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Measuring Nucleotide Binding to Intact, Functional Membrane Proteins in Real Time

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Ion stopping powers and CT numbers.

Michael F Moyers¹, Milind Sardesai, Sean Sun

¹Department of Proton Therapy, Inc., Colton, CA 92324, USA. MFMoyers@roadrunner.com

Medical Dosimetry : Official Journal of the American Association of Medical Dosimetrists

|November 26, 2009

Summary

Accurate ion beam therapy requires precise stopping power data for all materials. This study measured relative linear stopping powers (RLSPs) and CT numbers for various materials to improve treatment planning accuracy.

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Area of Science:

Medical Physics
Radiation Oncology
Materials Science

Background:

Ion beam therapy offers precise dose delivery due to steep dose gradients.
Accurate dose calculations in treatment planning systems depend on accurate stopping power data for all beam path materials.
Standard conversion curves for kilovoltage CT numbers to stopping powers may not apply to all materials encountered in patient scans.

Purpose of the Study:

To measure the relative linear stopping powers (RLSPs) of various tissue substitute and phantom materials.
To determine the kilovoltage (kVCT) and megavoltage (MVCT) CT numbers for these materials.
To establish relationships between RLSPs, CT numbers, and other material properties for improved treatment planning.

Main Methods:

Measured RLSPs for 21 materials using proton, carbon ion, and iron ion beams at various energies.
Acquired kVCT and MVCT numbers for the same materials.
Compared measured RLSPs and CT numbers with calculated and literature values.

Main Results:

Provided measured RLSPs and CT numbers for 21 materials.
Established relationships between RLSPs and physical density, electronic density, kVCT number, MVCT number, and treatment planning system-derived water equivalence.
Demonstrated that some materials deviate from standard tissue conversion curves.

Conclusions:

Accurate RLSPs and CT numbers are crucial for precise ion beam therapy dose calculations.
The measured data and established relationships can enhance the accuracy of patient and phantom simulations in treatment planning.
This work provides valuable data for improving the accuracy of ion beam therapy planning.