Commissioning Data Research Articles

Sessional Urgent Dental Care Flexible Commissioning Data Tool: describing health outcomes through intelligent data

Sessional Urgent Dental Care Flexible Commissioning Data Tool: describing health outcomes through intelligent data

Adjustment of a crustal geoelectric model from Commissioning data of HVDC ground electrodes: A case study from the Northeastern Paraná Basin, Brazil

Small-scale near-surface galvanic scatters are known to be a bane when using natural field EM data to get quantitative information about the subsurface resistivity structure. Specifically, on magnetotelluric measurements, the effect of local surficial inhomogeneities is almost inevitable and produces a static shift in the measured apparent resistivities over the whole range of sampled frequencies. We present here the methodology used to account for static shift effects and make a correct interpretation of the resistivity distribution in a region beneath the northeastern part of the volcanic-covered Paraná basin, SE Brazil. Within this region are located the ground electrodes of the Rio Madeira HVDC transmission system (Bipoles I and II). The available data includes geophysical soundings made for the electrodes site selection before their installation and data acquired in the subsequent commissioning measurements after their construction (electrode resistance, soil surface potentials and pipe-to-soil potentials). Iterative calculations for the simultaneous adjustment of the measured electrode resistance and the local geoelectric model were developed, based on the commissioning data of the electrode. The accuracy of the adjusted geoelectric model was confirmed by the excellent fit obtained for the measured and calculated pipe-to-soil potentials at Gasbol, the Bolivia-Brazil gas pipeline located 26 km away from the electrode.

Differences in access and utilisation of mental health services in the perinatal period for women from ethnic minorities\u2014a population-based study

BackgroundBarriers to accessing mental health care during pregnancy and the first postnatal year (perinatal period) seem to be greater for ethnic minority women; however, there is no reliable large-scale data about their actual use of mental health services during this period. Our study aims to explore access rates to secondary mental health services, including involuntary admissions to psychiatric inpatient care and patterns of engagement for ethnic minority women aged 18+ who gave birth in 2017 in England, UK.MethodsTwo datasets from the National Commissioning Data Repository, the Acute Inpatient Dataset and Mental Health Services Dataset, were linked. Datasets covering the full perinatal period for each woman were included. Rates were standardised by age and deprivation.ResultsOut of 615,092 women who gave birth in England in 2017, 22,073 (3.5%) started a contact with mental health services during the perinatal period. In total, 713 (3.2%) were admitted to inpatient care, and 282 (39.5%) involuntarily. Ethnicity data was available for 98% of the sample. Black African, Asian and White Other women had significantly lower access to community mental health services and higher percentages of involuntary admissions than White British women. Black African, Asian and White Other women had a higher number of attended community contacts and fewer non-attendances/cancellations of appointments than White British women.ConclusionAccess to mental health services during the perinatal period varies significantly between women from different ethnic groups. Access to community mental health services should be facilitated for Black African, Asian and White Other women during the perinatal period, which may reduce rates of involuntary hospital admissions for these groups. The pattern of engagement with community services for women from these ethnicities indicates that access appears to be a problem rather than utilisation.

The first neutron time-of-flight line in Spain: Commissioning and new data for the definition of a neutron standard field

The National Accelerator Laboratory (CNA) has developed the first accelerator line in Spain devoted to the measurement of cross sections involving neutrons by means of the time-of-flight technique. For neutron generation, pulsed proton beams with 1 nsec pulse width and with variable repetition rates are delivered. The data acquisition has been built using a CAEN Digitizer. The aim of this work is to demonstrate the good performance of the time-of-flight system. The commissioning of the line has consisted of the measurement of the neutron field generated by protons at 1912 keV impinging on a thick lithium target. Such a field has been extensively used in nuclear astrophysics since 1988. Recently, there have been experimental works with the goal to support it as a standard neutron field. The results show the good performance of the time-of-flight system and also support its possible definition as a standard.

Technical Note: Dosimetric characteristics of the ocular beam line and commissioning data for an ocular proton therapy planning system at the Proton Therapy Center Houston.

To systematically analyze and present the properties of a small-field, double-scattering proton beam line intended to be used for the treatment of ocular cancer, and to provide configuration data for commission of the Eclipse Ocular Proton Planning System. Measurements were made using ionization chambers, diodes, and films to determine dose profiles and output factors of the proton beams of the beam line at the Proton Therapy Center Houston. In parallel, Monte Carlo simulations were performed to validate the measured data and to provide additional insight into detailed beam parameters that are hard to measure, such as field size factors and a comparison of output factors as a function of circular and rectangular fields. The presented data comprise depth dose profiles, including distal and proximal profiles used to configure the Eclipse Ocular Proton Planning system, distal fall-off widths, lateral profiles and penumbrae sizes, as well as output factors as a function of field size, SOBP width, range shifter thickness, snout position, and source-to-surface distance. We have completed a comprehensive characterization of the beam line. The data will be useful to characterize proton beams in clinical and experimental small-field applications.

Beam Commissioning Data Acquisition for the Iris Variable Aperture Collimator of CyberKnife VSI

Objective: To minimize the risk inherent to the use of medical radiation and robotic radiosurgery, this research introduced the basis and method of beam commissioning data acquisition for the Iris variable aperture collimator of CyberKnife VSI. Methods: In this study, clinical dosimetry measurements of the Iris collimator such as tissue-phantom ratios (TPRs), off-center ratios (OCRs), and secondary collimator output factors (OFs) were conducted, and the data was contrasted with that of the Fixed collimator. Results: The Iris data and the Fixed data were not quite different in TPRs in the same radiation field size. Since the difference of the hardware structure,the OCRs and OFs were quite different, especially in small aperture (5, 7.5 and 10 mm) under the same condition of SAD. For example, the maximum discrepancy of the OFs was 26.67% (5mm aperture, 650mm SAD). Conclusion: When Iris aperture makes some change, tungsten segments move fast and form an aperture smaller than that we need, and then recover to the right size, which may affect the results of the measurement, and also the dodecagonal design of Iris results in a problem of leakage radiation on the edge. Keywords: Beam commissioning, Iris Variable Aperture Collimator, tissue phantom ratio, off center ratio, output factor, CyberKnife VSI™.

Commissioning an Elekta Versa HD linear accelerator.

The purpose of this study is to report the dosimetric aspects of commissioning performed on an Elekta Versa HD linear accelerator (linac) with high‐dose‐rate flattening filter‐free (FFF) photon modes and electron modes. Acceptance and commissioning was performed on the Elekta Versa HD linac with five photon energies (6 MV, 10 MV, 18 MV, 6 MV FFF, 10 MV FFF), four electron energies (6 MeV, 9 MeV, 12 MeV, 15 MeV) and 160‐leaf (5 mm wide) multileaf collimators (MLCs). Mechanical and dosimetric data were measured and evaluated. The measurements include percent depth doses (PDDs), in‐plane and cross‐plane profiles, head scatter factor (Sc), relative photon output factors (Scp), universal wedge transmission factor, MLC transmission factors, and electron cone factors. Gantry, collimator, and couch isocentricity measurements were within 1 mm, 0.7 mm, and 0.7 mm diameter, respectively. The PDDs of 6 MV FFF and 10 MV FFF beams show deeper dmax and steeper falloff with depth than the corresponding flattened beams. While flatness values of 6 MV FFF and 10 MV FFF normalized profiles were expectedly higher than the corresponding flattened beams, the symmetry values were almost identical. The cross‐plane penumbra values were higher than the in‐plane penumbra values for all the energies. The MLC transmission values were 0.5%, 0.6%, and 0.6% for 6 MV, 10 MV, and 18 MV photon beams, respectively. The electron PDDs, profiles, and cone factors agree well with the literature. The outcome of radiation treatment is directly related to the accuracy in the dose modeled in the treatment planning system, which is based on the commissioned data. Commissioning data provided us a valuable insight into the dosimetric characteristics of the beam. This set of commissioning data can provide comparison data to others performing Versa HD commissioning, thereby improving patient safety.PACS number(s): 87.56.bd

SU‐E‐T‐190: Commissioning An Elekta VersaHD Linear Accelerator

Purpose:The purpose of this study is to report the dosimetric aspects of commissioning performed on an Elekta VersaHD linear accelerator with high dose rate flattening‐filter‐free (FFF) photon modes and electron modes.Methods:Acceptance and commissioning was performed on an Elekta VersaHD linac with 5 photon energies (6MV, 10MV, 18MV, 6FFF, 10FFF), 4 electron energies (6MeV, 9MeV, 12MeV, 15MeV) and 160 leaf (5mm wide) multi‐leaf collimators (MLCs). Mechanical and dosimetric data was measured and evaluated. The measurements include percent depth doses (PDDs), inplane and crossplane profiles, head scatter factor (Sc), relative photon output factors (Scp), universal wedge transmission factor, MLC transmission factors, and electron cone factors.Results:Gantry, collimator, couch isocentricity measurements were within 1mm, 0.7mm and 0.7mm diameter respectively. The PDDs of 6FFF and 10FFF beams show deeper dmax and steeper fall‐off with depth than the corresponding flattened beams. While flatness values of 6FFF and 10FFF normalized profiles were higher than the corresponding flattened beams, the symmetry values were almost identical. The crossplane penumbra values were higher than the inplane penumbra values for all the energies. The MLC transmission values were 0.5%, 0.6% and 0.6% for 6MV, 10MV, and 18MV photon beams. The electron PDDs, profiles and cone factors is validated by literature.Conclusion:The outcome of radiation treatment is directly related to the accuracy in the dose modeled in the treatment planning system which is based on the commissioned data. Commissioning data provided us a valuable insight into the dosimetric characteristics of the beam. This set of commissioning data can provide comparison data to others performing VersaHD commissioning thus improving patient safety.

SU-E-T-324: Multi-Institution Comparison for TrueBeam Commissioning Data and Beam Modeling Verification Using An Anisotropic Analytical Algorithm

Purpose: To perform a dosimetric comparison of TrueBeam(TB) commissioning data between UAMS and other institutions; verify the beam modeling accuracy. Methods: Dosimetric data including percentage depth dose (PDD), penumbra, mlc transmission leakage(TL) and dosimetric leaf gap(DLG) for 6MV, 6MV FFF, 10MV and 10MV FFF X-ray beams were compared with two published papers (Chang et.al (Publication #1) and Jan et.al (Publication #2)). The beam modeling accuracy was evaluated by comparing the PDD, absolute point dose and patient dose from Eclipse TPS calculation using AAA algorithm and from measurements. Point dose was measured using calibrated ion chambers of different sizes at different depths, different field sizes for all four energies. Patient IMRT and VMAT doses were verified using PTW Octavius ion chamber and SunNuclear ArcCheck diode array. Results: The comparison of UAMS TB commissioning data with published data shows that the differences for PDDs are within 1% except for 10MV FFF beam, where the maximum difference is within 3% as compared with Publication #2. The differences for penumbra are within 1mm for all four energies. At UAMS, the mlc TL and DLG are 1.21% and 0.45mm for 6MV; 1.02% and 0.348mm for 6MV FFF; 1.39% and 0.545mm for 10MV; and 1.2% and 0.484mm for 10MV FFF beams respectively. These results are in good agreement with those from the other two institutions. For Eclipse beam modeling evaluation, all point dose measurements are within 3% compared with the Eclipse TPS calculation except for the 1.0 cm2 field size, where the maximum difference is 5%. All patient QAs were acceptable with a gamma agreement index score of 95% or higher based on the 3%, 3mm criteria. Conclusion: Commissioning data for the UAMS TB was clinically identical with the published data from two other institutions. The beam modeling verification shows that Eclipse modeling of these four beams is accurate.

SU-E-T-45: Can We Model Proton Beam Output Factors Accurately without Measurements?

Purpose: Currently, no commercial protontreatment planning systems have been FDA‐approved for Monitor Unit (MU) prediction. Patient and field specific MU numbers and output factors are therefore determined by either measurements or in‐house modeling. The purpose of this project is to assess the modeling accuracy and determine in which cases measurements are necessary. Methods: We developed an in‐house analytical model to predict output factors for patient specific proton fields, taking into account the effect of proton range, modulation width, and field size on the dose output. A refined model, which incorporated more commissioning data and accounted for the effects of scanning area and field size, was developed later and retrospectively applied to the fields. Model‐predicted and measured output factors were compared for 1074 proton fields. Causes for the differenceswere analyzed for differences of 2.5% or more, which would be used for future improvement and determine in which cases where measurements are needed. Results: For the 1074 patient fields we analyzed, the refined model predicted output factors within 2% for 91.6% of fields, 2.5% for 96.9% for fields, and 3% for 99.7% of fields, compared to 85.2%, 93.6 and 98.2% respectively for the old model. Large differences between modeling and measurements (>2.5%) typically occurred for shallow range, large modulation, and/or irregular shaped proton fields. Causes for differences were analyzed, which mainly include dose rate dependence, off axis fields, data interpolation, and snout position effects. Conclusion: The study demonstrated that the analytical model can predict output factors accurately for most patient specific proton fields. For over 90% of proton fields, measurements may not be necessary, thus improving work flow and saving valuable proton beam time. It is possible to further improve modeling accuracy by incorporating more commissioning data, dose rate effects and other factors into the output factor model.

SU-E-T-629: Dosimetric Effect of Different Commissioning Data on the SBRT of Small Lung Tumors

Purpose: To investigate the dosimetric effect of different linac commissioning data on the stereotactic body radiation therapy(SBRT) of small lungtumors. Methods: Small‐sized scanning ion chambers such as CC13 and CC04 (IBA Dosimetry) are commonly used to collect beam data for TPS commissioning. However, their volume‐averaging effect is non‐ negligible. Their dosimetric effect on the SBRT of lungtumors was investigated by commissioning the TPS (Pinnacle ver. 9.0) using CC13 and CC04 scanned beam data and compared with the beam model using a diode scanned beam data. Treatment plans were generated for 6 SBRT of lungtumors using each beam model, with a dose grid of 4×4×4 mm3. An additional plan for each case was generated using the diode model with a dose grid of 2×2×2 mm3 and served as the standard. Six to eight conformal coplanar fields using 6 MV photon beams were used for all the plans. PTV volumes ranged from 15.7 cc to 86.1 cc, with the average dimensions ranged from 2.2 cm to 5.2 cm. Important dosimetric parameters, including target coverage, conformal index, and normal structure sparing, were evaluated. Differences of more than 5% were considered significant. Results: Significant differences were seen among plans with different beam models. Differences in PTV coverage of up to 10% were seen, and differences in conformal indices were up to 23%. Significant differences were also seen in normal organ sparing, including the lung and chest wall. In general, the smaller the PTV was, the larger the difference. Dose grid of 4×4×4 mm3 was found to be adequate, resulting in less than 3% difference in most cases when compared with the standard. Conclusions: For SBRT of lungtumors, it is important to minimize the volume‐averaging effect of the beam data used for TPS commissioning to ensure consistent results.

SU‐GG‐T‐307: Multi‐Institution Comparison of Varian Linac Electron Commissioning Data: Application to Eclipse Generalized Gaussian Pencil Beam Algorithm Commissioning

Purpose: To point out clinically relevant issues in the commissioning process of the Eclipse Generalized Gaussian Pencil Beam (GGPB) algorithm and to post a multi‐institution comparison of Varian linac electron commissioning data. Research was performed to quantify the accuracy of commissioning a treatment planning system using either Varian “golden beam data” or common data for several linacs. Using such data may be a useful option for clinics installing or replacing a linac, with the need to make the transition with minimal down time. This work seeks to address whether or not such techniques are clinically acceptable. Method and Materials: Graphical techniques were used to compare the electron commissioning data from multiple independent Varian linacs. The performance of the Varian “golden beam data” for beam modeling using the Eclipse GGPB algorithm was examined by comparing calculations to measured dose distributions as well to calculations made with a fully commissioned pencil beam algorithm in CMS Xio. Results: Depth dose curves from the various independent linacs were typically found to be within a 3 mm distance to agreement, with the Varian “golden beam data” falling within an approximate 5 mm distance to agreement. Comparisons between CMS Xio and Eclipse showed that Eclipse depth dose profiles are less smooth and tend to contain calculation algorithm artifacts. Conclusion: Although good agreement was found between the commissioning data of the clinics in this study, special care should be taken when using data from another linac to commission a treatment planning system. With careful adjustment of the modeling parameters in the treatment planning systems it may be possible to achieve calculation accuracy that is within a clinically acceptable tolerance. However, if optimal accuracy is desired, a full set of commissioning data should be collected for the specific linac being modeled.

SU‐FF‐I‐129: A Comprehensive QA Program for Radiotherapy MR Simulators

Purpose: To our knowledge, there are no publications on the acceptance, commissioning and quality assurance (QA) procedures for MR simulators in radiotherapy. The purpose of this work is to develop a comprehensive protocol for MR simulators in radiotherapy. Materials and Method: A GE 1.5T MR scanner was installed in our department in 2006. During acceptance testing and commissioning, the MR scanner was tested according to the standards established by the American College of Radiology (ACR) MRI Accreditation Program. An ACR phantom was used for the study. Our QA protocol includes procedures for geometric accuracy, high‐contrast spatial resolution, slice thickness accuracy, slice position accuracy, image intensity uniformity, percent signal ghosting, low‐contrast object detectability, inter‐slice RF interference, fringe field survey, magnetic field homogeneity, eddy currents, coils SNR check and cryogen consumption. We also checked the patient/console intercom 2464_3 2464_4 system, table stop buttons, emergency stop button, table docking, vertical movement, alignment lights and the ventilation system. Monthly QA were developed to check the RF, transmission gain/attenuation, imaging distortion and resolutions using the ACR phantom. A phantom from GE was used for daily QA to check the SNR, RF, isocenter position and the gradients. The lasers installed in the MR room for patient setup were also checked. QA procedures were developed for MR spectroscopy. The results from monthly and daily QA were compared with the commissioning data. Results: The acceptance/commissioning test and monthly QA showed that the MR scanner met the criteria established by the ACR MRI Accreditation Program. The results from the daily QA are SNA: 29.66±0.84; Noise: 2.31±0.1, CTR Frequency: 63860229±4778; iso‐Z: 8916.33±9.26; Gradient X, Y and Z: 100.14±0.11; 100.05±0.08; and 99.8±0.10, respectively, for >2 years. The variations were within 1% of the commission data. Conclusions: A comprehensive QA protocol was developed and routinely used for our MR simulator for radiotherapy.

Track-based alignment of the ATLAS inner detector

ATLAS is a general purpose experiment currently under final assembly for the Large Hadron Collider at CERN. The Inner Detector is the ATLAS internal tracker. It comprises different complementary technologies for tracking purposes: silicon and straw tubes gaseous detectors. In order to reach the optimal performance of the tracker, a high-precision alignment of the huge number of detecting elements is required. Several track-based alignment algorithms have been developed for the Inner Detector. An extensive validation has been performed with simulated events and real data coming from the ATLAS Combined Testbeam and data-taking of cosmic rays on surface. This paper reports on the principle of the different methods, computing requirements and results obtained with real data. Finally, preliminary results from the ATLAS Computing System Commissioning and Calibration Data Challenge are shown.

PanDA: distributed production and distributed analysis system for ATLAS

A new distributed software system was developed in the fall of 2005 for the ATLAS experiment at the LHC. This system, called PANDA, provides an integrated service architecture with late binding of jobs, maximal automation through layered services, tight binding with ATLAS Distributed Data Management system [1], advanced error discovery and recovery procedures, and other features. In this talk, we will describe the PANDA software system. Special emphasis will be placed on the evolution of PANDA based on one and half year of real experience in carrying out Computer System Commissioning data production [2] for ATLAS. The architecture of PANDA is well suited for the computing needs of the ATLAS experiment, which is expected to be one of the first HEP experiments to operate at the petabyte scale.

SU‐GG‐T‐134: Dosimetric Verification of Dose Calculation Algorithms for IMRT Treatment Plan

Purpose: The purpose of this study was to determine the accuracy of dose calculation in penumbra region from two different commercial IMRT treatment planning systems (TPS). The accuracy of IMRT calculations with a convolution/superposition and a pencil‐beam algorithm was tested using commission data with the modified values from Gaussian fitting approaches the real doses to correct for the spatial response of finite‐sized ionization chamber against measurement. Method and Materials: The IMRT head and neck phantom used in this study was housed in a custom‐designed package for efficient evaluation of the measured doses with different materials and various detectors. The Varian 21EX linear accelerator with 6 MV beam was used. The Pinnacle and the Ecilpse TPSs were calculated based on commissioning data that included beam profiles collected with a 0.125 cm3 ionization chamber. We have modified the commissioning data by a Gaussian function of an ionization chamber kernel to the real profile. Dose measurements made by ionization chamber, and glass dosimeter positioned within the phantom's target insert were compared with the calculated doses. Results: The differences for these algorithm results in average PTV doses were within 1.0%. Ionization chamber results showed approximately 1.7% better agreement than the glass dosimeters and the differences between measured and calculated doses were more than 3.0% for both algorithms. However, calculations using these algorithms after it were re‐commissioned from Gaussian fitting gave better agreement with measurements of IMRT field. A main reason of these results was attributed to detector size effects in the commissioning data. Conclusion: These results show that accurately measuring the penumbra region improves the accuracy of the dose calculations predicted by the TPS and thus is important to choose an appreciate detector.

SU‐GG‐T‐168: Measurement Errors Associated with Linear Accelerator Commissioning Data

Purpose: Linear accelerator (LINAC) commissioning employs 3‐D water phantoms (WP) to accurately assess LINAC dosimetric characteristics. The accuracy of the treatment planning system (TPS) modeling is based on the collected data. This investigation aims to assess the errors associated with the collection of commissioning data. Method and Materials: Possible sources of error within 3‐D WP measurements that were assessed are water tank mechanics, data acquisition, and chamber aspects. WP scanning software, mechanical measurements, and infra‐red motion tracking cameras were used to evaluate the mechanical performance of the WP. Continuous motion and point by point measurements were compared for a variety of standard detectors. Minor field size variations were scaled to the nominal field size for TPS import purposes using two methods, 1) geometric scaling of the whole profile or 2) geometric scaling of 80% of the field width. The detector orientation effects were evaluated for profiles and percentage depth dose. Results: WP positional accuracy and reproducibility was within 0.4mm and mechanical hysteresis within 0.46mm. The collection method impacted the results obtained for small detectors (<0.01cc) with the point measurement technique resulting in reduced noise level. However, the time scale increased considerably with the point by point technique. For field width scaling the 80% scaling method showed improved results compared to scaling the whole profile. The detector orientation showed variations in the build up region for small detectors and small variations were observed for penumbral widths of profile measurements. Conclusion: Error sources in data collection have been identified and quantified in this work. Detailed error analysis of experimental set up is presented.This work supported in part with Federal funds from the National Cancer Institute, Contract No HHSN261200522014C, and by Sun Nuclear Corporation.

The characterization of unflattened photon beams from a 6 MV linear accelerator

Commissioning data have been measured for an Elekta Precise linear accelerator running at 6 MV without a flattening filter with the aim of studying the effects of flattening filter removal on machine operation and beam characterization. Modern radiotherapy practice now routinely relies on the use of fluence modifying techniques such as IMRT, i.e. the active production of non-flat beams. For these techniques the flattening filter should not be necessary. It is also possible that the increased intensity around the central axis associated with unflattened beams may be useful for conventional treatment planning by acting as a field-in-field or integrated boost technique. For this reason open and wedged field data are presented. Whilst problems exist in running the machine filter free clinically, this paper shows that in many ways the beam is actually more stable, exhibiting almost half the variation in field symmetry for changes in steering and bending currents. Dosimetric benefits are reported here which include a reduction in head scatter by approx. 70%, decreased penumbra (0.5 mm), lower dose outside of the field edge (11%) and a doubling in dose rate (2.3 times for open and 1.9 times for wedged fields). Measurements also show that reduced scatter also reduces leakage radiation by approx. 60%, significantly lowering whole body doses. The greatest benefit of filter-free use is perceived to be for IMRT where increased dose rate combined with reduced head scatter and leakage radiation should lead to improved dose calculation, giving simpler, faster and more accurate dose delivery with reduced dose to normal tissues.

A Catalog of Compact Groups of Galaxies in the SDSS Commissioning Data

Compact groups (CGs) of galaxies--relatively poor groups of galaxies in which the typical separations between members is of the order of a galaxy diameter--offer an exceptional laboratory for the study of dense galaxian environments with short (<1Gyr) dynamical time-scales. In this paper, we present an objectively defined catalog of CGs in 153 sq deg of the Sloan Digital Sky Survey Early Data Release (SDSS EDR). To identify CGs, we applied a modified version of Hickson's (1982) criteria aimed at finding the highest density CGs and thus reducing the number of chance alignments. Our catalog contains 175 CGs down to a limiting galaxy magnitude of r* = 21. The resulting catalog has a median depth of approximately z = 0.13, substantially deeper than previous CG catalogs. Since the SDSS will eventually image up to one quarter of the celestial sphere, we expect our final catalog, based upon the completed SDSS, will contain on the order of 5,000-10,000 CGs. This catalog will be useful for conducting studies of the general characteristics of CGs, their environments, and their component galaxies.

The Millennium Galaxy Catalogue: 16 ≤BMGC&lt; 24 galaxy counts and the calibration of the local galaxy luminosity function

The Millennium Galaxy Catalogue (MGC) is a 37.5 deg 2 , medium-deep, B-band imaging survey along the celestial equator, taken with the Wide Field Camera on the Isaac Newton Telescope. The survey region is contained within the regions of both the Two Degree Field Galaxy Redshift Survey (2dFGRS) and the Sloan Digital Sky Survey Early Data Release (SDSS-EDR). The survey has a uniform isophotal detection limit of 26 mag arcsec - 2 and it provides a robust, well-defined catalogue of stars and galaxies in the range 16 ≤ B M G C < 24 mag. Here we describe the survey strategy, the photometric and astrometric calibration, source detection and analysis, and present the galaxy number counts that connect the bright and faint galaxy populations within a single survey. We argue that these counts represent the state of the art and use them to constrain the normalizations (Φ*) of a number of recent estimates of the local galaxy luminosity function. We find that the 2dFGRS, SDSS Commissioning Data (CD), ESO Slice Project, Century Survey, Durham/UKST, Mt Stromlo/APM, SSRS2 and NOG luminosity functions require a revision of their published Φ* values by factors of 1.05 ′ 0.05, 0.76 ′ 0.10, 1.02 ′ 0.22, 1.02 ′ 0.16, 1.16 ′ 0.28, 1.75 ′ 0.37, 1.40 ′ 0.26 and 1.01 ′ 0.39, respectively. After renormalizing the galaxy luminosity functions we find a mean local b J luminosity density of j b J = (1.986 ′ 0.031) x 10 8 h L O . Mpc - 3 . 1 .