Mr. Mohammad Matinfar Profile

Mohammad Matinfar

PhD student at Johns Hopkins Univ

SPIE Involvement:

Author

Publications (2)

Proceedings Article | 24 February 2010 Paper

Treatment planning and delivery of shell dose distribution for precision irradiation

Mohammad Matinfar, Santosh Iyer, Eric Ford, John Wong, Peter Kazanzides

Proceedings Volume 7625, 76252A (2010) https://doi.org/10.1117/12.838259

KEYWORDS: Tumors, Optical spheres, Radiation effects, Brain, Radiotherapy, Solids, Beam shaping, Calibration, Robotics, X-rays

Read Abstract +

Proceedings Article | 24 February 2010 Paper

Absolute vs. relative error characterization of electromagnetic tracking accuracy

Mohammad Matinfar, Ganesh Narayanasamy, Luis Gutierrez, Raymond Chan, Ameet Jain

Proceedings Volume 7625, 762524 (2010) https://doi.org/10.1117/12.844326

KEYWORDS: Sensors, Calibration, Environmental sensing, Electromagnetism, Error analysis, Optical tracking, Visualization, X-rays, Navigation systems, Phase measurement

Read Abstract +

Electromagnetic (EM) tracking systems are often used for real time navigation of medical tools in an Image Guided Therapy (IGT) system. They are specifically advantageous when the medical device requires tracking within the body of a patient where line of sight constraints prevent the use of conventional optical tracking. EM tracking systems are however very sensitive to electromagnetic field distortions. These distortions, arising from changes in the electromagnetic environment due to the presence of conductive ferromagnetic surgical tools or other medical equipment, limit the accuracy of EM tracking, in some cases potentially rendering tracking data unusable. We present a mapping method for the operating region over which EM tracking sensors are used, allowing for characterization of measurement errors, in turn providing physicians with visual feedback about measurement confidence or reliability of localization estimates. In this instance, we employ a calibration phantom to assess distortion within the operating field of the EM tracker and to display in real time the distribution of measurement errors, as well as the location and extent of the field associated with minimal spatial distortion. The accuracy is assessed relative to successive measurements. Error is computed for a reference point and consecutive measurement errors are displayed relative to the reference in order to characterize the accuracy in near-real-time. In an initial set-up phase, the phantom geometry is calibrated by registering the data from a multitude of EM sensors in a non-ferromagnetic ("clean") EM environment. The registration results in the locations of sensors with respect to each other and defines the geometry of the sensors in the phantom. In a measurement phase, the position and orientation data from all sensors are compared with the known geometry of the sensor spacing, and localization errors (displacement and orientation) are computed. Based on error thresholds provided by the operator, the spatial distribution of localization errors are clustered and dynamically displayed as separate confidence zones within the operating region of the EM tracker space.

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years