RECOMENDED READING:
• "Comparison of two commercial detector arrays for IMRT quality assurance"
  Jonathan G. Li,Guanghua Yan,and Chihray Liu
  JACMP, Volume 10, Number 2, Spring 2009
  
  
• "On the sensitivity of patient-specific IMRT QA to MLC positioning errors"
  Guanghua Yan, Chihray Liu, Thomas Simon, Lee-Cheng Peng, Christopher Fox, Jonathan Li
  JACMP, Volume 10, Number 1, Winter 2009
  
  
• "A study to establish reasonable action limits for patient specific quality assurance in intensity-modulated radiation therapy"
  Stefan Both, Ionut M. Alecu, Andrada R. Stan, Marius Alecu, Andrei Ciura, Jeremy M. Hansen, and Rodica Alecu
  JACMP, Volume 8, Number 2, Spring 2007
  
  
• "A survey on planar IMRT QA analysis"
  Benjamin E. Nelms and Jeff A. Simon
  JACMP, Volume 8, Number 3, Summer 2007
  
  
• "An Intercomparison Between Film Dosimetry and Diode Matrix for IMRT Quality Assurance"
  F. Banci Buonamici, etal
  Med. Phys.Volume 34, Issue 4, pp. 1372-1379, April 2007
  
  
• "Evaluation of a 2D diode array for IMRT quality assurance"
  Daniel Létourneau , Misbah Gulam , Di Yan , Mark Oldham and John W. Wong, Science Direct, 70(2) p199-206 2004
  
  
• "A 2-D diode array and analysis software for verification of intensity modulated radiation therapy delivery".
  P. Jursinic, etal, Medical Physics, 30(5) p870 2003
  
  

• "The use of a diode matrix in commissioning activities for electron energies
  >=9 MeV: A feasibility study"
  Valeria Casanova Borca, Massimo Pasquino, Franca Ozzello, and Santi Tofanib
  Medical Physics, Vol. 36, No. 4, pp. 1144 - 1154, April 2009
  
  
• "The use of film dosimetry of the penumbra region to improve the accuracy of intensity modulated radiotherapy"
  Mark R. Arnfielda, Karl Otto, Vijayan R. Aroumougame, and Ryan D. Alkins
  Med. Phys. Volume 32, Issue 1, pp. 12-18 (January 2005)
  
  
• "An analysis of tolerance levels in IMRT quality assurance procedures"
  Parminder S. Basran and Milton K. Woo
  Med. Phys.Volume 35, Issue 6, pp. 2300-2307, June 2008
  
  
• "Comparison of measured and computed portal dose for IMRT treatment"
  Savino Cilla, Pietro Viola, Luigi Azario, Luca Grimaldi, Maurizio Craus, Guido D’Onofrio, Andrea Fidanzio, Francesco Deodato,
  JACMP, Volume 7, Number 3, Summer 2006
  
  
• "Dose verification using a 2D diode array (Mapcheck) for electron beam modeling, QA and patient customized cutouts"
  Esmaeel Ghasroddashti , Stephen Sawchuk
  Departments of Physics and Engineering, London Regional cancer Program (pdf poster)
  
  
• "Feasibility of Using a 2D Diode Array System for Clinical Electron Beam Measurements"
  F.Q. Guo, C Wu1, R Stern1, C Luo1, T Liu1, J Shi2, C Yang1, J Purdy1
  University of California Davis Medical Center, Sacramento, CA, (2) Sun Nuclear Corporation, Melbourne, FL (pdf poster)
  
  
• "Direct Aperture Optimization Based Step-And-Shoot IMRT with Respiratory Gating"
  TU-E-ValB-06
  E Ahunbay, P Jursinic, and X A Li
  Med. Phys. 33, 2217 (2006)
  
  
• "Dependence of Planar IMRT QA On MLC Positional Inaccuracies"
  MO-D-224A-03
  E Ahunbay, P Jursinic, and XA Li
  Med. Phys. 33, 2167 (2006)
  
  
• "Use Of A 2D Array Of Diodes To Test The Accuracy Of MLC Leaf Position And Gap Width"
  SU-FF-T-442
  P Jursinic, K Kainz, E Ahunbay, and K Albano
  Med. Phys. 33, 2147 (2006)
  
  
• "Feasibility of Using a 2D Diode Array System for Clinical Electron Beam Measurements "
  SU-FF-T-242
  FQ Guo, C Wu, R Stern, C Luo, T Liu, J Shi, C Yang, and J Purdy
  Med. Phys. 33, 2103 (2006)
  
  
• "Dosimetric Comparison of a Semi-Conductor Array (MapCheck), EDR2 Film and Ion-Chamber in the Commissioning of Enhanced Dynamic Wedges On a Varian Linear Accelerator (21 EX) "
  SU-FF-T-181
  M Oh, H Malhotra, and M Podgorsak
  Med. Phys. 33, 2090 (2006)
  
  
• "An Alternative Calibration Method for Solid Modulator IMRT"
  SU-FF-T-84
  K Cashon and C Warner
  Med. Phys. 33, 2068 (2006)
  
  
• "A Planar Dose Calculation Algorithm for IMRT Quality Assurance"
  SU-FF-T-43
  G Yan, C Liu, B Lu, J Palta, and J Li
  Med. Phys. 33, 2059 (2006)
  
  
• "On the Dose Delivered to a Moving Target When Employing Different IMRT Delivery Mechanisms "
  TH-E-ValA-01
  E Ehler, Y Kim, N Arvidson, B Nelms, and W Tome
  Med. Phys. 33, 2296 (2006)
  
  
• "A Systematic Analysis of Patient Specific IMRT QA Data "
  TH-E-224A-02
  Z Su, H Jin, C Fox, H Li, B Lynch, C Yang, J Li, C Liu, J Palta, and S Kim
  Med. Phys. 33, 2291 (2006)
  
  
• "Proposed Pass/fail Criteria for IMRT Patient Specific QA "
  WE-D-224A-09
  C Yang, F Guo, C Wu, T Liu, J Perks, R Stern, and J Purdy
  Med. Phys. 33, 2248 (2006)
  
  
• "Is 0.5 Cm Leaf Width of MLC Beneficial in IMRT? "
  SU-FF-T-304
  Z Su, C Liu, J Li, C Yang, J Palta, and S Kim
  Med. Phys. 33, 2116 (2006)
  
  
• "Investigating Using IMRT Convert Parameter Settings to Improve the Agreement Between Planned and Delivered Dose Distributions "
  SU-FF-T-297
  D Robisch, M Davis, H Elson, M Lamba, and N Kumar
  Med. Phys. 33, 2115 (2006)
  
  
• "Commissioning Enhanced Dynamic Wedges Utilizing Mapcheck Device and Comparing with Film and Ion Chamber Dosimetry "
  SU-FF-T-134
  R Badkul and C Myers
  Med. Phys. 33, 2079 (2006)
  
  
• "Clinical Significance Based IMRT QA Approach"
  SU-FF-T-130
  J Lian, T Cullip, K Deschesne, and S Chang
  Med. Phys. 33, 2078 (2006)
  
  
• "A feasibility study of the Dynamic Phantom scanner for quality assurance of beam profiles at various gantry angles"
  Yunkai Zhang, Wen C. Hsi, James C.H. Chu, Damian B. Bernard, and Ross A. Abrams
  JACMP Volume 6, Number 2, Spring 2005
  
  
• "Feasibility of Using a 2D Diode Array System for Clinical Electron Beam Measurements"
  F.Q. Guo, C Wu, R Stern, C Luo, T Liu, C Yang, J Purdy from University of California Davis Medical Center, Sacramento, CA, and J Shi from Sun Nuclear Corporation, Melbourne, FL
  (Download Size 1072 kb)
  
  
• "Long-Term Reproducibility of IMRT Planning and Dosimetry Using Clinical Fields"
  Seng-Boh G. Lim, Thomas J. LoSasso, Margie A. Hunt, James G. Mechalakos, Chen-Shou Chui
  Memorial Sloan-Kettering Cancer Center, New York, NY, U.S.A
  (Download Size 134 kb)
  
  
• "KonRad IMRT verification with MapCHECK"
  Jack Yang, Chief Physicist, Radiation Oncology, Presented at 2005 AAPM conference, July 2005, Seattle, U.S.A
  (Download Size 129 kb)
  
  
• "IMRT QA with 2-Dimensional Diode Array of Detectors"
  Bhagat Ahluwalia, Daljit S. Saini. Presented at ICMP and silver Jubilee AMPI conference, October 2004, New Delhi, India
  (Download Size 129 KB)
  
  
• "Compensators: An alternative IMRT delivery technique"
  Sha X. Chang, Timothy J. Cullip, Katharin M. Deschesne, Elizabeth P. Miller, and Julian G. Rosenman1
  JACMP, COlume 5, Number 3, Summer 2004
  
  
• "Validation of dynamic MLC-controller log files using a two-dimensional diode array".
  J. G. Li, eatl, Medical Physics, 30(5) p799 2003
  
  
• "Symmetry of a Photon Beam at the Beginning of Exposure and Its Importance for IMRT".
  E. Lief, etal, New York University Medical Center, New York, NY, (TU-D-517A-02) 
  
  
• "Evaluation of a planar diode array for verification of IMRT Delivery".
  R. Miller, etal, Medical Physics, AbstractID 9360. 2003 AAPM, San Diego, CA
  

 

Q: Why does the MapCHECK use diode detectors?
A: Diode detectors have been the subject of much interest for their small size and instantaneous dose response.  Various dose response dependencies have been eliminated or minimized over the years and diodes are now a mature technology that offers several benefits over ionization chambers.  

The chief advantage of the MapCHECK detector over an ionization chamber is the 0.8 mm x 0.8 mm size of the MapCHECK detector.  It is widely known that small detectors give better pinpoint dose readings.  This is because the small size has less dose area to average into a single reading.  A MapCHECK detector is very small and the variation in dose intensity across it is statistically insignificant.  A chamber on the other hand is always going to be larger.  Even the very smallest chambers have an interior diameter of 2mm.  These chambers are double the MapCHECK detector size and are only available as a single detector, not as an array of 445 detectors.  Ionization chamber arrays use chambers that are even larger, specifically 5mm x 5mm x 4mm.  Within one of these chamber’s 25.0mm2 area the variation in dose intensity is much more significant – however the chamber is limited to return a single dose value – the average dose value.  This is extremely important for the measurement of highly modulated IMRT fields.  The ion chamber will average dose data across penumbra regions, offering artificially low values near the top of a gradient, and artificially high values at the bottom of a gradient.  The net result is a flattened penumbra.  The dose data returned by a MapCHECK detector is not averaged across the beam gradients and more accurately reflects the beam output with no flattening effect.  The detectors used in the MapCHECK array have even pointed out errors in the commissioning of planning systems with chambers that are too large. For up to date details on the importance of small detectors in measuring IMRT fields and penumbras, see: "The use of film dosimetry of the penumbra region to improve the accuracy of intensity modulated radiotherapy" M. Arnfield, etal, Medical Physics, 32(1) p12 2005
View Paper

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Q: Can the MapCHECK perform MLC QA?
A: The MapCHECK can perform efficient MLC QA by checking for the reproducibility of a delivered plan.  A delivered plan is a collection of many MLC movements w/ radiation between the movements.  If the movements are not right, the dose distribution will not be right.  Any saved measurement can be used as a QA template for MLC checks.  For instance, once a specific IMRT plan has been validated, there is a known pass rate based on the defined percent difference and distance-to-agreement criteria.  This creates a unique opportunity for future comparisons.  If the plan irradiated 411 detectors, and 97% pass with criteria of 3% difference and 3mm DTA, then if the same plan is delivered a week, month, or six months into the future the same results should be achieved.  Furthermore, the 3% of detectors that do not pass are illustrated and identified, and those same detectors should not pass during any future comparison.  Using this technique focuses on MLC QA from end to end.  Rather than evaluate the MLC leaf by leaf, this technique looks at the big picture.  As a means to further isolate problems that can be uncovered by running the reproducibility test described above, Sun Nuclear plans to include more specific and quantifiable MLC QA functions in the MapCHECK in the future. 

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Q: Is a gantry attachment available?
A: The MapCHECK can be mounted in the same gantry attachment that the PROFILER™ and Daily QA Check 2™ use.  This however limits the SSD to less than 100cm and does not allow for the proper build-up or rigidity needed for stringent IMRT QA.  A new Isocentric MapCHECK Gantry Attachment is available that holds the MapCHECK along with the proper build-up at 100cm SSD.  This is a robust fixture that is very rigid, which makes it an excellent tool for checking sag and performing other Isotropic tests.

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Q: Are composite measurements supported by the MapCHECK?
A: The belief that the verification of individual beams is a more stringent test than composite beams is widely supported.  However, composite measurements where the beam axis is perpendicular to the MapCHECK detector array are supported by the MapCHECK.   With the MapCHECK on the treatment couch, you can instruct the planning system to keep the gantry angle fixed during all fields, and execute all fields during one MapCHECK measurement.  Alternatively, you can use the Isocentric MapCHECK Gantry Attachment to deliver the beams with the MapCHECK mounted in the gantry at the proper depth and SSD.  Either method would require you to import the corresponding composite QA plan and compare.

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Q: What type of cable is used with the MapCHECK?
A: The MapCHECK uses the same cable and power supply as other Sun Nuclear instruments. 

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Q: What Treatment Planning Systems (TPS) will be supported?
A: All major Treatment Planning Systems are supported. If you have a custom or unusual planning system, please contact Sun Nuclear and we will attempt to accommodate your system. We have already written interfaces to several custom systems.

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Q: How is the MapCHECK calibrated?
A: Array calibration is performed with a built-in software application that guides the user through Sun Nuclear’s wide field calibration (US Patent # 6125335.) Six separate exposures calibrate the entire detector array using detector substitution.  Calibration takes about 15 minutes per energy.  Published papers suggest the average clinic will need to recalibrate their MapCHECK array about once per year.

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Q: Can MapCHECK be used to measure the absolute dose?
A: Yes. Dose calibration is performed in a 10 x 10 field with the array at a depth where the dose is known. This establishes a dose calibration factor on the center detector, which is then transferred to the other array detectors via the sensitivity correction factors that are relative to the center detector.  Absolute dose can be calibrated for as often as is desired and takes about 25 seconds. 

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Q: The MapCHECK compares IMRT treatment plans without film. Is film required for reimbursement?
A: No. From the ACR Bulletin, April 2001, Volume 57, Issue 4, titled New Intensity-modulated Radiation Therapy Codes for Hospital Outpatient Procedures: "The accuracy of dose delivery must be documented for each coarse of treatment by irradiating a phantom that contains either calibrated film to sample the dose distribution or an equivalent measurement system to verify that the dose delivered is the dose planned."

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