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Papers by Milena Frigerio

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...

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.

Radiotherapy and Oncology, 1998

With the improvements in treatment accuracy the risk exists of over-reliance on the capability of... more With the improvements in treatment accuracy the risk exists of over-reliance on the capability of the physician to estimate the extent of the tumour. We assessed the variability between six radiotherapists in defining the planning target volume (PTV) on CT slices for three prostate tumour cases. Percentage differences between measured volumes and mean values calculated for each case ranged from −53.64 to +60.48% (SD 36.00%). There is a considerable variation in delineating the PTV, both in the cranio-caudal direction and in the in-slice extension of the areas drawn on each slice (standard deviations ranged from 0.35 to 2.64 cm 2 ). We also checked the uncertainty in the shape and position of the contours on each CT image. The analysis was performed on three slices of one test case. As we expected, the uncertainty seems largest for seminal vesicle slices and smallest for prostatic apex slices. These results endorse the need for uncertainty analysis of all departmental processes in order to define a detailed protocol and consequently to minimize the interphysician differences in PTV delineations.

Radiation Oncology Investigations, 1998

Acute pneumonitis following breast irradiation is a rare and transient phenomenon that can be eas... more Acute pneumonitis following breast irradiation is a rare and transient phenomenon that can be easily managed by drugs. The aim of this study is to evaluate late sequelae on lung, after postoperative radiotherapy (RT) for breast cancer. We were concerned with investigating late radiological findings when very small lung volumes are involved in the irradiated volume. We studied 28 consecutive patients. They underwent clinical examination and all staging procedures before surgery, evaluation of pulmonary function with spirometry, postoperative chest x-ray and high resolution computed tomography (HRCT) of the lung before RT. Clinical examinations were usually performed every 3 months after RT. A second chest x-ray, HRCT and spirometry were carried out after nearly 7 months from the end of RT. We estimated the irradiated lung volume by measuring the area of the lung surface enclosed by the 50% isodose (LA50) in each profile. We found a significant correlation between LA50 and the score of radiological findings after RT. No correlations were found between other factors (i.e., adjuvant chemotherapy, age, weight, smoking) and lung fibrosis. No woman developed radiation pneumonitis syndrome or respiratory symptoms. Our results indicate that irradiation of the breast and/or chest wall is well tolerated if treatment planning is done accurately. The fibrosis likelihood is strongly correlated to the irradiated lung volume. The use of tangential fields limits radiological changes that can be detected only by HRCT examination and are not associated with clinical symptoms.

Medical Dosimetry, 2003

X-ray and light field alignment evaluation is carried out during linac quality assurance programs... more X-ray and light field alignment evaluation is carried out during linac quality assurance programs. In this paper, we compare the size of the light field measured by a photodiode and by a more traditional visual observation with the size of the x-ray field. The comparison between actual light field size, measured with the photodiode, and light field size measured by human eye allow us to verify the reliability of human eye in the evaluation of this parameter. The visual field is always larger than real light field; however, it agrees better with the x-ray field. It matches the light field if we take into account the 25% (؎ 1%) of the decrement line of the maximum central lightening; however, this method simulates better the actual field employed in radiation treatments.

Strahlentherapie und Onkologie, 1999

Purpose: The aim of this paper is to compare the EC-L Kodak system for radiation therapy beam loc... more Purpose: The aim of this paper is to compare the EC-L Kodak system for radiation therapy beam localization with a conventional one that could be daily employed in a Radiotherapy Department.

347Absolute dose outside planning target volume (PTV) in portal film verification

Radiotherapy and Oncology, 1996

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.

Radiotherapy and Oncology, 2011

The aim of this prospective single institution study is to get more knowledge of how to adapt com... more The aim of this prospective single institution study is to get more knowledge of how to adapt communication with patients during the period of radical first-line radiotherapy Materials: The study includes 30 patients with newly diagnosed head and neck cancer. The protocol consists of clinical examination, assessment of the patients'general condition, a questionnaire (EORTC QLQ with H&N module) and an interview at 0, 20, 40 and 60 Gy. The validated EORTC questionnaire was filled in at 0 and 60 Gy. Eight of the patients were depth interviewed. The protocol was approved by the local ethics committee. Results: Thirty of 37 patients who were asked for participation gave their informed consent and responded. The results show that 40% have been informed about skincare at 60 Gy. Forty-seven percent are informed about nutrition, and 23% about food and beverages that should be avoided during the treatment period. At the end of treatment 37% had a gastrostomy tube. Of all patients, 87% used analgesic medication at 60Gy. The average weight loss during six weeks was four kilos. Conclusions: The study shows that there is a great need for more information and supportive measures regarding nutrition and skin care.