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Med Phys. 2012 Jul;39(7):4155-66. doi: 10.1118/1.4725710.

A combined dose calculation and verification method for a small animal precision irradiator based on onboard imaging.

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Department of Radiation Oncology, Maastricht University Medical Center, Maastricht, The Netherlands.



Novel small animal precision microirradiators (micro-IR) are becoming available for preclinical use and are often equipped with onboard imaging (OBI) devices. We investigated the use of OBI as a means to infer the accuracy of the delivered treatment plan.


Monte Carlo modeling of the micro-IR including an elliptical Gaussian electron beam incident on the x-ray tube was used to score dose and to continue photon transport to the plane of the OBI device. A model of the OBI detector response was used to generate simulated onboard images. Experimental OBI was performed at 225 kVp, gain∕offset and scatter-glare were corrected. Simulated and experimentally obtained onboard images of phantoms and a mouse specimen were compared for a range of photon beam sizes from 2.5 cm down to 0.1 cm.


Simulated OBI can be used in small animal radiotherapy to determine if a treatment plan was delivered according to the prescription within an uncertainty of 5% for beams as small as 4 mm in diameter. For collimated beams smaller than 4 mm, beam profile differences remain primarily in the penumbra region of the smallest beams, which may be tolerable for specific preclinical micro-IR investigations.


Comparing simulated to acquired OBI during small animal treatment radiotherapy represents a useful treatment delivery tool.

[Indexed for MEDLINE]

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