned to three groups, ie. routine, OBTCM, and bismuth shield. The OBTCM technique reduced the tube current when the X-ray tube rotates in front of patients’ eye-lens region. The patients in the bismuth shield group were covered one-ply bismuth shield in the eyes’ region. Eye-lens doses were measured using TLD-100H chips and the total effective doses were calculated using CT-Expo according to the CT scanning parameters. The surface doses for patients at off-center positions were assessed to evaluate the off-centering effect. Results: Phantom measurements indicates that OBTCM technique could reduced by 26% to 28% of the surface dose to the eye lens, and increased by 25% of the surface dose at the opposed incident direction at the angle of 180°. Patients’ eye-lens doses were reduced 16.9% and 30.5% dose of bismuth shield scan and OBTCM scan, respectively compared to the routine scan. The eye-lens doses were apparently increased when the table position was lower than isocenter. Conclusion: Reducing the dose to the radiosensitive organs, such as eye lens, during routine brain CT examinations could lower the radiation risks. The OBTCM technique and in-plane bismuth shielding could be used to reduce the eye-lens dose. The eye-lens dose could be effectively reduced using OBTCM scan without interfering the diagnostic image quality. Patient position relative the CT gantry also affects the dose level of the eye lens. This study was supported by the grants from the Ministry of Science and Technology of Taiwan (MOST103-2314-B-182

  8. Exposure to Non-Therapeutic INR in a High Risk Cardiovascular Patient: Potential Hazard Reduction with Genotype-guided Warfarin (Coumadin®) Dosing

    PubMed Central

    Rodríguez-Vélez, Rosángela; Ortiz-Rivera, Oscar J.; Bower, Bruce; Gorowski, Krystyna; Windemuth, Andreas; Villagra, David; Kocherla, Mohan; Seip, Richard L; D'Agostino, Darrin; Vergara, Cunegundo; Ruaño, Gualberto; Duconge, Jorge

    2013-01-01

    A case to illustrate the utility of genetic screening in warfarin (Coumadin®) management is reported. A 45 year-old woman of Puerto Rican ancestry was admitted to the emergency room twice within one month with chest pain. She was diagnosed with congestive heart failure, which was stabilized both times. At her second release, warfarin therapy was initiated at 5 mg/day to prevent thrombus formation and was lowered to 3.75 mg/day at day 7 by her primary physician. International Normalized Ratio (INR) test results in the follow-up period at days 1, 7, and 10 of warfarin therapy were 4.5, 6.5, and 7.3, respectively—far in excess of the therapeutic range, despite the lower dosage in effect from day 7 onward. the patient achieved target INR over the next 43 days after downward adjustment of the dose to a dose of 1.5 mg/day by trial and error. DNA-typing specific for the CYP2C9*2, *3, *4, *5, *6 alleles and seven variants in the VKORC1 gene, including the VKORC1-1639 G>A polymorphism, revealed the presence of combinatorial CYP2C9*2/*3 and VKORC1-1639 G/A genotypes in this patient. Entering the patient's demographic and genotype status data into independent algorithms available in the public domain to predict effective warfarin dose yielded predicted doses which ranged from 1.5 to 1.8 mg/day. Notably, the prediction of 1.5 mg/day, which was generated by the online resource www.warfarindosing.org, coincided with the patient's actual effective warfarin dose. We conclude that the rapid rise in INR observed upon the initiation of warfarin therapy and the final effective warfarin dose of 1.5 mg/day, are attributable in some part to the presence of two minor alleles in CYP2C9, which together significantly reduce warfarin metabolism. Warfarin genotyping can therefore inform the clinician of the predicted effective warfarin dose. the results highlight the potential for warfarin genetic testing to improve patient care. PMID:21261182

  9. Patient Dose Management: Focus on Practical Actions

    PubMed Central

    2016-01-01

    Medical radiation is a very important part of modern medicine, and should be only used when needed and optimized. Justification and optimization of radiation examinations must be performed. The first step of reduction of medical exposure is to know the radiation dose in currently performed examinations. This review covers radiation units, how various imaging modalities report dose, and the current status of radiation dose reports and legislation. Also, practical tips that can be applied to clinical practice are introduced. Afterwards, the importance of radiology exposure related education is emphasized and the current status of education for medical personal and the public is explained, and appropriate education strategies are suggested. Commonly asked radiation dose related example questions and answers are provided in detail to allow medical personnel to answer patients. Lastly, we talk about computerized programs that can be used in medical facilities for managing patient dose. While patient dose monitoring and management should be used to decrease and optimize overall radiation dose, it should not be used to assess individual cancer risk. One must always remember that medically justified examinations should always be performed, and unneeded examinations should be avoided in the first place. PMID:26908988

  10. Paediatric dose reduction with the introduction of digital fluorography.

    PubMed

    Mooney, R B; McKinstry, J

    2001-01-01

    Fluoroscopy guided examinations in a paediatric X ray department were initially carried out on a unit that used a conventional screen-film combination for spot-films. A new fluoroscopy unit was installed with the facilities of digital fluorography and last image hold. Comparison of equipment performance showed that the dose per image for screen-film and digital fluorography was 3 microGy and 0.4 microGy, respectively. Although the screen-film had superior image quality, the department's radiologist confirmed that digital fluorography provided a diagnostic image. Patient dose measurements showed that introduction of the new unit caused doses to fall by an average of 70%, although fluoroscopy time had not changed significantly. The new unit produced 40% less air kerma during fluoroscopy. The remaining 30% reduction in dose was due to the introduction of digital fluorography and last image hold facilities. It is concluded that the use of digital fluorography can be an effective way of reducing paediatric dose.

  11. Nutritional Status, Body Surface, and Low Lean Body Mass/Body Mass Index Are Related to Dose Reduction and Severe Gastrointestinal Toxicity Induced by Afatinib in Patients With Non-Small Cell Lung Cancer

    PubMed Central

    De la Torre-Vallejo, Martha; López-Macías, Diego; Orta, David; Turcott, Jenny; Macedo-Pérez, Eleazar-Omar; Sánchez-Lara, Karla; Ramírez-Tirado, Laura-Alejandra; Baracos, Vickie E.

    2015-01-01

    Background. The main reason for dose reduction of afatinib is gastrointestinal toxicity (GT). In a phase II study, we analyzed anthropometrical, nutritional, and biochemical factors associated with GT induced by afatinib. Materials and Methods. Patients diagnosed with non-small cell lung cancer who progressed to prior chemotherapy received 40 mg of afatinib. Malnutrition was determined by Subjective Global Assessment, and lean body mass (LBM) was determined by computed tomography scan analysis using a pre-established Hounsfield unit threshold. Toxicity was obtained during four cycles by Common Terminology Criteria for Adverse Events. Results. Eighty-four patients were enrolled. Afatinib was administered as the second, third, and fourth line of treatment in 54.8%, 38.1%, and 7.12% of patients, respectively. Severe diarrhea, mucositis, and overall severe GT were present in 38.9%, 28.8%, and 57.5%, respectively. Of the patients, 50% developed dose-limiting toxicity (DLT). Patients with malnutrition have higher risk for severe GT. Patients with lower LBM and body mass index developed more DLT (71.4% vs. 18.8%). Conclusion. Malnutrition is associated with a higher risk of severe GT induced by afatinib. Determination of nutritional status and body composition are helpful in identifying patients at higher risk of severe GT and could allow initiating treatment with lower doses according to tolerance. Implications for Practice: Body composition analysis, specifically lean body mass quantification, and nutritional status assessment are significant clinical variables to take into account when assessing oncological patients. This study on patients with non-small cell lung cancer treated with afatinib showed the important impact that malnutrition and low lean body mass have on the risk for developing dose-limiting toxicity and severe gastrointestinal toxicity. Still more research needs to be done to explore dose adjustment according to lean body mass, especially in drugs that

  12. Antimicrobial Dose in Obese Patient

    PubMed Central

    Kassab, Sawsan; Syed Sulaiman, Syed Azhar; Abdul Aziz, Noorizan

    2007-01-01

    Introduction Obesity is a chronic disease that has become one of major public health issue in Malaysia because of its association with other disease states including cardiovascular disease and diabetes. Despite continuous efforts to educate the public about the health risks associated with obesity, prevalence of the disease continues to increase. Dosing of many medications are based on weight, limited data are available on how antimicrobial agents should be dosed in obesity. The aim of this case presentation is to discuss dose of antibiotic in obese patient. Case report: Patient: GMN, Malay, Female, 45 year old, 150kg, transferred from medical ward to ICU with problems of fever, orthopnea, sepsis secondary to nosocomial pneumonia. She was admitted to hospital a week ago for SOB on exertion, cyanosis, mildly dyspneic, somasthenia, bilateral ankle swelling. There was no fever, cough, chest pain, clubbing, flapping tremor. Her grand father has pre-morbid history of obesity, HPT, DM and asthma. She was non alcoholic, smoker, and not on diet control. The diagnosis Pickwickian syndrome was made. Patient was treated with IV Dopamine 11mcg/kg/min, IV Morphine 4mg/h. IV GTN 15mcg/min, IV Ca gluconate 10g/24h for 3/7, IV Zantac 50mg tds, IV Augmentin 1.2g tds, IV Lasix 40mg od, IV Plasil 10mg tds, S.c heparin 5000IU bd. patient become stable and moved to medical ward to continue her treatment. Discussion: The altered physiologic function seen in obese patients is a concern in patients receiving antimicrobial agents because therapeutic outcomes depend on achieving a minimum inhibitory concentration (MIC). The therapeutic effect of any drug can be altered when any of the 4 pharmacokinetic processes (absorption, distribution, metabolism, or elimination) are altered. Decreased blood flow rates and increased renal clearance in obese patients can affect drug distribution and elimination. Changes in serum protein levels can change the metabolism and distribution of drugs that are

  13. Pectus excavatum: current imaging techniques and opportunities for dose reduction.

    PubMed

    Sarwar, Zahir U; DeFlorio, Robert; O'Connor, Stephen C

    2014-08-01

    Pectus excavatum (PE) is the most common congenital chest wall deformity in children. It affects 1 in every 300-1000 live births with a male to female ratio of 5:1. Most of the patients present in their first year of life. During the teenage years, patients may have exercise intolerance and psychological strain because of their chest wall deformity. The Nuss and Ravitch procedures are established methods of surgical correction of PE. An index of severity known best as the Haller index, typically evaluated with computed tomography scan, when measuring greater than 3.2 is considered to indicate moderate or severe PE and is a prerequisite for third-party insurance reimbursement for these corrective procedures. This article reviews the clinical features of PE, the role of imaging, and the opportunities for radiation dose reduction.

  14. A patient-specific therapeutic approach for tumour cell population extinction and drug toxicity reduction using control systems-based dose-profile design

    PubMed Central

    2013-01-01

    Background When anti-tumour therapy is administered to a tumour-host environment, an asymptotic tapering extremity of the tumour cell distribution is noticed. This extremity harbors a small number of residual tumour cells that later lead to secondary malignances. Thus, a method is needed that would enable the malignant population to be completely eliminated within a desired time-frame, negating the possibility of recurrence and drug-induced toxicity. Methods In this study, we delineate a computational procedure using the inverse input-reconstruction approach to calculate the unknown drug stimulus input, when one desires a known output tissue-response (full tumour cell elimination, no excess toxicity). The asymptotic extremity is taken care of using a bias shift of tumour-cell distribution and guided control of drug administration, with toxicity limits enforced, during mutually-synchronized chemotherapy (as Temozolomide) and immunotherapy (Interleukin-2 and Cytotoxic T-lymphocyte). Results Quantitative modeling is done using representative characteristics of rapidly and slowly-growing tumours. Both were fully eliminated within 2 months with checks for recurrence and toxicity over a two-year time-line. The dose-time profile of the therapeutic agents has similar features across tumours: biphasic (lymphocytes), monophasic (chemotherapy) and stationary (interleukin), with terminal pulses of the three agents together ensuring elimination of all malignant cells. The model is then justified with clinical case studies and animal models of different neurooncological tumours like glioma, meningioma and glioblastoma. Conclusion The conflicting oncological objectives of tumour-cell extinction and host protection can be simultaneously accommodated using the techniques of drug input reconstruction by enforcing a bias shift and guided control over the drug dose-time profile. For translational applicability, the procedure can be adapted to accommodate varying patient parameters

  15. Device for the reduction of population dose

    SciTech Connect

    Kihara, T.; Uchinoumi, K.; Akagi, F.; Antoku, S.

    1982-06-01

    Conventional dental radiographic procedures do not permit direct visualization of the radiation field or the central ray. As a result, it is necessary to use a beam diameter larger than the film in order to prevent an unnecessarily high number of cone cuts or other errors during visual alignment of the cone and film. The modification of a conventional dental x-ray cone which permits the central ray to be depicted by a beam of light is described. The use of the device significantly reduced the number of cone cuts, even when small beam diameters were used. Visualization of the central ray improved radiographic accuracy and has the potential to significantly reduce the over-all dose to the population by reducing the size of the field used for dental radiography.

  16. Order of magnitude reduction of fluoroscopic x-ray dose

    NASA Astrophysics Data System (ADS)

    Bal, Abhinav; Robert, Normand; Machan, Lindsay; Deutsch, Meir; Kisselgoff, David; Babyn, Paul; Rowlands, John A.

    2012-03-01

    The role of fluoroscopic imaging is critical for diagnostic and image guided therapy. However, fluoroscopic imaging can require significant radiation leading to increased cancer risk and non-stochastic effects such as radiation burns. Our purpose is to reduce the exposure and dose to the patient by an order of magnitude in these procedures by use of the region of interest method. Method and Materials: Region of interest fluoroscopy (ROIF) uses a partial attenuator. The central region of the image has full exposure while the image periphery, there to provide context only, has a reduced exposure rate. ROIF using a static partial attenuator has been shown in our previous studies to reduce the dose area product (DAP) to the patient by at least 2.5 times. Significantly greater reductions in DAP would require improvements in flat panel detectors performance at low x-ray exposures or a different x-ray attenuation strategy. Thus we have investigated a second, dynamic, approach. We have constructed an x-ray shutter system allowing a normal x-ray exposure in the region of interest while reducing the number of x-ray exposures in the periphery through the rapid introduction, positioning and removal of an x-ray attenuating shutter to block radiation only for selected frames. This dynamic approach eliminates the DQE(0) loss associated with the use of static partial attenuator applied to every frame thus permitting a greater reduction in DAP. Results: We have compared the two methods by modeling and determined their fundamental limits.

  17. Dose reduction with adaptive bolus chasing computed tomography angiography.

    PubMed

    Cai, Zhijun; Bai, Er-Wei; Wang, Ge; Sharafuddin, Melhem J; Abada, Hicham T

    2010-01-01

    Computed Tomography (CT) has become an effective diagnosis and evaluating tool in clinical; however, its radiation exposure has drawn great attention as more and more CT scans are performed every year. How to reduce the radiation dose and meanwhile keep the resultant CT images diagnosable becomes an important research topic. In this paper, we propose a dose reduction approach along with the adaptive bolus chasing CT Angiography (CTA) techniques, which are capable of tracking the contrast bolus peak over all the blood vessel segments during the CTA scan. By modulating the tube current (and collimator width) online, we can reduce the total radiation dose and maintain the contrast to noise ratio (CNR) of the blood vessel. Numerical experiments on reference DSA data sets show that by using the proposed dose reduction method, the effective radiation dose can be saved about 39%.

  18. Dose Reduction with Adaptive Bolus Chasing Computed Tomography Angiography

    PubMed Central

    Cai, Zhijun; Bai, Er-Wei; Wang, Ge; Sharafuddin, Melhem J.; Abada, Hicham T.

    2010-01-01

    Computed Tomography (CT) has become an effective diagnosis and evaluating tool in clinical; however, its radiation exposure has drawn great attention as more and more CT scans are performed every year. How to reduce the radiation dose and meanwhile keep the resultant CT images diagnosable becomes an important research topic. In this paper, we propose a dose reduction approach along with the adaptive bolus chasing CT Angiography (CTA) techniques, which are capable of tracking the contrast bolus peak over all the blood vessel segments during the CTA scan. By modulating the tube current (and collimator width) online, we can reduce the total radiation dose and maintain the contrast to noise ratio (CNR) of the blood vessel. Numerical experiments on reference DSA data sets show that by using the proposed dose reduction method, the effective radiation dose can be saved about 39%. PMID:20421701

  19. Low-dose digital urography in the pregnant patient

    SciTech Connect

    Albert, S.A.; Richter, J.O.; Rosenfield, A.T.

    1987-04-01

    In the pregnant patient when visualization of the ureters is requested, excretory urography is often ordered. We propose the use of digital radiography using single exposure as an alternative to conventional urography. This technique allows significant dose reduction while visualizing the entire urinary tract. It can be performed on most current-generation computerized tomographic scanners. In addition to dose reduction, the ability to manipulate, magnify, and avoid repeat exposures makes this an attractive alternative to the conventional film-screen technique.

  20. SU-E-T-802: Verification of Implanted Cardiac Pacemaker Doses in Intensity-Modulated Radiation Therapy: Dose Prediction Accuracy and Reduction Effect of a Lead Sheet

    SciTech Connect

    Lee, J; Chung, J

    2015-06-15

    Purpose: To verify delivered doses on the implanted cardiac pacemaker, predicted doses with and without dose reduction method were verified using the MOSFET detectors in terms of beam delivery and dose calculation techniques in intensity-modulated radiation therapy (IMRT). Methods: The pacemaker doses for a patient with a tongue cancer were predicted according to the beam delivery methods [step-and-shoot (SS) and sliding window (SW)], intensity levels for dose optimization, and dose calculation algorithms. Dosimetric effects on the pacemaker were calculated three dose engines: pencil-beam convolution (PBC), analytical anisotropic algorithm (AAA), and Acuros-XB. A lead shield of 2 mm thickness was designed for minimizing irradiated doses to the pacemaker. Dose variations affected by the heterogeneous material properties of the pacemaker and effectiveness of the lead shield were predicted by the Acuros-XB. Dose prediction accuracy and the feasibility of the dose reduction strategy were verified based on the measured skin doses right above the pacemaker using mosfet detectors during the radiation treatment. Results: The Acuros-XB showed underestimated skin doses and overestimated doses by the lead-shield effect, even though the lower dose disagreement was observed. It led to improved dose prediction with higher intensity level of dose optimization in IMRT. The dedicated tertiary lead sheet effectively achieved reduction of pacemaker dose up to 60%. Conclusion: The current SS technique could deliver lower scattered doses than recommendation criteria, however, use of the lead sheet contributed to reduce scattered doses.Thin lead plate can be a useful tertiary shielder and it could not acuse malfunction or electrical damage of the implanted pacemaker in IMRT. It is required to estimate more accurate scattered doses of the patient with medical device to design proper dose reduction strategy.

  1. Inter- and Intrafractional Movement-Induced Dose Reduction of Prostate Target Volume in Proton Beam Treatment

    SciTech Connect

    Yoon, Myonggeun; Kim, Dongwook; Shin, Dong Ho; Park, Sung Yong Lee, Se Byeong; Kim, Dae Yong; Kim, Joo Young; Pyo, Hong Ryull; Cho, Kwan Ho

    2008-07-15

    Purpose: To quantify proton radiotherapy dose reduction in the prostate target volume because of the three-dimensional movement of the prostate based on an analysis of dose-volume histograms (DVHs). Methods and Materials: Twelve prostate cancer patients underwent scanning in supine position, and a target contour was delineated for each using a proton treatment planning system. To simulate target movement, the contour was displaced from 3 to 15 mm in 3-mm intervals in the superior-to-inferior (SI), inferior-to-superior (IS), anterior-to-posterior (AP), posterior-to-anterior (PA), and left-to-right (LR) directions. Results: For both intra- and interfractional movements, the average coverage index and conformity index of the target were reduced in all directions. For interfractional movements, the magnitude of dose reduction was greater in the LR direction than in the AP, PA, SI. and IS directions. Although the reduction of target dose was proportional to the magnitude of intrafractional movement in all directions, a proportionality between dose reduction and the magnitude of interfractional target movement was clear only in the LR direction. Like the coverage index and conformity index, the equivalent uniform dose and homogeneity index showed similar reductions for both types of target movements. Conclusions: Small target movements can significantly reduce target proton radiotherapy dose during treatment of prostate cancer patients. Attention should be given to interfractional target movement along the longitudinal direction, as image-guided radiotherapy may be ineffective if margins are not sufficient.

  2. Dose reduction improvements in storage basins of spent nuclear fuel

    SciTech Connect

    Huang, Fan-Hsiung F.

    1997-08-13

    Spent nuclear fuel in storage basins at the Hanford Site has corroded and contaminated basin water, which has leaked into the soil; the fuel also had deposited a layer of radioactive sludge on basin floors. The SNF is to be removed from the basins to protect the nearby Columbia River. Because the radiation level is high, measures have been taken to reduce the background dose rate to as low as reasonably achievable (ALARA) to prevent radiation doses from becoming the limiting factor for removal of the SW in the basins to long-term dry storage. All activities of the SNF Project require application of ALARA principles for the workers. On the basis of these principles dose reduction improvements have been made by first identifying radiological sources. Principal radiological sources in the basin are basin walls, basin water, recirculation piping and equipment. Dose reduction activities focus on cleaning and coating basin walls to permit raising the water level, hydrolasing piping, and placing lead plates. In addition, the transfer bay floor will be refinished to make decontamination easier and reduce worker exposures in the radiation field. The background dose rates in the basin will be estimated before each task commences and after it is completed; these dose reduction data will provide the basis for cost benefit analysis.

  3. Objective and Longitudinal Assessment of Dermatitis After Postoperative Accelerated Partial Breast Irradiation Using High-Dose-Rate Interstitial Brachytherapy in Patients With Breast Cancer Treated With Breast Conserving Therapy: Reduction of Moisture Deterioration by APBI

    SciTech Connect

    Tanaka, Eiichi; Yamazaki, Hideya; Yoshida, Ken; Takenaka, Tadashi; Masuda, Norikazu; Kotsuma, Tadayuki; Yoshioka, Yasuo; Inoue, Takehiro

    2011-11-15

    Purpose: To objectively evaluate the radiation dermatitis caused by accelerated partial breast irradiation (APBI) using high-dose-rate interstitial brachytherapy. Patients and Methods: The skin color and moisture changes were examined using a newly installed spectrophotometer and corneometer in 22 patients who had undergone APBI using open cavity implant high-dose-rate interstitial brachytherapy (36 Gy in six fractions) and compared with the corresponding values for 44 patients in an external beam radiotherapy (EBRT) control group (50-60 Gy in 25-30 fractions within 5-6 weeks) after breast conserving surgery. Results: All values changed significantly as a result of APBI. The extent of elevation in a Asterisk-Operator (reddish) and reduction in L Asterisk-Operator (black) values caused by APBI were similar to those for EBRT, with slightly delayed recovery for 6-12 months after treatment owing to the surgical procedure. In contrast, only APBI caused a change in the b Asterisk-Operator values, and EBRT did not, demonstrating that the reduction in b Asterisk-Operator values (yellowish) depends largely on the surgical procedure. The changes in moisture were less severe after APBI than after EBRT, and the recovery was more rapid. The toxicity assessment using the Common Toxicity Criteria, version 3, showed that all dermatitis caused by APBI was Grade 2 or less. Conclusion: An objective analysis can quantify the effects of APBI procedures on color and moisture cosmesis. The radiation dermatitis caused by APBI using the present schedule showed an equivalent effect on skin color and a less severe effect on moisture than the effects caused by standard EBRT.

  4. Method for inserting noise in digital mammography to simulate reduction in radiation dose

    NASA Astrophysics Data System (ADS)

    Borges, Lucas R.; de Oliveira, Helder C. R.; Nunes, Polyana F.; Vieira, Marcelo A. C.

    2015-03-01

    The quality of clinical x-ray images is closely related to the radiation dose used in the imaging study. The general principle for selecting the radiation is ALARA ("as low as reasonably achievable"). The practical optimization, however, remains challenging. It is well known that reducing the radiation dose increases the quantum noise, which could compromise the image quality. In order to conduct studies about dose reduction in mammography, it would be necessary to acquire repeated clinical images, from the same patient, with different dose levels. However, such practice would be unethical due to radiation related risks. One solution is to simulate the effects of dose reduction in clinical images. This work proposes a new method, based on the Anscombe transformation, which simulates dose reduction in digital mammography by inserting quantum noise into clinical mammograms acquired with the standard radiation dose. Thus, it is possible to simulate different levels of radiation doses without exposing the patient to new levels of radiation. Results showed that the achieved quality of simulated images generated with our method is the same as when using other methods found in the literature, with the novelty of using the Anscombe transformation for converting signal-independent Gaussian noise into signal-dependent quantum noise.

  5. [Budget impact analysis of efavirenz daily dose reduction at the Verona University Hospital].

    PubMed

    Costa, Enrico; Biasi, Valeria; Concia, Ercole; Jommi, Claudio; Lattuada, Emanuela; Manfre, Silvia; Venturini, Francesca; Lanzafame, Massimiliano

    2014-06-01

    Efavirenz is a non-nucleoside-reverse-transcriptase-inhibitor used as part of highly-active-antiretroviral-therapy for the treatment of the human immunodeficiency virus (HIV) type 1 infection. The present paper aims to describing the impact of efavirenz dose reduction on the pharmaceutical budget at the Verona University Hospital. A budget impact analysis comparing two prescribing scenarios was conducted: all patients treated with the efavirenz full dose (600 mg per day) vs. a proportion of patients treated with a reduced dose (200-400 mg per day). All outpatients referring to the Infectious Disease Clinic in the period November 2009-October 2011 were selected. Out of 132 patients treated with efavirenz, 25 were not considered, mainly due to a too short treatment period. Of the remaining 107 patients, 68 received the full dose, while 39 received a reduced dosage. The analysis included the cost of the drug and of diagnostic tests, from the National Health Service perspective. The daily dose reduction of efavirenz saved 54,664 euros (a 30% expenditure reduction). In sum, new strategies for pharmaceutical system sustainability are necessary; despite forthcoming expiring patents of several drugs, spending on antiretroviral drugs is expected to rise. This paper suggests a way of linking clinical benefits and cost reduction.

  6. X-ray dose reduction by adaptive source equalization and electronic region-of-interest control

    NASA Astrophysics Data System (ADS)

    Burion, Steve; Sandman, Anne; Bechtel, Kate; Solomon, Edward; Funk, Tobias

    2011-03-01

    Radiation dose is particularly a concern in pediatric cardiac fluoroscopy procedures, which account for 7% of all cardiac procedures performed. The Scanning-Beam Digital X-ray (SBDX) fluoroscopy system has already demonstrated reduced dose in adult patients owing to its high-DQE photon-counting detector, reduced detected scatter, and the elimination of the anti-scatter grid. Here we show that the unique flexible illumination platform of the SBDX system will enable further dose area product reduction, which we are currently developing for pediatric patients, but which will ultimately benefit all patients. The SBDX system has a small-area detector array and a large-area X-ray source with up to 9,000 individually-controlled X-ray focal spots. Each focal spot illuminates a small fraction of the full field of view. To acquire a frame, each focal spot is activated for a fixed number of 1-microsecond periods. Dose reduction is made possible by reducing the number of activations of some of the X-ray focal spots during each frame time. This can be done dynamically to reduce the exposure in areas of low patient attenuation, such as the lung field. This spatially-adaptive illumination also reduces the dynamic range in the full image, which is visually pleasing. Dose can also be reduced by the user selecting a region of interest (ROI) where full image quality is to be maintained. Outside the ROI, the number of activations of each X-ray focal spot is reduced and the image gain is correspondingly increased to maintain consistent image brightness. Dose reduction is dependent on the size of the ROI and the desired image quality outside the ROI. We have developed simulation software that is based on real data and can simulate the performance of the equalization and ROI filtration. This software represents a first step toward real-time implementation of these dose-reduction methods. Our simulations have shown that dose area product reductions of 40% are possible using equalization

  7. Patient-specific dose estimation for pediatric chest CT

    SciTech Connect

    Li Xiang; Samei, Ehsan; Segars, W. Paul; Sturgeon, Gregory M.; Colsher, James G.; Frush, Donald P.

    2008-12-15

    any other patient in the same size/protocol group who undergoes the chest scan. In summary, this work reported the first assessment of dose variations across pediatric CT patients in the same size/protocol group due to the variability of patient anatomy and body habitus and provided a previously unavailable method for patient-specific organ dose estimation, which will help in assessing patient risk and optimizing dose reduction strategies, including the development of scan protocols.

  8. Dose reduction in CT using bismuth shielding: measurements and Monte Carlo simulations.

    PubMed

    Chang, Kyung-Hwan; Lee, Wonho; Choo, Dong-Myung; Lee, Choon-Sik; Kim, Youhyun

    2010-03-01

    In this research, using direct measurements and Monte Carlo calculations, the potential dose reduction achieved by bismuth shielding in computed tomography was evaluated. The patient dose was measured using an ionisation chamber in a polymethylmethacrylate (PMMA) phantom that had five measurement points at the centre and periphery. Simulations were performed using the MCNPX code. For both the bare and the bismuth-shielded phantom, the differences of dose values between experiment and simulation were within 9%. The dose reductions due to the bismuth shielding were 1.2-55% depending on the measurement points, X-ray tube voltage and the type of shielding. The amount of dose reduction was significant for the positions covered by the bismuth shielding (34 - 46% for head and 41 - 55% for body phantom on average) and negligible for other peripheral positions. The artefact on the reconstructed images were minimal when the distance between the shielding and the organs was >1 cm, and hence the shielding should be selectively located to protect critical organs such as the eye lens, thyroid and breast. The simulation results using the PMMA phantom was compared with those using a realistically voxelised phantom (KTMAN-2). For eye and breast, the simulation results using the PMMA and KTMAN-2 phantoms were similar with each other, while for thyroid the simulation results were different due to the discrepancy of locations and the sizes of the phantoms. The dose reductions achieved by bismuth and lead shielding were compared with each other and the results showed that the difference of the dose reductions achieved by the two materials was less than 2-3%.

  9. Dose reduction in CT using bismuth shielding: measurements and Monte Carlo simulations

    PubMed Central

    Chang, Kyung-Hwan; Lee, Wonho; Choo, Dong-Myung; Lee, Choon-Sik; Kim, Youhyun

    2010-01-01

    In this research, using direct measurements and Monte Carlo calculations, the potential dose reduction achieved by bismuth shielding in computed tomography was evaluated. The patient dose was measured using an ionisation chamber in a polymethylmethacrylate (PMMA) phantom that had five measurement points at the centre and periphery. Simulations were performed using the MCNPX code. For both the bare and the bismuth-shielded phantom, the differences of dose values between experiment and simulation were within 9 %. The dose reductions due to the bismuth shielding were 1.2–55 % depending on the measurement points, X-ray tube voltage and the type of shielding. The amount of dose reduction was significant for the positions covered by the bismuth shielding (34 − 46 % for head and 41 − 55 % for body phantom on average) and negligible for other peripheral positions. The artefact on the reconstructed images were minimal when the distance between the shielding and the organs was >1 cm, and hence the shielding should be selectively located to protect critical organs such as the eye lens, thyroid and breast. The simulation results using the PMMA phantom was compared with those using a realistically voxelised phantom (KTMAN-2). For eye and breast, the simulation results using the PMMA and KTMAN-2 phantoms were similar with each other, while for thyroid the simulation results were different due to the discrepancy of locations and the sizes of the phantoms. The dose reductions achieved by bismuth and lead shielding were compared with each other and the results showed that the difference of the dose reductions achieved by the two materials was less than 2–3 %. PMID:19959602

  10. Patient-specific dose calculation methods for high-dose-rate iridium-192 brachytherapy

    NASA Astrophysics Data System (ADS)

    Poon, Emily S.

    In high-dose-rate 192Ir brachytherapy, the radiation dose received by the patient is calculated according to the AAPM Task Group 43 (TG-43) formalism. This table-based dose superposition method uses dosimetry parameters derived with the radioactive 192Ir source centered in a water phantom. It neglects the dose perturbations caused by inhomogeneities, such as the patient anatomy, applicators, shielding, and radiographic contrast solution. In this work, we evaluated the dosimetric characteristics of a shielded rectal applicator with an endocavitary balloon injected with contrast solution. The dose distributions around this applicator were calculated by the GEANT4 Monte Carlo (MC) code and measured by ionization chamber and GAFCHROMIC EBT film. A patient-specific dose calculation study was then carried out for 40 rectal treatment plans. The PTRAN_CT MC code was used to calculate the dose based on computed tomography (CT) images. This study involved the development of BrachyGUI, an integrated treatment planning tool that can process DICOM-RT data and create PTRAN_CT input initialization files. BrachyGUI also comes with dose calculation and evaluation capabilities. We proposed a novel scatter correction method to account for the reduction in backscatter radiation near tissue-air interfaces. The first step requires calculating the doses contributed by primary and scattered photons separately, assuming a full scatter environment. The scatter dose in the patient is subsequently adjusted using a factor derived by MC calculations, which depends on the distances between the point of interest, the 192Ir source, and the body contour. The method was validated for multicatheter breast brachytherapy, in which the target and skin doses for 18 patient plans agreed with PTRAN_CT calculations better than 1%. Finally, we developed a CT-based analytical dose calculation method. It corrects for the photon attenuation and scatter based upon the radiological paths determined by ray tracing

  11. Dose reduction with iterative reconstruction for coronary CT angiography: a systematic review and meta-analysis

    PubMed Central

    Willemink, Martin J; De Ruiter, Quirina M B; De Jong, Pim A; Schilham, Arnold M R; Krestin, Gabriel P; Leiner, Tim; Budde, Ricardo P J

    2016-01-01

    Objective: To investigate the achievable radiation dose reduction for coronary CT angiography (CCTA) with iterative reconstruction (IR) in adults and the effects on image quality. Methods: PubMed and EMBASE were searched, and original articles concerning IR for CCTA in adults using prospective electrocardiogram triggering were included. Primary outcome was the effective dose using filtered back projection (FBP) and IR. Secondary outcome was the effect of IR on objective and subjective image quality. Results: The search yielded 1616 unique articles, of which 10 studies (1042 patients) were included. The pooled routine effective dose with FBP was 4.2 mSv [95% confidence interval (CI) 3.5–5.0]. A dose reduction of 48% to a pooled effective dose of 2.2 mSv (95% CI 1.3–3.1) using IR was reported. Noise, contrast-to-noise ratio and subjective image quality were equal or improved in all but one study, whereas signal-to-noise ratio was decreased in two studies with IR at reduced dose. Conclusion: IR allows for CCTA acquisition with an effective dose of 2.2 mSv with preserved objective and subjective image quality. PMID:26562096

  12. On the Need to Compensate for Edema-Induced Dose Reductions in Preplanned {sup 131}Cs Prostate Brachytherapy

    SciTech Connect

    Chen, Z. Jay Deng Jun; Roberts, Kenneth; Nath, Ravinder

    2008-01-01

    Purpose: Surgical trauma-induced edema and its protracted resolution can lead to significant dose reductions in preplanned {sup 131}Cs prostate brachytherapy. The purpose of this work was to examine whether these dose reductions should be actively compensated for and to estimate the magnitude of the additional irradiation needed for dose compensation. Methods and Materials: The quantitative edema resolution characteristics observed by Waterman et al. were used to examine the physical and radiobiologic effects of prostate edema in preplanned {sup 131}Cs implants. The need for dose compensation was assessed using the dose responses observed in {sup 125}I and {sup 103}Pd prostate implants. The biologically effective dose, calculated with full consideration of edema evolution, was used to estimate the additional irradiation needed for dose compensation. Results: We found that the edema-induced dose reduction in preplanned {sup 131}Cs implants could easily exceed 10% of the prescription dose for implants with moderate or large edema. These dose reductions could lead to a >10% reduction in the biochemical recurrence-free survival for individual patients if the effect of edema was ignored. For a prescribed dose of 120 Gy, the number of 2-Gy external beam fractions needed to compensate for a 5%, 10%, 15%, 20%, and 25% edema-induced dose reduction would be one, four, six, seven, and nine, respectively, for prostate cancer with a median potential doubling time of 42 days. The required additional irradiation increased for fast-growing tumors and/or those less efficient in sublethal damage repair. Conclusion: Compensation of edema-induced dose reductions in preplanned {sup 131}Cs prostate brachytherapy should be actively considered for those implants with moderate or large edema.

  13. Potential of combining iterative reconstruction with noise efficient detector design: aggressive dose reduction in head CT

    PubMed Central

    Bender, B; Schabel, C; Fenchel, M; Ernemann, U; Korn, A

    2015-01-01

    Objective: With further increase of CT numbers and their dominant contribution to medical exposure, there is a recent quest for more effective dose control. While reintroduction of iterative reconstruction (IR) has proved its potential in many applications, a novel focus is placed on more noise efficient detectors. Our purpose was to assess the potential of IR in combination with an integrated circuit detector (ICD) for aggressive dose reduction in head CT. Methods: Non-contrast low-dose head CT [190 mAs; weighted volume CT dose index (CTDIvol), 33.2 mGy] was performed in 50 consecutive patients, using a new noise efficient detector and IR. Images were assessed in terms of quantitative and qualitative image quality and compared with standard dose acquisitions (320 mAs; CTDIvol, 59.7 mGy) using a conventional detector and filtered back projection. Results: By combining ICD and IR in low-dose examinations, the signal to noise was improved by about 13% above the baseline level in the standard-dose control group. Both, contrast-to-noise ratio (2.02 ± 0.6 vs 1.88 ± 0.4; p = 0.18) and objective measurements of image sharpness (695 ± 84 vs 705 ± 151 change in Hounsfield units per pixel; p = 0.79) were fully preserved in the low-dose group. Likewise, there was no significant difference in the grading of several subjective image quality parameters when both noise-reducing strategies were used in low-dose examinations. Conclusion: Combination of noise efficient detector with IR allows for meaningful dose reduction in head CT without compromise of standard image quality. Advances in knowledge: Our study demonstrates the feasibility of almost 50% dose reduction in head CT dose (1.1 mSv per scan) through combination of novel dose-reducing strategies. PMID:25827204

  14. Kilovoltage Imaging Doses in the Radiotherapy of Pediatric Cancer Patients

    SciTech Connect

    Deng Jun; Chen Zhe; Roberts, Kenneth B.; Nath, Ravinder

    2012-04-01

    Purpose: To investigate doses induced by kilovoltage cone-beam computed tomography (kVCBCT) to pediatric cancer patients undergoing radiotherapy, as well as strategies for dose reduction. Methods and Materials: An EGS4 Monte Carlo code was used to calculate three-dimensional dose deposition due to kVCBCT on 4 pediatric cancer patients. Absorbed doses to various organs were analyzed for both half-fan and full-fan modes. Clinical conditions, such as distance from organ at risk (OAR) to CBCT field border, kV peak energy, and testicular shielding, were studied. Results: The mean doses induced by one CBCT scan operated at 125 kV in half-fan mode to testes, liver, kidneys, femoral heads, spinal cord, brain, eyes, lens, and optical nerves were 2.9, 4.7, 7.7, 10.5, 8.8, 7.6, 7.7, 7.8, and 7.2 cGy, respectively. Increasing the distances from OARs to CBCT field border greatly reduced the doses to OARs, ranging from 33% reduction for spinal cord to 2300% reduction for testes. As photon beam energy increased from 60 to 125 kV, the dose increase due to kVCBCT ranged from 170% for lens to 460% for brain and spinal cord. A testicular shielding made of 1-cm cerrobend could reduce CBCT doses down to 31%, 51%, 68%, and 82%, respectively, for 60, 80, 100, and 125 kV when the testes lay within the CBCT field. Conclusions: Generally speaking, kVCBCT deposits much larger doses to critical structures in children than in adults, usually by a factor of 2 to 3. Increasing the distances from OARs to CBCT field border greatly reduces doses to OARs. Depending on OARs, kVCBCT-induced doses increase linearly or exponentially with photon beam energy. Testicular shielding works more efficiently at lower kV energies. On the basis of our study, it is essential to choose an appropriate scanning protocol when kVCBCT is applied to pediatric cancer patients routinely.

  15. Iterative methods for dose reduction and image enhancement in tomography

    DOEpatents

    Miao, Jianwei; Fahimian, Benjamin Pooya

    2012-09-18

    A system and method for creating a three dimensional cross sectional image of an object by the reconstruction of its projections that have been iteratively refined through modification in object space and Fourier space is disclosed. The invention provides systems and methods for use with any tomographic imaging system that reconstructs an object from its projections. In one embodiment, the invention presents a method to eliminate interpolations present in conventional tomography. The method has been experimentally shown to provide higher resolution and improved image quality parameters over existing approaches. A primary benefit of the method is radiation dose reduction since the invention can produce an image of a desired quality with a fewer number projections than seen with conventional methods.

  16. Patient dose levels for seven different radiographic examination types.

    PubMed

    Abdelhalim, Mohamed Anwar K

    2010-04-01

    This study was carried out as a part of a comprehensive project to establish a national diagnostic reference level (NDRL), for the first time, in Saudi Arabia. Seven of the most common X-ray examinations (10 projections) were included. This study consisted of 200 patients who were referred for X-ray examinations at King Khalid University Hospital (KKUH). The selected X-ray examinations were skull (PA), kub (AP and LAT), ankle (AP and LAT), foot (AP/OBL and LAT/OBL), hib (AP and LAT) and sinuses paranasal (AP). Mean patient information and exposure parameters for these seven radiographic examinations were recorded at KKUH. Some of these radiographic examinations were compared with their corresponding values at other national places [Security Forces Hospital (SFH); King Abdulaziz City for Science and Technology (KACST)] in Saudi Arabia. We found that the patient mean dose values recorded at KKUH were varied from those recorded at other national places. Wide variations in patient dose arising from a specific type of X-ray examination at different national places suggests that significant reductions in patient dose would be possible without affecting image quality. Furthermore, variations in patient dose may emerge from the examination technique, clinical condition, radiologist skill, tube current, tube potential and focus to film distance. The data of this study will be useful for the formulation of NDRLs, and it is also provides local diagnostic reference levels for some diagnostic X-ray examinations at KKUH and other national places in Saudi Arabia.

  17. Doses metrics and patient age in CT.

    PubMed

    Huda, Walter; Tipnis, Sameer V

    2016-03-01

    The aim of this study was to investigate how effective dose and size-specific dose estimate (SSDE) change with patient age (size) for routine head and abdominal/pelvic CT examinations. Heads and abdomens of patients were modelled as a mass-equivalent cylinder of water corresponding to the patient 'effective diameter'. Head CT scans were performed at CTDIvol(S) of 40 mGy, and abdominal CT scans were performed at CTDIvol(L) of 10 mGy. Values of SSDE were obtained using conversion factors in AAPM Task Group Report 204. Age-specific scan lengths for head and abdominal CT scans obtained from the authors' clinical practice were used to estimate the dose-length product for each CT examination. Effective doses were calculated from previously published age- and sex-specific E/DLP conversion factors, based on ICRP 103 organ-weighting factors. For head CT examinations, the scan length increased from 15 cm in a newborn to 20 cm in adults, and for an abdominal/pelvic CT, the scan length increased from 20 cm in a newborn to 45 cm in adults. For head CT scans, SSDE ranged from 37.2 mGy in adults to 48.8 mGy in a newborn, an increase of 31 %. The corresponding head CT effective doses range from 1.4 mSv in adults to 5.2 mSv in a newborn, an increase of 270 %. For abdomen CT scans, SSDE ranged from 13.7 mGy in adults to 23.0 mGy in a newborn, an increase of 68 %. The corresponding abdominal CT effective doses ranged from 6.3 mSv in adults to 15.4 mSv in a newborn, an increase of 140 %. SSDE increases much less than effective dose in paediatric patients compared with adults because it does not account for scan length or scattered radiation. Size- and age-specific effective doses better quantify the total radiation received by patients in CT by explicitly accounting for all organ doses, as well as their relative radio sensitivity.

  18. Dose reduction in LDR brachytherapy by implanted prostate gold fiducial markers

    SciTech Connect

    Landry, Guillaume; Reniers, Brigitte; Lutgens, Ludy; Murrer, Lars; Afsharpour, Hossein; Haas-Kock, Danielle de; Visser, Peter; Gils, Francis van; Verhaegen, Frank

    2012-03-15

    Purpose: The dosimetric impact of gold fiducial markers (FM) implanted prior to external beam radiotherapy of prostate cancer on low dose rate (LDR) brachytherapy seed implants performed in the context of combined therapy was investigated. Methods: A virtual water phantom was designed containing a single FM. Single and multi source scenarios were investigated by performing Monte Carlo dose calculations, along with the influence of varying orientation and distance of the FM with respect to the sources. Three prostate cancer patients treated with LDR brachytherapy for a recurrence following external beam radiotherapy with implanted FM were studied as surrogate cases to combined therapy. FM and brachytherapy seeds were identified on post implant CT scans and Monte Carlo dose calculations were performed with and without FM. The dosimetric impact of the FM was evaluated by quantifying the amplitude of dose shadows and the volume of cold spots. D{sub 90} was reported based on the post implant CT prostate contour. Results: Large shadows are observed in the single source-FM scenarios. As expected from geometric considerations, the shadows are dependent on source-FM distance and orientation. Large dose reductions are observed at the distal side of FM, while at the proximal side a dose enhancement is observed. In multisource scenarios, the importance of shadows appears mitigated, although FM at the periphery of the seed distribution caused underdosage (dose). In clinical cases, the FM reduced the dose to some voxels by up to 50% and generated shadows with extents of the order of 4 mm. Within the prostate contour, cold spots (<95% prescription dose) of the order of 20 mm{sup 3} were observed. D{sub 90} proved insensitive to the presence of FM for the cases selected. Conclusions: There is a major local impact of FM present in LDR brachytherapy seed implant dose distributions. Therefore, reduced tumor control could be expected from FM implanted in tumors, although

  19. Optimizing CT radiation dose based on patient size and image quality: the size-specific dose estimate method.

    PubMed

    Larson, David B

    2014-10-01

    The principle of ALARA (dose as low as reasonably achievable) calls for dose optimization rather than dose reduction, per se. Optimization of CT radiation dose is accomplished by producing images of acceptable diagnostic image quality using the lowest dose method available. Because it is image quality that constrains the dose, CT dose optimization is primarily a problem of image quality rather than radiation dose. Therefore, the primary focus in CT radiation dose optimization should be on image quality. However, no reliable direct measure of image quality has been developed for routine clinical practice. Until such measures become available, size-specific dose estimates (SSDE) can be used as a reasonable image-quality estimate. The SSDE method of radiation dose optimization for CT abdomen and pelvis consists of plotting SSDE for a sample of examinations as a function of patient size, establishing an SSDE threshold curve based on radiologists' assessment of image quality, and modifying protocols to consistently produce doses that are slightly above the threshold SSDE curve. Challenges in operationalizing CT radiation dose optimization include data gathering and monitoring, managing the complexities of the numerous protocols, scanners and operators, and understanding the relationship of the automated tube current modulation (ATCM) parameters to image quality. Because CT manufacturers currently maintain their ATCM algorithms as secret for proprietary reasons, prospective modeling of SSDE for patient populations is not possible without reverse engineering the ATCM algorithm and, hence, optimization by this method requires a trial-and-error approach.

  20. [Phantom Study on Dose Reduction Using Iterative Reconstruction in Low-dose Computed Tomography for Lung Cancer Screening].

    PubMed

    Minehiro, Kaori; Takata, Tadanori; Hayashi, Hiroyuki; Sakuda, Keita; Nunome, Haruka; Kawashima, Hiroko; Sanada, Shigeru

    2015-12-01

    We investigated dose reduction ability of an iterative reconstruction technology for low-dose computed tomography (CT) for lung cancer screening. The Sinogram Affirmed Iterative Reconstruction (SAFIRE) provided in a multi slice CT system, Somatom Definition Flash (Siemens Healthcare) was used. An anthropomorphic chest phantom (N-1, Kyoto Kagaku) was scanned at volume CT dose index (CTDIvol) of 0.50-11.86 mGy with 120 kV. For noise (standard deviation) and contrast-to-noise ratio (CNR) measurements, CTP486 and CTP515 modules in the Catphan (The Phantom Laboratory) were scanned. Radiological technologists were participated in the perceptual comparison. SAFIRE reduced the SD values by approximately 50% compared with filter back projection (FBP). The estimated dose reduction rates by SAFIRE determined from the perceptual comparison was approximately 23%, while 75% dose reduction rate was expected from the SD value reduction of 50%.

  1. Patient doses from CT examinations in Turkey

    PubMed Central

    Ataç, Gökçe Kaan; Parmaksız, Aydın; İnal, Tolga; Bulur, Emine; Bulgurlu, Figen; Öncü, Tolga; Gündoğdu, Sadi

    2015-01-01

    PURPOSE We aimed to establish the first diagnostic reference levels (DRLs) for computed tomography (CT) examinations in adult and pediatric patients in Turkey and compare these with international DRLs. METHODS CT performance information and examination parameters (for head, chest, high-resolution CT of the chest [HRCT-chest], abdominal, and pelvic protocols) from 1607 hospitals were collected via a survey. Dose length products and effective doses for standard patient sizes were calculated from the reported volume CT dose index (CTDIvol). RESULTS The median number of protocols reported from the 167 responding hospitals (10% response rate) was 102 across five different age groups. Third quartile CTDIvol values for adult pelvic and all pediatric body protocols were higher than the European Commission standards but were comparable to studies conducted in other countries. CONCLUSION The radiation dose indicators for adult patients were similar to those reported in the literature, except for those associated with head protocols. CT protocol optimization is necessary for adult head and pediatric chest, HRCT-chest, abdominal, and pelvic protocols. The findings from this study are recommended for use as national DRLs in Turkey. PMID:26133189

  2. Automatic selection of tube potential for radiation dose reduction in CT: A general strategy

    SciTech Connect

    Yu Lifeng; Li Hua; Fletcher, Joel G.; McCollough, Cynthia H.

    2010-01-15

    Purpose: To optimize radiation dose efficiency in CT while maintaining image quality, it is important to select the optimal tube potential. The selection of optimal tube potential, however, is highly dependent on patient size and diagnostic task. The purpose of this work was to develop a general strategy that allows for automatic tube potential selection for each individual patient and each diagnostic task. Methods: The authors propose a general strategy that allows automatic adaptation of the tube potential as a function of patient size and diagnostic task, using a novel index of image quality, ''iodine contrast to noise ratio with a noise constraint (iCNR{sub N}C),'' to characterize the different image quality requirements by various clinical applications. The relative dose factor (RDF) at each tube potential to achieve a target image quality was then determined as a function of patient size and the noise constraint parameter. A workflow was developed to automatically identify the optimal tube potential that is both dose efficient and practically feasible, incorporating patient size and diagnostic task. An experimental study using a series of semianthropomorphic thoracic phantoms was used to demonstrate how the proposed general strategy can be implemented and how the radiation dose reduction achievable by the tube potential selection depends on phantom sizes and noise constraint parameters. Results: The proposed strategy provides a flexible and quantitative way to select the optimal tube potential based on the patient size and diagnostic task. The noise constraint parameter {alpha} can be adapted for different clinical applications. For example, {alpha}=1 for noncontrast routine exams; {alpha}=1.1-1.25 for contrast-enhanced routine exams; and {alpha}=1.5-2.0 for CT angiography. For the five thoracic phantoms in the experiment, when {alpha}=1, the optimal tube potentials were 80, 100, 100, 120, 120, respectively. The corresponding RDFs (relative to 120 kV) were 78

  3. CT Radiation Dose Management: A Comprehensive Optimization Process for Improving Patient Safety.

    PubMed

    Parakh, Anushri; Kortesniemi, Mika; Schindera, Sebastian T

    2016-09-01

    Rising concerns of radiation exposure from computed tomography have caused various advances in dose reduction technologies. While proper justification and optimization of scans has been the main focus to address increasing doses, the value of dose management has been largely overlooked. The purpose of this article is to explain the importance of dose management, provide an overview of the available options for dose tracking, and discuss the importance of a dedicated dose team. The authors also describe how a digital radiation tracking software can be used for analyzing the big data on doses for auditing patient safety, scanner utilization, and productivity, all of which have enormous personal and institutional implications. (©) RSNA, 2016.

  4. Intrathyroidal iodide binding rates and plasma methimazole concentrations in hyperthyroid patients on small doses of carbimazole.

    PubMed Central

    Low, L C; McCruden, D C; Alexander, W D; Hilditch, T E; Skellern, G G; Knight, B I

    1981-01-01

    1 The effect of small doses of carbimazole on the binding rate constant of intrathyroidal iodide, plasma methimazole concentrations and circulating thyroid hormone concentrations in five hyperthyroid patients is presented. 2 In all patients there was a marked reduction in iodide binding with carbimazole doses as low as 5 to 10 mg daily. 3 In three patients little further reduction in the observed binding rate occurred with daily doses in excess of 10 mg despite progressive increases in plasma methimazole concentrations. 4 At the end of 4 weeks' treatment with 10 mg carbimazole daily, the reduction in thyroid hormone concentrations and clinical improvement were such as to suggest that this dose may be an effective starting dose in many patients. PMID:7295461

  5. A radiobiological model of metastatic burden reduction for molecular radiotherapy: application to patients with bone metastases

    NASA Astrophysics Data System (ADS)

    Denis-Bacelar, Ana M.; Chittenden, Sarah J.; Murray, Iain; Divoli, Antigoni; McCready, V. Ralph; Dearnaley, David P.; O’Sullivan, Joe M.; Johnson, Bernadette; Flux, Glenn D.

    2017-04-01

    Skeletal tumour burden is a biomarker of prognosis and survival in cancer patients. This study proposes a novel method based on the linear quadratic model to predict the reduction in metastatic tumour burden as a function of the absorbed doses delivered from molecular radiotherapy treatments. The range of absorbed doses necessary to eradicate all the bone lesions and to reduce the metastatic burden was investigated in a cohort of 22 patients with bone metastases from castration-resistant prostate cancer. A metastatic burden reduction curve was generated for each patient, which predicts the reduction in metastatic burden as a function of the patient mean absorbed dose, defined as the mean of all the lesion absorbed doses in any given patient. In the patient cohort studied, the median of the patient mean absorbed dose predicted to reduce the metastatic burden by 50% was 89 Gy (interquartile range: 83–105 Gy), whilst a median of 183 Gy (interquartile range: 107–247 Gy) was found necessary to eradicate all metastases in a given patient. The absorbed dose required to eradicate all the lesions was strongly correlated with the variability of the absorbed doses delivered to multiple lesions in a given patient (r  =  0.98, P  <  0.0001). The metastatic burden reduction curves showed a potential large reduction in metastatic burden for a small increase in absorbed dose in 91% of patients. The results indicate the range of absorbed doses required to potentially obtain a significant survival benefit. The metastatic burden reduction method provides a simple tool that could be used in routine clinical practice for patient selection and to indicate the required administered activity to achieve a predicted patient mean absorbed dose and reduction in metastatic tumour burden.

  6. A radiobiological model of metastatic burden reduction for molecular radiotherapy: application to patients with bone metastases.

    PubMed

    Denis-Bacelar, Ana M; Chittenden, Sarah J; Murray, Iain; Divoli, Antigoni; Ralph McCready, V; Dearnaley, David P; O'Sullivan, Joe M; Johnson, Bernadette; Flux, Glenn D

    2017-04-07

    Skeletal tumour burden is a biomarker of prognosis and survival in cancer patients. This study proposes a novel method based on the linear quadratic model to predict the reduction in metastatic tumour burden as a function of the absorbed doses delivered from molecular radiotherapy treatments. The range of absorbed doses necessary to eradicate all the bone lesions and to reduce the metastatic burden was investigated in a cohort of 22 patients with bone metastases from castration-resistant prostate cancer. A metastatic burden reduction curve was generated for each patient, which predicts the reduction in metastatic burden as a function of the patient mean absorbed dose, defined as the mean of all the lesion absorbed doses in any given patient. In the patient cohort studied, the median of the patient mean absorbed dose predicted to reduce the metastatic burden by 50% was 89 Gy (interquartile range: 83-105 Gy), whilst a median of 183 Gy (interquartile range: 107-247 Gy) was found necessary to eradicate all metastases in a given patient. The absorbed dose required to eradicate all the lesions was strongly correlated with the variability of the absorbed doses delivered to multiple lesions in a given patient (r  =  0.98, P  <  0.0001). The metastatic burden reduction curves showed a potential large reduction in metastatic burden for a small increase in absorbed dose in 91% of patients. The results indicate the range of absorbed doses required to potentially obtain a significant survival benefit. The metastatic burden reduction method provides a simple tool that could be used in routine clinical practice for patient selection and to indicate the required administered activity to achieve a predicted patient mean absorbed dose and reduction in metastatic tumour burden.

  7. Characteristics of Movement-Induced Dose Reduction in Target Volume: A Comparison Between Photon and Proton Beam Treatment

    SciTech Connect

    Yoon, Myonggeun; Shin, Dongho; Kwak, Jungwon; Park, Soah; Lim, Young Kyung; Kim, Dongwook; Park, Sung Yong Lee, Se Byeong; Shin, Kyung Hwan; Kim, Tae Hyun; Cho, Kwan Ho

    2009-10-01

    We compared the main characteristics of movement-induced dose reduction during photon and proton beam treatment, based on an analysis of dose-volume histograms. To simulate target movement, a target contour was delineated in a scanned phantom and displaced by 3 to 20 mm. Although the dose reductions to the target in the 2 treatment systems were similar for transverse (perpendicular to beam direction) target motion, they were completely different for longitudinal (parallel to beam direction) target motion. While both modalities showed a relationship between the degree of target shift and the reduction in dose coverage, dose reduction showed a strong directional dependence in proton beam treatment. Clinical simulation of target movement for a prostate cancer patient showed that, although coverage and conformity indices for a 6-mm lateral movement of the prostate were reduced by 9% and 16%, respectively, for proton beam treatment, they were reduced by only 1% and 7%, respectively, for photon treatment. This difference was greater for a 15-mm target movement in the lateral direction, which lowered the coverage and conformity indices by 34% and 54%, respectively, for proton beam treatment, but changed little during photon treatment. In addition, we found that the equivalent uniform dose (EUD) and homogeneity index show similar characteristics during target movement. These results suggest that movement-induced dose reduction differs significantly between photon and proton beam treatment. Attention should be paid to the target margin in proton beam treatment due to the distinct characteristics of heavy ion beams.

  8. Escalation to High-Dose Defibrotide in Patients with Hepatic Veno-Occlusive Disease.

    PubMed

    Triplett, Brandon M; Kuttab, Hani I; Kang, Guolian; Leung, Wing

    2015-12-01

    Hepatic veno-occlusive disease (VOD) is a serious complication of high-dose chemotherapy regimens, such as those used in hematopoietic cell transplantation recipients. Defibrotide is considered a safe and effective treatment when dosed at 25 mg/kg/day. However, patients who develop VOD still have increased mortality despite the use of defibrotide. Data are limited on the use of doses above 60 mg/kg/day for persistent VOD. In this prospective clinical trial 34 patients received escalating doses of defibrotide. For patients with persistent VOD despite doses of 60 mg/kg/day, doses were increased to a maximum of 110 mg/kg/day. Increased toxicity was not observed until doses rose beyond 100 mg/kg/day. Patients receiving doses between 10 and 100 mg/kg/day experienced an average of 3 bleeding episodes per 100 days of treatment, whereas those receiving doses >100 mg/kg/day experienced 13.2 bleeding episodes per 100 days (P = .008). Moreover, dose reductions due to toxicity were needed at doses of 110 mg/kg/day more often than at lower doses. Defibrotide may be safely escalated to doses well above the current standard without an increase in bleeding risk. However, the efficacy of this dose-escalation strategy remains unclear, because outcomes were similar to published cohorts of patients receiving standard doses of defibrotide for VOD.

  9. Antibiotic dose optimization in critically ill patients.

    PubMed

    Cotta, M O; Roberts, J A; Lipman, J

    2015-12-01

    The judicious use of existing antibiotics is essential for preserving their activity against infections. In the era of multi-drug resistance, this is of particular importance in clinical areas characterized by high antibiotic use, such as the ICU. Antibiotic dose optimization in critically ill patients requires sound knowledge not only of the altered physiology in serious infections - including severe sepsis, septic shock and ventilator-associated pneumonia - but also of the pathogen-drug exposure relationship (i.e. pharmacokinetic/pharmacodynamic index). An important consideration is the fact that extreme shifts in organ function, such as those seen in hyperdynamic patients or those with multiple organ dysfunction syndrome, can have an impact upon drug exposure, and constant vigilance is required when reviewing antibiotic dosing regimens in the critically ill. The use of continuous renal replacement therapy and extracorporeal membrane oxygenation remain important interventions in these patients; however, both of these treatments can have a profound effect on antibiotic exposure. We suggest placing emphasis on the use of therapeutic drug monitoring and dose individualization when optimizing therapy in these settings.

  10. [Dialysis dose quantification in critically ill patients].

    PubMed

    Casino, Francesco Gaetano

    2010-01-01

    Acute kidney injury affects about 35% of intensive care unit patients. Renal replacement therapy is required in about 5% of such patients and is associated with a mortality rate as high as 50% to 80%. The latter is likely more related to the failure of extrarenal organs than to an insufficient dialysis dose. This could explain, at least in part, the findings of 2 recent trials (VA/ NIH and RENAL) where the expected dose-outcome relationship was not confirmed. These results cannot be taken to infer that assessing the dialysis dose is no longer required. The contrary is true, in that the common finding of large differences between prescribed and delivered doses calls for accurate dose assessment, at least to avoid underdialysis. The minimum adequate levels are now a Kt/V urea of 1.2 to 1.4 three times a week (3x/wk) on intermittent hemodialysis (IHD), and an effluent of 20 mL/kg/h for 85% of the time on continuous renal replacement therapy (CRTT). Both these parameters can be easily measured but are far from ideal indices because they account neither for residual renal function nor for irregular dose delivery. The equivalent renal urea clearance (EKRjc), by expressing the averaged renal+dialytic urea clearance over the whole treatment period, is able to account for the above factors. Although assessing EKRjc is quite complex, for regular 3x/wk IHD one could use the formula EKRjc=10 Kt/V+1 to compute that a Kt/V of 1.2 and 1.4 corresponds to an EKRjc of 13 and 15 mL/min, respectively. On the other hand, the hourly effluent per kg is numerically similar to EKRjc. On this basis it can be calculated that in non-prediluted really continuous treatment, the recommended CRRT dose (EKRjc=20 mL/min) is 33% higher than the EKRjc of 15 mL/min, corresponding to the recommended Kt/V of 1.4 on 3x/wk IHD.

  11. Measurement of dose reductions for superficial x-rays backscattered from bone interfaces.

    PubMed

    Butson, Martin J; Cheung, Tsang; Yu, Peter K N

    2008-09-07

    Accurate measurement and knowledge of dose delivered during superficial x-ray radiotherapy is required for patient dose assessment. Some tumours treated near the surface (within the first few centimetres) can have large posterior bone structures. This can cause perturbations to dose delivered due to changed backscatter contributions from the bony structure as compared to full water or tissue scattering conditions. Measured results have shown that up to 7.5% of Dmax reductions in dose can occur near the water/bone interface for 100 kVp, using 10 cm diameter field sizes when a 1 cm thick slab of bone is located at 2 cm depth. At smaller field sizes such as 2 cm diameter these values reduce to 2% for the same energy. Larger variations (up to 12.5% of maximum) have been seen at the phantom surface when the bone layer is directly behind the point of interest (within 0.5 mm) and smaller effects (up to 5% of maximum) at depths down to 5 cm. Interesting to note is the fact that for larger field sizes, an increase in percentage dose is found at the water/bone interface due to the production of low energy backscattered electrons similar to the effect found in lead. However, they are much smaller in magnitude and thus would not cause any significant dosimetric effects. In the case where large bony structures lie relatively close to the surface and the tissue above this region is being treated, a dosimeter such as radiochromic film can be used to estimate the dose reduction that may occur due to the changed backscatter conditions.

  12. Radiation Dose Estimation for Pediatric Patients Undergoing Cardiac Catheterization

    NASA Astrophysics Data System (ADS)

    Wang, Chu

    correction factors for the MOSFET organ dose measurements in the following studies. Minor angular dependence (< +/-20% at all angles tested, < +/-10% at clinically relevant angles in cardiac catheterization) was observed. Second, the cardiac dose for common fluoroscopic imaging techniques for pediatric patients in the two age groups was measured. Imaging technique settings with variations of individual key imaging parameters were tested to observe the quantitative effect of imaging optimization or lack thereof. Along with each measurement, the two standard system output indices, the Air Kerma (AK) and Dose-Area Product (DAP), were also recorded and compared to the measured cardiac and skin doses -- the lack of correlation between the indices and the organ doses shed light to the substantial limitation of the indices in representing patient radiation dose, at least within the scope of this dissertation. Third, the effective dose (ED) for Posterior-Anterior and Lateral fluoroscopic imaging techniques for pediatric patients in the two age groups was determined. In addition, the dosimetric effect of removing the anti-scatter grid was studied, for which a factor-of-two ED rate reduction was observed for the imaging techniques. The Clinical Component involved analytical research to develop a validated retrospective cardiac dose reconstruction formulation and to propose the new Optimization Index which evaluates the level of optimization of the clinician's imaging usage during a procedure; and small sample group of actual procedures were used to demonstrate applicability of these formulations. In its entirety, the research represents a first-of-its-kind comprehensive approach in radiation dosimetry for pediatric cardiac catheterization; and separately, it is also modular enough that each individual section can serve as study templates for small-scale dosimetric studies of similar purposes. The data collected and algorithmic formulations developed can be of use in areas of

  13. Organ equivalent doses of patients undergoing chest computed tomography: measurements with TL dosimeters in an anthropomorphic phantom.

    PubMed

    Gonzaga, N B; Mourão, A P; Magalhães, M J; da Silva, T A

    2014-01-01

    Dose reduction in patients undergoing computed tomography (CT) examinations has become a concern in many countries. CT dosimetric quantities were defined aiming optimization of CT procedures, organ absorbed doses and effective doses have been calculated for radiation risk assessments in patients. In this work, an experimental methodology was established for measuring organ doses with thermoluminescent (TL) dosimeters in an anthropomorphic phantom for routine CT chest examinations. Results may be useful for validating computational software used for CT dose calculations.

  14. Dose reconstruction for real-time patient-specific dose estimation in CT

    SciTech Connect

    De Man, Bruno Yin, Zhye; Wu, Mingye; FitzGerald, Paul; Kalra, Mannudeep

    2015-05-15

    Purpose: Many recent computed tomography (CT) dose reduction approaches belong to one of three categories: statistical reconstruction algorithms, efficient x-ray detectors, and optimized CT acquisition schemes with precise control over the x-ray distribution. The latter category could greatly benefit from fast and accurate methods for dose estimation, which would enable real-time patient-specific protocol optimization. Methods: The authors present a new method for volumetrically reconstructing absorbed dose on a per-voxel basis, directly from the actual CT images. The authors’ specific implementation combines a distance-driven pencil-beam approach to model the first-order x-ray interactions with a set of Gaussian convolution kernels to model the higher-order x-ray interactions. The authors performed a number of 3D simulation experiments comparing the proposed method to a Monte Carlo based ground truth. Results: The authors’ results indicate that the proposed approach offers a good trade-off between accuracy and computational efficiency. The images show a good qualitative correspondence to Monte Carlo estimates. Preliminary quantitative results show errors below 10%, except in bone regions, where the authors see a bigger model mismatch. The computational complexity is similar to that of a low-resolution filtered-backprojection algorithm. Conclusions: The authors present a method for analytic dose reconstruction in CT, similar to the techniques used in radiation therapy planning with megavoltage energies. Future work will include refinements of the proposed method to improve the accuracy as well as a more extensive validation study. The proposed method is not intended to replace methods that track individual x-ray photons, but the authors expect that it may prove useful in applications where real-time patient-specific dose estimation is required.

  15. Reduction of absorbed doses in radiography of the facial skeleton

    SciTech Connect

    Julin, P.; Kraepelien, T.

    1984-11-01

    Radiation absorbed doses from radiography of the paranasal sinuses and the facial skeleton were measured with thermoluminescent dosimeters (TLD) on a phantom head using high-sensitivity screens in an Orbix stand. The entrance doses to the skin of the head ranged from 0.31 to 2.9 mGy per exposure. The absorbed dose from a full series of sinus exposures averaged 0.33 mGy for the oral mucous membrane, 0.33 mGy for the maxillary sinus mucous membrane, 0.11 MgY for the parotid gland, 0.15 MgY for the submandibular gland, 0.61 mGy for the eye lens, and 0.75 mGy for the thyroid gland region. A leaded soft collar adapted to the thyroid region reduced the thyroid doses by more than one order of magnitude, but also reduced the image field.

  16. Patient dose considerations in computed tomography examinations

    PubMed Central

    Tsalafoutas, Ioannis A; Koukourakis, Georgios V

    2010-01-01

    Ionizing radiation is extensively used in medicine and its contribution to both diagnosis and therapy is undisputable. However, the use of ionizing radiation also involves a certain risk since it may cause damage to tissues and organs and trigger carcinogenesis. Computed tomography (CT) is currently one of the major contributors to the collective population radiation dose both because it is a relatively high dose examination and an increasing number of people are subjected to CT examinations many times during their lifetime. The evolution of CT scanner technology has greatly increased the clinical applications of CT and its availability throughout the world and made it a routine rather than a specialized examination. With the modern multislice CT scanners, fast volume scanning of the whole human body within less than 1 min is now feasible. Two dimensional images of superb quality can be reconstructed in every possible plane with respect to the patient axis (e.g. axial, sagital and coronal). Furthermore, three-dimensional images of all anatomic structures and organs can be produced with only minimal additional effort (e.g. skeleton, tracheobronchial tree, gastrointestinal system and cardiovascular system). All these applications, which are diagnostically valuable, also involve a significant radiation risk. Therefore, all medical professionals involved with CT, either as referring or examining medical doctors must be aware of the risks involved before they decide to prescribe or perform CT examinations. Ultimately, the final decision concerning justification for a prescribed CT examination lies upon the radiologist. In this paper, we summarize the basic information concerning the detrimental effects of ionizing radiation, as well as the CT dosimetry background. Furthermore, after a brief summary of the evolution of CT scanning, the current CT scanner technology and its special features with respect to patient doses are given in detail. Some numerical data is also

  17. Does administering iodine in radiological procedures increase patient doses?

    SciTech Connect

    He, Wenjun; Yao, Hai; Huda, Walter; Mah, Eugene

    2014-11-01

    Purpose: The authors investigated the changes in the pattern of energy deposition in tissue equivalent phantoms following the introduction of iodinated contrast media. Methods: The phantom consisted of a small “contrast sphere,” filled with water or iodinated contrast, located at the center of a 28 cm diameter water sphere. Monte Carlo simulations were performed using MCNP5 codes, validated by simulating irradiations with analytical solutions. Monoenergetic x-rays ranging from 35 to 150 keV were used to simulate exposures to spheres containing contrast agent with iodine concentrations ranging from 1 to 100 mg/ml. Relative values of energy imparted to the contrast sphere, as well as to the whole phantom, were calculated. Changes in patterns of energy deposition around the contrast sphere were also investigated. Results: Small contrast spheres can increase local absorbed dose by a factor of 13, but the corresponding increase in total energy absorbed was negligible (<1%). The highest localized dose increases were found to occur at incident photon energies of about 60 keV. For a concentration of about 10 mg/ml, typical of clinical practice, localized absorbed doses were generally increased by about a factor of two. At this concentration of 10 mg/ml, the maximum increase in total energy deposition in the phantom was only 6%. These simulations demonstrated that increases in contrast sphere doses were offset by corresponding dose reductions at distal and posterior locations. Conclusions: Adding iodine can result in values of localized absorbed dose increasing by more than an order of magnitude, but the total energy deposition is generally very modest (i.e., <10%). Their data show that adding iodine primarily changes the pattern of energy deposition in the irradiated region, rather than increasing patient doses per se.

  18. Performance evaluation of iterative reconstruction algorithms for achieving CT radiation dose reduction - a phantom study.

    PubMed

    Dodge, Cristina T; Tamm, Eric P; Cody, Dianna D; Liu, Xinming; Jensen, Corey T; Wei, Wei; Kundra, Vikas; Rong, X John

    2016-03-08

    improved with increasing dose and pitch. Unlike FBP, MBIR and ASiR may have the potential for patient imaging at around 1 mGy CTDIvol. The improved low-contrast detectability observed with MBIR, especially at low-dose levels, indicate the potential for considerable dose reduction.

  19. Determining Effective Methadone Doses for Individual Opioid-Dependent Patients

    PubMed Central

    Trafton, Jodie A; Minkel, Jared; Humphreys, Keith

    2006-01-01

    Background Randomized clinical trials of methadone maintenance have found that on average high daily doses are more effective for reducing heroin use, and clinical practice guidelines recommend 60 mg/d as a minimum dosage. Nevertheless, many clinicians report that some patients can be stably maintained on lower methadone dosages to optimal effect, and clinic dosing practices vary substantially. Studies of individual responses to methadone treatment may be more easily translated into clinical practice. Methods and Findings A volunteer sample of 222 opioid-dependent US veterans initiating methadone treatment was prospectively observed over the year after treatment entry. In the 168 who achieved at least 1 mo of heroin abstinence, methadone dosages on which patients maintained heroin-free urine samples ranged from 1.5 mg to 191.2 mg (median = 69 mg). Among patients who achieved heroin abstinence, higher methadone dosages were predicted by having a diagnosis of posttraumatic stress disorder or depression, having a greater number of previous opioid detoxifications, living in a region with lower average heroin purity, attending a clinic where counselors discourage dosage reductions, and staying in treatment longer. These factors predicted 42% of the variance in dosage associated with heroin abstinence. Conclusions Effective and ineffective methadone dosages overlap substantially. Dosing guidelines should focus more heavily on appropriate processes of dosage determination rather than solely specifying recommended dosages. To optimize therapy, methadone dosages must be titrated until heroin abstinence is achieved. PMID:16448216

  20. Radiation Dose Reduction Efficiency of Buildings after the Accident at the Fukushima Daiichi Nuclear Power Station

    PubMed Central

    Monzen, Satoru; Hosoda, Masahiro; Osanai, Minoru; Tokonami, Shinji

    2014-01-01

    Numerous radionuclides were released from the Fukushima Daiichi Nuclear Power Station (F1-NPS) in Japan following the magnitude 9.0 earthquake and tsunami on March 11, 2011. Local residents have been eager to calculate their individual radiation exposure. Thus, absorbed dose rates in the indoor and outdoor air at evacuation sites in the Fukushima Prefecture were measured using a gamma-ray measuring devices, and individual radiation exposure was calculated by assessing the radiation dose reduction efficiency (defined as the ratio of absorbed dose rate in the indoor air to the absorbed dose rate in the outdoor air) of wood, aluminum, and reinforced concrete buildings. Between March 2011 and July 2011, dose reduction efficiencies of wood, aluminum, and reinforced concrete buildings were 0.55±0.04, 0.15±0.02, and 0.19±0.04, respectively. The reduction efficiency of wood structures was 1.4 times higher than that reported by the International Atomic Energy Agency. The efficiency of reinforced concrete was similar to previously reported values, whereas that of aluminum structures has not been previously reported. Dose reduction efficiency increased in proportion to the distance from F1-NPS at 8 of the 18 evacuation sites. Time variations did not reflect dose reduction efficiencies at evacuation sites although absorbed dose rates in the outdoor air decreased. These data suggest that dose reduction efficiency depends on structure types, levels of contamination, and evacuee behaviors at evacuation sites. PMID:24999992

  1. Radiation dose reduction efficiency of buildings after the accident at the Fukushima Daiichi Nuclear Power Station.

    PubMed

    Monzen, Satoru; Hosoda, Masahiro; Osanai, Minoru; Tokonami, Shinji

    2014-01-01

    Numerous radionuclides were released from the Fukushima Daiichi Nuclear Power Station (F1-NPS) in Japan following the magnitude 9.0 earthquake and tsunami on March 11, 2011. Local residents have been eager to calculate their individual radiation exposure. Thus, absorbed dose rates in the indoor and outdoor air at evacuation sites in the Fukushima Prefecture were measured using a gamma-ray measuring devices, and individual radiation exposure was calculated by assessing the radiation dose reduction efficiency (defined as the ratio of absorbed dose rate in the indoor air to the absorbed dose rate in the outdoor air) of wood, aluminum, and reinforced concrete buildings. Between March 2011 and July 2011, dose reduction efficiencies of wood, aluminum, and reinforced concrete buildings were 0.55 ± 0.04, 0.15 ± 0.02, and 0.19 ± 0.04, respectively. The reduction efficiency of wood structures was 1.4 times higher than that reported by the International Atomic Energy Agency. The efficiency of reinforced concrete was similar to previously reported values, whereas that of aluminum structures has not been previously reported. Dose reduction efficiency increased in proportion to the distance from F1-NPS at 8 of the 18 evacuation sites. Time variations did not reflect dose reduction efficiencies at evacuation sites although absorbed dose rates in the outdoor air decreased. These data suggest that dose reduction efficiency depends on structure types, levels of contamination, and evacuee behaviors at evacuation sites.

  2. Dose reduction for cardiac CT using a registration-based approach

    SciTech Connect

    Wierzbicki, Marcin; Guiraudon, Gerard M.; Jones, Douglas L.; Peters, Terry

    2007-06-15

    Two reasons for the recent rise in radiation exposure from CT are increases in its clinical applicability and the desire to maintain high SNR while acquiring smaller voxels. To address this emerging dose problem, several strategies for reducing patient exposure have already been proposed. One method employed in cardiac imaging is ECG-driven modulation of the tube current between 100% at one time point in the cardiac cycle and a reduced fraction at the remaining phases. In this paper, we describe how images obtained during such acquisition can be used to reconstruct 4D data of consistent high quality throughout the cardiac cycle. In our approach, we assume that the mid-diastole (MD) phase is imaged with full dose. The MD image is then independently registered to lower dose images (lower SNR) at other frames, resulting in a set of transformations. Finally, the transformations are used to warp the MD frame through the cardiac cycle to generate the full 4D image. In addition, the transformations may be interpolated to increase the temporal sampling or to generate images at arbitrary time points. Our approach was validated using various data obtained with simulated and scanner-implemented dose modulation. We determined that as little as 10% of the total dose was required to reproduce full quality images with a 1 mm spatial error and an error in intensity values on the order of the image noise. Thus, our technique offers considerable dose reductions compared to standard imaging protocols, with minimal effects on the quality of the final data.

  3. Dose reduction for cardiac CT using a registration-based approach.

    PubMed

    Wierzbicki, Marcin; Guiraudon, Gérard M; Jones, Douglas L; Peters, Terry

    2007-06-01

    Two reasons for the recent rise in radiation exposure from CT are increases in its clinical applicability and the desire to maintain high SNR while acquiring smaller voxels. To address this emerging dose problem, several strategies for reducing patient exposure have already been proposed. One method employed in cardiac imaging is ECG-driven modulation of the tube current between 100% at one time point in the cardiac cycle and a reduced fraction at the remaining phases. In this paper, we describe how images obtained during such acquisition can be used to reconstruct 4D data of consistent high quality throughout the cardiac cycle. In our approach, we assume that the middiastole (MD) phase is imaged with full dose. The MD image is then independently registered to lower dose images (lower SNR) at other frames, resulting in a set of transformations. Finally, the transformations are used to warp the MD frame through the cardiac cycle to generate the full 4D image. In addition, the transformations may be interpolated to increase the temporal sampling or to generate images at arbitrary time points. Our approach was validated using various data obtained with simulated and scanner-implemented dose modulation. We determined that as little as 10% of the total dose was required to reproduce full quality images with a 1 mm spatial error and an error in intensity values on the order of the image noise. Thus, our technique offers considerable dose reductions compared to standard imaging protocols, with minimal effects on the quality of the final data.

  4. Decreasing Methadone Dose Via Anxiety Reduction: A Treatment Manual.

    ERIC Educational Resources Information Center

    Kushner, Marlene; And Others

    This manual describes a Relaxation-Information Presentation program based on the clinical observation that anxiety is a serious barrier to detoxification for many methadone clients, and on experimental evidence indicating that expectations may play a greater role in the discomfort experienced during detoxification than the actual methadone dose.…

  5. Reduction of absorbed doses in radiography of the facial skeleton

    SciTech Connect

    Julin, P.; Kraepelien, T.

    1984-11-01

    Radiation absorbed doses from radiography of the paranasal sinuses and the facial skeleton were measured with thermoluminescent dosimeters (TLD) on a phantom head using high-sensitivity screens in an Orbix stand. The entrance doses to the skin of the head ranged from 0.31 to 2.9 mGy per exposure. The absorbed dose from a full series of sinus exposures averaged 0.33 mGy for the oral mucous membrane, 0.33 mGy for the maxillary sinus mucous membrane, 0.11 mGy for the parotid gland, 0.15 mGy for the submandibular gland, 0.61 mGy for the eye lens, and 0.75 mGy for the thyroid gland region. A leaded soft collar adapted to the thyroid region reduced the thyroid doses by more than one order of magnitude, but also reduced the image field. The mean energy imparted from a full series of paranasal sinus projections was 4.8 mJ and from a total series of the facial skeleton, 7.9 mJ.

  6. Patient doses using multidetector computed tomography scanners in Kenya.

    PubMed

    Korir, G K; Wambani, J S; Korir, I K

    2012-08-01

    Assessment of patient dose attributed to multislice computed tomography (CT) examination. A questionnaire method was developed and used in recording the patient dose and scanning parameters for the head, chest, abdomen and lumbar spine examinations. The patient doses due to brain, chest and abdomen examination were above the international diagnostic reference levels (DRLs) by factors of between one and four. The study demonstrated that the use of multislice CT elevates patient radiation dose, justifying the need for local optimised scanning protocols and the use of institutional DRL for dose management without affecting diagnostic image quality.

  7. SU-C-12A-07: Effect of Vertical Position On Dose Reduction Using X-Care

    SciTech Connect

    Silosky, M; Marsh, R

    2014-06-01

    Purpose: Reduction of absorbed dose to radiosensitive tissues is an important goal in diagnostic radiology. Siemens Medical has introduced a technique (X-CARE) to lower CT dose to anterior anatomy by reducing the tube current during 80° of rotation over radiosensitive tissues. Phantom studies have shown 30-40% dose reduction when phantoms are positioned at isocenter. However, for CT face and sinus exams, the center of the head is commonly positioned below isocenter. This work investigated the effects of vertical patient positioning on dose reduction using X-CARE. Methods: A 16cm Computed Tomography Dose Index phantom was scanned on a Siemens Definition Flash CT scanner using a routine head protocol, with the phantom positioned at scanner isocenter. Optically stimulated luminescent dosimeters were placed on the anterior and posterior sides of the phantom. The phantom was lowered in increments of 2cm and rescanned, up to 8cm below isocenter. The experiment was then repeated using the same scan parameters but adding the X-CARE technique. The mean dosimeter counts were determined for each phantom position, and the difference between XCARE and routine scans was plotted as a function of distance from isocenter. Results: With the phantom positioned at isocenter, using XCARE reduced dose to the anterior side of the phantom by 40%, compared to dose when X-CARE was not used. Positioned below isocenter, anterior dose was reduced by only 20-27%. Additionally, using X-CARE at isocenter reduced dose to the anterior portion of the phantom by 45.6% compared to scans performed without X-CARE 8cm below isocenter. Conclusion: While using X-CARE substantially reduced dose to the anterior side of the phantom, this effect was diminished when the phantom was positioned below isocenter, simulating common practice for face and sinus scans. This indicates that centering the head in the gantry will maximize the effect of X-CARE.

  8. Radiation Dose Reduction during Radial Cardiac Catheterization: Evaluation of a Dedicated Radial Angiography Absorption Shielding Drape.

    PubMed

    Ertel, Andrew; Nadelson, Jeffrey; Shroff, Adhir R; Sweis, Ranya; Ferrera, Dean; Vidovich, Mladen I

    2012-01-01

    Objectives. Radiation scatter protection shield drapes have been designed with the goal of decreasing radiation dose to the operators during transfemoral catheterization. We sought to investigate the impact on operator radiation exposure of various shielding drapes specifically designed for the radial approach. Background. Radial access for cardiac catheterization has increased due to improved patient comfort and decreased bleeding complications. There are concerns for increased radiation exposure to patients and operators. Methods. Radiation doses to a simulated operator were measured with a RadCal Dosimeter in the cardiac catheterization laboratory. The mock patient was a 97.5 kg fission product phantom. Three lead-free drape designs were studied. The drapes were placed just proximal to the right wrist and extended medially to phantom's trunk. Simulated diagnostic coronary angiography included 6 minutes of fluoroscopy time and 32 seconds of cineangiography time at 4 standard angulated views (8 s each), both 15 frames/s. ANOVA with Bonferroni correction was used for statistical analysis. Results. All drape designs led to substantial reductions in operator radiation exposure compared to control (P < 0.0001). The greatest decrease in radiation exposure (72%) was with the L-shaped design. Conclusions. Dedicated radial shielding drapes decrease radiation exposure to the operator by up to 72% during simulated cardiac catheterization.

  9. Preliminary design review report for K Basin Dose Reduction Project

    SciTech Connect

    Blackburn, L.D.

    1996-01-01

    The strategy for reducing radiation dose, originating from radionuclides absorbed in the K East Basin concrete, is to raise the pool water level to provide additional shielding. This report documents a preliminary design review conducted to ensure that design approaches for cleaning/coating basin walls and modifying other basin components were appropriate. The conclusion of this review was that design documents presently conclusion of this review was that design documents presently completed or in process of modification are and acceptable basis for proceeding to complete the design.

  10. Real-Time Patient Radiation Dose Monitoring System Used in a Large University Hospital.

    PubMed

    Kim, Jungsu; Yoon, Yongsu; Seo, Deoknam; Kwon, Soonmu; Shim, Jina; Kim, Jungmin

    2016-10-01

    Radiation dose monitoring in medical imaging examination areas is mandatory for the reduction of patient radiation exposure. Recently, dose monitoring techniques that use digital imaging and communications in medicine (DICOM) dose structured reports (SR) have been introduced. The present paper discusses the setup of a radiation dose monitoring system based on DICOM data from university hospitals in Korea. This system utilizes the radiation dose data-archiving method of standard DICOM dose SR combined with a DICOM modality performed procedure step (MPPS). The analysis of dose data based on a method utilizing DICOM tag information is proposed herein. This method supports the display of dose data from non-dosimeter-attached X-ray equipment. This system tracks data from 62 pieces of equipment to analyze digital radiographic, mammographic, mobile radiographic, CT, PET-CT, angiographic, and fluorographic modalities.

  11. AN APPROACH TO REDUCTION OF UNCERTAINTIES IN INTERNAL DOSES RECONSTRUCTED FOR THE TECHA RIVER POPULATION

    SciTech Connect

    Degteva, M. O.; Shagina, N. B.; Tolstykh, E. I.; Bougrov, N. G.; Zalyapin, V. I.; Anspaugh, L. R.; Napier, Bruce A.

    2007-12-01

    A methodology is being developing for reduction of uncertainties in estimates of internal dose for residents of the Techa Riverside communities, who were exposed as a result of releases of radionuclides from the Mayak plutonium-production facility in 1949–1956. The “Techa River Dosimetry System” (TRDS) was specifically elaborated for reconstruction of doses. A preliminary analysis of uncertainty for doses estimated using the current version of the TRDS showed large ranges in the uncertainty of internal absorbed dose and led to suggestions of methods to reduce uncertainties. The new methodological approaches described in this paper will allow for significant reduction of uncertainties of 90Sr-dose. The major sources of reduction are in making use of individual measured values of 90Sr and through development of a Household Registry to associate unmeasured persons with measured persons living in the same household(s).

  12. Study of the radiation dose reduction capability of a CT reconstruction algorithm: LCD performance assessment using mathematical model observers

    NASA Astrophysics Data System (ADS)

    Fan, Jiahua; Tseng, Hsin-Wu; Kupinski, Matthew; Cao, Guangzhi; Sainath, Paavana; Hsieh, Jiang

    2013-03-01

    Radiation dose on patient has become a major concern today for Computed Tomography (CT) imaging in clinical practice. Various hardware and algorithm solutions have been designed to reduce dose. Among them, iterative reconstruction (IR) has been widely expected to be an effective dose reduction approach for CT. However, there is no clear understanding on the exact amount of dose saving an IR approach can offer for various clinical applications. We know that quantitative image quality assessment should be task-based. This work applied mathematical model observers to study detectability performance of CT scan data reconstructed using an advanced IR approach as well as the conventional filtered back-projection (FBP) approach. The purpose of this work is to establish a practical and robust approach for CT IR detectability image quality evaluation and to assess the dose saving capability of the IR method under study. Low contrast (LC) objects imbedded in head size and body size phantoms were imaged multiple times with different dose levels. Independent signal present and absent pairs were generated for model observer study training and testing. Receiver Operating Characteristic (ROC) curves for location known exact and location ROC (LROC) curves for location unknown as well as their corresponding the area under the curve (AUC) values were calculated. Results showed approximately 3 times dose reduction has been achieved using the IR method under study.

  13. Preliminary validation of a new methodology for estimating dose reduction protocols in neonatal chest computed radiographs

    NASA Astrophysics Data System (ADS)

    Don, Steven; Whiting, Bruce R.; Hildebolt, Charles F.; Sehnert, W. James; Ellinwood, Jacquelyn S.; Töpfer, Karin; Masoumzadeh, Parinaz; Kraus, Richard A.; Kronemer, Keith A.; Herman, Thomas; McAlister, William H.

    2006-03-01

    The risk of radiation exposure is greatest for pediatric patients and, thus, there is a great incentive to reduce the radiation dose used in diagnostic procedures for children to "as low as reasonably achievable" (ALARA). Testing of low-dose protocols presents a dilemma, as it is unethical to repeatedly expose patients to ionizing radiation in order to determine optimum protocols. To overcome this problem, we have developed a computed-radiography (CR) dose-reduction simulation tool that takes existing images and adds synthetic noise to create realistic images that correspond to images generated with lower doses. The objective of our study was to determine the extent to which simulated, low-dose images corresponded with original (non-simulated) low-dose images. To make this determination, we created pneumothoraces of known volumes in five neonate cadavers and obtained images of the neonates at 10 mR, 1 mR and 0.1 mR (as measured at the cassette plate). The 10-mR exposures were considered "relatively-noise-free" images. We used these 10 mR-images and our simulation tool to create simulated 0.1- and 1-mR images. For the simulated and original images, we identified regions of interest (ROI) of the entire chest, free-in-air region, and liver. We compared the means and standard deviations of the ROI grey-scale values of the simulated and original images with paired t tests. We also had observers rate simulated and original images for image quality and for the presence or absence of pneumothoraces. There was no statistically significant difference in grey-scale-value means nor standard deviations between simulated and original entire chest ROI regions. The observer performance suggests that an exposure >=0.2 mR is required to detect the presence or absence of pneumothoraces. These preliminary results indicate that the use of the simulation tool is promising for achieving ALARA exposures in children.

  14. Patient radiation doses for electron beam CT

    SciTech Connect

    Castellano, Isabel A.; Dance, David R.; Skinner, Claire L.; Evans, Phil M.

    2005-08-15

    A Monte Carlo based computer model has been developed for electron beam computed tomography (EBCT) to calculate organ and effective doses in a humanoid hermaphrodite phantom. The program has been validated by comparison with experimental measurements of the CT dose index in standard head and body CT dose phantoms; agreement to better than 8% has been found. The robustness of the model has been established by varying the input parameters. The amount of energy deposited at the 12:00 position of the standard body CT dose phantom is most susceptible to rotation angle, whereas that in the central region is strongly influenced by the beam quality. The program has been used to investigate the changes in organ absorbed doses arising from partial and full rotation about supine and prone subjects. Superficial organs experience the largest changes in absorbed dose with a change in subject orientation and for partial rotation. Effective doses for typical clinical scan protocols have been calculated and compared with values obtained using existing dosimetry techniques based on full rotation. Calculations which make use of Monte Carlo conversion factors for the scanner that best matches the EBCT dosimetric characteristics consistently overestimate the effective dose in supine subjects by typically 20%, and underestimate the effective dose in prone subjects by typically 13%. These factors can therefore be used to correct values obtained in this way. Empirical dosimetric techniques based on the dose-length product yield errors as great as 77%. This is due to the sensitivity of the dose length product to individual scan lengths. The magnitude of these errors is reduced if empirical dosimetric techniques based on the average absorbed dose in the irradiated volume (CTDI{sub vol}) are used. Therefore conversion factors specific to EBCT have been calculated to convert the CTDI{sub vol} to an effective dose.

  15. Feasibility of normal tissue dose reduction in radiotherapy using low strength magnetic field

    PubMed Central

    Shin, Youngseob; Jung, In-Hye; Kwak, Jungwon

    2015-01-01

    Purpose Toxicity of mucosa is one of the major concerns of radiotherapy (RT), when a target tumor is located near a mucosal lined organ. Energy of photon RT is transferred primarily by secondary electrons. If these secondary electrons could be removed in an internal cavity of mucosal lined organ, the mucosa will be spared without compromising the target tumor dose. The purpose of this study was to present a RT dose reduction in near target inner-surface (NTIS) of internal cavity, using Lorentz force of magnetic field. Materials and Methods Tissue equivalent phantoms, composed with a cylinder shaped internal cavity, and adjacent a target tumor part, were developed. The phantoms were irradiated using 6 MV photon beam, with or without 0.3 T of perpendicular magnetic field. Two experimental models were developed: single beam model (SBM) to analyze central axis dose distributions and multiple beam model (MBM) to simulate a clinical case of prostate cancer with rectum. RT dose of NTIS of internal cavity and target tumor area (TTA) were measured. Results With magnetic field applied, bending effect of dose distribution was visualized. The depth dose distribution of SBM showed 28.1% dose reduction of NTIS and little difference in dose of TTA with magnetic field. In MBM, cross-sectional dose of NTIS was reduced by 33.1% with magnetic field, while TTA dose were the same, irrespective of magnetic field. Conclusion RT dose of mucosal lined organ, located near treatment target, could be modulated by perpendicular magnetic field. PMID:26484306

  16. Full dose reduction potential of statistical iterative reconstruction for head CT protocols in a predominantly pediatric population

    PubMed Central

    Mirro, Amy E.; Brady, Samuel L.; Kaufman, Robert. A.

    2016-01-01

    Purpose To implement the maximum level of statistical iterative reconstruction that can be used to establish dose-reduced head CT protocols in a primarily pediatric population. Methods Select head examinations (brain, orbits, sinus, maxilla and temporal bones) were investigated. Dose-reduced head protocols using an adaptive statistical iterative reconstruction (ASiR) were compared for image quality with the original filtered back projection (FBP) reconstructed protocols in phantom using the following metrics: image noise frequency (change in perceived appearance of noise texture), image noise magnitude, contrast-to-noise ratio (CNR), and spatial resolution. Dose reduction estimates were based on computed tomography dose index (CTDIvol) values. Patient CTDIvol and image noise magnitude were assessed in 737 pre and post dose reduced examinations. Results Image noise texture was acceptable up to 60% ASiR for Soft reconstruction kernel (at both 100 and 120 kVp), and up to 40% ASiR for Standard reconstruction kernel. Implementation of 40% and 60% ASiR led to an average reduction in CTDIvol of 43% for brain, 41% for orbits, 30% maxilla, 43% for sinus, and 42% for temporal bone protocols for patients between 1 month and 26 years, while maintaining an average noise magnitude difference of 0.1% (range: −3% to 5%), improving CNR of low contrast soft tissue targets, and improving spatial resolution of high contrast bony anatomy, as compared to FBP. Conclusion The methodology in this study demonstrates a methodology for maximizing patient dose reduction and maintaining image quality using statistical iterative reconstruction for a primarily pediatric population undergoing head CT examination. PMID:27056425

  17. Serum phosphorus reduction in dialysis patients treated with cinacalcet for secondary hyperparathyroidism results mainly from parathyroid hormone reduction

    PubMed Central

    Zitt, Emanuel; Fouque, Denis; Jacobson, Stefan H.; Malberti, Fabio; Ryba, Miroslav; Ureña, Pablo; Rix, Marianne; Dehmel, Bastian; Manamley, Nick; Vervloet, Marc

    2013-01-01

    Background The calcimimetic cinacalcet lowers parathyroid hormone (PTH), calcium (Ca) and phosphorus (P) in dialysis patients with secondary hyperparathyroidism (SHPT). We explored serum P changes in dialysis patients treated with cinacalcet, while controlling for vitamin D sterol and phosphate binder (PB) changes, based on data from the pan-European observational study ECHO. Methods Patients were categorized by serum P change (decreased/unchanged/increased) at 12 months after starting cinacalcet and subcategorized by vitamin D sterol and PB dose changes (decreased/unchanged/increased). The impact of PTH, Ca and P, and vitamin D sterol, PB and cinacalcet doses (absolute values and/or change) was evaluated. Predictors of P change were explored using univariate and multivariate general linear models (GLM) and logistic regression analysis. Results At Month 12, 661 (41%) of 1607 patients had decreased, 61 (4%) unchanged and 400 (25%) increased serum P, while 485 patients had missing data. In 45% of the patients with serum P reduction, vitamin D was either increased or unchanged and P binders decreased or unchanged. PTH was a key predictor of serum P reduction, with an estimated 3% decrease in P per 10% reduction in PTH. Changes in vitamin D sterol and PB doses were not generally significant factors in GLM and regression analyses. Conclusions The serum P reduction observed in a significant proportion of dialysis patients after adding cinacalcet to an existing therapeutic regimen for SHPT appears to result mainly from PTH reduction, rather than from changes in vitamin D sterol or PB doses. Financial support for the ECHO study was provided by Amgen. PMID:23717787

  18. Are phantoms useful for predicting the potential of dose reduction in full-field digital mammography?

    NASA Astrophysics Data System (ADS)

    Gennaro, Gisella; Katz, Luc; Souchay, Henri; Alberelli, Claudio; di Maggio, Cosimo

    2005-04-01

    A phantom study was performed in full-field digital mammography to investigate the opportunity and the magnitude of a possible dose reduction that would leave the image quality above the accepted thresholds associated with some classical phantoms. This preliminary work is intended to lay the groundwork for a future clinical study on the impact of dose reduction on clinical results. Three different mammography phantoms (ACR RMI 156, CIRS 11A and CDMAM 3.4) were imaged by a full-field digital mammography unit (GE Senographe 2000D) at different dose levels. Images were rated by three observers with softcopy reading and scoring methods specific to each phantom. Different types of data analysis were applied to the ACR (American College of Radiology) and the other two phantoms, respectively. With reference to the minimum acceptance score in screen/film accreditation programmes, the ACR phantom showed that about 45% dose reduction could be applied, while keeping the phantom scores above that threshold. A relative comparison was done for CIRS and CDMAM, for which no threshold is defined. CIRS scoring remained close to the reference level down to 40% dose reduction, the inter- and intra-observer variability being the main source of uncertainty. Contrast-detail curves provided by CDMAM overlapped down to 50% dose reduction, at least for object contrast values ranging between 30% and 3%. This multi-phantom study shows the potential of further reducing the dose in full-field digital mammography beyond the current values. A common dose reduction factor around 50% seems acceptable for all phantoms. However, caution is required before extrapolating the results for clinical use, given the limitations of these widely used phantoms, mainly related to their limited dynamic range and uniform background.

  19. Monday, Wednesday, and Friday dosing of rosuvastatin in patients previously intolerant to statin therapy.

    PubMed

    Mackie, Benjamin D; Satija, Sameer; Nell, Christine; Miller, Joseph; Sperling, Laurence S

    2007-01-15

    Statins are normally administered for the treatment of dyslipidemia on a daily basis. This standard dosing regimen is well tolerated by most patients. Occasionally, patients discontinue therapy secondary to side effects, most commonly myalgias. We describe 2 patients who were unable to tolerate daily atorvastatin therapy secondary to myalgias and were subsequently treated with rosuvastatin administered on Mondays, Wednesdays, and Fridays, with resolution of adverse effects. Significant reductions in serum low-density lipoprotein cholesterol levels were observed in the 2 patients despite the alternate-day dosing regimen. Rosuvastatin was chosen because of its long half-life (19 hours) and very high potency.

  20. The effect of dose reduction and feasibility of edge-preserving noise reduction on the detection of liver lesions using MSCT.

    PubMed

    Wessling, Johannes; Esseling, Rainer; Raupach, Rainer; Fockenberg, Stefanie; Osada, Nani; Gerss, Joachim; Heindel, Walter; Fischbach, Roman

    2007-07-01

    The purpose of this study was to assess the effect of dose reduction and the potential of noise reduction filters on image quality and the detection of liver lesions using MSCT. Twenty-nine patients with a total of 40 liver lesions underwent 16-slice CT (120 kV; 180 mAs). Virtual noise was added to CT raw datasets simulating effective mAs levels of 155, 130, 105, 80, 55, 30 and 10 mAs. All datasets were post-processed with an edge-preserving noise-reduction filter (ANR-3D), yielding a total of 15 datasets per patient. Ten radiologists performed independent evaluations of image quality, the presence of liver lesions and diagnostic confidence. Quantitative noise and contrast-to-noise ratios (CNR) were obtained. Superior image quality (P < 0.02), reduction of image noise (P < 0.001) and the increase of lesion-to-liver CNR (P < 0.001) were observed in images processed with the ANR-3D filter. Sensitivity for lesion detection remained unchanged down to 105 mAs (CTDI(w) 6.6 mGy) without filter and 80 mAs (CTDI(w) 5.1 mGy) with ANR-3D. Confidence was rated significantly higher for datasets reconstructed with ANR-3D. The use of a noise-reducing, but edge-preserving filter (ANR-3D) is a promising option to reduce further the radiation dose in liver CT.

  1. Measuring radiation dose to patients undergoing fluoroscopically-guided interventions

    NASA Astrophysics Data System (ADS)

    Lubis, L. E.; Badawy, M. K.

    2016-03-01

    The increasing prevalence and complexity of fluoroscopically guided interventions (FGI) raises concern regarding radiation dose to patients subjected to the procedure. Despite current evidence showing the risk to patients from the deterministic effects of radiation (e.g. skin burns), radiation induced injuries remain commonplace. This review aims to increase the awareness surrounding radiation dose measurement for patients undergoing FGI. A review of the literature was conducted alongside previous researches from the authors’ department. Studies pertaining to patient dose measurement, its formalism along with current advances and present challenges were reviewed. Current patient monitoring techniques (using available radiation dosimeters), as well as the inadequacy of accepting displayed dose as patient radiation dose is discussed. Furthermore, advances in real-time patient radiation dose estimation during FGI are considered. Patient dosimetry in FGI, particularly in real time, remains an ongoing challenge. The increasing occurrence and sophistication of these procedures calls for further advances in the field of patient radiation dose monitoring. Improved measuring techniques will aid clinicians in better predicting and managing radiation induced injury following FGI, thus improving patient care.

  2. Influence of scatter reduction method and monochromatic beams on image quality and dose in mammography.

    PubMed

    Moeckli, Raphaël; Verdun, Francis R; Fiedler, Stefan; Pachoud, Marc; Bulling, Shelley; Schnyder, Pierre; Valley, Jean-François

    2003-12-01

    In mammography, the image contrast and dose delivered to the patient are determined by the x-ray spectrum and the scatter to primary ratio S/P. Thus the quality of the mammographic procedure is highly dependent on the choice of anode and filter material and on the method used to reduce the amount of scattered radiation reaching the detector. Synchrotron radiation is a useful tool to study the effect of beam energy on the optimization of the mammographic process because it delivers a high flux of monochromatic photons. Moreover, because the beam is naturally flat collimated in one direction, a slot can be used instead of a grid for scatter reduction. We have measured the ratio S/P and the transmission factors for grids and slots for monoenergetic synchrotron radiation. In this way the effect of beam energy and scatter rejection method were separated, and their respective importance for image quality and dose analyzed. Our results show that conventional mammographic spectra are not far from optimum and that the use of a slot instead of a grid has an important effect on the optimization of the mammographic process. We propose a simple numerical model to quantify this effect.

  3. 28-day intraocular pressure reduction with a single dose of brimonidine tartrate-loaded microspheres.

    PubMed

    Fedorchak, Morgan V; Conner, Ian P; Medina, Carlos A; Wingard, Jeremy B; Schuman, Joel S; Little, Steven R

    2014-08-01

    Treatment of glaucoma by intraocular pressure (IOP) reduction is typically accomplished through the administration of eye drops, the difficult and frequent nature of which contributes to extremely low adherence rates. Poor adherence to topical treatment regimens in glaucoma patients can lead to irreversible vision loss and increased treatment costs. Currently there are no approved treatments for glaucoma that address the inherent inefficiencies in drug delivery and patient adherence. Brimonidine tartrate (BT), a common glaucoma medication, requires dosing every 8-12 h, with up to 97% of patients not taking it as prescribed. This study provides proof-of-principle testing of a controlled release BT formulation. BT was encapsulated in poly(lactic-co-glycolic) acid microspheres and drug release was quantified using UV-Vis spectroscopy. For in vivo studies, rabbits were randomized to receive a single subconjunctival injection of blank (no drug) or BT-loaded microspheres or twice daily topical 0.2% BT drops. The microspheres released an average of 2.1 ± 0.37 μg BT/mg microspheres/day in vitro. In vivo, the percent decrease in IOP from baseline was significantly greater in the treated eye for both topical drug and drug-loaded microspheres versus blank microspheres throughout the 4-week study, with no evidence of migration or foreign body response. IOP measurements in the contralateral, untreated eyes also suggested a highly localized effect from the experimental treatment. A treatment designed using the release systems described in this study would represent a vast improvement over the current clinical standard of 56-84 topical doses over 28 days.

  4. SU-F-BRF-11: Dose Rearrangement in High Dose Locally Advanced Lung Patients Based On Perfusion Imaging

    SciTech Connect

    Matrosic, C; Jarema, D; Kong, F; McShan, D; Stenmark, M; Owen, D; Ten Haken, R; Matuszak, M

    2014-06-15

    Purpose: The use of mean lung dose (MLD) limits allows individualization of lung patient tumor doses at safe levels. However, MLD does not account for local lung function differences between patients, leading to toxicity variability at the same MLD. We investigated dose rearrangement to minimize dose to functional lung, as measured by perfusion SPECT, while maintaining target coverage and conventional MLD limits. Methods: Retrospective plans were optimized for 15 locally advanced NSCLC patients enrolled in a prospective imaging trial. A priority-based optimization system was used. The baseline priorities were (1) meet OAR dose constraints, (2) maximize target gEUD, and (3) minimize physical MLD. As a final step, normal tissue doses were minimized. To determine the benefit of rearranging dose using perfusion SPECT, plans were reoptimized to minimize functional lung gEUD as the 4th priority. Results: When only minimizing physical MLD, the functional lung gEUD was 10.8+/−5.0 Gy (4.3–19.8 Gy). Only 3/15 cases showed a decrease in functional lung gEUD of ≥4% when rearranging dose to minimize functional gEUD in the cost function (10.5+/−5.0 Gy range 4.3−19.7). Although OAR constraints were respected, the dose rearrangement resulted in ≥10% increases in gEUD to an OAR in 4/15 cases. Only slight reductions in functional lung gEUD were noted when omitting the minimization of physical MLD, suggesting that constraining the target gEUD minimizes the potential to redistribute dose. Conclusion: Prioritydriven optimization permits the generation of plans that respect traditional OAR limits and target coverage, but with the ability to rearrange dose based on functional imaging. The latter appears to be limited due to the decreased solution space when constraining target coverage. Since dose rearrangement may increase dose to other OARs, it is also worthwhile to investigate global biomarkers of lung toxicity to further individualize treatment in this population

  5. Infliximab Dose Reduction Sustains the Clinical Treatment Effect in Active HLAB27 Positive Ankylosing Spondylitis: A Two-Year Pilot Study

    PubMed Central

    Mörck, Boel; Bremell, Tomas; Forsblad-d'Elia, Helena

    2013-01-01

    The rationale of the study was to evaluate the efficacy of infliximab (IFX) treatment in patients with ankylosing spondylitis (AS) and to determine whether IFX dose reduction and interval extension sustains the treatment effect. Nineteen patients were included and treated with IFX 5 mg/kg every 6 weeks for 56 weeks. All patients concomitantly received MTX with median dose 7.5 mg/weekly. During the second year, the IFX dose was reduced to 3 mg/kg every 8 weeks. Eighteen patients completed the 1-year and 15 patients the 2-year trial. The ≥50% improvement at week 16 from baseline of BASDAI was achieved in 16/19 (84%) patients. Significant reductions in BASDAI, BASFI, and BASMI scores, decrease in ESR and CRP, and improvement in SF-36 were observed at weeks 16 and 56. The MRI-defined inflammatory changes in the sacroiliac joints disappeared in 10/15 patients (67%) already at 16 weeks. IFX treatment effect was sustained throughout the second year after IFX dose reduction and interval extension. We conclude that IFX treatment is effective in well-established active AS and a dose reduction sustains the treatment effect. These observations are of clinical importance and open the opportunity to reduce the drug costs. This trial is registered with ClinicalTrials.gov NCT01850121. PMID:24089587

  6. Outcomes for newly diagnosed patients with acute myeloid leukemia dosed on actual or adjusted body weight

    PubMed Central

    Bivona, Cory; Rockey, Michelle; Henry, Dave; Grauer, Dennis; Abhyankar, Sunil; Aljitawi, Omar; Ganguly, Siddhartha; McGuirk, Joseph; Singh, Anurag; Lin, Tara L.

    2015-01-01

    Purpose Data from solid tumor malignancies suggest that actual body weight (ABW) dosing improves overall outcomes. There is the potential to compromise efficacy when chemotherapy dosages are reduced, but the impact of dose adjustment on clinical response and toxicity in hematologic malignancies is unknown. The purpose of this study was to evaluate the outcomes of utilizing a percent of ABW for acute myeloid leukemia (AML) induction chemotherapy dosing. Methods This retrospective, single-center study included 146 patients who received 7 + 3 induction (cytarabine and anthracycline) for treatment of AML. Study design evaluated the relationship between percentage of ABW dosing and complete response (CR) rates in patients newly diagnosed with AML. Results Percentage of ABW dosing did not influence CR rates in patients undergoing induction chemotherapy for AML (p = 0.83); nor did it influence rate of death at 30 days or relapse at 6 months (p = 0.94). When comparing patients dosed at 90–100 % of ABW compared to <90 % ABW, CR rates were not significantly different in patients classified as poor risk (p = 0.907). All favorable risk category patients obtained CR. Conclusions Preemptive dose reductions for obesity did not influence CR rates for patients with AML undergoing induction chemotherapy and did not influence the composite endpoint of death at 30 days or disease relapse at 6 months. PMID:26231954

  7. Objective assessment of image quality and dose reduction in CT iterative reconstruction

    SciTech Connect

    Vaishnav, J. Y. Jung, W. C.; Popescu, L. M.; Zeng, R.; Myers, K. J.

    2014-07-15

    Purpose: Iterative reconstruction (IR) algorithms have the potential to reduce radiation dose in CT diagnostic imaging. As these algorithms become available on the market, a standardizable method of quantifying the dose reduction that a particular IR method can achieve would be valuable. Such a method would assist manufacturers in making promotional claims about dose reduction, buyers in comparing different devices, physicists in independently validating the claims, and the United States Food and Drug Administration in regulating the labeling of CT devices. However, the nonlinear nature of commercially available IR algorithms poses challenges to objectively assessing image quality, a necessary step in establishing the amount of dose reduction that a given IR algorithm can achieve without compromising that image quality. This review paper seeks to consolidate information relevant to objectively assessing the quality of CT IR images, and thereby measuring the level of dose reduction that a given IR algorithm can achieve. Methods: The authors discuss task-based methods for assessing the quality of CT IR images and evaluating dose reduction. Results: The authors explain and review recent literature on signal detection and localization tasks in CT IR image quality assessment, the design of an appropriate phantom for these tasks, possible choices of observers (including human and model observers), and methods of evaluating observer performance. Conclusions: Standardizing the measurement of dose reduction is a problem of broad interest to the CT community and to public health. A necessary step in the process is the objective assessment of CT image quality, for which various task-based methods may be suitable. This paper attempts to consolidate recent literature that is relevant to the development and implementation of task-based methods for the assessment of CT IR image quality.

  8. New noise reduction method for reducing CT scan dose: Combining Wiener filtering and edge detection algorithm

    NASA Astrophysics Data System (ADS)

    Anam, Choirul; Haryanto, Freddy; Widita, Rena; Arif, Idam

    2015-09-01

    New noise reduction method for reducing dose of CT scans has been proposed. The new method is expected to address the major problems in the noise reduction algorithm, i.e. the decreasing in the spatial resolution of the image. The proposed method was developed by combining adaptive Wiener filtering and edge detection algorithms. The first step, the image was filtered with a Wiener filter. Separately, edge detection operation performed on the original image using the Prewitt method. The next step, a new image was generated based on the edge detection operation. At the edge area, the image was taken from the original image, while at the non-edge area, the image was taken from the image that had been filtered with a Wiener filter. The new method was tested on a CT image of the spatial resolution phantom, which was scanned by different current-time multiplication, namely 80, 130 and 200 mAs, while other exposure factors were kept in constant conditions. The spatial resolution phantom consists of six sets of bar pattern made of plexi-glass and separated at some distance by water. The new image quality assessed from the amount of noise and the magnitude of spatial resolution. Noise was calculated by determining the standard deviation of the homogeneous regions, while the spatial resolution was assessed by observation of the area sets of the bar pattern. In addition, to evaluate the performance of this new method has also been tested on patient CT images. From the measurements, the new method can reduce the noise to an average 64.85%, with a spatial resolution does not decrease significantly. Visually, the third set bar on the image phantom (the distance between the bar 1.0 mm) can still be distinguished, as well as on the original image. Meanwhile, if the image is only processed using Wiener filter, the second set bar (the distance between the bar 1.3 mm) are distinguishable. Testing this new method to patient image, its results in relatively the same. Thus, using this

  9. Effects of dose limits reduction on the Argentine nuclear power plants

    SciTech Connect

    Palacios, E.; Curti, A.; Massera, G.; Spano, F.; Boutet, L. )

    1993-11-01

    Occupational doses are evaluated in different stages of the fuel cycle and in the operation of nuclear power plants. Trends in individual dose distribution and collective doses are analyzed. The most contributive working conditions to collective dose are identified and the implications of dose limit reduction recommended by the ICRP in 1990 are assessed. It is concluded that no relevant difficulties should appear in accomplishing the new recommendations except for implementation at Atucha I, a nuclear power plant designed in the 1960s. Some options to reduce individual and collective doses in this plant are analyzed. The change of fuel channels by new ones free from cobalt is essential to get effective improvement of occupational exposures.

  10. A study on the indirect urea dosing method in the Selective Catalytic Reduction system

    NASA Astrophysics Data System (ADS)

    Brzeżański, M.; Sala, R.

    2016-09-01

    This article presents the results of studies on concept solution of dosing urea in a gas phase in a selective catalytic reduction system. The idea of the concept was to heat-up and evaporate the water urea solution before introducing it into the exhaust gas stream. The aim was to enhance the processes of urea converting into ammonia, what is the target reductant for nitrogen oxides treatment. The study was conducted on a medium-duty Euro 5 diesel engine with exhaust line consisting of DOC catalyst, DPF filter and an SCR system with a changeable setup allowing to dose the urea in liquid phase (regular solution) and to dose it in a gas phase (concept solution). The main criteria was to assess the effect of physical state of urea dosed on the NOx conversion ratio in the SCR catalyst. In order to compare both urea dosing methods a special test procedure was developed which consisted of six test steps covering a wide temperature range of exhaust gas generated at steady state engine operation condition. Tests were conducted for different urea dosing quantities defined by the a equivalence ratio. Based on the obtained results, a remarkable improvement in NOx reduction was found for gas urea application in comparison to the standard liquid urea dosing. Measured results indicate a high potential to increase an efficiency of the SCR catalyst by using a gas phase urea and provide the basis for further scientific research on this type of concept.

  11. SU-E-I-37: Eye Lens Dose Reduction From CT Scan Using Organ Based Tube Current Modulation

    SciTech Connect

    Liu, H; Liu, T; Xu, X; Wu, J; Zhuo, W

    2015-06-15

    Purpose: To investigate the eye lens dose reduction by CT scan with organ based tube current modulation (OBTCM) using GPU Monte Carlo code ARCHER-CT. Methods: 36 X-ray sources and bowtie filters were placed around the patient head with the projection angle interval of 10° for one rotation of CT scan, each projection was simulated respectively. The voxel eye models with high resolution(0.1mm*0.1mm*0.1mm) were used in the simulation and different tube voltage including 80kVp, 100kVp, 120kVp and 140kVp were taken into consideration. Results: The radiation doses to the eye lens increased with the tube voltage raised from 80kVp to 140kVp, and the dose results from 0° (AP) direction are much higher than those from 180° (PA) direction for all the 4 different tube voltage investigated. This 360° projection dose characteristic enables organ based TCM, which can reduce the eye lens dose by more than 55%. Conclusion: As the eye lens belongs to superficial tissues, its radiation dose to external exposure like CT is direction sensitive, and this characteristic feature makes organ based TCM to be an effective way to reduce the eye lens dose, so more clinical use of this technique were recommended. National Nature Science Foundation of China(No.11475047)

  12. Dosimetric impact of orthopedic metal artifact reduction (O-MAR) on Spine SBRT patients.

    PubMed

    Shen, Zhilei Liu; Xia, Ping; Klahr, Paul; Djemil, Toufik

    2015-09-08

    The dosimetric impact of orthopedic metal artifact reduction (O-MAR) on spine SBRT patients has not been comprehensively studied, particularly with spinal prostheses in high-dose gradient regions. Using both phantom and patient datasets, we investigated dosimetric effects of O-MAR in combination of various metal locations and dose calculation algorithms. A physical phantom, with and without a titanium insert, was scanned. A clinical patient plan was applied to the artifact-free reference, non-O-MAR, and O-MAR phantom images with the titanium located either inside or outside of the tumor. Subsequently, five clinical patient plans were calculated with pencil beam and Monte Carlo (iPlan) on non-O-MAR and O-MAR patient images using an extended CT-density table. The dose differences for phantom plans and patient plans were analyzed using dose distributions, dose-volume histograms (DVHs), gamma index, and selected dosimetric endpoints. From both phantom plans and patient plans, O-MAR did not affect dose distributions and DVHs while minimizing metal artifacts. Among patient plans, we found that, when the same dose calculation method was used, the difference in the dosimetric endpoints between non-O-MAR and O-MAR datasets were small. In conclusion, for spine SBRT patients with spinal prostheses, O-MAR image reconstruction does not affect dose calculation accuracy while minimizing metal artifacts. Therefore, O-MAR images can be safely used for clinical spine SBRT treatment planning.

  13. Projection space denoising with bilateral filtering and CT noise modeling for dose reduction in CT

    SciTech Connect

    Manduca, Armando; Yu Lifeng; Trzasko, Joshua D.; Khaylova, Natalia; Kofler, James M.; McCollough, Cynthia M.; Fletcher, Joel G.

    2009-11-15

    Purpose: To investigate a novel locally adaptive projection space denoising algorithm for low-dose CT data. Methods: The denoising algorithm is based on bilateral filtering, which smooths values using a weighted average in a local neighborhood, with weights determined according to both spatial proximity and intensity similarity between the center pixel and the neighboring pixels. This filtering is locally adaptive and can preserve important edge information in the sinogram, thus maintaining high spatial resolution. A CT noise model that takes into account the bowtie filter and patient-specific automatic exposure control effects is also incorporated into the denoising process. The authors evaluated the noise-resolution properties of bilateral filtering incorporating such a CT noise model in phantom studies and preliminary patient studies with contrast-enhanced abdominal CT exams. Results: On a thin wire phantom, the noise-resolution properties were significantly improved with the denoising algorithm compared to commercial reconstruction kernels. The noise-resolution properties on low-dose (40 mA s) data after denoising approximated those of conventional reconstructions at twice the dose level. A separate contrast plate phantom showed improved depiction of low-contrast plates with the denoising algorithm over conventional reconstructions when noise levels were matched. Similar improvement in noise-resolution properties was found on CT colonography data and on five abdominal low-energy (80 kV) CT exams. In each abdominal case, a board-certified subspecialized radiologist rated the denoised 80 kV images markedly superior in image quality compared to the commercially available reconstructions, and denoising improved the image quality to the point where the 80 kV images alone were considered to be of diagnostic quality. Conclusions: The results demonstrate that bilateral filtering incorporating a CT noise model can achieve a significantly better noise-resolution trade

  14. Evaluation of exposure dose reduction in multislice CT coronary angiography (MS-CTA) with prospective ECG-gated helical scan

    NASA Astrophysics Data System (ADS)

    Ota, Takamasa; Tsuyuki, Masaharu; Okumura, Miwa; Sano, Tomonari; Kondo, Takeshi; Takase, Shinichi

    2008-03-01

    A novel low-dose ECG-gated helical scan method to investigate coronary artery diseases was developed. This method uses a high pitch for scanning (based on the patient's heart rate) and X-rays are generated only during the optimal cardiac phases. The dose reduction was obtained using a two-level approach: 1) To use a 64-slice CT scanner (Aquilion, Toshiba, Otawara, Tochigi, Japan) with a scan speed of 0.35 s/rot. to helically scan the heart at a high pitch based on the patient's heart rate. By changing the pitch from the conventional 0.175 to 0.271 for a heart rate of 60 bpm, the exposure dose was reduced to 65%. 2) To employ tube current gating that predicts the timing of optimal cardiac phases from the previous cardiac cycle and generates X-rays only during the required cardiac phases. The combination of high speed scanning with a high pitch and appropriate X-ray generation only in the cardiac phases from 60% to 90% allows the exposure dose to be reduced to 5.6 mSv for patients with a heart rate lower than 65 bpm. This is a dose reduction of approximately 70% compared to the conventional scanning method recommended by the manufacturer when segmental reconstruction is considered. This low-dose protocol seamlessly allows for wide scan ranges (e.g., aortic dissection) with the benefits of ECG-gated helical scanning: smooth continuity for longitudinal direction and utilization of data from all cardiac cycles.

  15. Method for simulating dose reduction in digital mammography using the Anscombe transformation

    PubMed Central

    Borges, Lucas R.; de Oliveira, Helder C. R.; Nunes, Polyana F.; Bakic, Predrag R.; Maidment, Andrew D. A.; Vieira, Marcelo A. C.

    2016-01-01

    Purpose: This work proposes an accurate method for simulating dose reduction in digital mammography starting from a clinical image acquired with a standard dose. Methods: The method developed in this work consists of scaling a mammogram acquired at the standard radiation dose and adding signal-dependent noise. The algorithm accounts for specific issues relevant in digital mammography images, such as anisotropic noise, spatial variations in pixel gain, and the effect of dose reduction on the detective quantum efficiency. The scaling process takes into account the linearity of the system and the offset of the detector elements. The inserted noise is obtained by acquiring images of a flat-field phantom at the standard radiation dose and at the simulated dose. Using the Anscombe transformation, a relationship is created between the calculated noise mask and the scaled image, resulting in a clinical mammogram with the same noise and gray level characteristics as an image acquired at the lower-radiation dose. Results: The performance of the proposed algorithm was validated using real images acquired with an anthropomorphic breast phantom at four different doses, with five exposures for each dose and 256 nonoverlapping ROIs extracted from each image and with uniform images. The authors simulated lower-dose images and compared these with the real images. The authors evaluated the similarity between the normalized noise power spectrum (NNPS) and power spectrum (PS) of simulated images and real images acquired with the same dose. The maximum relative error was less than 2.5% for every ROI. The added noise was also evaluated by measuring the local variance in the real and simulated images. The relative average error for the local variance was smaller than 1%. Conclusions: A new method is proposed for simulating dose reduction in clinical mammograms. In this method, the dependency between image noise and image signal is addressed using a novel application of the Anscombe

  16. VirtualDose: a software for reporting organ doses from CT for adult and pediatric patients.

    PubMed

    Ding, Aiping; Gao, Yiming; Liu, Haikuan; Caracappa, Peter F; Long, Daniel J; Bolch, Wesley E; Liu, Bob; Xu, X George

    2015-07-21

    This paper describes the development and testing of VirtualDose--a software for reporting organ doses for adult and pediatric patients who undergo x-ray computed tomography (CT) examinations. The software is based on a comprehensive database of organ doses derived from Monte Carlo (MC) simulations involving a library of 25 anatomically realistic phantoms that represent patients of different ages, body sizes, body masses, and pregnant stages. Models of GE Lightspeed Pro 16 and Siemens SOMATOM Sensation 16 scanners were carefully validated for use in MC dose calculations. The software framework is designed with the 'software as a service (SaaS)' delivery concept under which multiple clients can access the web-based interface simultaneously from any computer without having to install software locally. The RESTful web service API also allows a third-party picture archiving and communication system software package to seamlessly integrate with VirtualDose's functions. Software testing showed that VirtualDose was compatible with numerous operating systems including Windows, Linux, Apple OS X, and mobile and portable devices. The organ doses from VirtualDose were compared against those reported by CT-Expo and ImPACT-two dosimetry tools that were based on the stylized pediatric and adult patient models that were known to be anatomically simple. The organ doses reported by VirtualDose differed from those reported by CT-Expo and ImPACT by as much as 300% in some of the patient models. These results confirm the conclusion from past studies that differences in anatomical realism offered by stylized and voxel phantoms have caused significant discrepancies in CT dose estimations.

  17. Working Face-to-Face for Pediatric CT Dose Reduction: A Community Toolkit

    PubMed Central

    Armao, Diane; Hartman, Terry; Shea, Christopher M.; Sams, Cassandra; Fordham, Lynn Ansley; Smith, J. Keith

    2016-01-01

    Although children are especially vulnerable to the health risks of ionizing radiation, approximately 8 million CTs are performed on children in the USA. Widespread dose variation is common, particularly in non-pediatric focused facilities. In this article we present our rationale and hands-on approach in developing and refining a toolkit aimed at helping a community hospital with pediatric CT dose reduction. PMID:27942250

  18. IMRT in a Pregnant Patient: How to Reduce the Fetal Dose?

    SciTech Connect

    Josipovic, Mirjana Nystroem, Hakan; Kjaer-Kristoffersen, Flemming

    2009-01-01

    The purpose of our study was to find a solution for fetal dose reduction during head-and-neck intensity modulated radiation therapy (IMRT) of a pregnant patient. The first step was optimization of the IMRT treatment plan with as few monitor units (MUs) as possible, while maintaining an acceptable dose distribution. The peripheral dose originating from the final IMRT plan was measured at distances reaching from the most proximal to the most distal fetal position, along the accelerator's longitudinal axis, using an anthropomorphic phantom extended with water-equivalent plastic. The measured peripheral dose was divided into leakage, and internal and collimator scatter, to find the degree to which each component influences the peripheral dose to build an appropriate shield. Collimator scatter was the greatest contributor to the peripheral dose throughout the range of the growing fetus. A shield was built and placed beneath the accelerator head, extending caudally from the field edge, to function as an extra collimator jaw. This shield reduced the fetal dose by a factor of 3.5. The peripheral dose components were also measured for simple rectangular fields and also here the collimator scatter was the greatest contributor to the peripheral dose. Therefore, the shielding used for the IMRT treatment of our patient could also be used when shielding in conventional radiotherapy. It is important for a radiation therapy department to be prepared for treatment of a pregnant patient to shield the fetus efficiently.

  19. Utilisation of PACS to monitor patient CT doses.

    PubMed

    AlSuwaidi, J S; Bayoumi, M; Al Shibli, N; Sulaiman, H; Urrahman, T; AlYarah, M

    2011-09-01

    In the past 5 y, the number of computed tomography (CT) studies has doubled at Dubai Health Authority hospitals. This situation, along with patient's overdoses reported internationally, has prompted action to establish a system to manage patient doses incurred due to medical imaging practices. In this work, the authors aim to homogenise dose reporting to monitor radiation dose levels and facilitate the establishment of local and national dose reference levels. The two hospitals enrolled in this study are equipped with three CT systems (two 4 slices and one 64 slices). Through the Picture Archive and Communication Systems (PACS) tracking system, it is mandatory to fill CT patient doses in radiology information system (RIS). Dose length product (mGy cm) was recorded for 2502 adult and 178 paediatric patients. All patients' dosimetry data were collected from the RIS by Cogonos statistical software. The PACS data were reviewed to exclude incomplete data. Average and range of effective doses for adult and paediatric patients were calculated using an appropriate weighting factor. Individual accumulated effective doses for adult and paediatric patients were calculated for 4s-scanner-1 only. Adult average effective doses for the head (1482 exams) were 1.23 ± 0.58, 2.84 ± 0.83 and 2.98 ± 1.103 mSv, the chest (545 exams) were 5.39 ± 1.63, 21.85 ± 5.63 and 18.19 ± 3.22 mSv and for the abdomen and pelvis (1183 exams) were 10.85 ± 4.26, 25.66 ± 8.83 and 26.46 ± 13.75 mSv for 4s-scanner-1, 4s-scanner-2 and 64 s, respectively. The paediatric average effective dose for the head (127 exams) was 1.77 ± 0.82 mSv, for the chest (22 exams) was 3.3 ± 1.29 mSv and for the abdomen and pelvis (27 exams) was 6.16 ± 2.64 mSv. Results of individual accumulated effective doses for adult and paediatric patients were presented. PACS dose reporting facilitated dosimetry clinical auditing. Effective doses obtained in this work demonstrated that the results of one scanner were within

  20. Patient doses from hybrid SPECT-CT procedures.

    PubMed

    Avramova-Cholakova, S; Dimcheva, M; Petrova, E; Garcheva, M; Dimitrova, M; Palashev, Y; Vassileva, J

    2015-07-01

    The aim of this work is to estimate patient doses from hybrid single-photon emission computed tomography (SPECT) and computed tomography (CT) procedures. The study involved all four SPECT-CT systems in Bulgaria. Effective dose was estimated for about 100 patients per system. Ten types of examinations were considered, representing all diagnostic procedures performed in the SPECT-CT systems. Effective doses from the SPECT component were calculated applying the ICRP 53 and ICRP 80 conversion coefficients. Computed tomography dose index and dose length product were retrospectively obtained from the archives of the systems, and effective doses from the CT component were calculated with CT-Expo software. Parallel estimation of CT component contribution with the National Radiological Protection Board (NRPB) conversion coefficients was performed where applicable. Large variations were found in the current practice of SPECT-CT imaging. Optimisation actions and diagnostic reference levels were proposed.

  1. Automatic computed tomography patient dose calculation using DICOM header metadata.

    PubMed

    Jahnen, A; Kohler, S; Hermen, J; Tack, D; Back, C

    2011-09-01

    The present work describes a method that calculates the patient dose values in computed tomography (CT) based on metadata contained in DICOM images in support of patient dose studies. The DICOM metadata is preprocessed to extract necessary calculation parameters. Vendor-specific DICOM header information is harmonized using vendor translation tables and unavailable DICOM tags can be completed with a graphical user interface. CT-Expo, an MS Excel application for calculating the radiation dose, is used to calculate the patient doses. All relevant data and calculation results are stored for further analysis in a relational database. Final results are compiled by utilizing data mining tools. This solution was successfully used for the 2009 CT dose study in Luxembourg. National diagnostic reference levels for standard examinations were calculated based on each of the countries' hospitals. The benefits using this new automatic system saved time as well as resources during the data acquisition and the evaluation when compared with earlier questionnaire-based surveys.

  2. Patient release criteria for low dose rate brachytherapy implants.

    PubMed

    Boyce, Dale E; Sheetz, Michael A

    2013-04-01

    A lack of consensus regarding a model governing the release of patients following sealed source brachytherapy has led to a set of patient release policies that vary from institution to institution. The U.S. Nuclear Regulatory Commission has issued regulatory guidance on patient release in NUREG 1556, Volume 9, Rev. 2, Appendix U, which allows calculation of release limits following implant brachytherapy. While the formalism presented in NUREG is meaningful for the calculation of release limits in the context of relatively high energy gamma emitters, it does not estimate accurately the effective dose equivalent for the common low dose rate brachytherapy sources Cs, I, and Pd. NUREG 1556 states that patient release may be based on patient-specific calculations as long as the calculation is documented. This work is intended to provide a format for patient-specific calculations to be used for the consideration of patients' release following the implantation of certain low dose rate brachytherapy isotopes.

  3. Successful Within-patient Dose Escalation of Olipudase Alfa in Acid Sphingomyelinase Deficiency

    PubMed Central

    Wasserstein, Melissa P.; Jones, Simon A.; Soran, Handrean; Diaz, George A.; Lippa, Natalie; Thurberg, Beth L.; Culm-Merdek, Kerry; Shamiyeh, Elias; Inguilizian, Haig; Cox, Gerald F.; Puga, Ana Cristina

    2015-01-01

    Background Olipudase alfa, a recombinant human acid sphingomyelinase (rhASM), is an investigational enzyme replacement therapy (ERT) for patients with ASM deficiency [ASMD; Niemann-Pick Disease (NPD) A and B]. This open-label phase 1b study assessed the safety and tolerability of olipudase alfa using within-patient dose escalation to gradually debulk accumulated sphingomyelin and mitigate the rapid production of metabolites, which can be toxic. Secondary objectives were pharmacokinetics, pharmacodynamics, and exploratory efficacy. Methods Five adults with nonneuronopathic ASMD (NPD B) received escalating doses (0.1 to 3.0 mg/kg) of olipudase alfa intravenously every 2 weeks for 26 weeks. Results All patients successfully reached 3.0 mg/kg without serious or severe adverse events. One patient repeated a dose (2.0 mg/kg) and another had a temporary dose reduction (1.0 to 0.6 mg/kg). Most adverse events (97%) were mild and all resolved without sequelae. The most common adverse events were headache, arthralgia, nausea and abdominal pain. Two patients experienced single acute phase reactions. No patient developed hypersensitivity or anti-olipudase alfa antibodies. The mean circulating half-life of olipudase alfa ranged from 20.9 to 23.4 hours across doses without accumulation. Ceramide, a sphingomyelin catabolite, rose transiently in plasma after each dose, but decreased over time. Reductions in sphingomyelin storage, spleen and liver volumes, and serum chitotriosidase activity, as well as improvements in infiltrative lung disease, lipid profiles, platelet counts, and quality of life assessments, were observed. Conclusions This study provides proof-of-concept for the safety and efficacy of within-patient dose escalation of olipudase alfa in patients with nonneuronopathic ASMD. PMID:26049896

  4. A comparison of mantle versus involved-field radiotherapy for Hodgkin's lymphoma: reduction in normal tissue dose and second cancer risk

    PubMed Central

    Koh, Eng-Siew; Tran, Tu Huan; Heydarian, Mostafa; Sachs, Rainer K; Tsang, Richard W; Brenner, David J; Pintilie, Melania; Xu, Tony; Chung, June; Paul, Narinder; Hodgson, David C

    2007-01-01

    Background Hodgkin's lymphoma (HL) survivors who undergo radiotherapy experience increased risks of second cancers (SC) and cardiac sequelae. To reduce such risks, extended-field radiotherapy (RT) for HL has largely been replaced by involved field radiotherapy (IFRT). While it has generally been assumed that IFRT will reduce SC risks, there are few data that quantify the reduction in dose to normal tissues associated with modern RT practice for patients with mediastinal HL, and no estimates of the expected reduction in SC risk. Methods Organ-specific dose-volume histograms (DVH) were generated for 41 patients receiving 35 Gy mantle RT, 35 Gy IFRT, or 20 Gy IFRT, and integrated organ mean doses were compared for the three protocols. Organ-specific SC risk estimates were estimated using a dosimetric risk-modeling approach, analyzing DVH data with quantitative, mechanistic models of radiation-induced cancer. Results Dose reductions resulted in corresponding reductions in predicted excess relative risks (ERR) for SC induction. Moving from 35 Gy mantle RT to 35 Gy IFRT reduces predicted ERR for female breast and lung cancer by approximately 65%, and for male lung cancer by approximately 35%; moving from 35 Gy IFRT to 20 Gy IFRT reduces predicted ERRs approximately 40% more. The median reduction in integral dose to the whole heart with the transition to 35 Gy IFRT was 35%, with a smaller (2%) reduction in dose to proximal coronary arteries. There was no significant reduction in thyroid dose. Conclusion The significant decreases estimated for radiation-induced SC risks associated with modern IFRT provide strong support for the use of IFRT to reduce the late effects of treatment. The approach employed here can provide new insight into the risks associated with contemporary IFRT for HL, and may facilitate the counseling of patients regarding the risks associated with this treatment. PMID:17362522

  5. Effects of Low-Dose Mindfulness-Based Stress Reduction (MBSR-ld) on Working Adults

    ERIC Educational Resources Information Center

    Klatt, Maryanna D.; Buckworth, Janet; Malarkey, William B.

    2009-01-01

    Mindfulness-based stress reduction (MBSR) has produced behavioral, psychological, and physiological benefits, but these programs typically require a substantial time commitment from the participants. This study assessed the effects of a shortened (low-dose [ld]) work-site MBSR intervention (MBSR-ld) on indicators of stress in healthy working…

  6. VirtualDose: a software for reporting organ doses from CT for adult and pediatric patients

    NASA Astrophysics Data System (ADS)

    Ding, Aiping; Gao, Yiming; Liu, Haikuan; Caracappa, Peter F.; Long, Daniel J.; Bolch, Wesley E.; Liu, Bob; Xu, X. George

    2015-07-01

    This paper describes the development and testing of VirtualDose—a software for reporting organ doses for adult and pediatric patients who undergo x-ray computed tomography (CT) examinations. The software is based on a comprehensive database of organ doses derived from Monte Carlo (MC) simulations involving a library of 25 anatomically realistic phantoms that represent patients of different ages, body sizes, body masses, and pregnant stages. Models of GE Lightspeed Pro 16 and Siemens SOMATOM Sensation 16 scanners were carefully validated for use in MC dose calculations. The software framework is designed with the ‘software as a service (SaaS)’ delivery concept under which multiple clients can access the web-based interface simultaneously from any computer without having to install software locally. The RESTful web service API also allows a third-party picture archiving and communication system software package to seamlessly integrate with VirtualDose’s functions. Software testing showed that VirtualDose was compatible with numerous operating systems including Windows, Linux, Apple OS X, and mobile and portable devices. The organ doses from VirtualDose were compared against those reported by CT-Expo and ImPACT—two dosimetry tools that were based on the stylized pediatric and adult patient models that were known to be anatomically simple. The organ doses reported by VirtualDose differed from those reported by CT-Expo and ImPACT by as much as 300% in some of the patient models. These results confirm the conclusion from past studies that differences in anatomical realism offered by stylized and voxel phantoms have caused significant discrepancies in CT dose estimations.

  7. Organ doses to adult patients for chest CT

    SciTech Connect

    Huda, Walter; Sterzik, Alexander; Tipnis, Sameer; Schoepf, U. Joseph

    2010-02-15

    Purpose: The goal of this study was to estimate organ doses for chest CT examinations using volume computed tomography dose index (CTDI{sub vol}) data as well as accounting for patient weight. Methods: A CT dosimetry spreadsheet (ImPACT CT patient dosimetry calculator) was used to compute organ doses for a 70 kg patient undergoing chest CT examinations, as well as volume computed tomography dose index (CTDI{sub vol}) in a body CT dosimetry phantom at the same CT technique factors. Ratios of organ dose to CTDI{sub vol} (f{sub organ}) were generated as a function of anatomical location in the chest for the breasts, lungs, stomach, red bone marrow, liver, thyroid, liver, and thymus. Values of f{sub organ} were obtained for x-ray tube voltages ranging from 80 to 140 kV for 1, 4, 16, and 64 slice CT scanners from two vendors. For constant CT techniques, we computed ratios of dose in water phantoms of differing diameter. By modeling patients of different weights as equivalent water cylinders of different diameters, we generated factors that permit the estimation of the organ doses in patients weighing between 50 and 100 kg who undergo chest CT examinations relative to the corresponding organ doses received by a 70 kg adult. Results: For a 32 cm long CT scan encompassing the complete lungs, values of f{sub organ} ranged from 1.7 (thymus) to 0.3 (stomach). Organs that are directly in the x-ray beam, and are completely irradiated, generally had f{sub organ} values well above 1 (i.e., breast, lung, heart, and thymus). Organs that are not completely irradiated in a total chest CT scan generally had f{sub organ} values that are less than 1 (e.g., red bone marrow, liver, and stomach). Increasing the x-ray tube voltage from 80 to 140 kV resulted in modest increases in f{sub organ} for the heart (9%) and thymus (8%), but resulted in larger increases for the breast (19%) and red bone marrow (21%). Adult patient chests have been modeled by water cylinders with diameters between

  8. Characterization of adaptive statistical iterative reconstruction algorithm for dose reduction in CT: A pediatric oncology perspective

    SciTech Connect

    Brady, S. L.; Yee, B. S.; Kaufman, R. A.

    2012-09-15

    Purpose: This study demonstrates a means of implementing an adaptive statistical iterative reconstruction (ASiR Trade-Mark-Sign ) technique for dose reduction in computed tomography (CT) while maintaining similar noise levels in the reconstructed image. The effects of image quality and noise texture were assessed at all implementation levels of ASiR Trade-Mark-Sign . Empirically derived dose reduction limits were established for ASiR Trade-Mark-Sign for imaging of the trunk for a pediatric oncology population ranging from 1 yr old through adolescence/adulthood. Methods: Image quality was assessed using metrics established by the American College of Radiology (ACR) CT accreditation program. Each image quality metric was tested using the ACR CT phantom with 0%-100% ASiR Trade-Mark-Sign blended with filtered back projection (FBP) reconstructed images. Additionally, the noise power spectrum (NPS) was calculated for three common reconstruction filters of the trunk. The empirically derived limitations on ASiR Trade-Mark-Sign implementation for dose reduction were assessed using (1, 5, 10) yr old and adolescent/adult anthropomorphic phantoms. To assess dose reduction limits, the phantoms were scanned in increments of increased noise index (decrementing mA using automatic tube current modulation) balanced with ASiR Trade-Mark-Sign reconstruction to maintain noise equivalence of the 0% ASiR Trade-Mark-Sign image. Results: The ASiR Trade-Mark-Sign algorithm did not produce any unfavorable effects on image quality as assessed by ACR criteria. Conversely, low-contrast resolution was found to improve due to the reduction of noise in the reconstructed images. NPS calculations demonstrated that images with lower frequency noise had lower noise variance and coarser graininess at progressively higher percentages of ASiR Trade-Mark-Sign reconstruction; and in spite of the similar magnitudes of noise, the image reconstructed with 50% or more ASiR Trade-Mark-Sign presented a more

  9. Collection of DICOM RDSR (Digital Imaging and Communication in Medicine, Radiation Dose Structured Report) Information Aimed at Reducing Patient Exposure Dose.

    PubMed

    Morota, Koichi; Moritake, Takashi; Sun, Lue; Ishihara, Takahiro; Kuma, Natsuyo; Murata, Satomi; Yamada, Takahiro; Okazaki, Ryuji

    2016-01-01

    The recent progress in angiography technology bestows benefits on patients for minimally invasive than surgery, while there has been an increase in the number of cases involving stochastic effects, such as radiation dermatitis, resulting from upgrading of the procedure because of an extension of the time for fluoroscopy and the number of shots. Recent CT equipment saves the dose data along with image data about the information management for patient exposure dose, which is used for management of individual cumulative dose and the presumed effective dose, using digital imaging and communication in medicine (DICOM). We extracted detailed information about shooting conditions and dose from the DICOM radiation dose structured report (DICOM RDSR) in the angiography area, and evaluated the trend of patient exposure dose in each procedure. As a result, we found that cases exceeding 3 Gy which needed observation in the head region were 16.7% and in the heart region were 27.3%. We also found that angiography had a higher dose of shooting than did fluoroscopy, and that the diagnosis and treatment with tumor involvement required a exposure dose than did vascular lesion. In this paper, we review the shooting conditions as a root of DICOM RDSR information and consider the possibility of planning for further reduction of the exposure dose.

  10. Survey of patient dose in computed tomography in Syria 2009.

    PubMed

    Kharita, M H; Khazzam, S

    2010-09-01

    The radiation doses to patient in computed tomography (CT) in Syria have been investigated and compared with similar studies in different countries. This work surveyed 30 CT scanners from six different manufacturers distributed all over Syria. Some of the results in this paper were part of a project launched by the International Atomic Energy Agency in different regions of the world covering Asia, Africa and Eastern Europe. The dose quantities covered are CT dose index (CTDI(w)), dose-length product (DLP), effective dose (E) and collective dose. It was found that most CTDI(w) and DLP values were similar to the European reference levels and in line with the results of similar surveys in the world. The results were in good agreement with the UNSCEAR Report 2007. This study concluded a recommendation for national diagnostic reference level for the most common CT protocols in Syria. The results can be used as a base for future optimisation studies in the country.

  11. [Patient dose optimization in pediatric computerized tomography].

    PubMed

    Verdun, F R; Schnyder, P; Gutièrrez, D; Gudinchet, F

    2006-07-12

    The development of CT applications might become a public health problem if no effort is made on the justification and the optimisation of the examinations. This paper presents some hints to assure that the risk-benefit compromise remains in favour of the patient, especially when one deals with the examinations of young patients. In this context a particular attention has to be made on the justification of the examination. When performing the acquisition one needs to optimise the extension of the volume investigated together with the number of acquisition sequences used. Finally, the use of automatic exposure systems, now available on all the units, and the use of the Diagnostic Reference Levels (DRL) should allow help radiologists to control the exposure of their patients.

  12. Very low-dose lenalidomide therapy for elderly multiple myeloma patients.

    PubMed

    Minagawa, Kentaro; Kawano, Hiroki; Suzuki, Takuma; Inagaki, Tadahiro; Kishi, Minoru; Hirata, Tamaki; Kimura, Sachiko; Takechi, Miho; Koide, Toru; Iwai, Masahide; Katayama, Yoshio; Matsui, Toshimitsu

    2013-05-01

    Lenalidomide treatment for refractory or relapsed multiple myeloma in elderly patients may be feasible in an outpatient setting. However, difficulties have been associated with the management of adverse effects. Therefore, a dose reduction in lenalidomide has been recommended in some cases. In this report, we encountered the successful treatment of myeloma in 6 elderly patients (aged above 70 years) with very low-dose lenalidomide (5 mg daily). Four patients exhibited more than a partial response with an 8.6 months median follow-up period, which was comparable with previous findings. The major adverse effect observed was infection, which occurred during the first several cycles. Others were less toxic, especially the absence of grade 3/4 toxicities for hematological adverse effects.Although a dose reduction in lenalidomide therapy for elderly patients is controversial, a very low dose could be safe and effective. Our group is currently conducting a multi-center prospective trial to evaluate the efficacy of low-dose lenalidomide therapy.

  13. Pharmacokinetics and Pharmacodynamics with Extended Dosing of CC-486 in Patients with Hematologic Malignancies

    PubMed Central

    Garcia-Manero, Guillermo; Cogle, Christopher R.; Gore, Steven D.; Hetzer, Joel; Kumar, Keshava; Skikne, Barry; MacBeth, Kyle J.

    2015-01-01

    CC-486 (oral azacitidine) is an epigenetic modifier in development for patients with myelodysplastic syndromes and acute myeloid leukemia. In part 1 of this two-part study, a 7-day CC-486 dosing schedule showed clinical activity, was generally well tolerated, and reduced DNA methylation. Extending dosing of CC-486 beyond 7 days would increase duration of azacitidine exposure. We hypothesized that extended dosing would therefore provide more sustained epigenetic activity. Reported here are the pharmacokinetic (PK) and pharmacodynamic (PD) profiles of CC-486 extended dosing schedules in patients with myelodysplastic syndromes (MDS), chronic myelomonocytic leukemia (CMML) or acute myeloid leukemia (AML) from part 2 of this study. PK and/or PD data were available for 59 patients who were sequentially assigned to 1 of 4 extended CC-486 dosing schedules: 300mg once-daily or 200mg twice-daily for 14 or 21 days per 28-day cycle. Both 300mg once-daily schedules and the 200mg twice-daily 21-day schedule significantly (all P < .05) reduced global DNA methylation in whole blood at all measured time points (days 15, 22, and 28 of the treatment cycle), with sustained hypomethylation at cycle end compared with baseline. CC-486 exposures and reduced DNA methylation were significantly correlated. Patients who had a hematologic response had significantly greater methylation reductions than non-responding patients. These data demonstrate that extended dosing of CC-486 sustains epigenetic effects through the treatment cycle. Trial Registration ClinicalTrials.gov NCT00528983 PMID:26296092

  14. Impact of sweating on equivalent dose of patients treated with 131Iiodine

    PubMed Central

    Haghighatafshar, Mahdi; Banani, Aida; Gheisari, Farshid; Alikhani, Mohammad

    2016-01-01

    Background: Radioiodine therapy is used for the treatment of patients with differentiated thyroid cancer (DTC) who undergo total thyroidectomy. After radioiodine administration, regulations require to quarantine these patients until their retained activity reduces to <33 mCi. Some of the injected radioiodine is excreted by perspiration which helps dose reduction so that performing the activities which stimulate sweating such as exercise may shorten the time of dose reduction. To the best of our knowledge, this is the first study in the literature that has evaluated the impact of specific exercise program on the ambient equivalent dose of 131I gamma rays. Materials and Methods: Patients with DTC without metastasis who had undergone total thyroidectomy and were treated with radioiodine were included in this study. 30 patients were chosen among patients who were able to exercise, did not have renal failure, and did not use diuretics. Patients were divided into two control and intervention groups. Intervention group members walked on treadmills under a specific program, in 3 time intervals. The control group did not have any specific activity. Immediately after each exercise process, both groups took a shower, and their doses were measured by a survey dosimeter. Results: It was revealed that there was a significant difference between mean values before and after each exercise time. The calculated P value which evaluates the overall impact was 0.939 which revealed that there was no significant difference between total ambient equivalent dose reductions of both groups. Conclusion: According to the study, it may conclude that sweating is an effective alternative way for radioiodine excretion, and if sweating is accompanied with well-hydrated status they may have synergism effect to shorten quarantine period. This could be an important consideration in patients which over-hydration is intolerable especially those with cardiac, liver, or renal problems. PMID:27385884

  15. A CONCEPTUAL FRAMEWORK FOR MANAGING RADIATION DOSE TO PATIENTS IN DIAGNOSTIC RADIOLOGY USING REFERENCE DOSE LEVELS.

    PubMed

    Almén, Anja; Båth, Magnus

    2016-06-01

    The overall aim of the present work was to develop a conceptual framework for managing radiation dose in diagnostic radiology with the intention to support optimisation. An optimisation process was first derived. The framework for managing radiation dose, based on the derived optimisation process, was then outlined. The outset of the optimisation process is four stages: providing equipment, establishing methodology, performing examinations and ensuring quality. The optimisation process comprises a series of activities and actions at these stages. The current system of diagnostic reference levels is an activity in the last stage, ensuring quality. The system becomes a reactive activity only to a certain extent engaging the core activity in the radiology department, performing examinations. Three reference dose levels-possible, expected and established-were assigned to the three stages in the optimisation process, excluding ensuring quality. A reasonably achievable dose range is also derived, indicating an acceptable deviation from the established dose level. A reasonable radiation dose for a single patient is within this range. The suggested framework for managing radiation dose should be regarded as one part of the optimisation process. The optimisation process constitutes a variety of complementary activities, where managing radiation dose is only one part. This emphasises the need to take a holistic approach integrating the optimisation process in different clinical activities.

  16. Paediatric x-ray radiation dose reduction and image quality analysis.

    PubMed

    Martin, L; Ruddlesden, R; Makepeace, C; Robinson, L; Mistry, T; Starritt, H

    2013-09-01

    Collaboration of multiple staff groups has resulted in significant reduction in the risk of radiation-induced cancer from radiographic x-ray exposure during childhood. In this study at an acute NHS hospital trust, a preliminary audit identified initial exposure factors. These were compared with European and UK guidance, leading to the introduction of new factors that were in compliance with European guidance on x-ray tube potentials. Image quality was assessed using standard anatomical criteria scoring, and visual grading characteristics analysis assessed the impact on image quality of changes in exposure factors. This analysis determined the acceptability of gradual radiation dose reduction below the European and UK guidance levels. Chest and pelvis exposures were optimised, achieving dose reduction for each age group, with 7%-55% decrease in critical organ dose. Clinicians confirmed diagnostic image quality throughout the iterative process. Analysis of images acquired with preliminary and final exposure factors indicated an average visual grading analysis result of 0.5, demonstrating equivalent image quality. The optimisation process and final radiation doses are reported for Carestream computed radiography to aid other hospitals in minimising radiation risks to children.

  17. Managing patient dose in multi-detector computed tomography(MDCT). ICRP Publication 102.

    PubMed

    Valentin, J

    2007-01-01

    Computed tomography (CT) technology has changed considerably in recent years with the introduction of increasing numbers of multiple detector arrays. There are several parameters specific to multi-detector computed tomography (MDCT) scanners that increase or decrease patient dose systematically compared to older single detector computed tomography (SDCT) scanners. This document briefly reviews the MDCT technology, radiation dose in MDCT, including differences from SDCT and factors that affect dose, radiation risks, and the responsibilities for patient dose management. The document recommends that users need to understand the relationship between patient dose and image quality and be aware that image quality in CT is often higher than that necessary for diagnostic confidence. Automatic exposure control (AEC) does not totally free the operator from selection of scan parameters, and awareness of individual systems is important. Scanning protocols cannot simply be transferred between scanners from different manufacturers and should be determined for each MDCT. If the image quality is appropriately specified by the user, and suited to the clinical task, there will be a reduction in patient dose for most patients. Understanding of some parameters is not intuitive and the selection of image quality parameter values in AEC systems is not straightforward. Examples of some clinical situation shave been included to demonstrate dose management, e.g. CT examinations of the chest, the heart for coronary calcium quantification and non-invasive coronary angiography, colonography, the urinary tract, children, pregnant patients, trauma cases, and CT guided interventions. CT is increasingly being used to replace conventional x-ray studies and it is important that patient dose is given careful consideration, particularly with repeated or multiple examinations.

  18. Monte Carlo calculation of patient organ doses from computed tomography.

    PubMed

    Oono, Takeshi; Araki, Fujio; Tsuduki, Shoya; Kawasaki, Keiichi

    2014-01-01

    In this study, we aimed to evaluate quantitatively the patient organ dose from computed tomography (CT) using Monte Carlo calculations. A multidetector CT unit (Aquilion 16, TOSHIBA Medical Systems) was modeled with the GMctdospp (IMPS, Germany) software based on the EGSnrc Monte Carlo code. The X-ray spectrum and the configuration of the bowtie filter for the Monte Carlo modeling were determined from the chamber measurements for the half-value layer (HVL) of aluminum and the dose profile (off-center ratio, OCR) in air. The calculated HVL and OCR were compared with measured values for body irradiation with 120 kVp. The Monte Carlo-calculated patient dose distribution was converted to the absorbed dose measured by a Farmer chamber with a (60)Co calibration factor at the center of a CT water phantom. The patient dose was evaluated from dose-volume histograms for the internal organs in the pelvis. The calculated Al HVL was in agreement within 0.3% with the measured value of 5.2 mm. The calculated dose profile in air matched the measured value within 5% in a range of 15 cm from the central axis. The mean doses for soft tissues were 23.5, 23.8, and 27.9 mGy for the prostate, rectum, and bladder, respectively, under exposure conditions of 120 kVp, 200 mA, a beam pitch of 0.938, and beam collimation of 32 mm. For bones of the femur and pelvis, the mean doses were 56.1 and 63.6 mGy, respectively. The doses for bone increased by up to 2-3 times that of soft tissue, corresponding to the ratio of their mass-energy absorption coefficients.

  19. Effective dose to patients from chest examinations with tomosynthesis.

    PubMed

    Båth, Magnus; Svalkvist, Angelica; von Wrangel, Alexa; Rismyhr-Olsson, Heidi; Cederblad, Ake

    2010-01-01

    Chest tomosynthesis, which refers to the principle of collecting low-dose projections of the chest at different angles and using these projections to reconstruct section images of the chest, is an imaging technique recently introduced to health care. The main purpose of the present work was to determine the average effective dose to patients from clinical use of chest tomosynthesis. Exposure data for two chest radiography laboratories with tomosynthesis option (Definium 8000 with VolumeRAD option, GE Healthcare, Chalfont St. Giles, UK) were registered for 20 patients with a weight between 60 and 80 kg (average weight of 70.2 kg). The recorded data were used in the Monte Carlo program PCXMC 2.0 (STUK-Radiation and Nuclear Safety Authority, Helsinki, Finland) to determine the average effective dose for each projection. The effective dose for the chest tomosynthesis examination, including a scout view and the tomosynthesis acquisition, was finally obtained by adding the effective doses from all projections. Using the weighting factors given in ICRP 103, the average effective dose for the examination was found to be 0.13 mSv, whereas the average effective dose for the conventional two-view chest radiography examination was 0.05 mSv. A conversion factor of 0.26 mSv Gy(-1) cm(-2) was found suitable for determining the effective dose from a VolumeRAD chest tomosynthesis examination from the total registered kerma-area product. In conclusion, the effective dose to a standard-sized patient (170 cm/70 kg) from a VolumeRAD chest tomosynthesis examination is ~2 % of an average chest CT and only two to three times the effective dose from the conventional two-view chest radiography examination.

  20. Effects of dose reduction on bone strength prediction using finite element analysis

    NASA Astrophysics Data System (ADS)

    Anitha, D.; Subburaj, Karupppasamy; Mei, Kai; Kopp, Felix K.; Foehr, Peter; Noel, Peter B.; Kirschke, Jan S.; Baum, Thomas

    2016-12-01

    This study aimed to evaluate the effect of dose reduction, by means of tube exposure reduction, on bone strength prediction from finite-element (FE) analysis. Fresh thoracic mid-vertebrae specimens (n = 11) were imaged, using multi-detector computed tomography (MDCT), at different intensities of X-ray tube exposures (80, 150, 220 and 500 mAs). Bone mineral density (BMD) was estimated from the mid-slice of each specimen from MDCT images. Differences in image quality and geometry of each specimen were measured. FE analysis was performed on all specimens to predict fracture load. Paired t-tests were used to compare the results obtained, using the highest CT dose (500 mAs) as reference. Dose reduction had no significant impact on FE-predicted fracture loads, with significant correlations obtained with reference to 500 mAs, for 80 mAs (R2  = 0.997, p < 0.001), 150 mAs (R2 = 0.998, p < 0.001) and 220 mAs (R2 = 0.987, p < 0.001). There were no significant differences in volume quantification between the different doses examined. CT imaging radiation dose could be reduced substantially to 64% with no impact on strength estimates obtained from FE analysis. Reduced CT dose will enable early diagnosis and advanced monitoring of osteoporosis and associated fracture risk.

  1. Effects of dose reduction on bone strength prediction using finite element analysis

    PubMed Central

    Anitha, D.; Subburaj, Karupppasamy; Mei, Kai; Kopp, Felix K.; Foehr, Peter; Noel, Peter B.; Kirschke, Jan S.; Baum, Thomas

    2016-01-01

    This study aimed to evaluate the effect of dose reduction, by means of tube exposure reduction, on bone strength prediction from finite-element (FE) analysis. Fresh thoracic mid-vertebrae specimens (n = 11) were imaged, using multi-detector computed tomography (MDCT), at different intensities of X-ray tube exposures (80, 150, 220 and 500 mAs). Bone mineral density (BMD) was estimated from the mid-slice of each specimen from MDCT images. Differences in image quality and geometry of each specimen were measured. FE analysis was performed on all specimens to predict fracture load. Paired t-tests were used to compare the results obtained, using the highest CT dose (500 mAs) as reference. Dose reduction had no significant impact on FE-predicted fracture loads, with significant correlations obtained with reference to 500 mAs, for 80 mAs (R2  = 0.997, p < 0.001), 150 mAs (R2 = 0.998, p < 0.001) and 220 mAs (R2 = 0.987, p < 0.001). There were no significant differences in volume quantification between the different doses examined. CT imaging radiation dose could be reduced substantially to 64% with no impact on strength estimates obtained from FE analysis. Reduced CT dose will enable early diagnosis and advanced monitoring of osteoporosis and associated fracture risk. PMID:27934902

  2. Multiple-dose amikacin kinetics in pediatric oncology patients.

    PubMed

    Kramer, W G; Cleary, T; Frankel, L S; Kohl, S; Pickering, L K

    1979-11-01

    Amikacin kinetics was studied in 8 pediatric oncology patients who received the drug by intravenous infusion over 30 or 60 min at a dose of 5 mg/kg every 6 or 8 hr. This regimen is recommended but, due to patient variability, patients should be monitored. Dosing intervals during 1 or 2 and 3 or 4 days of therapy were studied with serum samples collected before and at the end of the infusion and serially to the end of the dosing interval. The data appeared consistent with and were analyzed according to 1-compartment model. An equation describing serum concentration with time for the multiple-dose case was fit to each patient's multiple-interval data with nonlinear regression. Half-life averaged 1.2 hr. volume of distribution 0.24 l/kg, and total body clearance 109 ml/min/1.73 m2 or 2.51 ml/min/kg. The volume of distribution and the clearance are greater than reported for adults and probably account for the larger dose needed to achieve and maintain therapeutic levels. Although the total daily dose was greater than previously reported, there were no signs of toxicity, although therapuetic concentrations were maintained.

  3. A method to determine the planar dose distributions in patient undergone radiotherapy

    NASA Astrophysics Data System (ADS)

    Cilla, S.; Viola, P.; Augelli, B. G.; D'Onofrio, G.; Grimaldi, L.; Craus, M.; Digesù, C.; Deodato, F.; Macchia, G.; Morganti, A. G.; Fidanzio, A.; Azario, L.; Piermattei, A.

    2008-06-01

    A 2D-array equipped with 729 vented plane parallel ion-chambers has been calibrated as a portal dose detector for radiotherapy in vivo measurements. The array has been positioned by a radiographic film stand at 120 cm from the source orthogonal to the radiotherapy beam delivered with the gantry angle at 180°. The collision between the 2D-array and the patient's couch have been avoided. In this work, using the measurements of the portal detector, we present a method to reconstruct the dose variations in the patient treated with step and shoot intensity-modulated beams (IMRT) for head-neck tumours. For this treatment morphological changes often occur during the fractionated therapy. In a first step an in-house software supplied the comparison between the measured portal dose and the one computed by a commercial treatment planning system within the field of view of the computed tomography (CT) scanner. For each patient, the percentage Pγ of chambers, where the comparison is in agreement within a selected acceptance criteria, was determined 8 times. At the first radiotherapy fraction the γ-index analysis supplied Pγ values of about 95%, within acceptance criteria in terms of dose-difference, ΔD, and distance-agreement, Δd, that was equal to 5% and 4 mm, respectively. These acceptance criteria were taken into account for small errors in the patient's set-up reproducibility and for the accuracy of the portal dose calculated by the treatment planning system (TPS) in particular when the beam was attenuated by inhomogeneous tissues and the shape of the head-neck body contours were irregular. During the treatment, some patients showed a reduction of the Pγ below 90% because due to radiotherapy treatment there was a change of the patient's morphology. In a second step a method, based on dosimetric measurements that used standard phantoms, supplied the percentage dose variations in a coronal plane of the patient using the percentage dose variations measured by the 2D

  4. Local anesthesia in reduction mastoplasty for out-patient surgery.

    PubMed

    Mottura, A A

    1992-01-01

    To perform a breast reduction under local anesthesia we need a large amount of anesthetic with lasting effects. For this I use a solution of 25 cc of lidocaine, 25 cc of bupivacaine, and 1 cc of epinephrine in 350 cc of saline solution. The bupivacaine allows a 4-6-hour operation. Once the breast is infiltrated, a great amount of anesthetic is lost in the incision, in the dissection, and in the resected tissue. Thus, a low dose remains subcutaneously to be metabolized by the liver. The serum lidocaine levels are low during these operations, as demonstrated by fluorescence polarization immunoassay. Under analgesic sedation the submammary sulcus and the retroglandular space are infiltrated, blocking the perforants of the intercostal nerves, under the areola, beneath the skin where the incision is made and where the areola is placed. This procedure has been applied to many techniques of breast reduction by modifying the infiltration under the incision lines. For hypertrophy up to 1000 g, 200-300 cc of anesthetic solution is used for both breasts at one stage, while for gigantomastia, about 400 cc of anesthetic is used, infiltrating and reducing one after the other. As the blood loss is minimal and the recovery very fast, with an appropriate adhesive bandage and a "soutien," the patient could be discharged in the afternoon. Our experience includes 94 reduction mastoplasties with local anesthesia, and also 74 other mastoplasties with equally good results. There were no patient complaints and, in general, they felt very comfortable, awakening without pain or side effects.

  5. SU-F-18C-15: Model-Based Multiscale Noise Reduction On Low Dose Cone Beam Projection

    SciTech Connect

    Yao, W; Farr, J

    2014-06-15

    Purpose: To improve image quality of low dose cone beam CT for patient positioning in radiation therapy. Methods: In low dose cone beam CT (CBCT) imaging systems, Poisson process governs the randomness of photon fluence at x-ray source and the detector because of the independent binomial process of photon absorption in medium. On a CBCT projection, the variance of fluence consists of the variance of noiseless imaging structure and that of Poisson noise, which is proportional to the mean (noiseless) of the fluence at the detector. This requires multiscale filters to smoothen noise while keeping the structure information of the imaged object. We used a mathematical model of Poisson process to design multiscale filters and established the balance of noise correction and structure blurring. The algorithm was checked with low dose kilo-voltage CBCT projections acquired from a Varian OBI system. Results: From the investigation of low dose CBCT of a Catphan phantom and patients, it showed that our model-based multiscale technique could efficiently reduce noise and meanwhile keep the fine structure of the imaged object. After the image processing, the number of visible line pairs in Catphan phantom scanned with 4 ms pulse time was similar to that scanned with 32 ms, and soft tissue structure from simulated 4 ms patient head-and-neck images was also comparable with scanned 20 ms ones. Compared with fixed-scale technique, the image quality from multiscale one was improved. Conclusion: Use of projection-specific multiscale filters can reach better balance on noise reduction and structure information loss. The image quality of low dose CBCT can be improved by using multiscale filters.

  6. KERMA-based radiation dose management system for real-time patient dose measurement

    NASA Astrophysics Data System (ADS)

    Kim, Kyo-Tae; Heo, Ye-Ji; Oh, Kyung-Min; Nam, Sang-Hee; Kang, Sang-Sik; Park, Ji-Koon; Song, Yong-Keun; Park, Sung-Kwang

    2016-07-01

    Because systems that reduce radiation exposure during diagnostic procedures must be developed, significant time and financial resources have been invested in constructing radiation dose management systems. In the present study, the characteristics of an existing ionization-based system were compared to those of a system based on the kinetic energy released per unit mass (KERMA). Furthermore, the feasibility of using the KERMA-based system for patient radiation dose management was verified. The ionization-based system corrected the effects resulting from radiation parameter perturbations in general radiography whereas the KERMA-based system did not. Because of this difference, the KERMA-based radiation dose management system might overestimate the patient's radiation dose due to changes in the radiation conditions. Therefore, if a correction factor describing the correlation between the systems is applied to resolve this issue, then a radiation dose management system can be developed that will enable real-time measurement of the patient's radiation exposure and acquisition of diagnostic images.

  7. Dosing celecoxib in pediatric patients with juvenile rheumatoid arthritis.

    PubMed

    Krishnaswami, Sriram; Hutmacher, Matt M; Robbins, Jeffery L; Bello, Akintunde; West, Christine; Bloom, Bradley J

    2012-08-01

    The objective was to derive dosing recommendations for the use of celecoxib in patients with juvenile rheumatoid arthritis (JRA) using pharmacokinetic (PK) and exposure-response data. PK and efficacy data from a randomized, double-blind, 12-week study of celecoxib dosed at 3 and 6 mg/kg twice a day (bid) as an investigational suspension formulation in 152 JRA patients aged 2 to 17 years, PK data from 36 adult RA patients, and relative bioavailability data in healthy adults comparing suspension or capsule sprinkles with the commercial capsule were analyzed. Typical oral clearance (L/h) values were 40% and 24% lower in patients weighing 10 and 25 kg, respectively, compared with a 70-kg patient. Longitudinal, logistic pharmacodynamic models incorporating linear effects of dose/area under the plasma concentration-time curve (AUC) over 0 to 12 hours (AUC(0-12)) suggested that the percentage of responders increased with celecoxib exposure. Systemic exposures (AUC) were similar for the suspension, capsule sprinkles, and intact capsule. Administration of a 50-mg bid capsule (or sprinkles) for patients weighing 10 to 25 kg and 100 mg bid for patients >25 kg was predicted to yield similar exposures and response rates as those observed in the JRA trial. Doses and dosage forms not studied in the JRA trial were approved based on the results of this analysis.

  8. Low-dose midazolam sedation: an option for patients undergoing serial hepatic venous pressure measurements.

    PubMed

    Steinlauf, A F; Garcia-Tsao, G; Zakko, M F; Dickey, K; Gupta, T; Groszmann, R J

    1999-04-01

    The hepatic venous pressure gradient (HVPG) is becoming increasingly used clinically. It is useful in the differential diagnosis of portal hypertension and provides a prognostic index in cirrhotic patients. Performance of serial measurements has been shown to be useful in guiding pharmacological therapy of portal hypertension and variceal hemorrhage. The technique is safe to perform; however, many patients are anxious and reluctant to undergo serial measurements. The effects of sedatives on portal pressure measurements have not yet been defined. The objective of this study was to evaluate the effects of midazolam on the HVPG. Twenty patients with compensated cirrhosis were included in this prospective, double-blind study. The HVPG was determined by subtracting the free hepatic venous pressure (FHVP) from the wedged hepatic venous pressure (WHVP). Patients were randomized to receive either placebo, 0.02 mg/kg midazolam, or 0.03 mg/kg midazolam, administered intravenously over 3 minutes. Immediately after drug administration and every 3 minutes thereafter, for a total of 30 or 40 minutes, measurements were repeated. Three hours later, patients were asked to state whether the sedative affected their state of comfort/relaxation. The effects of both doses of midazolam on HVPG did not differ significantly from those of placebo. Furthermore, neither dose of midazolam induced significant changes in HVPG as compared with baseline values. However, higher-dose midazolam (0.03 mg/kg) was associated with significant reductions in FHVP from baseline and a tendency for a reduction in WHVP. Both doses significantly increased patient comfort and relaxation during the test. Midazolam, used at a dose of 0.02 mg/kg, is effective in increasing patient comfort and relaxation during hepatic venous pressure measurements, without significantly affecting pressures (HVPG, WHVP, or FHVP). It is therefore an acceptable option for patients undergoing serial hepatic venous pressure measurements.

  9. Development of CT scanner models for patient organ dose calculations using Monte Carlo methods

    NASA Astrophysics Data System (ADS)

    Gu, Jianwei

    There is a serious and growing concern about the CT dose delivered by diagnostic CT examinations or image-guided radiation therapy imaging procedures. To better understand and to accurately quantify radiation dose due to CT imaging, Monte Carlo based CT scanner models are needed. This dissertation describes the development, validation, and application of detailed CT scanner models including a GE LightSpeed 16 MDCT scanner and two image guided radiation therapy (IGRT) cone beam CT (CBCT) scanners, kV CBCT and MV CBCT. The modeling process considered the energy spectrum, beam geometry and movement, and bowtie filter (BTF). The methodology of validating the scanner models using reported CTDI values was also developed and implemented. Finally, the organ doses to different patients undergoing CT scan were obtained by integrating the CT scanner models with anatomically-realistic patient phantoms. The tube current modulation (TCM) technique was also investigated for dose reduction. It was found that for RPI-AM, thyroid, kidneys and thymus received largest dose of 13.05, 11.41 and 11.56 mGy/100 mAs from chest scan, abdomen-pelvis scan and CAP scan, respectively using 120 kVp protocols. For RPI-AF, thymus, small intestine and kidneys received largest dose of 10.28, 12.08 and 11.35 mGy/100 mAs from chest scan, abdomen-pelvis scan and CAP scan, respectively using 120 kVp protocols. The dose to the fetus of the 3 month pregnant patient phantom was 0.13 mGy/100 mAs and 0.57 mGy/100 mAs from the chest and kidney scan, respectively. For the chest scan of the 6 month patient phantom and the 9 month patient phantom, the fetal doses were 0.21 mGy/100 mAs and 0.26 mGy/100 mAs, respectively. For MDCT with TCM schemas, the fetal dose can be reduced with 14%-25%. To demonstrate the applicability of the method proposed in this dissertation for modeling the CT scanner, additional MDCT scanner was modeled and validated by using the measured CTDI values. These results demonstrated that the

  10. Analysis of patient CT dose data using virtualdose

    NASA Astrophysics Data System (ADS)

    Bennett, Richard

    X-ray computer tomography has many benefits to medical and research applications. Recently, over the last decade CT has had a large increase in usage in hospitals and medical diagnosis. In pediatric care, from 2000 to 2006, abdominal CT scans increased by 49 % and chest CT by 425 % in the emergency room (Broder 2007). Enormous amounts of effort have been performed across multiple academic and government groups to determine an accurate measure of organ dose to patients who undergo a CT scan due to the inherent risks with ionizing radiation. Considering these intrinsic risks, CT dose estimating software becomes a necessary tool that health care providers and radiologist must use to determine many metrics to base the risks versus rewards of having an x-ray CT scan. This thesis models the resultant organ dose as body mass increases for patients with all other related scan parameters fixed. In addition to this,this thesis compares a modern dose estimating software, VirtualDose CT to two other programs, CT-Expo and ImPACT CT. The comparison shows how the software's theoretical basis and the phantom they use to represent the human body affect the range of results in organ dose. CT-Expo and ImPACT CT dose estimating software uses a different model for anatomical representation of the organs in the human body and the results show how that approach dramatically changes the outcome. The results categorizes four datasets as compared to the three software types where the appropriate phantom was available. Modeling was done to simulate chest abdominal pelvis scans and whole body scans. Organ dose difference versus body mass index shows as body mass index (BMI) ranges from 23.5 kg/m 2 to 45 kg/m2 the amount of organ dose also trends a percent change from -4.58 to -176.19 %. Comparing organ dose difference with increasing x-ray tube potential from 120 kVp to 140 kVp the percent change in organ dose increases from 55 % to 65 % across all phantoms. In comparing VirtualDose to CT

  11. High-dose gallium-67 therapy in patients with relapsed acute leukaemia: a feasibility study.

    PubMed Central

    Jonkhoff, A. R.; Plaizier, M. A.; Ossenkoppele, G. J.; Teule, G. J.; Huijgens, P. C.

    1995-01-01

    Gallium-67 (67Ga) accumulates in malignant tissues via the transferrin receptor without need for a monoclonal antibody and emits cytotoxic low-energy electrons. In this study we investigated the feasibility, pharmacokinetics, toxicity and preliminary efficiency of high-dose 67Ga injected intravenously (i.v.) in patients with acute leukaemia not responding to conventional therapy. Twelve doses of 36-105 mCi of Gallium67 citrate were administered as a push injection to eight patients with resistant leukaemia in a pilot study. All five patients with acute myeloid leukaemia (AML) and three patients with acute lymphoblastic leukaemia (ALL) had resistant disease or resistant relapse. No (sub)acute toxicity was observed. Independent of the administered dose, whole-blood radioactivity levels 10 min after administration measured only 1.25 +/- 1.39 microCi ml-1, indicating a large volume of distribution. Urine excretion in the first 24 h ranged from 18% to 51.5% (median 29.5%) of the administered dose. Cellular uptake of 67Ga was less than in previous in vitro studies. Whole-body radiation dose was estimated to be 0.25 +/- 0.03 cGy mCi-1. Red marrow dose was estimated to be between 0.18 +/- 0.02 and 0.97 +/- 0.12 cGy mCi-1. One definite response was observed in an ALL patient with disappearance of skin lesions, normalisation of the enlarged spleen and profound leucopenia. Three other patients showed transient reductions in white blood cell counts without disappearance of blasts from the peripheral blood. We conclude that high-dose i.v. 67Ga can be safely administered but that the uptake of 67Ga in blast cells must increase to make 67Ga therapeutically useful in patients with relapsed leukaemia. Images Figure 2 PMID:8519674

  12. Data base on dose reduction research projects for nuclear power plants. Volume 5

    SciTech Connect

    Khan, T.A.; Yu, C.K.; Roecklein, A.K.

    1994-05-01

    This is the fifth volume in a series of reports that provide information on dose reduction research and health physics technology or nuclear power plants. The information is taken from two of several databases maintained by Brookhaven National Laboratory`s ALARA Center for the Nuclear Regulatory Commission. The research section of the report covers dose reduction projects that are in the experimental or developmental phase. It includes topics such as steam generator degradation, decontamination, robotics, improvements in reactor materials, and inspection techniques. The section on health physics technology discusses dose reduction efforts that are in place or in the process of being implemented at nuclear power plants. A total of 105 new or updated projects are described. All project abstracts from this report are available to nuclear industry professionals with access to a fax machine through the ACEFAX system or a computer with a modem and the proper communications software through the ACE system. Detailed descriptions of how to access all the databases electronically are in the appendices of the report.

  13. Radiation dose reduction in invasive cardiology by restriction to adequate instead of optimized picture quality.

    PubMed

    Kuon, Eberhard; Dorn, Christian; Schmitt, Moritz; Dahm, Johannes B

    2003-05-01

    In this study, the cinegraphic image intensifier entrance dose level for coronary angiography was changed in four steps from dose level A (0.041 microGy frame(-1)), allowing high contrast, but coarse mottled background, to level D (0.164 microGy frame(-1)), affording high transparency and sharpness. Using this new approach throughout the course of 404 consecutive cardiac catheterizations, we reduced patient radiation exposures down to 11 to 16% of currently typical values: i.e., mean dose area products of 5.97 Gy cm2 (n = 91), 6.73 (n = 113), 8.11 (n = 91), and 8.90 (n = 109); cinegraphic dose area products of 2.34, 3.64, 4.56, and 5.49; and cinegraphic dose area products frame(-1) of 13.3, 19.8, 27.0, and 30.2 mGy cm2, for levels A, B, C, and D, respectively. The number of cinegraphic frames ranged within 168 to 182 per case. Our results show that during catheterization interventionalists should vary image intensifier entrance dose levels in accordance with documented structure, angulation, and body mass index. With the exception of cases with special requirements, lower dose levels typically guarantee an adequate image quality.

  14. Investigation into the effects of lead shielding for fetal dose reduction in CT pulmonary angiography.

    PubMed

    Kennedy, E V; Iball, G R; Brettle, D S

    2007-08-01

    This work aims to determine whether lead shielding can be used to decrease the radiation dose to the fetus during CT scans for the diagnosis of pulmonary embolism during early stage pregnancy. An anthropomorphic phantom was modified to contain a 15 cc ionization chamber at the site of the uterus to enable fetal dose to be measured. The effects of a range of scan parameters, positioning of lead and thicknesses of lead were investigated. Fetal dose was lower with lower values of kV(p) and mAs. An increasing thickness of lead decreased the radiation dose to the uterus, as did increasing the proportion of the patient covered by the lead shielding. Fetal dose increased exponentially as the edge of the scan volume moved closer to the point of measurement. In no experiment was the dose to the fetus increased by the presence of the lead. It was found that the fetal radiation dose from a CT scan following a pulmonary embolism protocol can be effectively reduced by the use of lead shielding.

  15. MO-DE-204-02: Optimization of the Patient CT Dose in Europe.

    PubMed

    Tsapaki, V

    2016-06-01

    The main topic of the session is to show how dose optimization is being implemented in various regions of the world, including Europe, Australia, North America and other regions. A multi-national study conducted under International Atomic Energy Agency (IAEA) across more than 50 less resourced countries gave insight into patient radiation doses and safety practices in CT, mammography, radiography and interventional procedures, both for children and adults. An important outcome was the capability development on dose assessment and management. An overview of recent European projects related to CT radiation dose and optimization both to adults and children will be presented. Existing data on DRLs together with a European methodology proposed on establishing and using DRLs for paediatric radiodiagnostic imaging and interventional radiology practices will be shown. Compared with much of Europe at least, many Australian imaging practices are relatively new to the task of diagnostic imaging dose optimisation. In 2008 the Australian Government prescribed a requirement to periodically compare patient radiation doses with diagnostic reference levels (DRLs), where DRLs have been established. Until recently, Australia had only established DRLs for computed tomography (CT). Regardless, both professional society and individual efforts to improved data collection and develop optimisation strategies across a range of modalities continues. Progress in this field, principally with respect to CT and interventional fluoroscopy will be presented. In the US, dose reduction and optimization efforts for computed tomography have been promoted and mandated by several organizations and accrediting entities. This presentation will cover the general motivation, implementation, and implications of such efforts.

  16. In vivo isocenter dose in two hip prosthesis patients

    SciTech Connect

    Burleson, W.D.; Stutzman, C.D.; Stitt, J.A.; Karlsson, U.L.; Mian, T.A. )

    1991-06-01

    Hip prostheses may cause irradiation dose inhomogeneities in conventional four-field target volumes to the pelvis. Two patients, with bilateral and unilateral prostheses, were subjected to thermoluminescent dosimetry measurements in the prostatic urethra during 24 MV photon portal exposures. The results suggested a 13% decrease in absorbed dose only for conventional four-field beam geometry with bilateral prostheses, as compared to oblique four-field beam geometry or unilateral prosthesis. This supports the suggestion that beam technique modifications may be warranted for patients with hip prostheses.

  17. Radiation therapy for early stage unfavorable Hodgkin lymphoma: is dose reduction feasible?

    PubMed

    Laskar, Siddhartha; Kumar, Deepak P; Khanna, Nehal; Menon, Hari; Sengar, Manju; Arora, Brijesh; Gujral, Sumeet; Shet, Tanuja; Sridhar, Epari; Rangarajan, Venkatesh; Muckaden, Mary Ann; Nair, Reena; Banavali, Shripad

    2014-10-01

    One hundred and fifty-one patients aged between 3 and 70 years with early stage unfavorable Hodgkin lymphoma were included. Patients received 4-6 cycles of ABVD (doxorubicin, bleomycin, vinblastine and dacarbazine) chemotherapy and involved field radiation therapy (IFRT). The most common histology was mixed cellularity (43%). The majority had stage IIAX disease. IFRT doses were 25.2 Gy/14 fractions and 34.2 Gy/19 fractions for adults with a complete response (CR) and partial response (PR), respectively, while the doses were 19.8 Gy/11 fractions and 30.6 Gy/17 fractions, respectively, for children. After 60 months (median), the 10-year progression-free survival (PFS) and overall survival (OS) were 88.4% and 93.2%, respectively. On univariate analysis, prognostic factors with significant impact on PFS were age ≥ 18 years, nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) histology, extranodal disease and response to treatment. Extranodal disease had a significant impact on OS. On multivariate analysis, NLPHL histology (p = 0.001) and response at 3 months (p = 0.000) had a significant impact on PFS. There were no in-field relapses in patients with bulky disease receiving RT doses > 25.2 Gy. Chemotherapy related acute pulmonary toxicity was documented in 21.4% and 4.8% of patients after six and four cycles of ABVD chemotherapy (p = 0.041). Four cycles of ABVD and reduced dose IFRT resulted in optimal outcomes.

  18. Dosimetric impact of orthopedic metal artifact reduction (O-MAR) on spine SBRT patients.

    PubMed

    Shen, Zhilei Liu; Xia, Ping; Klahr, Paul; Djemil, Toufik

    2015-09-01

    The dosimetric impact of orthopedic metal artifact reduction (O-MAR) on spine SBRT patients has not been comprehensively studied, particularly with spinal prostheses in high-dose gradient regions. Using both phantom and patient datasets, we investigated dosimetric effects of O-MAR in combination of various metal locations and dose calculation algorithms. A physical phantom, with and without a titanium insert, was scanned. A clinical patient plan was applied to the artifact-free reference, non-O-MAR, and O-MAR phantom images with the titanium located either inside or outside of the tumor. Subsequently, five clinical patient plans were calculated with pencil beam and Monte Carlo (iPlan) on non-O-MAR and O-MAR patient images using an extended CT-density table. The dose differences for phantom plans and patient plans were analyzed using dose distributions, dose-volume histograms (DVHs), gamma index, and selected dosimetric endpoints. From both phantom plans and patient plans, O-MAR did not affect dose distributions and DVHs while minimizing metal artifacts. Among patient plans, we found that, when the same dose calculation method was used, the difference in the dosimetric endpoints between non-O-MAR and O-MAR datasets were small. In conclusion, for spine SBRT patients with spinal prostheses, O-MAR image reconstruction does not affect dose calculation accuracy while minimizing metal artifacts. Therefore, O-MAR images can be safely used for clinical spine SBRT treatment planning. PACS numbers: 87.53.Bn, 87.55.K-, 87.57.Q-, 87.57.cp.

  19. Comparison of Patient Dose in Two-Dimensional Carotid Arteriography and Three-Dimensional Rotational Angiography

    SciTech Connect

    Tsapaki, Virginia Vano, Eliseo; Mavrikou, Irini; Neofotistou, Vassiliki; Gallego, Juan Jose; Fernandez, Jose Miguel; Santos, Ernesto; Mendez, Jose

    2008-05-15

    Background and Purpose. It is known that interventional neuroradiology (IN) involves high radiation dose to both patients and staff even if performed by trained operators using modern fluoroscopic X-ray equipment and dose-reducing technology. Therefore, every new technology or imaging tool introduced, such as three-dimensional rotational angiography (3D RA), should be evaluated in terms of radiation dose. 3D RA requires a series with a large number of images in comparison with 2D angiography and it is sometimes considered a high-dose IN procedure. The literature is scarce on the 3D RA radiation dose and in particular there are no data on carotid arteriography (CA). The aim of this study was to investigate patient dose differences between 2D and 3D CA. Methods. The study included 35 patients undergoing 2D CA in hospital 1 and 25 patients undergoing 3D CA in hospital 2. Patient technical data collection included information on the kerma area product (KAP), fluoroscopy time (T), total number of series (S), and total number of acquired images (F). Results. Median KAP was 112 Gy cm{sup 2} and 41 Gy cm{sup 2} for hospitals 1 and 2, respectively, median T was 8.2 min and 5.1 min, median S was 13 and 4, and median F was 247 and 242. Entrance surface air-kerma rate, as measured in 'medium' fluoroscopy mode measured in 2D acquisition using a 20 cm phantom of polymethylmethacrylate, was 17.3 mGy/min for hospital 1 and 9.2 mGy/min for hospital 2. Conclusion. 3D CA allows a substantial reduction in patient radiation dose compared with 2D CA, while providing the necessary diagnostic information.

  20. Doses to patients from dental radiology in France

    SciTech Connect

    Benedittini, M.; Maccia, C.; Lefaure, C.; Fagnani, F. )

    1989-06-01

    In France, a national study was undertaken to estimate both dental radiology practices (equipment and activity) and the associated population collective dose. This study was done in two steps: A nationwide survey was conducted on the practitioner categories involved in dental radiology, and dosimetric measurements were performed on patients and on an anthropomorphic phantom by using conventional dental x-ray machines and pantomographic units. A total of 27.5 x 10(6) films were estimated to have been performed in 1984; 6% of them were pantomographic and 94% were conventional. Most of the organ doses measured for one intra-oral film were lower than 1 mGy (100 mrad); pantomogram dose values were generally higher than intra-oral ones. The collective effective dose equivalent figure was 2,000 person-Sv (2 x 10(5) person rem) leading to a per head dose equivalent of 0.037 mSv (3.7 mrem). The study allowed authors to identify ways to reduce the patient dose in France (e.g., implementing the use of long cone devices and controlling darkroom practices).

  1. Influence of dose reduction and iterative reconstruction on CT calcium scores: a multi-manufacturer dynamic phantom study.

    PubMed

    van der Werf, N R; Willemink, M J; Willems, T P; Greuter, M J W; Leiner, T

    2017-01-19

    To evaluate the influence of dose reduction in combination with iterative reconstruction (IR) on coronary calcium scores (CCS) in a dynamic phantom on state-of-the-art CT systems from different manufacturers. Calcified inserts in an anthropomorphic chest phantom were translated at 20 mm/s corresponding to heart rates between 60 and 75 bpm. The inserts were scanned five times with routinely used CCS protocols at reference dose and 40 and 80% dose reduction on four high-end CT systems. Filtered back projection (FBP) and increasing levels of IR were applied. Noise levels were determined. CCS, quantified as Agatston and mass scores, were compared to physical mass and scores at FBP reference dose. For the reference dose in combination with FBP, noise level variation between CT systems was less than 18%. Decreasing dose almost always resulted in increased CCS, while at increased levels of IR, CCS decreased again. The influence of IR on CCS was smaller than the influence of dose reduction. At reference dose, physical mass was underestimated 3-30%. All CT systems showed similar CCS at 40% dose reduction in combinations with specific reconstructions. For some CT systems CCS was not affected at 80% dose reduction, in combination with IR. This multivendor study showed that radiation dose reductions of 40% did not influence CCS in a dynamic phantom using state-of-the-art CT systems in combination with specific reconstruction settings. Dose reduction resulted in increased noise and consequently increased CCS, whereas increased IR resulted in decreased CCS.

  2. Dose-escalation study of octanoic acid in patients with essential tremor

    PubMed Central

    Voller, Bernhard; Lines, Emily; McCrossin, Gayle; Tinaz, Sule; Lungu, Codrin; Grimes, George; Starling, Judith; Potti, Gopal; Haubenberger, Dietrich

    2016-01-01

    BACKGROUND. Recently, 1-octanol has been shown to have efficacy in treating patients with essential tremor (ET). The primary metabolite of 1-octanol is octanoic acid (OA), which is now thought to be the active substance that mediates tremor suppression. Our aim was to describe the maximum tolerated dose (MTD) of oral OA in patients with ET and assess the pharmacokinetics (PK) and pharmacodynamics (PD) profile of OA. METHODS. The MTD was studied using an open-label, single-ascending 3 + 3 dose–escalation design. Predefined single doses ranged from 8 to 128 mg/kg, with grade 2 adverse events (AEs) defined as dose-limiting toxicity. Tremor was assessed using accelerometry, digital spiral analysis, and a standard clinical rating scale at baseline and up to 600 minutes after intake. Safety assessments and PK sampling were also performed. RESULTS. Dose-limiting toxicity was not reached. The most frequent AE was mild abdominal discomfort. Exposure (AUC) increased linearly with the dose. Secondary efficacy measures suggested a dose-dependent reduction of tremor. Accordingly, a single unified PK/PD model with an effect compartment and sigmoid maximum effect (Emax) response could be built that accounted well for the time profiles of plasma concentrations as well as effects on tremor severity across the 5 dose levels. CONCLUSION. Although our trial did not reach an MTD, a dose-dependent effect was demonstrated in the PK/PD model as well as in secondary efficacy outcomes. Future studies are needed to explore the safety in higher dose ranges and to confirm dose-dependent efficacy in a placebo-controlled design. TRIAL REGISTRATION. Clinicaltrials.gov NCT01468948 FUNDING. NINDS Intramural Research Program; TG Therapeutics Inc. PMID:26927672

  3. Effect of dialysis dose and membrane flux on hemoglobin cycling in hemodialysis patients.

    PubMed

    He, Liyu; Fu, Min; Chen, Xian; Liu, Hong; Chen, Xing; Peng, Xiaofei; Liu, Fuyou; Peng, Youming

    2015-04-01

    Many studies found that hemoglobin (Hb) fluctuation was closely related to the prognosis of the maintenance hemodialysis patients. We investigated the association of factors relating dialysis dose and dialyzer membrane with Hb levels. We undertook a randomized clinical trial in 140 patients undergoing thrice-weekly dialysis and assigned patients randomly to a standard or high dose of dialysis; Hb level was measured every month for 12 months. In the standard-dose group, the mean (±SD) urea reduction ratio was 65.1% ± 7.3%, the single-pool Kt/V was 1.26 ± 0.11, and the equilibrated Kt/V was 1.05 ± 0.09; in the high-dose group, the values were 73.5% ± 8.7%, 1.68 ± 0.15, and 1.47 ± 0.11, respectively. The standard deviation (SD) and residual SD (liner regression of Hb) values of Hb were significantly higher in the standard-dose group and low-flux group. The percentage achievement of target Hb in the high-dose dialysis group and high-flux dialyzer group was significantly higher than the standard-dose group and low-flux group, respectively. Patients undergoing hemodialysis thrice weekly appear to have benefit from a higher dialysis dose than that recommended by current KDQQI (Kidney Disease Qutcome Quality Initiative) guidelines or from the use of a high-flux membrane, which is in favor of maintaining stable Hb levels.

  4. A study evaluating the dependence of the patient dose on the CT dose change in a SPECT/CT scan

    NASA Astrophysics Data System (ADS)

    Kim, Woo-Hyun; Kim, Ho-Sung; Dong, Kyung-Rae; Chung, Woon-Kwan; Cho, Jae-Hwan; Shin, Jae-Woo

    2012-07-01

    This study assessed ways of reducing the patient dose by examining the dependence of the patient dose on the CT (computed tomography) dose in a SPECT (single-photon emission computed tomography)/CT scan. To measure the patient dose, we used Precedence 16 SPECT/CT along with a phantom for the CT dose measurement (CT dose phantom kit for adult's head and body, Model 76-414-4150), a 100-mm ionization chamber (CT Ion Chamber) and an X-ray detector (Victoreen Model 4000M+). In addition, the patient dose was evaluated under conditions similar to those for an actual examination using an ImPACT (imaging performance assessment of CT scanners) dosimetry calculator in the Monte Carlo simulation method. The experimental method involved the use of a CT dose phantom to measure the patient dose under different CT conditions (kVp and mAs) to determine the CTDI (CT dose index) under each condition. An ImPACT dosimetry calculator was also used to measure CTDIw (CT dose index water ), CTDIv (CT dose index volume ), DLP (dose-length product), and effective dose. According to the patient dose measurements using the CT dose phantom, the CTDI showed an approximately 54 fold difference between when the maximum (140 kVp and 250 mAs) and the minimum dose (90 kVp and 25 mAs) was used. The CTDI showed a 4.2 fold difference between the conditions (120 kVp and 200 mAs) used mainly in a common CT scan and the conditions (120 kVp and 50 mAs) used mainly in a SPECT/CT scan. According to the measurement results using the dosimetry calculator, the effective dose showed an approximately 35 fold difference between the conditions for the maximum and the minimum doses, as in the case with the CT dose phantom. The effective dose showed a 4.1 fold difference between the conditions used mainly in a common CT scan and those used mainly in a SPECT/CT scan. This study examined the patient dose by reducing the CT dose in a SPECT/CT scan. As various examinations can be conducted due to the development of

  5. Patient dose monitoring in Dubai in radiography and interventional procedures.

    PubMed

    AlSuwaidi, J S; AlMazrouei, N K; Pottybindu, S; Siraj, M; Mathew, D; Al Blooshi, A A; Kuriakose, V P

    2015-06-01

    This paper presents ongoing actions in Dubai on patient dose monitoring in digital radiographic examinations, mammography, interventional procedures, and dental radiological procedures. The aim of Dubai Health Authority (DHA) is to move towards the establishment of local diagnostic reference levels. DHA has participated in national and regional projects under the umbrella of the International Atomic Energy Agency. The need for local radiation protection educational programmes and wider patient dosimetry monitoring and recording emerged from this work.

  6. A real time dose monitoring and dose reconstruction tool for patient specific VMAT QA and delivery

    SciTech Connect

    Tyagi, Neelam; Yang Kai; Gersten, David; Yan Di

    2012-12-15

    Purpose: To develop a real time dose monitoring and dose reconstruction tool to identify and quantify sources of errors during patient specific volumetric modulated arc therapy (VMAT) delivery and quality assurance. Methods: The authors develop a VMAT delivery monitor tool called linac data monitor that connects to the linac in clinical mode and records, displays, and compares real time machine parameters with the planned parameters. A new measure, called integral error, keeps a running total of leaf overshoot and undershoot errors in each leaf pair, multiplied by leaf width, and the amount of time during which the error exists in monitor unit delivery. Another tool reconstructs Pinnacle{sup 3} Trade-Mark-Sign format delivered plan based on the saved machine logfile and recalculates actual delivered dose in patient anatomy. Delivery characteristics of various standard fractionation and stereotactic body radiation therapy (SBRT) VMAT plans delivered on Elekta Axesse and Synergy linacs were quantified. Results: The MLC and gantry errors for all the treatment sites were 0.00 {+-} 0.59 mm and 0.05 {+-} 0.31 Degree-Sign , indicating a good MLC gain calibration. Standard fractionation plans had a larger gantry error than SBRT plans due to frequent dose rate changes. On average, the MLC errors were negligible but larger errors of up to 6 mm and 2.5 Degree-Sign were seen when dose rate varied frequently. Large gantry errors occurred during the acceleration and deceleration process, and correlated well with MLC errors (r= 0.858, p= 0.0004). PTV mean, minimum, and maximum dose discrepancies were 0.87 {+-} 0.21%, 0.99 {+-} 0.59%, and 1.18 {+-} 0.52%, respectively. The organs at risk (OAR) doses were within 2.5%, except some OARs that showed up to 5.6% discrepancy in maximum dose. Real time displayed normalized total positive integral error (normalized to the total monitor units) correlated linearly with MLC (r= 0.9279, p < 0.001) and gantry errors (r= 0.742, p= 0.005). There

  7. Effects of dose reduction on the detectability of standardized radiolucent lesions in digital panoramic radiography.

    PubMed

    Dula, K; Sanderink, G; van der Stelt, P F; Mini, R; Buser, D

    1998-08-01

    Dose reduction in digital panoramic radiography was studied. Intentional underexposure was performed with the Orthophos DS while six different human mandibles were radiographed. Exposure settings were 69 kV/15 mA (standard), 64 kV/16 mA, and 60 kV/16 mA. Standardized spherical defects, each either 1 or 1.25 mm in diameter, were simulated in 288 of 432 images, and seven observers decided whether defects were present or not. Areas under the receiver operating characteristics curves were calculated. They showed no significant differences in the detectability of the 1-mm defect at 69, 64, or 60 kV. For the 1.25-mm defect, no difference was found between the 69 and 60 kV images, but a statistically significant different detectability was found for 64 kV images in comparison with both 69 and 60 kV images. A dose reduction of up to 43% was ascertained with a Pedo-RT-Humanoid phantom when panoramic radiography was performed at 60 kV/16 mA. The conclusion is that with the Orthophos DS, it seems possible to reduce the dose rate of x-rays without loss of diagnostic quality in the case of radiolucent changes.

  8. Radiation dose reduction in digital radiography using wavelet-based image processing methods

    NASA Astrophysics Data System (ADS)

    Watanabe, Haruyuki; Tsai, Du-Yih; Lee, Yongbum; Matsuyama, Eri; Kojima, Katsuyuki

    2011-03-01

    In this paper, we investigate the effect of the use of wavelet transform for image processing on radiation dose reduction in computed radiography (CR), by measuring various physical characteristics of the wavelet-transformed images. Moreover, we propose a wavelet-based method for offering a possibility to reduce radiation dose while maintaining a clinically acceptable image quality. The proposed method integrates the advantages of a previously proposed technique, i.e., sigmoid-type transfer curve for wavelet coefficient weighting adjustment technique, as well as a wavelet soft-thresholding technique. The former can improve contrast and spatial resolution of CR images, the latter is able to improve the performance of image noise. In the investigation of physical characteristics, modulation transfer function, noise power spectrum, and contrast-to-noise ratio of CR images processed by the proposed method and other different methods were measured and compared. Furthermore, visual evaluation was performed using Scheffe's pair comparison method. Experimental results showed that the proposed method could improve overall image quality as compared to other methods. Our visual evaluation showed that an approximately 40% reduction in exposure dose might be achieved in hip joint radiography by using the proposed method.

  9. Assessment of patient dose in medical processes by in-vivo dose measuring devices: A review

    NASA Astrophysics Data System (ADS)

    Tuncel, Nina

    2016-11-01

    In-vivo dosimetry (IVD) in medicine especially in radiation therapy is a well-established and recommended procedure for the estimation of the dose delivered to a patient during the radiation treatment. It became even more important with the emerging use of new and more complex radiotherapy techniques such as intensity-modulated or image-guided radiation therapy. While IVD has been used in brachytherapy for decades and the initial motivation for performing was mainly to assess doses to organs at risk by direct measurements, it is now possible to calculate 3D for detection of deviations or errors. In-vivo dosimeters can be divided into real-time and passive detectors that need some finite time following irradiation for their analysis. They require a calibration against a calibrated ionization chamber in a known radiation field. Most of these detectors have a response that is energy and/or dose rate dependent and consequently require adjustments of the response to account for changes in the actual radiation conditions compared to the calibration situation. Correction factors are therefore necessary to take. Today, the most common dosimeters for patients' dose verification through in-vivo measurements are semiconductor diodes, thermo-luminescent dosimeters, optically stimulated luminescence dosimeters, metal-oxide-semiconductor field-effect transistors and plastic scintillator detectors with small outer diameters.

  10. Patient-specific radiation dose and cancer risk estimation in CT: Part II. Application to patients

    SciTech Connect

    Li Xiang; Samei, Ehsan; Segars, W. Paul; Sturgeon, Gregory M.; Colsher, James G.; Toncheva, Greta; Yoshizumi, Terry T.; Frush, Donald P.

    2011-01-15

    Purpose: Current methods for estimating and reporting radiation dose from CT examinations are largely patient-generic; the body size and hence dose variation from patient to patient is not reflected. Furthermore, the current protocol designs rely on dose as a surrogate for the risk of cancer incidence, neglecting the strong dependence of risk on age and gender. The purpose of this study was to develop a method for estimating patient-specific radiation dose and cancer risk from CT examinations. Methods: The study included two patients (a 5-week-old female patient and a 12-year-old male patient), who underwent 64-slice CT examinations (LightSpeed VCT, GE Healthcare) of the chest, abdomen, and pelvis at our institution in 2006. For each patient, a nonuniform rational B-spine (NURBS) based full-body computer model was created based on the patient's clinical CT data. Large organs and structures inside the image volume were individually segmented and modeled. Other organs were created by transforming an existing adult male or female full-body computer model (developed from visible human data) to match the framework defined by the segmented organs, referencing the organ volume and anthropometry data in ICRP Publication 89. A Monte Carlo program previously developed and validated for dose simulation on the LightSpeed VCT scanner was used to estimate patient-specific organ dose, from which effective dose and risks of cancer incidence were derived. Patient-specific organ dose and effective dose were compared with patient-generic CT dose quantities in current clinical use: the volume-weighted CT dose index (CTDI{sub vol}) and the effective dose derived from the dose-length product (DLP). Results: The effective dose for the CT examination of the newborn patient (5.7 mSv) was higher but comparable to that for the CT examination of the teenager patient (4.9 mSv) due to the size-based clinical CT protocols at our institution, which employ lower scan techniques for smaller

  11. Angular on-line tube current modulation in multidetector CT examinations of children and adults: The influence of different scanning parameters on dose reduction

    SciTech Connect

    Papadakis, Antonios E.; Perisinakis, Kostas; Damilakis, John

    2007-07-15

    The purpose of this study was to assess the potential of angular on-line tube current modulation on dose reduction in pediatric and adult patients undergoing multidetector computed tomography (MDCT) examinations. Five physical anthropomorphic phantoms that simulate the average individual as neonate, 1-year-old, 5-year-old, 10-year-old, and adult were employed in the current study. Phantoms were scanned with the use of on-line tube current modulation (TCM). Percent dose reduction (%DR) factors achieved by applying TCM, were determined for standard protocols used for head and neck, shoulder, thorax, thorax and abdomen, abdomen, abdomen and pelvis, pelvis, and whole body examinations. A preliminary study on the application of TCM in MDCT examinations of adult patients was performed to validate the results obtained in anthropomorphic phantoms. Dose reduction was estimated as the percentage difference of the modulated milliamperes for each scan and the preset milliamperes prescribed by the scan protocol. The dose reduction in children was found to be much lower than the corresponding reduction achieved for adults. For helical scans the %DR factors, ranged between 1.6% and 7.4% for the neonate, 2.9% and 8.7% for the 1-year old, 2% and 6% for the 5-year-old, 5% and 10.9% for the 10-year-old, and 10.4% and 20.7% for the adult individual. For sequential scans the corresponding %DR factors ranged between 1.3% and 6.7%, 4.5% and 11%, 4.2% and 6.6%, 6.4% and 12.3%, and 8.9% and 23.3%, respectively. Broader beam collimations are associated with decreased %DR factors, when other scanning parameters are held constant. TCM did not impair image noise. In adult patients, the %DR values were found to be in good agreement with the corresponding results obtained in the anthropomorphic adult phantom. In conclusion, on-line TCM may be considered as a valuable tool for reducing dose in routine CT examinations of pediatric and adult patients. However, the dose reduction achieved with TCM

  12. Warfarin Dose Model for the Prediction of Stable Maintenance Dose in Indian Patients.

    PubMed

    Gaikwad, Tejasvita; Ghosh, Kanjaksha; Avery, Peter; Kamali, Farhad; Shetty, Shrimati

    2017-01-01

    The main aim of this study was to screen various genetic and nongenetic factors that are known to alter warfarin response and to generate a model to predict stable warfarin maintenance dose for Indian patients. The study comprised of 300 warfarin-treated patients. Followed by extensive literature review, 10 single-nucleotide polymorphisms, that is, VKORC1-1639 G>A (rs9923231), CYP2C9*2 (rs1799853), CYP2C9*3 (rs1057910), FVII R353Q (rs6046), GGCX 12970 C>G (rs11676382), CALU c.*4A>G (rs1043550), EPHX1 c.337T>C (rs1051740), GGCX: c.214+597G>A (rs12714145), GGCX: 8016G>A (rs699664), and CYP4F2 V433M (rs2108622), and 5 nongenetic factors, that is, age, gender, smoking, alcoholism, and diet, were selected to find their association with warfarin response. The univariate analysis was carried out for 15 variables (10 genetic and 5 nongenetic). Five variables, that is, VKORC1-1639 G>A, CYP2C9*2, CYP2C9*3, age, and diet, were found to be significantly associated with warfarin response in univariate analysis. These 5 variables were entered in stepwise and multiple regression analysis to generate a prediction model for stable warfarin maintenance dose. The generated model scored R(2) of .67, which indicates that this model can explain 67% of warfarin dose variability. The generated model will help in prescribing more accurate warfarin maintenance dosing in Indian patients and will also help in minimizing warfarin-induced adverse drug reactions and a better quality of life in these patients.

  13. Radiation dose reduction using a neck detection algorithm for single spiral brain and cervical spine CT acquisition in the trauma setting.

    PubMed

    Ardley, Nicholas D; Lau, Ken K; Buchan, Kevin

    2013-12-01

    Cervical spine injuries occur in 4-8 % of adults with head trauma. Dual acquisition technique has been traditionally used for the CT scanning of brain and cervical spine. The purpose of this study was to determine the efficacy of radiation dose reduction by using a single acquisition technique that incorporated both anatomical regions with a dedicated neck detection algorithm. Thirty trauma patients for brain and cervical spine CT were included and were scanned with the single acquisition technique. The radiation doses from the single CT acquisition technique with the neck detection algorithm, which allowed appropriate independent dose administration relevant to brain and cervical spine regions, were recorded. Comparison was made both to the doses calculated from the simulation of the traditional dual acquisitions with matching parameters, and to the doses of retrospective dual acquisition legacy technique with the same sample size. The mean simulated dose for the traditional dual acquisition technique was 3.99 mSv, comparable to the average dose of 4.2 mSv from 30 previous patients who had CT of brain and cervical spine as dual acquisitions. The mean dose from the single acquisition technique was 3.35 mSv, resulting in a 16 % overall dose reduction. The images from the single acquisition technique were of excellent diagnostic quality. The new single acquisition CT technique incorporating the neck detection algorithm for brain and cervical spine significantly reduces the overall radiation dose by eliminating the unavoidable overlapping range between 2 anatomical regions which occurs with the traditional dual acquisition technique.

  14. Estimating radiation dose to organs of patients undergoing conventional and novel multidetector CT exams using Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Angel, Erin

    Advances in Computed Tomography (CT) technology have led to an increase in the modality's diagnostic capabilities and therefore its utilization, which has in turn led to an increase in radiation exposure to the patient population. As a result, CT imaging currently constitutes approximately half of the collective exposure to ionizing radiation from medical procedures. In order to understand the radiation risk, it is necessary to estimate the radiation doses absorbed by patients undergoing CT imaging. The most widely accepted risk models are based on radiosensitive organ dose as opposed to whole body dose. In this research, radiosensitive organ dose was estimated using Monte Carlo based simulations incorporating detailed multidetector CT (MDCT) scanner models, specific scan protocols, and using patient models based on accurate patient anatomy and representing a range of patient sizes. Organ dose estimates were estimated for clinical MDCT exam protocols which pose a specific concern for radiosensitive organs or regions. These dose estimates include estimation of fetal dose for pregnant patients undergoing abdomen pelvis CT exams or undergoing exams to diagnose pulmonary embolism and venous thromboembolism. Breast and lung dose were estimated for patients undergoing coronary CTA imaging, conventional fixed tube current chest CT, and conventional tube current modulated (TCM) chest CT exams. The correlation of organ dose with patient size was quantified for pregnant patients undergoing abdomen/pelvis exams and for all breast and lung dose estimates presented. Novel dose reduction techniques were developed that incorporate organ location and are specifically designed to reduce close to radiosensitive organs during CT acquisition. A generalizable model was created for simulating conventional and novel attenuation-based TCM algorithms which can be used in simulations estimating organ dose for any patient model. The generalizable model is a significant contribution of this

  15. Radiation dose reduction in computed tomography perfusion using spatial-temporal Bayesian methods

    NASA Astrophysics Data System (ADS)

    Fang, Ruogu; Raj, Ashish; Chen, Tsuhan; Sanelli, Pina C.

    2012-03-01

    In current computed tomography (CT) examinations, the associated X-ray radiation dose is of significant concern to patients and operators, especially CT perfusion (CTP) imaging that has higher radiation dose due to its cine scanning technique. A simple and cost-effective means to perform the examinations is to lower the milliampere-seconds (mAs) parameter as low as reasonably achievable in data acquisition. However, lowering the mAs parameter will unavoidably increase data noise and degrade CT perfusion maps greatly if no adequate noise control is applied during image reconstruction. To capture the essential dynamics of CT perfusion, a simple spatial-temporal Bayesian method that uses a piecewise parametric model of the residual function is used, and then the model parameters are estimated from a Bayesian formulation of prior smoothness constraints on perfusion parameters. From the fitted residual function, reliable CTP parameter maps are obtained from low dose CT data. The merit of this scheme exists in the combination of analytical piecewise residual function with Bayesian framework using a simpler prior spatial constrain for CT perfusion application. On a dataset of 22 patients, this dynamic spatial-temporal Bayesian model yielded an increase in signal-tonoise-ratio (SNR) of 78% and a decrease in mean-square-error (MSE) of 40% at low dose radiation of 43mA.

  16. Moxifloxacin dosing in post-bariatric surgery patients

    PubMed Central

    Colin, Pieter; Eleveld, Douglas J; Struys, Michel M R F; T'Jollyn, Huybrecht; Bortel, Luc M Van; Ruige, Johannes; De Waele, Jan; Van Bocxlaer, Jan; Boussery, Koen

    2014-01-01

    Introduction Given the ever increasing number of obese patients and obesity related bypass surgery, dosing recommendations in the post-bypass population are needed. Using a population pharmacokinetic (PK) analysis and PK–pharmacodynamic (PD) simulations, we investigated whether adequate moxifloxacin concentrations are achieved in this population. Methods In this modelling and simulation study we used data from a trial on moxifloxacin PK. In this trial, volunteers who had previously undergone bariatric surgery (at least 6 months prior to inclusion), received two doses (intravenous and oral) of 400 mg moxifloxacin administered on two occasions. Results In contrast to other papers, we found that moxifloxacin PK were best described by a three compartmental model using lean body mass (LBM) as a predictor for moxifloxacin clearance. Furthermore, we showed that the probability of target attainment for bacterial eradication against a hypothetical Streptococcus pneumoniae infection is compromised in patients with higher LBM, especially when targeting microorganisms with minimum inhibitory concentrations (MICs) of 0.5 mg l−1 or higher (probability of target attainment (PTA) approaching zero). When considering the targets for suppression of bacterial resistance formation, even at MIC values as low as 0.25 mg l−1, standard moxifloxacin dosing does not attain adequate levels in this population. Furthermore, for patients with a LBM of 78 kg or higher, the probability of hitting this target approaches zero. Conclusions Throughout our PK–PD simulation study, it became apparent that, whenever optimal bacterial resistance suppression is deemed necessary, the standard moxifloxacin dosing will not be sufficient. Furthermore, our study emphasizes the need for a LBM based individualized dosing of moxifloxacin in this patient population. PMID:24313873

  17. Dose reduction in CT urography and vasculature phantom studies using model-based iterative reconstruction.

    PubMed

    Page, Leland; Wei, Wei; Kundra, Vikas; Rong, John

    2016-11-08

    To evaluate the feasibility of radiation dose reduction using model-based iterative reconstruction (MBIR) for evaluating the ureters and vasculature in a phantom, a tissue-equivalent CT dose phantom was scanned using a 64-channel CT scan-ner. Tubes of varying diameters filled with different dilutions of a contrast agent, simulating ureters or vessels, were inserted into the center of the phantom. Each combination was scanned using an existing renal protocol at 140 kVp or 120 kVp, yielding a display volumetric CT dose index (CTDIvol) of 24 mGy. The scans were repeated using reduced scan techniques to achieve lower radiation doses down to 0.8 mGy. The images were reconstructed using filtered back-projection (FBP) and model-based iterative reconstruction (MBIR). The noise and contrast-to-noise ratio (CNR) was measured for each contrast object. Comparisons between the two reconstruction methods at different dose levels were evaluated using a factorial design. At each CTDIvol the measured image noise was lower using MBIR compared to FBP (p < 0.0001). At low doses, the percent change in measured image noise between FBP and MBIR was larger. For the 12 mm object simulating a ureter or large vessel with an HU of 600, the measured CNR using MBIR at a CTDIvol of 1.7 mGy was greater than the CNR of FBP at a CTIDvol of 24 mGy (p < 0.0001). For the 5 mm object simulating a medium-sized vessel with a HU of 250, the mea-sured CNR using MBIR at a CTDIvol of 1.7 mGy was equivalent to that of FBP at a CTDIvol of 24 mGy. For the 2 mm, 100 HU object simulating a small vessel, the measured CNR using MBIR at a CTDIvol of 1.7 mGy was equivalent to that of FBP at a CTDIvol of 24 mGy. Low-dose (3.6 mGy) CT imaging of vasculature and ureter phantoms using MBIR results in similar noise and CNR compared to FBP at approximately one-sixth the dose. This suggests that, using MBIR, a one milliSievert exam of the ureters and vasculature may be clinically possible whilst still maintaining adequate

  18. Effects of low-dose mindfulness-based stress reduction (MBSR-ld) on working adults.

    PubMed

    Klatt, Maryanna D; Buckworth, Janet; Malarkey, William B

    2009-06-01

    Mindfulness-based stress reduction (MBSR) has produced behavioral, psychological, and physiological benefits, but these programs typically require a substantial time commitment from the participants. This study assessed the effects of a shortened (low-dose [ld]) work-site MBSR intervention (MBSR-ld) on indicators of stress in healthy working adults to determine if results similar to those obtained in traditional MBSR could be demonstrated. Participants were randomized into MBSR-ld and wait-list control groups. Self-reported perceived stress, sleep quality, and mindfulness were measured at the beginning and end of the 6-week intervention. Salivary cortisol was assessed weekly. Significant reductions in perceived stress (p = .0025) and increases in mindfulness (p = .0149) were obtained for only the MBSR-ld group (n = 22). Scores on the global measure of sleep improved for the MBSR-ld group (p = .0018) as well as for the control group (p = .0072; n = 20). Implications and future research are discussed.

  19. Characterization of statistical prior image constrained compressed sensing (PICCS): II. Application to dose reduction

    SciTech Connect

    Lauzier, Pascal Theriault; Chen Guanghong

    2013-02-15

    Purpose: The ionizing radiation imparted to patients during computed tomography exams is raising concerns. This paper studies the performance of a scheme called dose reduction using prior image constrained compressed sensing (DR-PICCS). The purpose of this study is to characterize the effects of a statistical model of x-ray detection in the DR-PICCS framework and its impact on spatial resolution. Methods: Both numerical simulations with known ground truth and in vivo animal dataset were used in this study. In numerical simulations, a phantom was simulated with Poisson noise and with varying levels of eccentricity. Both the conventional filtered backprojection (FBP) and the PICCS algorithms were used to reconstruct images. In PICCS reconstructions, the prior image was generated using two different denoising methods: a simple Gaussian blur and a more advanced diffusion filter. Due to the lack of shift-invariance in nonlinear image reconstruction such as the one studied in this paper, the concept of local spatial resolution was used to study the sharpness of a reconstructed image. Specifically, a directional metric of image sharpness, the so-called pseudopoint spread function (pseudo-PSF), was employed to investigate local spatial resolution. Results: In the numerical studies, the pseudo-PSF was reduced from twice the voxel width in the prior image down to less than 1.1 times the voxel width in DR-PICCS reconstructions when the statistical model was not included. At the same noise level, when statistical weighting was used, the pseudo-PSF width in DR-PICCS reconstructed images varied between 1.5 and 0.75 times the voxel width depending on the direction along which it was measured. However, this anisotropy was largely eliminated when the prior image was generated using diffusion filtering; the pseudo-PSF width was reduced to below one voxel width in that case. In the in vivo study, a fourfold improvement in CNR was achieved while qualitatively maintaining sharpness

  20. Patient doses and dosimetric evaluations in interventional cardiology.

    PubMed

    Bor, Dogan; Olğar, Turan; Toklu, Türkay; Cağlan, Ayça; Onal, Elif; Padovani, Renato

    2009-03-01

    Interventional cardiological examinations may be associated with excessive radiation exposures which may cause skin injuries and higher probabilities of stochastic effects. Dose-area product (DAP) and skin doses of 325 patients were measured using alternative dosimetric techniques for different cardiological examinations. Data were collected from five different systems with the involvement of 11 cardiologists. All these dosimetric information has been collected separately for each of 10 projections together with the exposure parameters of X-ray systems. Mean DAP values measured with a transparent ion chamber were 49.1 Gy cm(2), 66.8 Gy cm(2), 106.9 Gy cm(2) and 124.7 Gy cm(2), respectively, for coronary angiography (CA), percutaneous transluminal coronary angioplasty (PTCA) or stent (PT-SI), coronary angiography and/or PTCA and/or stent (CA-PT-SI), and ablation examinations. Radiochromic films, thermoluminescent dosimeters (TLD) and point measurement of air kerma (AK) were carried out for skin dose assessments. Skin doses of 23 patients measured with radiochromic films were found to be between 2 Gy and 6 Gy. Although the complexity of the procedures was the major reason for these excessive doses, considerable contributions of high X-ray output of some fluoroscopy units were also noticed. In addition to the direct measurement of DAP, alternative DAP values were also determined from the skin dose measurement techniques; exposed areas were summed on digitized radiochromic films in one technique, The product of AK reading with X-ray field size measured at the patient entrance using slow X-ray films was taken as another DAP. Good correlations were found among the DAP results and also between the entrance skin doses calculated from AK measurements and direct DAP readings (R(2)=0.91). A trigger DAP value of 130 Gy cm(2) for the 2 Gy of skin doses was derived from this relationship. Collection of dosimetric data for each projection was also investigated regarding a

  1. Predicting Maintenance Doses of Vancomycin for Hospitalized Patients Undergoing Hemodialysis

    PubMed Central

    El Nekidy, Wasim S; El-Masri, Maher M; Umstead, Greg S; Dehoorne-Smith, Michelle

    2016-01-01

    Background Methicillin-resistant Staphylococcus aureus is a leading cause of death in patients undergoing hemodialysis. However, controversy exists about the optimal dose of vancomycin that will yield the recommended pre-hemodialysis serum concentration of 15–20 mg/L. Objective To develop a data-driven model to optimize the accuracy of maintenance dosing of vancomycin for patients undergoing hemodialysis. Methods A prospective observational cohort study was performed with 164 observations obtained from a convenience sample of 63 patients undergoing hemodialysis. All vancomycin doses were given on the floor after completion of a hemodialysis session. Multivariate linear generalized estimating equation analysis was used to examine independent predictors of pre-hemodialysis serum vancomycin concentration. Results Pre-hemodialysis serum vancomycin concentration was independently associated with maintenance dose (B = 0.658, p < 0.001), baseline pre-hemodialysis serum concentration of the drug (B = 0.492, p < 0.001), and interdialytic interval (B = −2.133, p < 0.001). According to the best of 4 models that were developed, the maintenance dose of vancomycin required to achieve a pre-hemodialysis serum concentration of 15–20 mg/L, if the baseline serum concentration of the drug was also 15–20 mg/L, was 5.9 mg/kg with interdialytic interval of 48 h and 7.1 mg/kg with interdialytic interval of 72 h. However, if the baseline pre-hemodialysis serum concentration was 10–14.99 mg/L, the required dose increased to 9.2 mg/kg with an interdialytic interval of 48 h and 10.0 mg/kg with an interdialytic interval of 72 h. Conclusions The maintenance dose of vancomycin varied according to baseline pre-hemodialysis serum concentration of the drug and interdialytic interval. The current practice of targeting a pre-hemodialysis concentration of 15–20 mg/L may be difficult to achieve for the majority of patients undergoing hemodialysis. PMID:27826151

  2. Photon beam dose distributions for patients with implanted temporary tissue expanders

    NASA Astrophysics Data System (ADS)

    Asena, A.; Kairn, T.; Crowe, S. B.; Trapp, J. V.

    2015-01-01

    This study examines the effects of temporary tissue expanders (TTEs) on the dose distributions of photon beams in breast cancer radiotherapy treatments. EBT2 radiochromic film and ion chamber measurements were taken to quantify the attenuation and backscatter effects of the inhomogeneity. Results illustrate that the internal magnetic port present in a tissue expander causes a dose reduction of approximately 25% in photon tangent fields immediately downstream of the implant. It was also shown that the silicone elastomer shell of the tissue expander reduced the dose to the target volume by as much as 8%. This work demonstrates the importance for an accurately modelled high-density implant in the treatment planning system for post-mastectomy breast cancer patients.

  3. Radiation dose reduction and new image modalities development for interventional C-arm imaging system

    NASA Astrophysics Data System (ADS)

    Niu, Kai

    Cardiovascular disease and stroke are the leading health problems and causes of death in the US. Due to the minimally invasive nature of the evolution of image guided techniques, interventional radiological procedures are becoming more common and are preferred in treating many cardiovascular diseases and strokes. In addition, with the recent advances in hardware and device technology, the speed and efficacy of interventional treatment has significantly improved. This implies that more image modalities can be developed based on the current C-arm system and patients treated in interventional suites can potentially experience better health outcomes. However, during the treatment patients are irradiated with substantial amounts of ionizing radiation with a high dose rate (digital subtraction angiography (DSA) with 3muGy/frame and 3D cone beam CT image with 0.36muGy/frame for a Siemens Artis Zee biplane system) and/or a long irradiation time (a roadmapping image sequence can be as long as one hour during aneurysm embolization). As a result, the patient entrance dose is extremely high. Despite the fact that the radiation dose is already substantial, image quality is not always satisfactory. By default a temporal average is used in roadmapping images to overcome poor image quality, but this technique can result in motion blurred images. Therefore, reducing radiation dose while maintaining or even improving the image quality is an important area for continued research. This thesis is focused on improving the clinical applications of C-arm cone beam CT systems in two ways: (1) Improve the performance of current image modalities on the C-arm system. (2) Develop new image modalities based on the current system. To be more specific, the objectives are to reduce radiation dose for current modalities (e.g., DSA, fluoroscopy, roadmapping, and cone beam CT) and enable cone beam CT perfusion and time resolved cone beam CT angiography that can be used to diagnose and triage acute

  4. SU-E-T-329: Dosimetric Impact of Implementing Metal Artifact Reduction Methods and Metal Energy Deposition Kernels for Photon Dose Calculations

    SciTech Connect

    Huang, J; Followill, D; Howell, R; Liu, X; Mirkovic, D; Stingo, F; Kry, S

    2015-06-15

    Purpose: To investigate two strategies for reducing dose calculation errors near metal implants: use of CT metal artifact reduction methods and implementation of metal-based energy deposition kernels in the convolution/superposition (C/S) method. Methods: Radiochromic film was used to measure the dose upstream and downstream of titanium and Cerrobend implants. To assess the dosimetric impact of metal artifact reduction methods, dose calculations were performed using baseline, uncorrected images and metal artifact reduction Methods: Philips O-MAR, GE’s monochromatic gemstone spectral imaging (GSI) using dual-energy CT, and GSI imaging with metal artifact reduction software applied (MARs).To assess the impact of metal kernels, titanium and silver kernels were implemented into a commercial collapsed cone C/S algorithm. Results: The CT artifact reduction methods were more successful for titanium than Cerrobend. Interestingly, for beams traversing the metal implant, we found that errors in the dimensions of the metal in the CT images were more important for dose calculation accuracy than reduction of imaging artifacts. The MARs algorithm caused a distortion in the shape of the titanium implant that substantially worsened the calculation accuracy. In comparison to water kernel dose calculations, metal kernels resulted in better modeling of the increased backscatter dose at the upstream interface but decreased accuracy directly downstream of the metal. We also found that the success of metal kernels was dependent on dose grid size, with smaller calculation voxels giving better accuracy. Conclusion: Our study yielded mixed results, with neither the metal artifact reduction methods nor the metal kernels being globally effective at improving dose calculation accuracy. However, some successes were observed. The MARs algorithm decreased errors downstream of Cerrobend by a factor of two, and metal kernels resulted in more accurate backscatter dose upstream of metals. Thus

  5. Pharmacokinetic characterization of baclofen in patients with chronic kidney disease: dose adjustment recommendations.

    PubMed

    Vlavonou, Raphaël; Perreault, Marc M; Barrière, Olivier; Shink, Eric; Tremblay, Pierre-Olivier; Larouche, Richard; Pichette, Vincent; Tanguay, Mario

    2014-05-01

    The pharmacokinetics of baclofen is well delineated in subjects with normal kidney function (KF); however, pharmacokinetics data in patients with chronic kidney disease (CKD) are not and dosage recommendations remain empirical. The effects of CKD on baclofen pharmacokinetics were assessed through a multi-center, open-label, single 5-mg dose, pharmacokinetics study. The KF was measured as the creatinine clearance (CrCL) calculated with the Cockroft-Gault (C-G) equation or as the estimated glomerular filtration rate (eGFR) using subjects' CKD-EPI equation. Subjects were assigned to 1 of 4 groups based on their CrCL (>80 mL/min, 50-80 mL/min; 30-50 mL/min and <30 mL/min). Cmax was not statistically different between the groups, while AUC and T1/2el increased, and CL/F decreased, with increasing severity of CKD. Baclofen's oral clearance and CrCL were statistically significantly correlated, and the trend was the same when classifying subjects either with the CKD-EPI or C-G equations. Linear equations using KF as variable were set to recommend individual dose reduction in CKD patients. Results suggest a mean dose reduction of 1/3, 1/2, and 2/3 in patients with mild, moderate, and severe CKD respectively, in order to achieve baclofen exposure comparable to that observed in healthy subjects.

  6. Patient doses from fluoroscopically guided cardiac procedures in pediatrics

    NASA Astrophysics Data System (ADS)

    Martinez, L. C.; Vano, E.; Gutierrez, F.; Rodriguez, C.; Gilarranz, R.; Manzanas, M. J.

    2007-08-01

    Infants and children are a higher risk population for radiation cancer induction compared to adults. Although some values on pediatric patient doses for cardiac procedures have been reported, data to determine reference levels are scarce, especially when compared to those available for adults in diagnostic and therapeutic procedures. The aim of this study is to make a new contribution to the scarce published data in pediatric cardiac procedures and help in the determination of future dose reference levels. This paper presents a set of patient dose values, in terms of air kerma area product (KAP) and entrance surface air kerma (ESAK), measured in a pediatric cardiac catheterization laboratory equipped with a biplane x-ray system with dynamic flat panel detectors. Cardiologists were properly trained in radiation protection. The study includes 137 patients aged between 10 days and 16 years who underwent diagnostic catheterizations or therapeutic procedures. Demographic data and technical details of the procedures were also gathered. The x-ray system was submitted to a quality control programme, including the calibration of the transmission ionization chamber. The age distribution of the patients was 47 for <1 year; 52 for 1-<5 years; 25 for 5-<10 years and 13 for 10-<16 years. Median values of KAP were 1.9, 2.9, 4.5 and 15.4 Gy cm2 respectively for the four age bands. These KAP values increase by a factor of 8 when moving through the four age bands. The probability of a fatal cancer per fluoroscopically guided cardiac procedure is about 0.07%. Median values of ESAK for the four age bands were 46, 50, 56 and 163 mGy, which lie far below the threshold for deterministic effects on the skin. These dose values are lower than those published in previous papers.

  7. Patient doses from fluoroscopically guided cardiac procedures in pediatrics.

    PubMed

    Martinez, L C; Vano, E; Gutierrez, F; Rodriguez, C; Gilarranz, R; Manzanas, M J

    2007-08-21

    Infants and children are a higher risk population for radiation cancer induction compared to adults. Although some values on pediatric patient doses for cardiac procedures have been reported, data to determine reference levels are scarce, especially when compared to those available for adults in diagnostic and therapeutic procedures. The aim of this study is to make a new contribution to the scarce published data in pediatric cardiac procedures and help in the determination of future dose reference levels. This paper presents a set of patient dose values, in terms of air kerma area product (KAP) and entrance surface air kerma (ESAK), measured in a pediatric cardiac catheterization laboratory equipped with a biplane x-ray system with dynamic flat panel detectors. Cardiologists were properly trained in radiation protection. The study includes 137 patients aged between 10 days and 16 years who underwent diagnostic catheterizations or therapeutic procedures. Demographic data and technical details of the procedures were also gathered. The x-ray system was submitted to a quality control programme, including the calibration of the transmission ionization chamber. The age distribution of the patients was 47 for <1 year; 52 for 1-<5 years; 25 for 5-<10 years and 13 for 10-<16 years. Median values of KAP were 1.9, 2.9, 4.5 and 15.4 Gy cm(2) respectively for the four age bands. These KAP values increase by a factor of 8 when moving through the four age bands. The probability of a fatal cancer per fluoroscopically guided cardiac procedure is about 0.07%. Median values of ESAK for the four age bands were 46, 50, 56 and 163 mGy, which lie far below the threshold for deterministic effects on the skin. These dose values are lower than those published in previous papers.

  8. Therapeutic rationale for low dose doxepin in insomnia patients

    PubMed Central

    Katwala, Jigar; Kumar, Ananda K; Sejpal, Jaykumar J; Terrence, Marcelle; Mishra, Manish

    2013-01-01

    Histamine is an excitatory neurotransmitter in central nervous system. It plays an important role in the regulation of the sleep-wake cycle. Antidepressant with sleep-promoting effects, for example, doxepin, promotes sleep not through a sedative action but through resynchronisation of circadian cycle. The stimulation of the H1 receptor is thought to play an important role in mediating arousal. Doxepin has a high affinity for the H1 receptor, making it a selective H1 antagonist at low dose and it has been shown to display sedating properties. Compared to other sedative antidepressant, low dose doxepin is the only tricyclic drug which has been evaluated by well-designed, randomised, double blind, placebo controlled studies in both adult and elderly patients. Doxepin is not designated as controlled substance/unscheduled drugs and thus may be of special advantage to use in patients with a history of substance abuse. Hence, well-documented therapeutic efficacy, tolerability and lack of important adverse effects make the low dose doxepin as a unique, rational drug for the treatment of insomnia in adult and elderly patients.

  9. Fludarabine Allows Dose Reduction for Total Body Irradiation in Pediatric Hematopoietic Stem Cell Transplantation

    SciTech Connect

    Kornguth, David G. . E-mail: dkorngut@mdanderson.org; Mahajan, Anita; Woo, Shiao; Chan, Ka Wah; Antolak, John; Ha, Chul S.

    2007-07-15

    Purpose: To examine, in the setting of total body irradiation (TBI) for the preparation of pediatric hematopoietic stem cell transplantation (HSCT), whether TBI dose can be reduced without compromising the efficacy of a regimen consisting of fludarabine and radiotherapy; and whether there is any increased risk of pulmonary toxicity due to the radiosensitizing effect of fludarabine. Methods and Materials: A total of 52 pediatric patients with hematologic malignancies received TBI-based conditioning regimens in preparation for allogeneic HSCT. Twenty-three patients received 12 Gy in 4 daily fractions in combination with cyclophosphamide, either alone or with other chemotherapeutic and biologic agents. Twenty-nine patients received 9 Gy in 3 fractions in conjunction with fludarabine and melphalan. Clinical and radiation records were reviewed to determine engraftment, pulmonary toxicity (according to Radiation Therapy Oncology Group criteria), transplant-related mortality, recurrence of primary disease, and overall survival. Results: The two groups of patients had comparable pretransplant clinical characteristics. For the 12-Gy and 9-Gy regimens, the engraftment (89% and 93%; p = 0.82), freedom from life-threatening pulmonary events (65% and 79%; p = 0.33), freedom from relapse (60% and 73%; p = 0.24), and overall survival (26% and 47%; p = 0.09) were not statistically different. Conclusions: The addition of fludarabine and melphalan seems to allow the dose of TBI to be lowered to 9 Gy without loss of engraftment or antitumor efficacy.

  10. [Dyslipidemic patients with coronary cardiopathy. Effect of different doses of OMEGA-3 fatty acids on serum lipids and lipoproteins].

    PubMed

    Arteaga, A; Villanueva, C L; Skorin, C; Guasch, V; Solís de Ovando, F; Velasco, N; Acosta, A M; Leighton, F

    1993-06-01

    Twenty one male patients aged 35 to 70 years, with coronary artery disease and dislipidemia refractory to dietary treatment, were assigned to three parallel groups of 7 individuals each that received a supplemental dose of 2, 4 and 6 g/day of omega-3 fatty acids during 60 days. After a 30 days wash-out period and 60 of supplementation, subjects were weighed, a dietary survey was performed, serum levels of total cholesterol and triglycerides, the lipid content of serum lipoproteins and the content of EPA+DHA in plasma phospholipids were measured. A dose dependent increase in EPA+DHA content of phospholipids and no changes in weight or nutrient intake were observed during the supplementation period. With the 6 g dose, a significant reduction in total cholesterol, with a reduction in VLDL and increase in LDL cholesterol and a decline in VLDL triglycerides was observed. With the 4 g dose a reduction in total cholesterol at the expense of VLDL and HDL cholesterol and a reduction in VLDL triglycerides but no changes in total triglycerides was observed. No changes in serum lipids were observed with 2 g dose. In patients with type IIA hyperlipidemia, a significant positive correlation was observed between DHA+EPA content of plasma phospholipids and LDL cholesterol, this correlation was not observed in patients with IIB or IV phenotypes. It is concluded that omega-3 fatty acids are ineffective as the only treatment for dislipidemias refractory to diet.

  11. A patient-specific Monte Carlo dose-calculation method for photon beams.

    PubMed

    Wang, L; Chui, C S; Lovelock, M

    1998-06-01

    A patient-specific, CT-based, Monte Carlo dose-calculation method for photon beams has been developed to correctly account for inhomogeneity in the patient. The method employs the EGS4 system to sample the interaction of radiation in the medium. CT images are used to describe the patient geometry and to determine the density and atomic number in each voxel. The user code (MCPAT) provides the data describing the incident beams, and performs geometry checking and energy scoring in patient CT images. Several variance reduction techniques have been implemented to improve the computation efficiency. The method was verified with measured data and other calculations, both in homogeneous and inhomogeneous media. The method was also applied to a lung treatment, where significant differences in dose distributions, especially in the low-density region, were observed when compared with the results using an equivalent pathlength method. Comparison of the DVHs showed that the Monte Carlo calculated plan predicted an underdose of nearly 20% to the target, while the maximum doses to the cord and the heart were increased by 25% and 33%, respectively. These results suggested that the Monte Carlo method may have an impact on treatment designs, and also that it can be used as a benchmark to assess the accuracy of other dose calculation algorithms. The computation time for the lung case employing five 15-MV wedged beams, with an approximate field size of 13 X 13 cm and the dose grid size of 0.375 cm, was less than 14 h on a 175-MHz computer with a standard deviation of 1.5% in the high-dose region.

  12. PWR Facility Dose Modeling Using MCNP5 and the CADIS/ADVANTG Variance-Reduction Methodology

    SciTech Connect

    Blakeman, Edward D; Peplow, Douglas E.; Wagner, John C; Murphy, Brian D; Mueller, Don

    2007-09-01

    The feasibility of modeling a pressurized-water-reactor (PWR) facility and calculating dose rates at all locations within the containment and adjoining structures using MCNP5 with mesh tallies is presented. Calculations of dose rates resulting from neutron and photon sources from the reactor (operating and shut down for various periods) and the spent fuel pool, as well as for the photon source from the primary coolant loop, were all of interest. Identification of the PWR facility, development of the MCNP-based model and automation of the run process, calculation of the various sources, and development of methods for visually examining mesh tally files and extracting dose rates were all a significant part of the project. Advanced variance reduction, which was required because of the size of the model and the large amount of shielding, was performed via the CADIS/ADVANTG approach. This methodology uses an automatically generated three-dimensional discrete ordinates model to calculate adjoint fluxes from which MCNP weight windows and source bias parameters are generated. Investigative calculations were performed using a simple block model and a simplified full-scale model of the PWR containment, in which the adjoint source was placed in various regions. In general, it was shown that placement of the adjoint source on the periphery of the model provided adequate results for regions reasonably close to the source (e.g., within the containment structure for the reactor source). A modification to the CADIS/ADVANTG methodology was also studied in which a global adjoint source is weighted by the reciprocal of the dose response calculated by an earlier forward discrete ordinates calculation. This method showed improved results over those using the standard CADIS/ADVANTG approach, and its further investigation is recommended for future efforts.

  13. The dose of dialysis in hemodialysis patients: impact on nutrition.

    PubMed

    Schulman, Gerald

    2004-01-01

    Multiple lines of evidence have indicated that the dose of hemodialysis impacts upon patient outcome. Among these outcome measures, nutrition is inextricably linked to the adequacy of the treatment. All of the methods of determining dialysis adequacy are based on assessing the removal of toxic substances retained in renal failure, the majority of which are derivatives of protein metabolism. Urea kinetics, employing urea as a surrogate for quantifying the elimination of small molecular weight nitrogenous substances, is the method that has been most thoroughly validated to date as defining a dose range for thrice-weekly hemodialysis: Both inadequate and optimal levels of hemodialysis dose have been identified by prospective, randomized clinic trials utilizing Kt/V(urea) as the index of adequacy. The impact of urea kinetics on nutritional status during thrice-weekly hemodialysis is discussed. Recently, in an attempt to improve outcome beyond that achievable with thrice-weekly hemodialysis, alternative regimens, consisting of daily treatments, have received increasing interest. In order to compare the dose of hemodialysis associated with these regimens with conventional thrice-weekly regimens in terms of removal of small molecular weight substances, standard Kt/V(urea), a parameter that combines treatment dose with treatment frequency, and thus allows for various intermittent therapies to be compared to continuous therapy, must be used. In addition, membrane flux and middle molecule removal, factors that have not yet been well defined as parameters of adequacy during thrice-weekly regimens, may be shown to be important indices with longer hemodialysis treatments, particularly daily nocturnal hemodialysis. The impact that these alternative regimens have had on nutritional status in hemodialysis patients and how they compare to conventional therapy are important considerations.

  14. Relationship between radiation dose reduction and image quality change in photostimulable phosphor luminescence X-ray imaging systems

    PubMed Central

    Sakurai, T; Kawamata, R; Kozai, Y; Kaku, Y; Nakamura, K; Saito, M; Wakao, H; Kashima, I

    2010-01-01

    Objectives The aim of the study was to clarify the change in image quality upon X-ray dose reduction and to re-analyse the possibility of X-ray dose reduction in photostimulable phosphor luminescence (PSPL) X-ray imaging systems. In addition, the study attempted to verify the usefulness of multiobjective frequency processing (MFP) and flexible noise control (FNC) for X-ray dose reduction. Methods Three PSPL X-ray imaging systems were used in this study. Modulation transfer function (MTF), noise equivalent number of quanta (NEQ) and detective quantum efficiency (DQE) were evaluated to compare the basic physical performance of each system. Subjective visual evaluation of diagnostic ability for normal anatomical structures was performed. The NEQ, DQE and diagnostic ability were evaluated at base X-ray dose, and 1/3, 1/10 and 1/20 of the base X-ray dose. Results The MTF of the systems did not differ significantly. The NEQ and DQE did not necessarily depend on the pixel size of the system. The images from all three systems had a higher diagnostic utility compared with conventional film images at the base and 1/3 X-ray doses. The subjective image quality was better at the base X-ray dose than at 1/3 of the base dose in all systems. The MFP and FNC-processed images had a higher diagnostic utility than the images without MFP and FNC. Conclusions The use of PSPL imaging systems may allow a reduction in the X-ray dose to one-third of that required for conventional film. It is suggested that MFP and FNC are useful for radiation dose reduction. PMID:20395461

  15. Dose reduction by moving a region of interest (ROI) beam attenuator to follow a moving object of interest

    NASA Astrophysics Data System (ADS)

    Panse, Ashish S.; Swetadri Vasan, S. N.; Jain, A.; Bednarek, D. R.; Rudin, S.

    2012-03-01

    Region-of-interest (ROI) fluoroscopy takes advantage of the fact that most neurovascular interventional activity is performed in only a small portion of an x-ray imaging field of view (FOV). The ROI beam filter is an attenuating material that reduces patient dose in the area peripheral to the object of interest. This project explores a method of moving the beam-attenuator aperture with the object of interest such that it always remains in the ROI. In this study, the ROI attenuator, which reduces the dose by 80% in the peripheral region, is mounted on a linear stage placed near the xray tube. Fluoroscopy is performed using the Microangiographic Fluoroscope (MAF) which is a high-resolution, CCD-based x-ray detector. A stainless-steel stent is selected as the object of interest, and is moved across the FOV and localized using an object-detection algorithm available in the IMAQ Vision package of LabVIEW. The ROI is moved to follow the stent motion. The pixel intensities are equalized in both FOV regions and an adaptive temporal filter dependent on the motion of the object of interest is implemented inside the ROI. With a temporal filter weight of 5% for the current image in the peripheral region, the SNR measured is 47.8. The weights inside the ROI vary between 10% and 33% with a measured SNR of 57.9 and 35.3 when the object is stationary and moving, respectively. This method allows patient dose reduction as well as maintenance of superior image quality in the ROI while tracking the object.

  16. Dose reduction by moving a region of interest (ROI) beam attenuator to follow a moving object of interest.

    PubMed

    Panse, Ashish S; Swetadri Vasan, S N; Jain, A; Bednarek, D R; Rudin, S

    2012-01-01

    Region-of-interest (ROI) fluoroscopy takes advantage of the fact that most neurovascular interventional activity is performed in only a small portion of an x-ray imaging field of view (FOV). The ROI beam filter is an attenuating material that reduces patient dose in the area peripheral to the object of interest. This project explores a method of moving the beam-attenuator aperture with the object of interest such that it always remains in the ROI. In this study, the ROI attenuator, which reduces the dose by 80% in the peripheral region, is mounted on a linear stage placed near the x-ray tube. Fluoroscopy is performed using the Microangiographic Fluoroscope (MAF) which is a high-resolution, CCD-based x-ray detector. A stainless-steel stent is selected as the object of interest, and is moved across the FOV and localized using an object-detection algorithm available in the IMAQ Vision package of LabVIEW. The ROI is moved to follow the stent motion. The pixel intensities are equalized in both FOV regions and an adaptive temporal filter dependent on the motion of the object of interest is implemented inside the ROI. With a temporal filter weight of 5% for the current image in the peripheral region, the SNR measured is 47.8. The weights inside the ROI vary between 10% and 33% with a measured SNR of 57.9 and 35.3 when the object is stationary and moving, respectively. This method allows patient dose reduction as well as maintenance of superior image quality in the ROI while tracking the object.

  17. High-dose inhaled corticosteroids or addition of theophylline in patients with poorly controlled asthma?

    PubMed

    Celis, Pilar; Rada, Gabriel

    2015-08-19

    There are several management strategies for patients with poorly controlled asthma despite usual treatment. Increasing doses of inhaled corticosteroids or adding theophylline are among the therapeutic alternatives. However, the latter is associated with important adverse effects. Searching in Epistemonikos database, which is maintained by screening 30 databases, we identified only one systematic review including four pertinent randomized controlled trials. We combined the evidence using meta-analysis and generated a summary of findings following the GRADE approach. We concluded it is not clear whether theophylline or high-dose inhaled corticosteroids constitute a better alternative for symptomatic control or reduction in exacerbations in poorly controlled asthmatic patients because the certainty of the evidence is very low.

  18. Estimated UV doses to psoriasis patients during climate therapy at Gran Canaria in March 2006

    NASA Astrophysics Data System (ADS)

    Nilsen, L. T. N.; Søyland, E.; Krogstad, A. L.

    2008-01-01

    Psoriasis is a chronic inflammatory disease involving about 2-3% of the Norwegian population. Sun exposure has a positive effect on most psoriasis lesions, but ultraviolet (UV) radiation also causes a direct DNA damage in the skin cells and comprises a carcinogenic potential. UV exposure on the skin causes a local as well as a systemic immune suppressive effect, but the relation between sun exposure and these biological effects is not well known. In March 2006 a study was carried out to investigate possible therapeutic outcome mechanisms in 20 psoriasis patients receiving climate therapy at Gran Canaria. This paper presents estimates of their individual skin UV-doses based on UV measurements and the patients' diaries with information on time spent in the sun. On the first day of exposure the patients received on average 5.1 Standard Erythema Doses (SED: median=4.0 SED, range 2.6-10.3 SED) estimated to the skin. During the 15 days study they received 165.8 SED (range 104.3-210.1 SED). The reduction in PASI score was 72.8% on average, but there was no obvious relation between the improvement and the UV dose. The UV doses were higher than those found from climate therapy studies at other locations. It seems beneficial to use more strict exposure schedules that consider the available UV irradiance, depending on time of the day, time of the year and weather conditions.

  19. High dose tigecycline in critically ill patients with severe infections due to multidrug-resistant bacteria

    PubMed Central

    2014-01-01

    Introduction The high incidence of multidrug-resistant (MDR) bacteria among patients admitted to ICUs has determined an increase of tigecycline (TGC) use for the treatment of severe infections. Many concerns have been raised about the efficacy of this molecule and increased dosages have been proposed. Our purpose is to investigate TGC safety and efficacy at higher than standard doses. Methods We conducted a retrospective study of prospectively collected data in the ICU of a teaching hospital in Rome. Data from all patients treated with TGC for a microbiologically confirmed infection were analyzed. The safety profile and efficacy of high dosing regimen use were investigated. Results Over the study period, 54 patients (pts) received TGC at a standard dose (SD group: 50 mg every 12 hours) and 46 at a high dose (HD group: 100 mg every 12 hours). Carbapenem-resistant Acinetobacter.baumannii (blaOXA-58 and blaOXA-23 genes) and Klebsiella pneumoniae (blaKPC-3 gene) were the main isolated pathogens (n = 79). There were no patients requiring TGC discontinuation or dose reduction because of adverse events. In the ventilation-associated pneumonia population (VAP) subgroup (63 patients: 30 received SD and 33 HD), the only independent predictor of clinical cure was the use of high tigecycline dose (odds ratio (OR) 6.25; 95% confidence interval (CI) 1.59 to 24.57; P = 0.009) whilst initial inadequate antimicrobial treatment (IIAT) (OR 0.18; 95% CI 0.05 to 0.68; P = 0.01) and higher Sequential Organ Failure Assessment (SOFA) score (OR 0.66; 95% CI 0.51 to 0.87; P = 0.003) were independently associated with clinical failure. Conclusions TGC was well tolerated at a higher than standard dose in a cohort of critically ill patients with severe infections. In the VAP subgroup the high-dose regimen was associated with better outcomes than conventional administration due to Gram-negative MDR bacteria. PMID:24887101

  20. Dosing of antibiotics in critically ill patients undergoing renal replacement therapy.

    PubMed

    Kielstein, Jan T; Burkhardt, Olaf

    2011-12-01

    On September 11, 1945 Maria Schafstaat was the first patient who successfully underwent a dialysis treatment for acute kidney injury (AKI), formerly known as acute renal failure. Since then, the number of patients with AKI is increasing worldwide. Today AKI is generally one feature of a multiple organ dysfunction syndrome (MODS), which develops in response to major surgery, cardiogenic shock or sepsis. Several clinical studies have shown that early and appropriate antibiotic therapy in those patients is of utter importance, yet it remains one of the most difficult challenges to meet. Even in critically ill patients with conserved renal function a myriad of pathophysiological changes, resulting in increased volume of distribution, decreased protein binding and altered hepatic drug clearance, makes appropriate antibiotic dosin difficult. Adequate pharmacotherapy, i.e. dose of anti-infective agens is becoming even more complicated if it has to be tailored to counteract their removal by different modes and intensities of renal replacement therapy. This review summarizes our sparse knowledge about pharmacokinetic studies and dosing recommendations of drugs in patients with AKI undergoing continuous renal replacement therapies (CRRTs) such as continuous venovenous hemofiltration (CVVH) as well as extended dialysis (ED), an increasingly used method to treat patients with AKI in the intensive care setting. We reflect on failure of several large prospective controlled studies to show a survival benefit of higher doses of renal replacement therapy, a finding that might be caused by the fact that we still adhere to dosing guidelines for antibiotics which are at best ineffectual but might also lead to potentially dangerous underdosing of these life saving drugs. Lastly we address possible strategies to overcome the lack of knowledge, the lack of data and the lack of interest in this important area of critical care medicine. Improvement of clinical outcomes and reduction of

  1. Assessing patient dose in interventional fluoroscopy using patient-dependent hybrid phantoms

    NASA Astrophysics Data System (ADS)

    Johnson, Perry Barnett

    Interventional fluoroscopy uses ionizing radiation to guide small instruments through blood vessels or other body pathways to sites of clinical interest. The technique represents a tremendous advantage over invasive surgical procedures, as it requires only a small incision, thus reducing the risk of infection and providing for shorter recovery times. The growing use and increasing complexity of interventional procedures, however, has resulted in public health concerns regarding radiation exposures, particularly with respect to localized skin dose. Tracking and documenting patient-specific skin and internal organ dose has been specifically identified for interventional fluoroscopy where extended irradiation times, multiple projections, and repeat procedures can lead to some of the largest doses encountered in radiology. Furthermore, inprocedure knowledge of localized skin doses can be of significant clinical importance to managing patient risk and in training radiology residents. In this dissertation, a framework is presented for monitoring the radiation dose delivered to patients undergoing interventional procedures. The framework is built around two key points, developing better anthropomorphic models, and designing clinically relevant software systems for dose estimation. To begin, a library of 50 hybrid patient-dependent computational phantoms was developed based on the UF hybrid male and female reference phantoms. These phantoms represent a different type of anthropomorphic model whereby anthropometric parameters from an individual patient are used during phantom selection. The patient-dependent library was first validated and then used in two patient-phantom matching studies focused on cumulative organ and local skin dose. In terms of organ dose, patient-phantom matching was shown most beneficial for estimating the dose to large patients where error associated with soft tissue attenuation differences could be minimized. For small patients, inherent difference

  2. Pharmacokinetic Dashboard-Recommended Dosing Is Different than Standard of Care Dosing in Infliximab-Treated Pediatric IBD Patients.

    PubMed

    Dubinsky, Marla C; Phan, Becky L; Singh, Namita; Rabizadeh, Shervin; Mould, Diane R

    2017-01-01

    Standard of care (SOC; combination of 5-10 mg/kg and an interval every 6-8 weeks) dosing of infliximab (IFX) is associated with significant loss of response. Dashboards using covariates that influence IFX pharmacokinetics (PK) may be a more precise way of optimizing anti-TNF dosing. We tested a prototype dashboard to compare forecasted dosing regimens with actual administered regimens and SOC. Fifty IBD patients completing IFX induction were monitored during maintenance (weeks 14-54). Clinical and laboratory data were collected at each infusion; serum was analyzed for IFX concentrations and anti-drug antibodies (ADA) at weeks 14 and 54 (Prometheus Labs, San Diego). Dosing was blinded to PK data. Dashboard-based assessments were conducted on de-identified clinical, laboratory, and PK data. Bayesian algorithms were used to forecast individualized troughs and determine optimal dosing to maintain target trough concentrations (3 μg/mL). Dashboard forecasted dosing post-week 14 was compared to actual administered dose and frequency and SOC. Using week 14 clinical data only, the dashboard recommended either a dose or an interval change (<0.5 mg/kg or <1 week difference) in 43/50 patients; only 44% recommended to have SOC dosing. When IFX14 concentration and ADA status were added to clinical data, dose and/or interval changes based on actual dosing were recommended in 48/50 (96%) patients; SOC dosing was recommended in only 11/50 (22%). Dashboard recommended SOC IFX dosing in a minority of patients. Dashboards will be an important tool to individualize IFX dosing to improve treatment durability.

  3. Quantification and reduction of peripheral dose from leakage radiation on Siemens Primus accelerators in electron therapy mode.

    PubMed

    Yeboah, Collins; Karotki, Alex; Hunt, Dylan; Holly, Rick

    2010-06-15

    In this work, leakage radiation from EA200 series electron applicators on Siemens Primus accelerators is quantified, and its penetration ability in water and/or the shielding material Xenolite-NL established. Initially, measurement of leakage from 10 x 10 - 25 x 25 cm2 applicators was performed as a function of height along applicator and of lateral distance from applicator body. Relative to central-axis ionization maximum in solid water, the maximum leakage in air observed with a cylindrical ion chamber with 1 cm solid water buildup cap at a lateral distance of 2 cm from the front and right sidewalls of applicators were 17% and 14%, respectively; these maxima were recorded for 18 MeV electron beams and applicator sizes of >or=20 x 20 cm2. In the patient plane, the applicator leakage gave rise to a broad peripheral dose off-axis distance peak that shifted closer to the field edge as the electron energy increases. The maximum peripheral dose from normally incident primary electron beams at a depth of 1 cm in a water phantom was observed to be equal to 5% of the central-axis dose maximum and as high as 9% for obliquely incident beams with angles of obliquity dose curves showed that the "practical range" of the leakage electrons in water varies from approximately 1.4 to 5.7 cm as the primary electron beam energy is raised from 6 to 18 MeV. Next, transmission measurements of leakage radiation through the shielding material Xenolite-NL showed a 4 mm thick sheet of this material is required to attenuate the leakage from 9 MeV beams by two-thirds, and that for every additional 3 MeV increase in the primary electron beam energy, an additional Xenolite-NL thickness of roughly 2 mm is needed to achieve the aforementioned attenuation level. Finally, attachment of a 1 mm thick sheet of lead to the outer surface of applicator sidewalls resulted in a reduction of the peripheral dose by up to 80% and 74% for 9 and 18MeV beams

  4. Dose reduction assessment in dynamic CT myocardial perfusion imaging in a porcine balloon-induced-ischemia model

    NASA Astrophysics Data System (ADS)

    Fahmi, Rachid; Eck, Brendan L.; Vembar, Mani; Bezerra, Hiram G.; Wilson, David L.

    2014-03-01

    We investigated the use of an advanced hybrid iterative reconstruction (IR) technique (iDose4, Philips Health- care) for low dose dynamic myocardial CT perfusion (CTP) imaging. A porcine model was created to mimic coronary stenosis through partial occlusion of the left anterior descending (LAD) artery with a balloon catheter. The severity of LAD occlusion was adjusted with FFR measurements. Dynamic CT images were acquired at end-systole (45% R-R) using a multi-detector CT (MDCT) scanner. Various corrections were applied to the acquired scans to reduce motion and imaging artifacts. Absolute myocardial blood flow (MBF) was computed with a deconvolution-based approach using singular value decomposition (SVD). We compared a high and a low dose radiation protocol corresponding to two different tube-voltage/tube-current combinations (80kV p/100mAs and 120kV p/150mAs). The corresponding radiation doses for these protocols are 7.8mSv and 34.3mSV , respectively. The images were reconstructed using conventional FBP and three noise-reduction strengths of the IR method, iDose. Flow contrast-to-noise ratio, CNRf, as obtained from MBF maps, was used to quantitatively evaluate the effect of reconstruction on contrast between normal and ischemic myocardial tissue. Preliminary results showed that the use of iDose to reconstruct low dose images provide better or comparable CNRf to that of high dose images reconstructed with FBP, suggesting significant dose savings. CNRf was improved with the three used levels of iDose compared to FBP for both protocols. When using the entire 4D dynamic sequence for MBF computation, a 77% dose reduction was achieved, while considering only half the scans (i.e., every other heart cycle) allowed even further dose reduction while maintaining relatively higher CNRf.

  5. Calculation of patient effective dose and scattered dose for dental mobile fluoroscopic equipment: application of the Monte Carlo simulation.

    PubMed

    Lee, Boram; Lee, Jungseok; Kang, Sangwon; Cho, Hyelim; Shin, Gwisoon; Lee, Jeong-Woo; Choi, Jonghak

    2013-01-01

    The objective of this study was to evaluate the patient effective dose and scattered dose from recently developed dental mobile equipment in Korea. The MCNPX 2.6 (Los Alamos National Laboratory, USA) was used in a Monte Carlo simulation to calculate both the effective and scattered doses. The MCNPX code was constructed identically as in the general use of equipment and the effective dose and scattered dose were calculated using the KTMAN-2 digital phantom. The effective dose was calculated as 906 μSv. The equivalent doses per organ were calculated via the MCNPX code, and were 32 174 and 19 μSv in the salivary gland and oesophagus, respectively. The scattered dose of 22.5-32.6 μSv of the tube side at 25 cm from the centre in anterior and posterior planes was measured as 1.4-3 times higher than the detector side of 10.5-16.0 μSv.

  6. Cotrimoxazole plasma levels, dialyzer clearance and total removal by extended dialysis in a patient with acute kidney injury: risk of under-dosing using current dosing recommendations

    PubMed Central

    2013-01-01

    Background Dosing of antibiotics in critically ill patients is challenging. It becomes even more difficult if renal or hepatic impairment ensue. Modern means of renal replacement therapy are capable of removing antibiotics to a higher rate than decades ago, leaving clinicians with a high degree of uncertainty concerning the dose of antibiotics in this patient population. Cotrimoxazole, a combination of trimethoprim (TMP) and sulfamethoxazole (SMX) is frequently used in the treatment of several infections including Pneumocystis jirovecii pneumonia (PCP). Case presentation Here we describe a patient with acute kidney injury in which we investigated the TMP and SMX levels during the course of an ICU stay. Cotrimoxazole was administered every six hours i.v. in a dose of TMP/SMX 15/75 mg/kg/day. Extended dialysis was performed with a high-flux dialyzer. Blood samples, as well as pre- and postdialyzer samples and aliquots of the collected spent dialysate were collected. Observed peak concentrations (Cmax) were 7.51 mg/l for TMP and 80.80 mg/l for SMX. Decline of blood levels during extended dialysis (TMP 64%; SMX 84%) was mainly due to removal by the dialysis procedure, illustrated by the high dialyzer clearances (median of 4 extended dialysis sessions: TMP 94.0 / SMX 51.0 ml/min), as well as by the absolute amount of both substances in the collected spent dialysate (median of 6 extended dialysis sessions: TMP 556 mg / SMX 130 mg). Within the limitation of a case report our data from 4 consecutive extended dialysis sessions suggest that this procedure substantially removes both TMP and SMX. Conclusions Dose reduction, which is usually advocated in patients with acute kidney injury under renal replacement therapy, might lead to significant under-dosing. Pharmacokinetic studies for TMP/SMX dosing in this patient population are necessary to allow adequate dosing. PMID:23551893

  7. Radiation dose reduction in computed tomography (CT) using a new implementation of wavelet denoising in low tube current acquisitions

    NASA Astrophysics Data System (ADS)

    Tao, Yinghua; Brunner, Stephen; Tang, Jie; Speidel, Michael; Rowley, Howard; VanLysel, Michael; Chen, Guang-Hong

    2011-03-01

    Radiation dose reduction remains at the forefront of research in computed tomography. X-ray tube parameters such as tube current can be lowered to reduce dose; however, images become prohibitively noisy when the tube current is too low. Wavelet denoising is one of many noise reduction techniques. However, traditional wavelet techniques have the tendency to create an artificial noise texture, due to the nonuniform denoising across the image, which is undesirable from a diagnostic perspective. This work presents a new implementation of wavelet denoising that is able to achieve noise reduction, while still preserving spatial resolution. Further, the proposed method has the potential to improve those unnatural noise textures. The technique was tested on both phantom and animal datasets (Catphan phantom and timeresolved swine heart scan) acquired on a GE Discovery VCT scanner. A number of tube currents were used to investigate the potential for dose reduction.

  8. Intravenous heparin dosing strategy in hospitalized patients with atrial dysrhythmias.

    PubMed

    Roswell, Robert O; Greet, Brian; Shah, Sunny; Bernard, Samuel; Milin, Alexandra; Lobach, Iryna; Guo, Yu; Radford, Martha J; Berger, Jeffrey S

    2016-08-01

    Patients with non-valvular atrial fibrillation (AF) have an elevated stroke risk that is 2-7 times greater than in those without AF. Intravenous unfractionated heparin (UFH) is commonly used for hospitalized patients with atrial fibrillation and atrial flutter (AFL) to prevent stroke. Dosing strategies exist for intravenous anticoagulation in patients with acute coronary syndromes and venous thromboembolic diseases, but there are no data to guide providers on a dosing strategy for intravenous anticoagulation in patients with AF/AFL. 996 hospitalized patients with AF/AFL on UFH were evaluated. Bolus dosing and initial infusion rates of UFH were recorded along with rates of stroke, thromboemobolic events, and bleeding events as defined by the International Society on Thrombosis and Haemostasis criteria. Among 226 patients included in the analysis, 76 bleeding events occurred. Using linear regression analysis, initial rates of heparin infusion ranging from 9.7 to 11.8 units/kilogram/hour (U/kg/h) resulted in activated partial thromboplastin times that were within therapeutic range. The median initial infusion rate in patients with bleeding was 13.3 U/kg/h, while in those without bleeding it was 11.4 U/kg/h; p = 0.012. An initial infusion rate >11.0 U/kg/h yielded an OR 1.95 (1.06-3.59); p = 0.03 for any bleeding event. Using IV heparin boluses neither increased the probability of attaining a therapeutic aPTT (56.1 vs 56.3 %; p = 0.99) nor did it significantly increase bleeding events in the study (35.7 vs 31.3 %; p = 0.48). The results suggest that higher initial rates of heparin are associated with increased bleeding risk. From this dataset, initial heparin infusion rates of 9.7-11.0 U/kg/h without a bolus can result in therapeutic levels of anticoagulation in hospitalized patients with AF/AFL without increasing the risk of bleeding.

  9. Balancing dose and image registration accuracy for cone beam tomosynthesis (CBTS) for breast patient setup

    SciTech Connect

    Winey, B. A.; Zygmanski, P.; Cormack, R. A.; Lyatskaya, Y.

    2010-08-15

    Purpose: To balance dose reduction and image registration accuracy in breast setup imaging. In particular, the authors demonstrate the relationship between scan angle and dose delivery for cone beam tomosynthesis (CBTS) when employed for setup verification of breast cancer patients with surgical clips. Methods: The dose measurements were performed in a female torso phantom for varying scan angles of CBTS. Setup accuracy was measured using three registration methods: Clip centroid localization accuracy and the accuracy of two semiautomatic registration algorithms. The dose to the organs outside of the ipsilateral breast and registration accuracy information were compared to determine the optimal scan angle for CBTS for breast patient setup verification. Isocenter positions at the center of the patient and at the breast-chest wall interface were considered. Results: Image registration accuracy was within 1 mm for the CBTS scan angles {theta} above 20 deg. for some scenarios and as large as 80 deg. for the worst case, depending on the imaged breast and registration algorithm. Registration accuracy was highest based on clip centroid localization. For left and right breast imaging with the isocenter at the chest wall, the dose to the contralateral side of the patient was very low (<0.5 cGy) for all scan angles considered. For central isocenter location, the optimal scan angles were 30 deg. - 50 deg. for the left breast imaging and 40 deg. - 50 deg. for the right breast imaging, with the difference due to the geometric asymmetry of the current clinical imaging system. Conclusions: The optimal scan angles for CBTS imaging were found to be between 10 deg. and 50 deg., depending on the isocenter location and ipsilateral breast. Use of the isocenter at the breast-chest wall locations always resulted in greater accuracy of image registration (<1 mm) at smaller angles (10 deg. - 20 deg.) and at lower doses (<0.1 cGy) to the contralateral organs. For chest wall isocenters

  10. Absorbed photon dose measurement and calculation for some patient organs examined by computed tomography

    NASA Astrophysics Data System (ADS)

    Shousha, Hany A.

    Patient doses from computed tomography (CT) examinations are usually expressed in terms of dose index, organ doses, and effective dose. The CT dose index (CTDI) can be measured free-in-air or in a CT dosimetry phantom. Organ doses can be measured directly in anthropomorphic Rando phantoms using thermoluminescent detectors. Organ doses can also be calculated by the Monte Carlo method utilizing measured CTDI values. In this work, organ doses were assessed for three main CT examinations: head, chest, and abdomen, using the different mentioned methods. Results of directly measured doses were compared with calculated doses for different organs in the study, and also compared with published international studies.

  11. Sci—Fri AM: Mountain — 02: A comparison of dose reduction methods on image quality for cone beam CT

    SciTech Connect

    Webb, R; Buckley, LA

    2014-08-15

    Modern radiotherapy uses highly conformai dose distributions and therefore relies on daily image guidance for accurate patient positioning. Kilovoltage cone beam CT is one technique that is routinely used for patient set-up and results in a high dose to the patient relative to planar imaging techniques. This study uses an Elekta Synergy linac equipped with XVI cone beam CT to investigate the impact of various imaging parameters on dose and image quality. Dose and image quality are assessed as functions of x-ray tube voltage, tube current and the number of projections in the scan. In each case, the dose measurements confirm that as each parameter increases the dose increases. The assessment of high contrast resolution shows little dependence on changes to the image technique. However, low contrast visibility suggests a trade off between dose and image quality. Particularly for changes in tube potential, the dose increases much faster as a function of voltage than the corresponding increase in low contrast image quality. This suggests using moderate values of the peak tube voltage (100 – 120 kVp) since higher values result in significant dose increases with little gain in image quality. Measurements also indicate that increasing tube current achieves the greatest degree of improvement in the low contrast visibility. The results of this study highlight the need to establish careful imaging protocols to limit dose to the patient and to limit changes to the imaging parameters to those cases where there is a clear clinical requirement for improved image quality.

  12. Dose-dependent valproate-induced alopecia in patients with mental disorders.

    PubMed

    Tomita, Takashi; Goto, Hidekazu; Yoshida, Tadashi; Tanaka, Katsuya; Sumiya, Kenji; Kohda, Yukinao

    2015-01-01

    Drug-induced hair loss may occur as a side effect in patients treated with valproate. However, few studies have reported a relationship between the blood levels of valproate and the occurrence of hair loss. We report three cases of alopecia that occurred in patients who received sodium valproate for mental disorders. In all three cases, alopecia appeared after long-term valproate exposure with a plasma concentration of 100 µg/ml approximately. However, the alopecia resolved in all cases after dose reduction or treatment discontinuation. Therefore, alopecia may develop in patients with chronic exposure to high plasma concentrations of valproate. Based on these findings, we believe that patients with high plasma concentrations of valproate should be closely monitored for the occurrence of side effects, particularly alopecia.

  13. SU-C-18C-06: Radiation Dose Reduction in Body Interventional Radiology: Clinical Results Utilizing a New Imaging Acquisition and Processing Platform

    SciTech Connect

    Kohlbrenner, R; Kolli, KP; Taylor, A; Kohi, M; Fidelman, N; LaBerge, J; Kerlan, R; Gould, R

    2014-06-01

    Purpose: To quantify the patient radiation dose reduction achieved during transarterial chemoembolization (TACE) procedures performed in a body interventional radiology suite equipped with the Philips Allura Clarity imaging acquisition and processing platform, compared to TACE procedures performed in the same suite equipped with the Philips Allura Xper platform. Methods: Total fluoroscopy time, cumulative dose area product, and cumulative air kerma were recorded for the first 25 TACE procedures performed to treat hepatocellular carcinoma (HCC) in a Philips body interventional radiology suite equipped with Philips Allura Clarity. The same data were collected for the prior 85 TACE procedures performed to treat HCC in the same suite equipped with Philips Allura Xper. Mean values from these cohorts were compared using two-tailed t tests. Results: Following installation of the Philips Allura Clarity platform, a 42.8% reduction in mean cumulative dose area product (3033.2 versus 1733.6 mGycm∧2, p < 0.0001) and a 31.2% reduction in mean cumulative air kerma (1445.4 versus 994.2 mGy, p < 0.001) was achieved compared to similar procedures performed in the same suite equipped with the Philips Allura Xper platform. Mean total fluoroscopy time was not significantly different between the two cohorts (1679.3 versus 1791.3 seconds, p = 0.41). Conclusion: This study demonstrates a significant patient radiation dose reduction during TACE procedures performed to treat HCC after a body interventional radiology suite was converted to the Philips Allura Clarity platform from the Philips Allura Xper platform. Future work will focus on evaluation of patient dose reduction in a larger cohort of patients across a broader range of procedures and in specific populations, including obese patients and pediatric patients, and comparison of image quality between the two platforms. Funding for this study was provided by Philips Healthcare, with 5% salary support provided to authors K. Pallav

  14. Stimulant Reduction Intervention using Dosed Exercise (STRIDE) - CTN 0037: Study protocol for a randomized controlled trial

    PubMed Central

    2011-01-01

    Background There is a need for novel approaches to the treatment of stimulant abuse and dependence. Clinical data examining the use of exercise as a treatment for the abuse of nicotine, alcohol, and other substances suggest that exercise may be a beneficial treatment for stimulant abuse, with direct effects on decreased use and craving. In addition, exercise has the potential to improve other health domains that may be adversely affected by stimulant use or its treatment, such as sleep disturbance, cognitive function, mood, weight gain, quality of life, and anhedonia, since it has been shown to improve many of these domains in a number of other clinical disorders. Furthermore, neurobiological evidence provides plausible mechanisms by which exercise could positively affect treatment outcomes. The current manuscript presents the rationale, design considerations, and study design of the National Institute on Drug Abuse (NIDA) Clinical Trials Network (CTN) CTN-0037 Stimulant Reduction Intervention using Dosed Exercise (STRIDE) study. Methods/Design STRIDE is a multisite randomized clinical trial that compares exercise to health education as potential treatments for stimulant abuse or dependence. This study will evaluate individuals diagnosed with stimulant abuse or dependence who are receiving treatment in a residential setting. Three hundred and thirty eligible and interested participants who provide informed consent will be randomized to one of two treatment arms: Vigorous Intensity High Dose Exercise Augmentation (DEI) or Health Education Intervention Augmentation (HEI). Both groups will receive TAU (i.e., usual care). The treatment arms are structured such that the quantity of visits is similar to allow for equivalent contact between groups. In both arms, participants will begin with supervised sessions 3 times per week during the 12-week acute phase of the study. Supervised sessions will be conducted as one-on-one (i.e., individual) sessions, although other

  15. Patients who do not respond to the "usual" dose: why Terry fell off the dose-response curve.

    PubMed

    Preskorn, Sheldon H

    2009-11-01

    Clinical trials are aimed at determining what happens in the "usual" patient; however, clinicians are interested in what happens in their patients even if they are not usual. The usual dose-response relationship is determined as part of the drug development process required for approval of a new drug. However, clinicians are likely to encounter patients who "fall off" the usual dose-response curve because they are either sensitive or resistant to the beneficial (efficacy) or adverse effects of a drug. This column is the first in a series that will examine why specific patients fall off the usual dose-response curve and how clinicians can manage such patients when they encounter them. This column discusses what a dose-response curve is, how it is determined, and why it is clinically important.

  16. Recombinant human erythropoietin therapy in critically ill patients: a dose-response study [ISRCTN48523317

    PubMed Central

    Georgopoulos, Dimitris; Matamis, Dimitris; Routsi, Christina; Michalopoulos, Argiris; Maggina, Nina; Dimopoulos, George; Zakynthinos, Epaminondas; Nakos, George; Thomopoulos, George; Mandragos, Kostas; Maniatis, Alice

    2005-01-01

    Introduction The aim of this study was to assess the efficacy of two dosing schedules of recombinant human erythropoietin (rHuEPO) in increasing haematocrit (Hct) and haemoglobin (Hb) and reducing exposure to allogeneic red blood cell (RBC) transfusion in critically ill patients. Method This was a prospective, randomized, multicentre trial. A total of 13 intensive care units participated, and a total of 148 patients who met eligibility criteria were enrolled. Patients were randomly assigned to receive intravenous iron saccharate alone (control group), intravenous iron saccharate and subcutaneous rHuEPO 40,000 units once per week (group A), or intravenous iron saccharate and subcutaneous rHuEPO 40,000 units three times per week (group B). rHuEPO was given for a minimum of 2 weeks or until discharge from the intensive care unit or death. The maximum duration of therapy was 3 weeks. Results The cumulative number of RBC units transfused, the average numbers of RBC units transfused per patient and per transfused patient, the average volume of RBCs transfused per day, and the percentage of transfused patients were significantly higher in the control group than in groups A and B. No significant difference was observed between group A and B. The mean increases in Hct and Hb from baseline to final measurement were significantly greater in group B than in the control group. The mean increase in Hct was significantly greater in group B than in group A. The mean increase in Hct in group A was significantly greater than that in control individuals, whereas the mean increase in Hb did not differ significantly between the control group and group A. Conclusion Administration of rHuEPO to critically ill patients significantly reduced the need for RBC transfusion. The magnitude of the reduction did not differ between the two dosing schedules, although there was a dose response for Hct and Hb to rHuEPO in these patients. PMID:16277712

  17. Single-dose pharmacokinetics of intravenous sulbactam in pediatric patients.

    PubMed

    Schaad, U B; Guenin, K; Straehl, P

    1986-01-01

    The pharmacokinetics of intravenously administered sulbactam were studied in 17 pediatric patients two to 14 years of age. Single doses of 12.5 or 25 mg/kg were infused over 3 min, and in previously healthy children, mean peak plasma concentrations 5 min after dosing were 71 and 163 micrograms/ml, respectively. Noncompartmental and compartmental calculations resulted in similar pharmacokinetic parameters. Linear pharmacokinetics were found in the concentration range studied. The mean terminal-phase half-life was 1.75 hr, the mean total plasma clearance was 180 ml/min per 1.73 m2, and the mean apparent volume of distribution was 340 ml/kg. Approximately 70%-80% of an intravenous dose was excreted unchanged in the urine. In children with cystic fibrosis, both total plasma clearance and apparent volume of distribution were significantly increased. The data support the intravenous administration of 12.5-25 mg of sulbactam/kg every 6 to 8 hr for assessing the adequacy of this drug as an adjunct to beta-lactam therapy for various bacterial infections in children.

  18. Moving back: The radiation dose received from lumbar spine quantitative fluoroscopy compared to lumbar spine radiographs with suggestions for dose reduction

    PubMed Central

    Mellor, F.E.; Thomas, P.; Breen, A.

    2014-01-01

    Purpose Quantitative fluoroscopy is an emerging technology for assessing continuous inter-vertebral motion in the lumbar spine, but information on radiation dose is not yet available. The purposes of this study were to compare the radiation dose from quantitative fluoroscopy of the lumbar spine with lumbar spine radiographs, and identify opportunities for dose reduction in quantitative fluoroscopy. Methods Internationally reported dose area product (DAP) and effective dose data for lumbar spine radiographs were compared with the same for quantitative fluoroscopy and with data from a local hospital for functional radiographs (weight bearing AP, lateral, and/or flexion and extension) (n = 27). The effects of procedure time, age, weight, height and body mass index on the fluoroscopy dose were determined by multiple linear regression using SPSS v19 software (IBM Corp., Armonck, NY, USA). Results and conclusion The effective dose (and therefore the estimated risk) for quantitative fluoroscopy is 0.561 mSv which is lower than in most published data for lumbar spine radiography. The dose area product (DAP) for sagittal (flexion + extension) quantitative fluoroscopy is 3.94 Gy cm2 which is lower than local data for two view (flexion and extension) functional radiographs (4.25 Gy cm2), and combined coronal and sagittal dose from quantitative fluoroscopy (6.13 Gy cm2) is lower than for four view functional radiography (7.34 Gy cm2). Conversely DAP for coronal and sagittal quantitative fluoroscopy combined (6.13 Gy cm2) is higher than that published for both lumbar AP or lateral radiographs, with the exception of Nordic countries combined data. Weight, procedure time and age were independently positively associated with total dose, and height (after adjusting for weight) was negatively associated, thus as height increased, the DAP decreased. PMID:26512196

  19. Patient-specific Monte Carlo dose calculations for 103Pd breast brachytherapy

    NASA Astrophysics Data System (ADS)

    Miksys, N.; Cygler, J. E.; Caudrelier, J. M.; Thomson, R. M.

    2016-04-01

    This work retrospectively investigates patient-specific Monte Carlo (MC) dose calculations for 103Pd permanent implant breast brachytherapy, exploring various necessary assumptions for deriving virtual patient models: post-implant CT image metallic artifact reduction (MAR), tissue assignment schemes (TAS), and elemental tissue compositions. Three MAR methods (thresholding, 3D median filter, virtual sinogram) are applied to CT images; resulting images are compared to each other and to uncorrected images. Virtual patient models are then derived by application of different TAS ranging from TG-186 basic recommendations (mixed adipose and gland tissue at uniform literature-derived density) to detailed schemes (segmented adipose and gland with CT-derived densities). For detailed schemes, alternate mass density segmentation thresholds between adipose and gland are considered. Several literature-derived elemental compositions for adipose, gland and skin are compared. MC models derived from uncorrected CT images can yield large errors in dose calculations especially when used with detailed TAS. Differences in MAR method result in large differences in local doses when variations in CT number cause differences in tissue assignment. Between different MAR models (same TAS), PTV {{D}90} and skin {{D}1~\\text{c{{\\text{m}}3}}} each vary by up to 6%. Basic TAS (mixed adipose/gland tissue) generally yield higher dose metrics than detailed segmented schemes: PTV {{D}90} and skin {{D}1~\\text{c{{\\text{m}}3}}} are higher by up to 13% and 9% respectively. Employing alternate adipose, gland and skin elemental compositions can cause variations in PTV {{D}90} of up to 11% and skin {{D}1~\\text{c{{\\text{m}}3}}} of up to 30%. Overall, AAPM TG-43 overestimates dose to the PTV ({{D}90} on average 10% and up to 27%) and underestimates dose to the skin ({{D}1~\\text{c{{\\text{m}}3}}} on average 29% and up to 48%) compared to the various MC models derived using the post-MAR CT images studied

  20. Patient-specific Monte Carlo dose calculations for (103)Pd breast brachytherapy.

    PubMed

    Miksys, N; Cygler, J E; Caudrelier, J M; Thomson, R M

    2016-04-07

    This work retrospectively investigates patient-specific Monte Carlo (MC) dose calculations for (103)Pd permanent implant breast brachytherapy, exploring various necessary assumptions for deriving virtual patient models: post-implant CT image metallic artifact reduction (MAR), tissue assignment schemes (TAS), and elemental tissue compositions. Three MAR methods (thresholding, 3D median filter, virtual sinogram) are applied to CT images; resulting images are compared to each other and to uncorrected images. Virtual patient models are then derived by application of different TAS ranging from TG-186 basic recommendations (mixed adipose and gland tissue at uniform literature-derived density) to detailed schemes (segmented adipose and gland with CT-derived densities). For detailed schemes, alternate mass density segmentation thresholds between adipose and gland are considered. Several literature-derived elemental compositions for adipose, gland and skin are compared. MC models derived from uncorrected CT images can yield large errors in dose calculations especially when used with detailed TAS. Differences in MAR method result in large differences in local doses when variations in CT number cause differences in tissue assignment. Between different MAR models (same TAS), PTV [Formula: see text] and skin [Formula: see text] each vary by up to 6%. Basic TAS (mixed adipose/gland tissue) generally yield higher dose metrics than detailed segmented schemes: PTV [Formula: see text] and skin [Formula: see text] are higher by up to 13% and 9% respectively. Employing alternate adipose, gland and skin elemental compositions can cause variations in PTV [Formula: see text] of up to 11% and skin [Formula: see text] of up to 30%. Overall, AAPM TG-43 overestimates dose to the PTV ([Formula: see text] on average 10% and up to 27%) and underestimates dose to the skin ([Formula: see text] on average 29% and up to 48%) compared to the various MC models derived using the post-MAR CT images

  1. Effect of low dose nicotinic acid on hyperphosphatemia in patients with end stage renal disease.

    PubMed

    Zahed, N S; Zamanifar, N; Nikbakht, H

    2016-01-01

    Hyperphosphatemia is a risk factor for ectopic calcification and coronary artery diseases in end stage renal diseases (ESRD). The aim of this study was to assess the effect of low-dose nicotinic acid on hyperphosphatemia in patients with ESRD. This randomized, double-blind clinical trial was done on 70 ESRD patients with serum phosphoure ≥5.5 mg/dl. Patients were randomly divided into two equal groups (n = 35) and the intervention group received niacin 25 mg/day as the initial dose. After 4 weeks, in patients who did not respond to treatment, niacin dose was increased up to 50 mg/dl. At the end of week 8, in case there was no treatment effect, the dose was raised to 100 mg/day. The appropriate response to treatment was defined as serum phosphorous level reductions <5.5 mg/dl. The age was 50.5 ± 14.3 years and duration of dialysis 5.1 ± 5.3 months. In the niacin group, mean phosphorus level decreased from 6.7 ± 0.84 mg/dl at the end of the 1(st) month to 5.8 ± 1.0 mg/dl at the end of the 2(nd) month and to 4.4 ± 1.4 mg/dl at the end of the 3(rd) month (P = 0.004). In the placebo group, mean phosphorus level increased from 6.5 ± 1.2 mg/dl to 7.2 ± 0.91 mg/dl at the end of the 3(rd) month (P = 0.006). In the niacin group, high density lipoprotein (HDL) increased significantly from 45.00 ± 14.9 to 47.2 ± 11.6 (P = 0.009). We conclude that niacin (100 mg/day) decreased phosphorus serum level and increased HDL serum level in patients on dialysis.

  2. [Digitalization without saturation dose using methyldigoxin. Experiences with 29 patients].

    PubMed

    Salvadè, G; Tartini, R; Moccetti, T

    1982-12-11

    The indications and performance of oral digitalization without saturation dose are evaluated on the basis of clinical parameters and plasma digitalis levels. A group of patients with evident cardiac insufficiency received a daily maintenance dosage of digitalis (2 tablets of 0.1 mg methyldigoxin) from the outset. After 7, 15 and 30 days the plasma concentration of methyldigoxin was measured. Objective and subjective signs of cardiac insufficiency were noted. In 28 of 29 patients the therapeutic plasma level (0.8-2.0 ng/ml) was achieved with a mean plasma digitalis concentration of 1.47 +/- 0.4 ng/ml. A clinical improvement was observed in 18 patients. On the 15th and 30th day of treatment the mean plasma level of methyldigoxin showed no significant difference: X15 = 1.51 +/- 0.57 ng/ml and X30 = 1.40 +/- 0.46 ng/ml. The measured plasma values were not influenced by the patient's weight or age. In 6 patients with renal insufficiency a clear correlation between the plasma level of methyldigoxin and the creatinine level was observed. The evaluation of ECG signs showed only minimal alterations of conduction and repolarisation. On the basis of these results conclusions are drawn with regard to the clinical value and use of this therapy.

  3. Low-dose preview for patient-specific, task-specific technique selection in cone-beam CT

    SciTech Connect

    Wang, Adam S.; Stayman, J. Webster; Otake, Yoshito; Siewerdsen, Jeffrey H.; Vogt, Sebastian; Kleinszig, Gerhard; Khanna, A. Jay; Gallia, Gary L.

    2014-07-15

    Purpose : A method is presented for generating simulated low-dose cone-beam CT (CBCT) preview images from which patient- and task-specific minimum-dose protocols can be confidently selected prospectively in clinical scenarios involving repeat scans. Methods : In clinical scenarios involving a series of CBCT images, the low-dose preview (LDP) method operates upon the first scan to create a projection dataset that accurately simulates the effects of dose reduction in subsequent scans by injecting noise of proper magnitude and correlation, including both quantum and electronic readout noise as important components of image noise in flat-panel detector CBCT. Experiments were conducted to validate the LDP method in both a head phantom and a cadaveric torso by performing CBCT acquisitions spanning a wide dose range (head: 0.8–13.2 mGy, body: 0.8–12.4 mGy) with a prototype mobile C-arm system. After injecting correlated noise to simulate dose reduction, the projections were reconstructed using both conventional filtered backprojection (FBP) and an iterative, model-based image reconstruction method (MBIR). The LDP images were then compared to real CBCT images in terms of noise magnitude, noise-power spectrum (NPS), spatial resolution, contrast, and artifacts. Results : For both FBP and MBIR, the LDP images exhibited accurate levels of spatial resolution and contrast that were unaffected by the correlated noise injection, as expected. Furthermore, the LDP image noise magnitude and NPS were in strong agreement with real CBCT images acquired at the corresponding, reduced dose level across the entire dose range considered. The noise magnitude agreed within 7% for both the head phantom and cadaveric torso, and the NPS showed a similar level of agreement up to the Nyquist frequency. Therefore, the LDP images were highly representative of real image quality across a broad range of dose and reconstruction methods. On the other hand, naïve injection ofuncorrelated noise

  4. A multiscale filter for noise reduction of low-dose cone beam projections

    NASA Astrophysics Data System (ADS)

    Yao, Weiguang; Farr, Jonathan B.

    2015-08-01

    The Poisson or compound Poisson process governs the randomness of photon fluence in cone beam computed tomography (CBCT) imaging systems. The probability density function depends on the mean (noiseless) of the fluence at a certain detector. This dependence indicates the natural requirement of multiscale filters to smooth noise while preserving structures of the imaged object on the low-dose cone beam projection. In this work, we used a Gaussian filter, \\text{exp}≤ft(-{{x}2}/2σ f2\\right) as the multiscale filter to de-noise the low-dose cone beam projections. We analytically obtained the expression of {σf} , which represents the scale of the filter, by minimizing local noise-to-signal ratio. We analytically derived the variance of residual noise from the Poisson or compound Poisson processes after Gaussian filtering. From the derived analytical form of the variance of residual noise, optimal σ f2 is proved to be proportional to the noiseless fluence and modulated by local structure strength expressed as the linear fitting error of the structure. A strategy was used to obtain the reliable linear fitting error: smoothing the projection along the longitudinal direction to calculate the linear fitting error along the lateral direction and vice versa. The performance of our multiscale filter was examined on low-dose cone beam projections of a Catphan phantom and a head-and-neck patient. After performing the filter on the Catphan phantom projections scanned with pulse time 4 ms, the number of visible line pairs was similar to that scanned with 16 ms, and the contrast-to-noise ratio of the inserts was higher than that scanned with 16 ms about 64% in average. For the simulated head-and-neck patient projections with pulse time 4 ms, the visibility of soft tissue structures in the patient was comparable to that scanned with 20 ms. The image processing took less than 0.5 s per projection with 1024   ×   768 pixels.

  5. A multiscale filter for noise reduction of low-dose cone beam projections.

    PubMed

    Yao, Weiguang; Farr, Jonathan B

    2015-08-21

    The Poisson or compound Poisson process governs the randomness of photon fluence in cone beam computed tomography (CBCT) imaging systems. The probability density function depends on the mean (noiseless) of the fluence at a certain detector. This dependence indicates the natural requirement of multiscale filters to smooth noise while preserving structures of the imaged object on the low-dose cone beam projection. In this work, we used a Gaussian filter, exp(-x2/2σ(2)(f)) as the multiscale filter to de-noise the low-dose cone beam projections. We analytically obtained the expression of σ(f), which represents the scale of the filter, by minimizing local noise-to-signal ratio. We analytically derived the variance of residual noise from the Poisson or compound Poisson processes after Gaussian filtering. From the derived analytical form of the variance of residual noise, optimal σ(2)(f)) is proved to be proportional to the noiseless fluence and modulated by local structure strength expressed as the linear fitting error of the structure. A strategy was used to obtain the reliable linear fitting error: smoothing the projection along the longitudinal direction to calculate the linear fitting error along the lateral direction and vice versa. The performance of our multiscale filter was examined on low-dose cone beam projections of a Catphan phantom and a head-and-neck patient. After performing the filter on the Catphan phantom projections scanned with pulse time 4 ms, the number of visible line pairs was similar to that scanned with 16 ms, and the contrast-to-noise ratio of the inserts was higher than that scanned with 16 ms about 64% in average. For the simulated head-and-neck patient projections with pulse time 4 ms, the visibility of soft tissue structures in the patient was comparable to that scanned with 20 ms. The image processing took less than 0.5 s per projection with 1024   ×   768 pixels.

  6. Dose-hair concentration relationship and pigmentation effects in patients on low-dose clozapine.

    PubMed

    Kronstrand, R; Roman, M; Hedman, M; Ahlner, J; Dizdar, N

    2007-06-01

    Several hair components have been suggested as possible molecular sites for drug binding and interaction. Of these, keratin and melanin have been investigated in some detail in order to assess the mechanisms by which the binding occurs. Substances that are positively charged at physiological pH may interact by electrostatic forces between their cationic groups and the anionic carboxylic groups on the surface of the melanin polymer. Studies in human subjects with grey hair have shown that various drugs are detectable in both the coloured (melanin rich) and white (melanin free) hair shafts of these individuals. Again this supports the proposition that keratin and hair proteins play an important role in the binding of drugs in hair. However, drugs are often found in significantly higher concentrations in pigmented hair strands than in senile white hair strands. Another interesting question is if the concentration measured in hair reflects the dose taken. Previous reports have both verified and rejected this hypothesis, but most agree that many factors have impact on the incorporation rate, melanin being one. In this study we obtained blood and hair samples from 12 grey haired patients treated with low-dose clozapine as an adjunct medication in their treatment against Parkinson disease. Each patient's hair was divided into a pigmented and a non-pigmented portion and those were analyzed separately. Clozapine and desmethylclozapine were analyzed with LC-MS-MS after extraction of the analytes from hair and plasma. Paired results from the analysis of pigmented and white hair confirmed the preference for binding to pigmented hair for both clozapine and its metabolite. A majority of the incorporated clozapine was found in the pigmented hair but, as drugs could be detected in white hair, binding to hair protein or association with other hair matrix account for a significant part of drug accumulation in hair. High correlations between dose and the measured concentration of

  7. Massive reduction of tumour load and normalisation of hyperprolactinaemia after high dose cabergoline in metastasised prolactinoma causing thoracic syringomyelia

    PubMed Central

    van Uum, S H M; van Alfen, N; Wesseling, P; van Lindert, E; Pieters, G; Nooijen, P; Hermus, A

    2004-01-01

    On administration of high dose cabergoline, 0.5 mg twice a day orally, the plasma prolactin levels decreased within one month and then normalised within 26 months. Tumour load reduced considerably but unfortunately, her signs and symptoms did not improve. This case illustrates that a high dose dopamine agonist might be an important therapeutic option in patients with a metastasised prolactinoma. PMID:15377706

  8. A Phase I Dose Escalation Study of the Triple Angiokinase Inhibitor Nintedanib Combined with Low-Dose Cytarabine in Elderly Patients with Acute Myeloid Leukemia

    PubMed Central

    Schliemann, Christoph; Gerss, Joachim; Wiebe, Stefanie; Mikesch, Jan-Henrik; Knoblauch, Nicola; Sauer, Tim; Angenendt, Linus; Kewitz, Tobias; Urban, Marc; Butterfass-Bahloul, Trude; Edemir, Sabine; Vehring, Kerstin; Müller-Tidow, Carsten

    2016-01-01

    Nintedanib (BIBF 1120), a potent multikinase inhibitor of VEGFR-1/-2/-3, FGFR-1/-2/-3 and PDGFR-α/-β, exerts growth inhibitory and pro-apoptotic effects in myeloid leukemic cells, especially when used in combination with cytarabine. This phase I study evaluated nintedanib in combination with low-dose cytarabine (LDAC) in elderly patients with untreated or relapsed/refractory acute myeloid leukemia (AML) ineligible for intensive chemotherapy in a 3+3 design. Nintedanib (dose levels 100, 150, and 200 mg orally twice daily) and LDAC (20 mg subcutaneous injection twice daily for 10 days) were administered in 28-day cycles. Dose-limiting toxicity (DLT) was defined as non-hematological severe adverse reaction CTC grade ≥ 4 with possible or definite relationship to nintedanib. Between April 2012 and October 2013, 13 patients (median age 73 [range: 62–86] years) were enrolled. One patient did not receive study medication and was replaced. Nine (69%) patients had relapsed or refractory disease and 6 (46%) patients had unfavorable cytogenetics. The most frequently reported treatment-related adverse events (AE) were gastrointestinal events. Twelve SAEs irrespective of relatedness were reported. Two SUSARs were observed, one fatal hypercalcemia and one fatal gastrointestinal infection. Two patients (17%) with relapsed AML achieved a complete remission (one CR, one CRi) and bone marrow blast reductions without fulfilling PR criteria were observed in 3 patients (25%). One-year overall survival was 33%. Nintedanib combined with LDAC shows an adequate safety profile and survival data are promising in a difficult-to-treat patient population. Continuation of this trial with a phase II recommended dose of 2 x 200 mg nintedanib in a randomized, placebo-controlled phase II study is planned. The trial is registered to EudraCT as 2011-001086-41. Trial Registration: ClinicalTrials.gov NCT01488344 PMID:27716819

  9. Dose reduction using prior image constrained compressed sensing (DR-PICCS)

    NASA Astrophysics Data System (ADS)

    Tang, Jie; Thériault Lauzier, Pascal; Chen, Guang-Hong

    2011-03-01

    A technique for dose reduction using prior image constrained compressed sensing (DR-PICCS) in computed tomography (CT) is proposed in this work. In DR-PICCS, a standard FBP reconstructed image is forward projected to get a fully sampled projection data set. Meanwhile, it is low-pass filtered and used as the prior image in the PICCS reconstruction framework. Next, the prior image and the forward projection data are used together by the PICCS algorithm to obtain a low noise DR-PICCS reconstruction, which maintains the spatial resolution of the original FBP images. The spatial resolution of DR-PICCS was studied using a Catphan phantom by MTF measurement. The noise reduction factor, CT number change and noise texture were studied using human subject data consisting of 20 CT colonography exams performed under an IRB-approved protocol. In each human subject study, six ROIs (two soft tissue, two colonic air columns, and two subcutaneous fat) were selected for the CT number and noise measurements study. Skewness and kurtosis were used as figures of merit to indicate the noise texture. A Bland-Altman analysis was performed to study the accuracy of the CT number. The results showed that, compared with FBP reconstructions, the MTF curve shows very little change in DR-PICCS reconstructions, spatial resolution loss is less than 0.1 lp/cm, and the noise standard deviation can be reduced by a factor of 3 with DR-PICCS. The CT numbers in FBP and DR-PICCS reconstructions agree well, which indicates that DR-PICCS does not change CT numbers. The noise textures indicators measured from DR-PICCS images are in a similar range as FBP images.

  10. Sex differences in nicotine self-administration in rats during progressive unit dose reduction: Implications for nicotine regulation policy

    PubMed Central

    Grebenstein, Patricia; Burroughs, Danielle; Zhang, Yan; LeSage, Mark G.

    2013-01-01

    Reducing the nicotine content in tobacco products is being considered by the FDA as a policy to reduce the addictiveness of tobacco products. Understanding individual differences in response to nicotine reduction will be critical to developing safe and effective policy. Animal and human research demonstrating sex differences in the reinforcing effects of nicotine suggests that males and females may respond differently to nicotine-reduction policies. However, no studies have directly examined sex differences in the effects of nicotine unit-dose reduction on nicotine self-administration (NSA) in animals. The purpose of the present study was to examine this issue in a rodent self-administration model. Male and female rats were trained to self-administer nicotine (0.06 mg/kg) under an FR 3 schedule during daily 23 h sessions. Rats were then exposed to saline extinction and reacquisition of NSA, followed by weekly reductions in the unit dose (0.03 to 0.00025 mg/kg) until extinction levels of responding were achieved. Males and females were compared with respect to baseline levels of intake, resistance to extinction, degree of compensatory increases in responding during dose reduction, and the threshold reinforcing unit dose of nicotine. Exponential demand-curve analysis was also conducted to compare the sensitivity of males and females to increases in the unit price (FR/unit dose) of nicotine (i.e., elasticity of demand or reinforcing efficacy). Females exhibited significantly higher baseline intake and less compensation than males. However, there were no sex differences in the reinforcement threshold or elasticity of demand. Dose–response relationships were very well described by the exponential demand function (r2 values > 0.96 for individual subjects). These findings suggest that females may exhibit less compensatory smoking in response to nicotine reduction policies, even though their nicotine reinforcement threshold and elasticity of demand may not differ from

  11. The study of external dose rate and retained body activity of patients receiving 131I therapy for differentiated thyroid carcinoma.

    PubMed

    Zhang, Haiying; Jiao, Ling; Cui, Songye; Wang, Liang; Tan, Jian; Zhang, Guizhi; He, Yajing; Ruan, Shuzhou; Fan, Saijun; Zhang, Wenyi

    2014-10-21

    Radiation safety is an integral part of targeted radionuclide therapy. The aim of this work was to study the external dose rate and retained body activity as functions of time in differentiated thyroid carcinoma patients receiving 131I therapy. Seventy patients were stratified into two groups: the ablation group (A) and the follow-up group (FU). The patients' external dose rate was measured, and simultaneously, their retained body radiation activity was monitored at various time points. The equations of the external dose rate and the retained body activity, described as a function of hours post administration, were fitted. Additionally, the release time for patients was calculated. The reduction in activity in the group receiving a second or subsequent treatment was more rapid than the group receiving only the initial treatment. Most important, an expeditious method was established to indirectly evaluate the retained body activity of patients by measuring the external dose rate with a portable radiation survey meter. By this method, the calculated external dose rate limits are 19.2, 8.85, 5.08 and 2.32 μSv·h-1 at 1, 1.5, 2 and 3 m, respectively, according to a patient's released threshold level of retained body activity <400 MBq. This study is beneficial for radiation safety decision-making.

  12. Patient doses and image quality in digital chest radiology.

    PubMed

    Salát, D; Nikodemová, D

    2008-01-01

    Chest X-ray examination is one of the most frequently required procedures used in clinical practice. For studying the image quality of different X-ray digital systems and for the control of patient doses during chest radiological examinations, the standard anthropomorphic lung/chest phantom RSD 330 has been used and exposed in different digital modalities available in Slovakia. To compare different techniques of chest examination, a special software has been developed that enables researchers to compare digital imaging and communications in medicine header images from different digital modalities, using a special viewer. In this paper, this special software has been used for an anonymous correspondent audit for testing image quality evaluation by comparing various parameters of chest imaging, evaluated by 84 Slovak radiologists. The results of the comparison have shown that the majority of the participating radiologists felt that the highest image quality is reached with a flat panel, assessed by the entrance surface dose value, which is approximately 75% lower than the diagnostic reference level of chest examination given in the Slovak legislation. Besides the results of the audit, the possibilities of using the software for optimisation, education and training of medical students, radiological assistants, physicists and radiologists in the field of digital radiology will be described.

  13. [State of the art and future trends in technology for computed tomography dose reduction].

    PubMed

    Calzado Cantera, A; Hernández-Girón, I; Salvadó Artells, M; Rodríguez González, R

    2013-12-01

    The introduction of helical and multislice acquisitions in CT scanners together with decreased image reconstruction times has had a tremendous impact on radiological practice. Technological developments in the last 10 to 12 years have enabled very high quality images to be obtained in a very short time. Improved image quality has led to an increase in the number of indications for CT. In parallel to this development, radiation exposure in patients has increased considerably. Concern about the potential health risks posed by CT imaging, reflected in diverse initiatives and actions by official organs and scientific societies, has prompted the search for ways to reduce radiation exposure in patients without compromising diagnostic efficacy. To this end, good practice guidelines have been established, special applications have been developed for scanners, and research has been undertaken to optimize the clinical use of CT. Noteworthy technical developments incorporated in scanners include the different modes of X-ray tube current modulation, automatic selection of voltage settings, selective organ protection, adaptive collimation, and iterative reconstruction. The appropriate use of these tools to reduce radiation doses requires thorough knowledge of how they work.

  14. Shielding for neutron scattered dose to the fetus in patients treated with 18 MV x-ray beams.

    PubMed

    Roy, S C; Sandison, G A

    2000-08-01

    Neutrons are associated with therapeutic high energy x-ray beams as a contaminant that contributes significant unwanted dose to the patient. Measurement of both photon and neutron scattered dose at the position of a fetus from chest irradiation by a large field 18 MV x-ray beam was performed using an ionization chamber and superheated drop detector, respectively. Shielding construction to reduce this scattered dose was investigated using both lead sheet and borated polyethylene slabs. A 7.35 cm lead shield reduced the scattered photon dose by 50% and the scattered neutron dose by 40%. Adding 10 cm of 5% borated polyethylene to this lead shield reduced the scattered neutron dose by a factor of 7.5 from the unshielded value. When the 5% borated polyethylene was replaced by the same thickness of 30% borated polyethylene there was no significant change in the reduction of neutron scatter dose. The most efficient shield studied reduced the neutron scatter dose by a factor of 10. The results indicate that most of the scattered neutrons present at the position of the fetus produced by an 18 MV x-ray beam are of low energy and in the thermal to 0.57 MeV range since lead is almost transparent to neutrons with energies lower than 0.57 MeV. This article constitutes the first report of an effective shield to reduce neutron dose at the fetus when treating a pregnant woman with a high energy x-ray beam.

  15. Effects of shielding the radiosensitive superficial organs of ORNL pediatric phantoms on dose reduction in computed tomography

    PubMed Central

    Akhlaghi, Parisa; Miri-Hakimabad, Hashem; Rafat-Motavalli, Laleh

    2014-01-01

    In computed tomography (CT), some superficial organs which have increased sensitivity to radiation, receive doses that are significant enough to be matter of concern. Therefore, in this study, the effects of using shields on the amount of dose reduction and image quality was investigated for pediatric imaging. Absorbed doses of breasts, eyes, thyroid and testes of a series of pediatric phantoms without and with different thickness of bismuth and lead were calculated by Monte Carlo simulation. Appropriate thicknesses of shields were chosen based on their weights, X-ray spectrum, and the amount of dose reduction. In addition, the effect of lead shield on image quality of a simple phantom was assessed quantitatively using region of interest (ROI) measurements. Considering the maximum reduction in absorbed doses and X-ray spectrum, using a lead shield with a maximum thickness of 0.4 mm would be appropriate for testes and thyroid and two other organs (which are exposed directly) should be protected with thinner shields. Moreover, the image quality assessment showed that lead was associated with significant increases in both noise and CT attenuation values, especially in the anterior of the phantom. Overall, the results suggested that shielding is a useful optimization tool in CT. PMID:25525312

  16. Dosing and Safety Implications for Oncologists When Administering Everolimus to Patients With Hormone Receptor-Positive Breast Cancer.

    PubMed

    Rugo, Hope S

    2016-02-01

    Aberrations in the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin pathway are common abnormalities in breast cancer and are associated with the development of resistance to endocrine- and human epidermal growth factor receptor (HER)2-targeted therapies. Because of the significant improvement in progression-free survival for everolimus plus exemestane compared with exemestane plus placebo, everolimus, an mTOR inhibitor, was approved in the United States for the treatment of patients with hormone receptor-positive (HR+), HER-negative, advanced breast cancer whose disease had progressed while receiving letrozole or anastrozole. To provide optimal prevention and management strategies, it is crucial that clinicians are aware of the adverse events (AEs) associated with mTOR inhibition. Understanding the appropriate dose modifications will help reduce toxicity and improve drug tolerance, thus achieving the optimal benefit from everolimus. Analyses of data from the Breast Cancer Trials of Oral Everolimus 2 trial have shown that, despite a greater frequency of AEs in the everolimus plus exemestane treatment arm, the AEs were effectively managed with temporary dose reductions or interruptions. In some cases, the full dose of everolimus could be resumed. Despite a lower mean dose and duration of exposure in patients aged ≥ 70 versus < 70 years, everolimus plus exemestane was similarly efficacious, suggesting that appropriate dose reductions for toxicity will not adversely impact efficacy. Appropriate modification of the everolimus dose and dose delay according to the severity of AEs, with resumption of the optimal dose of everolimus when toxicity has improved, will positively affect patient outcomes in HR+ advanced breast cancer.

  17. Effective doses to family members of patients treated with radioiodine-131

    NASA Astrophysics Data System (ADS)

    Zdraveska Kocovska, M.; Vaskova, O.; Majstorov, V.; Kuzmanovska, S.; Pop Gjorceva, D.; Spasic Jokic, V.

    2011-09-01

    The purpose of this study was to evaluate the effective dose to family members of thyroid cancer and hyperthyroid patients treated with radioiodine-131, and also to compare the results with dose constraints proposed by the International Commission of Radiological Protection (ICRP) and the Basic Safety Standards (BSS) of the International Atomic Energy Agency (IAEA). For the estimation of the effective doses, sixty family members of sixty patients, treated with radioiodine-131, and thermoluminiscent dosimeters (Model TLD 100) were used. Thyroid cancer patients were hospitalized for three days, while hyperthyroid patients were treated on out-patient basis. The family members wore TLD in front of the torso for seven days. The radiation doses to family members of thyroid cancer patients were well below the recommended dose constraint of 1 mSv. The mean value of effective dose was 0.21 mSv (min 0.02 - max 0.51 mSv). Effective doses, higher than 1 mSv, were detected for 11 family members of hyperthyroid patients. The mean value of effective dose of family members of hyperthyroid patients was 0.87 mSv (min 0.12 - max 6.79). The estimated effective doses to family members of hyperthyroid patients were higher than the effective doses to family members of thyroid carcinoma patients. These findings may be considered when establishing new national guidelines concerning radiation protection and release of patients after a treatment with radioiodine therapy.

  18. A Monte Carlo study on quantifying the amount of dose reduction by shielding the superficial organs of an Iranian 11-year-old boy

    PubMed Central

    Akhlaghi, Parisa; Hoseinian-Azghadi, Elie; Miri-Hakimabad, Hashem; Rafat-Motavalli, Laleh

    2016-01-01

    A method for minimizing organ dose during computed tomography examinations is the use of shielding to protect superficial organs. There are some scientific reports that usage of shielding technique reduces the surface dose to patients with no appreciable loss in diagnostic quality. Therefore, in this Monte Carlo study based on the phantom of a 11-year-old Iranian boy, the effect of using an optimized shield on dose reduction to body organs was quantified. Based on the impact of shield on image quality, lead shields with thicknesses of 0.2 and 0.4 mm were considered for organs exposed directly and indirectly in the scan range, respectively. The results showed that there is 50%–62% reduction in amounts of dose for organs located fully or partly in the scan range at different tube voltages and modeling the true location of all organs in human anatomy, especially the ones located at the border of the scan, range affects the results up to 49%. PMID:28144117

  19. Predictors of smoking reduction outcomes in a sample of 287 patients with schizophrenia spectrum disorders.

    PubMed

    Wu, Bo-Jian; Lan, Tsuo-Hung

    2017-02-01

    Many studies have investigated whether a type of antipsychotics or type of adjuvant is associated with smoking reduction in patients with schizophrenia. However, there has been no study exploring a comprehensive range of factors related to smoking reduction in schizophrenia patients. We analyzed a dataset of 287 smoking patients with schizophrenia who participated in an 8-week open-label study with high- (n = 90) or low-dose nicotine dermal patches (n = 132) or bupropion (n = 65). A logistic regression model and a linear mixed model were used to explore factors associated with the outcomes of smoking cessation and reduction, i.e., the number of cigarettes smoked and the level of nicotine dependence. The total cessation rate was 6.3 % (18/287). There were no significant predictors of cessation. The time effect of reduction was significant during the program (p = 0.001). Type of antipsychotics (p = 0.018), readiness to quit (p = 0.014), baseline number of cigarettes smoked per day (p = 0.001), and nicotine dependence level (p = 0.001) were significantly associated with smoking reduction. Patients on first-generation antipsychotics (n = 129) or clozapine (n = 70) reduced their smoking more than those on non-clozapine second-generation antipsychotics (n = 74). Patients in the preparation stage (n = 97) or in the contemplation (n = 70) reduced their smoking more than those in the precontemplation stage (n = 120). The mechanisms of tobacco addiction need to be better understood for further development of effective cessation programs in patients with schizophrenia.

  20. Exposure reductions encouraged by the determination of the effective dose equivalent for non-uniform exposures

    SciTech Connect

    Matheny, M.D.; Brown, C.G.; Dyer, S.G.

    1994-08-01

    DOE Order 5480.11 requires calculation of the effective dose equivalent (EDE) due to non-uniform radiation fields using ICRP-26 weighting factors. To comply with this requirement, Westinghouse Savannah River Company (WSRC) developed a simple dose calculation scheme based on a draft report by the External Dosimetry Working Group of the Health Physics Society Standards Committee. The calculations involved are fairly simple and provide a conservative dose estimate. The resulting EDE estimate provides a much better representation of the risk to the monitored individual than the more prevalent practice of assigning the highest measured dose. Details of the dose assessment methodology are included as an attachment.

  1. Skin and gonadal dose reduction during hip radiography of the bull.

    PubMed

    Wood, A K; Blockey, B; Reynolds, K M; Leith, I S; Burns, P A

    1979-10-01

    Radiology is being used to an increasing extent in the clinical diagnosis of hip lameness in bulls. Consequent gonadal doses may have important implications in later breeding programmes. Skin and gonadal doses were recorded during hip radiography of 18 bulls. An additional 0.13 mm copper filtration reduced skin dose by more than one third, but had no effect on gonadal dose. The average radiation dose to the gonads was approximately halved by completely surrounding the scrotum with lead sheeting 0.95 mm in thickness.

  2. Butaclamol in newly admitted chronic schizophrenic patients: a modified fixed-dose dose-range design.

    PubMed

    Clark, M L; Costiloe, J P; Wood, F; Paredes, A; Fulkerson, F G

    1977-11-01

    In a double-blind placebo controlled study of newly admitted chronic schizophrenics, an attempt was made to further evaluate the safety, acceptability, and effectiveness of BT in doses of 10, 20, and 40 mg. Significant dose related responses occurred on several behavioral variables by the first week of treatment. Maximum clinical response appeared to be at the 20-40 mg. dose level. Extrapyramidal signs occurred at all doses, but with greater severity at higher doses. Excessive daytime drowsiness occurred in all groups but with longer duration and greater intensity in the 20 mg. group. Rebound insomnia occurred after the abrupt withdrawal of BT at all dose levels suggesting the desirability of further study of its hypnotic properties.

  3. Patient radiation doses in uterine artery embolisation using Monte Carlo simulation.

    PubMed

    Miñano, J A; Canis, M; Roldán, J M; Sarsa, A

    2014-01-01

    This study aims at quantification of ovarian dose in uterine artery embolisation to study the level of optimisation of this dose. Individual anatomical data and all relevant exposure parameters of individual beam projections were recorded in 52 patients who underwent uterine artery embolisation in two angiography units. The recorded information was used to calculate the individual ovarian doses by Monte Carlo simulation. The mean dose-area product was 196 Gy cm(2). The corresponding mean ovarian dose was 149 mGy. The performance of the two angiography units was analysed starting from these data. Dose-area product and ovarian doses obtained in this study were compared with data from other uterine artery embolisation patient dose studies. It was concluded that although the mean dose-area product and ovarian dose are acceptable, it is possible to optimise the procedure by improving the performance of the units.

  4. Approved drugs and their problems in patient care: routes of administration and dosing.

    PubMed

    Cook, Stuart D

    2007-08-15

    Problems in patient care with regard to route of administration and dosing of currently approved drugs are reviewed. Dose, frequency and route of administration can make a difference in efficacy, side effects, quality of life, antigenicity, cost, and compliance.

  5. Alternate-day dosing of linagliptin in type 2 diabetes patients controlled on once daily dose: A case series

    PubMed Central

    Baruah, Manash P.; Bhuyan, Sonali B.; Deka, Jumi; Bora, Jatin; Bora, Smritisikha; Barkakati, Murchana

    2016-01-01

    Linagliptin, a dipeptidyl peptidase 4 (DPP 4) inhibitor with a long terminal half life, significantly inhibits the DPP 4 enzyme at a steady state up to 48 h after the last dose. The present case series examined the hypothesis that linagliptin retains its efficacy during alternate day dosing in type 2 diabetes patients when switched over from once daily (OD) dosing. Eight type 2 diabetes patients maintaining stable glycosylated hemoglobin (HbA1c) with acceptable fasting plasma glucose and postprandial glucose levels and receiving linagliptin 5 mg OD for at least 6 weeks, with a stable dose of concomitant antidiabetic medications were given linagliptin 5 mg every alternate day. The median HbA1c while on the OD regimen was 6.1% (43 mmol/mol) (range: 5.8–6.9% [40–52 mmol/mol]) and median duration of diabetes was 7 years (range: 0.75–16 years). After a median follow-up period of 21weeks,the glycemic control was maintained in all patients similar to their baseline values (median HbA1c: 6.0% [42 mmol/mol], range: 5.1–7.1% [32–54 mmol/mol]). The body weight, fasting, and random glucose levels at baseline were also well maintained at the end of treatment. Optimal glycemic status maintained in our study population favors our hypothesis that linagliptin used alternate daily after switching from initial OD dose of the drug in patients on a stable background antidiabetic medications retains its efficacy. Paradoxically, alternate day dosing may affect compliance if the patient forgets when they took the last dose. Further studies including larger cohorts are needed to validate this finding and identify patients who can benefit from the alternate day regimen. PMID:27366728

  6. SYSTEM UPGRADE ON PHILIPS ALLURA FD20 ANGIOGRAPHY SYSTEMS: EFFECTS ON PATIENT SKIN DOSE AND STATIC IMAGE QUALITY.

    PubMed

    Ryckx, Nick; Sans-Merce, Marta; Meuli, Reto; Zerlauth, Jean-Baptiste; Verdun, Francis R

    2016-06-01

    Fluoroscopically guided procedures might be highly irradiating for patients, possibly leading to skin injuries. In such a context, every effort should be done to lower patient exposure as much as possible. Moreover, patient dose reduction does not only benefit to the patient but also allows reducing staff exposure. In this framework, Philips Healthcare recently introduced a system upgrade for their angiography units, called 'AlluraClarity'. The authors performed air kerma rate measurements for all available fluoroscopy modes and air kerma per frame measurements for the digital subtraction angiography protocols, along with subjective spatial resolution and low-contrast detectability assessments using a standard QA phantom. Air kerma reductions ranging from 25.5 to 84.4 % were found, with no significant change in image quality when switching from a standard operating mode to an upgraded version. These results are confirmed by the comparison of actual patient exposures for similar procedures.

  7. Antithrombin III Doses Rounded to Available Vial Sizes in Critically Ill Pediatric Patients

    PubMed Central

    Stockton, Winifred M.; Padilla-Tolentino, Eimeira

    2017-01-01

    OBJECTIVES Children have decreased levels of antithrombin III (AT III) compared to adults. These levels may be further decreased during acute illness. Administration of exogenous AT III can increase anticoagulant efficacy. The objective of this study was to evaluate AT III doses rounded to available vial sizes compared to partial vial doses in critically ill pediatric patients, including patients receiving extracorporeal membrane oxygenation (ECMO) and continuous renal replacement therapy (CRRT). METHOD This retrospective review evaluated pediatric patients 0–18 years of age admitted to a 24-bed medical/surgical pediatric intensive care unit between June 1, 2012, and December 31, 2014, who received plasma-derived AT III. Patients received unfractionated heparin, low-molecular-weight heparin, or no anticoagulation. This review included patients who received ECMO and CRRT. RESULTS Eighty doses of AT III were administered to 24 patients (38 full vial size doses and 42 partial vial size doses). The AT III level following dose administration was ≥80% for 26 full vial doses (70%) and 16 partial vial doses (41%; p = 0.010). For patients who received multiple doses of AT III, the median time between doses was 45 hours following full vial doses, and 23 hours following partial vial doses (p = 0.011). Seven patients (29%) had documentation of new or increased bleeding. The median waste prevented from rounding doses to full vial sizes was 363 units. CONCLUSIONS After receiving AT III doses rounded to full vial sizes, patients were more likely to have a therapeutic AT III level and a longer interval between administrations. Rounding AT III doses to full vial sizes reduces waste and can result in cost savings.

  8. Reduction of aspirin-induced fecal blood loss with low-dose misoprostol tablets in man

    SciTech Connect

    Cohen, M.M.; Clark, L.; Armstrong, L.; D'Souza, J.

    1985-07-01

    Misoprostol (SC-29333), a synthetic prostaglandin E1 methyl ester analog, was given simultaneously with acetylsalicylic acid in a double-blind, placebo-controlled randomized prospective study of 32 healthy human male subjects. Fecal blood loss was measured for eight days using the /sup 51/Cr-labeled red blood cell technique. Aspirin (650 mg qid) and misoprostol (25 micrograms qid) or placebo were given during days 3, 4, and 5. There was a significant (P less than 0.05) increase in median blood loss (modified Friedman test) from 0.81 to 6.05 ml/day in the aspirin with placebo group (N = 16). Median blood loss was increased (from 0.75 to 3.75 ml/day) in the aspirin with misoprostol group (N = 16), but this was significantly less (Mann-Whitney U test, P less than 0.01) than the placebo group. Mean serum salicylate concentrations in the placebo and misoprostol groups were similar (7.8 and 6.8 micrograms/ml, respectively). There were no significant changes in laboratory values in any of the subjects studied, nor were any major side-effects encountered. This study demonstrates that oral misoprostol reduces aspirin-induced gastrointestinal bleeding even when administered simultaneously and at a dose level below its threshold for significant acid inhibition. This indicates a potential role for misoprostol in the prevention of gastric mucosal damage in selected patients.

  9. Standard dosing of amikacin and gentamicin in critically ill patients results in variable and subtherapeutic concentrations.

    PubMed

    Roger, Claire; Nucci, Bastian; Molinari, Nicolas; Bastide, Sophie; Saissi, Gilbert; Pradel, Gael; Barbar, Saber; Aubert, Clément; Lloret, Sophie; Elotmani, Loubna; Polge, Anne; Lefrant, Jean-Yves; Roberts, Jason A; Muller, Laurent

    2015-07-01

    Low peak plasma concentrations (Cmax) of amikacin and gentamicin are reported in intensive care unit (ICU) patients after administration of the first dose. The present study aimed to describe the proportion of ICU patients in whom an adequate Cmax was achieved throughout the course of therapy. Septic ICU patients with an indication for intravenous amikacin or gentamicin were eligible for inclusion in this single-centre observational study. The first and subsequent doses and the corresponding Cmax values were recorded. The target Cmax was ≥60mg/L for amikacin and ≥30mg/L for gentamicin. Amikacin and gentamicin plasma concentrations were available in 66 and 24 patients, respectively (59±17 years; 79±19kg; height 169±12cm; SAPS II score 46±19). Pulmonary, abdominal and urinary tract infections were diagnosed in 64 patients. Culture-positive infection was confirmed in 65 patients (72%). A target first Cmax was achieved in 17/90 patients (19%). For amikacin, the target Cmax was achieved in 16/66 patients (24%) after the initial dose. In the 50 remaining patients, a change in dosing was performed in 14 patients, leading adequate peak plasma level in 2 patients. For gentamicin, the targeted Cmax was achieved in only 1/24 patient (4%) after the initial dose and was never achieved after the third dose. In conclusion, standard dosing of amikacin or gentamicin led to adequate Cmax in only 19% of patients. Subtherapeutic Cmax were not significantly corrected after subsequent doses.

  10. Radioimmunotherapy treatment planning based on radiation absorbed dose or patient size

    SciTech Connect

    Eary, J.F.; Krohn, K.A.; Press, O.W. |

    1996-05-01

    Several approaches have been used to plan treatment doses for patients undergoing radioimmunotherapy. Investigators often use fixed doses, or doses based on patient size (mCi/kg or mCi/m{sup 2}). Our treatment protocols for lymphoma and leukemia involved calculation of tissue radiation absorbed dose based on images from a trace labeled infusion of antibody prior to treatment. In a recent analysis of patients treated in the Phase I and II dose escalation trial for treatment of non-Hodgkin`s lymphoma with I-131 anti-CD20 antibody (B1), we investigated the relationship between our dosimetry based treatment and dose based on patient size. Tissue radiation dose for several normal organs and for tumors were plotted versus the mCi administered per kg or m{sup 2} of the patient to evaluate the relationship between the two treatment approaches. These graphs showed correlation coefficients ranging from 0.021 to 0.684, demonstrating the variability in antibody catabolism between patients. This means that fixed doses or administrations based on patient size do not deliver consistent radiation doses to normal organs or tumors. This finding was extrapolated to show that toxicity from doses based on patient size di not correlate with treatment dose; those based on calculated rad/organ did. Phase I clinical trials using treatment doses based on patient size where there are likely to be variations in patient antibody catabolism will result in confounding toxicities at apparently similar mCi dose levels. Use of pre-treatment scans for treatment dose planning are worth the additional effort by normalizing the normal tissue toxicity.

  11. Computational assessment of effective dose and patient specific doses for kilovoltage stereotactic radiosurgery of wet age-related macular degeneration

    NASA Astrophysics Data System (ADS)

    Hanlon, Justin Mitchell

    Age-related macular degeneration (AMD) is a leading cause of vision loss and a major health problem for people over the age of 50 in industrialized nations. The current standard of care, ranibizumab, is used to help slow and in some cases stabilize the process of AMD, but requires frequent invasive injections into the eye. Interest continues for stereotactic radiosurgery (SRS), an option that provides a non-invasive treatment for the wet form of AMD, through the development of the IRay(TM) (Oraya Therapeutics, Inc., Newark, CA). The goal of this modality is to destroy choroidal neovascularization beneath the pigment epithelium via delivery of three 100 kVp photon beams entering through the sclera and overlapping on the macula delivering up to 24 Gy of therapeutic dose over a span of approximately 5 minutes. The divergent x-ray beams targeting the fovea are robotically positioned and the eye is gently immobilized by a suction-enabled contact lens. Device development requires assessment of patient effective dose, reference patient mean absorbed doses to radiosensitive tissues, and patient specific doses to the lens and optic nerve. A series of head phantoms, including both reference and patient specific, was derived from CT data and employed in conjunction with the MCNPX 2.5.0 radiation transport code to simulate treatment and evaluate absorbed doses to potential tissues-at-risk. The reference phantoms were used to evaluate effective dose and mean absorbed doses to several radiosensitive tissues. The optic nerve was modeled with changeable positions based on individual patient variability seen in a review of head CT scans gathered. Patient specific phantoms were used to determine the effect of varying anatomy and gaze. The results showed that absorbed doses to the non-targeted tissues were below the threshold levels for serious complications; specifically the development of radiogenic cataracts and radiation induced optic neuropathy (RON). The effective dose

  12. Dose reduction efforts for pediatric head CT imaging in Washington State trauma centers: follow-up survey results

    PubMed Central

    Kanal, Kalpana M.; Rivara, Frederick P.; Jarvik, Jeffrey G.; Vavilala, Monica S.

    2014-01-01

    Purpose To examine variation in pediatric trauma head CT imaging protocols in Washington State trauma centers (TCs) in 2012 and compare to a previous survey conducted in 2008/09. Methods A mixed-mode (online and paper) survey was sent to all adult and pediatric Washington State TCs (levels 1–5). Respondents provided information about the CT scanner used for pediatric head scans and technical information about pediatric dose reduction protocols. Mean head effective dose and organ dose for a female baby were estimated. Results were compared to previous data. Results Sixty-one of 76 TCs responded to the 2012 survey (response rate 80.3%; response rate in 2008/09 survey was 76%). In 2012, 91.7% reported having a dedicated pediatric protocol (87.7% in 2008/09). Protective shielding use ranged from 80 to 100% across both survey years. In 2012, 2.5 times more TCs provided sufficient information to conduct dose calculations than in 2008/09. Estimated mean CTDIvol was 23.1 mGy in 2012, compared to 34.8 mGy in 2008/09 (p=0.01). Estimated mean DLP was also significantly lower in 2012 than 2009/08 (307.6 mGy*cm vs. 430.1 mGy*cm, respectively; p=0.04). Wide variation in mean effective dose was observed for level 3 and 4 TCs in 2012, similar to variation observed in 2008/09 among level 4 TCs. Mean organ dose was significantly lower in 2012 for eye lens and brain, but higher for thyroid than 2008/09 (p<0.05). Conclusions While most Washington State TCs employ dose reduction protocols for pediatric head CTs, and some measures were lower in 2012, variation in protocols use and estimated dose continues to exist. More complete responses in 2012 suggest improved understanding of the importance of pediatric dose reduction efforts. Education and institutional protocols are necessary to reduce pediatric radiation dose from head CTs. PMID:24360905

  13. Local-Reference Patient Dose Evaluation in Conventional Radiography Examinations in Mazandaran, Iran

    PubMed Central

    Khoshdel-Navi, D.; Shabestani-Monfared, A.; Deevband, M. R.; Abdi, R.; Nabahati, M.

    2016-01-01

    quality while reduction of patient dose. PMID:27672626

  14. Curtailing patient-specific IMRT QA procedures from 2D dose error distribution

    PubMed Central

    Kurosu, Keita; Sumida, Iori; Mizuno, Hirokazu; Otani, Yuki; Oda, Michio; Isohashi, Fumiaki; Seo, Yuji; Suzuki, Osamu; Ogawa, Kazuhiko

    2016-01-01

    A patient-specific quality assurance (QA) test is conducted to verify the accuracy of dose delivery. It generally consists of three verification processes: the absolute point dose difference, the planar dose differences at each gantry angle, and the planar dose differences by 3D composite irradiation. However, this imposes a substantial workload on medical physicists. The objective of this study was to determine whether our novel method that predicts the 3D delivered dose allows certain patient-specific IMRT QAs to be curtailed. The object was IMRT QA for the pelvic region with regard to point dose and composite planar dose differences. We compared measured doses, doses calculated in the treatment planning system, and doses predicted by in-house software. The 3D predicted dose was reconstructed from the per-field measurement by incorporating the relative dose error distribution into the original dose grid of each beam. All point dose differences between the measured and the calculated dose were within ±3%, whereas 93.3% of them between the predicted and the calculated dose were within ±3%. As for planar dose differences, the gamma passing rates between the calculated and the predicted dose were higher than those between the calculated and the measured dose. Comparison and statistical analysis revealed a correlation between the predicted and the measured dose with regard to both point dose and planar dose differences. We concluded that the prediction-based approach is an accurate substitute for the conventional measurement-based approach in IMRT QA for the pelvic region. Our novel approach will help medical physicists save time on IMRT QA. PMID:26661854

  15. Curtailing patient-specific IMRT QA procedures from 2D dose error distribution.

    PubMed

    Kurosu, Keita; Sumida, Iori; Mizuno, Hirokazu; Otani, Yuki; Oda, Michio; Isohashi, Fumiaki; Seo, Yuji; Suzuki, Osamu; Ogawa, Kazuhiko

    2016-06-01

    A patient-specific quality assurance (QA) test is conducted to verify the accuracy of dose delivery. It generally consists of three verification processes: the absolute point dose difference, the planar dose differences at each gantry angle, and the planar dose differences by 3D composite irradiation. However, this imposes a substantial workload on medical physicists. The objective of this study was to determine whether our novel method that predicts the 3D delivered dose allows certain patient-specific IMRT QAs to be curtailed. The object was IMRT QA for the pelvic region with regard to point dose and composite planar dose differences. We compared measured doses, doses calculated in the treatment planning system, and doses predicted by in-house software. The 3D predicted dose was reconstructed from the per-field measurement by incorporating the relative dose error distribution into the original dose grid of each beam. All point dose differences between the measured and the calculated dose were within ±3%, whereas 93.3% of them between the predicted and the calculated dose were within ±3%. As for planar dose differences, the gamma passing rates between the calculated and the predicted dose were higher than those between the calculated and the measured dose. Comparison and statistical analysis revealed a correlation between the predicted and the measured dose with regard to both point dose and planar dose differences. We concluded that the prediction-based approach is an accurate substitute for the conventional measurement-based approach in IMRT QA for the pelvic region. Our novel approach will help medical physicists save time on IMRT QA.

  16. Effectiveness of low-dose pasireotide in a patient with Cushing’s disease: antiproliferative effect and predictivity of a short pasireotide suppression test

    PubMed Central

    Grossrubatscher, Erika; Zampetti, Benedetta; Dalino Ciaramella, Paolo; Doneda, Paola; Loli, Paola

    2015-01-01

    Key Clinical Message This case shows efficacy of low-dose pasireotide in biochemical and clinical control of severe hypercortisolism and in tumor volume reduction in a patient with an ACTH-secreting macroadenoma. The drug may be an option for long-term treatment in some patients where control of tumor mass is an important clinical endpoint. PMID:26331021

  17. Effectiveness of low-dose pasireotide in a patient with Cushing's disease: antiproliferative effect and predictivity of a short pasireotide suppression test.

    PubMed

    Grossrubatscher, Erika; Zampetti, Benedetta; Dalino Ciaramella, Paolo; Doneda, Paola; Loli, Paola

    2015-08-01

    This case shows efficacy of low-dose pasireotide in biochemical and clinical control of severe hypercortisolism and in tumor volume reduction in a patient with an ACTH-secreting macroadenoma. The drug may be an option for long-term treatment in some patients where control of tumor mass is an important clinical endpoint.

  18. [The reduction of the dose to the lung in whole-body irradiation with cobalt-60 gamma rays (author's transl)].

    PubMed

    Hochhäuser, E; Balk, O A

    1980-09-01

    In order to reduce the exposure of the lung and oesophagus during whole-body irradiation with cobalt-60 gamma rays the dose rate delivered to the lungs and the neck is diminished by means of a filter. Because of its special shape, sternum and columna vertebralis obtain the unreduced dose. The filter is constructed for irradiation in antero-posterior direction. A fixed position of the patient is not necessary.

  19. Radiation dose reduction using a CdZnTe-based computed tomography system: Comparison to flat-panel detectors

    SciTech Connect

    Le, Huy Q.; Ducote, Justin L.; Molloi, Sabee

    2010-03-15

    Purpose: Although x-ray projection mammography has been very effective in early detection of breast cancer, its utility is reduced in the detection of small lesions that are occult or in dense breasts. One drawback is that the inherent superposition of parenchymal structures makes visualization of small lesions difficult. Breast computed tomography using flat-panel detectors has been developed to address this limitation by producing three-dimensional data while at the same time providing more comfort to the patients by eliminating breast compression. Flat panels are charge integrating detectors and therefore lack energy resolution capability. Recent advances in solid state semiconductor x-ray detector materials and associated electronics allow the investigation of x-ray imaging systems that use a photon counting and energy discriminating detector, which is the subject of this article. Methods: A small field-of-view computed tomography (CT) system that uses CdZnTe (CZT) photon counting detector was compared to one that uses a flat-panel detector for different imaging tasks in breast imaging. The benefits afforded by the CZT detector in the energy weighting modes were investigated. Two types of energy weighting methods were studied: Projection based and image based. Simulation and phantom studies were performed with a 2.5 cm polymethyl methacrylate (PMMA) cylinder filled with iodine and calcium contrast objects. Simulation was also performed on a 10 cm breast specimen. Results: The contrast-to-noise ratio improvements as compared to flat-panel detectors were 1.30 and 1.28 (projection based) and 1.35 and 1.25 (image based) for iodine over PMMA and hydroxylapatite over PMMA, respectively. Corresponding simulation values were 1.81 and 1.48 (projection based) and 1.85 and 1.48 (image based). Dose reductions using the CZT detector were 52.05% and 49.45% for iodine and hydroxyapatite imaging, respectively. Image-based weighting was also found to have the least beam

  20. Radiation dose reduction using a CdZnTe-based computed tomography system: Comparison to flat-panel detectors

    PubMed Central

    Le, Huy Q.; Ducote, Justin L.; Molloi, Sabee

    2010-01-01

    Purpose: Although x-ray projection mammography has been very effective in early detection of breast cancer, its utility is reduced in the detection of small lesions that are occult or in dense breasts. One drawback is that the inherent superposition of parenchymal structures makes visualization of small lesions difficult. Breast computed tomography using flat-panel detectors has been developed to address this limitation by producing three-dimensional data while at the same time providing more comfort to the patients by eliminating breast compression. Flat panels are charge integrating detectors and therefore lack energy resolution capability. Recent advances in solid state semiconductor x-ray detector materials and associated electronics allow the investigation of x-ray imaging systems that use a photon counting and energy discriminating detector, which is the subject of this article. Methods: A small field-of-view computed tomography (CT) system that uses CdZnTe (CZT) photon counting detector was compared to one that uses a flat-panel detector for different imaging tasks in breast imaging. The benefits afforded by the CZT detector in the energy weighting modes were investigated. Two types of energy weighting methods were studied: Projection based and image based. Simulation and phantom studies were performed with a 2.5 cm polymethyl methacrylate (PMMA) cylinder filled with iodine and calcium contrast objects. Simulation was also performed on a 10 cm breast specimen. Results: The contrast-to-noise ratio improvements as compared to flat-panel detectors were 1.30 and 1.28 (projection based) and 1.35 and 1.25 (image based) for iodine over PMMA and hydroxylapatite over PMMA, respectively. Corresponding simulation values were 1.81 and 1.48 (projection based) and 1.85 and 1.48 (image based). Dose reductions using the CZT detector were 52.05% and 49.45% for iodine and hydroxyapatite imaging, respectively. Image-based weighting was also found to have the least beam

  1. [Reduction of radiation dose to the worker in preparing the radiopharmaceutical solution by a simple shielding equipment].

    PubMed

    Miyazaki, Y; Inoue, H; Shiozaki, J; Higuchi, Y; Fujioka, M; Kawaguchi, K; Miyanaga, M; Aburano, T

    1987-01-01

    In order to reduce radiation dose to the hands of examiners who prepare and aspirate radiopharmaceuticals, we made a prototype of simplified manually-operated dispense system, which the syringe and the vial shield with lead were set in the small box made of lead and lead glass. The result showed that our dispense system allowed substantial reduction of radiation dose to the hands and rapid preparation of radiopharmaceuticals compared with the conventional lead shield syringe system, and allowed closer operation, smaller dead volume and lower cost compared with the conventional automatic system.

  2. Dose-Dependent Effect of Granulocyte Transfusions in Hematological Patients with Febrile Neutropenia

    PubMed Central

    Di Blasi, Roberta; Orlando, Nicoletta; Fianchi, Luana; Zini, Gina; Sica, Simona; De Stefano, Valerio; Pagano, Livio

    2016-01-01

    It is still under debate whether granulocyte transfusions (GTs) substantially increase survival in patients with febrile neutropenia. We retrospectively examined data relative to 96 patients with hematological malignancies receiving 491 GTs during 114 infectious episodes (IE). Patients were grouped according to the median doses of granulocytes transfused during the infectious episode (low-dose group: <1.5-x108 cells/Kg; standard-dose group: 1.5–3.0x108 cells/Kg and high-dose group: >3.0x108 cells/Kg). The impact of clinical, microbiological and GT-related variables on the infection-related mortality (IRM) was investigated. The IRM was not influenced by the number of GTs or by the total amount of granulocytes received, whereas a dose-related effect of the median dose received for IE was detected at univariate analysis (IRM of 18.4% in the standard-dose group, 44.4% in the low-dose group and 48.4% in the high-dose group, p = 0.040) and confirmed at multivariate analysis (OR 3.7, IC 95% 1.5–8.9; 0.004 for patients not receiving standard doses of GTs). Moreover, patients receiving GTs at doses lower or greater than standard had increased risk for subsequent ICU admission and reduced overall survival. The dose-related effect of GTs was confirmed in bacterial but not in fungal infections. Preliminary findings obtained from a subgroup of patients candidate to GTs revealed that levels of inflammatory response mediators increase in a dose-related manner after GTs, providing a possible explanation for the detrimental effect exerted by high-dose transfusions. GTs can constitute a valuable tool to improve the outcome of infections in neutropenic patients, provided that adequate recipient-tailored doses are supplied. Further investigations of the immunomodulatory effects of GTs are recommended. PMID:27487075

  3. Optimal dose of gemcitabine for the treatment of biliary tract or pancreatic cancer in patients with liver dysfunction.

    PubMed

    Shibata, Takashi; Ebata, Tomoki; Fujita, Ken-ichi; Shimokata, Tomoya; Maeda, Osamu; Mitsuma, Ayako; Sasaki, Yasutsuna; Nagino, Masato; Ando, Yuichi

    2016-02-01

    A clear consensus does not exist about whether the initial dose of gemcitabine, an essential anticancer antimetabolite, should be reduced in patients with liver dysfunction. Adult patients with biliary tract or pancreatic cancer were divided into three groups according to whether they had mild, moderate, or severe liver dysfunction, evaluated on the basis of serum bilirubin and liver transaminase levels at baseline. As anticancer treatment, gemcitabine at a dose of 800 or 1000 mg/m(2) was given as an i.v. infusion once weekly for 3 weeks of a 4-week cycle. The patients were prospectively evaluated for adverse events during the first cycle, and the pharmacokinetics of gemcitabine and its inactive metabolite, difluorodeoxyuridine, were studied to determine the optimal initial dose of gemcitabine as monotherapy according to the severity of liver dysfunction. A total of 15 patients were studied. Liver dysfunction was mild in one patient, moderate in six, and severe in eight. All 15 patients had been undergoing biliary drainage for obstructive jaundice when they received gemcitabine. Grade 3 cholangitis developed in one patient with moderate liver dysfunction who received gemcitabine at the dose level of 1000 mg/m(2). No other patients had severe treatment-related adverse events resulting in the omission or discontinuation of gemcitabine treatment. The plasma concentrations of gemcitabine and difluorodeoxyuridine were similar among the groups. An initial dose reduction of gemcitabine as monotherapy for the treatment of biliary tract or pancreatic cancers is not necessary for patients with hyperbilirubinemia, provided that obstructive jaundice is well managed. (Clinical trial registration no. UMIN000005363.)

  4. SU-C-207-05: A Comparative Study of Noise-Reduction Algorithms for Low-Dose Cone-Beam Computed Tomography

    SciTech Connect

    Mukherjee, S; Yao, W

    2015-06-15

    Purpose: To study different noise-reduction algorithms and to improve the image quality of low dose cone beam CT for patient positioning in radiation therapy. Methods: In low-dose cone-beam CT, the reconstructed image is contaminated with excessive quantum noise. In this study, three well-developed noise reduction algorithms namely, a) penalized weighted least square (PWLS) method, b) split-Bregman total variation (TV) method, and c) compressed sensing (CS) method were studied and applied to the images of a computer–simulated “Shepp-Logan” phantom and a physical CATPHAN phantom. Up to 20% additive Gaussian noise was added to the Shepp-Logan phantom. The CATPHAN phantom was scanned by a Varian OBI system with 100 kVp, 4 ms and 20 mA. For comparing the performance of these algorithms, peak signal-to-noise ratio (PSNR) of the denoised images was computed. Results: The algorithms were shown to have the potential in reducing the noise level for low-dose CBCT images. For Shepp-Logan phantom, an improvement of PSNR of 2 dB, 3.1 dB and 4 dB was observed using PWLS, TV and CS respectively, while for CATPHAN, the improvement was 1.2 dB, 1.8 dB and 2.1 dB, respectively. Conclusion: Penalized weighted least square, total variation and compressed sensing methods were studied and compared for reducing the noise on a simulated phantom and a physical phantom scanned by low-dose CBCT. The techniques have shown promising results for noise reduction in terms of PSNR improvement. However, reducing the noise without compromising the smoothness and resolution of the image needs more extensive research.

  5. Image quality and dose optimization using novel x-ray source filters tailored to patient size

    NASA Astrophysics Data System (ADS)

    Toth, Thomas L.; Cesmeli, Erdogan; Ikhlef, Aziz; Horiuchi, Tetsuya

    2005-04-01

    The expanding set of CT clinical applications demands increased attention to obtaining the maximum image quality at the lowest possible dose. Pre-patient beam shaping filters provide an effective means to improve dose utilization. In this paper we develop and apply characterization methods that lead to a set of filters appropriately matched to the patient. We developed computer models to estimate image noise and a patient size adjusted CTDI dose. The noise model is based on polychromatic X-ray calculations. The dose model is empirically derived by fitting CTDI style dose measurements for a demographically representative set of phantom sizes and shapes with various beam shaping filters. The models were validated and used to determine the optimum IQ vs dose for a range of patient sizes. The models clearly show that an optimum beam shaping filter exists as a function of object diameter. Based on noise and dose alone, overall dose efficiency advantages of 50% were obtained by matching the filter shape to the size of the object. A set of patient matching filters are used in the GE LightSpeed VCT and Pro32 to provide a practical solution for optimum image quality at the lowest possible dose over the range of patient sizes and clinical applications. Moreover, these filters mark the beginning of personalized medicine where CT scanner image quality and radiation dose utilization is truly individualized and optimized to the patient being scanned.

  6. Effect of low dose nicotinic acid on hyperphosphatemia in patients with end stage renal disease

    PubMed Central

    Zahed, N. S.; Zamanifar, N.; Nikbakht, H.

    2016-01-01

    Hyperphosphatemia is a risk factor for ectopic calcification and coronary artery diseases in end stage renal diseases (ESRD). The aim of this study was to assess the effect of low-dose nicotinic acid on hyperphosphatemia in patients with ESRD. This randomized, double-blind clinical trial was done on 70 ESRD patients with serum phosphoure ≥5.5 mg/dl. Patients were randomly divided into two equal groups (n = 35) and the intervention group received niacin 25 mg/day as the initial dose. After 4 weeks, in patients who did not respond to treatment, niacin dose was increased up to 50 mg/dl. At the end of week 8, in case there was no treatment effect, the dose was raised to 100 mg/day. The appropriate response to treatment was defined as serum phosphorous level reductions <5.5 mg/dl. The age was 50.5 ± 14.3 years and duration of dialysis 5.1 ± 5.3 months. In the niacin group, mean phosphorus level decreased from 6.7 ± 0.84 mg/dl at the end of the 1st month to 5.8 ± 1.0 mg/dl at the end of the 2nd month and to 4.4 ± 1.4 mg/dl at the end of the 3rd month (P = 0.004). In the placebo group, mean phosphorus level increased from 6.5 ± 1.2 mg/dl to 7.2 ± 0.91 mg/dl at the end of the 3rd month (P = 0.006). In the niacin group, high density lipoprotein (HDL) increased significantly from 45.00 ± 14.9 to 47.2 ± 11.6 (P = 0.009). We conclude that niacin (100 mg/day) decreased phosphorus serum level and increased HDL serum level in patients on dialysis. PMID:27512294

  7. A spatially encoded dose difference maximal intensity projection map for patient dose evaluation: A new first line patient quality assurance tool

    SciTech Connect

    Hu Weigang; Graff, Pierre; Boettger, Thomas; Pouliot, Jean; and others

    2011-04-15

    Purpose: To develop a spatially encoded dose difference maximal intensity projection (DD-MIP) as an online patient dose evaluation tool for visualizing the dose differences between the planning dose and dose on the treatment day. Methods: Megavoltage cone-beam CT (MVCBCT) images acquired on the treatment day are used for generating the dose difference index. Each index is represented by different colors for underdose, acceptable, and overdose regions. A maximal intensity projection (MIP) algorithm is developed to compress all the information of an arbitrary 3D dose difference index into a 2D DD-MIP image. In such an algorithm, a distance transformation is generated based on the planning CT. Then, two new volumes representing the overdose and underdose regions of the dose difference index are encoded with the distance transformation map. The distance-encoded indices of each volume are normalized using the skin distance obtained on the planning CT. After that, two MIPs are generated based on the underdose and overdose volumes with green-to-blue and green-to-red lookup tables, respectively. Finally, the two MIPs are merged with an appropriate transparency level and rendered in planning CT images. Results: The spatially encoded DD-MIP was implemented in a dose-guided radiotherapy prototype and tested on 33 MVCBCT images from six patients. The user can easily establish the threshold for the overdose and underdose. A 3% difference between the treatment and planning dose was used as the threshold in the study; hence, the DD-MIP shows red or blue color for the dose difference >3% or {<=}3%, respectively. With such a method, the overdose and underdose regions can be visualized and distinguished without being overshadowed by superficial dose differences. Conclusions: A DD-MIP algorithm was developed that compresses information from 3D into a single or two orthogonal projections while hinting the user whether the dose difference is on the skin surface or deeper.

  8. Noise reduction with low dose CT data based on a modified ROF model.

    PubMed

    Zhu, Yining; Zhao, Mengliu; Zhao, Yunsong; Li, Hongwei; Zhang, Peng

    2012-07-30

    In order to reduce the radiation exposure caused by Computed Tomography (CT) scanning, low dose CT has gained much interest in research as well as in industry. One fundamental difficulty for low dose CT lies in its heavy noise pollution in the raw data which leads to quality deterioration for reconstructed images. In this paper, we propose a modified ROF model to denoise low dose CT measurement data in light of Poisson noise model. Experimental results indicate that the reconstructed CT images based on measurement data processed by our model are in better quality, compared to the original ROF model or bilateral filtering.

  9. Low-dose interleukin-2 fosters a dose-dependent regulatory T cell tuned milieu in T1D patients.

    PubMed

    Rosenzwajg, Michelle; Churlaud, Guillaume; Mallone, Roberto; Six, Adrien; Dérian, Nicolas; Chaara, Wahiba; Lorenzon, Roberta; Long, S Alice; Buckner, Jane H; Afonso, Georgia; Pham, Hang-Phuong; Hartemann, Agnès; Yu, Aixin; Pugliese, Alberto; Malek, Thomas R; Klatzmann, David

    2015-04-01

    Most autoimmune diseases (AID) are linked to an imbalance between autoreactive effector T cells (Teffs) and regulatory T cells (Tregs). While blocking Teffs with immunosuppression has long been the only therapeutic option, activating/expanding Tregs may achieve the same objective without the toxicity of immunosuppression. We showed that low-dose interleukin-2 (ld-IL-2) safely expands/activates Tregs in patients with AID, such HCV-induced vasculitis and Type 1 Diabetes (T1D). Here we analyzed the kinetics and dose-relationship of IL-2 effects on immune responses in T1D patients. Ld-IL-2 therapy induced a dose-dependent increase in CD4(+)Foxp3(+) and CD8(+)Foxp3(+) Treg numbers and proportions, the duration of which was markedly dose-dependent. Tregs expressed enhanced levels of activation markers, including CD25, GITR, CTLA-4 and basal pSTAT5, and retained a 20-fold higher sensitivity to IL-2 than Teff and NK cells. Plasma levels of regulatory cytokines were increased in a dose-dependent manner, while cytokines linked to Teff and Th17 inflammatory cells were mostly unchanged. Global transcriptome analyses showed a dose-dependent decrease in immune response signatures. At the highest dose, Teff responses against beta-cell antigens were suppressed in all 4 patients tested. These results inform of broader changes induced by ld-IL-2 beyond direct effects on Tregs, and relevant for further development of ld-IL-2 for therapy and prevention of T1D, and other autoimmune and inflammatory diseases.

  10. Evaluation of Effective Dose from CT Scans for Overweight and Obese Adult Patients Using the VirtualDose Software.

    PubMed

    Liang, Baohui; Gao, Yiming; Chen, Zhi; Xu, X George

    2016-05-30

    This paper evaluates effective dose (ED) of overweight and obese patients who undergo body computed tomography (CT) examinations. ED calculations were based on tissue weight factors in the International Commission on Radiological Protection Publication 103 (ICRP 103). ED per unit dose length product (DLP) are reported as a function of the tube voltage, body mass index (BMI) of patient. The VirtualDose software was used to calculate ED for male and female obese phantoms representing normal weight, overweight, obese 1, obese 2 and obese 3 patients. Five anatomic regions (chest, abdomen, pelvis, abdomen/pelvis and chest/abdomen/pelvis) were investigated for each phantom. The conversion factors were computed from the DLP, and then compared with data previously reported by other groups. It was observed that tube voltage and BMI are the major factors that influence conversion factors of obese patients, and that ED computed using ICRP 103 tissue weight factors were 24% higher for a CT chest examination and 21% lower for a CT pelvis examination than the ED using ICRP 60 factors. For body CT scans, increasing the tube voltage from 80 to 140 kVp would increase the conversion factors by as much as 19-54% depending on the patient's BMI. Conversion factor of female patients was ~7% higher than the factors of male patients. DLP and conversion factors were used to estimate ED, where conversion factors depended on tube voltage, sex, BMI and tissue weight factors. With increasing number of obese individuals, using size-dependence conversion factors will improve accuracy, in estimating patient radiation dose.

  11. Dose reduction in orthodontic lateral cephalography: dosimetric evaluation of a novel cephalographic thyroid protector (CTP) and anatomical cranial collimation (ACC)

    PubMed Central

    Rottke, D; van der Stelt, P F; Berkhout, W E R

    2015-01-01

    Objectives: To test the dose-reducing capabilities of a novel thyroid protection device and a recently introduced cranial collimator to be used in orthodontic lateral cephalography. Methods: Cephalographic thyroid protector (CTP) was designed to shield the thyroid while leaving the cervical vertebrae depicted. Using a RANDO® head phantom (The Phantom Laboratory, Salem, NY) equipped with dosemeters and a Proline XC (Planmeca, Helsinki, Finland) cephalograph, lateral cephalograms were taken, and the effective dose (ED) was calculated for four protocols: (1) without shielding; (2) with CTP; (3) with CTP and anatomical cranial collimator (ACC); and (4) with a thyroid collar (TC). Results: The ED for the respective protocols was (1) 8.51; (2) 5.39; (3) 3.50; and (4) 4.97 µSv. The organ dose for the thyroid was reduced from 30.17 to 4.50 µSv in Protocols 2 and 3 and to 3.33 µSv in Protocol 4. Conclusions: The use of just the CTP (Protocol 2) resulted in a 36.8% reduction of the ED of a lateral cephalogram. This was comparable to the classical TC (Protocol 4). A 58.8% reduction of the ED was obtained when combining CTP and ACC (Protocol 3). The dose to the radiosensitive thyroid gland was reduced by 85% in Protocols 2 and 3 and by 89% in Protocol 4. PMID:25564885

  12. Reduction in mutation frequency by very low-dose gamma irradiation of Drosophila melanogaster germ cells.

    PubMed

    Ogura, Keiji; Magae, Junji; Kawakami, Yasushi; Koana, Takao

    2009-01-01

    To determine whether the linear no-threshold (LNT) model for stochastic effects of ionizing radiation is applicable to very low-dose radiation at a low dose rate, we irradiated immature male germ cells of the fruit fly, Drosophila melanogaster, with several doses of (60)Co gamma rays at a dose rate of 22.4 mGy/h. Thereafter, we performed the sex-linked recessive lethal mutation assay by mating the irradiated males with nonirradiated females. The mutation frequency in the group irradiated with 500 microGy was found to be significantly lower than that in the control group (P < 0.01), whereas in the group subjected to 10 Gy irradiation, the mutation frequency was significantly higher than that in the control group (P < 0.03). A J-shaped dose-response relationship was evident. Molecular experiments using DNA microarray and quantitative reverse transcription PCR indicated that several genes known to be expressed in response to heat or chemical stress and grim, a positive regulator of apoptosis, were up-regulated immediately after irradiation with 500 microGy. The involvement of an apoptosis function in the non-linear dose-response relationship was suggested.

  13. Radiation doses to paediatric patients and comforters undergoing chest X rays.

    PubMed

    Sulieman, A; Vlychou, M; Tsougos, I; Theodorou, K

    2011-09-01

    Pneumonia is an important cause of hospital admission among children in the developed world and it is estimated to be responsible for 3-18 % of all paediatric admissions. Chest X ray is an important examination for pneumonia diagnosis and for evaluation of complications. This study aims to determine the entrance surface dose (ESD), organ, effective doses and propose a local diagnostic reference level. The study was carried out at the university hospital of Larissa, Greece. Patients were divided into three groups: organ and effective doses were estimated using National Radiological Protection Board software. The ESD was determined by thermoluminescent dosemeters for 132 children and 76 comforters. The average ESD value was 55 ± 8 µGy. The effective dose for patients was 11.2 ± 5 µSv. The mean radiation dose for comforter is 22 ± 3 µGy. The radiation dose to the patients is well within dose constraint, in the light of the current practice.

  14. Effective Dose Reduction to Cardiac Structures Using Protons Compared With 3DCRT and IMRT in Mediastinal Hodgkin Lymphoma

    SciTech Connect

    Hoppe, Bradford S.; Flampouri, Stella; Su Zhong; Latif, Naeem; Dang, Nam H.; Lynch, James; Joyce, Michael; Sandler, Eric

    2012-10-01

    Purpose: We investigated the dosimetric impact of proton therapy (PT) on various cardiac subunits in patients with Hodgkin lymphoma (HL). Methods and Materials: From June 2009 through December 2010, 13 patients were enrolled on an institutional review board-approved protocol for consolidative involved-node radiotherapy (INRT) for HL. Three separate treatment plans were developed prospectively by using three-dimensional conformal radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT), and PT. Cardiac subunits were retrospectively contoured on the 11 patients with intravenous-contrast simulation scans, and the doses were calculated for all treatment plans. A Wilcoxon paired test was performed to evaluate the statistical significance (p < 0.05) of 3DCRT and IMRT compared with PT. Results: The mean heart doses were 21 Gy, 12 Gy, and 8 Gy (relative biologic effectiveness [RBE]) with 3DCRT, IMRT, and PT, respectively. Compared with 3DCRT and IMRT, PT reduced the mean doses to the left and right atria; the left and right ventricles; the aortic, mitral, and tricuspid valves; and the left anterior descending, left circumflex, and right circumflex coronary arteries. Conclusions: Compared with 3DCRT and IMRT, PT reduced the radiation doses to all major cardiac subunits. Limiting the doses to these structures should translate into lower rates of cardiac toxicities.

  15. Reduction of bacterial titers by low-dose aspirin in experimental aortic valve endocarditis.

    PubMed Central

    Nicolau, D P; Freeman, C D; Nightingale, C H; Quintiliani, R; Coe, C J; Maderazo, E G; Cooper, B W

    1993-01-01

    Using a rabbit model of Staphylococcus aureus endocarditis, we studied the effects of aspirin on the natural progression of this infection. Compared with untreated animals, the aspirin-treated animals showed a 30% (P = 0.11) reduction in the weight of the vegetations and an 84% (P = 0.03) reduction in the bacterial titer of the vegetations. PMID:8454370

  16. Efficacy of low-dose cinacalcet on alternate days for the treatment of secondary hyperparathyroidism in hemodialysis patients: a single-center study

    PubMed Central

    Gojaseni, Pongsathorn; Pattarathitinan, Dolnapa; Chittinandana, Anutra

    2017-01-01

    Introduction Cinacalcet is effective in reducing serum parathyroid hormone (PTH) in patients with secondary hyperparathyroidism (HPT). This study focused on testing whether a prescription of low-dose cinacalcet on alternate days could be an option for treatment of secondary HPT. Materials and methods A retrospective clinical study was conducted on chronic maintenance hemodialysis patients. Patients with secondary HPT who received cinacalcet at a starting dose of 25 mg on alternate days were reviewed (low-dose group). Patients who were being treated with a standard dose of cinacalcet in the same period of time were selected as the control group. The primary outcome was difference in the percentage of patients achieving >30% reduction of intact parathyroid hormone (iPTH) levels at 16 weeks. The changes of serum iPTH and other biochemical data were also tested. Results A total of 30 patients (16 low doses and 14 controls) took part in the study. Baseline iPTH levels in the low-dose and control group were 1,065.9±477.7 and 1,214.1±497.6 pg/mL, respectively (p=0.413). The analysis showed that the percentage of patients who achieved the primary outcome showed little or no difference (33.3% in the low-dose group compared with 38.5% in the control group, p=1.0). Serum iPTH reduction during 16 weeks of study period in the low-dose and control group was 253.5±316.1 and 243.4±561.3 pg/mL, respectively (p=0.957). There was no difference in the adverse events between both groups. Conclusion Among patients with secondary HPT, initial treatment with cinacalcet 25 mg on alternate days can decrease serum PTH levels. The role of low-dose cinacalcet in secondary HPT should be further determined in large-scale, randomized controlled trials. PMID:28223837

  17. A novel treatment planning methodology for high dose (166)Ho-DOTMP therapy in patients with multiple myeloma

    NASA Astrophysics Data System (ADS)

    McCullough, Steven Patrick

    2000-09-01

    Bone marrow ablation, i.e., the complete sterilization of the active bone marrow, followed by bone marrow transplantation (BMT) is a comment treatment of hematological malignancies. The use of targeted bone- seeking radiopharmaceuticals to selectively deliver radiation to the adjacent bone marrow cavities while sparing normal tissues is a promising technique. Current radiopharmaceutical treatment planning methods do not properly compensate for the patient-specific variable distribution of radioactive material within the skeleton. To improve the current method of internal dosimetry, novel methods for measuring the radiopharmaceutical distribution within the skeleton were developed. 99mTc-MDP was proven as an adequate surrogate for measuring 166Ho-DOTMP skeletal uptake and biodistribution, allowing these measures to be obtained faster, safer, and with higher spatial resolution. This translates directly into better measurements of the radiation dose distribution within the bone marrow. The resulting bone marrow dose-volume histograms allow prediction of the patient disease response where conventional organ scale dosimetry failed. They indicate that complete remission is only achieved when greater than 90% of the bone marrow receives at least 30 Gy. Comprehensive treatment planning requires combining target and non-target organ dosimetry. Organs in the urinary tract were of special concern. The kidney dose is primarily dependent upon the mean transit time of 166 Ho-DOTMP through the kidney. Deconvolution analysis of renograms predicted a mean transit time of 2.6 minutes for 166Ho- DOTMP. The radiation dose to the urinary bladder wall is dependent upon numerous factors including patient hydration and void schedule. For beta-emitting isotopes such as 166Ho, reduction of the bladder wall dose is best accomplished through good patient hydration and ensuring a partially full bladder at the time of injection. Encouraging the patient to void frequently, or catheterizing the

  18. Pharmacokinetics of high-dose metoclopramide in cancer patients.

    PubMed

    McGovern, E M; Grevel, J; Bryson, S M

    1986-01-01

    The introduction of new cytotoxic drug regimens has been associated with an increase in the incidence and severity of adverse effects. This in turn has highlighted the need for more effective adjuvant therapy. The use of metoclopramide for the prophylaxis of nausea and vomiting, in high intravenous doses (50 to 1000 mg), has become established since 1981. As a lipid-soluble drug, metoclopramide has a large volume of distribution. The reported mean values after high doses range between 2.8 and 4.6 L/kg. The mean values for total body clearance and terminal half-life range from 0.31 to 0.69 L/kg/h and from 4.5 to 8.8 hours, respectively. The values of these pharmacokinetic parameters are essentially similar to those obtained after conventional doses (less than 50mg). Pharmacokinetic parameters appear unaffected by age, although no high-dose study has been conducted in children. Bodyweight is apparently correlated with clearance. An influence of renal function indices on terminal half-life and clearance has been shown, which is rather surprising since renal clearance accounts for only 20% of the total clearance. No thorough investigations exist which examine the influence of hepatic disease, cancer type and cytotoxic drug regimen on the disposition of metoclopramide. A relationship between dose (or concentration) and therapeutic or adverse effects of metoclopramide is outlined. The therapeutic benefit of high doses (up to 14 mg/kg) may be dependent on age, and on the combination of cytotoxic drugs. The advantages of high doses of metoclopramide are most apparent when the drug is used as protection against the adverse effects of high doses of cisplatin (greater than 60 mg/m2). Despite considerable pharmacokinetic variability, intravenous administration of high doses of metoclopramide is relatively safe due to its large therapeutic index.

  19. Phase I dose escalation study of high dose carfilzomib monotherapy for Japanese patients with relapsed or refractory multiple myeloma.

    PubMed

    Iida, Shinsuke; Tobinai, Kensei; Taniwaki, Masafumi; Shumiya, Yoshihisa; Nakamura, Toru; Chou, Takaaki

    2016-11-01

    We conducted a multicenter, open-label Phase I study of single-agent carfilzomib in Japanese patients with relapsed or refractory multiple myeloma. The primary endpoints were tolerability and safety. Carfilzomib was administrated for 30 min on days 1, 2, 8, 9, 15, and 16 of a 28-day cycle. In cycle 1, doses for days 1 and 2 were 20 mg/m(2), followed by 45 or 56 mg/m(2). Three and four subjects were enrolled in the 20/45 mg/m(2) cohort and 20/56 mg/m(2) cohort. No dose-limiting toxicity was observed, and the tolerability of carfilzomib was confirmed. Pyrexia, hypertension, nausea and vomiting were considered as noteworthy adverse events (AE) when carfilzomib was administered at high doses. Moreover, pyrexia, blood creatinine increased, and body weight gain were observed as acute dose effects. These findings suggest that addition of dexamethasone is important to alleviate acute dose effect. The overall response rates of the 20/45 mg/m(2) and 20/56 mg/m(2) cohort were 66.7 % (two out of three) and 50 % (two out of four), respectively. Carfilzomib administrated at up to 20/56 mg/m(2) was well tolerated and seemed active in Japanese patients with relapsed or refractory multiple myeloma.

  20. Patient doses in {gamma}-intracoronary radiotherapy: The Radiation Burden Assessment Study

    SciTech Connect

    Thierens, Hubert . E-mail: hubert.thierens@Ughent.be; Reynaert, Nick; Bacher, Klaus; Eijkeren, Marc van; Taeymans, Yves

    2004-10-01

    Purpose: To determine accurately the radiation burden of both patients and staff from intracoronary radiotherapy (IRT) with {sup 192}Ir and to investigate the importance of IRT in the patient dose compared with interventional X-rays. Methods and materials: The Radiation Burden Assessment Study (RABAS) population consisted of 9 patients undergoing {gamma}-IRT after percutaneous transluminal coronary angioplasty and 14 patients undergoing percutaneous transluminal coronary angioplasty only as the control group. For each patient, the dose to the organs and tissues from the internal and external exposure was determined in detail by Monte Carlo N-particle simulations. Patient skin dose measurements with thermoluminescence dosimeters served as verification. Staff dosimetry was performed with electronic dosimeters, thermoluminescence dosimeters, and double film badge dosimetry. Results: With respect to the patient dose from IRT, the critical organs are the thymus (58 mGy), lungs (31 mGy), and esophagus (27 mGy). The mean effective dose from IRT was 8 mSv. The effective dose values from interventional X-rays showed a broad range (2-28 mSv), with mean values of 8 mSv for the IRT patients and 13 mSv for the control group. The mean dose received by the radiotherapist from IRT was 4 {mu}Sv/treatment. The doses to the other staff members were completely negligible. Conclusion: Our results have shown that the patient and personnel doses in {gamma}-IRT remain at an acceptable level. The patient dose from IRT was within the variations in dose from the accompanying interventional X-rays.

  1. Cannabidiol reverses the reduction in social interaction produced by low dose Delta(9)-tetrahydrocannabinol in rats.

    PubMed

    Malone, Daniel Thomas; Jongejan, Dennis; Taylor, David Alan

    2009-08-01

    While Delta(9)-tetrahydrocannabinol (THC) is the main psychoactive constituent of the cannabis plant, a non-psychoactive constituent is cannabidiol (CBD). CBD has been implicated as a potential treatment of a number of disorders including schizophrenia and epilepsy and has been included with THC in a 1:1 combination for the treatment of conditions such as neuropathic pain. This study investigated the effect of THC and CBD, alone or in combination, on some objective behaviours of rats in the open field. Pairs of rats were injected with CBD or vehicle followed by THC or vehicle and behaviour in the open field was assessed for 10 min. In vehicle pretreated rats THC (1 mg/kg) significantly reduced social interaction between rat pairs. Treatment with CBD had no significant effect alone, but pretreatment with CBD (20 mg/kg) reversed the THC-induced decreases in social interaction. A higher dose of THC (10 mg/kg) produced no significant effect on social interaction. However, the combination of high dose CBD and high dose THC significantly reduced social interaction between rat pairs, as well as producing a significant decrease in locomotor activity. This data suggests that CBD can reverse social withdrawal induced by low dose THC, but the combination of high dose THC and CBD impairs social interaction, possibly by decreasing locomotor activity.

  2. Low-Dose Naltrexone: A New Therapy Option for Complex Regional Pain Syndrome Type I Patients.

    PubMed

    Sturn, Kayla M; Collin, Michael

    2016-01-01

    Naltrexone (an opioid antagonist) has long been used in patients overcoming alcohol and opioid dependency. However, at doses one-tenth of those commonly prescribed for the above conditions, an unexpected effect occurs that aids in alleviating pain. Although there are currently no randomized clinical trials supporting the use of low-dose naltrexone, we present a case study describing the impact of compounding low-dose naltrexone that has dramatically improved the patient's pain symptoms which were refractory to other treatments.

  3. WE-A-18A-01: TG246 On Patient Dose From Diagnostic Radiation

    SciTech Connect

    Supanich, M; Dong, F; Andersson, J; Pavlicek, W; Bolch, W; Fetterly, K

    2014-06-15

    Radiation dose from diagnostic and interventional radiations continues to be a focus of the regulatory, accreditation and standards organizations in the US and Europe. A Joint AAPM/EFOMP effort has been underway in the past year — having the goal to assist the clinical medical physicist with communicating optional and varied approaches in estimating (and validating) patient dose. In particular, the tools provided by DICOM Radiation Dose Structured Reports, either by themselves or as part of a networked data repository of dose related information are a rich source of actionable information. The tools of the medical physicist have evolved to include using DICOM data in meaningful ways to look at patient dose with respect to imaging practices. In addition to how accurate or reproducible a dose value is (totally necessary and our traditional workspace) it is now being asked how reproducible (patient to patient, device to device) are the delivered doses (new tasking)? Clinical medical physicists are best equipped to assist our radiology and technologist colleagues with this effort. The purpose of this session is to review the efforts of TG246 - bringing forward a summary content of the TG246 Report including specific dose descriptors for CT and Fluoroscopy — particularly in a focus of leveraging the RDSR as a means for monitoring good practices ALARA. Additionally, rapidly evolving technologies for more refined dose estimates are now in use. These will be presented as they look to having highly patient specific dose estimates in automated use.

  4. Patient dose estimation from CT scans at the Mexican National Neurology and Neurosurgery Institute

    NASA Astrophysics Data System (ADS)

    Alva-Sánchez, Héctor; Reynoso-Mejía, Alberto; Casares-Cruz, Katiuzka; Taboada-Barajas, Jesús

    2014-11-01

    In the radiology department of the Mexican National Institute of Neurology and Neurosurgery, a dedicated institute in Mexico City, on average 19.3 computed tomography (CT) examinations are performed daily on hospitalized patients for neurological disease diagnosis, control scans and follow-up imaging. The purpose of this work was to estimate the effective dose received by hospitalized patients who underwent a diagnostic CT scan using typical effective dose values for all CT types and to obtain the estimated effective dose distributions received by surgical and non-surgical patients. Effective patient doses were estimated from values per study type reported in the applications guide provided by the scanner manufacturer. This retrospective study included all hospitalized patients who underwent a diagnostic CT scan between 1 January 2011 and 31 December 2012. A total of 8777 CT scans were performed in this two-year period. Simple brain scan was the CT type performed the most (74.3%) followed by contrasted brain scan (6.1%) and head angiotomography (5.7%). The average number of CT scans per patient was 2.83; the average effective dose per patient was 7.9 mSv; the mean estimated radiation dose was significantly higher for surgical (9.1 mSv) than non-surgical patients (6.0 mSv). Three percent of the patients had 10 or more brain CT scans and exceeded the organ radiation dose threshold set by the International Commission on Radiological Protection for deterministic effects of the eye-lens. Although radiation patient doses from CT scans were in general relatively low, 187 patients received a high effective dose (>20 mSv) and 3% might develop cataract from cumulative doses to the eye lens.

  5. Patient dose estimation from CT scans at the Mexican National Neurology and Neurosurgery Institute

    SciTech Connect

    Alva-Sánchez, Héctor

    2014-11-07

    In the radiology department of the Mexican National Institute of Neurology and Neurosurgery, a dedicated institute in Mexico City, on average 19.3 computed tomography (CT) examinations are performed daily on hospitalized patients for neurological disease diagnosis, control scans and follow-up imaging. The purpose of this work was to estimate the effective dose received by hospitalized patients who underwent a diagnostic CT scan using typical effective dose values for all CT types and to obtain the estimated effective dose distributions received by surgical and non-surgical patients. Effective patient doses were estimated from values per study type reported in the applications guide provided by the scanner manufacturer. This retrospective study included all hospitalized patients who underwent a diagnostic CT scan between 1 January 2011 and 31 December 2012. A total of 8777 CT scans were performed in this two-year period. Simple brain scan was the CT type performed the most (74.3%) followed by contrasted brain scan (6.1%) and head angiotomography (5.7%). The average number of CT scans per patient was 2.83; the average effective dose per patient was 7.9 mSv; the mean estimated radiation dose was significantly higher for surgical (9.1 mSv) than non-surgical patients (6.0 mSv). Three percent of the patients had 10 or more brain CT scans and exceeded the organ radiation dose threshold set by the International Commission on Radiological Protection for deterministic effects of the eye-lens. Although radiation patient doses from CT scans were in general relatively low, 187 patients received a high effective dose (>20 mSv) and 3% might develop cataract from cumulative doses to the eye lens.

  6. Perfusion Scintigraphy and Patient Selection for Lung Volume Reduction Surgery

    PubMed Central

    Chandra, Divay; Lipson, David A.; Hoffman, Eric A.; Hansen-Flaschen, John; Sciurba, Frank C.; DeCamp, Malcolm M.; Reilly, John J.; Washko, George R.

    2010-01-01

    Rationale: It is unclear if lung perfusion can predict response to lung volume reduction surgery (LVRS). Objectives: To study the role of perfusion scintigraphy in patient selection for LVRS. Methods: We performed an intention-to-treat analysis of 1,045 of 1,218 patients enrolled in the National Emphysema Treatment Trial who were non–high risk for LVRS and had complete perfusion scintigraphy results at baseline. The median follow-up was 6.0 years. Patients were classified as having upper or non–upper lobe–predominant emphysema on visual examination of the chest computed tomography and high or low exercise capacity on cardiopulmonary exercise testing at baseline. Low upper zone perfusion was defined as less than 20% of total lung perfusion distributed to the upper third of both lungs as measured on perfusion scintigraphy. Measurements and Main Results: Among 284 of 1,045 patients with upper lobe–predominant emphysema and low exercise capacity at baseline, the 202 with low upper zone perfusion had lower mortality with LVRS versus medical management (risk ratio [RR], 0.56; P = 0.008) unlike the remaining 82 with high perfusion where mortality was unchanged (RR, 0.97; P = 0.62). Similarly, among 404 of 1,045 patients with upper lobe–predominant emphysema and high exercise capacity, the 278 with low upper zone perfusion had lower mortality with LVRS (RR, 0.70; P = 0.02) unlike the remaining 126 with high perfusion (RR, 1.05; P = 1.00). Among the 357 patients with non–upper lobe–predominant emphysema (75 with low and 282 with high exercise capacity) there was no improvement in survival with LVRS and measurement of upper zone perfusion did not contribute new prognostic information. Conclusions: Compared with optimal medical management, LVRS reduces mortality in patients with upper lobe–predominant emphysema when there is low rather than high perfusion to the upper lung. PMID:20538961

  7. MO-E-17A-05: Individualized Patient Dosimetry in CT Using the Patient Dose (PATDOSE) Algorithm

    SciTech Connect

    Hernandez, A; Boone, J

    2014-06-15

    Purpose: Radiation dose to the patient undergoing a CT examination has been the focus of many recent studies. While CTDIvol and SSDE-based methods are important tools for patient dose management, the CT image data provides important information with respect to CT dose and its distribution. Coupled with the known geometry and output factors (kV, mAs, pitch, etc.) of the CT scanner, the CT dataset can be used directly for computing absorbed dose. Methods: The HU numbers in a patient's CT data set can be converted to linear attenuation coefficients (LACs) with some assumptions. With this (PAT-DOSE) method, which is not Monte Carlo-based, the primary and scatter dose are computed separately. The primary dose is computed directly from the geometry of the scanner, x-ray spectrum, and the known patient LACs. Once the primary dose has been computed to all voxels in the patient, the scatter dose algorithm redistributes a fraction of the absorbed primary dose (based on the HU number of each source voxel), and the methods here invoke both tissue attenuation and absorption and solid angle geometry. The scatter dose algorithm can be run N times to include Nth-scatter redistribution. PAT-DOSE was deployed using simple PMMA phantoms, to validate its performance against Monte Carlo-derived dose distributions. Results: Comparison between PAT-DOSE and MCNPX primary dose distributions showed excellent agreement for several scan lengths. The 1st-scatter dose distributions showed relatively higher-amplitude, long-range scatter tails for the PAT-DOSE algorithm then for MCNPX simulations. Conclusion: The PAT-DOSE algorithm provides a fast, deterministic assessment of the 3-D dose distribution in CT, making use of scanner geometry and the patient image data set. The preliminary implementation of the algorithm produces accurate primary dose distributions however achieving scatter distribution agreement is more challenging. Addressing the polyenergetic x-ray spectrum and spatially dependent

  8. Energy imparted-based estimates of the effect of z overscanning on adult and pediatric patient effective doses from multi-slice computed tomography

    SciTech Connect

    Theocharopoulos, Nicholas; Damilakis, John; Perisinakis, Kostas; Gourtsoyiannis, Nicholas

    2007-04-15

    In the present study effective dose values normalized to computed tomography dose index measured free in air were calculated for adult, newborn, 1, 5, 10 and 15 year old patients regarding scans of the head, chest, abdomen, pelvis, abdomen and pelvis, and trunk, using the energy imparted method. The effect of z overscanning on patient doses was accounted for, and normalized doses are provided for varying beam collimation, pitch and reconstruction slice width values. The contribution of overscanning depends on patient age, anatomic region imaged, acquisition and reconstruction settings. For a head scan it constitutes 15% of the adult effective dose and 24% of the effective dose to a newborn but for an abdomen scan it may be as high as 58% for a newborn and 31% for an adult. The ratios of normalized pediatric doses relative to that for adults for helical scans depend not only on age but also on acquisition and reconstruction parameters, because of variations in the relative distance between the primary beam and the radiosensitive tissues/organs of the body. Regarding scans of the trunk, pediatric doses are up to a factor of 2.5 times higher compared to adult doses (abdominal scans), whereas for scans of the head up to a factor of 1.5. Increasing the pitch value of helical scans while maintaining the same effective mAs setting, and hence noise levels, leads to an increase in patient doses which depends on age, body region, scan and reconstruction parameters. The % difference between doses at pitch 1.5 and pitch 1 is more pronounced in the abdominal region (14% increase for adults) and in young patients (31% in a newborn and 18% in a 10 year old patient) and it is minimal in head scans (4% increase in newborns and 1% in adults). If multiple body regions are to be imaged, doses to adults can be reduced by up to 15% and 36% to children by performing single long-range scans. Scanning adult patients at 100 kVp instead of 120 kVp, results in a 32% reduction in effective

  9. Assessing image quality and dose reduction of a new x-ray computed tomography iterative reconstruction algorithm using model observers

    SciTech Connect

    Tseng, Hsin-Wu Kupinski, Matthew A.; Fan, Jiahua; Sainath, Paavana; Hsieh, Jiang

    2014-07-15

    Purpose: A number of different techniques have been developed to reduce radiation dose in x-ray computed tomography (CT) imaging. In this paper, the authors will compare task-based measures of image quality of CT images reconstructed by two algorithms: conventional filtered back projection (FBP), and a new iterative reconstruction algorithm (IR). Methods: To assess image quality, the authors used the performance of a channelized Hotelling observer acting on reconstructed image slices. The selected channels are dense difference Gaussian channels (DDOG).A body phantom and a head phantom were imaged 50 times at different dose levels to obtain the data needed to assess image quality. The phantoms consisted of uniform backgrounds with low contrast signals embedded at various locations. The tasks the observer model performed included (1) detection of a signal of known location and shape, and (2) detection and localization of a signal of known shape. The employed DDOG channels are based on the response of the human visual system. Performance was assessed using the areas under ROC curves and areas under localization ROC curves. Results: For signal known exactly (SKE) and location unknown/signal shape known tasks with circular signals of different sizes and contrasts, the authors’ task-based measures showed that a FBP equivalent image quality can be achieved at lower dose levels using the IR algorithm. For the SKE case, the range of dose reduction is 50%–67% (head phantom) and 68%–82% (body phantom). For the study of location unknown/signal shape known, the dose reduction range can be reached at 67%–75% for head phantom and 67%–77% for body phantom case. These results suggest that the IR images at lower dose settings can reach the same image quality when compared to full dose conventional FBP images. Conclusions: The work presented provides an objective way to quantitatively assess the image quality of a newly introduced CT IR algorithm. The performance of the

  10. A novel method for interactive multi-objective dose-guided patient positioning

    NASA Astrophysics Data System (ADS)

    Haehnle, Jonas; Süss, Philipp; Landry, Guillaume; Teichert, Katrin; Hille, Lucas; Hofmaier, Jan; Nowak, Dimitri; Kamp, Florian; Reiner, Michael; Thieke, Christian; Ganswindt, Ute; Belka, Claus; Parodi, Katia; Küfer, Karl-Heinz; Kurz, Christopher

    2017-01-01

    In intensity-modulated radiation therapy (IMRT), 3D in-room imaging data is typically utilized for accurate patient alignment on the basis of anatomical landmarks. In the presence of non-rigid anatomical changes, it is often not obvious which patient position is most suitable. Thus, dose-guided patient alignment is an interesting approach to use available in-room imaging data for up-to-date dose calculation, aimed at finding the position that yields the optimal dose distribution. This contribution presents the first implementation of dose-guided patient alignment as multi-criteria optimization problem. User-defined clinical objectives are employed for setting up a multi-objective problem. Using pre-calculated dose distributions at a limited number of patient shifts and dose interpolation, a continuous space of Pareto-efficient patient shifts becomes accessible. Pareto sliders facilitate interactive browsing of the possible shifts with real-time dose display to the user. Dose interpolation accuracy is validated and the potential of multi-objective dose-guided positioning demonstrated for three head and neck (H&N) and three prostate cancer patients. Dose-guided positioning is compared to replanning for all cases. A delineated replanning CT served as surrogate for in-room imaging data. Dose interpolation accuracy was high. Using a 2 % dose difference criterion, a median pass-rate of 95.7% for H&N and 99.6% for prostate cases was determined in a comparison to exact dose calculations. For all patients, dose-guided positioning allowed to find a clinically preferable dose distribution compared to bony anatomy based alignment. For all H&N cases, mean dose to the spared parotid glands was below 26~\\text{Gy} (up to 27.5~\\text{Gy} with bony alignment) and clinical target volume (CTV) {{V}95 % } above 99.1% (compared to 95.1%). For all prostate patients, CTV {{V}95 % } was above 98.9% (compared to 88.5%) and {{V}50~\\text{Gy}} to the rectum below 50 % (compared to 56

  11. Radiation Dose Predicts for Biochemical Control in Intermediate-Risk Prostate Cancer Patients Treated With Low-Dose-Rate Brachytherapy

    SciTech Connect

    Ho, Alice Y.; Burri, Ryan J.; Cesaretti, Jamie A.; Stone, Nelson N.; Stock, Richard G.

    2009-09-01

    Purpose: To evaluate the influence of patient- and treatment-related factors on freedom from biochemical failure (FFbF) in patients with intermediate-risk prostate cancer. Methods and Materials: From a prospectively collected database of 2250 men treated at Mount Sinai Hospital from 1990 to 2004 with low-dose-rate brachytherapy for prostate cancer, 558 men with either one or more intermediate-risk features (prostate-specific antigen [PSA] level 10-20 ng/mL, Gleason score 7, or Stage T2b) were identified who had a minimum follow-up of 24 months and postimplant CT-based dosimetric analysis. Biologically effective dose (BED) values were calculated to compare doses from different isotopes and treatment regimens. Patients were treated with brachytherapy with or without hormone therapy and/or external-beam radiotherapy. Patient- and treatment-related factors were analyzed with respect to FFbF. The median follow-up was 60 months (range, 24-167 months). Biochemical failure was defined according to the Phoenix definition. Univariate analyses were used to determine whether any variable was predictive of FFbF. A two-sided p value of <0.05 was considered significant. Results: Overall, the actuarial FFbF at 10 years was 86%. Dose (BED <150 Gy{sub 2} vs. {>=}150 Gy{sub 2}) was the only significant predictor of FFbF (p < 0.001). None of the other variables (PSA, external-beam radiotherapy, Gleason score, treatment type, hormones, stage, and number of risk factors) was found to be a statistically significant predictor of 10-year FFbF. Conclusions: Radiation dose is an important predictor of FFbF in intermediate-risk prostate cancer. Treatment should continue to be individualized according to presenting disease characteristics until results from Radiation Therapy Oncology Group trial 0232 become available.

  12. Patient-based estimation of organ dose for a population of 58 adult patients across 13 protocol categories

    SciTech Connect

    Sahbaee, Pooyan; Segars, W. Paul; Samei, Ehsan

    2014-07-15

    Purpose: This study aimed to provide a comprehensive patient-specific organ dose estimation across a multiplicity of computed tomography (CT) examination protocols. Methods: A validated Monte Carlo program was employed to model a common CT system (LightSpeed VCT, GE Healthcare). The organ and effective doses were estimated from 13 commonly used body and neurological CT examination. The dose estimation was performed on 58 adult computational extended cardiac-torso phantoms (35 male, 23 female, mean age 51.5 years, mean weight 80.2 kg). The organ dose normalized by CTDI{sub vol} (h factor) and effective dose normalized by the dose length product (DLP) (k factor) were calculated from the results. A mathematical model was derived for the correlation between the h and k factors with the patient size across the protocols. Based on this mathematical model, a dose estimation iPhone operating system application was designed and developed to be used as a tool to estimate dose to the patients for a variety of routinely used CT examinations. Results: The organ dose results across all the protocols showed an exponential decrease with patient body size. The correlation was generally strong for the organs which were fully or partially located inside the scan coverage (Pearson sample correlation coefficient (r) of 0.49). The correlation was weaker for organs outside the scan coverage for which distance between the organ and the irradiation area was a stronger predictor of dose to the organ. For body protocols, the effective dose before and after normalization by DLP decreased exponentially with increasing patient's body diameter (r > 0.85). The exponential relationship between effective dose and patient's body diameter was significantly weaker for neurological protocols (r < 0.41), where the trunk length was a slightly stronger predictor of effective dose (0.15 < r < 0.46). Conclusions: While the most accurate estimation of a patient dose requires specific modeling of the patient

  13. Cone beam CT with zonal filters for simultaneous dose reduction, improved target contrast and automated set-up in radiotherapy.

    PubMed

    Moore, C J; Marchant, T E; Amer, A M

    2006-05-07

    Cone beam CT (CBCT) using a zonal filter is introduced. The aims are reduced concomitant imaging dose to the patient, simultaneous control of body scatter for improved image quality in the tumour target zone and preserved set-up detail for radiotherapy. Aluminium transmission diaphragms added to the CBCT x-ray tube of the Elekta Synergytrade mark linear accelerator produced an unattenuated beam for a central "target zone" and a partially attenuated beam for an outer "set-up zone". Imaging doses and contrast noise ratios (CNR) were measured in a test phantom for transmission diaphragms 12 and 24 mm thick, for 5 and 10 cm long target zones. The effect on automatic registration of zonal CBCT to conventional CT was assessed relative to full-field and lead-collimated images of an anthropomorphic phantom. Doses along the axis of rotation were reduced by up to 50% in both target and set-up zones, and weighted dose (two thirds surface dose plus one third central dose) was reduced by 10-20% for a 10 cm long target zone. CNR increased by up to 15% in zonally filtered CBCT images compared to full-field images. Automatic image registration remained as robust as that with full-field images and was superior to CBCT coned down using lead-collimation. Zonal CBCT significantly reduces imaging dose and is expected to benefit radiotherapy through improved target contrast, required to assess target coverage, and wide-field edge detail, needed for robust automatic measurement of patient set-up error.

  14. Impact of adaptive statistical iterative reconstruction on radiation dose in evaluation of trauma patients

    PubMed Central

    Maxfield, Mark W.; Schuster, Kevin M.; McGillicuddy, Edward A.; Young, Calvin J.; Ghita, Monica; Bokhari, S.A. Jamal; Oliva, Isabel B.; Brink, James A.; Davis, Kimberly A.

    2013-01-01

    BACKGROUND A recent study showed that computed tomographic (CT) scans contributed 93% of radiation exposure of 177 patients admitted to our Level I trauma center. Adaptive statistical iterative reconstruction (ASIR) is an algorithm that reduces the noise level in reconstructed images and therefore allows the use of less ionizing radiation during CT scans without significantly affecting image quality. ASIR was instituted on all CT scans performed on trauma patients in June 2009. Our objective was to determine if implementation of ASIR reduced radiation dose without compromising patient outcomes. METHODS We identified 300 patients activating the trauma system before and after the implementation of ASIR imaging. After applying inclusion criteria, 245 charts were reviewed. Baseline demographics, presenting characteristics, number of delayed diagnoses, and missed injuries were recorded. The postexamination volume CT dose index (CTDIvol) and dose-length product (DLP)reported by the scanner for CT scans of the chest, abdomen, and pelvis and CT scans of the brain and cervical spine were recorded. Subjective image quality was compared between the two groups. RESULTS For CT scans of the chest, abdomen, and pelvis, the mean CTDIvol(17.1 mGy vs. 14.2 mGy; p < 0.001) and DLP (1,165 mGy·cm vs. 1,004 mGy·cm; p < 0.001) was lower for studies performed with ASIR. For CT scans of the brain and cervical spine, the mean CTDIvol(61.7 mGy vs. 49.6 mGy; p < 0.001) and DLP (1,327 mGy·cm vs. 1,067 mGy·cm; p < 0.001) was lower for studies performed with ASIR. There was no subjective difference in image quality between ASIR and non-ASIR scans. All CT scans were deemed of good or excellent image quality. There were no delayed diagnoses or missed injuries related to CT scanning identified in either group. CONCLUSION Implementation of ASIR imaging for CT scans performed on trauma patients led to a nearly 20% reduction in ionizing radiation without compromising outcomes or image quality

  15. Integrating COPD into Patient-Centered Hospital Readmissions Reduction Programs

    PubMed Central

    Krishnan, Jerry A.; Gussin, Hélène A.; Prieto-Centurion, Valentin; Sullivan, Jamie L.; Zaidi, Farhan; Thomashow, Byron M.

    2015-01-01

    About 1 in 5 patients hospitalized for exacerbations of chronic obstructive pulmonary disease (COPD) in the United States are readmitted within 30 days. The U.S. Centers for Medicare and Medicaid Services has recently expanded its Hospital Readmissions Reduction Program to financially penalize hospitals with higher than expected all-cause 30-day readmission rates following a hospitalization for COPD exacerbation. In October 2013, the COPD Foundation convened a multi-stakeholder National COPD Readmissions Summit to summarize our understanding of how to reduce hospital readmissions in patients hospitalized for COPD exacerbations. Over 225 individuals participated in the Summit, including patients, clinicians, health service researchers, policy makers and representatives of academic health care centers, industry, and payers. Summit participants recommend that programs to reduce hospital readmissions: 1) Include specific recommendations about how to promote COPD self-management skills training for patients and their caregivers; 2) Adequately address co-existing disorders common to COPD in care plans during and after hospitalizations; 3) Include an evaluation of adverse events when implementing strategies to reduce hospital readmissions; and 4) Develop a strategy (e.g., a learning collaboratory) to connect groups who are engaged in developing, testing, and implementing programs to reduce hospital readmissions for COPD and other conditions. PMID:25927076

  16. Dosimetry of dose distributions in radiotherapy of patients with surgical implants

    NASA Astrophysics Data System (ADS)

    Brożyna, Bogusław; Chełmiński, Krzysztof; Bulski, Wojciech; Giżyńska, Marta; Grochowska, Paulina; Walewska, Agnieszka; Zalewska, Marta; Kawecki, Andrzej; Krajewski, Romuald

    2014-11-01

    The investigation was performed in order to evaluate the use of Gafchromic EBT films for measurements of dose distributions created during radiotherapy in tissues surrounding titanium or resorbable implants used for joining and consolidating facial bones. Inhomogeneous dose distributions at implant-tissue interfaces can be the reason of normal tissue complications observed in radiotherapy patients after surgery with implants. The dose measured at a depth of 2.5 cm on contact surfaces, proximal and distal to the beam source, between the titanium implant and the phantom material was 109% and 92% respectively of the reference dose measured in a homogeneous phantom. For the resorbable implants the doses measured on the proximal and the distal contact surfaces were 102% and 101% respectively of the reference dose. The resorbable implants affect the homogeneity of dose distribution at a significantly lesser degree than the titanium implants. Gafchromic EBT films allowed for precise dose distribution measurements at the contact surfaces between tissue equivalent materials and implants. We measured doses at contact surfaces between titanium implants and RW3 phantom. We measured doses at contact surfaces between resorbable implants and RW3 phantom. We compared doses measured on contact surfaces and doses in homogeneous phantom. Doses at contact surfaces between RW3 phantom and titanium were distorted about 8-9%. Doses at RW3 phantom and resorbable implant contact surfaces were distorted about 2%.

  17. Relationship between dose of antithyroid drugs and adverse events in pediatric patients with Graves’ disease

    PubMed Central

    Yasuda, Kie; Miyoshi, Yoko; Tachibana, Makiko; Namba, Noriyuki; Miki, Kazunori; Nakata, Yukiko; Takano, Toru; Ozono, Keiichi

    2017-01-01

    Abstract. Graves’ disease (GD) accounts for a large proportion of pediatric hyperthyroidism, and the first-line treatment is antithyroid drug (ATD) therapy. Methimazole (MMI) is effective in most patients but is associated with significant adverse events (AEs). We reviewed the medical records of GD patients (n = 56) with onset age of <15 yr and investigated the relationship between MMI dose and AEs. The study population comprised 11 male and 45 female patients and the median age at diagnosis was 11 yr. All patients were initially treated with ATDs. Among the 52 patients initially treated with MMI, 20 received a low dose, and 32 received a high dose of MMI (< 0.7 vs ≥ 0.7 mg/kg/day, respectively). AEs occurred in 20% of the patients in the low-dose MMI group, and in 50% patients in the high-dose MMI group (p = 0.031). A greater variety of AEs was observed in the high-dose group. Neutropenia and rash were observed in both groups. With treatment transition to low-dose MMI according to the Japanese Society for Pediatric Endocrinology guidelines, we expect a decrease in the incidence of AEs in future. However, we should be careful as neutropenia and rash can occur independently of the MMI dose. PMID:28203042

  18. Do Asian renal transplant patients need another mycophenolate mofetil dose compared with Caucasian or African American patients?

    PubMed

    Li, Pengmei; Shuker, Nauras; Hesselink, Dennis A; van Schaik, Ron H N; Zhang, Xianglin; van Gelder, Teun

    2014-10-01

    Mycophenolate mofetil (MMF) is used to prevent acute rejection following solid organ transplantation in transplant centers all over the world. Patients from different ethnic backgrounds are treated with this drug, for which therapeutic drug monitoring (TDM) has not become the standard of practice in most centers. Whether or not some ethnic groups require a different MMF dose has been a topic of debate in recent years. In this review, it is shown that Asian patients, compared with Caucasian patients, with a comparable MMF dose reach higher mycophenolic acid (MPA) exposure. Also clinical experience points toward more adverse events in case of treatment with 1 g MMF bid in Asian patients, and therefore, for this ethnic group, a lower maintenance dose seems justified. In contrast, African American patients reach similar drug concentrations as Caucasians patients receiving the same MMF dose, but due to immunological reasons, they require a higher MMF dose to reach comparable acute rejection incidences. When TDM is performed, clinicians can correct the dose and compensate for interethnic differences in drug exposure. Otherwise, it is important to choose the right dose. This optimal dose is 20-46% lower in Asian transplant recipients than in Caucasian or African American patients.

  19. Radiation dose to patient and personnel during extracorporeal shock wave lithotripsy

    SciTech Connect

    Bush, W.H.; Jones, D.; Gibbons, R.P.

    1987-10-01

    Radiation dose to the patient and personnel was determined during extracorporeal shock wave lithotripsy treatment of 60 patients. Surface radiation dose to the patient's back from the fluoroscopy unit on the side with the kidney stone averaged 10 rem (100 mSv.) per case, although the range was wide (1 to 30 rem). The surface dose from the opposing biplane x-ray unit was less, averaging 5.5 rem (55 mSv.) per case but again with a wide range (0.1 to 21 rem). Exit dose at the lower abdomen averaged 13 mrem. (0.13 mSv.) per case and estimated female gonad dose averaged 100 mrem. (1.2 mSv.). Radiation dose to personnel working in the extracorporeal shock wave lithotripsy suite averaged less than 2 mrem. (0.02 mSv.) per case, making it a procedure that is safe in regard to radiation exposure.

  20. Reducing Radiation Dose in Emergency CT Scans While Maintaining Equal Image Quality: Just a Promise or Reality for Severely Injured Patients?

    PubMed Central

    Lembcke, Alexander; Pöllinger, Alexander; Wieners, Gero; Renz, Diane; Streitparth, Florian

    2013-01-01

    Objective. This study aims to assess the impact of adaptive statistical iterative reconstruction (ASIR) on CT imaging quality, diagnostic interpretability, and radiation dose reduction for a proven CT acquisition protocol for total body trauma. Methods. 18 patients with multiple trauma (ISS ≥ 16) were examined either with a routine protocol (n = 6), 30% (n = 6), or 40% (n = 6) of iterative reconstruction (IR) modification in the raw data domain of the routine protocol (140 kV, collimation: 40, noise index: 15). Study groups were matched by scan range and maximal abdominal diameter. Image noise was quantitatively measured. Image contrast, image noise, and overall interpretability were evaluated by two experienced and blinded readers. The amount of radiation dose reductions was evaluated. Results. No statistically significant differences between routine and IR protocols regarding image noise, contrast, and interpretability were present. Mean effective dose for the routine protocol was 25.3 ± 2.9 mSv, 19.7 ± 5.8 mSv for the IR 30, and 17.5 ± 4.2 mSv for the IR 40 protocol, that is, 22.1% effective dose reduction for IR 30 (P = 0.093) and 30.8% effective dose reduction for IR 40 (P = 0.0203). Conclusions. IR does not reduce study interpretability in total body trauma protocols while providing a significant reduction in effective radiation dose. PMID:24381762

  1. Bortezomib cumulative dose, efficacy, and tolerability with three different bortezomib-melphalan-prednisone regimens in previously untreated myeloma patients ineligible for high-dose therapy

    PubMed Central

    Mateos, María-Victoria; Bringhen, Sara; Richardson, Paul G.; Lahuerta, Juan Jose; Larocca, Alessandra; Oriol, Albert; Boccadoro, Mario; García-Sanz, Ramón; Di Raimondo, Francesco; Esseltine, Dixie-Lee; van de Velde, Helgi; Desai, Avinash; Londhe, Anil; San Miguel, Jesús F.; Palumbo, Antonio

    2014-01-01

    Substantial efficacy has been demonstrated with bortezomib-melphalan-prednisone in phase III studies in transplant-ineligible myeloma patients using various twice-weekly and once-weekly bortezomib dosing schedules. In VISTA, the regimen comprised four 6-week twice-weekly cycles, plus five 6-week once-weekly cycles. In the GIMEMA MM-03-05 study, the bortezomib-melphalan-prednisone regimen was either per VISTA (‘GIMEMA twice-weekly’), or comprised nine 5-week once-weekly cycles (‘GIMEMA once-weekly’). In the GEM2005MAS65 study, the regimen comprised one 6-week twice-weekly cycle, plus five 5-week once-weekly cycles. We evaluated the cumulative bortezomib dose administered during bortezomib-melphalan-prednisone, as well as efficacy and tolerability, using patient-level study data. Over all bortezomib-melphalan-prednisone cycles (nine in VISTA/GIMEMA; six in GEM2005MAS65), the median cumulative bortezomib dose administered was 38.5, 42.1, 40.3, and 32.9 mg/m2 in VISTA, GIMEMA twice-weekly, GIMEMA once-weekly, and GEM2005MAS65, respectively, and the respective proportions of planned bortezomib dose actually delivered were 57.0%, 62.3%, 86.1%, and 90.4%. Response rates following bortezomib-melphalan-prednisone were 74–87% and appeared generally similar between studies. Three-year survival rates were 67.9–75.7% across studies. Grade 3/4 peripheral neuropathy rates were 13% in VISTA and 14% in GIMEMA twice-weekly, but were lower at 2% in GIMEMA once-weekly and 7% in GEM2005MAS65. Discontinuations and bortezomib dose reductions due to peripheral neuropathy were reduced in GIMEMA once-weekly versus VISTA and GIMEMA twice-weekly. Exclusive or predominant use of once-weekly bortezomib dosing in GIMEMA once-weekly and GEM2005MAS65 resulted in high efficacy, comparable with that demonstrated in VISTA, and similar cumulative bortezomib dose with reduced toxicity. Trials are registered with ClinicalTrials.gov: VISTA (Identifier:00111319), GIMEMA MM-03-05 (Identifier

  2. Reduction in retinal nerve fiber layer thickness in migraine patients.

    PubMed

    Gipponi, Stefano; Scaroni, Niccolò; Venturelli, Elisabetta; Forbice, Eliana; Rao, Renata; Liberini, Paolo; Padovani, Alessandro; Semeraro, Francesco

    2013-06-01

    confocal images. The statistical analysis has been performed using the Statistical Package for Social Sciences program. The Student's t test has been used to compare numeric variables between migraine and control groups. p value >0.05 has been considered not significant. We have analyzed 40 female subjects, 24 included in the study group and 16 included in the control group. Two migraine patients have been excluded. No differences have been found in the visual acuity between the two groups. Comparing RNFLs of a single eye per person in the two groups, we have found that migraine patients showed significant reduction in the superior quadrants (p < 0.005). Also evaluating both eyes per person there was a significant difference in the same quadrant between the two groups (p < 0.05). The result of this present study show that migraine patients have RNFL thickness reduction in the superior retinal quadrant compared with normal subjects. It is important to underline that RNFL thickness measurement could be a new interesting technique to evaluate the evolution of migraine and perhaps to study if prophylactic treatment could reduce retinal abnormalities seen in migraine patients. OCT-SD is a simple exam that could be repeated and then used for evaluation of headache progression during the time. Our study shows that RNFLs thickness does not depend on illness duration and frequency.

  3. The Effect of Patient Weight and Provider Training and Experience on Dosing of Rocuronium

    PubMed Central

    Rodriguez, L.; Banks, S.; Major, B. T.; Rodriguez, Y.

    2016-01-01

    Introduction. Maintenance dosing of neuromuscular blocking agents is complex and varies with patient, procedure, and clinical situation. With this in mind, we sought to identify factors impacting the maintenance dosing of neuromuscular blockers as a step toward identifying best practice with respect to minimizing residual neuromuscular blockade. Methods. Cases utilizing rocuronium from July 1, 2010, to June 30, 2014, at the sponsoring institution were analyzed. Using a mixed model to account for repeated measures, patients were analyzed by dose and weight category as defined by the World Health Organization (eight categories ranging from very severely underweight to very severely obese) as well as by the administering provider's level of experience. Results. The study included 12,671 patients with a mean age of 49.7 (SD 16.7). Increasing weight category and higher levels of provider experience were associated with higher doses for rocuronium. There were no differences in initial dose or in frequency of maintenance dosing by weight category after controlling for case length. Discussion. The two dosing patterns identified, higher doses for overweight patients and higher doses administered by experienced providers, are modifiable factors that could enhance patient safety. PMID:27429615

  4. Evaluation of administered dose using portal images in craniospinal irradiation of pediatric patients.

    PubMed

    Coelho, Carina Marques; Calçada, Raquel; Rodrigues, Sofia; Barragán, Juan Antonio; Sá, Ana Cravo; Macedo, Ana Paula; de Fátima Monsanto, Maria

    2017-03-21

    This study aimed to assess the administered dose based on portal imaging in craniospinal pediatric irradiation by evaluating cases in which portal images did or did not account for the total administered dose. We also intended to calculate the mean increase in total administered dose. Data were collected from General University Hospital Gregorio Marañón; we evaluated the total dose administered, total dose planned, number of portal images per treatment and corresponding monitor units of two different groups: one in which the dose from portal images is deducted from the total administered dose (D), and another in which it was not (N). We used descriptive statistics to analyze the collected data, including the mean and respective standard deviation. We used the Shapiro-Wilk and Spearman rank correlation coefficient tests and estimated the linear regression coefficients. Patients in group D received a mean dose of 29.00 ± 10.28 cGy based on the verification portal images, a quantity that was deducted from the planned dose to match the total administered dose. Patients in group N received a mean dose of 41.50 ± 30.53 cGy, which was not deducted from the planned dose, evidencing a mean increase of 41.50 ± 30.55 cGy over the total administered dose. The acquisition of the set-up verification portal images, without their inclusion in the total administered dose, reflects an average increase in total dose for craniospinal irradiation of pediatric patients. Subtraction of the monitor units used to acquire the verification images is recommended.

  5. Is patient size important in dose determination and optimization in cardiology?

    NASA Astrophysics Data System (ADS)

    Reay, J.; Chapple, C. L.; Kotre, C. J.

    2003-12-01

    Patient dose determination and optimization have become more topical in recent years with the implementation of the Medical Exposures Directive into national legislation, the Ionising Radiation (Medical Exposure) Regulations. This legislation incorporates a requirement for new equipment to provide a means of displaying a measure of patient exposure and introduces the concept of diagnostic reference levels. It is normally assumed that patient dose is governed largely by patient size; however, in cardiology, where procedures are often very complex, the significance of patient size is less well understood. This study considers over 9000 cardiology procedures, undertaken throughout the north of England, and investigates the relationship between patient size and dose. It uses simple linear regression to calculate both correlation coefficients and significance levels for data sorted by both room and individual clinician for the four most common examinations, left ventrical and/or coronary angiography, single vessel stent insertion and single vessel angioplasty. This paper concludes that the correlation between patient size and dose is weak for the procedures considered. It also illustrates the use of an existing method for removing the effect of patient size from dose survey data. This allows typical doses and, therefore, reference levels to be defined for the purposes of dose optimization.

  6. A simplified method of four-dimensional dose accumulation using the mean patient density representation

    SciTech Connect

    Glide-Hurst, Carri K.; Hugo, Geoffrey D.; Liang Jian; Yan Di

    2008-12-15

    The purpose of this work was to demonstrate, both in phantom and patient, the feasibility of using an average 4DCT image set (AVG-CT) for 4D cumulative dose estimation. A series of 4DCT numerical phantoms and corresponding AVG-CTs were generated. For full 4D dose summation, static dose was calculated on each phase and cumulative dose was determined by combining each phase's static dose distribution with known tumor displacement. The AVG-CT cumulative dose was calculated similarly, although the same AVG-CT static dose distribution was used for all phases (i.e., tumor displacements). Four lung cancer cases were also evaluated for stereotactic body radiotherapy and conformal treatments; however, deformable image registration of the 4DCTs was used to generate the displacement vector fields (DVFs) describing patient-specific motion. Dose discrepancy between full 4D summation and AVG-CT approach was calculated and compared. For all phantoms, AVG-CT approximation yielded slightly higher cumulative doses compared to full 4D summation, with dose discrepancy increasing with increased tumor excursion. In vivo, using the AVG-CT coupled with deformable registration yielded clinically insignificant differences for all GTV parameters including the minimum, mean, maximum, dose to 99% of target, and dose to 1% of target. Furthermore, analysis of the spinal cord, esophagus, and heart revealed negligible differences in major dosimetric indices and dose coverage between the two dose calculation techniques. Simplifying 4D dose accumulation via the AVG-CT, while fully accounting for tumor deformation due to respiratory motion, has been validated, thereby, introducing the potential to streamline the use of 4D dose calculations in clinical practice, particularly for adaptive planning purposes.

  7. Application of EPR dosimetry in bone for ex vivo measurements of doses in radiotherapy patients.

    PubMed

    Krefft, K; Drogoszewska, B; Kaminska, J; Juniewicz, M; Wołąkiewicz, G; Jakacka, I; Ciesielski, B

    2014-11-01

    In the present study, bone samples from three patients treated in radiotherapy facilities in Poland were used for the determination of doses absorbed during radiotherapy. The samples were obtained during surgical treatments of patients performed due to medical indications. For the purpose of retrospective dosimetry, sensitivity of the radiation-induced EPR signal was individually calibrated in the samples by re-irradiation of the samples with known doses. The doses reconstructed in bones extracted within 6 months after irradiation were consistent with those calculated by treatment planning systems. The dose reconstructed in the bone removed 6 y after radiotherapy was ∼14% lower than the calculated one.

  8. Analysis and reduction of thermal dose errors in MRgFUS treatment.

    PubMed

    Zucconi, Fabio; Colombo, Paola E; Pasetto, Stefano; Lascialfari, Alessandro; Ticca, Cristiana; Torresin, Alberto

    2014-02-01

    ExAblate 2000 MRgFUS system (InSightec) installed in Ospedale Maggiore Niguarda Ca' Granda (Milano, Italy) is currently used to treat uterine fibroids. Through the magnetic resonance thermometry (PRF method), it is possible to monitor the temperature in the target in real-time and compute the treated region calculating the thermal dose. The purpose of this work is to investigate the errors in the temperature measurements and their effect on thermal dose. A low pass filtering of temperature maps is proposed to reduce the errors and therefore to improve the reliability of the treated regions calculated. The PRF method was studied through a calibration experiment on ex vivo pig muscle. The outcome resulted to be a very good linearity (p value 0.03) between phase and temperature in the range of interest, and an α value of -0.0109 ± 0.0002 ppm/°C. Temperature statistical uncertainty was evaluated by analyzing the temperature readout variability in specific gel provided by InSightec for daily quality assurance control. It resulted to be 1.89 ± 0.32 °C. A Monte Carlo simulation of the MRI temperature measurement and thermal dose calculations in our specific conditions of geometry and statistical uncertainty revealed that a low-pass filtering process on each temperature map can strongly reduce systematic errors in thermal dose evaluations (1.11 overestimation factor instead of 2.62 without filter); consequently the systematic errors on the size of the predicted ablated area are reduced as well.

  9. Occupational dose reduction at Department of Energy contractor facilities: Study of ALARA programs. Status 1990

    SciTech Connect

    Dionne, B.J.; Meinhold, C.B.; Khan, T.A.; Baum, J.W.

    1992-08-01

    This report provides the US Department of Energy (DOE) and its contractors with information that will be useful for reducing occupational radiation doses at DOE`s nuclear facilities. In 1989 and 1990, health physicists from the Brookhaven National Laboratory`s (BNL) ALARA Center visited twelve DOE contractor facilities with annual collective dose equivalents greater than 100 person-rem (100 person-cSv). The health physicists interviewed radiological safety staff, engineers, and training personnel who were responsible for dose control. The status of ALARA practices at the major contractor facilities was compared with the requirements and recommendation in DOE Order 5480.11 ``Radiation Protection for Occupational Workers`` and PNL-6577 ``Health Physics Manual of Good Practices for Reducing Radiation Exposure to Levels that are as Low as Reasonably Achievable.`` The information and data collected are described and examples of successful practices are presented. The findings on the status of the DOE Contractor ALARA Programs are summarized and evaluated. In addition, the supplement to this report contains examples of good-practice documents associated with implementing the major elements of a formally documented ALARA program for a major DOE contractor facility.

  10. Patient-specific dose estimation for pediatric abdomen-pelvis CT

    NASA Astrophysics Data System (ADS)

    Li, Xiang; Samei, Ehsan; Segars, W. Paul; Sturgeon, Gregory M.; Colsher, James G.; Frush, Donald P.

    2009-02-01

    The purpose of this study is to develop a method for estimating patient-specific dose from abdomen-pelvis CT examinations and to investigate dose variation across patients in the same weight group. Our study consisted of seven pediatric patients in the same weight/protocol group, for whom full-body computer models were previously created based on the patients' CT data obtained for clinical indications. Organ and effective dose of these patients from an abdomen-pelvis scan protocol (LightSpeed VCT scanner, 120-kVp, 85-90 mA, 0.4-s gantry rotation period, 1.375-pitch, 40-mm beam collimation, and small body scan field-of-view) was calculated using a Monte Carlo program previously developed and validated for the same CT system. The seven patients had effective dose of 2.4-2.8 mSv, corresponding to normalized effective dose of 6.6-8.3 mSv/100mAs (coefficient of variation: 7.6%). Dose variations across the patients were small for large organs in the scan coverage (mean: 6.6%; range: 4.9%-9.2%), larger for small organs in the scan coverage (mean: 10.3%; range: 1.4%-15.6%), and the largest for organs partially or completely outside the scan coverage (mean: 14.8%; range: 5.7%-27.7%). Normalized effective dose correlated strongly with body weight (correlation coefficient: r = -0.94). Normalized dose to the kidney and the adrenal gland correlated strongly with mid-liver equivalent diameter (kidney: r = -0.97; adrenal glands: r = -0.98). Normalized dose to the small intestine correlated strongly with mid-intestine equivalent diameter (r = -0.97). These strong correlations suggest that patient-specific dose may be estimated for any other child in the same size group who undergoes the abdomen-pelvis scan.

  11. Is there a difference between levodopa/ dopa-decarboxylase inhibitor and entacapone and levodopa/dopa-decarboxylase inhibitor dose fractionation strategies in Parkinson's disease patients experiencing symptom re-emergence due to wearing-off? The Honeymoon Study.

    PubMed

    Destée, Alain; Rérat, Karin; Bourdeix, Isabelle

    2009-01-01

    Two strategies to manage symptom re-emergence due to wearing-off with conventional levodopa/dopa-decarboxylase inhibitor (DDCI) therapy were compared in patients with Parkinson's disease (PD) in this randomized, open-label trial. PD patients receiving 3 daily doses of levodopa/DDCI were randomized to either levodopa/DDCI and entacapone or an increased dose frequency of levodopa/DDCI with or without an increased total daily dose (dose fractionation). After 1 month of treatment, patients were followed up for 1 year. A greater proportion of levodopa/DDCI and entacapone-treated patients had treatment success compared with dose-fractionated patients, according to investigator Clinical Global Impression of Change scores at 1 month (68 vs. 59%, respectively) and 1 year (60 vs. 51%, respectively). Mean 'off' time (time with symptoms) was improved in both groups at 1 month and 1 year, despite a reduction in the mean daily levodopa dose in the levodopa/DDCI and entacapone group at 1 month. The mean daily levodopa dose was increased in the dose fractionation group. At 1 month, there was a 4% reduction in patients experiencing dyskinesia with levodopa/DDCI and entacapone and a 3% increase with dose fractionation. These data suggest that levodopa/DDCI and entacapone reduces time with symptoms, the rate of motor complications and the daily levodopa dose compared with dose fractionation. However, as the observed differences were not statistically significant, further studies are required to confirm these results.

  12. Occupational dose reduction at Department of Energy contractor facilities: Bibliography of selected readings in radiation protection and ALARA; Volume 5

    SciTech Connect

    Dionne, B.J.; Sullivan, S.G.; Baum, J.W.

    1994-01-01

    Promoting the exchange of information related to implementation of the As Low as Reasonably Achievable (ALARA) philosophy is a continuing objective for the Department of Energy (DOE). This report was prepared by the Brookhaven National Laboratory (BNL) ALARA Center for the DOE Office of Health. It contains the fifth in a series of bibliographies on dose reduction at DOE facilities. The BNL ALARA Center was originally established in 1983 under the sponsorship of the Nuclear Regulatory Commission to monitor dose-reduction research and ALARA activities at nuclear power plants. This effort was expanded in 1988 by the DOE`s Office of Environment, Safety and Health, to include DOE nuclear facilities. This bibliography contains abstracts relating to various aspects of ALARA program implementation and dose-reduction activities, with a specific focus on DOE facilities. Abstracts included in this bibliography were selected from proceedings of technical meetings, journals, research reports, searches of the DOE Energy, Science and Technology Database (in general, the citation and abstract information is presented as obtained from this database), and reprints of published articles provided by the authors. Facility types and activities covered in the scope of this report include: radioactive waste, uranium enrichment, fuel fabrication, spent fuel storage and reprocessing, facility decommissioning, hot laboratories, tritium production, research, test and production reactors, weapons fabrication and testing, fusion, uranium and plutonium processing, radiography, and accelerators. Information on improved shielding design, decontamination, containments, robotics, source prevention and control, job planning, improved operational and design techniques, as well as on other topics, has been included. In addition, DOE/EH reports not included in previous volumes of the bibliography are in this volume (abstracts 611 to 684). This volume (Volume 5 of the series) contains 217 abstracts.

  13. Influence of thyroid volume reduction on absorbed dose in 131I therapy studied by using Geant4 Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Ziaur, Rahman; Sikander, M. Mirza; Waheed, Arshed; Nasir, M. Mirza; Waheed, Ahmed

    2014-05-01

    A simulation study has been performed to quantify the effect of volume reduction on the thyroid absorbed dose per decay and to investigate the variation of energy deposition per decay due to β- and γ-activity of 131I with volume/mass of thyroid, for water, ICRP- and ICRU-soft tissue taken as thyroid material. A Monte Carlo model of the thyroid, in the Geant4 radiation transport simulation toolkit was constructed to compute the β- and γ-absorbed dose in the simulated thyroid phantom for various values of its volume. The effect of the size and shape of the thyroid on energy deposition per decay has also been studied by using spherical, ellipsoidal and cylindrical models for the thyroid and varying its volume in 1-25 cm3 range. The relative differences of Geant4 results for different models with each other and MCNP results lie well below 1.870%. The maximum relative difference among the Geant4 estimated results for water with ICRP and ICRU soft tissues is not more than 0.225%. S-values for ellipsoidal, spherical and cylindrical thyroid models were estimated and the relative difference with published results lies within 3.095%. The absorbed fraction values for beta particles show a good agreement with published values within 2.105% deviation. The Geant4 based simulation results of absorbed fractions for gammas again show a good agreement with the corresponding MCNP and EGS4 results (±6.667%) but have 29.032% higher values than that of MIRD calculated values. Consistent with previous studies, the reduction of the thyroid volume is found to have a substantial effect on the absorbed dose. Geant4 simulations confirm dose dependence on the volume/mass of thyroid in agreement with MCNP and EGS4 computed values but are substantially different from MIRD8 data. Therefore, inclusion of size/mass dependence is indicated for 131I radiotherapy of the thyroid.

  14. High-dose nimotuzumab improves the survival rate of esophageal cancer patients who underwent radiotherapy

    PubMed Central

    Wang, Chunyu; Fu, Xiaolong; Cai, Xuwei; Wu, Xianghua; Hu, Xichun; Fan, Min; Xiang, Jiaqing; Zhang, Yawei; Chen, Haiquan; Jiang, Guoliang; Zhao, Kuaile

    2016-01-01

    Nimotuzumab (h-R3) is a humanized monoclonal antibody that is safe to use against epidermal growth factor receptor (EGFR). However, the available information is insufficient about the dose effect of monoclonal antibody against epidermal growth factor receptor for the treatment of esophageal squamous cell carcinoma (ESCC). We retrospectively recruited 66 patients with ESCC who were treated with h-R3 and chemoradiotherapy/radiotherapy. Patients who received more than 1,200 mg of h-R3 were classified as the high-dose group, and the remaining patients were classified as the low-dose group. The endpoint for efficacy was the overall survival. Differences in survival between the groups were analyzed using the log-rank test. The Cox proportional hazards model was used in multivariate analysis to identify independent prognostic factors. The low-dose and high-dose groups comprised 55 and eleven patients, respectively. The median follow-up time in the final analysis was 46 months. The high-dose group showed no increased incidence of toxicities compared to the low-dose group. The 1-, 2-, and 5-year overall survival rates in the low-dose and high-dose groups were 66.9%, 50.0%, 31.5% and 90.0%, 80.0%, 66.7%, respectively (P=0.04). Multivariate analyses showed that the high-dose group had better survival than the low-dose group (hazard ratio 0.28, 95% confidence interval 0.09–0.94, P=0.039). Taken together, high-dose h-R3 showed limited toxicity and improved survival in patients with ESCC. PMID:26766917

  15. Evaluation of patient effective doses in CT urography, intravenous urography and renal scintigraphy.

    PubMed

    Hamza, Y; Sulieman, A; Abuderman, A; Alzimami, K; Omer, H

    2015-07-01

    Imaging of the renal system is performed with different techniques depending mainly on clinical symptoms and signs. This study intended to evaluate patient effective doses undergoing renal scintigraphy (technetium-99m-diethylene-triamine-pentaacetic acid), computed tomography urography (CTU) and intravenous urography (IVU). A total of 60 patients were evaluated using Orbiter 37 Gamma camera single head, dual-slice CT scanner and conventional X-ray machine with computed radiography (CR) processing unit. Patients effective dose were estimated using the administered activity, DosCal software and dose length product value for renal scan, IVU and CTU procedures, respectively. Patients' effective doses during renal scan, CTU and IVU procedures were 0.78 ± 0.18, 2.53 ± 0.94 and 1.81 ± 0.20 mSv, in that order. Patients were exposed to a higher effective dose during CTU compared with other two procedures. Patient doses depend on the size of patient, the type of scanner and the imaging protocol used. Effective doses considered low compared with previous studies.

  16. Comparison of patient specific dose metrics between chest radiography, tomosynthesis, and CT for adult patients of wide ranging body habitus

    SciTech Connect

    Zhang, Yakun; Li, Xiang; Segars, W. Paul; Samei, Ehsan

    2014-02-15

    Purpose: Given the radiation concerns inherent to the x-ray modalities, accurately estimating the radiation doses that patients receive during different imaging modalities is crucial. This study estimated organ doses, effective doses, and risk indices for the three clinical chest x-ray imaging techniques (chest radiography, tomosynthesis, and CT) using 59 anatomically variable voxelized phantoms and Monte Carlo simulation methods. Methods: A total of 59 computational anthropomorphic male and female extended cardiac-torso (XCAT) adult phantoms were used in this study. Organ doses and effective doses were estimated for a clinical radiography system with the capability of conducting chest radiography and tomosynthesis (Definium 8000, VolumeRAD, GE Healthcare) and a clinical CT system (LightSpeed VCT, GE Healthcare). A Monte Carlo dose simulation program (PENELOPE, version 2006, Universitat de Barcelona, Spain) was used to mimic these two clinical systems. The Duke University (Durham, NC) technique charts were used to determine the clinical techniques for the radiographic modalities. An exponential relationship between CTDI{sub vol} and patient diameter was used to determine the absolute dose values for CT. The simulations of the two clinical systems compute organ and tissue doses, which were then used to calculate effective dose and risk index. The calculation of the two dose metrics used the tissue weighting factors from ICRP Publication 103 and BEIR VII report. Results: The average effective dose of the chest posteroanterior examination was found to be 0.04 mSv, which was 1.3% that of the chest CT examination. The average effective dose of the chest tomosynthesis examination was found to be about ten times that of the chest posteroanterior examination and about 12% that of the chest CT examination. With increasing patient average chest diameter, both the effective dose and risk index for CT increased considerably in an exponential fashion, while these two dose

  17. Radiation Exposure During Uterine Artery Embolization: Effective Measures to Minimize Dose to the Patient

    SciTech Connect

    Scheurig-Muenkler, Christian; Powerski, Maciej J.; Mueller, Johann-Christoph; Kroencke, Thomas J.

    2015-06-15

    PurposeEvaluation of patient radiation exposure during uterine artery embolization (UAE) and literature review to identify techniques minimizing required dose.MethodsA total of 224 of all included 286 (78 %) women underwent UAE according to a standard UAE-protocol (bilateral UAE from unilateral approach using a Rösch inferior mesenteric and a microcatheter, no aortography, no ovarian artery catheterization or embolization) and were analyzed for radiation exposure. Treatment was performed on three different generations of angiography systems: (I) new generation flat-panel detector (N = 108/151); (II) classical image amplifier and pulsed fluoroscopy (N = 79/98); (III) classical image amplifier and continuous fluoroscopy (N = 37/37). Fluoroscopy time (FT) and dose-area product (DAP) were documented. Whenever possible, the following dose-saving measures were applied: optimized source-object, source-image, and object-image distances, pulsed fluoroscopy, angiographic runs in posterior-anterior direction with 0.5 frames per second, no magnification, tight collimation, no additional aortography.ResultsIn a standard bilateral UAE, the use of the new generation flat-panel detector in group I led to a significantly lower DAP of 3,156 cGy × cm{sup 2} (544–45,980) compared with 4,000 cGy × cm{sup 2} (1,400–13,000) in group II (P = 0.033). Both doses were significantly lower than those of group III with 8,547 cGy × cm{sup 2} (3,324–35,729; P < 0.001). Other reasons for dose escalation were longer FT due to difficult anatomy or a large leiomyoma load, additional angiographic runs, supplementary ovarian artery embolization, and obesity.ConclusionsThe use of modern angiographic units with flat panel detectors and strict application of methods of radiation reduction lead to a significantly lower radiation exposure. Target DAP for UAE should be kept below 5,000 cGy × cm{sup 2}.

  18. Computed tomography pulmonary angiography using a 20% reduction in contrast medium dose delivered in a multiphasic injection

    PubMed Central

    Chen, Mitchell; Mattar, Gaith; Abdulkarim, Jamal A

    2017-01-01

    AIM To evaluate the feasibility of reducing the dose of iodinated contrast agent in computed tomography pulmonary angiography (CTPA). METHODS One hundred and twenty-seven patients clinically suspected of having pulmonary embolism underwent spiral CTPA, out of whom fifty-seven received 75 mL and the remaining seventy a lower dose of 60 mL of contrast agent. Both doses were administered in a multiphasic injection. A minimum opacification threshold of 250 Hounsfield units (HU) in the main pulmonary artery is used for assessing the technical adequacy of the scans. RESULTS Mean opacification was found to be positively correlated to patient age (Pearson’s correlation 0.4255, P < 0.0001) and independent of gender (male:female, 425.6 vs 450.4, P = 0.34). When age is accounted for, the study and control groups did not differ significantly in their mean opacification in the main (436.8 vs 437.9, P = 0.48), left (416.6 vs 419.8, P = 0.45) or the right pulmonary arteries (417.3 vs 423.5, P = 0.40). The number of sub-optimally opacified scans (the mean opacification in the main pulmonary artery < 250 HU) did not differ significantly between the study and control groups (7 vs 10). CONCLUSION A lower dose of iodine contrast at 60 mL can be feasibly used in CTPA without resulting in a higher number of sub-optimally opacified scans.

  19. Voxel-based dose prediction with multi-patient atlas selection for automated radiotherapy treatment planning

    NASA Astrophysics Data System (ADS)

    McIntosh, Chris; Purdie, Thomas G.

    2017-01-01

    Automating the radiotherapy treatment planning process is a technically challenging problem. The majority of automated approaches have focused on customizing and inferring dose volume objectives to be used in plan optimization. In this work we outline a multi-patient atlas-based dose prediction approach that learns to predict the dose-per-voxel for a novel patient directly from the computed tomography planning scan without the requirement of specifying any objectives. Our method learns to automatically select the most effective atlases for a novel patient, and then map the dose from those atlases onto the novel patient. We extend our previous work to include a conditional random field for the optimization of a joint distribution prior that matches the complementary goals of an accurately spatially distributed dose distribution while still adhering to the desired dose volume histograms. The resulting distribution can then be used for inverse-planning with a new spatial dose objective, or to create typical dose volume objectives for the canonical optimization pipeline. We investigated six treatment sites (633 patients for training and 113 patients for testing) and evaluated the mean absolute difference in all DVHs for the clinical and predicted dose distribution. The results on average are favorable in comparison to our previous approach (1.91 versus 2.57). Comparing our method with and without atlas-selection further validates that atlas-selection improved dose prediction on average in whole breast (0.64 versus 1.59), prostate (2.13 versus 4.07), and rectum (1.46 versus 3.29) while it is less important in breast cavity (0.79 versus 0.92) and lung (1.33 versus 1.27) for which there is high conformity and minimal dose shaping. In CNS brain, atlas-selection has the potential to be impactful (3.65 versus 5.09), but selecting the ideal atlas is the most challenging.

  20. Correlation between scatter radiation dose at height of operator's eye and dose to patient for different angiographic projections.

    PubMed

    Leyton, Fernando; Nogueira, Maria S; Gubolino, Luiz A; Pivetta, Makyson R; Ubeda, Carlos

    2016-11-01

    Studies have reported cases of radiation-induced cataract among cardiology professionals. In view of the evidence of epidemiological studies, the ICRP recommends a new threshold for opacities and a new radiation dose to eye lens limit of 20mSv per year for occupational exposure. The aim of this paper is to report scattered radiation doses at the height of the operator's eye in an interventional cardiology facility without considering radiation protection devices and to correlate these values with different angiographic projections and operational modes. Measurements were taken in a cardiac laboratory with an angiography X-ray system equipped with flat-panel detector. PMMA plates of 30×30×5cm were used with a thickness of 20cm. Measurements were taken in two fluoroscopy modes (low and normal, 15pulses/s) and in cine mode (15frames/s). Four angiographic projections were used: anterior posterior; lateral; left anterior oblique caudal (spider); and left anterior oblique cranial, with a cardiac protocol for patients weighing between 70 and 90kg. Measurements of phantom entrance dose rate and scatter dose rate were performed with two Unfors Xi plus detectors. The detector measuring scatter radiation was positioned at the usual distance of the cardiologist's eyes during working conditions. There is a good linear correlation between the kerma area product and scatter dose at the lens. Experimental correlation factors of 2.3, 12.0, 12.2 and 17.6μSv/Gycm2 were found for different projections. PMMA entrance dose rates for low and medium fluoroscopy and cine modes were 13, 39 and 282mGy/min, respectively, for AP projection.

  1. Automatic patient dose registry and clinical audit on line for mammography.

    PubMed

    Ten, J I; Vano, E; Sánchez, R; Fernandez-Soto, J M

    2015-07-01

    The use of automatic registry systems for patient dose in digital mammography allows clinical audit and patient dose analysis of the whole sample of individual mammography exposures while fulfilling the requirements of the European Directives and other international recommendations. Further parameters associated with radiation exposure (tube voltage, X-ray tube output and HVL values for different kVp and target/filter combinations, breast compression, etc.) should be periodically verified and used to evaluate patient doses. This study presents an experience in routine clinical practice for mammography using automatic systems.

  2. Ezetimibe for the treatment of uncontrolled hypercholesterolemia in patients with high-dose statin therapy after renal transplantation.

    PubMed

    Kohnle, M; Pietruck, F; Kribben, A; Philipp, Th; Heemann, U; Witzke, O

    2006-01-01

    We investigated prospectively the efficacy of ezetimibe in addition to statin therapy in stable renal transplant patients in whom hypercholesterolemia was not sufficiently treated. Eighteen renal transplant patients received 10 mg ezetimibe once daily in addition to high-dose statin therapy for uncontrolled hypercholesterolemia. Total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides, Tacrolimus (Tac)- and Cyclosporine A (CsA) blood levels, creatinine, urea, liver enzymes, electrolytes and creatinkinase (CK) were measured before initiation of ezetimibe therapy, after 7 days, 6 weeks and 3 months. Cholesterol concentrations decreased significantly (p < 0.005) from 264 +/- 46 mg/dL at baseline to 205 +/- 48 mg/dL after 1 week to 202 +/- 48 mg/dL after 6 weeks and 212 +/- 40 mg/dL after 3 months (reduction after 3 months 21 +/- 10%). LDL-concentrations decreased significantly (p < 0.005) from 178 +/- 41 mg/dL at baseline to 129 +/- 35 mg/dL after 1 week to 123 +/- 25 after 6 weeks and to 117 +/- 40 mg/dL after 3 months (reduction after 3 months 37 +/- 14%). Two patients stopped ezetimibe therapy due to nausea and muscle pain without CK elevation. Significant changes of CsA and Tac blood levels, liver and muscle enzymes were not observed. Ezetimibe seems to be an effective therapy for uncontrolled hypercholesterolemia in renal transplant patients when combined with high-dose statin therapy.

  3. Optimal initial dose of oral cyclosporine in relation to its toxicities for graft-versus-host disease prophylaxis following reduced-intensity stem cell transplantation in Japanese patients.

    PubMed

    Kishi, Y; Murashige, N; Kami, M; Miyakoshi, S; Shibagaki, Y; Hamaki, T; Takaue, Y; Taniguchi, S

    2005-06-01

    Since the introduction of reduced-intensity stem-cell transplantation (RIST), allogeneic stem-cell transplantation has become available for elderly patients. While pharmacokinetics of cyclosporine might differ according to age or other factors, cyclosporine is uniformly started at an oral dose of 6 mg/kg/day. We retrospectively reviewed medical records of 35 patients aged between 32 and 65 (median 52) years who had undergone RIST. Doses of cyclosporine were adjusted to the target blood trough level of 150-250 ng/ml. Cyclosporine dosages were changed in 33 patients (94%). Dose reduction was required in 32 patients because of high blood levels (n=25), renal dysfunction (n=3), hepatic dysfunction (n=2), and hypertension (n=2). Cyclosporine doses were increased in one because of the suboptimal level. The median of the achieved stable doses was 3.1 mg/kg/day (range, 1.0-7.4). Five patients sustained Grade III toxicities according to NCI-CTC version 2.0: renal dysfunction (n=4), hyperbilirubinemia (n=2), and hypertension (n=2). No patients developed grade IV toxicity. There was no statistically significant difference in the frequency and severity of cyclosporine toxicities between patients aged 50 years and above and those below 50 years. The initial oral cyclosporine dose of 6 mg/kg/day was unnecessarily high irrespective of age. The possible overdose of cyclosporine might have aggravated regimen-related toxicities.

  4. Dose delivered from Varian's CBCT to patients receiving IMRT for prostate cancer

    NASA Astrophysics Data System (ADS)

    Wen, Ning; Guan, Huaiqun; Hammoud, Rabih; Pradhan, Deepak; Nurushev, T.; Li, Shidong; Movsas, Benjamin

    2007-04-01

    With the increased use of cone beam CT (CBCT) for daily patient setup, the accumulated dose from CBCT may be significantly higher than that from simulation CT or portal imaging. The objective of this work is to measure the dose from daily pelvic scans with fixed technical settings and collimations. CBCT scans were acquired in half-fan mode using a half bowtie and x-rays were delivered in pulsed-fluoro mode. The skin doses for seven prostate patients were measured on an IRB-approved protocol. TLD capsules were placed on the patient's skin at the central axis of three beams: AP, left lateral (Lt Lat) and right lateral (Rt Lat). To avoid the ring artefacts centred in the prostate, the treatment couch was dropped 3 cm from the patient's tattoo (central axis). The measured AP skin doses ranged 3-6 cGy for 20-33 cm separation. The larger the patient size the less the AP skin dose. Lateral doses did not change much with patient size. The Lt Lat dose was ~4.0 cGy, which was ~40% higher than the Rt Lat dose of ~2.6 cGy. To verify this dose asymmetry, surface doses on an IMRT QA phantom (oval shaped, 30 cm × 20 cm) were measured at the same three sites using TLD capsules with 3 cm table-drop. The dose asymmetry was due to: (1) kV source rotation which always starts from the patient's Lt Lat and ends at Lt Lat. Gantry rotation gets much slower near the end of rotation but dose rate stays constant and (2) 370° scan rotation (10° scan overlap on the Lt Lat side). In vivo doses were measured inside a Rando pelvic heterogeneous phantom using TLDs. The left hip (femoral head and neck) received the highest doses of ~10-11 cGy while the right hip received ~6-7 cGy. The surface and in vivo doses were also measured for phantoms at the central-axis setup. The difference was less than ~12% to the table-drop setup.

  5. Actual Dose Variation of Parotid Glands and Spinal Cord for Nasopharyngeal Cancer Patients During Radiotherapy

    SciTech Connect

    Han Chunhui Chen Yijen; Liu An; Schultheiss, Timothy E.; Wong, Jeffrey Y.C.

    2008-03-15

    Purpose: For intensity-modulated radiotherapy of nasopharyngeal cancer, accurate dose delivery is crucial to the success of treatment. This study aimed to evaluate the significance of daily image-guided patient setup corrections and to quantify the parotid gland volume and dose variations for nasopharyngeal cancer patients using helical tomotherapy megavoltage computed tomography (CT). Methods and Materials: Five nasopharyngeal cancer patients who underwent helical tomotherapy were selected retrospectively. Each patient had received 70 Gy in 35 fractions. Daily megavoltage CT scans were registered with the planning CT images to correct the patient setup errors. Contours of the spinal cord and parotid glands were drawn on the megavoltage CT images at fixed treatment intervals. The actual doses delivered to the critical structures were calculated using the helical tomotherapy Planned Adaptive application. Results: The maximal dose to the spinal cord showed a significant increase and greater variation without daily setup corrections. The significant decrease in the parotid gland volume led to a greater median dose in the later phase of treatment. The average parotid gland volume had decreased from 20.5 to 13.2 cm{sup 3} by the end of treatment. On average, the median dose to the parotid glands was 83 cGy and 145 cGy for the first and the last treatment fractions, respectively. Conclusions: Daily image-guided setup corrections can eliminate significant dose variations to critical structures. Constant monitoring of patient anatomic changes and selective replanning should be used during radiotherapy to avoid critical structure complications.

  6. A survey of patient doses from conventional diagnostic radiology examinations: first results from Serbia and Montenegro.

    PubMed

    Ciraj, Olivera; Kosutic, Dusko; Kovacevic, Milojko; Markovic, Srpko

    Diagnostic reference levels provide framework to reduce variability. The aim of this study is to establish, for the first time, a baseline for national diagnostic reference levels in Serbia and Montenegro for the most common X-ray examination types. Measurements of patient dose using kerma-area product meter and entrance surface air kerma assessment were performed on at least ten patients for each examination type, in each of 16 randomly selected hospitals in Serbia and Montenegro, so that a total of 3,026 procedures for nine different examination categories were included in the survey. Exposure settings and individual data were recorded for each patient. Mean, median and third quartile values of patient doses are reported. Results have shown wide variation of mean hospital doses, with factor of four for barium enema to 23 for thoracic spine radiography. Entrance surface air kerma were compared with previously published diagnostic reference levels (DRL) proposed by Commission of European Communities (CEC). Doses for all studied examination types except chest radiography were within European DRL. The reasons for dose variation are discussed. Survey data are aimed to help in development of an on-going national quality assurance and quality control programme in diagnostic radiology. The findings emphasize the importance of regular patient dose measurement to ensure that patient doses are kept as low as reasonable achievable.

  7. An open-label, multi-dose efficacy and safety study of intramuscular tetrodotoxin in patients with severe cancer-related pain.

    PubMed

    Hagen, Neil A; Fisher, Kim M; Lapointe, Bernard; du Souich, Patrick; Chary, Srini; Moulin, Dwight; Sellers, Ed; Ngoc, Anh Ho

    2007-08-01

    Cancer pain is a prevalent and serious public health issue, and more effective treatments are needed. This study evaluates the analgesic activity of tetrodotoxin, a highly selective sodium channel blocker, in cancer pain. A Phase IIa, open-label, multicenter, dose-escalation study of intramuscular tetrodotoxin was conducted in patients with severe, unrelieved cancer pain. The study design called for six ascending dose levels of intramuscular tetrodotoxin, administered over a four-day treatment period in hospitalized patients, with six patients to be enrolled within each successive dose level. Twenty-four patients underwent 31 courses of treatment at doses ranging from 15 to 90 microg daily, administered in divided doses, over four days. Most patients described transient perioral tingling or other mild sensory phenomena within about an hour of each treatment. Nausea and other toxicities were generally mild, but two patients experienced a serious adverse event, truncal and gait ataxia, that resolved over days. Seventeen of 31 treatments resulted in clinically meaningful reductions in pain intensity, and relief of pain persisted for up to two weeks or longer. Two patients had opioids held due to narcosis concurrent with relief of pain. Somatic, visceral, or neuropathic pain could all respond, but it was not possible to predict which patients were more likely to have an analgesic effect. Tetrodotoxin was overall safe. It effectively relieved severe, treatment-resistant cancer pain in the majority of patients and often for prolonged periods after treatment. It may have a novel mechanism of analgesic effect. Further study is warranted.

  8. Four-dimensional dose distributions of step-and-shoot IMRT delivered with real-time tumor tracking for patients with irregular breathing: Constant dose rate vs dose rate regulation

    SciTech Connect

    Yang Xiaocheng; Han-Oh, Sarah; Gui Minzhi; Niu Ying; Yu, Cedric X.; Yi Byongyong

    2012-09-15

    slower than the planning day. In contrast, DRRT method showed less than 1% reduction in target dose and no noticeable change in OAR dose under the same breathing period irregularities. When {+-}20% variation of target motion amplitude was present as breathing irregularity, the two delivery methods show compatible plan quality if the dose distribution of CDRT delivery is renormalized. Conclusions: Delivery of 4D-IMRT treatment plans, stemmed from 3D step-and-shoot IMRT and preprogrammed using SAM algorithm, is simulated for two dynamic MLC-based real-time tumor tracking strategies: with and without dose-rate regulation. Comparison of cumulative dose distribution indicates that the preprogrammed 4D plan is more accurately and efficiently conformed using the DRRT strategy, as it compensates the interplay between patient breathing irregularity and tracking delivery without compromising the segment-weight modulation.

  9. Development of a radiopharmaceutical dose calculator for pediatric patients undergoing diagnostic nuclear medicine studies

    PubMed Central

    Pandey, Anil Kumar; Sharma, Sanjay Kumar; Sharma, Punit; Gupta, Priyanka; Kumar, Rakesh

    2013-01-01

    Objective: It is important to ensure that as low as reasonably achievable (ALARA) concept during the radiopharmaceutical (RPH) dose administration in pediatric patients. Several methods have been suggested over the years for the calculation of individualized RPH dose, sometimes requiring complex calculations and large variability exists for administered dose in children. The aim of the present study was to develop a software application that can calculate and store RPH dose along with patient record. Materials and Methods: We reviewed the literature to select the dose formula and used Microsoft Access (a software package) to develop this application. We used the Microsoft Excel to verify the accurate execution of the dose formula. The manual and computer time using this program required for calculating the RPH dose were compared. Results: The developed application calculates RPH dose for pediatric patients based on European Association of Nuclear Medicine dose card, weight based, body surface area based, Clark, Solomon Fried, Young and Webster's formula. It is password protected to prevent the accidental damage and stores the complete record of patients that can be exported to Excel sheet for further analysis. It reduces the burden of calculation and saves considerable time i.e., 2 min computer time as compared with 102 min (manual calculation with the calculator for all seven formulas for 25 patients). Conclusion: The software detailed above appears to be an easy and useful method for calculation of pediatric RPH dose in routine clinical practice. This software application will help in helping the user to routinely applied ALARA principle while pediatric dose administration. PMID:24163510

  10. Nurse exposure doses resulted from bone scintigraphy patient

    NASA Astrophysics Data System (ADS)

    Tunçman, Duygu; Kovan, Bilal; Poyraz, Leyla; ćapali, Veli; Demir, Bayram; Türkmen, Cüneyt

    2016-03-01

    Bone scintigraphy is used for displaying the radiologic undiagnosed bone lesions in nuclear medicine. It's general indications are researching bone metastases, detection of radiographically occult fractures, staging and follow-up in primary bone tumors, diagnosis of paget's disease, investigation of loosening and infection in orthopedic implants. It is applied with using 99mTc labeled radiopharmaceuticals (e.g 99m Tc MDP,99mTc HEDP and 99mTc HMDP). 20 -25 mCi IV radiotracer was injected into vein and radiotracer emits gamma radiation. Patient waits in isolated room for about 3 hours then a gamma camera scans radiation area and creates an image. When some patient's situation is not good, patients are hospitalized until the scanning because of patients' close contact care need. In this study, measurements were taken from ten patients using Geiger Muller counter. After these measurements, we calculated nurse's exposure radiations from patient's routine treatment, examination and emergency station.

  11. Patient dose considerations for routine megavoltage cone-beam CT imaging

    SciTech Connect

    Morin, Olivier; Gillis, Amy; Descovich, Martina; Chen, Josephine; Aubin, Michele; Aubry, Jean-Francois; Chen Hong; Gottschalk, Alexander R.; Xia Ping; Pouliot, Jean

    2007-05-15

    Megavoltage cone-beam CT (MVCBCT), the recent addition to the family of in-room CT imaging systems for image-guided radiation therapy (IGRT), uses a conventional treatment unit equipped with a flat panel detector to obtain a three-dimensional representation of the patient in treatment position. MVCBCT has been used for more than two years in our clinic for anatomy verification and to improve patient alignment prior to dose delivery. The objective of this research is to evaluate the image acquisition dose delivered to patients for MVCBCT and to develop a simple method to reduce the additional dose resulting from routine MVCBCT imaging. Conventional CT scans of phantoms and patients were imported into a commercial treatment planning system (TPS: Phillips, Pinnacle) and an arc treatment mimicking the MVCBCT acquisition process was generated to compute the delivered acquisition dose. To validate the dose obtained from the TPS, a simple water-equivalent cylindrical phantom with spaces for MOSFETs and an ion chamber was used to measure the MVCBCT image acquisition dose. Absolute dose distributions were obtained by simulating MVCBCTs of 9 and 5 monitor units (MU) on pelvis and head and neck patients, respectively. A compensation factor was introduced to generate composite plans of treatment and MVCBCT imaging dose. The article provides a simple equation to compute the compensation factor. The developed imaging compensation method was tested on routinely used clinical plans for prostate and head and neck patients. The quantitative comparison between the calculated dose by the TPS and measurement points on the cylindrical phantom were all within 3%. The dose percentage difference for the ion chamber placed in the center of the phantom was only 0.2%. For a typical MVCBCT, the dose delivered to patients forms a small anterior-posterior gradient ranging from 0.6 to 1.2 cGy per MVCBCT MU. MVCBCT acquisitions in the pelvis and head and neck areas deliver slightly more dose than

  12. Pediatric patient and staff dose measurements in barium meal fluoroscopic procedures

    NASA Astrophysics Data System (ADS)

    Filipov, D.; Schelin, H. R.; Denyak, V.; Paschuk, S. A.; Porto, L. E.; Ledesma, J. A.; Nascimento, E. X.; Legnani, A.; Andrade, M. E. A.; Khoury, H. J.

    2015-11-01

    This study investigates patient and staff dose measurements in pediatric barium meal series fluoroscopic procedures. It aims to analyze radiographic techniques, measure the air kerma-area product (PKA), and estimate the staff's eye lens, thyroid and hands equivalent doses. The procedures of 41 patients were studied, and PKA values were calculated using LiF:Mg,Ti thermoluminescent dosimeters (TLDs) positioned at the center of the patient's upper chest. Furthermore, LiF:Mg,Cu,P TLDs were used to estimate the equivalent doses. The results showed a discrepancy in the radiographic techniques when compared to the European Commission recommendations. Half of the results of the analyzed literature presented lower PKA and dose reference level values than the present study. The staff's equivalent doses strongly depends on the distance from the beam. A 55-cm distance can be considered satisfactory. However, a distance decrease of ~20% leads to, at least, two times higher equivalent doses. For eye lenses this dose is significantly greater than the annual limit set by the International Commission on Radiological Protection. In addition, the occupational doses were found to be much higher than in the literature. Changing the used radiographic techniques to the ones recommended by the European Communities, it is expected to achieve lower PKA values ​​and occupational doses.

  13. Reconstruction of organ dose for external radiotherapy patients in retrospective epidemiologic studies

    NASA Astrophysics Data System (ADS)

    Lee, Choonik; Jung, Jae Won; Pelletier, Christopher; Pyakuryal, Anil; Lamart, Stephanie; Kim, Jong Oh; Lee, Choonsik

    2015-03-01

    Organ dose estimation for retrospective epidemiological studies of late effects in radiotherapy patients involves two challenges: radiological images to represent patient anatomy are not usually available for patient cohorts who were treated years ago, and efficient dose reconstruction methods for large-scale patient cohorts are not well established. In the current study, we developed methods to reconstruct organ doses for radiotherapy patients by using a series of computational human phantoms coupled with a commercial treatment planning system (TPS) and a radiotherapy-dedicated Monte Carlo transport code, and performed illustrative dose calculations. First, we developed methods to convert the anatomy and organ contours of the pediatric and adult hybrid computational phantom series to Digital Imaging and Communications in Medicine (DICOM)-image and DICOM-structure files, respectively. The resulting DICOM files were imported to a commercial TPS for simulating radiotherapy and dose calculation for in-field organs. The conversion process was validated by comparing electron densities relative to water and organ volumes between the hybrid phantoms and the DICOM files imported in TPS, which showed agreements within 0.1 and 2%, respectively. Second, we developed a procedure to transfer DICOM-RT files generated from the TPS directly to a Monte Carlo transport code, x-ray Voxel Monte Carlo (XVMC) for more accurate dose calculations. Third, to illustrate the performance of the established methods, we simulated a whole brain treatment for the 10 year-old male phantom and a prostate treatment for the adult male phantom. Radiation doses to selected organs were calculated using the TPS and XVMC, and compared to each other. Organ average doses from the two methods matched within 7%, whereas maximum and minimum point doses differed up to 45%. The dosimetry methods and procedures established in this study will be useful for the reconstruction of organ dose to support

  14. Reconstruction of organ dose for external radiotherapy patients in retrospective epidemiologic studies.

    PubMed

    Lee, Choonik; Jung, Jae Won; Pelletier, Christopher; Pyakuryal, Anil; Lamart, Stephanie; Kim, Jong Oh; Lee, Choonsik

    2015-03-21

    Organ dose estimation for retrospective epidemiological studies of late effects in radiotherapy patients involves two challenges: radiological images to represent patient anatomy are not usually available for patient cohorts who were treated years ago, and efficient dose reconstruction methods for large-scale patient cohorts are not well established. In the current study, we developed methods to reconstruct organ doses for radiotherapy patients by using a series of computational human phantoms coupled with a commercial treatment planning system (TPS) and a radiotherapy-dedicated Monte Carlo transport code, and performed illustrative dose calculations. First, we developed methods to convert the anatomy and organ contours of the pediatric and adult hybrid computational phantom series to Digital Imaging and Communications in Medicine (DICOM)-image and DICOM-structure files, respectively. The resulting DICOM files were imported to a commercial TPS for simulating radiotherapy and dose calculation for in-field organs. The conversion process was validated by comparing electron densities relative to water and organ volumes between the hybrid phantoms and the DICOM files imported in TPS, which showed agreements within 0.1 and 2%, respectively. Second, we developed a procedure to transfer DICOM-RT files generated from the TPS directly to a Monte Carlo transport code, x-ray Voxel Monte Carlo (XVMC) for more accurate dose calculations. Third, to illustrate the performance of the established methods, we simulated a whole brain treatment for the 10 year-old male phantom and a prostate treatment for the adult male phantom. Radiation doses to selected organs were calculated using the TPS and XVMC, and compared to each other. Organ average doses from the two methods matched within 7%, whereas maximum and minimum point doses differed up to 45%. The dosimetry methods and procedures established in this study will be useful for the reconstruction of organ dose to support

  15. Patient-Specific Quality Assurance for Prostate Cancer Patients Receiving Spot Scanning Proton Therapy Using Single-Field Uniform Dose

    SciTech Connect

    Zhu, X. Ronald; Poenisch, Falk; Song, Xiaofei; Johnson, Jennifer L.; Ciangaru, George; Taylor, M. Brad; Lii, Ming Fwu; Martin, Craig; Arjomandy, Bijan; Lee, Andrew K.; Choi, Seungtaek; Nguyen, Quynh nhu; Gillin, Michael T.; Sahoo, Narayan

    2011-10-01

    Purpose: To describe our experiences with patient-specific quality assurance (QA) for patients with prostate cancer receiving spot scanning proton therapy (SSPT) using single-field uniform dose (SFUD). Methods and Materials: The first group of 249 patients with prostate cancer treated with SSPT using SFUD was included in this work. The scanning-beam planning target volume and number of monitor units were recorded and checked for consistency. Patient-specific dosimetric measurements were performed, including the point dose for each plan, depth doses, and two-dimensional (2D) dose distribution in the planes perpendicular to the incident beam direction for each field at multiple depths. The {gamma}-index with 3% dose or 3-mm distance agreement criteria was used to evaluate the 2D dose distributions. Results: We observed a linear relationship between the number of monitor units and scanning-beam planning target volume. The difference between the measured and calculated point doses (mean {+-} SD) was 0.0% {+-} 0.7% (range, -2.9% to 1.8%). In general, the depth doses exhibited good agreement except at the distal end of the spread-out Bragg peak. The pass rate of {gamma}-index (mean {+-} SD) for 2D dose comparison was 96.2% {+-} 2.6% (range, 90-100%). Discrepancies between the measured and calculated dose distributions primarily resulted from the limitation of the model used by the treatment planning system. Conclusions: We have established a patient-specific QA program for prostate cancer patients receiving SSPT using SFUD.

  16. Radiation dose reduction in thoracic and abdomen-pelvic CT using tube current modulation: a phantom study.

    PubMed

    Sabarudin, Akmal; Mustafa, Zakira; Nassir, Khadijah Mohd; Hamid, Hamzaini Abdul; Sun, Zhonghua

    2015-01-01

    This phantom study was designed to compare the radiation dose in thoracic and abdomen-pelvic CT scans with and without use of tube current modulation (TCM). Effective dose (ED) and size-specific dose estimation (SSDE) were calculated with the absorbed doses measured at selective radiosensitive organs using a thermoluminescence dosimeter-100 (TLD-100). When compared to protocols without TCM, the ED and SSDE were reduced significantly with use of TCM for both the thoracic and abdomen-pelvic CT. With use of TCM, the ED was 6.50±0.29 mSv for thoracic and 6.01±0.20 mSv for the abdomen-pelvic CT protocols. However without use of TCM, the ED was 20.07±0.24 mSv and 17.30±0.41 mSv for the thoracic and abdomen-pelvic CT protocols, respectively. The corresponding SSDE was 10.18±0.48 mGy and 11.96±0.27 mGy for the thoracic and abdomen-pelvic CT protocols with TCM, and 31.56±0.43 mGy and 33.23±0.05 mGy for thoracic and abdomen-pelvic CT protocols without TCM, respectively. The highest absorbed dose was measured at the breast with 8.58±0.12 mGy in the TCM protocols and 51.52±14.72 mGy in the protocols without TCM during thoracic CT. In the abdomen-pelvic CT, the absorbed dose was highest at the skin with 9.30±1.28 mGy and 29.99±2.23 mGy in protocols with and without use of TCM, respectively. In conclusion, the TCM technique results in significant dose reduction; thus it is to be highly recommended in routine thoracic and abdomen-pelvic CT. PACS numbers: 87.57.Q-, 87.57.qp, 87.53.Bn.

  17. Radiation dose reduction in thoracic and abdomen-pelvic CT using tube current modulation: a phantom study.

    PubMed

    Sabarudin, Akmal; Mustafa, Zakira; Nassir, Khadijah Mohd; Hamid, Hamzaini Abdul; Sun, Zhonghua

    2014-01-08

    This phantom study was designed to compare the radiation dose in thoracic and abdomen-pelvic CT scans with and without use of tube current modulation (TCM). Effective dose (ED) and size-specific dose estimation (SSDE) were calculated with the absorbed doses measured at selective radiosensitive organs using a thermoluminescence dosimeter-100 (TLD-100). When compared to protocols without TCM, the ED and SSDE were reduced significantly with use of TCM for both the thoracic and abdomen-pelvic CT. With use of TCM, the ED was 6.50 ± 0.29 mSv for thoracic and 6.01 ± 0.20 mSv for the abdomen-pelvic CT protocols. However without use of TCM, the ED was 20.07 ± 0.24 mSv and 17.30 ± 0.41 mSv for the thoracic and abdomen-pelvic CT protocols, respectively. The corresponding SSDE was 10.18 ± 0.48 mGy and 11.96 ± 0.27 mGy for the thoracic and abdomen-pelvic CT protocols with TCM, and 31.56 ± 0.43 mGy and 33.23 ± 0.05 mGy for thoracic and abdomen-pelvic CT protocols without TCM, respectively. The highest absorbed dose was measured at the breast with 8.58 ± 0.12 mGy in the TCM protocols and 51.52 ± 14.72 mGy in the protocols without TCM during thoracic CT. In the abdomen-pelvic CT, the absorbed dose was highest at the skin with 9.30 ± 1.28mGy and 29.99 ± 2.23 mGy in protocols with and without use of TCM, respectively. In conclusion, the TCM technique results in significant dose reduction; thus it is to be highly recommended in routine thoracic and abdomen-pelvic CT.

  18. Occupational dose reduction at nuclear power plants: Annotated bibliography of selected readings in radiation protection and ALARA. Volume 8

    SciTech Connect

    Sullivan, S.G.; Khan, T.A.; Xie, J.W.

    1995-05-01

    The ALARA Center at Brookhaven National Laboratory publishes a series of bibliographies of selected readings in radiation protection and ALARA in a continuing effort to collect and disseminate information on radiation dose reduction at nuclear power plants. This volume 8 of the series. The abstracts in this bibliography were selected form proceedings of technical meetings and conference journals, research reports, and searches of the Energy Science and Technology database of the US Department of Energy. The subject material of these abstracts relates to the many aspects of radiation protection and dose reduction, and ranges form use of robotics, to operational health physics, to water chemistry. Material on the design, planning, and management of nuclear power stations is included, as well as information on decommissioning and safe storage efforts. Volume 8 contains 232 abstracts, an author index, and a subject index. The author index is specific for this volume. The subject index is cumulative and lists all abstract numbers from volumes 1 to 8. The numbers in boldface indicate the abstracts in this volume; the numbers not in boldface represent abstracts in previous volumes.

  19. Occupational dose reduction at nuclear power plants: Annotated bibliography of selected readings in radiation protection and ALARA. Volume 7

    SciTech Connect

    Kaurin, D.G.; Khan, T.A.; Sullivan, S.G.; Baum, J.W.

    1993-07-01

    The ALARA Center at Brookhaven National Laboratory publishes a series of bibliographies of selected readings in radiation protection and ALARA in the continuing effort to collect and disseminate information on radiation dose reduction at nuclear power plants. This is volume 7 of the series. The abstracts in this bibliography were selected from proceedings of technical meetings and conferences, journals, research reports, and searches of the Energy Science and Technology database of the US Department of Energy. The subject material of these abstracts relates to radiation protection and dose reduction, and ranges from use of robotics to operational health physics, to water chemistry. Material on the design, planning, and management of nuclear power stations is included, as well as information on decommissioning and safe storage efforts. Volume 7 contains 293 abstract, an author index, and a subject index. The author index is specific for this volume. The subject index is cumulative and lists all abstract numbers from volumes 1 to 7. The numbers in boldface indicate the abstracts in this volume; the numbers not in boldface represent abstracts in previous volumes.

  20. Reduction in stray radiation dose using a body-shielding device during external radiation therapy.

    PubMed

    Zhang, Shuxu; Jiang, Shaohui; Zhang, Quanbin; Lin, Shengqu; Wang, Ruihao; Zhou, Xiang; Zhang, Guoqian; Lei, Huaiyu; Yu, Hui

    2017-03-01

    With the purpose of reducing stray radiation dose (SRD) in out-of-field region (OFR) during radiotherapy with 6 MV intensity-modulated radiation therapy (IMRT), a body-shielding device (BSD) was prepared according to the measurements obtained in experimental testing. In experimental testing, optimal shielding conditions, such as 1 mm lead, 2 mm lead, and 1 mm lead plus 10 mm bolus, were investigated along the medial axis of a phantom using thermoluminescent dosimeters (TLDs). The SRDs at distances from field edge were then measured and analyzed for a clinical IMRT treatment plan for nasopharyngeal carcinoma before and after shielding using the BSD. In addition, SRDs in anterior, posterior, left and right directions of phantom were investigated with and without shielding, respectively. Also, the SRD at the bottom of treatment couch was measured. SRD decreased exponentially to a constant value with increasing distance from field edge. The shielding rate was 50%-80%; however, there were no significant differences in SRDs when shielded by 1 mm lead, 2 mm lead, or 1 mm lead plus 10 mm bolus (P>0.05). Importantly, the 10 mm bolus absorbed back-scattering radiation due to the interaction between photons and lead. As a result, 1 mm lead plus 10 mm bolus was selected to prepare the BSD. After shielding with BSD, total SRDs in the OFR decreased to almost 50% of those without shielding when irradiated with IMRT beams. Due to the effects of treatment couch and gantry angle, SRDs at distances were not identical in anterior, posterior, left and right direction of phantom without BSD. As higher dose in anterior and lower dose in posterior, SRDs were substantial similarities after shielding. There was no significant difference in SRDs for left and right directions with or without shielding. Interestingly, SRDs in the four directions were similar after shielding. From these results, the BSD developed in this study may significantly reduce SRD in the OFR during

  1. Dose calculation software for helical tomotherapy, utilizing patient CT data to calculate an independent three-dimensional dose cube

    SciTech Connect

    Thomas, Simon J.; Eyre, Katie R.; Tudor, G. Samuel J.; Fairfoul, Jamie

    2012-01-15

    Purpose: Treatment plans for the TomoTherapy unit are produced with a planning system that is integral to the unit. The authors have produced an independent dose calculation system, to enable plans to be recalculated in three dimensions, using the patient's CT data. Methods: Software has been written using MATLAB. The DICOM-RT plan object is used to determine the treatment parameters used, including the treatment sinogram. Each projection of the sinogram is segmented and used to calculate dose at multiple calculation points in a three-dimensional grid using tables of measured beam data. A fast ray-trace algorithm is used to determine effective depth for each projection angle at each calculation point. Calculations were performed on a standard desktop personal computer, with a 2.6 GHz Pentium, running Windows XP. Results: The time to perform a calculation, for 3375 points averaged 1 min 23 s for prostate plans and 3 min 40 s for head and neck plans. The mean dose within the 50% isodose was calculated and compared with the predictions of the TomoTherapy planning system. When the modified CT (which includes the TomoTherapy couch) was used, the mean difference for ten prostate patients, was -0.4% (range -0.9% to +0.3%). With the original CT (which included the CT couch), the mean difference was -1.0% (range -1.7% to 0.0%). The number of points agreeing with a gamma 3%/3 mm averaged 99.2% with the modified CT, 96.3% with the original CT. For ten head and neck patients, for the modified and original CT, respectively, the mean difference was +1.1% (range -0.4% to +3.1%) and 1.1% (range -0.4% to +3.0%) with 94.4% and 95.4% passing a gamma 4%/4 mm. The ability of the program to detect a variety of simulated errors has been tested. Conclusions: By using the patient's CT data, the independent dose calculation performs checks that are not performed by a measurement in a cylindrical phantom. This enables it to be used either as an additional check or to replace phantom

  2. Population pharmacokinetics and dose optimisation of ritonavir-boosted atazanavir in Thai HIV-infected patients.

    PubMed

    Punyawudho, Baralee; Thammajaruk, Narukjaporn; Ruxrungtham, Kiat; Avihingsanon, Anchalee

    2017-03-01

    There is evidence that Thai patients receiving standard doses of ritonavir (RTV)-boosted atazanavir (ATV/r) have high exposure to atazanavir (ATV) leading to a higher risk of toxicity. A lower dose of ATV/r may provide adequate exposure in this population. However, pharmacokinetic data on ATV/r in Thai patients required for dose adjustment are limited. This study aimed to develop a population pharmacokinetic model of ATV/r and to determine the influence of patient characteristics on ATV pharmacokinetics. Monte Carlo simulations were performed to estimate the proportion of patients achieving target ATV trough concentration (Ctrough) with the standard ATV/r dose of 300/100 mg and a low dose of 200/100 mg once daily (OD). A total of 127 Thai HIV-infected patients were included in this study. One random blood sample was collected to determine ATV and RTV concentrations at each clinic visit from 100 patients. Intensive data from 27 patients enrolled in previous studies were also included. Data were analysed using the non-linear mixed-effects modelling approach. A one-compartment model with first-order absorption and elimination and absorption lag time best described the data. The population mean clearance of ATV/r was 4.93 L/h in female patients and was 28.7% higher in male patients. Simulation results showed a higher proportion of patients achieving ATV Ctrough within the target range with ATV/r 200/100 mg compared with 300/100 mg. The 200/100 mg OD dose of ATV/r provides adequate ATV exposure in Thai HIV-infected patients. Therefore, a lower dose of ATV/r should be considered for Thai and Asian populations.

  3. Computation of thyroid doses and carcinogenic radiation risks to patients undergoing neck CT examinations.

    PubMed

    Huda, Walter; Spampinato, Maria V; Tipnis, Sameer V; Magill, Dennise

    2013-10-01

    The aim of the study was to investigate how differences in patient anatomy and CT technical factors in neck CT impact on thyroid doses and the corresponding carcinogenic risks. The CTDIvol and dose-length product used in 11 consecutive neck CT studies, as well as data on automatic exposure control (AEC) tube current variation(s) from the image DICOM header, were recorded. For each CT image that included the thyroid, the mass equivalent water cylinder was estimated based on the patient cross-sectional area and average relative attenuation coefficient (Hounsfield unit, HU). Patient thyroid doses were estimated by accounting for radiation intensity at the location of the patient's thyroid, patient size and the scan length. Thyroid doses were used to estimate thyroid cancer risks as a function of patient demographics using risk factors in BEIR VII. The length of the thyroid glands ranged from 21 to 54 mm with an average length of 42 ± 12 mm. Water cylinder diameters corresponding to the central slice through the patient thyroid ranged from 18 to 32 cm with a mean of 25 ± 5 cm. The average CTDIvol (32-cm phantom) used to perform these scans was 26 ± 6 mGy, but the use of an AEC increased the tube current by an average of 44 % at the thyroid mid-point. Thyroid doses ranged from 29 to 80 mGy, with an average of 55 ± 19 mGy. A 20-y-old female receiving the highest thyroid dose of 80 mGy would have a thyroid cancer risk of nearly 0.1 %, but radiation risks decreased very rapidly with increasing patient age. The key factors that affect thyroid doses in neck CT examinations are the radiation intensity at the thyroid location and the size of the patient. The corresponding patient thyroid cancer risk is markedly influenced by patient sex and age.

  4. The influence of patient centering on CT dose and image noise.

    PubMed

    Toth, Thomas; Ge, Zhanyu; Daly, Michael P

    2007-07-01

    Although x-ray intensity shaping filters (bowtie filters) have been used since the introduction of some of the earliest CT scanner models, the clinical implications on dose and noise are not well understood. To achieve the intended dose and noise advantage requires the patient to be centered in the scan field of view. In this study we explore the implications of patient centering in clinical practice. We scanned various size and shape phantoms on a GE LightSpeed VCT scanner using each available source filter with the phantom centers positioned at 0, 3, and 6 cm below the center of rotation (isocenter). Surface doses were measured along with image noise over a large image region. Regression models of surface dose and noise were generated as a function of phantom size and centering error. Methods were also developed to determine the amount of miscentering using a scout scan projection radiograph (SPR). These models were then used to retrospectively evaluate 273 adult body patients for clinical implications. When miscentered by 3 and 6 cm, the surface dose on a 32 cm CTDI phantom increased by 18% and 41% while image noise also increased by 6% and 22%. The retrospective analysis of adult body scout SPR scans shows that 46% of patients were miscentered in elevation by 20-60 mm with a mean position 23 mm below the center of rotation (isocenter). The analysis indicated a surface dose penalty of up to 140% with a mean dose penalty of 33% assuming that tube current is increased to compensate for the increased noise due to miscentering. Clinical image quality and dose efficiency can be improved on scanners with bowtie filters if care is exercised when positioning patients. Automatically providing patient specific centering and scan parameter selection information can help the technologist improve workflow, achieve more consistent image quality and reduce patient dose.

  5. Dosing and safety of cyclosporine in patients with severe brain injury

    PubMed Central

    Hatton, Jimmi; Rosbolt, Bonnie; Empey, Philip; Kryscio, Richard; Young, Byron

    2009-01-01

    Object Cyclosporine neuroprotection has been reported in brain injury models but safety and dosing guidelines have not been determined in humans with severe traumatic brain injury (TBI). The purpose of this investigation was to establish the safety of cyclosporine using 4 clinically relevant dosing schemes. Methods The authors performed a prospective, blinded, placebo-controlled, randomized, dose-escalation trial of cyclosporine administration initiated within 8 hours of TBI (Glasgow Coma Scale score range 4–8; motor score range 2–5). Four dosing cohorts (8 patients treated with cyclosporine and 2 receiving placebo treatment per cohort) received cyclosporine (1.25–5 mg/kg/day) or placebo in 2 divided doses (Cohorts I–III) or continuous infusion (Cohort IV) over 72 hours. Adverse events and outcome were monitored for 6 months. Results Forty patients were enrolled over 3 years (cyclosporine cohorts, 24 male and 8 female patients; placebo group, 8 male patients). Systemic trough concentrations were below 250 ng/ml during intermittent doses. Higher blood concentrations were observed in Cohorts III and IV. There was no significant difference in immunological effects, adverse events, infection, renal dysfunction, or seizures. Mortality rate was not affected by cyclosporine administration, independent of dose, compared with placebo (6 of 32 patients receiving cyclosporine and 2 of 8 receiving placebo died, p > 0.05). At 6 months, a dose-related improvement in favorable outcome was observed in cyclosporine-treated patients (p < 0.05). Conclusions In patients with acute TBI who received cyclosporine at doses up to 5 mg/kg/day, administered intravenously, with treatment initiated within 8 hours of injury, the rate of mortality or other adverse events was not significantly different from that of the placebo group. PMID:18826358

  6. Reinitiating Warfarin: Relationships Between Dose and Selected Patient, Clinical and Hospital Measures

    PubMed Central

    Leonhard, Lucas G.; Berg, Richard L.; Burmester, James K.; Mazza, Joseph J.; Schmelzer, John R.; Yale, Steven H.

    2015-01-01

    Background Warfarin is an oral anticoagulant used in the long-term treatment/prevention of venothromboembolic disease. Patients undergoing elective surgical and non-surgical procedures may require temporary warfarin discontinuation followed by reinitiation after their procedure. Because little information is available regarding best methods for warfarin reinitiation, we investigated current practices to inform management decisions. Methods Subjects were required to have a known and stable warfarin dose prior to discontinuation, which was operationalized by requiring, within 7-days prior to discontinuation, that they have at least one INR in therapeutic range (2.0–3.5), no INR(s) out of range, and no more than a 15% change in warfarin dose. Stable dose prior to discontinuation was defined as the average daily dose received in the 7 days immediately prior to discontinuation. Reinitiation dose was defined as the average daily dose received in the first 3 days after warfarin was restarted. Subjects were divided into three groups based on whether they received approximately the same, a higher, or a lower dose at reinitiation and were also grouped by calendar time into three distinct periods that reflected differing levels of availability of electronic and patient care data that may impact reinitiation dose decisions. These groupings facilitated analyses and descriptions of trends in reinitiation dosing and supported other analyses, including tests for association between dose group and selected subject demographic, clinical, medication and hospitalization measures. All study data were abstracted from Marshfield Clinic electronic patient care and administrative databases and electronic patient care databases from Ministry St. Joseph’s Hospital (Marshfield, WI). Results We identified 205 subjects with warfarin temporarily discontinued between 1994 and 2012: 99 subjects in same dose group, 32 subjects in the low group, and 74 subjects in the high group. Because

  7. Feasibility study of patient-specific quality assurance system for high-dose-rate brachytherapy in patients with cervical cancer

    NASA Astrophysics Data System (ADS)

    Lee, Boram; Ahn, Sung Hwan; Kim, Hyeyoung; Han, Youngyih; Huh, Seung Jae; Kim, Jin Sung; Kim, Dong Wook; Sim, Jina; Yoon, Myonggeun

    2016-04-01

    This study was conducted for the purpose of establishing a quality-assurance (QA) system for brachytherapy that can ensure patient-specific QA by enhancing dosimetric accuracy for the patient's therapy plan. To measure the point-absorbed dose and the 2D dose distribution for the patient's therapy plan, we fabricated a solid phantom that allowed for the insertion of an applicator for patient-specific QA and used an ion chamber and a film as measuring devices. The patient treatment plan was exported to the QA dose-calculation software, which calculated the time weight of dwell position stored in the plan DICOM (Digital Imaging and Communications in Medicine) file to obtain an overall beam quality correction factor, and that correction was applied to the dose calculations. Experiments were conducted after importing the patient's treatment planning source data for the fabricated phantom and inserting the applicator, ion chamber, and film into the phantom. On completion of dose delivery, the doses to the ion chamber and film were checked against the corresponding treatment plan to evaluate the dosimetric accuracy. For experimental purposes, five treatment plans were randomly selected. The beam quality correction factors for ovoid and tandem brachytherapy applicators were found to be 1.15 and 1.10 - 1.12, respectively. The beam quality correction factor in tandem fluctuated by approximately 2%, depending on the changes in the dwell position. The doses measured by using the ion chamber showed differences ranging from -2.4% to 0.6%, compared to the planned doses. As for the film, the passing rate was 90% or higher when assessed using a gamma value of the local dose difference of 3% and a distance to agreement of 3 mm. The results show that the self-fabricated phantom was suitable for QA in clinical settings. The proposed patient-specific QA for the treatment planning is expected to contribute to reduce dosimetric errors in brachytherapy and, thus, to enhancing treatment

  8. Noise correlation in CBCT projection data and its application for noise reduction in low-dose CBCT

    SciTech Connect

    Zhang, Hua; Ouyang, Luo; Wang, Jing E-mail: jing.wang@utsouthwestern.edu; Ma, Jianhua E-mail: jing.wang@utsouthwestern.edu; Huang, Jing; Chen, Wufan

    2014-03-15

    Purpose: To study the noise correlation properties of cone-beam CT (CBCT) projection data and to incorporate the noise correlation information to a statistics-based projection restoration algorithm for noise reduction in low-dose CBCT. Methods: In this study, the authors systematically investigated the noise correlation properties among detector bins of CBCT projection data by analyzing repeated projection measurements. The measurements were performed on a TrueBeam onboard CBCT imaging system with a 4030CB flat panel detector. An anthropomorphic male pelvis phantom was used to acquire 500 repeated projection data at six different dose levels from 0.1 to 1.6 mAs per projection at three fixed angles. To minimize the influence of the lag effect, lag correction was performed on the consecutively acquired projection data. The noise correlation coefficient between detector bin pairs was calculated from the corrected projection data. The noise correlation among CBCT projection data was then incorporated into the covariance matrix of the penalized weighted least-squares (PWLS) criterion for noise reduction of low-dose CBCT. Results: The analyses of the repeated measurements show that noise correlation coefficients are nonzero between the nearest neighboring bins of CBCT projection data. The average noise correlation coefficients for the first- and second-order neighbors are 0.20 and 0.06, respectively. The noise correlation coefficients are independent of the dose level. Reconstruction of the pelvis phantom shows that the PWLS criterion with consideration of noise correlation (PWLS-Cor) results in a lower noise level as compared to the PWLS criterion without considering the noise correlation (PWLS-Dia) at the matched resolution. At the 2.0 mm resolution level in the axial-plane noise resolution tradeoff analysis, the noise level of the PWLS-Cor reconstruction is 6.3% lower than that of the PWLS-Dia reconstruction. Conclusions: Noise is correlated among nearest neighboring

  9. Therapeutic immunoglobulin should be dosed by clinical outcome rather than by body weight in obese patients.

    PubMed

    Hodkinson, J P; Lucas, M; Lee, M; Harrison, M; Lunn, M P; Chapel, H

    2015-07-01

    There are currently no data to support the suggestion that the dose of therapeutic immunoglobulin (Ig) should be capped in obese patients for pharmacokinetic (PK), safety and economic reasons. We compared IgG trough levels, increment and efficiency in matched pairs of obese and lean patients receiving either replacement or immunomodulatory immunoglobulin therapy. Thirty-one obese patients were matched with a clinically equivalent lean patient across a range of indications, including primary antibody deficiency or autoimmune peripheral neuropathy. Comprehensive matching was carried out using ongoing research databases at two centres in which the dose of Ig was based on clinical outcome, whether infection prevention or documented clinical neurological stability. The IgG trough or steady state levels, IgG increments and Ig efficiencies at times of clinical stability were compared between the obese and lean cohorts and within the matched pairs. This study shows that, at a population level, obese patients achieved a higher trough and increment (but not efficiency) for a given weight-adjusted dose compared with the lean patients. However at an individual patient level there were significant exceptions to this correlation, and upon sub-group analysis no significant difference was found between obese and lean patients receiving replacement therapy. Across all dose regimens a high body mass index (BMI) cannot be used to predict reliably the patients in whom dose restriction is clinically appropriate.

  10. Therapeutic immunoglobulin should be dosed by clinical outcome rather than by body weight in obese patients

    PubMed Central

    Hodkinson, J P; Lucas, M; Lee, M; Harrison, M; Lunn, M P; Chapel, H

    2015-01-01

    There are currently no data to support the suggestion that the dose of therapeutic immunoglobulin (Ig) should be capped in obese patients for pharmacokinetic (PK), safety and economic reasons. We compared IgG trough levels, increment and efficiency in matched pairs of obese and lean patients receiving either replacement or immunomodulatory immunoglobulin therapy. Thirty-one obese patients were matched with a clinically equivalent lean patient across a range of indications, including primary antibody deficiency or autoimmune peripheral neuropathy. Comprehensive matching was carried out using ongoing research databases at two centres in which the dose of Ig was based on clinical outcome, whether infection prevention or documented clinical neurological stability. The IgG trough or steady state levels, IgG increments and Ig efficiencies at times of clinical stability were compared between the obese and lean cohorts and within the matched pairs. This study shows that, at a population level, obese patients achieved a higher trough and increment (but not efficiency) for a given weight-adjusted dose compared with the lean patients. However at an individual patient level there were significant exceptions to this correlation, and upon sub-group analysis no significant difference was found between obese and lean patients receiving replacement therapy. Across all dose regimens a high body mass index (BMI) cannot be used to predict reliably the patients in whom dose restriction is clinically appropriate. PMID:25731216

  11. Dose Adjustment for Normal Eating: A Role for the Expert Patient?

    PubMed Central

    2014-01-01

    The Dose Adjustment for Normal Eating (DAFNE) programme of intensive insulin therapy for type 1 diabetes provides a structured educational intervention to improve glycemic control, reduce hypoglycemia and improve quality of life. Enhancement of self-management skills is a key element of DAFNE and patients acquire detailed skills in insulin dose adjustment. Following DAFNE training, patients report improved confidence in their ability to manage their own insulin dosing, but generally still seek and require the assistance of health professionals when making substantial changes to their insulin regimens. Some DAFNE trained patients may be able to assist their peers in aspects of diabetes management within a group environment, but widespread introduction of the expert patient/peer educator role in the self-management of type 1 diabetes, in particular related to insulin dose management, would require formal and detailed evaluation, preferably in randomized controlled clinical trials, before being introduced into routine clinical practice. PMID:24851201

  12. Reference dose levels for patients undergoing common diagnostic X-ray examinations in Irish hospitals.

    PubMed

    Johnston, D A; Brennan, P C

    2000-04-01

    Wide variations in patient dose for the same type of X-ray examination have been evident from various international dose surveys. Reference dose levels provide a framework to reduce this variability and aid in the optimization of radiation protection. The aim of this study was to establish, for the first time, a baseline for national reference dose levels in Ireland for four of the most common X-ray examinations: chest, abdomen, pelvis and lumbar spine. Measurements of entrance surface dose using thermoluminescent dosemeters (TLDs) for these four X-ray examinations were performed on 10 patients in each of 16 randomly selected hospitals. This represented 42% of Irish hospitals applicable to this study. Results have shown wide variation of mean hospital doses, from a factor of 3 for an anteroposterior lumbar spine to a factor of 23 for the chest X-ray. The difference between maximum and minimum individual patient dose values varied up to a factor of 75. Reasons for these dose variations were complex but, in general, low tube potential, high mAs and low filtration were associated with high-dose hospitals. This study also demonstrated lower reference dose levels of up to 40% when compared with those established by the UK and the Commission of the European Communities for four out of six projections. Only the chest X-ray exhibited a similar reference level to those established elsewhere. This emphasizes the importance of each country establishing its own reference dose levels that are appropriate to their own radiographic techniques and practices in order to optimize patient protection.

  13. Phase Ib Safety, Two-Dose Study of MultiGeneAngio in Patients with Chronic Critical Limb Ischemia.

    PubMed

    Flugelman, Moshe Y; Halak, Moshe; Yoffe, Boris; Schneiderman, Jacob; Rubinstein, Chen; Bloom, Allan-Isaac; Weinmann, Eran; Goldin, Ilya; Ginzburg, Victor; Mayzler, Olga; Hoffman, Aaron; Koren, Belly; Gershtein, Diana; Inbar, Michal; Hutoran, Marina; Tsaba, Adili

    2017-03-01

    Critical limb ischemia (CLI) is the most severe presentation of peripheral arterial disease. We developed cell-based therapy entailing intra-arterial injection of autologous venous endothelial cells (ECs) modified to express angiopoietin 1, combined with autologous venous smooth muscle cells (SMCs) modified to express vascular endothelial growth factor. This combination promoted arteriogenesis in animal models and was safe in patients with limiting claudication. In an open-label, phase Ib study, we assessed the safety and efficacy of this therapy in CLI patients who failed or were unsuitable for surgery or intravascular intervention. Of 23 patients enrolled, 18 with rest pain or non-healing ulcers (Rutherford categories 4 and 5) were treated according to protocol, and 5 with significant tissue loss (Rutherford 6) were treated under compassionate treatment. Patients were assigned randomly to receive 1 × 10(7) or 5 × 10(7) (EC-to-SMC ratio, 1:1) of the cell combination. One-year amputation-free survival rate was 72% (13/18) for Rutherford 4 and 5 patients; all 5 patients with Rutherford 6 underwent amputation. Of the 12 with unhealing ulcers at dosing, 6 had complete healing and 2 others had >66% reduction in ulcer size. Outcomes did not differ between the dose groups. No severe adverse events were observed related to the therapy.

  14. Reduction of the secondary neutron dose in passively scattered proton radiotherapy, using an optimized pre-collimator/collimator

    PubMed Central

    Brenner, David J; Elliston, Carl D; Hall, Eric J; Paganetti, Harald

    2013-01-01

    Proton radiotherapy represents a potential major advance in cancer therapy. Most current proton beams are spread out to cover the tumor using passive scattering and collimation, resulting in an extra whole-body high-energy neutron dose, primarily from proton interactions with the final collimator. There is considerable uncertainty as to the carcinogenic potential of low doses of high-energy neutrons, and thus we investigate whether this neutron dose can be significantly reduced without major modifications to passively scattered proton beam lines. Our goal is to optimize the design features of a patient-specific collimator or pre-collimator/collimator assembly. There are a number of often contradictory design features, in terms of geometry and material, involved in an optimal design. For example, plastic or hybrid plastic/metal collimators have a number of advantages. We quantify these design issues, and investigate the practical balances that can be achieved to significantly reduce the neutron dose without major alterations to the beamline design or function. Given that the majority of proton therapy treatments, at least for the next few years, will use passive scattering techniques, reducing the associated neutron-related risks by simple modifications of the collimator assembly design is a desirable goal. PMID:19779218

  15. The relationship between organ dose and patient size in tube current modulated adult thoracic CT scans

    NASA Astrophysics Data System (ADS)

    Khatonabadi, Maryam; Zhang, Di; Yang, Jeffrey; DeMarco, John J.; Cagnon, Chris C.; McNitt-Gray, Michael F.

    2012-03-01

    Recently published AAPM Task Group 204 developed conversion coefficients that use scanner reported CTDIvol to estimate dose to the center of patient undergoing fixed tube current body exam. However, most performed CT exams use TCM to reduce dose to patients. Therefore, the purpose of this study was to investigate the correlation between organ dose and a variety of patient size metrics in adult chest CT scans that use tube current modulation (TCM). Monte Carlo simulations were performed for 32 voxelized models with contoured lungs and glandular breasts tissue, consisting of females and males. These simulations made use of patient's actual TCM data to estimate organ dose. Using image data, different size metrics were calculated, these measurements were all performed on one slice, at the level of patient's nipple. Estimated doses were normalized by scanner-reported CTDIvol and plotted versus different metrics. CTDIvol values were plotted versus different metrics to look at scanner's output versus size. The metrics performed similarly in terms of correlating with organ dose. Looking at each gender separately, for male models normalized lung dose showed a better linear correlation (r2=0.91) with effective diameter, while female models showed higher correlation (r2=0.59) with the anterior-posterior measurement. There was essentially no correlation observed between size and CTDIvol-normalized breast dose. However, a linear relationship was observed between absolute breast dose and size. Dose to lungs and breasts were consistently higher in females with similar size as males which could be due to shape and composition differences between genders in the thoracic region.

  16. Moving from gamma passing rates to patient DVH-based QA metrics in pretreatment dose QA

    SciTech Connect

    Zhen, Heming; Nelms, Benjamin E.; Tome, Wolfgang A.

    2011-10-15

    Purpose: The purpose of this work is to explore the usefulness of the gamma passing rate metric for per-patient, pretreatment dose QA and to validate a novel patient-dose/DVH-based method and its accuracy and correlation. Specifically, correlations between: (1) gamma passing rates for three 3D dosimeter detector geometries vs clinically relevant patient DVH-based metrics; (2) Gamma passing rates of whole patient dose grids vs DVH-based metrics, (3) gamma passing rates filtered by region of interest (ROI) vs DVH-based metrics, and (4) the capability of a novel software algorithm that estimates corrected patient Dose-DVH based on conventional phan-tom QA data are analyzed. Methods: Ninety six unique ''imperfect'' step-and-shoot IMRT plans were generated by applying four different types of errors on 24 clinical Head/Neck patients. The 3D patient doses as well as the dose to a cylindrical QA phantom were then recalculated using an error-free beam model to serve as a simulated measurement for comparison. Resulting deviations to the planned vs simulated measured DVH-based metrics were generated, as were gamma passing rates for a variety of difference/distance criteria covering: dose-in-phantom comparisons and dose-in-patient comparisons, with the in-patient results calculated both over the whole grid and per-ROI volume. Finally, patient dose and DVH were predicted using the conventional per-beam planar data as input into a commercial ''planned dose perturbation'' (PDP) algorithm, and the results of these predicted DVH-based metrics were compared to the known values. Results: A range of weak to moderate correlations were found between clinically relevant patient DVH metrics (CTV-D95, parotid D{sub mean}, spinal cord D1cc, and larynx D{sub mean}) and both 3D detector and 3D patient gamma passing rate (3%/3 mm, 2%/2 mm) for dose-in-phantom along with dose-in-patient for both whole patient volume and filtered per-ROI. There was considerable scatter in the gamma passing rate

  17. Evaluation of a New Vancomycin Dosing Protocol in Morbidly Obese Patients

    PubMed Central

    Kosmisky, Desiree E.; Griffiths, Carrie L.; Templin, Megan A.; Norton, James

    2015-01-01

    Background: Optimal dosing of vancomycin in morbidly obese patients (>100 kg and at least 140% of their ideal body weight) has not been determined. Conventional dosing strategies have led to the observation of supratherapeutic trough concentrations (>20 mcg/mL). Objective: To evaluate the effectiveness of a new vancomycin dosing protocol in morbidly obese patients in achieving therapeutic trough concentrations between 10 and 20 mcg/mL and to determine patient-specific factors influencing the trough concentration attained. Methodology: A single-center, retrospective chart review included morbidly obese adult patients with a pharmacy-to-dose vancomycin consult and at least 1 trough concentration obtained at steady state. Patients were excluded if they had a creatinine clearance (CrCl) less than 35 mL/min or unstable renal function, were not dosed according to the revised protocol, or received vancomycin prior to initiation of the protocol. Results: Of the 48 patients included, 17 (35.4%) achieved a therapeutic vancomycin trough concentration. Subtherapeutic concentrations (<10 mcg/mL) were observed in 27 patients (56.3%) and supratherapeutic concentrations were observed in 4 (8.3%) patients. Age less than 45 years and CrCl greater than 100 mL/min were associated with subtherapeutic trough concentrations. Conclusion: This study demonstrates that the revised vancomycin dosing protocol led to the attainment of therapeutic trough concentrations in 35.4% of patients. The majority had subtherapeutic concentrations, which increases the risk of treatment failures and resistance. Further study is needed to determine the optimal dosing strategy in this patient population. PMID:26912920

  18. Evaluation of in vivo dose measurements for patients undergoing electron boost treatments.

    PubMed

    Verney, J N; Morgan, A M

    2001-06-01

    This study evaluated p-type silicon diodes for use in in vivo dosimetry in clinical electron beams. A calibrated p-type silicon diode detector was used to measure the dose received by the patient in the centre of the field. Readings were corrected for energy, temperature and stand-off of the electron applicator from the patient surface. The mean difference between measured and prescribed dose was 1.04% (95% CI 0.72 to 1.36 %).

  19. High-dose fractionated radiation therapy for select patients with brain metastases

    SciTech Connect

    Pezner, R.D.; Lipsett, J.A.; Archambeau, J.O.; Fine, R.M.; Moss, W.T.

    1981-08-01

    Four patients with metastases to the brain were treated by high-dose fractionated radiation therapy. In all four cases, a complete response and prolonged disease-free survival could be documented. Unlike the standard therapy for such patients (i.e., craniotomy and postoperative irradiation), high-dose fractionated radiation therapy carries no operative risk and can encompass multiple brain metastases and metastases in deep or critical intracranial sites. The risk of radiotherapy side effects in the brain is discussed.

  20. Reduction of radiation risks in patients undergoing some X-ray examinations by using optimal projections: A Monte Carlo program-based mathematical calculation

    PubMed Central

    Chaparian, A.; Kanani, A.; Baghbanian, M.

    2014-01-01

    The objectives of this paper were calculation and comparison of the effective doses, the risks of exposure-induced cancer, and dose reduction in the gonads for male and female patients in different projections of some X-ray examinations. Radiographies of lumbar spine [in the eight projections of anteroposterior (AP), posteroanterior (PA), right lateral (RLAT), left lateral (LLAT), right anterior-posterior oblique (RAO), left anterior-posterior oblique (LAO), right posterior-anterior oblique (RPO), and left posterior-anterior oblique (LPO)], abdomen (in the two projections of AP and PA), and pelvis (in the two projections of AP and PA) were investigated. A solid-state dosimeter was used for the measuring of the entrance skin exposure. A Monte Carlo program was used for calculation of effective doses, the risks of radiation-induced cancer, and doses to the gonads related to the different projections. Results of this study showed that PA projection of abdomen, lumbar spine, and pelvis radiographies caused 50%-57% lower effective doses than AP projection and 50%-60% reduction in radiation risks. Also use of LAO projection of lumbar spine X-ray examination caused 53% lower effective dose than RPO projection and 56% and 63% reduction in radiation risk for male and female, respectively, and RAO projection caused 28% lower effective dose than LPO projection and 52% and 39% reduction in radiation risk for males and females, respectively. About dose reduction in the gonads, using of the PA position rather than AP in the radiographies of the abdomen, lumbar spine, and pelvis can result in reduction of the ovaries doses in women, 38%, 31%, and 25%, respectively and reduction of the testicles doses in males, 76%, 86%, and 94%, respectively. Also for oblique projections of lumbar spine X-ray examination, with employment of LAO rather than RPO and also RAO rather than LPO, demonstrated 22% and 13% reductions to the ovaries doses and 66% and 54% reductions in the testicles doses

  1. Comparison of fractionated dose versus bolus dose injection in spinal anaesthesia for patients undergoing elective caesarean section: A randomised, double-blind study

    PubMed Central

    Badheka, Jigisha Prahaladray; Oza, Vrinda Pravinbhai; Vyas, Ashutosh; Baria, Deepika; Nehra, Poonam; Babu, Thomas

    2017-01-01

    Background and Aims: Spinal anaesthesia (SA) with bolus dose has rapid onset but may precipitate hypotension. When we inject local anaesthetic in fractions with a time gap, it provides a dense block with haemodynamic stability and also prolongs the duration of analgesia. We aimed to compare fractionated dose with bolus dose in SA for haemodynamic stability and duration of analgesia in patients undergoing elective lower segment caesarean section (LSCS). Methods: After clearance from the Institutional Ethics Committee, the study was carried out in sixty patients undergoing elective LSCS. Patients were divided into two groups. Group B patients received single bolus SA with injection bupivacaine heavy (0.5%) and Group F patients fractionated dose with two-third of the total dose of injection bupivacaine heavy (0.5%) given initially followed by one-third dose after 90 s. Time of onset and regression of sensory and motor blockage, intraoperative haemodynamics and duration of analgesia were recorded and analysed with Student's unpaired t-test. Result: All the patients were haemodynamically stable in Group F as compared to Group B. Five patients in Group F and fourteen patients in Group B required vasopressor. Duration of sensory and motor block and duration of analgesia were longer in Group F (273.83 ± 20.62 min) compared to Group B (231.5 ± 31.87 min) P < 0.05. Conclusion: Fractionated dose of SA provides greater haemodynamic stability and longer duration of analgesia compared to bolus dose. PMID:28216705

  2. Reductions in carotid chemoreceptor activity with low-dose dopamine improves baroreflex control of heart rate during hypoxia in humans.

    PubMed

    Mozer, Michael T; Holbein, Walter W; Joyner, Michael J; Curry, Timothy B; Limberg, Jacqueline K

    2016-07-01

    The purpose of the present investigation was to examine the contribution of the carotid body chemoreceptors to changes in baroreflex control of heart rate with exposure to hypoxia. We hypothesized spontaneous cardiac baroreflex sensitivity (scBRS) would be reduced with hypoxia and this effect would be blunted when carotid chemoreceptor activity was reduced with low-dose dopamine. Fifteen healthy adults (11 M/4 F) completed two visits randomized to intravenous dopamine or placebo (saline). On each visit, subjects were exposed to 5-min normoxia (~99% SpO2), followed by 5-min hypoxia (~84% SpO2). Blood pressure (intra-arterial catheter) and heart rate (ECG) were measured continuously and scBRS was assessed by spectrum and sequence methodologies. scBRS was reduced with hypoxia (P < 0.01). Using the spectrum analysis approach, the fall in scBRS with hypoxia was attenuated with infusion of low-dose dopamine (P < 0.01). The decrease in baroreflex sensitivity to rising pressures (scBRS "up-up") was also attenuated with low-dose dopamine (P < 0.05). However, dopamine did not attenuate the decrease in baroreflex sensitivity to falling pressures (scBRS "down-down"; P > 0.05). Present findings are consistent with a reduction in scBRS with systemic hypoxia. Furthermore, we show this effect is partially mediated by the carotid body chemoreceptors, given the fall in scBRS is attenuated when activity of the chemoreceptors is reduced with low-dose dopamine. However, the improvement in scBRS with dopamine appears to be specific to rising blood pressures. These results may have important implications for impairments in baroreflex function common in disease states of acute and/or chronic hypoxemia, as well as the experimental use of dopamine to assess such changes.

  3. Effects of CT dose and nodule characteristics on lung-nodule detectability in a cohort of 90 national lung screening trial patients

    NASA Astrophysics Data System (ADS)

    Young, Stefano; Lo, Pechin; Hoffman, John M.; Kim, H. J. Grace; Brown, Matthew S.; McNitt-Gray, Michael F.

    2016-03-01

    Lung cancer screening CT is already performed at low dose. There are many techniques to reduce the dose even further, but it is not clear how such techniques will affect nodule detectability. In this work, we used an in-house CAD algorithm to evaluate detectability. 90348 patients and their raw CT data files were drawn from the National Lung Screening Trial (NLST) database. All scans were acquired at ~2 mGy CTDIvol with fixed tube current, 1 mm slice thickness, and B50 reconstruction kernel on a Sensation 64 scanner (Siemens Healthcare). We used the raw CT data to simulate two additional reduced-dose scans for each patient corresponding to 1 mGy (50%) and 0.5 mGy (25%). Radiologists' findings on the NLST reader forms indicated 65 nodules in the cohort, which we subdivided based on LungRADS criteria. For larger category 4 nodules, median sensitivities were 100% at all three dose levels, and mean sensitivity decreased with dose. For smaller nodules meeting the category 2 or 3 criteria, the dose dependence was less obvious. Overall, mean patient-level sensitivity varied from 38.5% at 100% dose to 40.4% at 50% dose, a difference of only 1.9%. However, the false-positive rate quadrupled from 1 per case at 100% dose to 4 per case at 25% dose. Dose reduction affected lung-nodule detectability differently depending on the LungRADS category, and the false-positive rate was very sensitive at sub-screening dose levels. Thus, care should be taken to adapt CAD for the very challenging noise characteristics of screening.

  4. Secondary neutron doses received by paediatric patients during intracranial proton therapy treatments.

    PubMed

    Sayah, R; Farah, J; Donadille, L; Hérault, J; Delacroix, S; De Marzi, L; De Oliveira, A; Vabre, I; Stichelbaut, F; Lee, C; Bolch, W E; Clairand, I

    2014-06-01

    This paper's goal is to assess secondary neutron doses received by paediatric patients treated for intracranial tumours using a 178 MeV proton beam. The MCNPX Monte Carlo model of the proton therapy facility, previously validated through experimental measurements for both proton and neutron dosimetry, was used. First, absorbed dose was calculated for organs located outside the clinical target volume using a series of hybrid computational phantoms for different ages and considering a realistic treatment plan. In general, secondary neutron dose was found to decrease as the distance to the treatment field increases and as the patient age increases. In addition, secondary neutron doses were studied as a function of the beam incidence. Next, neutron equivalent dose was assessed using organ-specific energy-dependent radiation weighting factors determined from Monte Carlo simulations of neutron spectra at each organ. The equivalent dose was found to reach a maximum value of ∼155 mSv at the level of the breasts for a delivery of 49 proton Gy to an intracranial tumour of a one-year-old female patient. Finally, a thorough comparison of the calculation results with published data demonstrated the dependence of neutron dose on the treatment configuration and proved the need for facility-specific and treatment-dependent neutron dose calculations.

  5. Active Breathing Coordinator Reduces Radiation Dose to the Heart and Preserves Local Control in Patients with Left Breast Cancer: Report of a Prospective Trial

    PubMed Central

    Eldredge-Hindy, Harriet; Lockamy, Virginia; Crawford, Albert; Nettleton, Virginia; Werner-Wasik, Maria; Siglin, Joshua; Simone, Nicole L.; Sidhu, Kulbir; Anne, Pramila R.

    2014-01-01

    Purpose Incidental radiation dose to the heart and lung during breast radiotherapy (RT) has been associated with an increased risk of cardiopulmonary morbidity. We conducted a prospective trial to determine if RT with the Active Breathing Coordinator (ABC) can reduce the mean heart dose (MHD) by ≥20% and dose to the lung. Methods & Materials Patients with Stages 0-III left breast cancer (LBC) were enrolled and underwent simulation with both free breathing (FB) and ABC for comparison of dosimetry. ABC was used during the patient’s RT course if the MHD was reduced by ≥5%. The median prescription dose was 50.4 Gy plus a boost in 77 patients (90%). The primary endpoint was the magnitude of MHD reduction when comparing ABC to FB. Secondary endpoints included dose reduction to the heart and lung, procedural success rate, and adverse events. Results 112 pts with LBC were enrolled from 2002 to 2011 and 86 eligible patients underwent both FB and ABC simulation. Ultimately, 81 pts received RT using ABC, corresponding to 72% procedural success. The primary endpoint was achieved as use of ABC reduced MHD by 20% or greater in 88% of patients (p<0.0001). The median values for absolute and relative reduction in MHD were 1.7 Gy and 62%, respectively. RT with ABC provided a statistically significant dose reduction to the left lung. After a median follow up of 81 mos., 8-year estimates of locoregional relapse, disease-free, and overall survival were 7%, 90%, and 96%, respectively. Conclusions ABC was well tolerated and significantly reduced MHD while preserving local control. Use of the ABC device during RT should be considered to reduce the risk of ischemic heart disease in populations at risk. PMID:25567159

  6. Design and functionalities of the MADOR® software suite for dose-reduction management after DTPA therapy.

    PubMed

    Leprince, B; Fritsch, P; Bérard, P; Roméo, P-H

    2016-03-01

    A software suite on biokinetics of radionuclides and internal dosimetry intended for the occupational health practitioners of nuclear industry and for expert opinions has been developed under Borland C++ Builder™. These computing tools allow physicians to improve the dosimetric follow-up of workers in agreement with the French regulations and to manage new internal contaminations by radionuclides such as Pu and/or Am after diethylene triamine penta-acetic acid treatments. In this paper, the concept and functionalities of the first two computing tools of this MADOR(®) suite are described. The release 0.0 is the forensic application, which allows calculating the derived recording levels for intake by inhalation or ingestion of the main radioisotopes encountered in occupational environment. Indeed, these reference values of activity are convenient to interpret rapidly the bioassay measurements and make decisions as part of medical monitoring. The release 1.0 addresses the effect of DTPA treatments on Pu/Am biokinetics and the dose benefit. The forensic results of the MADOR(®) suite were validated by comparison with reference data.

  7. Toward a dose reduction strategy using model-based reconstruction with limited-angle tomosynthesis

    NASA Astrophysics Data System (ADS)

    Haneda, Eri; Tkaczyk, J. E.; Palma, Giovanni; Iordache, Rǎzvan; Zelakiewicz, Scott; Muller, Serge; De Man, Bruno

    2014-03-01

    Model-based iterative reconstruction (MBIR) is an emerging technique for several imaging modalities and appli- cations including medical CT, security CT, PET, and microscopy. Its success derives from an ability to preserve image resolution and perceived diagnostic quality under impressively reduced signal level. MBIR typically uses a cost optimization framework that models system geometry, photon statistics, and prior knowledge of the recon- structed volume. The challenge of tomosynthetic geometries is that the inverse problem becomes more ill-posed due to the limited angles, meaning the volumetric image solution is not uniquely determined by the incom- pletely sampled projection data. Furthermore, low signal level conditions introduce additional challenges due to noise. A fundamental strength of MBIR for limited-views and limited-angle is that it provides a framework for constraining the solution consistent with prior knowledge of expected image characteristics. In this study, we analyze through simulation the capability of MBIR with respect to prior modeling components for limited-views, limited-angle digital breast tomosynthesis (DBT) under low dose conditions. A comparison to ground truth phantoms shows that MBIR with regularization achieves a higher level of fidelity and lower level of blurring and streaking artifacts compared to other state of the art iterative reconstructions, especially for high contrast objects. The benefit of contrast preservation along with less artifacts may lead to detectability improvement of microcalcification for more accurate cancer diagnosis.

  8. VMAT QA: Measurement-guided 4D dose reconstruction on a patient

    SciTech Connect

    Nelms, Benjamin E.; Opp, Daniel; Robinson, Joshua; Wolf, Theresa K.; Zhang, Geoffrey; Moros, Eduardo; Feygelman, Vladimir

    2012-07-15

    Purpose: To develop and validate a volume-modulated arc therapy (VMAT) quality assurance (QA) tool that takes as input a time-resolved, low-density ({approx}10 mm) cylindrical surface dose map from a commercial helical diode array, and outputs a high density, volumetric, time-resolved dose matrix on an arbitrary patient dataset. This first validation study is limited to a homogeneous 'patient.'Methods: A VMAT treatment is delivered to a diode array phantom (ARCCHECK, Sun Nuclear Corp., Melbourne, FL). 3DVH software (Sun Nuclear) derives the high-density volumetric dose using measurement-guided dose reconstruction (MGDR). MGDR cylindrical phantom results are then used to perturb the three-dimensional (3D) treatment planning dose on the patient dataset, producing a semiempirical volumetric dose grid. Four-dimensional (4D) dose reconstruction on the patient is also possible by morphing individual sub-beam doses instead of the composite. For conventional (3D) dose comparison two methods were developed, using the four plans (Multi-Target, C-shape, Mock Prostate, and Head and Neck), including their structures and objectives, from the AAPM TG-119 report. First, 3DVH and treatment planning system (TPS) cumulative point doses were compared to ion chamber in a cube water-equivalent phantom ('patient'). The shape of the phantom is different from the ARCCHECK and furthermore the targets were placed asymmetrically. Second, coronal and sagittal absolute film dose distributions in the cube were compared with 3DVH and TPS. For time-resolved (4D) comparisons, three tests were performed. First, volumetric dose differences were calculated between the 3D MGDR and cumulative time-resolved patient (4D MGDR) dose at the end of delivery, where they ideally should be identical. Second, time-resolved (10 Hz sampling rate) ion chamber doses were compared to cumulative point dose vs time curves from 4D MGDR. Finally, accelerator output was varied to assess the linearity of the 4D MGDR with

  9. X-ray tube current modulation and patient doses in chest CT.

    PubMed

    He, Wenjun; Huda, Walter; Magill, Dennise; Tavrides, Emily; Yao, Hai

    2011-01-01

    The aim of the study was to investigate how patient effective doses vary as a function of X-ray tube projection angle, as well as the patient long axis, and quantify how X-ray tube current modulation affects patient doses in chest CT examinations. Chest examinations were simulated for a gantry CT scanner geometry with projections acquired for a beam width of 4 cm. PCXMC 2.0.1 was used to calculate patient effective doses at 15° intervals around the patient's isocentre, and at nine locations along the patient long axis. Idealised tube current modulation schemes were modelled as a function of the X-ray tube angle and the patient long axis. Tube current modulations were characterised by the modulation amplitude R, which was allowed to vary between 1.5 and 5. Effective dose maxima occur for anteroposterior projections at the location of the (radiosensitive) breasts. The maximum to minimum ratio of effective doses as a function of the patient long axis was 4.9, and as a function of the X-ray tube angle was 2.1. Doubling the value of R reduces effective doses from longitudinal modulation alone by ∼4% and from angular modulation alone by ∼2%. In chest CT, tube current modulation schemes currently have longitudinal R values of ∼2.2, and angular R values that range between 1.5 and 3.4. Current X-ray tube current modulation schemes are expected to reduce patient effective doses in chest CT examinations by ∼10%, with longitudinal modulation accounting for two-thirds and angular modulation for the remaining one-third.

  10. An internal radiation dosimetry computer program, IDAC 2.0, for estimation of patient doses from radiopharmaceuticals.

    PubMed

    Andersson, M; Johansson, L; Minarik, D; Mattsson, S; Leide-Svegborn, S

    2014-12-01

    The internal dosimetry computer program internal dose assessment by computer (IDAC) for calculations of absorbed doses to organs and tissues as well as effective doses to patients from examinations with radiopharmaceuticals has been developed. The new version, IDAC2.0, incorporates the International Commission on Radiation Protection (ICRP)/ICRU computational adult male and female voxel phantoms and decay data from the ICRP publication 107. Instead of only 25 source and target regions, calculation can now be made with 63 source regions to 73 target regions. The major advantage of having the new phantom is that the calculations of the effective doses can be made with the latest tissue weighting factors of ICRP publication 103. IDAC2.0 uses the ICRP human alimentary tract (HAT) model for orally administrated activity and for excretion through the gastrointestinal tract and effective doses have been recalculated for radiopharmaceuticals that are orally administered. The results of the program are consistent with published data using the same specific absorption fractions and also compared with published data from the same computational phantoms but with segmentation of organs leading to another set of specific absorption fractions. The effective dose is recalculated for all the 34 radiopharmaceuticals that are administered orally and has been published by the ICRP. Using the new HAT model, new tissue weighting factors and the new adult computational voxel phantoms lead to an average effective dose of half of its earlier estimated value. The reduction mainly depends on electron transport simulations to walled organs and the transition from the stylised phantom with unrealistic interorgan distances to more realistic voxel phantoms.

  11. Estimating Radiation Dose Metrics for Patients Undergoing Tube Current Modulation CT Scans

    NASA Astrophysics Data System (ADS)

    McMillan, Kyle Lorin

    Computed tomography (CT) has long been a powerful tool in the diagnosis of disease, identification of tumors and guidance of interventional procedures. With CT examinations comes the concern of radiation exposure and the associated risks. In order to properly understand those risks on a patient-specific level, organ dose must be quantified for each CT scan. Some of the most widely used organ dose estimates are derived from fixed tube current (FTC) scans of a standard sized idealized patient model. However, in current clinical practice, patient size varies from neonates weighing just a few kg to morbidly obese patients weighing over 200 kg, and nearly all CT exams are performed with tube current modulation (TCM), a scanning technique that adjusts scanner output according to changes in patient attenuation. Methods to account for TCM in CT organ dose estimates have been previously demonstrated, but these methods are limited in scope and/or restricted to idealized TCM profiles that are not based on physical observations and not scanner specific (e.g. don't account for tube limits, scanner-specific effects, etc.). The goal of this work was to develop methods to estimate organ doses to patients undergoing CT scans that take into account both the patient size as well as the effects of TCM. This work started with the development and validation of methods to estimate scanner-specific TCM schemes for any voxelized patient model. An approach was developed to generate estimated TCM schemes that match actual TCM schemes that would have been acquired on the scanner for any patient model. Using this approach, TCM schemes were then generated for a variety of body CT protocols for a set of reference voxelized phantoms for which TCM information does not currently exist. These are whole body patient models representing a variety of sizes, ages and genders that have all radiosensitive organs identified. TCM schemes for these models facilitated Monte Carlo-based estimates of fully

  12. Local Correlation Between Monte-Carlo Dose and Radiation-Induced Fibrosis in Lung Cancer Patients

    SciTech Connect

    Stroian, Gabriela; Martens, Chandra; Souhami, Luis; Collins, D. Louis; Seuntjens, Jan

    2008-03-01

    Purpose: To present a new method of evaluating the correlation between radiotherapy (RT)-induced fibrosis and the local dose delivered to non-small-cell lung cancer patients. Methods and Materials: Treatment plans were generated using the CadPlan treatment planning system (pencil beam, no heterogeneity corrections), and RT delivery was based on these plans. Retrospective Monte-Carlo dose calculations were performed, and the Monte-Carlo distributions of dose to real tissue were calculated using the planning computed tomography (CT) images and the number of monitor units actually delivered. After registration of the follow-up CT images with the planning CT images, different grades of radiologic fibrosis were automatically segmented on the follow-up CT images. Subsequently, patient-specific fibrosis probabilities were studied as a function of the local dose and a function of time after RT completion. Results: A strong patient-specific variation in the fibrosis volumes was found during the follow-up period. For both lungs, the threshold dose for which the probability of fibrosis became significant coincided with the threshold dose at which significant volumes of the lung were exposed. At later stages, only fibrosis localized in the high-dose regions persisted for both lungs. Overall, the Monte-Carlo dose distributions correlated much better with the probability of RT-induced fibrosis than did the CadPlan dose distributions. Conclusion: The presented method allows for an accurate, systematic, patient-specific and post-RT time-dependent numeric study of the relationship between RT-induced fibrosis and the local dose.

  13. Organ doses for reference pediatric and adolescent patients undergoing computed tomography estimated by Monte Carlo simulation

    SciTech Connect

    Lee, Choonsik; Kim, Kwang Pyo; Long, Daniel J.; Bolch, Wesley E.

    2012-04-15

    Purpose: To establish an organ dose database for pediatric and adolescent reference individuals undergoing computed tomography (CT) examinations by using Monte Carlo simulation. The data will permit rapid estimates of organ and effective doses for patients of different age, gender, examination type, and CT scanner model. Methods: The Monte Carlo simulation model of a Siemens Sensation 16 CT scanner previously published was employed as a base CT scanner model. A set of absorbed doses for 33 organs/tissues normalized to the product of 100 mAs and CTDI{sub vol} (mGy/100 mAs mGy) was established by coupling the CT scanner model with age-dependent reference pediatric hybrid phantoms. A series of single axial scans from the top of head to the feet of the phantoms was performed at a slice thickness of 10 mm, and at tube potentials of 80, 100, and 120 kVp. Using the established CTDI{sub vol}- and 100 mAs-normalized dose matrix, organ doses for different pediatric phantoms undergoing head, chest, abdomen-pelvis, and chest-abdomen-pelvis (CAP) scans with the Siemens Sensation 16 scanner were estimated and analyzed. The results were then compared with the values obtained from three independent published methods: CT-Expo software, organ dose for abdominal CT scan derived empirically from patient abdominal circumference, and effective dose per dose-length product (DLP). Results: Organ and effective doses were calculated and normalized to 100 mAs and CTDI{sub vol} for different CT examinations. At the same technical setting, dose to the organs, which were entirely included in the CT beam coverage, were higher by from 40 to 80% for newborn phantoms compared to those of 15-year phantoms. An increase of tube potential from 80 to 120 kVp resulted in 2.5-2.9-fold greater brain dose for head scans. The results from this study were compared with three different published studies and/or techniques. First, organ doses were compared to those given by CT-Expo which revealed dose

  14. Intravenous Iron Therapy in Patients with Iron Deficiency Anemia: Dosing Considerations

    PubMed Central

    Koch, Todd A.; Myers, Jennifer; Goodnough, Lawrence Tim

    2015-01-01

    Objective. To provide clinicians with evidence-based guidance for iron therapy dosing in patients with iron deficiency anemia (IDA), we conducted a study examining the benefits of a higher cumulative dose of intravenous (IV) iron than what is typically administered. Methods. We first individually analyzed 5 clinical studies, averaging the total iron deficit across all patients utilizing a modified Ganzoni formula; we then similarly analyzed 2 larger clinical studies. For the second of the larger studies (Study 7), we also compared the efficacy and retreatment requirements of a cumulative dose of 1500 mg ferric carboxymaltose (FCM) to 1000 mg iron sucrose (IS). Results. The average iron deficit was calculated to be 1531 mg for patients in Studies 1–5 and 1392 mg for patients in Studies 6-7. The percentage of patients who were retreated with IV iron between Days 56 and 90 was significantly (p < 0.001) lower (5.6%) in the 1500 mg group, compared to the 1000 mg group (11.1%). Conclusions. Our data suggests that a total cumulative dose of 1000 mg of IV iron may be insufficient for iron repletion in a majority of patients with IDA and a dose of 1500 mg is closer to the actual iron deficit in these patients. PMID:26257955

  15. SU-E-T-04: 3D Dose Based Patient Compensator QA Procedure for Proton Radiotherapy

    SciTech Connect

    Zou, W; Reyhan, M; Zhang, M; Davis, R; Jabbour, S; Khan, A; Yue, N

    2015-06-15

    Purpose: In proton double-scattering radiotherapy, compensators are the essential patient specific devices to contour the distal dose distribution to the tumor target. Traditional compensator QA is limited to checking the drilled surface profiles against the plan. In our work, a compensator QA process was established that assess the entire compensator including its internal structure for patient 3D dose verification. Methods: The fabricated patient compensators were CT scanned. Through mathematical image processing and geometric transformations, the CT images of the proton compensator were combined with the patient simulation CT images into a new series of CT images, in which the imaged compensator is placed at the planned location along the corresponding beam line. The new CT images were input into the Eclipse treatment planning system. The original plan was calculated to the combined CT image series without the plan compensator. The newly computed patient 3D dose from the combined patientcompensator images was verified against the original plan dose. Test plans include the compensators with defects intentionally created inside the fabricated compensators. Results: The calculated 3D dose with the combined compensator and patient CT images reflects the impact of the fabricated compensator to the patient. For the test cases in which no defects were created, the dose distributions were in agreement between our method and the corresponding original plans. For the compensator with the defects, the purposely changed material and a purposely created internal defect were successfully detected while not possible with just the traditional compensator profiles detection methods. Conclusion: We present here a 3D dose verification process to qualify the fabricated proton double-scattering compensator. Such compensator detection process assesses the patient 3D impact of the fabricated compensator surface profile as well as the compensator internal material and structure changes

  16. Comparison of effective radiation doses from X-ray, CT, and PET/CT in pediatric patients with neuroblastoma using a dose monitoring program

    PubMed Central

    Kim, Yeun Yoon; Shin, Hyun Joo; Kim, Myung-Joon; Lee, Mi-Jung

    2016-01-01

    PURPOSE We aimed to evaluate the use of a dose monitoring program for calculating and comparing the diagnostic radiation doses in pediatric patients with neuroblastoma. METHODS We retrospectively reviewed diagnostic and therapeutic imaging studies performed on pediatric patients with neuroblastoma from 2003 to 2014. We calculated the mean effective dose per exam for X-ray, conventional computed tomography (CT), and CT of positron emission tomography/computed tomography (PET/CT) from the data collected using a dose monitoring program (DoseTrack group) since October 2012. Using the data, we estimated the cumulative dose per person and the relative dose from each modality in all patients (Total group). The effective dose from PET was manually calculated for all patients. RESULTS We included 63 patients with a mean age of 3.2±3.5 years; 28 had a history of radiation therapy, with a mean irradiated dose of 31.9±23.2 Gy. The mean effective dose per exam was 0.04±0.19 mSv for X-ray, 1.09±1.11 mSv for CT, and 8.35±7.45 mSv for CT of PET/CT in 31 patients of the Dose-Track group. The mean estimated cumulative dose per patient in the Total group was 3.43±2.86 mSv from X-ray (8.5%), 7.66±6.09 mSv from CT (19.1%), 18.35±13.52 mSv from CT of PET/CT (45.7%), and 10.71±10.05 mSv from PET (26.7%). CONCLUSION CT of PET/CT contributed nearly half of the total cumulative dose in pediatric patients with neuroblastoma. The radiation dose from X-ray was not negligible because of the large number of X-ray images. A dose monitoring program can be useful for calculating radiation doses in patients with cancer. PMID:27306659

  17. Patient-specific organ dose estimation during transcatheter arterial embolization using Monte Carlo method and adaptive organ segmentation

    NASA Astrophysics Data System (ADS)

    Tsai, Hui-Yu; Lin, Yung-Chieh; Tyan, Yeu-Sheng

    2014-11-01

    The purpose of this study was to evaluate organ doses for individual patients undergoing interventional transcatheter arterial embolization (TAE) for hepatocellular carcinoma (HCC) using measurement-based Monte Carlo simulation and adaptive organ segmentation. Five patients were enrolled in this study after institutional ethical approval and informed consent. Gafchromic XR-RV3 films were used to measure entrance surface dose to reconstruct the nonuniform fluence distribution field as the input data in the Monte Carlo simulation. XR-RV3 films were used to measure entrance surface doses due to their lower energy dependence compared with that of XR-RV2 films. To calculate organ doses, each patient's three-dimensional dose distribution was incorporated into CT DICOM images with image segmentation using thresholding and k-means clustering. Organ doses for all patients were estimated. Our dose evaluation system not only evaluated entrance surface doses based on measurements, but also evaluated the 3D dose distribution within patients using simulations. When film measurements were unavailable, the peak skin dose (between 0.68 and 0.82 of a fraction of the cumulative dose) can be calculated from the cumulative dose obtained from TAE dose reports. Successful implementation of this dose evaluation system will aid radiologists and technologists in determining the actual dose distributions within patients undergoing TAE.

  18. SU-F-18C-12: On the Relationship of the Weighted Dose to the Surface Dose In Abdominal CT - Patient Size Dependency

    SciTech Connect

    Zhou, Y; Scott, A; Allahverdian, J

    2014-06-15

    Purpose: It is possible to measure the patient surface dose non-invasively using radiolucent dosimeters. However, the patient size specific weighted dose remains unknown. We attempted to study the weighted dose to surface dose relationship as the patient size varies in abdominal CT. Methods: Seven abdomen phantoms (CIRS TE series) simulating patients from an infant to a large adult were used. Size specific doses were measured with a 100 mm CT chamber under axial scans using a Siemens Sensation 64 (mCT) and a GE 750 HD. The scanner settings were 120 kVp, 200 mAs with fully opened collimations. Additional kVps (80, 100, 140) were added depending on the phantom sizes. The ratios (r) of the weighted CT dose (Dw) to the surface dose (Ds) were related to the phantom size (L) defined as the diameter resulting the equivalent cross-sectional area. Results: The Dw versus Ds ratio (r) was fitted to a linear relationship: r = 1.083 − 0.007L (R square = 0.995), and r = 1.064 − 0.007L (R square = 0.953), for Siemens Sensation 64 and GE 750 HD, respectively. The relationship appears to be independent of the scanner specifics. Conclusion: The surface dose to the weighted dose ratio decreases linearly as the patient size increases. The result is independent of the scanner specifics. The result can be used to obtain in vivo CT dosimetry in abdominal CT.

  19. Age influences initial dose and compliance to imatinib in chronic myeloid leukemia elderly patients but concomitant comorbidities appear to influence overall and event-free survival.

    PubMed

    Breccia, Massimo; Luciano, Luigiana; Latagliata, Roberto; Castagnetti, Fausto; Ferrero, Dario; Cavazzini, Francesco; Trawinska, Malgorzata Monica; Annunziata, Mario; Stagno, Fabio; Tiribelli, Mario; Binotto, Gianni; Crisà, Elena; Musto, Pellegrino; Gozzini, Antonella; Cavalli, Laura; Montefusco, Enrico; Iurlo, Alessandra; Russo, Sabina; Cedrone, Michele; Rossi, Antonella Russo; Pregno, Patrizia; Endri, Mauro; Spadea, Antonio; Molica, Matteo; Giglio, Gianfranco; Celesti, Francesca; Sorà, Federica; Storti, Sergio; D'Addosio, Ada; Cambrin, Giovanna Rege; Isidori, Alessandro; Sica, Simona; Abruzzese, Elisabetta; Speccha, Giorgina; Rosti, Gianantonio; Alimena, Giuliana

    2014-10-01

    We applied Charlson comorbidity index (CCI) stratification on a large cohort of chronic myeloid leukemia (CML) very elderly patients (>75 years) treated with imatinib, in order to observe the impact of concomitant diseases on both compliance and outcome. One hundred and eighty-one patients were recruited by 21 Italian centers. There were 95 males and 86 females, median age 78.6 years (range 75-93.6). According to Sokal score, 106 patients were classified as intermediate risk and 55 as high risk (not available in 20 patients). According to CCI stratification, 71 patients had score 0 and 110 a score ≥ 1. Imatinib standard dose was reduced at start of therapy (200-300 mg/day) in 68 patients independently from the evaluation of baseline comorbidities, but based only on physician judgement: 43.6% of these patients had score 0 compared to 34% of patients who had score ≥ 1. Significant differences were found in terms of subsequent dose reduction (39% of patients with score 0 compared to 53% of patients with score ≥ 1) and in terms of drug discontinuation due to toxicity (35% of patients with score 0 vs 65% of patients with score ≥ 1). We did not find significant differences as regards occurrence of hematologic side effects, probably as a consequence of the initial dose reduction: 39% of patients with score 0 experienced grade 3/4 hematologic toxicity (most commonly anemia) compared to 42% of patients with score ≥ 1. Independently from the initial dose, comorbidities again did not have an impact on development of grade 3/4 non-hematologic side effects (most commonly skin rash, muscle cramps and fluid retention): 62% of patients with score 0 compared to 52.5% of patients with score ≥ 1. Notwithstanding the reduced dose and the weight of comorbidities we did not find significant differences but only a trend in terms of efficacy: 66% of patients with score 0 achieved a CCyR compared to 54% of patients with score ≥ 1. Comorbidities appeared to have an impact on

  20. Patient radiation dose in prospectively gated axial CT coronary angiography and retrospectively gated helical technique with a 320-detector row CT scanner

    SciTech Connect

    Seguchi, Shigenobu; Aoyama, Takahiko; Koyama, Shuji; Fujii, Keisuke; Yamauchi-Kawaura, Chiyo

    2010-11-15

    Purpose: The aim of this study was to evaluate radiation dose to patients undergoing computed tomography coronary angiography (CTCA) for prospectively gated axial (PGA) technique and retrospectively gated helical (RGH) technique. Methods: Radiation doses were measured for a 320-detector row CT scanner (Toshiba Aquilion ONE) using small sized silicon-photodiode dosimeters, which were implanted at various tissue and organ positions within an anthropomorphic phantom for a standard Japanese adult male. Output signals from photodiode dosimeters were read out on a personal computer, from which organ and effective doses were computed according to guidelines published in the International Commission on Radiological Protection Publication 103. Results: Organs that received high doses were breast, followed by lung, esophagus, and liver. Breast doses obtained with PGA technique and a phase window width of 16% at a simulated heart rate of 60 beats per minute were 13 mGy compared to 53 mGy with RGH technique using electrocardiographically dependent dose modulation at the same phase window width as that in PGA technique. Effective doses obtained in this case were 4.7 and 20 mSv for the PGA and RGH techniques, respectively. Conversion factors of dose length product to the effective dose in PGA and RGH were 0.022 and 0.025 mSv mGy{sup -1} cm{sup -1} with a scan length of 140 mm. Conclusions: CTCA performed with PGA technique provided a substantial effective dose reduction, i.e., 70%-76%, compared to RGH technique using the dose modulation at the same phase windows as those in PGA technique. Though radiation doses in CTCA with RGH technique were the same level as, or some higher than, those in conventional coronary angiography (CCA), the use of PGA technique reduced organ and effective doses to levels less than CCA except for breast dose.

  1. Consolidation Radiotherapy in Primary Central Nervous System Lymphomas: Impact on Outcome of Different Fields and Doses in Patients in Complete Remission After Upfront Chemotherapy

    SciTech Connect

    Ferreri, Andres Jose Maria; Verona, Chiara; Politi, Letterio Salvatore; Chiara, Anna; Perna, Lucia; Villa, Eugenio; Reni, Michele

    2011-05-01

    Purpose: Avoidance radiotherapy or reduction of irradiation doses in patients with primary central nervous system lymphoma (PCNSL) in complete remission (CR) after high-dose methotrexate (HD-MTX)-based chemotherapy has been proposed to minimize the neurotoxicity risk. Nevertheless, no study has focused on the survival impact of radiation parameters, as far as we know, and the optimal radiation schedule remains to be defined. Methods and Materials: The impact on outcome and neurologic performance of different radiation fields and doses was assessed in 33 patients with PCNSL who achieved CR after MTX-containing chemotherapy and were referred to consolidation whole-brain irradiation (WBRT). Patterns of relapse were analyzed on computed tomography-guided treatment planning, and neurologic impairment was assessed by the Mini Mental Status Examination. Results: At a median follow-up of 50 months, 21 patients are relapse-free (5-year failure-free survival [FFS], 51%). WBRT doses {>=}40 Gy were not associated with improved disease control in comparison with a WBRT dose of 30 to 36 Gy (relapse rate, 46% vs. 30%; 5-year FFS, 51% vs. 50%; p = 0.26). Disease control was not significantly different between patients irradiated to the tumor bed with 45 to 54 Gy or with 36 to 44 Gy, with a 5-year FFS of 35% and 44% (p = 0.43), respectively. Twenty patients are alive (5-year overall survival, 54%); WB and tumor bed doses did not have an impact on survival. Impairment as assessed by the Mini Mental Status Examination was significantly more common in patients treated with a WBRT dose {>=}40 Gy. Conclusion: Consolidation with WBRT 36 Gy is advisable in patients with PCNSL in CR after HD-MTX-based chemotherapy. Higher doses do not change the outcome and could increase the risk of neurotoxicity.

  2. Cone beam CT dose reduction in prostate radiotherapy using Likert scale methods

    PubMed Central

    Newton, Louise A; Jordan, Suzanne; Smith, Ruth

    2016-01-01

    Objective: To use a Likert scale method to optimize image quality (IQ) for cone beam CT (CBCT) soft-tissue matching for image-guided radiotherapy of the prostate. Methods: 23 males with local/locally advanced prostate cancer had the CBCT IQ assessed using a 4-point Likert scale (4 = excellent, no artefacts; 3 = good, few artefacts; 2 = poor, just able to match; 1 = unsatisfactory, not able to match) at three levels of exposure. The lateral separations of the subjects were also measured. The Friedman test and Wilcoxon signed-rank tests were used to determine if the IQ was associated with the exposure level. We used the point-biserial correlation and a χ2 test to investigate the relationship between the separation and IQ. Results: The Friedman test showed that the IQ was related to exposure (p = 2 × 10−7) and the Wilcoxon signed-rank test demonstrated that the IQ decreased as exposure decreased (all p-values <0.005). We did not find a correlation between the IQ and the separation (correlation coefficient 0.045), but for separations <35 cm, it was possible to use the lowest exposure parameters studied. Conclusion: We can reduce exposure factors to 80% of those supplied with the system without hindering the matching process for all patients. For patients with lateral separations <35 cm, the exposure factors can be reduced further to 64% of the original values. Advances in knowledge: Likert scales are a useful tool for measuring IQ in the optimization of CBCT IQ for soft-tissue matching in radiotherapy image guidance applications. PMID:26689092

  3. Dose coefficients in pediatric and adult abdominopelvic CT based on 100 patient models

    NASA Astrophysics Data System (ADS)

    Tian, Xiaoyu; Li, Xiang; Segars, W. Paul; Frush, Donald P.; Paulson, Erik K.; Samei, Ehsan

    2013-12-01

    Recent studies have shown the feasibility of estimating patient dose from a CT exam using CTDIvol-normalized-organ dose (denoted as h), DLP-normalized-effective dose (denoted as k), and DLP-normalized-risk index (denoted as q). However, previous studies were limited to a small number of phantom models. The purpose of this work was to provide dose coefficients (h, k, and q) across a large number of computational models covering a broad range of patient anatomy, age, size percentile, and gender. The study consisted of 100 patient computer models (age range, 0 to 78 y.o.; weight range, 2-180 kg) including 42 pediatric models (age range, 0 to 16 y.o.; weight range, 2-80 kg) and 58 adult models (age range, 18 to 78 y.o.; weight range, 57-180 kg). Multi-detector array CT scanners from two commercial manufacturers (LightSpeed VCT, GE Healthcare; SOMATOM Definition Flash, Siemens Healthcare) were included. A previously-validated Monte Carlo program was used to simulate organ dose for each patient model and each scanner, from which h, k, and q were derived. The relationships between h, k, and q and patient characteristics (size, age, and gender) were ascertained. The differences in conversion coefficients across the scanners were further characterized. CTDIvol-normalized-organ dose (h) showed an exponential decrease with increasing patient size. For organs within the image coverage, the average differences of h across scanners were less than 15%. That value increased to 29% for organs on the periphery or outside the image coverage, and to 8% for distributed organs, respectively. The DLP-normalized-effective dose (k) decreased exponentially with increasing patient size. For a given gender, the DLP-normalized-risk index (q) showed an exponential decrease with both increasing patient size and patient age. The average differences in k and q across scanners were 8% and 10%, respectively. This study demonstrated that the knowledge of patient information and CTDIvol/DLP values may

  4. Epidural dexamethasone for post-operative analgesia in patients undergoing abdominal hysterectomy: A dose ranging and safety evaluation study

    PubMed Central

    Hefni, Amira Fathy; Mahmoud, Mohamed Sidky; Al Alim, Azza Atef Abd

    2014-01-01

    Aim: Number of studies revealed that epidural bupivacaine-dexamethasone has the same analgesic potency as bupivacaine-fentanyl with opioid sparing and antiemetic effects. Different doses of dexamethasone were used in different studies. This study was designed to evaluate the optimum dose of epidural dexamethasone for post-operative analgesia. Materials and Methods: In this double-blinded randomized controlled study, we evaluated the efficiency and safety of different doses of epidural dexamethasone for post-operative analgesia in 160 patients aged 45-60 years scheduled for total abdominal hysterectomy. Patient were randomly allocated into four groups to receive a total volume of 10 ml epidural plain bupivacaine 0.25% in the control group (Group D0) with either 4 mg dexamethasone in (Group D4) or 6 mg dexamethasone in (Group D6) or 8 mg dexamethasone in (Group D8). Patients then received general anesthesia. Sedation, satisfaction and visual analog pain scores (VAS) at rest and with effort were measured post-operatively. Meperidine was administered when VAS > or = 4. Intra-operative fentanyl dose, post-operative meperidine consumption and the time to first analgesic requirement were recorded by a blinded observer. Blood glucose was measured pre-operatively and at 4 h and 8 h after study drug administration. Wound healing and infection were assessed after 1 week. Results: Intraoperative fentanyl requirements were comparable among groups. The time to first analgesic requirement was significantly prolonged 5.5 times in D8 Group but only 1.5 times in D6 and D4 Groups more than the analgesic duration in the control Group D0, with a P < 0.01. There was a significant reduction in post-operative meperidine consumption during the first 24 h in the D8 (75%) in comparison with D6 and D4 Groups (50%), respectively, (P < 0.01) and the control Group D0 (0%) (P < 0.01). VAS scores were significantly lower and patient satisfaction score was significantly higher in the D8 and

  5. Estimation of doses to personnel and patients during endovascular brachytherapy applications.

    PubMed

    Kirisits, Christian; Hefner, Alfred; Wexberg, Paul; Pokrajac, Boris; Glogar, Dietmar; Pötter, Richard; Georg, Dietmar

    2004-01-01

    In the last few years coronary endovascular brachytherapy using gamma- and beta-emitting radionuclides has been established as a standard treatment procedure to prevent restenosis after percutaneous coronary interventions. Direct measurements and calculations were made to determine personnel doses and organ doses of patients due to gamma rays of 192Ir and beta rays of 90Sr/90Y and 32P sources. In general, our results show that the dose levels are low compared with the X-ray exposure from angiography. The dose rate from bremsstrahlung at 1 m distance from a device containing a 90Sr/90Y source of 2.3 GBq is 4 micro Sv h(-1). The skin dose from beta rays during source transfer into and from the patient was estimated with the directional dose equivalent H'(0.07) of 10 micro Sv at 1 m distance from the catheter. By maintaining safe distances, the dose levels can be kept well within annual dose limits.

  6. Patient dose, gray level and exposure index with a computed radiography system

    NASA Astrophysics Data System (ADS)

    Silva, T. R.; Yoshimura, E. M.

    2014-02-01

    Computed radiography (CR) is gradually replacing conventional screen-film system in Brazil. To assess image quality, manufactures provide the calculation of an exposure index through the acquisition software of the CR system. The objective of this study is to verify if the CR image can be used as an evaluator of patient absorbed dose too, through a relationship between the entrance skin dose and the exposure index or the gray level values obtained in the image. The CR system used for this study (Agfa model 30-X with NX acquisition software) calculates an exposure index called Log of the Median (lgM), related to the absorbed dose to the IP. The lgM value depends on the average gray level (called Scan Average Level (SAL)) of the segmented pixel value histogram of the whole image. A Rando male phantom was used to simulate a human body (chest and head), and was irradiated with an X-ray equipment, using usual radiologic techniques for chest exams. Thermoluminescent dosimeters (LiF, TLD100) were used to evaluate entrance skin dose and exit dose. The results showed a logarithm relation between entrance dose and SAL in the image center, regardless of the beam filtration. The exposure index varies linearly with the entrance dose, but the angular coefficient is beam quality dependent. We conclude that, with an adequate calibration, the CR system can be used to evaluate the patient absorbed dose.

  7. Adaptive Iterative Dose Reduction Using Three Dimensional Processing (AIDR3D) Improves Chest CT Image Quality and Reduces Radiation Exposure

    PubMed Central

    Yamashiro, Tsuneo; Miyara, Tetsuhiro; Honda, Osamu; Kamiya, Hisashi; Murata, Kiyoshi; Ohno, Yoshiharu; Tomiyama, Noriyuki; Moriya, Hiroshi; Koyama, Mitsuhiro; Noma, Satoshi; Kamiya, Ayano; Tanaka, Yuko; Murayama, Sadayuki

    2014-01-01

    Objective To assess the advantages of Adaptive Iterative Dose Reduction using Three Dimensional Processing (AIDR3D) for image quality improvement and dose reduction for chest computed tomography (CT). Methods Institutional Review Boards approved this study and informed consent was obtained. Eighty-eight subjects underwent chest CT at five institutions using identical scanners and protocols. During a single visit, each subject was scanned using different tube currents: 240, 120, and 60 mA. Scan data were converted to images using AIDR3D and a conventional reconstruction mode (without AIDR3D). Using a 5-point scale from 1 (non-diagnostic) to 5 (excellent), three blinded observers independently evaluated image quality for three lung zones, four patterns of lung disease (nodule/mass, emphysema, bronchiolitis, and diffuse lung disease), and three mediastinal measurements (small structure visibility, streak artifacts, and shoulder artifacts). Differences in these scores were assessed by Scheffe's test. Results At each tube current, scans using AIDR3D had higher scores than those without AIDR3D, which were significant for lung zones (p<0.0001) and all mediastinal measurements (p<0.01). For lung diseases, significant improvements with AIDR3D were frequently observed at 120 and 60 mA. Scans with AIDR3D at 120 mA had significantly higher scores than those without AIDR3D at 240 mA for lung zones and mediastinal streak artifacts (p<0.0001), and slightly higher or equal scores for all other measurements. Scans with AIDR3D at 60 mA were also judged superior or equivalent to those without AIDR3D at 120 mA. Conclusion For chest CT, AIDR3D provides better image quality and can reduce radiation exposure by 50%. PMID:25153797

  8. Erythropoietin Dose and Mortality in Hemodialysis Patients: Marginal Structural Model to Examine Causality

    PubMed Central

    Streja, Elani; Park, Jongha; Chan, Ting-Yan; Lee, Janet; Soohoo, Melissa; Rhee, Connie M.; Arah, Onyebuchi A.; Kalantar-Zadeh, Kamyar

    2016-01-01

    It has been previously reported that a higher erythropoiesis stimulating agent (ESA) dose in hemodialysis patients is associated with adverse outcomes including mortality; however the causal relationship between ESA and mortality is still hotly debated. We hypothesize ESA dose indeed exhibits a direct linear relationship with mortality in models of association implementing the use of a marginal structural model (MSM), which controls for time-varying confounding and examines causality in the ESA dose-mortality relationship. We conducted a retrospective cohort study of 128 598 adult hemodialysis patients over a 5-year follow-up period to evaluate the association between weekly ESA (epoetin-α) dose and mortality risk. A MSM was used to account for baseline and time-varying covariates especially laboratory measures including hemoglobin level and markers of malnutrition-inflammation status. There was a dose-dependent positive association between weekly epoetin-α doses ≥18 000 U/week and mortality risk. Compared to ESA dose of <6 000 U/week, adjusted odds ratios (95% confidence interval) were 1.02 (0.94–1.10), 1.08 (1.00–1.18), 1.17 (1.06–1.28), 1.27 (1.15–1.41), and 1.52 (1.37–1.69) for ESA dose of 6 000 to <12 000, 12 000 to <18 000, 18 000 to <24 000, 24 000 to <30 000, and ≥30 000 U/week, respectively. High ESA dose may be causally associated with excessive mortality, which is supportive of guidelines which advocate for conservative management of ESA dosing regimen in hemodialysis patients. PMID:27298736

  9. Antibiotic dosing in critically ill patients with septic shock and on continuous renal replacement therapy: can we resolve this problem with pharmacokinetic studies and dosing guidelines?

    PubMed

    Roberts, Jason A; Roberts, Darren M

    2014-06-23

    Dosing antibiotics in critically ill patients to achieve therapeutic concentrations is a significant challenge. The presence of septic shock and prescription of continuous renal replacement therapy introduces further complexities for the clinician. Unfortunately, this is a dilemma encountered daily by intensivists. Although small pharmacokinetic studies are emerging to provide data to help address this problem, the variability in results from these studies is profound. As such, effective antibiotic dosing guidelines for critically ill patients who have septic shock and who receive continuous renal replacement therapy are not available. Dosing flowcharts and therapeutic drug monitoring represent the best available options for clinicians to optimize antibiotic dosing.

  10. Interactive dose shaping part 2: proof of concept study for six prostate patients.

    PubMed

    Ph Kamerling, Cornelis; Ziegenhein, Peter; Sterzing, Florian; Oelfke, Uwe

    2016-03-21

    Recently we introduced interactive dose shaping (IDS) as a new IMRT planning strategy. This planning concept is based on a hierarchical sequence of local dose modification and recovery operations. The purpose of this work is to provide a feasibility study for the IDS planning strategy based on a small set of six prostate patients. The IDS planning paradigm aims to perform interactive local dose adaptations of an IMRT plan without compromising already established valuable dose features in real-time. Various IDS tools were developed in our in-house treatment planning software Dynaplan and were utilized to create IMRT treatment plans for six patients with an adeno-carcinoma of the prostate. The sequenced IDS treatment plans were compared to conventionally optimized clinically approved plans (9 beams, co-planar). For each patient, several IDS plans were created, with different trade-offs between organ sparing and target coverage. The reference dose distributions were imported into Dynaplan. For each patient, the IDS treatment plan with a similar or better trade-off between target coverage and OAR sparing was selected for plan evaluation, guided by a physician. For this initial study we were able to generate treatment plans for prostate geometries in 15-45 min. Individual local dose adaptations could be performed in less than one second. The average differences compared to the reference plans were for the mean dose: 0.0 Gy (boost) and 1.2 Gy (PTV), for D98% : -1.1 Gy and for D2% : 1.1 Gy (both target volumes). The dose-volume quality indicators were well below the Quantec constraints. However, we also observed limitations of our currently implemented approach. Most prominent was an increase of the non-tumor integral dose by 16.4% on average, demonstrating that further developments of our planning strategy are required.

  11. Interactive dose shaping part 2: proof of concept study for six prostate patients

    NASA Astrophysics Data System (ADS)

    Kamerling, Cornelis Ph; Ziegenhein, Peter; Sterzing, Florian; Oelfke, Uwe

    2016-03-01

    Recently we introduced interactive dose shaping (IDS) as a new IMRT planning strategy. This planning concept is based on a hierarchical sequence of local dose modification and recovery operations. The purpose of this work is to provide a feasibility study for the IDS planning strategy based on a small set of six prostate patients. The IDS planning paradigm aims to perform interactive local dose adaptations of an IMRT plan without compromising already established valuable dose features in real-time. Various IDS tools were developed in our in-house treatment planning software Dynaplan and were utilized to create IMRT treatment plans for six patients with an adeno-carcinoma of the prostate. The sequenced IDS treatment plans were compared to conventionally optimized clinically approved plans (9 beams, co-planar). For each patient, several IDS plans were created, with different trade-offs between organ sparing and target coverage. The reference dose distributions were imported into Dynaplan. For each patient, the IDS treatment plan with a similar or better trade-off between target coverage and OAR sparing was selected for plan evaluation, guided by a physician. For this initial study we were able to generate treatment plans for prostate geometries in 15-45 min. Individual local dose adaptations could be performed in less than one second. The average differences compared to the reference plans were for the mean dose: 0.0 Gy (boost) and 1.2 Gy (PTV), for {{D}98%}:-