Study of lung density corrections in a clinical trial (RTOG 88-08)

Determination of CT-to-density conversion relationship for image-based treatment planning systems

“…[1][2][3][4][5][6][7] Patient data are now acquired within a short time using the new generation fast helical computed tomography (CT) scanners. The CT images are then downloaded into a treatment planning system.…”

Predicting Changes in Dose Distribution to Tumor and Normal Tissue When Correcting for Heterogeneity in Radiotherapy for Lung Cancer

“…1,2,8,11 These regions include lung-tumor interfaces and the field edges within the lung tissue. The electronic disequilibrium effect becomes more significant with high-energy photon beams.…”

“…1 Many institutions are adopting heterogeneity correction for thoracic targets to calculate precise dose distribution data to tumor and normal tissues. In many sites outside the thorax, variations in tissue densities are not significant, but in the thorax, lung tissue typically has a physical density of approximately 30% that of soft tissue.…”

Monte Carlo dose calculations for a 6-MV photon beam in a thorax phantom

“…Also, the dose in the lung will be wrongly predicted especially in small fields and at greater depths, thus hampering dose optimization based on dose levels in organs at risk. [1][2][3] …”

“…Therefore, if the tissue inhomogeneity effect is not accurately predicted during dose calculations, unacceptable errors may arise and cause underdosage of tumors or overdosage of healthy surrounding tissues. [1][2][3] Recently, new techniques for treating cancers such as three-dimensional conformal radiotherapy and intensity-modulated radiation therapy (IMRT) have been developed, and the application of these techniques to small fields and high-energy photons in the thoracic region have been studied by several investigators. 4 In addition, stereotactic irradiation (STI) of lung cancer using a linear accelerator has been implemented in some centers.…”