Correction to BrainSCAN central axis dose calculations for 6-MV photon beams to lung with lateral electron disequilibrium

• Published in: International journal of radiation oncology, biology, physics Vol. 66; no. 4; pp. S102 - S107
• Main Authors: Geyer, Peter, Blank, Hilbert, Zips, Daniel, Alheit, Horst
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.11.2006
• Subjects: CHEST; CORRECTIONS; ELECTRON BEAMS; Lateral electron disequilibrium; Lung dose correction; LUNGS; PHANTOMS; PHOTON BEAMS; PLANNING; Primary dose; RADIATION DOSES; RADIOLOGY AND NUCLEAR MEDICINE; Primary dose; Lung dose correction; Photon beams; Lateral electron disequilibrium
• ISSN: 0360-3016; 1879-355X
• DOI: 10.1016/j.ijrobp.2006.03.067

Purpose: To develop and evaluate a correction method for lateral electron disequilibrium and tissue inhomogeneities in lung tissues applicable to the BrainSCAN treatment planning system. Methods and Materials: Four noncoplanar 6-MV photon beams with different beam diameters were applied to the right lung of a thorax phantom. The measured/calculated dose value ratio was evaluated as a function of a parameter that describes the degree of the lateral electron disequilibrium based on the primary dose. Results: The dose ratio showed a clearcut linear dependency on the disequilibrium parameter. Applying the proposed correction method, only minor differences between the measured and calculated doses were found for lesions >1 cm. However, for lesions <1 cm surrounded by lung tissue the difference was ≤15%. Conclusion: The data have indicated a relevant magnitude of the correction factor only for lung lesions <1 cm.