Milena Frigerio | Università degli Studi dell'Insubria (original) (raw)

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Papers by Milena Frigerio

Research paper thumbnail of Postoperative adjuvant radio(chemo)therapy for rectal cancer: an appraisal

Tumori

Rectal cancer can be considered a broad-spectrum disease, where the surgeon, radiation oncologist... more Rectal cancer can be considered a broad-spectrum disease, where the surgeon, radiation oncologist and medical oncologist have a peculiar and specific place in order to work harmoniously as a good orchestra. The reality in common general hospitals is far from that of comprehensive cancer centers, particularly for postoperative approaches. The adjuvant therapy of rectal cancer is not codified worldwide, and it is strongly dependent on preoperative staging procedures, surgeon's acts and pathologist's decisions. Starting from our 10-year experience, we analyzed the various steps of postoperative approaches, defining possible decision errors, the incongruity of some attitudes, and the lack of knowledge of recent achievements of science in this disease. A total of 194 patients with advanced surgically removed rectal cancer (pT3-4 pN0-any pT pN+) treated with postoperative radio(chemo)therapy was reviewed retrospectively. Anterior resection was performed in 126, abdominoperineal re...

Research paper thumbnail of The Effects of Focus-Skin Distance and Shaping Block Tray on the Calibration Factor of In-Vivo Dosimetry Diodes

Strahlentherapie und Onkologie, 2000

In-vivo dose measurements during conformal treatment require correction factor evaluations for di... more In-vivo dose measurements during conformal treatment require correction factor evaluations for differences in block shapes, field size and source-skin distance (SSD). The aim of this paper is to evaluate a single correction factor, CFentranceSSD, depending only on source-skin distance, which takes into account both shape and size of blocked fields, in pelvic treatments. A set of measurements was performed to investigate the effects of different block shapes and sizes, source-skin distances and collimator settings on the entrance dose values. For this reason EDP 20 Scanditronix diodes, with 20 mm water-equivalent build-up cap, were irradiated by 2 Varian linear accelerators (Clinac 1800 and Clinac 2100) 18 MV photon beams with 3 different collimator settings. Diodes were calibrated by comparison with a Farmer 2571 ionization chamber at reference conditions (10 cm x 10 cm open field, source-skin distance 100 cm, build-up depth 3.3 cm) in order to convert the semiconductor signal into water absorbed dose. Three sets of different measurements (regarding open beams, tray fields and shaped fields) were performed. Diode responses were compared with the ionization chamber ones, in the same irradiation conditions. The CFentranceSSD trends can be described by linear fits in dependence upon source-skin distance, and the effect with tray alone or with tray and blocks is stronger than in the open field. The observed effects can be interpreted by the influences of a) the different source distances of diode and reference point in the phantom and b) the secondary electron contamination of the photon beam upon the calibration factor of the diode. The effects of source-skin distance and of the shaping blocks and tray upon the diode calibration factor can be effectively accounted for by a single CFentranceSSD correction factor.

Research paper thumbnail of Interphysician variability in defining the planning target volume in the irradiation of prostate and seminal vesicles

Radiotherapy and Oncology, 1998

Research paper thumbnail of Radiological findings when very small lung volumes are irradiated in breast and chest wall treatment

Radiation Oncology Investigations, 1998

Research paper thumbnail of Visual verification of linac light and radiation fields coincidence

Research paper thumbnail of Contrast improvement in a new radiotherapy imaging system

Strahlentherapie und Onkologie, 1999

Research paper thumbnail of 347Absolute dose outside planning target volume (PTV) in portal film verification

Radiotherapy and Oncology, 1996

Research paper thumbnail of An equivalent square method for irregular photon fields

Medical Dosimetry, 1995

A quick formula is proposed for calculating equivalent squares of irregularly shaped photon field... more A quick formula is proposed for calculating equivalent squares of irregularly shaped photon fields. No complex calculations are required. Three different energies (60Co; 6 MV and 18 MV x-rays) were investigated. Comparison with results utilizing the Clarkson technique (60Co) and with experimental measurements (6 MV and 18 MV x-rays) indicates that the method is accettable in a wide variety of clinical situations. The applied procedure introduces an indetermination lower than 4%, with maximum absolute percentage errors of 3%, 2.7%, and 3.6% for 6 MV, 18 MV, and 60Co photon fields respectively.

Research paper thumbnail of 1409 poster TOWARDS A HOSPITAL-BASED BNCT WITH A STANDARD RADIO-THERAPIC LINAC

Radiotherapy and Oncology, 2011

Research paper thumbnail of Postoperative adjuvant radio(chemo)therapy for rectal cancer: an appraisal

Tumori

Rectal cancer can be considered a broad-spectrum disease, where the surgeon, radiation oncologist... more Rectal cancer can be considered a broad-spectrum disease, where the surgeon, radiation oncologist and medical oncologist have a peculiar and specific place in order to work harmoniously as a good orchestra. The reality in common general hospitals is far from that of comprehensive cancer centers, particularly for postoperative approaches. The adjuvant therapy of rectal cancer is not codified worldwide, and it is strongly dependent on preoperative staging procedures, surgeon's acts and pathologist's decisions. Starting from our 10-year experience, we analyzed the various steps of postoperative approaches, defining possible decision errors, the incongruity of some attitudes, and the lack of knowledge of recent achievements of science in this disease. A total of 194 patients with advanced surgically removed rectal cancer (pT3-4 pN0-any pT pN+) treated with postoperative radio(chemo)therapy was reviewed retrospectively. Anterior resection was performed in 126, abdominoperineal re...

Research paper thumbnail of The Effects of Focus-Skin Distance and Shaping Block Tray on the Calibration Factor of In-Vivo Dosimetry Diodes

Strahlentherapie und Onkologie, 2000

In-vivo dose measurements during conformal treatment require correction factor evaluations for di... more In-vivo dose measurements during conformal treatment require correction factor evaluations for differences in block shapes, field size and source-skin distance (SSD). The aim of this paper is to evaluate a single correction factor, CFentranceSSD, depending only on source-skin distance, which takes into account both shape and size of blocked fields, in pelvic treatments. A set of measurements was performed to investigate the effects of different block shapes and sizes, source-skin distances and collimator settings on the entrance dose values. For this reason EDP 20 Scanditronix diodes, with 20 mm water-equivalent build-up cap, were irradiated by 2 Varian linear accelerators (Clinac 1800 and Clinac 2100) 18 MV photon beams with 3 different collimator settings. Diodes were calibrated by comparison with a Farmer 2571 ionization chamber at reference conditions (10 cm x 10 cm open field, source-skin distance 100 cm, build-up depth 3.3 cm) in order to convert the semiconductor signal into water absorbed dose. Three sets of different measurements (regarding open beams, tray fields and shaped fields) were performed. Diode responses were compared with the ionization chamber ones, in the same irradiation conditions. The CFentranceSSD trends can be described by linear fits in dependence upon source-skin distance, and the effect with tray alone or with tray and blocks is stronger than in the open field. The observed effects can be interpreted by the influences of a) the different source distances of diode and reference point in the phantom and b) the secondary electron contamination of the photon beam upon the calibration factor of the diode. The effects of source-skin distance and of the shaping blocks and tray upon the diode calibration factor can be effectively accounted for by a single CFentranceSSD correction factor.

Research paper thumbnail of Interphysician variability in defining the planning target volume in the irradiation of prostate and seminal vesicles

Radiotherapy and Oncology, 1998

Research paper thumbnail of Radiological findings when very small lung volumes are irradiated in breast and chest wall treatment

Radiation Oncology Investigations, 1998

Research paper thumbnail of Visual verification of linac light and radiation fields coincidence

Research paper thumbnail of Contrast improvement in a new radiotherapy imaging system

Strahlentherapie und Onkologie, 1999

Research paper thumbnail of 347Absolute dose outside planning target volume (PTV) in portal film verification

Radiotherapy and Oncology, 1996

Research paper thumbnail of An equivalent square method for irregular photon fields

Medical Dosimetry, 1995

A quick formula is proposed for calculating equivalent squares of irregularly shaped photon field... more A quick formula is proposed for calculating equivalent squares of irregularly shaped photon fields. No complex calculations are required. Three different energies (60Co; 6 MV and 18 MV x-rays) were investigated. Comparison with results utilizing the Clarkson technique (60Co) and with experimental measurements (6 MV and 18 MV x-rays) indicates that the method is accettable in a wide variety of clinical situations. The applied procedure introduces an indetermination lower than 4%, with maximum absolute percentage errors of 3%, 2.7%, and 3.6% for 6 MV, 18 MV, and 60Co photon fields respectively.

Research paper thumbnail of 1409 poster TOWARDS A HOSPITAL-BASED BNCT WITH A STANDARD RADIO-THERAPIC LINAC

Radiotherapy and Oncology, 2011