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ELECTRONIC READOUT FOR A CCD-VIDEO BASED EPID

IP.com Disclosure Number: IPCOM000010151D
Publication Date: 2002-Oct-25
Document File: 3 page(s) / 3M

Publishing Venue

The IP.com Prior Art Database

Related People

Farhad A. Ghelmanasai: AUTHOR

Abstract

The following patent describes a new control protocol or electronic readout for a CCD or camera based EPID which introduces Single mode or snap shot imaging for low MU (patient positioning), Continuous external trigger mode for IMRT , movie and verification imaging, Linear accelerator artifacts removal, and also a stable, accurate dosimetric measurements and linearity with the dose rate.

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ELECTRONIC READOUT FOR A CCD-VIDEO BASED EPID

Farhad A. Ghelmanasai

SIEMENS

SUPPLEMENTAL SHEET FOR INVENTION DISCLOSURE

Our Ref: 2002E12268US

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ABSTRACT

Electronic Readout for a CCD - Video Based EPID

The following patent describes a new control protocol or electronic readout for a CCD or camera based EPID which introduces Single mode or snap shot imaging for low MU (patient positioning), Continuous external trigger mode for IMRT , movie and verification imaging, Linear accelerator artifacts removal, and also a stable, accurate dosimetric measurements and linearity with the dose rate.

Single Mode - Low Dose Imaging: This mode is used for patient positioning (including cone beam reconstruction). In this mode sensors integrate the signal during the radiation period and the readout is performed after elapse of radiation. The camera is in SnapshotExternal pulse width mode, and the trailing edge (or leading edge) of the trigger signal or Rad-On signal will activate the Horizontal Drive (HD) and begins the exposure.

Deactivating the trigger or Rad-On signal will acti\.ate the HD and this means end of exposure. After exposure ends, the Write Enable (\\fE) will be activated and a frame readout occurs (Figure I ).

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Figure-1. Single Mode (for Cohu 7500)

In above mode the sensors are not forced to be discharged prior to the start of trigger siœnal and the residual data on the sensors (before the start of radiation) \..'ill contribute to the single mode image. In order to force sensors discharœe ",.ith pulse ""idth trigger

mode, a preRad-on signal is used for trigger signal and with the start of trigger the sensors are forced to be discharged prior to the start of radiation (Figure 2)- The preRadOn for a camera with the timing of Figure 2 should occur 7ms prior to Rad-on-

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Figure-2- Single Mode ~-ith Forced Sensor Discharge

. Continuous Modc- Hil!h Dosc Imal!inl!: This mode is mainl). used for monitoring the patient during the treatment and includes the mo\-ie im...