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Biomedical subjects

M Ciocca

Publications and source records attributed to M Ciocca.

11 recordsLinked to original sources
PubMed1992

Beam modifying devices in the treatment of early breast cancer: 3-D stepped compensating technique.

A 3-D compensating technique utilizing stepped brass filters to ensure an adequate dose distribution in the breast after conservative surgery is described. No compensation for lung inhomogeneity is applied. These compensators are part of a procedure which also involves the use of a rotatable half-beam block (HBB) and of an individualized immobilization cast. Results of patient dosimetry show a good agreement with dose prescription in the target volume (measured dose/prescribed dose = 100.9% +/- 1.8% at the reference point). Phantom dosimetry is discussed.

Breast Neoplasms↗
PubMed1992

[Comparison of acceptance tests of 5 linear electron accelerators for radiotherapy].

The acceptance tests of five electron linear accelerators have been analyzed to compare their completeness, the standards specified by the manufacturers and the measured deviations. Involved tests were relative to geometrical and mechanical parameters, photon and electron beam characteristics, dose monitoring systems, treatment table and safety systems. The comparison of acceptance tests has shown a significant nonuniformity, also due to the absence of a specific legislation; anyway, the measured deviations generally appeared to be within internationally recommended values.

Particle Accelerators↗
PubMed1991

Quality control in the conservative treatment of breast cancer: patient dosimetry using silicon detectors.

Twenty patients with early breast cancer were treated with external irradiation, delivered with two tangential beams (6 MV X-rays) using a half-beam block (HBB) and 3-D compensating filters. All patients were immobilized with individualized cellulose acetate casts. Patient dosimetry was performed using p-type silicon detectors. Midline doses were calculated by combined entrance and exit dose measurements. The mean ratio of the measured and the prescribed doses was 96.6 +/- 3.8% at the reference point, 96.8 +/- 4.3% at off-axis points on the central plane and 96.8 +/- 7.6% at off-plane points.

Breast Neoplasms↗
PubMed1990

[Personalized low-melting alloy shield for high-energy electrons in the treatment of superficial neoplasms of critical or esthetically important regions].

Individualized Cerrobend beam shapings for high-energy electrons have been utilized in the treatment of superficial tumours located in aesthetic or critical regions. Individualized cellulose acetate masks have been used as immobilization device. Measured transmissions through Cerrobend ranged from 0.5% at 4 MeV to 8.5% at 18 MeV. Phantom dosimetry showed a poor influence of Cerrobend on PDD (percentage depth doses). Output factor variations appeared to depend on electron energy and shielded area. It is very important to perform either empirical measurements or to adopt semiempirical models in order to exactly calculate those output factors. Three clinical examples are presented: the utilization of immobilization device and field shaping are illustrated with the main aim of sparing the dose to critical organs.

Electrons↗
PubMed1990

[Verification of 3 computerized systems for drafting a plan for treatment with electrons].

The electron beam treatment planning systems, with the availability of more and more developed hardware for complex calculation algorithms, need quality controls of accuracy and comparability of treatment plans from different systems. In this paper three systems have been evaluated; their similar computation algorithms (pencil beam) have been used but in some conditions (beam reconstruction, oblique incidence and dishomogeneity) different results have been drawn. The basic data (PDD, dose profile, etc.) were the same for every system, therefore it has been observed that different results are mainly due to differences in: a) input of parameter values, b) calculation algorithm approximations, c) image acquisitions and elaboration.

Electrons↗
PubMed1989

[Treatment technic and clinical dosimetry in whole-body irradiation].

At the Istituto Nazionale Tumori, Milan, total-body irradiation (TBI) is delivered by a 15 MV linear accelerator, with two lateral opposed beams. Maximum build-up at the skin is achieved by lateral slabs of perspex 3 cm thick. Attenuation filters or bolus are used for dose compensation, or reduction, to the head and lungs. The dose delivered to clinically relevant anatomic regions is determined by "in vivo" dosimetry. For this purpose, calibrated diodes are employed, which are positioned at the entrance and at the exit of the beams. "In vivo" dosimetry data show our TBI technique to allow an homogeneous irradiation of all body areas, with maximum deviation of the mean dose value from reference point dose of -11% in the posterior abdomen, at the spinal cord shielded by arms.

Humans↗
PubMed1979

[Rectal tonometry in the differential diagnosis of constipation in pediatrics].

Based on the difficulties regarding the clinical, radiological, and histological diagnosis of colonic aganglionosis, we resorted the motility studies. Sixty-two children (15 days-10 years of age) were studied by means of rectal motility without knowing the results of the other auxilary methods. We obtained a clear difference between aganglionic and other group formed by constipated functional or psicogenic. We conclude that rectal motility studies have the advantage of being rapid and non-aggressive, besides avoiding rectal biopsy.

Child↗