Determination Of Correction Factors Research Articles

P179] Small field correction factors determination for the IBA razor nano chamber and the IBA razor chamber

Purpose The aim of this study was to measure small beam output factors (OFs) using the IBA Razor Nano Chamber (RNC) and the IBA Razor Chamber (RC) and to determine correction factors for comparison with Gafchromic EBT3 films. Methods The detectors were irradiated with 6 MV photon beams using a Varian TrueBeam STx system equipped with a HD multileaf collimator (MLC). Fields ranging from 0.5 × 0.5 to 10 × 10 cm2 were defined by both the X-Y collimator jaws and the MLC. The microchambers were used in parallel configuration at a source-surface distance of 100 cm and at 10 cm depth in a Sun Nuclear 3D SCANNER water phantom. Polarity correction factors kpol were evaluated for both the chambers and used to correct the raw measurements. Films were irradiated inside a Solid Water phantom in the same geometry. Results Deviations from unity of kpol were observed for field size less than 1 cm and greater than 2 cm, ranging from 0.943 to 1.025 for the RNC and from 0.970 to 1.005 for the RC. The output factors corrected for the polarity showed an underestimation for the smallest beam for both the detectors with respect to films (k = 1.033 and 1.052 for the RNC and the RC respectively). Correction factors values for beams ranging from 8 to 30 mm were close to unity. Conclusions OFs corrected for the RNC and the RC were in agreement with films, although an underestimation has been observed for the smallest beam connected to a small volume averaging effect. The similar behavior of the two ionization chambers is probably due to the same size of the electrode diameter (2 mm). Both the detectors could be used for output factors measurements in small beam geometry, albeit the magnitude of the polarity effect suggests to correct the readings carried out with the two chambers in order to achieve a better accuracy.

Determination of correction factors in beta radiation beams using Monte Carlo method

The absorbed dose rate is the main characterization quantity for beta radiation. The extrapolation chamber is considered the primary standard instrument. To determine absorbed dose rates in beta radiation beams, it is necessary to establish several correction factors. In this work, the correction factors for the backscatter due to the collecting electrode and to the guard ring, and the correction factor for Bremsstrahlung in beta secondary standard radiation beams are presented. For this purpose, the Monte Carlo method was applied. The results obtained are considered acceptable, and they agree within the uncertainties. The differences between the backscatter factors determined by the Monte Carlo method and those of the ISO standard were 0.6%, 0.9% and 2.04% for 90Sr/90Y, 85Kr and 147Pm sources respectively. The differences between the Bremsstrahlung factors determined by the Monte Carlo method and those of the ISO were 0.25%, 0.6% and 1% for 90Sr/90Y, 85Kr and 147Pm sources respectively.

Validating Fricke dosimetry for the measurement of absorbed dose to water for HDR 192Ir brachytherapy: a comparison between primary standards of the LCR, Brazil, and the NRC, Canada

Two Fricke-based absorbed dose to water standards for HDR Ir-192 dosimetry, developed independently by the LCR in Brazil and the NRC in Canada have been compared. The agreement in the determination of the dose rate from a HDR Ir-192 source at 1 cm in a water phantom was found to be within the k = 1 combined measurement uncertainties of the two standards: DNRC/DLCR = 1.011, standard uncertainty = 2.2%. The dose-based standards also agreed within the uncertainties with the manufacturer’s stated dose rate value, which is traceable to a national standard of air kerma. A number of possible influence quantities were investigated, including the specific method for producing the ferrous-sulphate Fricke solution, the geometry of the holder, and the Monte Carlo code used to determine correction factors. The comparison highlighted the lack of data on the determination of G(Fe3+) in this energy range and the possibilities for further development of the holders used to contain the Fricke solution. The comparison also confirmed the suitability of Fricke dosimetry for Ir-192 primary standard dose rate determinations at therapy dose levels.

Determination of recombination and polarity correction factors, kS and kP, for small cylindrical ionization chambers PTW 31021 and PTW 31022 in pulsed filtered and unfiltered beams

The aim of this technical communication is to provide correction factors for recombination and polarity effect for two new ionization chambers PTW PinPoint 3D (type 31022) and PTW Semiflex 3D (type 31021). The correction factors provided are for the (based on the) German DIN 6800-2 dosimetry protocol and the AAPM TG51 protocol. The measurements were made in filtered and unfiltered high-energy photon beams in a water equivalent phantom at maximum depth of the PDD and a field size on the surface of 10cm×10cm. The design of the new chamber types leads to an ion collection efficiency and a polarity effect that are well within the specifications requested by pertinent dosimetry protocols including the addendum of TG-51. It was confirmed that the recombination effect of both chambers mainly depends on dose per pulse and is independent of the filtration of the photon beam.

Synthesis of mass exchanger networks in a two-step hybrid optimization strategy

We present a new method for the synthesis of mass exchanger networks (MENs) involving packed columns. Simultaneous synthesis of MENs is typically done through the use of mixed-integer nonlinear program (MINLP) optimization, with simplifications made in the mathematical representations of the exchangers due to computational difficulty in solving large non-convex mixed-integer problems. The methodology proposed in this study makes use of the stage-wise based superstructure MINLP formulation for the network synthesis. This stage-wise superstructure model incorporates fixed mass transfer coefficients, fixed column diameters, no pressure drops, and unequal compositional mixing for models. In this paper, the simplified MINLP model is further improved by including a detailed individual packed column design in a non-linear programming (NLP) sub-optimization step, where orthogonal collocation is utilized for the partial differential equations, and optimal packing size, column diameter, column height, pressure drops, and fluid velocities. Detailed designs are then used to determine correction factors that update the simplified stage-wise superstructure models to more accurately portray the chosen design. Once the MINLP is updated with these correction factors, the model is re-run, with new correction factors obtained. This iterative procedure is repeated until convergence between the objective function of the MINLP and that of the NLP sub-optimization is achieved, or until a maximum number of iterations is reached. The methodology is applied to two examples and is shown to be robust and effective in generating new topologies, and in finding superior networks that are physically realizable.

Determination of velocity correction factors for real-time air velocity monitoring in underground mines

When there are installations of air velocity sensors in the mining industry for real-time airflow monitoring, a problem exists with how the monitored air velocity at a fixed location corresponds to the average air velocity, which is used to determine the volume flow rate of air in an entry with the cross-sectional area. Correction factors have been practically employed to convert a measured centerline air velocity to the average air velocity. However, studies on the recommended correction factors of the sensor-measured air velocity to the average air velocity at cross sections are still lacking. A comprehensive airflow measurement was made at the Safety Research Coal Mine, Bruceton, PA, using three measuring methods including single-point reading, moving traverse, and fixed-point traverse. The air velocity distribution at each measuring station was analyzed using an air velocity contour map generated with Surfer®. The correction factors at each measuring station for both the centerline and the sensor location were calculated and are discussed.

Windowless extrapolation chamber measurement of surface dose rate from a 90Sr/90Y ophthalmic applicator

In this study, a planar extrapolation chamber without an entrance window was tested through measurements of a 90Sr/90Y ophthalmic applicator that had been previously calibrated at the National Institute of Standards and Technology (NIST). This work was performed as part of a larger aim to determine surface dose rate from curved 106Ru/106Rh plaques using a convex windowless extrapolation chamber. Capacitance measurements were carried out to assess the initial air gap width between the source face and collecting electrode. The EGSnrc DOSRZnrc Monte Carlo user code was used to determine correction factors for backscatter, divergence, and attenuation caused by the aluminized Mylar® entrance window in the NIST extrapolation chamber. Measured surface dose rate values were compared with the expected result from the NIST source calibration, and the average observed difference was +4.1% with a standard deviation of ±0.6%. The dose rate from each measurement trial was within the estimated combined uncertainty in the reference source calibration of ±7.0% (k = 2) given by NIST. The experiment results suggest that an entrance window is not needed to achieve accurate dose rate measurements for a beta-emitting source with a planar extrapolation chamber, as long as the collecting electrode diameter is small compared to the source diameter. Therefore, a convex extrapolation chamber without an entrance window is proposed for the calibration of concave 106Ru/106Rh episcleral plaques.

Improving accuracy of asphalt content determination by ignition test

Accurate determination of asphalt content and aggregate gradation is critical for controlling quality of asphalt mixtures during construction. Most state specifications require quantitative evaluation of the asphalt content of mixes as a criterion for acceptance. The ignition oven test procedure specified in AASHTO T 308 (Standard method of test for determining the asphalt binder content of Hot Mix Asphalt [HMA] by the ignition method) is required or allowed by most state DOTs for determining the asphalt content and aggregate gradation of asphalt mixtures. The ignition oven test specified in AASHTO T 308 procedure requires the determination of asphalt content correction factors for each asphalt mix and for each ignition oven used. However, in some instances when numerous asphalt mix designs and several ignition ovens are available, correction factors (CFs) are shared between ignition units, even when that practice is not allowed by the standard. There is a need to identify the consequences of sharing correction factors between units/mixes and also to identify testing parameters that affect the measured CFs. By identifying possible causes of variation, the test procedure could be adjusted to make the CFs more consistent between ignition ovens. Also, it should be possible to reduce the amount of difference in CFs between all types of equipment. A study was conducted to assess the variability of ignition oven CFs for different ignition oven unit brands and mixes to better understand the implications of sharing CFs. Twenty-three laboratories used various brands of ovens to test four mixes containing aggregates with varying CFs. The results indicated that CFs were significantly different for the different mixes even when the same unit brand was used. The within-lab and between-lab precision developed in this study suggests that different precision statements are necessary for aggregates with high breakdown potential and that the current precision included in AASHTO T 308 was likely developed for low weight loss aggregate making it unacceptable to use for aggregates with higher CFs. It was also found that the addition of lime caused no significant difference in the measured asphalt content when the CF was correctly measured. However, it was cautioned that a change in amount of lime during mixture production would affect the measured asphalt content. In addition, ways to minimise variability in asphalt CF were evaluated. It was determined that ignition tests conducted at lower temperature (427°C) proved to be effective in reducing the variability in measured asphalt content since the lower temperature reduced the asphalt correction factors for asphalt mixes.

Abstract ID: 28 Evaluation of silicon and diamond based microdosimetry for boron neutron capture therapy quality assurance

The shift from reactor to accelerator based neutron production has created a renewed interested in Boron Neutron Capture Therapy (BNCT). BNCT is reliant upon the favourable uptake of boron 10 by tumour cells along with the interaction with neutrons to produce high LET fragments (He and Li nuclei) that deposit energy locally within the tumour site. As with any radiation based treatment, Quality Assurance (QA) is crucial. This study extends previous work regarding the application of solid state microdosimetry in the field of BNCT by means of a dedicated Monte Carlo simulation [1] . Geant4 was used to model and optimise the design of silicon on insulator and diamond based microdosimeters [2] , [3] . Detector optimisation in this context pertains to the geometry and materials (i.e., sensitive volume size and probability of neutron activation) to be used in the fabrication of detectors. The study has shown conclusively that whilst the materials currently used in the fabrication of silicon and diamond based microdosimeters are appropriate, there are changes with respect to the sensitive volume thickness that must be addressed. Lastly, the applicability of previously determined correction factors [4] to match the energy deposition response of charged particles within silicon/diamond to water was evaluated within the context of BNCT. Full results and analysis will be presented.

Experimental analysis of correction factors for reference dosimetry in a magnetic field

Abstract Today, hybrid systems of linear accelerator and MRI scanner are clinically available. Therefore it is important to investigate the feasibility of reference dosimetry with ionization chambers in the presence of a magnetic field and determine correction factors. In this work, correction factors under various conditions that influence the chamber response were experimentally investigated, using a conventional 6 MV linear accelerator together with a stand-alone magnet. We found that the correction factor for a PTW31010 ionization chamber ranges from 0.9873 to 1.009 depending on the magnetic field strength, magnetic field orientation and magnetic field size. The phantom material also does have an influence on the measured signal. Therefore, reference dosimetry with ionization chambers in the presence of a magnetic field is feasible, but requires dedicated correction factors, which depend on the experimental setup.

Monte Carlo and experimental determination of correction factors for gamma knife perfexion small field dosimetry measurements

Detector-, field size- and machine-specific correction factors are required for precise dosimetry measurements in small and non-standard photon fields. In this work, Monte Carlo (MC) simulation techniques were used to calculate the and correction factors for a series of ionization chambers, a synthetic microDiamond and diode dosimeters, used for reference and/or output factor (OF) measurements in the Gamma Knife Perfexion photon fields. Calculations were performed for the solid water (SW) and ABS plastic phantoms, as well as for a water phantom of the same geometry. MC calculations for the correction factors in SW were compared against corresponding experimental results for a subset of ionization chambers and diode detectors. Reference experimental OF data were obtained through the weighted average of corresponding measurements using TLDs, EBT-2 films and alanine pellets. values close to unity (within 1%) were calculated for most of ionization chambers in water. Greater corrections of up to 6.0% were observed for chambers with relatively large air-cavity dimensions and steel central electrode. A phantom correction of 1.006 and 1.024 (breaking down to 1.014 from the ABS sphere and 1.010 from the accompanying ABS phantom adapter) were calculated for the SW and ABS phantoms, respectively, adding up to corrections in water. Both measurements and MC calculations for the diode and microDiamond detectors resulted in lower than unit correction factors, due to their denser sensitive volume and encapsulation materials. In comparison, higher than unit results for the ionization chambers suggested field size depended dose underestimations (being significant for the 4 mm field), with magnitude depending on the combination of contradicting phenomena associated with volume averaging and electron fluence perturbations. Finally, the presence of 0.5 mm air-gap between the diodes’ frontal surface and their phantom-inserts may considerably influence OF measurements, reaching 4.6% for the Razor diode.

Radiation dosimetry in magnetic fields with Farmer-type ionization chambers: determination of magnetic field correction factors for different magnetic field strengths and field orientations

The aim of this work was to determine magnetic field correction factors that are needed for dosimetry in hybrid devices for MR-guided radiotherapy for Farmer-type ionization chambers for different magnetic field strengths and field orientations. The response of six custom-built Farmer-type chambers irradiated at a 6 MV linac was measured in a water tank positioned in a magnet with magnetic field strengths between 0.0 T and 1.1 T. Chamber axis, beam and magnetic field were perpendicular to each other and both magnetic field directions were investigated. EGSnrc Monte Carlo simulations were compared to the measurements and simulations with different field orientations were performed. For all geometries, magnetic field correction factors, , and perturbation factors were calculated. A maximum increase of 8.8% in chamber response was measured for the magnetic field perpendicular to chamber and beam axis. The measured chamber response could be reproduced by adjusting the dead volume layer near the chamber stem in the Monte Carlo simulations. For the magnetic field parallel to the chamber axis or parallel to the beam, the simulated response increased by 1.1% at maximum for field strengths up to 1.1 T.A complex dependence of the response was found on chamber radius, magnetic field strength and orientation of beam, chamber axis and magnetic field direction. Especially for magnetic fields perpendicular to beam and chamber axis, the exact sensitive volume has to be considered in the simulations. To minimize magnetic field correction factors and the influence of dead volumes on the response of Farmer chambers, a measurement set-up with the magnetic field parallel to the chamber axis or parallel to the beam is recommended for dosimetry.

Methodology for determination of correction factors in direct gamma spectrometric measurement of radionuclides in sediments

In this study, the practical methodologies are described for the determination of the factors for the self-absorption effect (Fs), spectral interferences (Fcsi), and true coincidence summing effects (Fcoi), which are used in direct gamma-spectrometric measurement of radionuclides such as 210Pb, 238U, 234Th, 226Ra, 214Pb, 228Ac, 208Tl, 214Bi, 137Cs and 40K in samples. To validate the applied methods, certified reference materials (CRMs) of lake and stream sediments were measured with an n-type Germanium (Ge) detector-calibrated using a multinuclide reference source. The highest self-absorption correction factors ranged from Fs = 1.44–2.10 for 46.5keV peak (210Pb) and Fs = 1.25–1.60 for 63.3keV peak (234Th) lying in the low energy region of the spectrum. The systematic influence was observed for 186.2keV (226Ra) peak due to spectral interferences with the 235U contribution. For this peak, Fcsi is changed from 0.921 to 0.955. Additionally, the present study suggests that true coincidence summing (TCS) effects are not dominant, except for 208Tl and 214Bi for which Fcoi ranged from 1.179 to 1.192 an ranged from 1.140 to 1.151, respectively.

Measurement of lipid composition in human skeletal muscle and adipose tissue with 1 H-MRS homonuclear spectral editing.

Accumulation of triglycerides in nonadipose tissue (e.g. ectopic lipids) is characteristic of metabolic derangements and is linked to insulin resistance and cardiovascular disease. Although the detrimental effects of the total amount of ectopic fat has been established, the role of composition of the ectopic lipid stores is unknown. In this study we used proton magnetic resonance spectroscopy (1 H-MRS) homonuclear spectral editing to characterize lipid stores in adipose tissue and skeletal muscle at 4 T. A MEGA-sLASER sequence was used to selectively detect lipid resonances that are scalar coupled to the methine resonance at 5.31 ppm and that can be used to estimate saturated fatty acid and mono- and polyunsaturated fatty acids. Phantom experiments were performed to empirically determine correction factors for editing efficiency of the different lipid groups. The spectral editing approach enabled the estimation of saturated, mono-unsaturated, and polyunsaturated fatty acid contributions in phantoms and in vivo. These estimations are in the same order as reported in studies using invasive biopsies. In this study, we have shown the feasibility of spectral editing techniques for ectopic lipid store characterization with 1 H-MRS, regardless of spectral resolution (e.g., B0- field strength). This new approach offers the opportunity to study ectopic lipid composition in relation to metabolic diseases. Magn Reson Med 79:619-627, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Field correction factors for a PTW-31016 Pinpoint ionization chamber for both flattened and unflattened beams. Study of the main sources of uncertainties.

The primary aim of this study was to determine correction factors, kQclin,Qmsrfclin,fmsr for a PTW-31016 ionization chamber on field sizes from 0.5 cm × 0.5 cm to 2 cm × 2 cm for both flattened (FF) and flattened filter-free (FFF) beams produced in a TrueBeam clinical accelerator. The secondary objective was the determination of field output factors, ΩQclin,Qmsrfclin,fmsr over this range of field sizes using both Monte Carlo (MC) simulation and measurements. kQclin,Qmsrfclin,fmsr for the PTW-31016 chamber were calculated by MC simulation for field sizes of 0.5 cm × 0.5 cm, 1 cm × 1 cm, and 2 cm × 2 cm. MC simulations were performed with the PENELOPE code system for the 10 MV FFF Particle Space File from a TrueBeam linear accelerator (LINAC) provided by the manufacturer (Varian Medical Systems, Inc. Palo Alto, CA, USA). Simulations were repeated taking into account chamber manufacturing tolerances and accelerator jaw positioning in order to assess the uncertainty of the calculated correction factors. Output ratios were measured on square fields ranging from 0.5 cm × 0.5 cm to 10 cm × 10 cm for 6 MV and 10 MV FF and FFF beams produced by a TrueBeam using a PTW-31016 ionization chamber; a Sun Nuclear Edge detector (SunNuclear Corp., Melbourne, FL, USA) and TLD-700R (Harshaw, Thermo Scientific, Waltham, MA, USA). The validity of the proposed correction factors was verified using the calculated correction factors for the determination of ΩQclin,Qmsrfclin,fmsr using a PTW-31016 at the four TrueBeam energies and comparing the results with both TLD-700R measurements and MC simulations. Finally, the proposed correction factors were used to assess the correction factors of the SunNuclear Edge detector. The present work provides a set of MC calculated correction factors for a PTW-31016 chamber used on a TrueBeam FF and FFF mode. For the 0.5 cm × 0.5 cm square field size, kQclin,Qmsrfclin,fmsr is equal to 1.17 with a combined uncertainty of 2% (k = 1). A detailed analysis of the most influential parameters is presented in this work. PTW-31016 corrected measurements were used for the determination of ΩQclin,Qmsrfclin,fmsr for 6 MV and 10 MV FF and FFF and the results were in agreement with values obtained using a TLD-700R detector (differences < 3% for a 0.5 cm square field) for the four energies studied. Uncertainty in field collimation was found to be the main source of influence of ΩQclin,Qmsrfclin,fmsr and caused differences of up to 15% between calculations and measurements for the 0.5 cm × 0.5 cm field. This was also confirmed by repeating the same measurements at two different institutions. This study confirms the need to introduce correction factors when using a PTW-31016 chamber and the hypothesis of their low energy dependence. MC simulation has been shown to be a useful methodology to determine detector correction factors for small fields and to analyze the main sources of uncertainty. However, due to the influence of the LINAC jaw setup for field sizes below or equal to 1 cm, MC methods are not recommended in this range for field output factor calculations.

Determination of self-attenuation correction factor for lichen samples by using gamma-ray spectrometry

Abstract In this study, we determine the self attenuation correction factor for lichen samples collected from Erzurum, a city located in the eastern region of Turkey by using gamma-ray spectrometry. The self attenuation correction factor is calculated for 17 lichen samples with densities ranging from 0.683 g/cm3 to 0.886 g/cm3. The transmission method has been used to obtain self-attenuation correction factors. Self attenuation correction factor versus energy fit curve is presented. It is observed that self attenuation correction factor changes with density. At lower energies the self-attenuation correction factor has higher values. At higher energies it has smaller values and tends to become stable.

Direct determination of kQ for Farmer-type ionization chambers in a clinical scanned carbon ion beam using water calorimetry

Until now, the dosimetry of carbon ions with ionization chambers has not reached the same level of accuracy as that of high-energy photons. This is mainly caused by the approximately threefold larger uncertainty of the kQ factor of ionization chambers, which, due to the lack of experimental data, is still derived by calculations. Measurements of absorbed dose to water, Dw, by means of water calorimetry have now been performed in the entrance channel of a scanned 6 cm × 6 cm radiation field of 429 MeV/u carbon ions, allowing the direct calibration of ionization chambers and thus the experimental determination of kQ. Within this work, values for kQ have been determined for the Farmer-type ionization chambers FC65-G and TM30013. A detailed investigation of the radiation field enabled the accurate determination of correction factors needed for both calorimetric and ionometric measurements. Finally, a relative standard measurement uncertainty of 0.8% (k = 1) could be achieved for the experimental kQ values.For both chambers, the experimental kQ factors were found to be about 1% larger than those tabulated in the German DIN 6801-1 protocol, whereas compared to the theoretical values stated in the TRS-398 protocol, the experimental kQ value agrees within 0.4% for the TM30013 chamber but is about 1% lower in the case of the FC65-G chamber.

Determination of evidence correction factors based on the neural network

AbstractA modified method to combine evidence based on artificial neural network and Dempster's rule of combination is proposed. The comprehensive discounting factor of this method adds learning and data mining capability to evidence combination, making it more suitable for the interrelated, conflicted evidence, or evidence with different importance and more suitable for group decision making. This method can be used for repeatable and verifiable systems. A study about securities market experts group prediction is conducted to verify the effectiveness of the proposed method.

New method for determining correction factors for pin-in-paste solder volumes

PurposeThis paper aims to present a new method to calculate the appropriate volume of solder paste necessary for the pin-in-paste (PIP) technology. By the aid of this volume calculation, correction factors have been determined, which can be used to correct the solder fillet volume obtained by an explicit expression.Design/methodology/approachThe method is based on calculating the optimal solder fillet shape and profile for through-hole (TH) components with given geometrical sizes. To calculate this optimal shape of the fillet, a script was written in Surface Evolver. The volume calculations were performed for different fillet radiuses (0.4-1.2 mm) and for different component lead geometries (circular and square cross-sections). Finally, the volume obtained by the Evolver calculations was divided by the volume obtained by an explicit expression, and correction factors were determined for the varying parameters.FindingsThe results showed that the explicit expression underestimates the fillet volume necessary for the PIP technology significantly (15-35 per cent). The correction factors for components with circular leads ranged between 1.4 and 1.59, whereas the correction factors for square leads ranged between 1.1 and 1.27. Applying this correction can aid in depositing the appropriate solder paste volume for TH components.Originality/valueDetermining the correct volume of solder paste necessary for the PIP technology is crucial to eliminate the common soldering failure of TH components (e.g. voiding or non-wetted solder pads). The explicit expression, which is widely used for volume calculation in this field, underestimates the necessary volume significantly. The new method can correct this estimation, and can aid the industry to approach zero-defect manufacturing in the PIP technology.

Dynamic Estimation of FRET Correction Factors to Study Redox Protein Interactions

Fluorescence resonance energy transfer (FRET) method is a key tool to determine molecular proximity and conformation changes of biomolecules in living cells. As the distance change between donor and acceptor fluorescent proteins attached to target proteins occurs in the range of 1-10 nm, an appreciable energy transfer can be detected at spatial and temporal resolution. Therefore it provides the most sensitive approach to study intercellular protein dynamics. Despite the earlier methods for characterization of FRET efficiency that accounts for donor and acceptor expression levels in cells; spectral bleed-through due to broad emission of fluorescent proteins results in inadequate computation of FRET, therefore efficiency and distance change cannot be determined accurately. Normalized FRET (nFRET) by using correction factors, were used to extract after FRET pair establishes an equilibrium state. However, photobleaching, varying expression of FRET pair, uncorrelated dipole orientations of fluorescent proteins, heterogeneous distance changes of linkers between donor and acceptor result in incomplete computation of nFRET since correction factors were not dynamically determined during data acquisition. Thus, the use of single bleed through coefficient for computation of netFRET values may also results in overestimation of efficiency and distance. We demonstrated that donor and acceptor bleed-through values changes during the data acquisition. Therefore, netFRET cannot be computed by a single donor-acceptor correction factors. Alternatively, we presented here dynamic coefficient estimation method to determine correction factors by using the ratio of emissions from FRET channel and donor/acceptor channels for each frame after fitting pixel intensity values and later used them to compute nFRET efficiencies. The method yields a 0.38 nFRET values for Cerulean-Venus (Cer17Ven) FRET pair separated by a short linker, however the use of static coefficients of average or minimum factors yields 0.34 nFRET value. Single coefficient incorrectly reports distance change when the measurements were taken before an equilibrium state. Furthermore, method was used to measure heme induced intercellular conformation changes of Cytochrome c labeled with Cer and Ven fluorescent pairs. The distance after Cyt c folded by Heme Lyase was accurately computed. As a result, a new approach was demonstrated to determine the nFRET efficiency and its direct use to compute distance changes. Taking all values during the data acquisition eliminated the coefficient dependent variation.