Analysis of Clinical data
Salivary glands
Fig 1. Function loss for the parotid glands below and above specified dose thresholds (a) and calculated dose response curves for IMRT-treatments (b).
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For radiotherapy treatments of head-and-neck tumors, the salivary glands are often within the treatment fields and may receive high doses. Xerostomia may be the consequence, which severely affects life quality of patients. Using intensity-modulated radiotherapy (IMRT) the degree of dose conformation to the tumor can be improved and the dose to at least one parotid gland can be significantly reduced.
To assess the preservation of salivary gland function, functional parameters are measured using quantitative pertechnetate scintigraphy. The change of these parameters before and after radiotherapy are analyzed as a a function of dose and dose response relations are derived (fig. 1). In addition, the functional changes between different treatment modalities are compared. These treatment modalities include conventional radiotherapy with and without administration of the radio-protector Amifostine and IMRT.
Lung
Radiological changes in computed tomography (CT) after radiotherapy of lung tumors are regarded as a leading sign for radiological fibrosis, which subsequently may lead to clinical pneumonitis. In such cases, loss of lung function may be the consequence. To avoid such complication, the irradiated volume of the lung should be kept as small as possible. For selected lung tumors, the irradiated volume may be minimized by rigid immobilization of the patient and by applying a high single dose (stereotactic Radiosurgery).
For a collective of patient with lung tumors treated, the probability of radiological changes in CT after stereotactic radiosurgery is investigated and dose response curves are derived. In addition, the clinical response is analyzed as a function of the irradiated volume and the location of the tumor. Quantitative predictive parameters shell be derived to allow the estimation of complication probabilities in radiosurgery of the lung already at the stage of treatment planning.
Cooperations
- Dr. M. Münter, Dr. H. Hof, Dept. of Radiation Oncology and Radiotherapy, University Clinic Heidelberg, Germany
Selected References
- Münter M.W., Karger C.P., Hoffner S.G., Hof H., Thilmann C., Rudat V., Nill S., Wannenmacher M., Debus J.; Evaluation of salivary gland function after treatment of head-and-neck tumors with intensity-modulated radiotherapy by quantitative pertechnetate scintigraphy. International Journal of Radiation Oncology, Biology, Physics 58, 175-184, 2004
- Hof H., Herfarth K.K., Munter M., Hoess A., Motsch J., Wannenmacher M., Debus J.: Stereotactic single-dose radiotherapy of stage I non-small-cell lung cancer (NSCLC). Int. J. Radiat. Oncol. Biol. Phys. 56, 335-341, 2003