MOSFET Measurements Research Articles

Terrestrial neutron induced failure rate measurement of SiC MOSFETs using China spallation neutron source

The atmospheric neutron induced single event burnout (SEB) is observed for SiC MOSFETs by conducting irradiation at China Spallation Neutron Source (CSNS) with maximum energy close to 1.6 GeV. The failure is manifested as a sudden loss of voltage blocking ability during irradiation and a melting region is observed for the device with SEB. The SEB failure rates of SiC MOSFETs are calculated based on the experimental results. It shows that the failure rates increase exponentially with operating voltages. The measured failure rates are consistent with the results obtained at the other spallation neutron sources, which proves that the neutron beam line at CSNS is suitable for SEB testing. The information of the secondary ions produced by neutron is obtained through Monte Carlo simulations and the contributors to SEB are analyzed. A simulation method is also applied to calculate SEB failure rate by considering ionization energy deposition of secondary ions in the sensitive region of SiC devices. The simulated failure rates are also consistent with the experimental results.

Improving total body irradiation with a dedicated couch and 3D-printed patient-specific lung blocks: A feasibility study.

Total body irradiation (TBI) is an important component of the conditioning regimen in patients undergoing hematopoietic stem cell transplants. TBI is used in very few patients and therefore it is generally delivered with standard linear accelerators (LINACs) and not with dedicated devices. Severe pulmonary toxicity is the most common adverse effect after TBI, and patient-specific lead blocks are used to reduce mean lung dose. In this context, online treatment setup is crucial to achieve precise positioning of the lung blocks. Therefore, in this study we aim to report our experience at generating 3D-printed patient-specific lung blocks and coupling a dedicated couch (with an integrated onboard image device) with a modern LINAC for TBI treatment. TBI was planned and delivered (2Gy/fraction given twice a day, over 3 days) to 15 patients. Online images, to be compared with planned digitally reconstructed radiographies, were acquired with the couch-dedicated Electronic Portal Imaging Device (EPID) panel and imported in the iView software using a homemade Graphical User Interface (GUI). In vivo dosimetry, using Metal-Oxide Field-Effect Transistors (MOSFETs), was used to assess the setup reproducibility in both supine and prone positions. 3D printing of lung blocks was feasible for all planned patients using a stereolithography 3D printer with a build volume of 14.5×14.5×17.5 cm3. The number of required pre-TBI EPID-images generally decreases after the first fraction. In patient-specific quality assurance, the difference between measured and calculated dose was generally<2%. The MOSFET measurements reproducibility along each treatment and patient was 2.7%, in average. The TBI technique was successfully implemented, demonstrating that our approach is feasible, flexible, and cost-effective. The use of 3D-printed patient-specific lung blocks have the potential to personalize TBI treatment and to refine the shape of the blocks before delivery, making them extremely versatile.

A Simple Method to Create Corners for the Lookup Table-Based MOSFET Models Through Inputs and Outputs Mapping

This article presents a simple method to create corner models to capture process variations for the lookup table-based MOSFET models through inputs and outputs mapping. The electrical specifications, including the threshold voltage, peak transconductance, ON-state resistance, saturation current, and gate oxide thickness, can be fitted through five model parameters. The effectiveness of the method is demonstrated by both the FinFET model BSIM-CMG and the planar MOSFET measurement data.

MOSFET dose measurements for proton SOBP beam.

The aim of this work was to develop a computational scheme for the correction of the LET dependence on the MOSFET response in water phantom dose measurements for a spread-out Bragg peak (SOBP) proton beam. The LET dependence of MOSFET was attributed to the stopping power ratio of SiO2 to H2O and to the fractional hole yield in the SiO2 layer. Using literature values for the stopping powers of the continuous slowing down approximation and measured fractional hole yields vs. electric field and LET, formulas were derived for the computation of a dose-weighted correction factor of a SOBP beam. Dose-weighted correction factors were computed for a clinical 190-MeV proton SOBP beam in a high-density polyethylene phantom. By applying correction factors to the SOBP beam, which consisted of weighted monoenergetic Bragg peaks, the MOSFET outputs were predicted and agreed well with the measured MOSFET responses. By applying LET dependent correction factors to MOSFET data, quality assurance of dose verification based on MOSFET measurements becomes possible for proton therapy.

Drain–Source Voltage Clamp Circuit for Online Accurate ON-State Resistance Measurement of SiC MOSFETs in DC Solid-State Power Controller

To obtain the online ON-state resistance ( ${\text{R}}_{\mathrm {dson}}$ ) of the SiC power MOSFET, during its operation in the dc solid-state-power controller (dc-SSPC), the drain current ( ${\text{I}}_{d}$ ) and the ON-state voltage ( ${\text{V}}_{\mathrm {dson}}$ ) need to be accurately measured in real time. Compared to that of ${\text{I}}_{d}$ , the measurement of ${\text{V}}_{\mathrm {dson}}$ needs to solve more problems, i.e., the high accuracy, the influence of the operating temperature ( ${\text{T}}_{w}$ ), and the high OFF-state voltage. The drain–source voltage clamp circuit (DVCC) can be accurately used to measure ${\text{R}}_{\mathrm {dson}}$ at low operating temperatures. However, the SiC power MOSFETs, owning the low ${\text{R}}_{\mathrm {dson}}$ characteristics, in the dc-SSPC often operate at the high ${\text{T}}_{w}$ . Under this high ${\text{T}}_{w}$ , the existing DVCCs cannot perform well and give inaccurate measurements of ${\text{V}}_{\mathrm {dson}}$ in real time. Therefore, this article presents an innovative design of the DVCC with improved real-time measurement accuracy ( ${\text{T}}_{w}$ range (25 °C–100 °C). The DVCC is analyzed and tested by integrating into a dc-SSPC for measuring the online ${\text{R}}_{\mathrm {dson}}$ of the SiC power MOSFET at the high ${\text{T}}_{w}$ of 100 °C. The experimental results validate the accuracy of the proposed DVCC-based measurement method and highlight the potential for its use in the accurate junction temperature measurement.

Demonstration of mm long nearly intrinsic GeSn single-crystalline wires on quartz substrate fabricated by nucleation-controlled liquid-phase crystallization

Millimeter long GeSn wires were fabricated on quartz substrates by using an advanced rapid melt growth method, named “nucleation-controlled liquid-phase crystallization” (NCLPC). Local melting of amorphous GeSn wires surrounded by SiO2 capping layers led to the propagation of single crystal growth from the solid/liquid interface without any crystal seeds and catalysts. Slow cooling just after rapid melting was beneficial in NCLPC for prolonged and stable lateral growth, and 1.7 mm long single-crystalline GeSn wires were successfully demonstrated. Physical characterizations revealed that, since excessive Sn atoms were swept out toward the growth direction, a mostly uniform GeSn single crystal, in terms of Sn content and crystallinity, was formed along the wires. Electrical measurements of top-gate MOSFETs with NCLPC-GeSn channels revealed the formation of nearly intrinsic GeSn single crystal, indicating a significant reduction in acceptor-like point defects achieved with the slow-cooling procedure.

Real-time control in single-phase power inverters

The analysis of usability of selected digital signal controllers (DSC) in off-grid power inverters is presented in this paper. The digital signal controller’s task was to control the H-bridge through dedicated driver for power MosFET transistors and measurement of higher harmonics. NexFET power transistors with small channel resistance and small FOM coefficient were used for this purpose. Regular modulation with symmetrical triangle carrier signal was used as a modulation method. The main aim was to show the capabilities of Delfino digital signal controllers in real-time control of the power inverter and analysis of the possible implementations of voltage and harmonic measurements. These measurements can be used for regulation of the output voltage and reduction of the total harmonic distortion.

The Technique for I–V Characteristic Measurements of MOSFETs from Output Stage of MOS ICs

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Junction Temperature Measurement Method for Power mosfets Using Turn-On Delay of Impulse Signal

This paper proposes a novel method for junction temperature measurement of power metal-oxide-semiconductor field-effect transistors ( mosfet s). The measurement method is using the turn- on delay of impulse signal, which is the delay time between the rising edge of impulse signal and the corresponding rising edge of drain–source current. Results show that the turn- on delay has a good linear relationship with temperature, and the method is suitably efficient for accurate junction temperature measurement of power mosfet s. The proposed method is verified using the thermal infrared method. Finally, this method is used to measure the real-time junction temperature of power mosfet device in a dc–dc boost converter.

Fetal radiation dose in three common CT examinations during pregnancy – Monte Carlo study

PurposeTo determine fetal doses in different stages of pregnancy in three common computed tomography (CT) examinations: pulmonary CT angiography, abdomino-pelvic and trauma scan with Monte Carlo (MC) simulations. MethodsAn adult female anthropomorphic phantom was scanned with a 64-slice CT using pulmonary angiography, abdomino-pelvic and trauma CT scan protocols. Three different sized gelatin boluses placed on the phantom’s abdomen simulated different stages of pregnancy. Intrauterine dose was used as a surrogate to a dose absorbed to the fetus. MC simulations were performed to estimate uterine doses. The simulation dose levels were calibrated with volumetric CT dose index (CTDIvol) measurements and MC simulations in a cylindrical CTDI body phantom and compared with ten point doses measured with metal-oxide-semiconductor field-effect-transistor dosimeters. Intrauterine volumes and uterine walls were segmented and the respective dose volume histograms were calculated. ResultsThe mean intrauterine doses in different stages of pregnancy varied from 0.04 to 1.04mGy, from 4.8 to 5.8mGy, and from 9.8 to 12.6mGy in the CT scans for pulmonary angiography, abdomino-pelvic and trauma CT scans, respectively. MC simulations showed good correlation with the MOSFET measurement at the measured locations. ConclusionsThe three studied examinations provided highly varying fetal doses increasing from sub-mGy level in pulmonary CT angiography to notably higher levels in abdomino-pelvic and trauma scans where the fetus is in the primary exposure range. Volumetric dose distribution offered by MC simulations in an appropriate anthropomorphic phantom provides a comprehensive dose assessment when applied in adjunct to point-dose measurements.

A Patient-Specific Polylactic Acid Bolus Made by a 3D Printer for Breast Cancer Radiation Therapy

PurposeThe aim of this study was to assess the feasibility and advantages of a patient-specific breast bolus made using a 3D printer technique.MethodsWe used the anthropomorphic female phantom with breast attachments, which volumes are 200, 300, 400, 500 and 650 cc. We simulated the treatment for a right breast patient using parallel opposed tangential fields. Treatment plans were used to investigate the effect of unwanted air gaps under bolus on the dose distribution of the whole breast. The commercial Super-Flex bolus and 3D-printed polylactic acid (PLA) bolus were applied to investigate the skin dose of the breast with the MOSFET measurement. Two boluses of 3 and 5 mm thicknesses were selected.ResultsThere was a good agreement between the dose distribution for a virtual bolus generated by the TPS and PLA bolus. The difference in dose distribution between the virtual bolus and Super-Flex bolus was significant within the bolus and breast due to unwanted air gaps. The average differences between calculated and measured doses in a 200 and 300 cc with PLA bolus were not significant, which were -0.7% and -0.6% for 3mm, and -1.1% and -1.1% for 5 mm, respectively. With the Super-Flex bolus, however, significant dose differences were observed (-5.1% and -3.2% for 3mm, and -6.3% and -4.2% for 5 mm).ConclusionThe 3D-printed solid bolus can reduce the uncertainty of the daily setup and help to overcome the dose discrepancy by unwanted air gaps in the breast cancer radiation therapy.

SU‐F‐T‐75: Dosimetry Considerations in the Use of Hanging‐Eye Block for Lesions of the Conjunctiva

Purpose:Superficial lesions in the conjunctiva are frequently treated with en face electrons, using a hanging block to spare dose to the lens of the eye. Dose to the tumor and lens depend on the design and setup of the block and supporting apparatus. We performed in phantom measurements in order to characterize the dose sparing effects of the block as well as the under‐dosing effect under the supporting apparatus for 6 MeV treatment.Methods:The commercial hanging block studied uses a 1.2 cm diameter tungsten cylinder supported by a 3 mm diameter acrylic rod. Point dose measurements under the hanging block, under an unblocked part of the field, and under the acrylic rod were performed using MOSFET detectors. In addition, EBT3 film was used for both PDD and profile measurements at a depth in phantom of 3 mm for both 105 and 103 cm SSD.Results:MOSFET measurements reported a dose reduction of 95% under the tungsten block when using an SSD of 103 cm, and 86% when using an SSD of 105 cm at a depth in phantom of 3 mm. Film measurements showed that the area under the acrylic rod may be under‐dosed by as much as 30% when using 103 SSD. MOSFET measurements confirmed that when using an SSD of 103 cm, the area under the acrylic rod is under‐dosed by up to 30% at 3mm depth, compared to the unblocked part of the field.Conclusion:The effectiveness of the commercial hanging block apparatus depends on setup, with 95% lens sparing possible with an SSD of 103 cm. This short SSD is necessary for sharp penumbra. At this SSD, substantial under‐dosing under the acrylic support rod is possible. This must be mitigated with either feathering, or using an alternative method of support for the tungsten block.

SU‐F‐J‐14: Kilovoltage Cone‐Beam CT Dose Estimation of Varian On‐Board Imager Using GMctdospp Monte Carlo Framework

Purpose:Although cone‐beam CT (CBCT) imaging became popular in radiation oncology, its imaging dose estimation is still challenging. The goal of this study is to assess the kilovoltage CBCT doses using GMctdospp ‐ an EGSnrc based Monte Carlo (MC) framework.Methods:Two Varian OBI x‐ray tube models were implemented in the GMctpdospp framework of EGSnrc MC System. The x‐ray spectrum of 125 kVp CBCT beam was acquired from an EGSnrc/BEAMnrc simulation and validated with IPEM report 78. Then, the spectrum was utilized as an input spectrum in GMctdospp dose calculations. Both full and half bowtie pre‐filters of the OBI system were created by using egs_prism module. The x‐ray tube MC models were verified by comparing calculated dosimetric profiles (lateral and depth) to ion chamber measurements for a static x‐ray beam irradiation to a cuboid water phantom. An abdominal CBCT imaging doses was simulated in GMctdospp framework using a 5‐year‐old anthropomorphic phantom. The organ doses and effective dose (ED) from the framework were assessed and compared to the MOSFET measurements and convolution/superposition dose calculations.Results:The lateral and depth dose profiles in the water cuboid phantom were well matched within 6% except a few areas ‐ left shoulder of the half bowtie lateral profile and surface of water phantom. The organ doses and ED from the MC framework were found to be closer to MOSFET measurements and CS calculations within 2 cGy and 5 mSv respectively.Conclusion:This study implemented and validated the Varian OBI x‐ray tube models in the GMctdospp MC framework using a cuboid water phantom and CBCT imaging doses were also evaluated in a 5‐year‐old anthropomorphic phantom. In future study, various CBCT imaging protocols will be implemented and validated and consequently patient CT images will be used to estimate the CBCT imaging doses in patients.

Measurement Issues Affecting Threshold-Voltage Instability Characterization of SiC MOSFETs

This work focuses on measurement issues that affect the accuracy of positive bias temperature instability measurements of SiC power MOSFETs using a conventional sweep technique to characterize the threshold voltage, VT. Threshold-voltage shifts occurring during stress are readily recoverable during the measurement, resulting in an underestimation in VT degradation. Recovery of VT due to gate-stress relaxation before or during the measurement was a major source of measurement error that was mitigated by performing an immediate sweep down in gate voltage, VGS, from the stress bias toward threshold. Allowing the gate bias to drop to zero just prior to measuring by sweeping VGS positively resulted in smaller observed degradation due to VT recovery. This result is important, especially in cases where the gate stress has to be completely removed before making any electrical measurements. The VT shift caused by bias stress can quickly recover and yield test results that underestimate the effect of the applied stress. A full recovery of VT was observed following a positive gate bias stress for conditions where the gate was either subject to a negative gate voltage for a few seconds, or when VGS was maintained at zero volts for several minutes.

In-vivo dosimetry for conformal arc therapy using several MOSFET in stereotactic radiosurgery computed by an inverse model

In-vivo dosimetry is still a challenge in stereotactic radiosurgery since most of treatments are delivered using rotational technique with small fields. A realistic and practical solution for these treatments delivered in conformal radiotherapy is proposed to control the absorbed dose at isocentre, using multiple surface MOSFET measurements over an arc. On the one hand, a forward method was developed to optimize the location of the detectors at the patient surface, taking into account arc length, prescribed isocentre dose, collimator and field size. On the other hand, an inverse method was used to compute the dose at isocentre for conformal arc therapy in stereotactic radiosurgery, using MOSFET measurements. Finally, the reconstructed dose at isocentre was compared to real measurement, obtained for several detectors positioned at a phantom surface. Results show that the inverse method gives good results with five MOSFET equi-spaced positioned within the arc beam course: deviation between prescribed and computed average total dose at isocentre was below 2% both for 30×30 mm2 and 18×18 mm2 field size

17 - Treatment of breast cancer with lymph nodes by volumetric arc therapy (VMAT): Pretreatment and in vivo dosimetry

Introduction: The aim of this study is to clinically implement the COMPASS 3D dosimetry and the MOSFET for pretreatment quality assurance and in vivo dosimetry of breasts cancers treatments by volumetric modulated arc therapy (VMAT). Methods: For this study, 10 patients treated with VMAT technique for breast cancer with lymph nodes were randomly selected. The treatment plans were verified using the COMPASS system with MatriXXEvolution and the collapse convolution superposition algorithm v3.1.6. This system allows on one hand independent verification of dosimetry with a 3D calculation using the patient’s scan, and on the other hand 3D verification of machines dose delivery. In both cases, histograms dose volumes and 3D gamma index were used, in order to evaluate the dose difference between the measurement/ calculation of the COMPASS and the treatment planning system calculation (Eclipse AAA v10.0.28, VARIAN®). For each patient treated with this technique, in vivo dosimetry with MOSFETs was performed during the first session. The detectors were calibrated for measurement of skin dose. Results: Regarding target volumes (lymph nodes and breast), deviations of the mean dose in the calculation of Eclipse TPS and COMPASS, respectively for the 3D independent calculation and measurement is 0.44 ± 1.83% and −0.72 ± 3.07%; and similarly for the parameters D1 (cGy) 3D independent calculation and measurement are −0.37 ± 0.68% et −0.70 ± 1.18%. Significant differences were found on D99 (cGy) parameter, 3D independent calculation: 11.32 ± 22.11%, and for the measurement: −8.69 ± 24.68%. These differences were well within the clinically tolerance level of ±5%, when analyses are done with the breast tumor volume reframed 5 mm from skin. For risk organs (heart, homolateral and contralateral lung), deviations of the mean dose in the calculation of Eclipse TPS and COMPASS for 3D independent calculation are −2.6 ± 1.92 and for measurement are −2 ± 5.6%. Average 3D gammas for target volumes and organ at risks of patients were less than 0.4. Finally, differences between the dose calculated by the TPS and measurement of MOSFETs are −0.23 ± 2.51%. These very good findings result from the fact that measurement are done at the depth of about 3 mm under the skin. Conclusion: The results of this study show that the COMPASS with MatriXXEvolution system and MOSFETs can be used for quality assurance of VMAT treatments in breast cancer.

SU‐E‐T‐124: Anthropomorphic Phantoms for Confirmation of Linear Accelerator Based Small Animal Irradiation

Purpose:To document the support of radiobiological small animal research by a modern radiation oncology facility. This study confirms that a standard, human use linear accelerator can cover the range of experiments called for by researchers performing animal irradiation. A number of representative, anthropomorphic murine phantoms were made. The phantoms confirmed the small field photon and electron beams dosimetry validated the use of the linear accelerator for rodents.Methods:Laser scanning a model, CAD design and 3D printing produced the phantoms. The phantoms were weighed and CT scanned to judge their compatibility to real animals. Phantoms were produced to specifically mimic lung, gut, brain, and othotopic lesion irradiations. Each phantom was irradiated with the same protocol as prescribed to the live animals. Delivered dose was measured with small field ion chambers, MOS/FETs or TLDs.Results:The density of the phantom material compared to density range across the real mice showed that the printed material would yield sufficiently accurate measurements when irradiated. The whole body, lung and gut irradiations were measured within 2% of prescribed doses with A1SL ion chamber. MOSFET measurements of electron irradiations for the orthotopic lesions allowed refinement of the measured small field output factor to better than 2% and validated the immunology experiment of irradiating one lesion and sparing another.Conclusion:Linacs are still useful tools in small animal bio‐radiation research. This work demonstrated a strong role for the clinical accelerator in small animal research, facilitating standard whole body dosing as well as conformal treatments down to 1cm field. The accuracy of measured dose, was always within 5%. The electron irradiations of the phantom brain and flank tumors needed adjustment; the anthropomorphic phantoms allowed refinement of the initial output factor measurements for these fields which were made in a large block of solid water.

Pulsed I-V Auto-Measurement of High Power MOSFETs without Self-Heating

A novel Sagittarius automatic Pulsed I-V measurement system was developed. This new system eliminated the self-heating effect which affected static measurements of High Power MOSFETs using conventional methods. It provided the true output conductance and trans-conductance, solved the device modeling problems caused by negative output conductance of high power devices. The automation measurement function can fulfill the mass measurement requirements of semiconductor industry with high efficiency and accuracy.

SU‐E‐J‐204: Experimental Validation of Dose Warping Accuracy From Deformable Image Registration

Purpose: The purpose of this work is to verify accuracy of deformable dose arising from deformable image registration (DIR) algorithms where the mass and density of tissue is conserved. This was done by using custom built deformable phantom mimicking bladder geometry with implanted MOSFETs that can be positioned in multiple locations thereby enabling direct measurement of dose delivered in different deformation states. Methods: The phantom was made using viscoelastic polymer which is nearly tissue equivalent with high tensile strength and elasticity. The phantom was deformed by positioning it with in a compression plate. 5 parallel air canals that run along the organ were used for positioning MOSFET detectors at multiple locations. Dose calculation was performed in undeformed geometry with varying degree of dose gradients. DIR was performed using both B‐Splines algorithm using 3D Slicer and commercial MimVista platform which uses intensity based free form algorithm. The resultant DVF was applied to the original dose distribution and compared with directly measured dose in deformed geometry at multiple locations. For IMRT fields the accuracy of dose warp was also validated by recalculating the original fluence map on the deformed data set and comparing the resultant dose distribution with the deformed dose from DIR. Results: For non IMRT type fields, both B‐Splines and MimVista yielded excellent point dose agreement to directly measured dose (within 2 cGy or 2%). For IMRT fields with large modulation since the inherent uncertainty in MOSFET measurement is 4.6%, agreement was less satisfactory. However comparison between IMRT doses recalculated in the deformed geometry with deformed dose from DIR yielded γ3%/3mm greater than 90%. Conclusion: We have verified that DIR based dose warping can yield accurate results for the algorithms studied. The magnitude of deformation and degree of dose modulation has the greatest impact on accuracy of dose warp.

Monte Carlo investigation of I‐125 interseed attenuation for standard and thinner seeds in prostate brachytherapy with phantom validation using a MOSFET

In permanent seed implant prostate brachytherapy the actual dose delivered to the patient may be less than that calculated by TG-43U1 due to interseed attenuation (ISA) and differences between prostate tissue composition and water. In this study the magnitude of the ISA effect is assessed in a phantom and in clinical prostate postimplant cases. Results are compared for seed models 6711 and 9011 with 0.8 and 0.5 mm diameters, respectively. A polymethyl methacrylate (PMMA) phantom was designed to perform ISA measurements in a simple eight-seed arrangement and at the center of an implant of 36 seeds. Monte Carlo (MC) simulation and experimental measurements using a MOSFET dosimeter were used to measure dose rate and the ISA effect. MC simulations of 15 CT-based postimplant prostate treatment plans were performed to compare the clinical impact of ISA on dose to prostate, urethra, rectum, and the volume enclosed by the 100% isodose, for 6711 and 9011 seed models. In the phantom, ISA reduced the dose rate at the MOSFET position by 8.6%-18.3% (6711) and 7.8%-16.7% (9011) depending on the measurement configuration. MOSFET measured dose rates agreed with MC simulation predictions within the MOSFET measurement uncertainty, which ranged from 5.5% to 7.2% depending on the measurement configuration (k = 1, for the mean of four measurements). For 15 clinical implants, the mean ISA effect for 6711 was to reduce prostate D90 by 4.2 Gy (3%), prostate V100 by 0.5 cc (1.4%), urethra D10 by 11.3 Gy (4.4%), rectal D2cc by 5.5 Gy (4.6%), and the 100% isodose volume by 2.3 cc. For the 9011 seed the mean ISA effect reduced prostate D90 by 2.2 Gy (1.6%), prostate V100 by 0.3 cc (0.7%), urethra D10 by 8.0 Gy (3.2%), rectal D2cc by 3.1 Gy (2.7%), and the 100% isodose volume by 1.2 cc. Differences between the MC simulation and TG-43U1 consensus data for the 6711 seed model had a similar impact, reducing mean prostate D90 by 6 Gy (4.2%) and V100 by 0.6 cc (1.8%). ISA causes the delivered dose in prostate seed implant brachytherapy to be lower than the dose calculated by TG-43U1. MC simulation of phantom seed arrangements show that dose at a point can be reduced by up to 18% and this has been validated using a MOSFET dosimeter. Clinical simulations show that ISA reduces DVH parameter values, but the reduction is less for thinner seeds.