Irregular Electron Research Articles

Hemagglutination in gill capillaries of sheepshead, Archosargus probatocephalus (Perciformes: Sparidae), infected by a myxosporidean.

During a survey Myxozoa, four specimens of the sheepshead (18 ± 1.5 cm and 59 ± 2.5 g) (Archosargus probatocephalus) were collected in the Ipioquinha river (Maceió/AL). Transmission electron microscopy observations revealed erythrocyte agglutinations in gill capillaries located near spherical cysts containing myxospores of the genus Henneguya. This hemagglutination partially or totally obstructed the gill capillaries. Erythrocytes occurred in close adherence to each other, with a closed intercellular space. A few lysed erythrocytes were observed among agglutinated cells. The reduced lumen of the capillaries was partially filled with amorphous dense homogenous material adhering to the erythrocytes. In addition, heterogeneous masses of irregular lower electron density were observed in the reduced channel of the capillary. The agglutinated erythrocytes appeared dense and homogenous, lacking cytoplasmic organelles. The nuclei had the appearance of normal condensed chromatin masses, generally without visible nucleoli. This occurrence of hemagglutination only in the capillaries located in close proximity to the developing myxozoan cysts suggests that parasite development may be a factor triggering erythrocyte agglutination. This is supported by previous experimental studies that showed a probable correlation between parasitic infections and hemagglutination. Nonetheless, further studies are necessary in order to better understand the physicochemical processes involved in this phenomenon.

Characterization of irregular electron beam for boost dose after whole breast irradiation.

this work aims to measure the electron beam fluence within different field dimensions and the deviation from measurement performed in standard square electron applicator beam flatness and symmetry, then to calculate the average range of the correction factor required to overcome the loss of lateral electron equilibrium. the electron beam used in this work generated from the linear accelerator model ELEKTA Precise and dosimetry system used were a pair of PTW Pin Point ion chambers for electron beam dosimetry at standard conditions and assessment of beam quality at a reference depth of measurement, with an automatic water phantom, then a Roos ion chamber was used for absolute dose measurement, and PTW 2Darray to investigate the beam fluence of four applicators 6, 10, 14 and 20 cm2 and 4 rectangular cutouts 6×14, 8×14, 6×17 and 8×17 cm2, the second part was clinical application which was performed in a precise treatment planning system and examined boost dose after whole breast irradiation. revealed that lower energy (6MeV and 8MeV) showed the loss of lateral electron equilibrium and deviation from measurements of a standard applicator more than the high energy (15 MeV) which indicated that the treatment of superficial dose with 6MeV required higher monitor unit to allow for the loss of lateral electron equilibrium and higher margin as well.

Performance improvements of AlGaN-based deep-ultraviolet light-emitting diodes with specifically designed irregular sawtooth hole and electron blocking layers

A new structures for efficient AlGaN based deep-ultraviolet light-emitting diode (DUV -LED) with irregular sawtooth hole barrier layer (HBL) and electronic barrier layer (EBL) is proposed in this work. Optical output power and internal quantum efficiency(IQE), the energy band diagrams, radiative recombination rate are investigated by APSYS software. The results indicate that light output power of the DUV-LED with the new structure is enhanced by 131.8%, and internal quantum efficiency is increased by 125.0% at an injection current of 180 mA compared with the conventional AlGaN based DUV-LED structure. Further research shows that irregular sawtooth hole blocking layer(HBL) and electron blocking layer(EBL) can obviously improve the carrier radiation recombination rate, modulate carrier distribution, enhance electron injection efficiency, and confine hole leakage; thus the IQE and optical output power are enhanced.

Improved performance of near UV light-emitting diodes with a composition-graded p-AlGaN irregular sawtooth electron-blocking layer**Project supported by the National Natural Science Foundation of China (Grant Nos. 11474105 and 51172079), the Science and Technology Program of Guangdong Province, China (Grant Nos. 2015B090903078 and 2015B010105011), the Program for Changjiang Scholars and Innovative Research Team in University, China (Grant No. IRT13064), the Science

We investigate the performances of the near-ultraviolet (about 350 nm–360 nm) light-emitting diodes (LEDs) each with specifically designed irregular sawtooth electron blocking layer (EBL) by using the APSYS simulation program. The internal quantum efficiencies (IQEs), light output powers, carrier concentrations in the quantum wells, energy-band diagrams, and electrostatic fields are analyzed carefully. The results indicate that the LEDs with composition-graded p-AlxGa1−xN irregular sawtooth EBLs have better performances than their counterparts with stationary component p-AlGaN EBLs. The improvements can be attributed to the improved polarization field in EBL and active region as well as the alleviation of band bending in the EBL/p-AlGaN interface, which results in less electron leakage and better hole injection efficiency, thus reducing efficiency droop and enhancing the radiative recombination rate.

Qualitative analysis of irregular fields delivered with dual electron multileaf collimator: A Monte Carlo study

Abstract The use of a dual electron multileaf collimator (eMLC) to collimate therapeutic electron beam without the use of cutouts has been previously shown to be feasible. Further Monte Carlo simulations were performed in this study to verify the nature and appearance of the isodose distribution in water phantom of irregular electron beams delivered by the eMLC. Electron fields used in this study were selected to reflect those used in electron beam therapy. Results of this study show that the isodose distribution in a water phantom obtained from the simulation of irregular electron beams through the eMLC conforms to the pattern of the eMLC used in the delivery of the beam. It is therefore concluded that the dual eMLC could deliver isodose distributions reflecting the pattern of the eMLC field that was used in the delivery of the beam.

Spline modelling electron insert factors using routine measurements

There are many methods available to predict electron output factors; however, many centres still measure the factors for each irregular electron field. Creating an electron output factor prediction model that approaches measurement accuracy – but uses already available data and is simple to implement – would be advantageous in the clinical setting. This work presents an empirical spline model for output factor prediction that requires only the measured factors for arbitrary insert shapes. Equivalent ellipses of the insert shapes are determined and then parameterised by width and ratio of perimeter to area. This takes into account changes in lateral scatter, bremsstrahlung produced in the insert material, and scatter from the edge of the insert. Agreement between prediction and measurement for the 12 MeV validation data had an uncertainty of 0.4% (1SD). The maximum recorded deviation between measurement and prediction over the range of energies was 1.0%. The validation methodology showed that one may expect an approximate uncertainty of 0.5% (1SD) when as little as eight data points are used. The level of accuracy combined with the ease with which this model can be generated demonstrates its suitability for clinical use. Implementation of this method is freely available for download at https://github.com/SimonBiggs/electronfactors.

SU-E-T-601: Output Factor Calculation of Irregular Shape Electron Cutout at Extended SSD

Purpose: To calculate the output factor of irregular shape electron beam at extended SSD using modified lateral build-up-ratio method. Methods: Circular cutouts from 2.0cm diameter to maximum possible sizes were prepared for applicator cone size of 15×15cm. In addition, different irregular cutouts were prepared. Percentage depth dose (PDD) curves were measured for each cutout using 6, 9, 12 and 16-MeV at the standard SSD of 100cm. The scanning was done using Multidata system and Scanditronix diodes on 2100SC Varian LINAC. In addition, for each cutout and electron beam energy doses were measured at SSD values of 100, 105, 110, 115cm using EDR2 films and diodes. Results: The measured PDD were normalized to the depth of 1.0mm. The lateral build-up-ratio (LBR) and the lateral scatter parameter (sigma) were calculated for each circular cutout using the open 15×15-cm2 field as the reference field. Taking the linear increase of sigma with cutout size into account, PDD of the irregular cutouts were calculated at 100 cm SSD. Furthermore, using the dose measured at different SSDs, the effective SSD value for each circular cutout and electron beam energy was determined. Employing the LBR and the effective-SSD values of the circular cutouts along with the calculated PDD of the irregular cutouts, the output factors of the irregular cutout at different extended SSD values were calculated. Finally, the calculated output factors were compared with the measured values. Conclusion: In this research, it is shown that output factor of irregular shape electron beam at extended SSD can be determined by using the LBR and the effective SSD values of circular cutouts. The percentage difference of the calculated output factor from the measured output factor for irregular cutouts at extended SSD were within 3.0%.

Global S4 index variations observed using FORMOSAT‐3/COSMIC GPS RO technique during a solar minimum year

In this paper, presented for the first time the three‐dimensional global morphology and seasonal variations of scintillation index (S4 index) measured from the signal‐to‐noise ratio (SNR) intensity fluctuations of L1 channel of GPS radio occultation (RO) signals using FORMOSAT‐3/COSMIC (in short, F3/C) satellites for a low solar activity year 2008. The S4 index, which confined around ±30° magnetic latitudes, is found to start around post‐sunset hours (1900 MLT, magnetic local time) and often persists till post‐midnight hours (0300 MLT) between 150 and 350 km altitudes during equinox and northern winter seasons while no activity is observed during southern winter season. However, high latitudes are characterized with no scintillation activity beyond 150 km during any season, which implying that in the solar minimum period the drives of instabilities in the auroral, cusp and polar cap regions, namely the gradient drift and velocity shear, are absent. The S4 index at F region altitudes during magnetically quiet times is more intense and extends to higher latitudes than that observed during disturbed time consistent with earlier studies. The equatorial S4 index appears below the peak of F2 layer (hmF2) during most of the seasons although the associated intensities and the time of maximum occurrences are relatively higher and earlier during vernal equinox followed by autumn equinox. This equinoctial asymmetry could be primarily attributed to the asymmetries in eastward drift velocities, thermospheric meridional winds and plasma densities. Further, the global maps of S4 index at E region altitudes (between 75 and 125 km) show strong seasonal variations with highest activity during northern and southern summer solstice in the middle latitudes while it appears on both sides of magnetic equator with less or no activity at and around the equator during equinox seasons. The absence of S4 index along the equator can be understood in terms of the vanishing vertical component of the magnetic field lines that can inhibit the vertical movement and layered deposition of ionized particles of thin irregular electron density layers such as Es‐layers. Keeping in view the importance of these valuable database, we would like to emphasize that the F3/C GPS RO technique can be used to study the ionospheric irregularities at GHz frequency globally directly from the high‐rate L1 data, which reiterating its importance as a powerful tool to explore the terrestrial ionosphere on a global scale.

SU-F-BRCD-03: Dose Calculation of Electron Therapy Using Improved Lateral Buildup Ratio Method.

To calculate the percentage depth dose of any irregular shape electron beam using modified lateral build-up-ratio method. Percentage depth dose (PDD) curves were measured using 6, 9, 12, and 15MeV electron beam energies for applicator cone sizes of 6×6, 10×10, 14×14, and 14×14cm2 . Circular cutouts for each cone were prepared from 2.0cm diameter to the maximum possible size for each cone. In addition, three irregular cutouts were prepared. The scanning was done using a water tank and two diodes - one for the signal and the other a stationary reference outside the tank. The water surface was determined by scanning the signal diode slowly from water to air and by noting the sharp change of the percentage depth dose curve at the water/air interface. The lateral build-up-ratio (LBR) for each circular cutout was calculated from the measured PDD curve using the open field of the 14×14 cm2 cone as the reference field. Using the LBR values and the radius of the circular cutouts, the corresponding lateral spread parameter (sigma) of the electron shower was calculated. Unlike the commonly accepted assumption that sigma is independent of cutout size, it is shown that the sigma value increases linearly with circular cutout size. Using this characteristic of sigma, the PDD curves of irregularly shaped cutouts were calculated. Finally, the calculated PDD curves were compared with measured PDD curves. In this research, it is shown that sigma increases with cutout size. For radius of circular cutout sizes up to the equilibrium range of the electron beam, the increase of sigma with the cutout size is linear. The percentage difference of the calculated PDD from the measured PDD for irregularly shaped cutouts was under 1.0%. Similar Result was obtained for four electron beam energies (6, 9, 12, and 15MeV).

Detection algorithm of ionospheric delay anomaly based on multi-reference stations for ionospheric scintillation

Radio waves including GPS signals, various TV communications, and radio broadcasting can be disturbed by a strong solar storm, which may occur due to solar flares and produce an ionospheric delay anomaly in the ionosphere according to the change of total electron content. Electron density irregularities can cause deep signal fading, frequently known as ionospheric scintillation, which can result in the positioning error using GPS signal. This paper proposes a detection algorithm for the ionosphere delay anomaly during a solar storm by using multi-reference stations. Different TEC grid which has irregular electron density was applied above one reference station. Then the ionospheric delay in zenith direction applied different TEC will show comparatively large ionospheric zenith delay due to the electron irregularity. The ionospheric slant delay applied an elevation angle at reference station was analyzed to detect the ionospheric delay anomaly that can result in positioning error. A simulation test was implemented and a proposed detection algorithm using data logged by four reference stations was applied to detect the ionospheric delay anomaly compared to a criterion.

SU‐E‐T‐403: Investigation of Electron Dose Calculation Using the Lateral Buildup Ratio Method

Purpose: To calculate the percentage depth dose of any irregular shape electron block using the lateral build‐up‐ratio method.Methods: Percentage depth dose (PDD) curves were measured using 6, 9, 12, and 15 MeV electron beam energies for applicator cone sizes of 6×6, 10×10, 14×14, and 20×20 cm2. Circular cutouts for each cone were prepared from 2.0 cm diameter to the maximum possible size for each cone. In addition, three irregular cutouts were prepared. The scanning was done using a water tank and two diodes ‐ one for the signal and the other a stationary reference outside the tank. The water surface was determined by scanning the signal diode slowly from water to air and by noting the sharp change of the percentage depth dose curve at the water/air interface.Results: The lateral build‐up‐ratio (LBR) for each circular cutout was calculated from the measured PDD curve using the open field of the 14×14 cm2 cone as the reference field. Using the LBR values and the radius of the circular cutouts, the corresponding lateral spread parameter (sigma) of the electron shower was calculated. The PDD curves of the irregular cutout sizes were calculated using the sigma values of the 2 cm and the 3 cm diameter cutout sizes. Finally, the calculated PDD curves were compared with measurements of the irregular cutouts Conclusions: The PDD curves for the irregular cutout calculated using the sigma value of the 2.0 cm diameter cutout agreed with the measured PDD curves within 2% for 6MeV and 4% for 12 MeV. On the other hand, using the average sigma values of the 2 and 3 cm diameter cutouts reduced the difference by a factor of two. The result of the calculated sigma value showed that at a given depth and energy, the sigma value increases with cutout size.

SU‐E‐T‐660: Does CMS XiO Electron Monte Carlo Model of a Siemens Artiste Linac Produce Accurate Dose Distribution for a Highly Irregular Electron Field?

Purpose: To evaluate the ability of CMS XiO Electron Monte Carlo algorithm (eMC) to accurately simulate irregularly shaped electron fields from a Siemens Artiste linear accelerator. Methods: Irregular electron fields where defined using a 1.5 cm thick Cerrobend cutout. For accuracy, the pattern was cut using a milling machine. eMC calculated planar dose distributions for 6, 9, 12, 15 and 18 MeV electron beams produced by Siemens Artiste linear accelerator were compared with measurements done with EBT Gafchromic films. All measurements and dose calculations were performed at the depth of maximum dose of the particular beam, at a standard SSD of 100 cm. The EBT films were scanned with Epson Perfection V7000 scanner. The red channel data of the 48 bit TIFF images was extracted, calibrated, corrected and analyzed with in‐house developed software. Results: The differences between eMC and the measurements were found to be within the gamma‐criteria of 2% dose and 2mm distance‐to‐agreement, including in the areas under the Cerrobend cutout. These differences decrease with increasing electron beam energy. Compared to the commonly used electron Pencil Beam algorithm, eMC produced significantly more accurate dose distributions for all regions of the irregular field, as well as under the cutout. Conclusions: The new CMS XiO eMC algorithm is capable of calculating dose distributions for highly irregular fields with an accuracy expected from photon beam calculation algorithms. Additional tests are under way to verify the performance of eMC for inhomogeneous medium and the calculation of dose output for a range of clinical electron fields.

SU-GG-T-100: Comparison of Measured D-Max for Irregular Electron Cutout Fields to Treatment Planning System Prediction and Nominal Open Field D-Max

Purpose: For irregular electron cutouts, not only output factors but also depths of maximum dose (D‐max) are often measured experimentally, increasing workload of clinical physicists and slowing clinical workflow. The purpose of this study is to investigate whether the D‐max of the corresponding open field or the D‐max of the cutout derived from the treatment planning system (TPS) can be used. Method and Materials: Seven cutouts for electron beams with energies ranging from 9 to 21 MeV were planned for patients using Pinnacle 8.0m without heterogeneity correction. To determine D‐max, the depth doses (PDDs) of these cutouts were generated in the TPS with flat‐surfaced water phantom geometry. PDDs were then compared with PDDs measured in a PTW scanning water phantom and corresponding open field PDDs. Because of the broad characteristic of PDDs near D‐max of these energy electron beams, a range of depths with PDD values > 99.5% on either side of D‐max were compared. Results: Within 0.5% dose variation, the D‐max ranges obtained from the TPS overlapped with those from measurements and nominal D‐max of open fields. For five of the seven cutouts, output factors measured at depths obtained from TPS, measurement, or corresponding open field resulted in less than 1% difference. For the other two cutouts, which showed the least overlap, less than 2% difference in output factors measured at the nominal depth of open‐field or measured Dmax was observed. Conclusion: For irregular electron cutouts, it is not necessary to measure the unique D‐max for the cutout field. Cutout factors within 2% measured at either nominal D‐max of the corresponding open field or the calculated D‐max from the treatment planning system can be achieved.

The fractal structure in the ionization dynamics of Rydberg lithium atoms in a static electric field

The ionization rate of Rydberg lithium atoms in a static electric field is examined within semiclassical theory which involves scattering effects off the core. By semiclassical analysis, this ionization process can be considered as the promoted valence electrons escaping through the Stark saddle point into the ionization channels. The resulting escape spectrum of the ejected electrons demonstrates a remarkable irregular electron pulse train in time-dependence and a complicated nesting structure with respect to the initial launching angles. Based on the Poincaré map and homoclinic tangle approach, the chaotic behaviour along with its corresponding fractal self-similar structure of the ionization spectra are analysed in detail. Our work is significant for understanding the quantum-classical correspondence.

SU‐FF‐T‐376: Electron Beam Dosimetry Using a 2D Detector Array:

Purpose: To adequately cover a target volume in electron beam radiation therapy, the radiation field size should be increased with respect to the geometric field settings. One could measure the dose distribution in the plane perpendicular to central axis at a depth of prescribed dose and increase the field size or simply change the prescribed isodose line for appropriate target coverage. In this study, lateral electron coverage is studied by using MapCheck a 2D diode array system. Method and Materials: Output factors, measured for 9 and 22 MeV electron beams by using MapCheck and 0.125 cm3 ion chamber on Varian IX (Linac) were compared. Set up geometry was kept the same. Dose calibration was performed for each electron beams and used in final dose measurement for MapCheck. Plans were performed on Eclipse planning system with 2×2 to 15×15cm2 for 9 and 22 MeV. Electron Monte Carlo was used for dose calculation and the plans were delivered on MapCheck and compared by using comparison criteria of 3% dose difference and 3 mm distance‐to‐agreement (DTA) within 10% isodose‐line threshold like IMRT dose verification. Results: Out put factors for 9 and 22 MeV measured for 2×2 to 15×15 cm2 with MapCheck and ion chamber agrees well within ±1.4%. Measured and planned dose comparisons for 9 MeV for 10×10 and 3×3 cm2 small insert shows very good agreement with passing rate of 98.4 and 97.8 % respectively. Conclusions: By measuring the dose profile at a prescribed depth one could easily verify the dose coverage to the target by measuring the lateral distance and also area covered by prescribed isodose line. MapCheck could also be used to measure the output factors for very small and irregular electron fields. Since MapCheck is commonly used in radiation therapy and it provides additional role in electron beam dosimetry.

Tracking filter for the mitigation of the ionospheric range bias

An extended Kalman filter (EKF) to estimate the ionospheric total electron content (TEC) along the radar line-of-sight has been developed. By varying the carrier frequency of consecutive radar pulses, it is shown that the TEC along the line-of-sight becomes observable and can be estimated in real-time to a high degree of accuracy. It is shown that the filtering formulation presented here optimally reduces the randomly varying range bias caused by the irregular electron density structure in the upper atmosphere. The performance of the tracking filter is examined with a Monte Carlo simulation analysis. It is shown that for a radar located in Thule, Greenland and operating at a nominal frequency of 435 MHz (UHF), an improvement of approximately 50% in the range estimation accuracy is achieved with a frequency separation of 18 MHz between two consecutive pulses. If the frequency separation is increased to 60 MHz, the increase in accuracy is 75%. It is also shown that in the absence of frequency separation, the performance of the tracking filter presented here reduces to that of a conventional six-state EKF that does not account for the ionospheric bias.

Effect of electron beam obliquity on lateral buildup ratio: a Monte Carlo dosimetry evaluation

The impact of the oblique electron beam on the lateral buildup ratio (LBR), used in the electron pencil beam model to predict the per cent depth dose (PDD) and dose per monitor unit (MU) for an irregular electron field, was examined using Monte Carlo simulation. The EGSnrc-based Monte Carlo code was used to model electron beams produced by a Varian 21 EX linear accelerator for different beam energies, angles of obliquity and field sizes. The Monte Carlo phase space model was verified by measurements using electron diode and radiographic film. For PDDs of oblique electron beams, it is found that the depth of maximum dose (dm) shifts towards the surface as the beam obliquity increases. Moreover, for increasing the beam angle of obliquity, the depth doses just beyond dm decrease with depth. The depth doses then increase eventually in a deeper depth close to the practical range. The LBRs and pencil beam radial spread function, calculated using PDDs with different field sizes, are found varying with electron beam energies, angles of obliquity and cutout diameters. It is found that LBR increases along the normalized depth when the beam angle of obliquity increases. This results in a decrease of the radial spread function with an increase of beam obliquity. When the size of the electron field increases, the variation of LBR with beam angle of obliquity decreases. It should be noted that when calculating dose per MU for an oblique electron beam with an irregular field misunderstanding and neglecting the effect of beam obliquity would lead to a significant deviation. A database of LBRs for oblique electron beams can be created using Monte Carlo simulation conveniently and is recommended when an oblique beam is used in electron radiotherapy.

A graphical user interface for an electron monitor unit calculator using a sector‐integration algorithm and exponential curve‐fitting method

A new electron monitor unit (MU) calculator program called “eMUc” was developed to provide a convenient electron MU calculation platform for the physics and radiotherapy staff in electron radiotherapy. The program was written using the Microsoft Visual Basic.net framework and has a user‐friendly front‐end window with the following features: (1) Apart from using the well‐known polynomial curve‐fitting method for the interpolation and extrapolation of relative output factors (ROFs), an exponential curve‐fitting method was used to obtain better results. (2) A new algorithm was used to acquire the radius in each angular segment in the irregular electron field during the sector integration. (3) A comprehensive graphical user interface running on the Microsoft Windows operating system was used. (4) Importing irregular electron cutout field images to the calculator program was simplified by using only a commercial optical scanner. (5) Interlocks were provided when the input patient treatment parameters could not be handled by the calculator database accurately. (6) A patient treatment record could be printed out as an electronic file or hard copy and transferred to the patient database. The data acquisition mainly required ROF measurements using various circular cutouts for all the available electron energies and applicators for our Varian 21 EX linear accelerator. To verify and implement the calculator, the measured results using our specific designed irregular and clinical cutouts were compared to those predicted by the calculator. Both agreed well with an error of ±2%.PACS number(s): 87.53.Fs; 87.53.Hv; 87.66.‐a

Ultrastructure of the male genital ducts of the clearnose skateRaja eglanteria

Tissues from the male genital ducts of six specimens of the clearnose skate Raja eglanteria, comprising the Leydig gland, upper and lower epididymis, ductus deferens and seminal vesicle, were fixed and embedded for ultrastructural examination. In the Leydig gland, two types of columnar cells were identified, one bearing microvilli, a basal nucleus and evidence of active secretion with plentiful endoplasmic reticulum and numerous secretory droplets, and the other pyriform with cilia, and swathes of cytofilaments emanating from prominent desmosomes. Occasional crystalloid intramitochondrial inclusions were seen in the first type, with a periodicity of 24 nm. The upper epididymis was composed of cuboidal cells with microvilli and cilia and irregular electron dense granules, some of which were basally situated and extremely large, often within cells resembling intraepithelial leucocytes; such cells were also seen in the stroma underlying the epithelium. The lower epididymis cells also bore microvilli and cilia and were heavily vacuolated with fatty inclusions as well as the granule-laden leucocytes seen previously. In the ductus deferens, cells had masses of long cilia with occasional microvilli; endoplasmic reticulum was well developed, forming complex arrays with sparse secretory droplets and basal mitochondria. In the seminal vesicle there were two cell types, the most common having long cilia and short microvilli and an occasional, paler cell with supranuclear accumulations of small, round mitochondria. These ultrastructural appearances have been related to cell glycosylation and functions including protein secretion, water absorption and waste removal, and illustrate how structure and function vary down the length of the genital tract.

SU-FF-T-308: Determination of Output, Percentage Depth Dose (PDD) and Effective Source to Skin Distance (SSDeff) for Irregular Electron Fields

Purpose: The sector integration method (SIM) has been described in the literature as a simple alternative to calculate the output for irregular electron fields. However, full characterization of the electron beam data (output and PDD) is necessary for the clinical use. The purpose of this work is to develop and commission new software using the SIM to calculate the output, PDD and SSDeff for irregular electron fields, compare the results with pencil beam algorithm calculation and measured data. Method and Materials: A Clinac 2300CD (Varian) with energies of 6, 9, 12, 15, 18 and 22 MeV was used. A set of circular electron cut‐outs, of different radios, were made for applicator sizes of 6×6 cm. and 15×15 cm. Measurements were done with a PTW Markus ionization chamber, an automatic phantom (Scanditronix‐Wellhofer) for PDD and a standard water phantom for output and SSDeff determination. Software was developed using Delphi 6.0. This software divides the irregular field in sectors (4, 8, 16, 32) and average the contribution for each one. A set of 15 cut‐outs (square, rectangular and irregular) were build for verification. For each cut‐out and electron energy the output, PDD and SSDeff were calculated with the new software and compared to chamber measurements. The treatment planning system (TPS) CadPlan (Varian) was used to calculate PDD. Results: The measured and calculated output differences for rectangular and squares fields were less than 1% and for irregular fields less than 3%. The PDD variations between measured and new software calculated were smaller than 2mm. The new software PDD agrees within 2mm with the TPS and ion chamber measurements, except for 6MeV were the differences were less than 3mm. Conclusion: The new software offers a simple and exact tool to calculate output and PDD curves for irregular electron fields with errors clinically acceptable.