Radiation doses to normal tissues and organs outside the target volume during radiotherapy

Public Health Codes more and more require that any information relevant to the estimation of the high doses delivered within the target volumes and low doses delivered outside should be recorded. In this context, the availability for each radiotherapy patient of the magnitude of the unavoidable low doses delivered outside the target-volumes becomes an important issue. However, to date, Treatment Planning Systems (TPS) are not designed for this issue. Therefore, we have developed a new version of the ISOgray TPS which can provide, in addition to the doses distributions in the fields, the magnitude of the doses to distant healthy tissues in the course of common radiotherapeutic procedures. Our strategy involves 3 modules: A library of adjustable whole-body patient models in treatment position which allows different patient anatomies to be simulated; A multi-sources beam model, which allows the description of the irradiation field to be extended to the whole body; A dose calculation engine producing the distributions of doses in the fields and in any organ outside. This paper describes the principles of the system and provides data on doses distributions to distant organs for various common radiotherapeutic procedures. At this stage of development, the agreement of measured and calculated doses reaches ±3% in the radiation field and is better than ±15% outside. In the case of a 17 years aged girl treated for Hodgkin's disease using two 6MV opposite photon beams, when a dose of 20 Gy was delivered to the target volume, outside the beam, the dose to the brain was 0.37 Gy (1.85% of the tumor dose), the kidney 0.06 Gy (0.30%) and the ovaries below 0.02 Gy (<0.1%). Although the development of our system is still in progress, these preliminary results are encouraging. Allowing the realization of whole-body dose evaluations for each patient in the course of radiation therapy treatment planning, our approach must provide relevant information required to meet the current requirements of patient radiation protection and radiation therapy benefit-risk management purposes. The systematic evaluation of low doses outside the radiation therapy fields creates new opportunities in quality assurance of radiation therapy and prospective studies of long-term risks of radiation modern radiotherapeutic procedures

Genetic Diversity and Demographic History of Wild and Cultivated/Naturalised Plant Populations: Evidence from Dalmatian Sage (Salvia officinalis L., Lamiaceae)

Dalmatian sage (Salvia officinalis L., Lamiaceae) is a well-known aromatic and medicinal Mediterranean plant that is native in coastal regions of the western Balkan and southern Apennine Peninsulas and is commonly cultivated worldwide. It is widely used in the food, pharmaceutical and cosmetic industries. Knowledge of its genetic diversity and spatiotemporal patterns is important for plant breeding programmes and conservation. We used eight microsatellite markers to investigate evolutionary history of indigenous populations as well as genetic diversity and structure within and among indigenous and cultivated/naturalised populations distributed across the Balkan Peninsula. The results showed a clear separation between the indigenous and cultivated/naturalised groups, with the cultivated material originating from one restricted geographical area. Most of the genetic diversity in both groups was attributable to differences among individuals within populations, although spatial genetic analysis of indigenous populations indicated the existence of isolation by distance. Geographical structuring of indigenous populations was found using clustering analysis, with three sub-clusters of indigenous populations. The highest level of gene diversity and the greatest number of private alleles were found in the central part of the eastern Adriatic coast, while decreases in gene diversity and number of private alleles were evident towards the northwestern Adriatic coast and southern and eastern regions of the Balkan Peninsula. The results of Ecological Niche Modelling during Last Glacial Maximum and Approximate Bayesian Computation suggested two plausible evolutionary trajectories: 1) the species survived in the glacial refugium in southern Adriatic coastal region with subsequent colonization events towards northern, eastern and southern Balkan Peninsula; 2) species survived in several refugia exhibiting concurrent divergence into three genetic groups. The insight into genetic diversity and structure also provide the baseline data for conservation of S. officinalis genetic resources valuable for future breeding programmes