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Measurement of lung density by computed tomography: implication for radiotherapy
The Keio Journal of Medicine
|December 1, 1989
Summary
Accurate lung density measurement using computed tomography (CT) is crucial for precise radiotherapy planning. Lung densitometry ensures correct radiation dosage, minimizing variations for effective cancer treatment.
Area of Science:
- Medical Physics
- Radiotherapy
- Diagnostic Imaging
Background:
- Accurate radiotherapy treatment planning requires precise knowledge of tissue density.
- Computed tomography (CT) densitometry offers a method for assessing lung density.
- Variations in lung density can impact radiation dose delivery.
Purpose of the Study:
- To evaluate the reliability of CT densitometry for lung density assessment.
- To determine lung density values in patients for radiotherapy planning.
- To establish acceptable CT value variations for accurate radiation dosing.
Main Methods:
- CT scans of cork phantoms were performed to test densitometry reliability.
- Lung densities were measured in 50 patients across different lung regions and breathing phases.
- CT values were corrected using the CT value of pure water.
Main Results:
- CT densitometry of cork phantoms showed acceptable errors for radiotherapy.
- Patient lung densities varied significantly between inspiration and expiration, and across lung regions.
- CT number variations exceeding 60 HU were observed between subjects and lung locations.
Conclusions:
- Lung densitometry is essential before lung radiotherapy to ensure accurate radiation dosage.
- CT densitometry provides reliable lung density data for treatment planning.
- Managing CT value variations is critical for maintaining dose consistency within 2%.