Implications of lung corrections for dose specification in radiotherapy

Area of Science:

• Radiation Oncology
• Medical Physics
• Radiotherapy

Background:

• Accurate dose calculation is critical in lung cancer radiotherapy.
• Lung tissue's low density can significantly alter radiation dose distribution.
• Current treatment planning often overlooks lung density corrections.

Purpose of the Study:

• To evaluate the impact of incorporating lung density into dose calculations for bronchus carcinoma patients.
• To quantify the dose variations resulting from lung correction.
• To assess the effect of lung correction on target dose homogeneity and normal tissue sparing.

Main Methods:

• Utilized CT scans for anatomical and electron density data from 23 lung cancer patients.
• Performed dose distribution calculations for cobalt-60 gamma rays using patient-specific multiple field irradiation.
• Applied a generalized Batho's method to account for lung tissue effects on dose.

Main Results:

• Corrected minimum tumor doses ranged from 63 Gy to 77 Gy (105-128%) compared to uncorrected plans.
• Lung density correction altered dose homogeneity within the target area.
• Dose to surrounding normal tissues was also affected by the lung correction.

Conclusions:

• Lung density correction is essential for precise radiotherapy dose planning in lung cancer.
• The study highlights significant underestimation of tumor dose when lung density is ignored.
• Findings necessitate re-evaluation of standard dose prescription protocols in lung cancer treatment.