A quality assurance programme in brachytherapy implies a general consensus on the method of dose and volume specification for reporting. This in turn implies a consensus on certain definitions of terms and concepts. For several decades, the ICRU (International Commission on Radiation Units and Measurements) has been actively involved in an effort to reach a consensus between different brachytherapy centres worldwide, and to improve uniformity in reporting. The ICRU has prepared two reports containing recommendations for reporting brachytherapy treatments. The first, report #38 published in 1985, deals with intracavitary therapy in gynecology. The second deals with interstitial therapy, and is now in press. A summary of these two ICRU reports is presented here. Some definitions of terms and concepts are first recalled and discussed: Total Reference Air Kerma (TRAK), gross tumor volume (GTV), clinical target volume (CTV), treated volume, mean central dose, dose uniformity parameters, etc. Specific recommendations for reporting interstitial and intracavitary brachytherapy are then presented.

Brachytherapy↗

PubMedDate not supplied

[Response of digestive tract mucosa to single and fractionated irradiation. Practical implications for radiotherapy].

After a short description of the gastro-intestinal syndrome (for a single "acute" irradiation) and a discussion of the importance of fractionation in radiotherapy, the authors report their experimental results on intestinal tolerance in mice after fractionated irradiation. Intestinal tolerance was assessed from LD50 after abdomen irradiation. Variation of LD50 was first studied as a function of the fraction number N (keeping constant the overall time T). From these data iso-effect curves were calculated which can be used for clinical applications for correcting the total dose when the fraction number has to be modified (for T constant). In a second series of experiments, variation of LD50 was studied as a function of overall time T (keeping constant the fraction number N), this study confirms the large recovery capability of the intestinal mucosa, which is due to the combination of 2 mechanisms: shortening of the mitotic cycle of the surviving stem cells and increase of the size of the stem cell compartment. These 2 mechanisms were evaluated quantitatively for a fractionated irradiation. The data obtained for intestine are compared to similar data obtained for other tissues (skin, lung). The authors emphasize the risk of applying to late effects the conclusions obtained for early effets.

Animals↗