[Dosimetry of electron beams: verification of the accuracy of an automatic dosimeter and a system for treatment planning]. / Dosimetria dei fasci di elettroni: verifica dell'accuratezza di un dosimetro automatico e di un sistema per piani di trattamento.

This study is part of a quality assurance programme evaluating the performances of two connected on-line systems (automatic dosimeter and treatment planning) and verifying the correctness of the applied algorithms and the accuracy of the basic beam data. We compared PDD measured in an automatic water phantom using a p-Si detector with point doses using an ion-chamber, for electron beams from a linac. To record dose distributions of scanned electron beams, the detector measurement time was triggered by the frame scan frequency. Data were automatically transferred to the treatment planning system by an interface. Measured and calculated isodose charts were compared for perpendicular incidence fields. Relative dose values calculated, in axis and off-axis points, were compared with those determined by the ion-chamber in the following situations: perpendicular and oblique incidence, different SSD.

[Radiotherapy of the breast after conservative surgery for primary carcinoma. Irradiation technic with matched fields]. / La radioterapia della mammella dopo chirurgia conservativa per carcinoma iniziale. Tecnica di irradiazione con fasci collimati.

The authors report their technique for breast radiotherapy following conservative surgery (quadrantectomy + axillary dissection). The breast and chest wall are irradiated with photons from a 60Co unit through two fixed opposing tangential fields. The posterior field edges must be parallel and coplanar to the chest wall. A routine treatment plan using simulator, pantograph and computerized console is standardized by mathematical formulae elaborated from geometric breast measurement parameters. Gammagraphies acquired prior to and during therapy allow verification and control of treatment parameters. For 35 patients the therapy plan as described was compared with that obtained by CT images. Our procedure proved valid and an accurate treatment plan could be elaborated even without CT images. The use of wedges, half-field blocks and the dose scattered to the contralateral breast are also discussed.

Radon and radon daughter evaluation in a natural radioactivity survey indoors.

An indoor survey in order to estimate the population exposure in five towns of an Italian Region is presented. A particular methodology for the campaign was planned and is being applied. Gamma spectrometry of building materials, exposure rate measurements indoors and outdoors and radon concentration measurements indoors were taken with different techniques. A correlation was found between mean gamma exposure rate and mean radon concentration in the houses investigated. An evaluation of mean effective dose equivalents for the inhabitants of the five towns is reported.