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Bliden KP, Kundan P, Kraft D, Parekh R, Singh S, Babu AD, Shah AP, Tantry US, Gurbel PA. Utility of VerifyNow to assess the immediate pharmacodynamic response of chewed and swallowed aspirin: comparison with aggregometry. Platelets 2024; 35:2298352. [PMID: 38166614 DOI: 10.1080/09537104.2023.2298352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 12/18/2023] [Indexed: 01/05/2024]
Abstract
VerifyNow (VN) test is a less laborious method to assess pharmacodynamics (PD) compared to light transmittance aggregometry (LTA). VN assay has not been used to study the immediate PD effects of acetylsalicylic acid (ASA). Ten healthy volunteers were randomly assigned to a single 162 or 650 mg dose of chewed and swallowed ASA. Pharmacodynamic and pharmacokinetic measurements were performed at baseline and serially up to 60 min after ASA administration. Onset by VN was 20 ± 7 min with 162 mg and 13 ± 7 min with 650 mg ASA (p = .07). Onset by 1 mM AA-induced PA was 13 ± 12 min with 162 mg and 7 ± 3 min with 650 mg ASA (p=NS). VN correlated with AA-induced PA (r = 0.80, p < .001) and serum TxB2 levels (r = 0.76, p < .001). 95% inhibition of serum TxB2 was achieved at 38 ± 22 min and 22 ± 8 min with the 162 and 650 mg ASA, respectively (p = .08). The onset and extent of the antiplatelet effect of 650 mg ASA is numerically faster and greater than the 162 mg dose. VN identifies the onset, extent, and dose response to ASA therapy. The ease of using VN should facilitate multicenter PD investigations of ASA.
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Affiliation(s)
- Kevin P Bliden
- Sinai Center for Thrombosis Research and Drug Development, Sinai Hospital of Baltimore, Baltimore, MD, USA
| | - Parshotam Kundan
- Sinai Center for Thrombosis Research and Drug Development, Sinai Hospital of Baltimore, Baltimore, MD, USA
| | - Danielle Kraft
- Sinai Center for Thrombosis Research and Drug Development, Sinai Hospital of Baltimore, Baltimore, MD, USA
| | - Rueshil Parekh
- Sinai Center for Thrombosis Research and Drug Development, Sinai Hospital of Baltimore, Baltimore, MD, USA
| | - Sahib Singh
- Sinai Center for Thrombosis Research and Drug Development, Sinai Hospital of Baltimore, Baltimore, MD, USA
| | - Aravind D Babu
- Sinai Center for Thrombosis Research and Drug Development, Sinai Hospital of Baltimore, Baltimore, MD, USA
| | - Anika P Shah
- Sinai Center for Thrombosis Research and Drug Development, Sinai Hospital of Baltimore, Baltimore, MD, USA
| | - Udaya S Tantry
- Sinai Center for Thrombosis Research and Drug Development, Sinai Hospital of Baltimore, Baltimore, MD, USA
| | - Paul A Gurbel
- Sinai Center for Thrombosis Research and Drug Development, Sinai Hospital of Baltimore, Baltimore, MD, USA
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Dowhan GV, Shah AP, Sporer BJ, Jordan NM, Bland SN, Lebedev SV, Smith RA, Suttle L, Pikuz SA, McBride RD. High-magnification Faraday rotation imaging and analysis of X-pinch implosion dynamics. Rev Sci Instrum 2024; 95:043504. [PMID: 38578244 DOI: 10.1063/5.0178321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 03/20/2024] [Indexed: 04/06/2024]
Abstract
An X-pinch load driven by an intense current pulse (>100 kA in ∼100 ns) can result in the formation of a small radius, runaway compressional micro-pinch. A micro-pinch is characterized by a hot (>1 keV), current-driven (>100 kA), high-density plasma column (near solid density) with a small neck diameter (1-10 µm), a short axial extent (<1 mm), and a short duration (≲1 ns). With material pressures often well into the multi-Mbar regime, a micro-pinch plasma often radiates an intense, sub-ns burst of sub-keV to multi-keV x rays. A low-density coronal plasma immediately surrounding the dense plasma neck could potentially shunt current away from the neck and thus reduce the magnetic drive pressure applied to the neck. To study the current distribution in the coronal plasma, a Faraday rotation imaging diagnostic (1064 nm) capable of producing simultaneous high-magnification polarimetric and interferometric images has been developed for the MAIZE facility at the University of Michigan. Designed with a variable magnification (1-10×), this diagnostic achieves a spatial resolution of ∼35 µm, which is useful for resolving the ∼100-μm-scale coronal plasma immediately surrounding the dense core. This system has now been used on a reduced-output MAIZE (100-200 kA, 150 ns) to assess the radial distribution of drive current immediately surrounding the dense micro-pinch neck. The total current enclosed was found to increase as a function of radius, r, from a value of ≈50±25 kA at r ≈ 140 µm (at the edge of the dense neck) to a maximal value of ≈150±75 kA for r ≥ 225 µm. This corresponds to a peak magnetic drive pressure of ≈75±50 kbar at r ≈ 225 µm. The limitations of these measurements are discussed in the paper.
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Affiliation(s)
- G V Dowhan
- Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - A P Shah
- Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - B J Sporer
- Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - N M Jordan
- Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - S N Bland
- Department of Physics, Imperial College London, London SW7 2AZ, United Kingdom
| | - S V Lebedev
- Department of Physics, Imperial College London, London SW7 2AZ, United Kingdom
| | - R A Smith
- Department of Physics, Imperial College London, London SW7 2AZ, United Kingdom
| | - L Suttle
- Department of Physics, Imperial College London, London SW7 2AZ, United Kingdom
| | - S A Pikuz
- Lebedev Physical Institute, Russian Academy of Sciences, Moscow 119991, Russia
| | - R D McBride
- Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109, USA
- Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA
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Horgan R, Nehme L, Jensen HJ, Shah AP, Saal R, Onishi K, Kawakita T, Martins JG, Abuhamad A. Neonatal Outcomes among Fetuses with an Abdominal Circumference <3rd %ile and Estimated Fetal Weight 3rd to 9th %ile Compared to Fetuses with an EFW <3rd %ile. Am J Perinatol 2024. [PMID: 38301725 DOI: 10.1055/a-2259-0148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2024]
Abstract
OBJECTIVE Fetal growth restriction (FGR) is defined as an estimated fetal weight (EFW) or abdominal circumference (AC) <10th percentile (%ile) for gestational age (GA). An EFW <3rd %ile for GA is considered severe FGR (sFGR). It remains unknown if fetuses with isolated AC <3rd %ile should be considered sFGR. Our primary objective was to assess composite neonatal outcomes in fetuses with an AC <3rd %ile and overall EFW 3rd to 9th %ile compared with those with an EFW <3rd %ile. STUDY DESIGN This retrospective cohort study was undertaken at a tertiary academic center from January 2016 to December 2021. Inclusion criteria were singleton fetuses with an EFW <3rd %ile (Group 1) or AC <3rd %ile with EFW 3rd to 9th %ile (Group 2) at 28 weeks' gestation or greater. Exclusion criteria were multiple gestations, presence of a major fetal anomaly, resolution of FGR, genetic syndrome, or infection. Composite neonatal outcome was defined by any of the following: neonatal intensive care unit admission >48 hours, necrotizing enterocolitis, sepsis, respiratory distress syndrome, mechanical ventilation, retinopathy of prematurity, seizures, intraventricular hemorrhage, stillbirth, or death before discharge. Small for gestational age (SGA) was defined as birth weight <10th %ile for GA. RESULTS A total of 743 patients fulfilled our study criteria, with 489 in Group 1 and 254 in Group 2. The composite neonatal outcome occurred in 281 (57.5%) neonates in Group 1 and 53 (20.9%) in Group 2 (p < 0.01). The rates of SGA at birth were 94.9 and 75.6% for Group 1 and Group 2, respectively (OR 5.99, 95% confidence interval 3.65-9.82). CONCLUSION Although AC <3rd %ile with EFW 3rd to 9th %ile is associated with a lower frequency of SGA and neonatal morbidity than EFW <3 %ile, fetuses with AC <3 %ile still exhibited moderate rates of these adverse perinatal outcomes. Consideration should be given to inclusion of an AC <3rd %ile with EFW 3rd to 9th %ile as a criterion for sFGR. However, prospective studies comparing delivery at 37 versus 38 to 39 weeks' gestation are needed to ensure improved outcomes before widespread adaptation in clinical practice. KEY POINTS · The composite neonatal outcome occurred in 57.5% of fetuses with an overall EFW <3rd %ile and 20.9% of fetuses with an AC <3rd %ile but EFW 3rd to 9th %ile.. · Both groups demonstrated a high positive predictive value for SGA birth weight.. · Consideration should be given to inclusion of an AC <3rd %ile as a criterion for sFGR..
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Affiliation(s)
- Rebecca Horgan
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School, Norfolk, Virginia
| | - Lea Nehme
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School, Norfolk, Virginia
| | | | - Anika P Shah
- Eastern Virginia Medical School, Norfolk, Virginia
| | - Ryan Saal
- Eastern Virginia Medical School, Norfolk, Virginia
| | - Kazuma Onishi
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School, Norfolk, Virginia
| | - Tetsuya Kawakita
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School, Norfolk, Virginia
| | - Juliana G Martins
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School, Norfolk, Virginia
| | - Alfred Abuhamad
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School, Norfolk, Virginia
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Gurbel PA, Bliden KP, Kundan P, Kraft D, Parekh R, Singh S, Babu AD, Shah AP, Chaudhary R, Tantry US. Early assessment of the pharmacokinetic and pharmacodynamic effects following acetylsalicylic acid loading: toward a definition for acute therapeutic response. J Thromb Thrombolysis 2024; 57:21-28. [PMID: 38066385 PMCID: PMC10830588 DOI: 10.1007/s11239-023-02914-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/15/2023] [Indexed: 02/01/2024]
Abstract
Despite decades of investigations, the optimal assessment of the "therapeutic response" to early after loading dose of acetylsalicylic acid (ASA) remains unclear. Limited information is available on the relation between pharmacodynamic (PD) and pharmacokinetic (PK) measurements assessed immediately after ASA administration. Serial PD and PK analyses were performed immediately after a single 162 or 650 mg dose of chewed and swallowed ASA in ten healthy adults. ASA response was defined as > 95% inhibition of serum thromboxane (Tx)B2, < 550 aspirin reaction units (ARU) by VerifyNow Aspirin (VN) test, and ≤ 20% arachidonic acid (AA)-induced platelet aggregation (PA). Correlation analyses between PK and PD measurements and receiver operating characteristic (ROC) curve analyses were performed. ASA response measured by VN test and AA-induced PA was achieved within 30 min of ASA administration. A correlation was observed between ARU and AA-induced maximum PA (r = 0.69, p < 0.001), serum TxB2 (r = 0.74 and p < 0.001), and serum TxB2 inhibition (r = 0.79, p < 0.001). In ROC curve analyses, ≤ 558 ARU and ≤ 7% AA-induced PA were associated with > 95% inhibition of TxB2. 686 ng/ml plasma ASA cut-off point was associated with > 95% inhibition of serum TxB2, ≤ 7% 1 mM AA-induced PA, and ≤ 585 ARU. A modest ~ 50% inhibition of TxB2 inhibition was associated with marked inhibition of 1 mM AA-induced platelet aggregation by LTA. Our analyses demonstrated important relationships between pharmacodynamic, and pharmacokinetic parameters measured immediately following oral ASA and cutoff values for ARU and AA-induced PA that is associated with > 95% inhibition of serum TxB2.
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Affiliation(s)
- Paul A Gurbel
- Sinai Center for Thrombosis Research and Drug Development, Sinai Hospital of Baltimore, Baltimore, MD, 21209, USA.
| | - Kevin P Bliden
- Sinai Center for Thrombosis Research and Drug Development, Sinai Hospital of Baltimore, Baltimore, MD, 21209, USA
| | - Parshotam Kundan
- Sinai Center for Thrombosis Research and Drug Development, Sinai Hospital of Baltimore, Baltimore, MD, 21209, USA
| | - Danielle Kraft
- Sinai Center for Thrombosis Research and Drug Development, Sinai Hospital of Baltimore, Baltimore, MD, 21209, USA
| | - Rueshil Parekh
- Sinai Center for Thrombosis Research and Drug Development, Sinai Hospital of Baltimore, Baltimore, MD, 21209, USA
| | - Sahib Singh
- Sinai Center for Thrombosis Research and Drug Development, Sinai Hospital of Baltimore, Baltimore, MD, 21209, USA
| | - Aravind D Babu
- Sinai Center for Thrombosis Research and Drug Development, Sinai Hospital of Baltimore, Baltimore, MD, 21209, USA
| | - Anika P Shah
- Sinai Center for Thrombosis Research and Drug Development, Sinai Hospital of Baltimore, Baltimore, MD, 21209, USA
| | - Rahul Chaudhary
- Heart and Vascular Institute, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
- Artificial Intelligence for Holistic Evaluation and Advancement of Cardiovascular Thrombosis, Pittsburgh, PA, USA
| | - Udaya S Tantry
- Sinai Center for Thrombosis Research and Drug Development, Sinai Hospital of Baltimore, Baltimore, MD, 21209, USA
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Dvorak T, Shah AP, Rineer JM, Kelly P, Dvorak C, Salazar J. Carbon Footprint of Photon Therapy. Int J Radiat Oncol Biol Phys 2023; 117:e579-e580. [PMID: 37785760 DOI: 10.1016/j.ijrobp.2023.06.1919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
PURPOSE/OBJECTIVE(S) Rising carbon dioxide levels have hazardous impact on human health and climate change. This study estimates the energy utilization of radiation therapy and estimates corresponding carbon footprint. MATERIALS/METHODS Patients treated between 07/2020 and 06/2021 using a Varian LINAC system were evaluated. Power draw was directly measured in 1 second increments, from the LINAC machine and the radiation department facility. Patients treated were reviewed for number of fractions and beam duration during each fraction. kWh power consumption was calculated per fraction and per treatment course. Patient commute distance was evaluated using Google Maps. EPA calculator was used to calculate CO2 equivalent (CO2e) footprint. RESULTS There were 176 patients treated for 191 treatment courses. Total of 4,517 fractions were delivered (avg 23.6, range 1 to 48). Average BeamOn time was 141 seconds per fraction (22 to 310 sec); electron plans (n = 8) 29 sec, 2D/3D (n = 63) 77 sec, and IMRT (n = 120) 182 sec. BeamOn power draw was ∼36.3 kW. Power consumption per fraction was 1.4 kWh (0.2 to 3.0 kWh), and per course 37.5 kWh (0.9 to 109.1 kWh). LINAC was otherwise in standby mode 71% of time (∼7.3 kW) and ON/ready mode 25% (∼12.5 kW). Patient BeamOn time accounted for 2% of total its time and 8% of its power use during the year. Incremental standby/ready energy contribution per treatment course was 410 kWh (78,332/191). The building power draw was 12.5 kW, for incremental contribution of 576 kWh per course. Average patient travel distance was 9.6 miles (0.7 miles to 73.5 miles), resulting in 711-mile round trip per course (6 miles to 5620 miles). Corresponding carbon footprint for BeamOn time was 0.6 kg CO2e per fraction (electrons 0.1 kg, 2D/3D 0.3 kg, and IMRT 1.1 kg per fx). The treatment course footprint was 16.2 kg CO2e (0.4 kg to 47.2 kg). The attributed standby/ready LINAC footprint was 177.8 kg CO2e per course. The attributed facility footprint was further 250.0 kg CO2e per course. The attributed commute footprint was further 286.3 kg CO23 per course (2.4 kg to 2264.0 kg). The entire treatment course was 730.4 kg CO2e. As such, single fraction was 0.1% of the total CO2e course (0.01% to 0.27%), BeamOn was 2.3% (0.1% to 7.1%), LINAC standby/ready was 28.0% (6.5% to 41.3%), building was 39.4% (9.2% to 58%), and commute was 30.3% (0.6% to 82.9%). The entire program generated 139.5 metric tons of CO2e during the year. CONCLUSION Linear accelerator BeamOn carbon footprint varied as a function of technique but was only 2% of the overall patient treatment footprint. The LINAC standby electricity contributed 28%, building electricity 39%, and commute 30%, though this varied significantly per patient, as a function of number of fractions and treatment distance. Fixed CO2e contribution from the standby LINAC and the building draw accounted for ∼67% of the footprint. However, radiation oncologists can potentially impact the overall carbon footprint by prescribing fewer fractions to lower total commute, as clinically indicated.
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Affiliation(s)
- T Dvorak
- Department of Radiation Oncology, Orlando Health Cancer Institute, Orlando, FL
| | - A P Shah
- Department of Radiation Oncology, Orlando Health Cancer Institute, Orlando, FL
| | - J M Rineer
- Department of Radiation Oncology, Orlando Health Cancer Institute, Orlando, FL
| | - P Kelly
- Department of Radiation Oncology, Orlando Health Cancer Institute, Orlando, FL
| | - C Dvorak
- Department of Radiation Oncology, Orlando Health Cancer Institute, Orlando, FL
| | - J Salazar
- Department of Radiation Oncology, Orlando Health Cancer Institute, Orlando, FL
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Cabrera J, Kelly P, Rineer JM, Swanick CW, Shah AP, Zeidan OA, Demez N, Erhart K. Defining the Role of Intensity Modulation in Electron Conformal Therapy for the Treatment of Head and Neck Cancer. Int J Radiat Oncol Biol Phys 2023; 117:e646. [PMID: 37785923 DOI: 10.1016/j.ijrobp.2023.06.2063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
PURPOSE/OBJECTIVE(S) The use of bolus electron conformal therapy (BECT) in the treatment of cancers of the head and neck is often limited by an inability to reduce dosimetric hot spots resulting from surface or tissue heterogeneity. In this study, we examined the potential benefits of using a recently patented, low-cost form of Intensity Modulation for electron therapy (IM-BECT) to reduce treatment hotspots in patients undergoing electron beam therapy for cancer of the Head and Neck (HN). MATERIALS/METHODS The treatment plans from twelve patients with HN cancer previously treated with BECT were identified (treatment energies ranged from 6-18 MeV and field sizes of 36-625 cm2). Each case included the treatment targets and at least one primary OAR that were defined by the original treating radiation oncologist. Additionally, a target + 2 cm rind structure was created for analysis of the dose deposition in areas immediately surrounding the target volume as a measure of conformality. Each patient plan was transferred into a novel IM-BECT planning software and each case was recomputed as per the original prescription, gantry, couch, collimator angles, and original clinically used bolus. Next, each case was replanned with the inclusion of intensity modulation, as well as a new custom conformal bolus that was designed for optimized range compensation. The patient plans were then normalized such that 100% equals the prescription dose value and then transferred to a plan analysis software for comparison of the target coverage/dose and OAR dose. RESULTS Comparison of the BECT and IM-BECT treatment plans demonstrated that IM-BECT was able to significantly reduce dosimetric hotspots for this cohort of patients undergoing radiation therapy for HN cancer, bringing the average maximum dose down from 130.6% to only 120.6% (p = 0.044, paired t-test). Moreover, the impact of IM-BECT appeared to be most substantial in the patients with the highest baseline maximum dose. For patients who had a hotspot of 125% or greater, the hotspot was on average reduced by 19%. Further dosimetric analysis demonstrated a small resultant increase in the low dose deposition to the surrounding normal tissues. For BECT, the average primary OAR mean dose and Target+2cm rind mean dose were 27.5% and 60.0%, respectively. For IM-BECT, the average primary OAR mean dose and Target+2cm rind mean dose increased slightly to 30.9% and 64.6%, respectively [Primary OAR mean (P = 0.0008), and Target+2cm rind mean (P = 0.0001), paired t-test]. CONCLUSION IM-BECT is an effective method of reducing dosimetric hotspots in patients undergoing radiation therapy for cancer of the HN. This improvement came at the expense of a small increase in dose to the underlying tissues. This retrospective planning study represents the first example of IM-BECT being applied to real patient cases and suggests further development of IM-BECT is warranted.
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Affiliation(s)
- J Cabrera
- Department of Radiation Oncology, Orlando Health Cancer Institute, Orlando, FL
| | - P Kelly
- Department of Radiation Oncology, Orlando Health Cancer Institute, Orlando, FL
| | - J M Rineer
- Department of Radiation Oncology, Orlando Health Cancer Institute, Orlando, FL
| | - C W Swanick
- Department of Radiation Oncology, Orlando Health Cancer Institute, Orlando, FL
| | - A P Shah
- Department of Radiation Oncology, Orlando Health Cancer Institute, Orlando, FL
| | - O A Zeidan
- Department of Radiation Oncology, Orlando Health Cancer Institute, Orlando, FL
| | - N Demez
- Department of Radiation Oncology, Orlando Health Cancer Institute, Orlando, FL
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Salazar J, Speedy J, Shah AP, Dvorak T. Comparison of the Direct Power Consumption for Different Linac Treatment Parameters in External Beam Radiation Therapy. Int J Radiat Oncol Biol Phys 2023; 117:e621-e622. [PMID: 37785861 DOI: 10.1016/j.ijrobp.2023.06.2006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
PURPOSE/OBJECTIVE(S) The negative impact of climate change on the environment has led to increasing concern around the world. Relatively little is known about the contribution of radiation oncology systems to carbon emissions. This study measures the energy utilization of Linac-based EBRT for different treatment parameters and techniques, which was then converted to power use (kWh) and ultimately a carbon footprint of various photon treatment approaches. MATERIALS/METHODS A Varian TrueBeam was evaluated. The direct power consumption was measured using a Fluke 1736 Power Logger, recorded in one-second intervals for one week. Different photon and electron beam energies, dose rates, treatment techniques (3D, IMRT, gated), and imaging types (kV, MV) were evaluated. Clinical treatment plans were reviewed, and average treatment times used to determine kWh. IRB approval was obtained. The Greenhouse Gas Equivalencies Calculator was used to determine kg of CO2. RESULTS Power draw for 6 MV, 10 MV, and 18 MV at a rep rate of 600 MU/min was 31.6, 32.0, and 27.5 kW, respectively. The power draw for end of range dose rates for 6 MV (60, 600), 6 FFF (400, 1400), 10 FFF (400, 2400), and 6 MeV (100, 1000) were (22.2, 31.6 kW), (23.7, 31.6 kW), (19.6, 32.1 kW), and (22.6, 23.6 kW), respectively. 6 MV open 2D fields, modulated IMRT fields, and gated/beam hold fields had similar power draw at 31.6, 31.7, and 31.9 kW, respectively. Portal MV imaging with 2.5 MV beam was 32.5 kW, while CBCT and kV/kV imaging was ∼11 kW and not distinguishable from baseline power fluctuations. A total of 191 delivered treatment plans were reviewed. Electron plans (n = 8) treatment time was on average 29 sec (16 sec STDEV) per fraction and 635 sec (185 sec STDEV) per course, 2D/3D plans (n = 63) were 77 sec (32 sec STDEV) and 1004 sec (1002 sec STDEV), and IMRT plans (n = 120) were 182 sec (60 sec STDEV) and 5351 sec (2401 sec STDEV), respectively. The kWh per treatment for electron, 2D/3D, and IMRT plans were 0.19, 0.68, and 1.6 kWh, respectively. The CO2 equivalent for electrons, 2D/3D, and IMRT techniques are 0.08, 0.29, and 0.7 kg. CONCLUSION There was some variability in the power draw for different energies and different dose rates but was relatively stable around 32 kW. Power consumption for clinical therapy is a result of kW power draw multiplied by duration of beam delivery, which for our patients varied significantly as a function of technique and number of fractions delivered. Reduction in radiation oncology carbon footprint will likely be driven more by number of fractions and type of treatment technique, and length of patient commute, rather than beam energy and dose rate selection.
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Affiliation(s)
- J Salazar
- Department of Radiation Oncology, Orlando Health Cancer Institute, Orlando, FL
| | | | - A P Shah
- Department of Radiation Oncology, Orlando Health Cancer Institute, Orlando, FL
| | - T Dvorak
- Department of Radiation Oncology, Orlando Health Cancer Institute, Orlando, FL
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Horgan R, Nehme L, Jensen HJ, Shah AP, Saal RC, Onishi K, Kawakita T, Martins JG, Abuhamad A. Should abdominal circumference <3rd percentile be included in the definition of severe fetal growth restriction? Am J Obstet Gynecol 2023. [DOI: 10.1016/j.ajog.2022.11.1213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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9
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Shirkhodaie C, Venturini JM, Shah AP, Nathan S, Paul J, Kalathiya R, Blair JEA. Retrospective comparison of percutaneous balloon pericardiotomy with pericardiocentesis versus pericardiocentesis alone for management of symptomatic pericardial effusions. Eur Heart J 2021. [DOI: 10.1093/eurheartj/ehab724.1831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Background
Cardiac tamponade is a potentially life-threatening complication of pericardial effusion. Pericardiocentesis with drainage is the mainstay of treatment for patients with pericardial effusion and cardiac tamponade. Percutaneous balloon pericardiotomy (PBP) is an adjunct to pericardiocentesis that may alleviate the risk for recurrent effusion and repeat procedures. However, the efficacy of PBP plus pericardiocentesis compared to pericardiocentesis alone is not clear.
Purpose
We sought to determine whether PBP plus pericardiocentesis was associated with less recurrence of pericardial effusion than pericardiocentesis alone.
Methods
We conducted a single-centre retrospective analysis of patients ≥18 years old with non-iatrogenic pericardial effusion undergoing either pericardiocentesis alone or PBP plus pericardiocentesis for the first time. For PBP, a balloon was advanced over a guidewire until it crossed the pericardium and was then inflated until the balloon profile was fully expanded. Type of balloon used, and single or double balloon technique were left up to the operator. Recurrent pericardial effusion was defined as a large pericardial effusion on echocardiogram, pericardial effusion that caused hemodynamic compromise, or pericardial effusion that necessitated another intervention to drain at any time after initial procedure. Risk factors for recurrent pericardial effusion were also assessed.
Results
There were 208 patients who underwent pericardiocentesis, with 33 patients receiving PBP plus pericardiocentesis. In all patients, the rate of recurrent pericardial effusion was 15.9% and 15.2%, respectively (p=0.92). In patients with a cancer diagnosis at time of procedure, the rate of recurrent pericardial effusion was 17.8% and 16.7%, respectively (p=0.89). In patients with malignant pericardial effusion as confirmed by cytology, the rate of recurrent pericardial effusion was 20.4% and 13.3%, respectively (p=0.72). Patients with a connective tissue disease (CTD) had an increased odds ratio (OR) of recurrent pericardial effusion when compared to patients without a CTD (OR 3.19, 95% CI 1.31–7.77).
Conclusions
The results of this study suggest that PBP plus pericardiocentesis offers no significant benefit over pericardiocentesis alone at preventing recurrent pericardial effusion. This finding was true in all sub-groups, including patients with cancer and patients with malignant pericardial effusion. Patients with a CTD were three times more likely than patients without a CTD of having a recurrent pericardial effusion, independent of treatment strategy.
Funding Acknowledgement
Type of funding sources: None.
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Affiliation(s)
- C Shirkhodaie
- University of Chicago Medicine, Pritzker School of Medicine, Chicago, United States of America
| | - J M Venturini
- Edward Hospital, Naperville, United States of America
| | - A P Shah
- University of Chicago Medicine, Section of Cardiology, Chicago, United States of America
| | - S Nathan
- University of Chicago Medicine, Section of Cardiology, Chicago, United States of America
| | - J Paul
- University of Chicago Medicine, Section of Cardiology, Chicago, United States of America
| | - R Kalathiya
- University of Chicago Medicine, Section of Cardiology, Chicago, United States of America
| | - J E A Blair
- University of Chicago Medicine, Section of Cardiology, Chicago, United States of America
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10
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Shah AP, Cleland J. 1253 Unlocking Growth Options in Surgical Education and Training During the Pandemic. Br J Surg 2021. [PMCID: PMC8524564 DOI: 10.1093/bjs/znab259.901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Introduction The COVID-19 pandemic brought widespread disruption to structured surgical education and training. The knee-jerk reaction is often pessimism about surgical training’s future, particularly in the Improved Surgical Training (IST) pilot’s context. However, Einstein famously once said, “In the midst of every crises lies great opportunity”. Unlocking growth during periods of high uncertainty is a premise of real options theory; one utilised by supply chain managers and decision scientists, but novel to medical education. This study explores the growth options that have resulted from new operational models during the pandemic. Method Using a qualitative case study approach, data were obtained from interviews with core surgical trainees across Scotland. Data coding and inductive thematic analysis were undertaken. Results Forty-six trainees participated. Analysis from trainees’ perspective revealed: unexpected fulfilment from redeployment to non-surgical specialties, benefits to personal development from the unintended broad-based training across surgical specialties, improved collaborative teamworking between specialties and allied healthcare professionals, and enhanced supervised learning opportunities. Institutional growth options reported by trainees included: rapid uptake of telemedicine and digital technology, implementation of single hospital episode encounters for minor conditions, streamlined processes in theatre and acute admissions, and changes in working culture towards rationalising and teamworking. Conclusions Growth options have been deliberately and unintentionally unlocked due to individual and institutional adaptions and innovations in response to the exogenous disruption. While some changes may be temporary, hopefully structured reflection on these changes and responders to them will drive surgical education and training into a new sustainable and resilient post-pandemic era.
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Affiliation(s)
- A P Shah
- Centre for Healthcare Education Research and Innovation (CHERI), University of Aberdeen., Aberdeen, United Kingdom
| | - J Cleland
- Medical Education Research and Scholarship Unit (MERSU), LKC School of Medicine, Singapore, Singapore
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11
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Shah AP, Campbell PC, Miller SM, Woolstrum JM, Sporer BJ, Patel SG, Jordan NM, Gilgenbach RM, McBride RD. Optimization of switch diagnostics on the MAIZE linear transformer driver. Rev Sci Instrum 2019; 90:124707. [PMID: 31893831 DOI: 10.1063/1.5113866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Accepted: 11/24/2019] [Indexed: 06/10/2023]
Abstract
The MAIZE Linear Transformer Driver consists of 40 capacitor-switch-capacitor "bricks" connected in parallel. When these 40 bricks are charged to ±100-kV and then discharged synchronously, the MAIZE facility generates a 1-MA current pulse with a 100-ns rise time into a matched load impedance. Discharging each of the capacitors in a brick is carried out by the breakdown of a spark-gap switch, a process that results in the emission of light. Monitoring this output light with a fiber optic coupled to a photomultiplier tube (PMT) and an oscilloscope channel provides information on switch performance and timing jitter-whether a switch fired early, late, or in phase with the other switches. However, monitoring each switch with a dedicated detector-oscilloscope channel can be problematic for facilities where the number of switches to be monitored (e.g., 40 on MAIZE) greatly exceeds the number of detector-oscilloscope channels available. The technique of using fibers to monitor light emission from switches can be optimized by treating a PMT as a binary digit or bit and using a combinatorial encoding scheme, where each switch is monitored by a unique combination of fiber-PMT-oscilloscope channels simultaneously. By observing the unique combination of fiber-PMT-oscilloscope channels that are turned on, the prefiring or late-firing of a single switch on MAIZE can be identified by as few as six PMT-oscilloscope channels. The number of PMT-oscilloscope channels, N, required to monitor X switches can be calculated by 2N = X + 1, where the number "2" is selected because the PMT-oscilloscope acts as a bit. In this paper, we demonstrate the use of this diagnostic technique on MAIZE. We also present an analysis of how this technique could be scaled to monitor the tens of thousands of switches proposed for various next generation pulsed power facilities.
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Affiliation(s)
- A P Shah
- Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - P C Campbell
- Nuclear Engineering and Radiological Sciences Department, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - S M Miller
- Nuclear Engineering and Radiological Sciences Department, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - J M Woolstrum
- Nuclear Engineering and Radiological Sciences Department, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - B J Sporer
- Nuclear Engineering and Radiological Sciences Department, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - S G Patel
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - N M Jordan
- Nuclear Engineering and Radiological Sciences Department, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - R M Gilgenbach
- Nuclear Engineering and Radiological Sciences Department, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - R D McBride
- Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109, USA
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12
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Shah AP, Carreno FR, Wu H, Chung YA, Frazer A. Role of TrkB in the anxiolytic-like and antidepressant-like effects of vagal nerve stimulation: Comparison with desipramine. Neuroscience 2016; 322:273-86. [PMID: 26899129 DOI: 10.1016/j.neuroscience.2016.02.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Revised: 01/23/2016] [Accepted: 02/09/2016] [Indexed: 12/27/2022]
Abstract
A current hypothesis regarding the mechanism of antidepressant (AD) action suggests the involvement of brain-derived neurotrophic factor (BDNF). Consistent with this hypothesis, the receptor for BDNF (and neurotrophin 4/5 (NT-4/5)), Tropomyosin-related kinase B (TrkB), is activated in rodents by treatment with classical AD drugs. Vagal nerve stimulation (VNS), a therapy for treatment resistant depression (TRD), also activates TrkB in rodents. However, the role of this receptor in the therapeutic effects of VNS is unclear. In the current study, the involvement of TrkB in the effects of VNS was investigated in rats using its inhibitor, K252a. Anxiolytic-like and AD-like effects were analyzed using the novelty suppressed feeding test (NSFT) and forced swim test (FST), respectively. K252a blocked the anxiolytic-like effect of chronic VNS treatment and the AD-like effect of acute VNS treatment. By contrast, blocking TrkB did not prevent either the anxiolytic-like or AD-like effect of chronic treatment with desipramine (DMI), a selective noradrenergic reuptake inhibitor; it did, however, block the acute effect of DMI in the FST. To examine whether the activation of TrkB caused by either VNS or DMI is ligand-dependent, use was made of TrkB-Fc, a molecular scavenger for ligands of TrkB. Intraventricular administration of TrkB-Fc blocked the acute activation of TrkB induced by either treatment, indicating that treatment-induced activation of this receptor is ligand-dependent. The behavioral results highlight differences in the involvement of TrkB in the chronic effects of an AD drug and a stimulation therapy as well as its role in acute versus chronic effects of DMI.
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Affiliation(s)
- A P Shah
- Department of Pharmacology and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, TX, USA.
| | - F R Carreno
- Department of Pharmacology and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, TX, USA
| | - H Wu
- Department of Pharmacology and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, TX, USA
| | - Y A Chung
- Department of Pharmacology and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, TX, USA
| | - A Frazer
- Department of Pharmacology and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, TX, USA; South Texas Veterans Health Care System (STVHCS), Audie L. Murphy Division, San Antonio, TX, USA
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13
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Fenkel JM, Singh P, Shah AP, Frank AM. Need to consider full societal impact of hepatitis B virus-positive donors. Am J Transplant 2015; 15:3013. [PMID: 26372744 DOI: 10.1111/ajt.13450] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2015] [Accepted: 06/22/2015] [Indexed: 01/25/2023]
Affiliation(s)
- J M Fenkel
- Division of Gastroenterology and Hepatology, Department of Medicine, Thomas Jefferson University Hospital, Philadelphia, PA
| | - P Singh
- Division of Nephrology, Department of Medicine, Thomas Jefferson University Hospital, Philadelphia, PA
| | - A P Shah
- Division of Transplantation, Department of Surgery, Thomas Jefferson University Hospital, Philadelphia, PA
| | - A M Frank
- Division of Transplantation, Department of Surgery, Thomas Jefferson University Hospital, Philadelphia, PA
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14
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Shah AP, Mulla SA. CIRCULATING FILARIAL ANTIGEN IN SERUM AND HYDROCELE FLUID FROM INDIVIDUALS LIVING IN AN ENDEMIC AREA FOR BANCROFTIAN FILARIASIS. Indian J Med Microbiol 2007. [DOI: 10.1016/s0255-0857(21)02116-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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15
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Abstract
Respiratory involvement is a frequent complication of Stevens-Johnson syndrome (SJS). However, there are very few convincing reports of persistent pulmonary sequelae, as demonstrated by spirometry, radiology and pathology. The current study presents a case of a 13-yr-old female with T-cell acute lymphocytic leukaemia who developed persistent, severe, obstructive lung disease following an episode of SJS. A lung biopsy demonstrated bronchiolar submucosal fibrosis consistent with constrictive bronchiolitis, as well as eosinophilic micro-abscesses, which, to the current authors' knowledge, has not been previously described. The present study illustrates specific histopathological features that highlight a possible association between Stevens-Johnson syndrome, constrictive bronchiolitis and eosinophilic micro-abscesses. The eosinophils may be associated with permanent mucosal damage, as seen in the present case, by releasing mediators that have a pro-fibrogenetic role. However, further investigation is warranted.
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Affiliation(s)
- A P Shah
- Department of Medicine, Pulmonary and Critical Care Unit, University of Rochester Medical Center, Rochester, NY, USA.
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16
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Shah AP, Mulla SA. Circulating filarial antigen in serum and hydrocele fluid from individuals living in an endemic area for bancroftian filariasis. Indian J Med Microbiol 2007; 25:253-5. [PMID: 17901645 DOI: 10.4103/0255-0857.34769] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
This study examined circulating filarial antigen by monoclonal antibody Og4C3-enzyme-linked immunosorbent assay (ELISA) from 114 men with hydrocele, living in an endemic area. Nocturnal blood and hydrocele fluid were collected and examined for microfilaria. ELISA was performed on serum and hydrocele fluid for detection of antigen. Amongst 114 cases, 5(4.4%) showed microfilaria in blood but none in fluid. ELISA was positive in 13(11.40%) serum and 5 (4.4%) fluid samples. All five fluid antigen positive cases were positive for antibodies and showed microfilaria in blood. These findings emphasize the use of circulating filarial antigen detection and alternative usage of hydrocele fluid for diagnosis of filariasis.
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Affiliation(s)
- A P Shah
- Department of Microbiology, Government Medical College and New Civil Hospital, Surat - 395 001, Gujarat, India.
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17
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Bolch WE, Shah AP, Watchman CJ, Jokisch DW, Patton PW, Rajon DA, Zankl M, Petoussi-Henss N, Eckerman KF. Skeletal absorbed fractions for electrons in the adult male: considerations of a revised 50-microm definition of the bone endosteum. Radiat Prot Dosimetry 2007; 127:169-73. [PMID: 17556345 DOI: 10.1093/rpd/ncm268] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
In 1995, the International Commission on Radiological Protection (ICRP) issued ICRP Publication 70 which provided an extensive update to the physiological and anatomical reference data for the skeleton of adults and children originally issued in ICRP Publication 23. Although ICRP Publication 70 has been a valuable document in the development of reference voxel computational phantoms, additional guidance is needed for dose assessment in the skeletal tissues beyond that given in ICRP Publication 30. In this study, a computed tomography (CT) and micro-CT-based model of the skeletal tissues is presented, which considers (1) a 50-microm depth in marrow for the osteoprogenitor cells, (2) electron escape from trabecular spongiosa to the surrounding cortical bone, (3) cortical bone to trabecular spongiosa cross-fire for electrons and (4) variations in specific absorbed fraction with changes in bone marrow cellularity for electrons. A representative data set is given for electron dosimetry in the craniofacial bones of the adult male.
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Affiliation(s)
- W E Bolch
- Advanced Laboratory for Radiation Dosimetry Studies (ALRADS), Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL 32611-8300, USA.
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18
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Rajon DA, Shah AP, Watchman CJ, Brindle JM, Bolch WE. A hyperboliod representation of the bone-marrow interface within 3D NMR images of trabecular bone: applications to skeletal dosimetry. Phys Med Biol 2003; 48:1721-40. [PMID: 12870579 DOI: 10.1088/0031-9155/48/12/304] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Recent advances in physical models of skeletal dosimetry utilize high-resolution NMR microscopy images of trabecular bone. These images are coupled to radiation transport codes to assess energy deposition within active bone marrow irradiated by bone- or marrow-incorporated radionuclides. Recent studies have demonstrated that the rectangular shape of image voxels is responsible for cross-region (bone-to-marrow) absorbed fraction errors of up to 50% for very low-energy electrons (<50 keV). In this study, a new hyperboloid adaptation of the marching cube (MC) image-visualization algorithm is implemented within 3D digital images of trabecular bone to better define the bone-marrow interface, and thus reduce voxel effects in the assessment of cross-region absorbed fractions. To test the method, a mathematical sample of trabecular bone was constructed, composed of a random distribution of spherical marrow cavities, and subsequently coupled to the EGSnrc radiation code to generate reference values for the energy deposition in marrow or bone. Next, digital images of the bone model were constructed over a range of simulated image resolutions, and coupled to EGSnrc using the hyperboloid MC (HMC) algorithm. For the radionuclides 33P, 117mSn, 131I and 153Sm, values of S(marrow<--bone) estimated using voxel models of trabecular bone were shown to have relative errors of 10%, 9%, <1% and <1% at a voxel size of 150 microm. At a voxel size of 60 microm, these errors were 6%, 5%, <1% and <1%, respectively. When the HMC model was applied during particle transport, the relative errors on S(marrow<--bone) for these same radionuclides were reduced to 7%, 6%, <1% and <1% at a voxel size of 150 microm, and to 2%, 2%, <1% and <1% at a voxel size of 60 microm. The technique was also applied to a real NMR image of human trabecular bone with a similar demonstration of reductions in dosimetry errors.
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Affiliation(s)
- D A Rajon
- Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL 32611, USA
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19
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Rajon DA, Jokisch DW, Patton PW, Shah AP, Watchman CJ, Bolch WE. Voxel effects within digital images of trabecular bone and their consequences on chord-length distribution measurements. Phys Med Biol 2002; 47:1741-59. [PMID: 12069091 DOI: 10.1088/0031-9155/47/10/310] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Chord-length distributions through the trabecular regions of the skeleton have been investigated since the early 1960s. These distributions have become important features for bone marrow dosimetry; as such, current models rely on the accuracy of their measurements. Recent techniques utilize nuclear magnetic resonance (NMR) microscopy to acquire 3D images of trabecular bone that are then used to measure 3D chord-length distributions by Monte Carlo methods. Previous studies have shown that two voxel effects largely affect the acquisition of these distributions within digital images. One is particularly pertinent as it dramatically changes the shape of the distribution and reduces its mean. An attempt was made to reduce this undesirable effect and good results were obtained for a single-sphere model using minimum acceptable chord (MAC) methods (Jokisch et al 2001 Med. Phys. 28 1493-504). The goal of the present work is to extend the study of these methods to more general models in order to better quantify their consequences. First, a mathematical model of a trabecular bone sample was used to test the usefulness of the MAC methods. The results showed that these methods were not efficient for this simulated bone model. These methods were further tested on a single voxelized sphere over a large range of voxel sizes. The results showed that the MAC methods are voxel-size dependent and overestimate the mean chord length for typical resolutions used with NMR microscopy. The study further suggests that bone and marrow chord-length distributions currently utilized in skeletal dosimetry models are most likely affected by voxel effects that yield values of mean chord length lower than their true values.
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Affiliation(s)
- D A Rajon
- Department of Nuclear and Radiological Engineering, University of Florida, Gainesville 32611-8300, USA
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20
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Rajon DA, Patton PW, Shah AP, Watchman CJ, Bolch WE. Surface area overestimation within three-dimensional digital images and its consequence for skeletal dosimetry. Med Phys 2002; 29:682-93. [PMID: 12033563 DOI: 10.1118/1.1470207] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The most recent methods for trabecular bone dosimetry are based on Monte Carlo transport simulations within three-dimensional (3D) images of real human bone samples. Nuclear magnetic resonance and micro-computed tomography have been commonly used as imaging tools for studying trabecular microstructure. In order to evaluate the accuracy of these techniques for radiation dosimetry, a previous study was conducted that showed an overestimate in the absorbed fraction of energy for low-energy electrons emitted within the marrow space and irradiating the bone trabeculae. This problem was found to be related to an overestimate of the surface area of the true bone-marrow interface within the 3D digital images, and was identified as the surface-area effect. The goal of the present study is to better understand how this surface-area effect occurs in the case of single spheres representing individual marrow cavities within trabecular bone. First, a theoretical study was conducted which showed that voxelization of the spherical marrow cavity results in a 50% overestimation of the spherical surface area. Moreover, this overestimation cannot be reduced through a reduction in the voxel size (e.g., improved image resolution). Second, a series of single-sphere marrow cavity models was created with electron sources simulated within the sphere (marrow source) and outside the sphere (bone trabeculae source). The series of single-sphere models was then voxelized to represent 3D digital images of varying resolution. Transport calculations were made for both marrow and bone electron sources within these simulated images. The study showed that for low-energy electrons (<100 keV), the 50% overestimate of the bone-marrow interface surface area can lead to a 50% overestimate of the cross-absorbed fraction. It is concluded that while improved resolution will not reduce the surface area effects found within 3D image-based transport models, a tenfold improvement in current image resolution would compensate the associated errors in cross-region absorbed fractions for low-energy electron sources. Alternatively, other methods of defining the bone-marrow interface, such as with a polygonal isosurface, would provide improvements in dosimetry without the need for drastic reductions in image voxel size.
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Affiliation(s)
- D A Rajon
- Department of Nuclear and Radiological Engineering, University of Florida, Gainesville 32611-8300, USA
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21
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Patton PW, Jokisch DW, Rajon DA, Shah AP, Myers SL, Inglis BA, Bolch WE. Skeletal dosimetry via NMR microscopy: investigations of sample reproducibility and signal source. Health Phys 2002; 82:316-326. [PMID: 11845834 DOI: 10.1097/00004032-200203000-00004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Nuclear magnetic resonance microscopy has been used for several years as a means of quantifying the 3D microarchitecture of the cancellous regions of the skeleton. These studies were originally undertaken for the purpose of developing non-invasive techniques for the early detection of osteoporosis and other bone structural changes. Recently, nuclear magnetic resonance microscopy has also been used to acquire this same 3D data for the purpose of both (1) generating chord length data across bone trabeculae and marrow cavities and (2) generating 3D images for direct coupling to Monte Carlo radiation transport codes. In both cases, one is interested in the reproducibility of the dosimetric data obtained from nuclear magnetic resonance microscopy. In the first of two studies, a trabecular bone sample from the femoral head of a 51-y-old male cadaver was subjected to repeated image acquisition, image processing, image coupling, and radiation transport simulations. The resulting absorbed fractions at high electron energies (4 MeV) were shown to vary less than 4% among four different imaging sessions of the same sample. In a separate study, two femoral head samples were imaged under differing conditions of the NMR signal source. In the first case, the samples were imaged with intact marrow. These samples were then subjected to marrow digestion and immersed in Gd-doped water, which then filled the marrow cavities. Energy-dependent absorbed fraction profiles for both the marrow-intact and marrow-free samples showed essentially equivalent results. These studies thus provide encouragement that skeletal dosimetry models of improved patient specificity can be achieved via NMR microscopy in vivo.
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Affiliation(s)
- P W Patton
- Department of Nuclear and Radiological Engineering, University of Florida, Gainesville 32611-8300, USA
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22
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Patton PW, Rajon DA, Shah AP, Jokisch DW, Inglis BA, Bolch WE. Site-specific variability in trabecular bone dosimetry: considerations of energy loss to cortical bone. Med Phys 2002; 29:6-14. [PMID: 11831574 DOI: 10.1118/1.1427083] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
With continual advances in radionuclide therapies, increasing emphasis is being placed on improving the patient specificity of dose estimates to marrow tissues. While much work has been focused on determining patient-specific assessments of radionuclide uptake in the skeleton, few studies have been initiated to explore the individual variability of absorbed fraction data for electron and beta-particle sources in various skeletal sites. The most recent values of radionuclide S values used in clinical medicine continue to utilize a formalism in which electrons are transported under a trabecular bone geometry of infinite extent. No provisions are thus made for the fraction of energy lost to the cortical bone cortex of the skeletal site and its surrounding tissues. In the present study, NMR microscopy was performed on trabecular bone samples taken from the femoral head and humeral proximal epiphysis of three subjects: a 51-year male, an 82-year female, and an 86-year female. Following image segmentation and coupling to EGS4, electrons were transported within macrostructural models of the various skeletal sites that explicitly include the spatial extent of the spongiosa, as well as the thickness of the surrounding cortical bone. These energy-dependent profiles of absorbed fractions to marrow tissues were then compared to transport simulations made within an infinite region of spongiosa. Ratios of mean absorbed fraction, as weighted by the beta energy spectra, under both transport methodologies were then assembled for the radionuclides 32P and 90Y. These ratios indicate that corrections to existing radionuclide S values for 32P can vary by as much as 5% for the male, 6% for the 82-year female, and 8% for the 86-year female. For the higher-energy beta spectrum of 90Y, these same corrections can reach 8%, 10%, and 11%, respectively.
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Affiliation(s)
- P W Patton
- Department of Nuclear and Radiological Engineering, University of Florida, Gainesville 32611-8300, USA
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23
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Rajon DA, Jokisch DW, Patton PW, Shah AP, Bolch WE. Voxel size effects in three-dimensional nuclear magnetic resonance microscopy performed for trabecular bone dosimetry. Med Phys 2000; 27:2624-35. [PMID: 11128316 DOI: 10.1118/1.1315313] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
An important problem in internal dosimetry is the assessment of energy deposition by beta particles within trabecular regions of the skeleton. Recent dosimetry methods for trabecular bone are based on Monte Carlo particle transport simulations within three-dimensional (3D) images of real human bone samples. Nuclear magnetic resonance (NMR) microscopy is a 3D imaging technique of choice due to the large signal differential between bone tissue and the water-filled marrow cavities. Image voxel sizes currently used in NMR microscopy are between 50 microm and 100 microm, but the images are time consuming to acquire and can only be performed at present for in vitro samples. It is therefore important to evaluate what resolution is best suitable in order to properly characterize the trabecular microstructure, to adequately predict the tissue dosimetry, and to minimize imaging time. In this work, a mathematical model of trabecular bone, composed of a distribution of spherical marrow cavities, was constructed. The mathematical model was subsequently voxelized with different voxel sizes (16 microm to 1,000 microm) to simulate 3D NMR images. For each image, voxels are assigned to either bone or marrow according to their enclosed marrow fraction. Next, the images are coupled to the EGS4 electron transport code and absorbed fractions to bone and marrow are calculated for a marrow source of monoenergetic electrons. Radionuclide S values are also determined for the voxelized images with results compared to data calculated for the pure mathematical sample. The comparison shows that for higher energy electrons (>400 keV), good convergence of the results is seen even within images of poor resolution. Above 400 keV, a voxel resolution as large as 300 microm results in dosimetry errors below 5%. For low-energy electrons and high-resolution images, the self-dose to marrow is also determined to within 5% accuracy. Nevertheless, increased voxelization of the image overestimates the surface area of the bone-marrow interface leading to errors in the cross-dose to bone as high as 25% for some low-energy beta emitters.
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Affiliation(s)
- D A Rajon
- Department of Nuclear and Radiological Engineering, University of Florida, Gainesville 32611-8300, USA
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24
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Tewari SG, Prasad M, Ahmad KN, Gupta R, Khan RU, Shah AP. Morphology and functions of stomach in chronic obstructive lung disease. Indian J Med Res 1978; 67:145-51. [PMID: 658989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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Parikh NK, Kotadia AM, Shah AP. Ulcerative colitis in siblings. J Assoc Physicians India 1977; 25:833-5. [PMID: 614350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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27
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Shah AP, Shah SS, Doshi HV. Pemphigus vegetans. A report of a case. Indian J Med Sci 1973; 27:864-5. [PMID: 4789309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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28
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Shah AP, Shah SS, Doshi HV. Auriculo-temporal syndrome. J Assoc Physicians India 1973; 21:615-7. [PMID: 4283779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Doshi HV, Shah SS, Shah AP. Ichtryosis Vulgaris Associated with Cataract and Nephrotic Syndrome. Indian J Dermatol Venereol 1973; 39:180-183. [PMID: 29139416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
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Abstract
A case of ichthyosis vulgaris associated with tuberculoid leprosy is reported. Ichthyotic scales were markedly accentuated within the anaesthetic patches of leprosy. The probable mechanism of the accentuation of ichthyosis by leprosy is discussed.
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Shah AP, Phatak AT. A clinical trial of broxyquinoline--brobenzoxalidine in childhood diarrhoea. Indian J Pediatr 1973; 40:83-92. [PMID: 4585812 DOI: 10.1007/bf02753456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Shah KC, Mehta NR, Shah AP, Shah AC, Godbole VK. ABO Blood Groups in Leprosy. Indian J Dermatol Venereol 1972; 38:250-252. [PMID: 29144346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
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34
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Chikermane AS, Majumdar GR, Shah AP. The use of maturity score in the assessment of gestational age of newborn babies with special reference to prematurity. Indian Pediatr 1969; 6:720-8. [PMID: 5393823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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