Equivalent uniform dose concept evaluated by theoretical dose volume histograms for thoracic irradiation.

BACKGROUND AND PURPOSE: The goal of our study was to quantify the limits of the EUD models for use in score functions in inverse planning software, and for clinical application. MATERIALS AND METHODS: We focused on oesophagus cancer irradiation. Our evaluation was based on theoretical dose volume histograms (DVH), and we analyzed them using volumetric and linear quadratic EUD models, average and maximum dose concepts, the linear quadratic model and the differential area between each DVH. RESULTS: We evaluated our models using theoretical and more complex DVHs for the above regions of interest. We studied three types of DVH for the target volume: the first followed the ICRU dose homogeneity recommendations; the second was built out of the first requirements and the same average dose was built in for all cases; the third was truncated by a small dose hole. We also built theoretical DVHs for the organs at risk, in order to evaluate the limits of, and the ways to use both EUD(1) and EUD/LQ models, comparing them to the traditional ways of scoring a treatment plan. For each volume of interest we built theoretical treatment plans with differences in the fractionation. CONCLUSION: We concluded that both volumetric and linear quadratic EUDs should be used. Volumetric EUD(1) takes into account neither hot-cold spot compensation nor the differences in fractionation, but it is more sensitive to the increase of the irradiated volume. With linear quadratic EUD/LQ, a volumetric analysis of fractionation variation effort can be performed.

[Rectal complications of radiotherapy]. / Les complications rectales de la radiothérapie.

Late rectal morbidity has been observed in 2%-25% of patients treated with radiotherapy using curative doses for prostate, cervix and rectal cancers. The major encountered clinical pictures are rectal proctitis, rectal/anal strictures, rectal bleeding, ulcers and fistula. Some may alter the patient's lifestyle while other may induce death. Recommendations concerning the clinical practice are described. The treatment of these late rectal effects include nutritional recommendations, laser, formalin application, and surgery.

[Irradiation in radiodiagnosis: recent possibilities of decreasing the doses (author's transl)]. / L'irradiation en radiodiagnostic: possibilités récentes de diminution des doses

Depending on the film used, the new super-fast re-enforcing screens enable a four to six fold reduction in diagnosis cutaneous irradiation. This diagnosis irradiation which remains rather considerable under classical techniques, is frequently injustly neglected: the distribution of this new type of material seems desireable. On the contrary, the use of xeroradiography leads to an irradiation which is three times greater than in conventional techniques and fifteen times greater than in these new techniques: xeroradiography must therefore be reserved for very specific problems.