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S Broggi

Publications and source records attributed to S Broggi.

14 recordsLinked to original sources
PubMed2002

In vivo estimation of midline dose maps by transit dosimetry in head and neck radiotherapy.

The aim of the present study is to compare the calculated midline dose map with the in vivo measured midline dose map, using portal detectors in conjunction with a pair of diodes. Measurements were performed in 10 patients treated for head/neck cancer and irradiated with lateral opposed 6 MV X-ray beams. The relative exit dose map, derived from transmission dose data of a portal film combined with the absolute entrance/exit dose measured by the diodes, can be used to derive the corresponding midline dose map by applying appropriate algorithms. Midplane dose values were estimated in eight relevant anatomic positions and compared with the corresponding calculated values with our three-dimensional (3D) treatment planning system using two-dimensional (2D) (Batho) and 3D (ETAR) inhomogeneity correction algorithms. In vivo estimated midplane doses agree within +/-3.5% relative to treatment planning calculations in 89 of 116 measurements points, with only 4 of 116 points outside +/-5%. A variation between measured and calculated dose can be found according to anatomical location. For air inhomogeneity, mean deviations were +2.2% (1 standard deviation (SD) approximately 1.7%) for both Batho and ETAR algorithms; for bone structures, mean deviations were approximately -0.6% (1 SD approximately 2.7%) for both algorithms. The worst agreement was found in the anterior neck where the mean deviation between measured and calculated midline dose was +3.1% (1 SD=1.4%) and +3.4% (1 SD= 2%) using Batho and ETAR, respectively. Sufficiently accurate 2D midplane dose maps may be simply obtained in vivo in the irradiation of head/neck cancer by using a portal detector in combination with a pair of diodes, in order to verify the dose actually delivered during treatment.

Algorithms↗
PubMed2001

Non-motor effects of deep brain stimulation of the subthalamic nucleus in Parkinson's disease: preliminary physiological results.

Although deep brain stimulation (DBS) is a clinically effective therapy for patients with advanced Parkinson's disease (PD), its physiological effects on the brain and possible actions on non-motor functional systems remain largely unknown. This study evaluated the effects of DBS of the subthalamic nucleus (STN) on neurophysiological variables and on cardiovascular physiology. Nine patients affected by PD undergoing chronic DBS of the STN have been studied. We performed electroencephalography (EEG), somatosensory (SEPs) and visual evoked potentials (VEPs), exteroceptive masseteric silent period and sympathetic skin response (SSR) studies with DBS ON and OFF. To assess the effects of stimulation on the cardiovascular system the tilt test and plasma renin activity were studied. When we turned the DBS OFF, both SEP N20 and the VEP P100 component increased significantly in amplitude whereas the SSR decreased in amplitude and increased in latency. Although plasma renin activity tended to increase with DBS OFF, its modification induced by postural changes and blood pressure values did not significantly differ with DBS ON and OFF. We conclude that DBS of the STN in PD, besides inducing a clinical improvement, induces several non-motor effects.

Afferent Pathways↗
PubMed2001

A simple and robust method for in vivo midline dose map estimations using diodes and portal detectors.

INTRODUCTION: This work investigates the possibility of using a pair of diodes on the beam axis in conjunction with a portal imaging detector to estimate in vivo midline dose distributions, without any additional patient information, related to the external body contour. MATERIALS AND METHODS: In the proposed method, the patient is considered equivalent to a parallelepiped phantom with a thickness z equal to the patient's physical thickness on the field axis with a variable electronic density rho, depending on the water-equivalent thickness. Based on this assumption, if the air gap between portal detector and patient is kept small (within 10-15 cm), the relative exit dose map may be assumed to be equal to the corresponding map measured at the portal detector level by geometrical back projection to the corresponding exit points. The relative exit dose map is then normalized at the on-axis value measured by the exit diode. The entrance dose map is derived by correcting the absolute dose value measured with the diode at the entrance surface by the off-axis ratios. For each pair of entrance and exit doses, the midline dose may be estimated by applying algorithms reported in literature. The method was tested in 6 MV beams using portal film as detector and the Huyskens and Rizzotti algorithms for midline dose estimation. Tests on homogeneous cubic phantoms, homogeneous phantoms with varying thickness symmetrically (simulating head and neck regions) and asymmetrically (simulating abdomen/pelvis region), and a half-sphere phantom with simulating the breast, were performed. Midline doses estimated with the proposed method have been compared with corresponding ones measured by ionisation chamber. RESULTS AND DISCUSSION: Results confirm that the proposed method can be used to estimate midplane dose maps within 2-3% for most clinically suitable situations. For homogeneous symmetrical phantoms the agreement between estimated and measured midline doses decreases with the phantom-portal film distance, the field sizes and the thickness. For homogeneous asymmetrical phantoms the percentage deviations are generally within 3%. Discrepancies larger than 3% (up to 5-6%) are found only for "stressed" irradiation geometries which are not linked with any clinical condition. CONCLUSIONS: The obtained results not only show the accuracy of the proposed method but, due to its simplicity, suggest a rapid clinical implementation of this method in relevant clinical situations such as head-neck, breast and abdomen/pelvis irradiation. Previous investigations which confirmed the possibility of using portal detectors for transit dosimetry in inhomogeneous regions suggest the further exploration of the accuracy and the limits of the proposed method in such cases.

Abdomen↗
PubMed2000

Conformal irradiation of concave-shaped PTVs in the treatment of prostate cancer by simple 1D intensity-modulated beams.

BACKGROUND: In the case of concave-shaped PTVs including prostate (P) and seminal vesicles (SV), intensity-modulated radiation therapy (IMRT) should improve the therapeutic ratio of the treatment of prostate cancer. PURPOSE: Comparing IMRT by simple 1D modulations with conventional 3D conformal therapy (i.e. non-IMRT) in the treatment of concave-shaped PTVs including P+SV. MATERIALS AND METHODS: For five patients having a concave-shaped PTV (P+SV) previously treated at our Institute with conformal radiotherapy, conventional 3- and 4-fields conformal plans were compared with IMRT plans in terms of biological indices. IMRT plans were generated by using five equi-spaced beams with a partial shielding of the rectum obtainable with our single-absorber modulation technique (Fiorino C, Lev A, Fusca M, Cattaneo GM, Rudello F, Calandrino R. Dynamic beam modulation by using a single dynamic absorber. Phys. Med. Biol. 1995;40:221-240). The modulation was one-dimensional and the shape of the beams was at single minimum in correspondence with the 'core' of the rectum; the beam intensity in the minimum was set equal to 20 or 40% of the open beam intensity. All plans were simulated on the CADPLAN TPS using a pencil-beam based algorithm (with 18 MV X-rays). Tumour control probability (TCP) and normal tissue complication probabilities (NTCPs) (for rectum, bladder and femoral head) were calculated for all situations when varying the isocentre dose from 60 to 90 Gy. Dose distributions were corrected taking dose fractionation into account through the linear-quadratic model; for the TCP/NTCP estimations the Webb-Nahum and the Lyman-Kutcher models were respectively applied. Three different scores were considered: (a) increase of TCP while keeping rectum NTCP equal to 5% (TCP(5%)); (b) increase of the uncomplicated tumour control probability (P+); (c) increase of the biological-based scoring function (S+), developed by Mohan et al. (Mohan R, Mageras GS, Baldwin B, Clinically relevant optimization of 3D conformal treatments. Med. Phys. 1992;19:933-944). The impact of the uncertainty in the knowledge of the parameters of the biological models was investigated for TCP(5%). RESULTS: (a) The average gain in TCP(5%) when considering IMRT against non-IMRT conformal plans was 7.3% (range 5.0-13.5%); (b) the average increase of P+ was 3.4% (range: 1. 0-8.5%); and (c) the average increase of S+ was 5.4% (range 2.9-12. 4%). The largest gain was found for one patient (patient 5) showing a significantly larger overlapping between PTV and rectum. CONCLUSIONS: Simple 1D-IMRT may clearly improve the therapeutic ratio in the treatment of concave-shaped PTVs including P and SV. In the range of clinically suitable values, the impact of the uncertainty of the parameters n and sigma(alpha) does not significantly alter the main results concerning the gain in TCP(5%). The reported gain in terms of P+ and S+ should be considered with great caution because of the intrinsic uncertainties of the model's parameters and, for bladder, because the 'true' DVH (considering variations of the shape and dimension due to variable filling) may be very different from the DVH calculated on a single CT scan. Further investigations should consider inversely-optimised 1D and 2D-IMRT plan in order to compare them in terms of cost-benefit.

Algorithms↗
PubMed2000

Quality assurance by systematic in vivo dosimetry: results on a large cohort of patients.

BACKGROUND: In vivo dosimetry is widely considered to be an important tool for quality assurance in external radiotherapy. INTRODUCTION: In this study we report on our experience over more than 4 years in systematic in vivo dosimetry with diodes. MATERIALS AND METHODS: From November '94 an in vivo entrance dosimetry check was performed for every new patient irradiated at one of our treatment units (Linac 6/100, 6 MV X-rays). Diodes were calibrated in terms of entrance dose; appropriate correction factors had been previously assessed (taking SSDs, field width, wedge, oblique incidence and blocking tray into account) and were individually applied to in vivo diode readings. The in vivo measured entrance dose was compared with the expected one, with a 5% action level; if a larger deviation was found, all treatment parameters were verified, and the in vivo dosimetry check was repeated. During the period November '94-May '99, 2824 measurements on 1433 patients were collected. RESULTS: Nine out of 1433 (0.63%) serious systematic errors (leading to a 5% or more on the delivered dose to the PTV) were detected by in vivo dosimetry; four out of nine would produce a 10% or more error if not detected. The rate of serious systematic errors detected by an independent check of treatment chart and MU calculation was found to be 1.5%, showing that less than 1/3 of the errors escapes this check. One hundred and twelve out of 1433 (7.8%) patients had more than one check: the rate of second checks was significantly higher for breast patients (31/250, 12.4%) against non-breast patients (81/1183, 6.8%, P=0.003). A number of patients demonstrated a persistent relatively large error even after two or more checks. For almost all patients the cause of the deviation was assessed; the most frequent cause was the difficulty in correctly positioning the patient and/or the diode. When analyzing the distribution of the deviations between measured and expected entrance doses (excluding first checks in the case of repetition of the in vivo dosimetry control) the mean deviation was 0.4% with a standard deviation equal to 3.0%. The rates of deviations larger than 5 and 7% were 9.9 and 2.6%, respectively. When considering the same data taking the average deviation in the case of opposed beams, the SD became 2.6% and the rates of deviations larger than 5 and 7%, respectively, 5.2 and 0.8%. When dividing the beams according to their orientation, significantly higher rates of large deviations (>5 and 7%) were found for oblique and posterior-anterior (PA) fields against lateral and anterior-posterior (AP) fields (P<0.05). Similarly, higher rates of large deviations were found for wedged fields against unwedged fields (P<0.03) and for blocked fields against unblocked fields (P<0.01). When dividing the data according to the anatomical district, accuracy was worse for breast (mean deviation 0.1%, 1 SD: 3.5%) and neck AP-PA fields (mean deviation 1%, 1 SD: 3,4%). Better accuracy was found for vertebrae (0.1%, 1 SD 2. 1%) and brain patients (-0.7%, 1 SD: 2.6%). During the considered period, in vivo dosimetry was also able to promptly detect a systematic error caused by a wrong resetting of the simulator height couch indicator, with a consequent error in the estimate of patient thickness of about 4 cm. CONCLUSIONS: In our experience, systematic in vivo dosimetry demonstrated to be a valid tool for quality assurance, both in detecting systematic errors which may escape the data transfer/MU calculation check and in giving an effective way of estimating the accuracy of treatment delivery.

Cohort Studies↗
PubMed1999

1D dynamic beam modulation: methods to counteract inertia effects.

Dynamic modulation can be affected by inaccuracies when the required acceleration is larger than the highest allowed by the mechanical characteristics of the whole apparatus. In this study, inertia effects have been investigated with regard to the single absorber 1D modulation, analysing primarily how the acceleration performed by the modulating system affects the realization of 'single absorber' fluence profiles and the type of correction which could be devised. The observed percentage deviations from desired modulation at the lowest fluence coordinate of single minimum fluence profiles, when no correction is applied, were almost negligible for 'easy' modulations of the incident fluence (i.e. slow gradients); deviations became increasingly relevant as the moving absorber executed steeper gradients (a 17.6% higher dose being delivered in the minimum position when a 0.2 modulation is required). By applying the proposed corrections, the single absorber performances were improved to a satisfactory level, with a maximum deviation from desired modulation in the minima within 1.6%.

Algorithms↗
PubMed1991

Tumor-associated trypsin inhibitor (TATI) in bone diseases.

The casual observation of high serum levels in (TATI) of tumor associated trypsin inhibitor in patients with osteosarcoma inspired us to evaluate the use of this peptide in the diagnosis of various bone diseases. We determined the serum concentrations of TATI in 35 patients with various bone diseases, i.e. degenerative diseases, bone metastasis and osteosarcomas. The cut off, determined as the 99th percentile of TATI serum levels in healthy volunteers was 32 micrograms/l. TATI has a better sensitivity in osteosarcomas (83%) than in metastatic bone diseases (33%). Its specificity in non-malignant bone diseases was not exceptional (82%). This is probably because TATI may also behave as on acute phase protein, the levels of which can rise in non-malignant diseases and also as a result of a tissue reaction in primary bone tumors.

Biomarkers, Tumor↗
PubMed1990

Arthrography of the prosthesetized painful hip: the importance of imaging and functional testing.

Thirty-four patients with painful prosthesetized hips were submitted to arthrography in order to evaluate the correlation between pain and the anatomical situation between the implants and the host bone. By injecting a local anaesthetic together with the contrast medium it was possible to perform functional tests comprising passive movements of the hip and full weightbearing for at least 5 minutes in order to ascertain whether or not the pain persisted. This yielded different results varying from total relief to persistence, depending on the type of mobilisation demonstrated by arthrography. In particular, pain was reduced in cases of mobilisation of the acetabular component, and persisted when mobilisation was in the femoral component. A correlation between functional testing, arthrography and bacteriological examination for possible low grade infection allowed for a closer study of the origin of pain, and more accurate planning of surgery when re-prosthesetization was being considered.

Aged↗
PubMed1989

Metal cementless prosthesis for vertebral body replacement of metastatic malignant disease of the cervical spine.

Sixteen patients affected with metastatic malignant disease of the cervical spine underwent cervical vertebral body replacement with an original metal cementless prosthesis. In all cases there was immediate spine stability postoperatively and pain relief. All patients were able to walk within a few days postoperatively without any rigid external support. Follow-up roentgenograms have shown nonprosthetic mobilization.

Adult↗
PubMed1987

[A case of giant lumbar neurinoma].

A rare case of a giant extradural neurinoma of the IV lumbar root with an anterior development and a soft neurological picture is reported. The Authors stress the important role of CT both in the neurinoma diagnosis and in the correct preoperative evaluation of its extension and its relationship with contiguous organs.

Female↗
PubMed1986

The surgical treatment of cervical metastases.

The basic problem in dealing with metastatic deposits in the cervical spine is to treat the lesion in time, that is, prior to the onset of radicular or medullary involvement. This is always progressive and seriously affects the quality of remaining life in these patients. Early surgical intervention, in fact, makes it possible to free these patients from the prolonged use of orthoses which are often badly tolerated, facilitates easy nursing and often avoids or significantly reduces the pain due to these secondary lesions, so restoring a quality of residual life which is acceptable even in the context of neoplastic disease. After reviewing the world literature and the proposals of various authors, we present our own experience in 28 surgically treated cases. The advantages and disadvantages of the various techniques are discussed. Finally, a flexible metallic cervical prosthesis designed by the authors is presented. This is a shock-absorbent device which is fixed without cement.

Adult↗