High dose craniospinal irradiation as independent risk factor of permanent alopecia in childhood medulloblastoma survivors: cohort study and literature review.

PURPOSE: Our aim was to determine the main risk factors related to the occurrence of permanent alopecia in childhood medulloblastoma (MB) survivors. METHODS: We retrospectively analyzed the clinical features of all consecutive MB survivors treated at our institute. We divided the patients into 3 groups depending on the craniospinal irradiation (CSI) dose received and defined permanent alopecia first in terms of the skin region affected (whole scalp and nape region), then on the basis of the toxicity degree (G). Any relationship between permanent alopecia and other characteristics was investigated by a univariate and multivariate analysis and Odds ratio (OR) with confidence interval (CI) was reported. RESULTS: We included 41 patients with a mean10-year follow-up. High dose CSI resulted as an independent factor leading to permanent hair loss in both groups: alopecia of the whole scalp (G1 p-value 0.030, G2 p-value 0.003) and of the nape region (G1 p-value 0.038, G2 p-value 0.006). The posterior cranial fossa (PCF) boost volume and dose were not significant factors at multivariate analysis neither in permanent hair loss of the whole scalp nor only in the nuchal region. CONCLUSION: In pediatric patients with MB, the development of permanent alopecia seems to depend only on the CSI dose ≥ 36 Gy. Acute damage to the hair follicle is dose dependent, but in terms of late side effects, constant and homogeneous daily irradiation of a large volume may have a stronger effect than a higher but focal dose of radiotherapy.

Dosimetric analysis of Tomotherapy-based intracranial stereotactic radiosurgery of brain metastasis.

PURPOSE: This paper analyzes Tomotherapy-based intracranial stereotactic radiosurgery (HTSRS) of brain metastasis targeting two end-points: 1) evaluation of dose homogeneity, conformity and gradient scores for single and multiple lesions and 2) assay of dosimetric criticality of completion of HTSRS procedures. METHODS: 42 treatment plans of 33 patients (53 brain lesions) treated with HTSRS were analyzed. Dose to healthy brain, homogeneity, conformity and gradient indexes were evaluated for each lesion. Influence of Field Length and multiple lesions cross-talk effect were assessed. Treatment interruption and completion was investigated using radiochromic films in order to examine the delivered dose and its robustness to patient intrafraction movement. RESULTS: The average dose homogeneity index was 1.04 ±â€¯0.02 (SD). Average dose conformity and gradient score indexes were 1.4 ±â€¯0.2 and 50 ±â€¯14 respectively. We found a strong correlation of the dose to healthy brain and conformity and gradient indexes with target(s) volume for which analytical functions were obtained. Field Length and cross-talk effect were significantly correlated with poor gradient scores, but were found not to affect dose conformity. CONCLUSIONS: Homogeneity and conformity of HTSRS plans achieved excellent scores, while dose falloff and dose to healthy brain were slightly larger when compared with non-coplanar SRS techniques. Care should be given if treating large (>3 cc) or multiple near in-plane lesions in order to reduce dose to healthy brain. Analysis of interrupted treatments suggests splitting HTSRS treatments in two consecutive fractions in order to prevent target miss and overdosage due to patient intrafraction movement.

Estimation of percentage breast tissue density: comparison between digital mammography (2D full field digital mammography) and digital breast tomosynthesis according to different BI-RADS categories.

OBJECTIVE: To compare breast density estimated from two-dimensional full-field digital mammography (2D FFDM) and from digital breast tomosynthesis (DBT) according to different Breast Imaging-Reporting and Data System (BI-RADS) categories, using automated software. METHODS: Institutional review board approval and written informed patient consent were obtained. DBT and 2D FFDM were performed in the same patients to allow within-patient comparison. A total of 160 consecutive patients (mean age: 50±14 years; mean body mass index: 22±3) were included to create paired data sets of 40 patients for each BI-RADS category. Automatic software (MedDensity(©), developed by Giulio Tagliafico) was used to compare the percentage breast density between DBT and 2D FFDM. The estimated breast percentage density obtained using DBT and 2D FFDM was examined for correlation with the radiologists' visual BI-RADS density classification. RESULTS: The 2D FFDM differed from DBT by 16.0% in BI-RADS Category 1, by 11.9% in Category 2, by 3.5% in Category 3 and by 18.1% in Category 4. These differences were highly significant (p<0.0001). There was a good correlation between the BI-RADS categories and the density evaluated using 2D FFDM and DBT (r=0.56, p<0.01 and r=0.48, p<0.01, respectively). CONCLUSION: Using DBT, breast density values were lower than those obtained using 2D FFDM, with a non-linear relationship across the BI-RADS categories. These data are relevant for clinical practice and research studies using density in determining the risk. ADVANCES IN KNOWLEDGE: On DBT, breast density values were lower than with 2D FFDM, with a non-linear relationship across the classical BI-RADS categories.

A two-step selection of breast cancer patients candidates for exclusive IORT with electrons: a mono-institutional experience.

AIM: To assess the impact of a two-step multiparameter selection on the actual enrollment of women with breast cancer into a prospective intraoperative radiotherapy (IORT) trial. PATIENTS AND METHODS: From September 2009, a prospective clinical trial was started in order to deliver adjuvant exclusive single -fraction IORT to patients with early breast cancer. To select patients meeting suitable eligibility criteria for the clinical trial, a two-step decision process was developed: at pre-surgical examination (first step) and during surgery (second step). RESULTS: A series of 464 patients with breast cancer was analysed: at the first step, out of 464 patients, 333 (71%) were considered eligible for the IORT protocol; at the second step, out of 333 patients, 199 (60%) met the eligibility criteria and received the IORT fraction according to the criteria of the controlled trial. CONCLUSION: In our experience, the ultimate rate of patients who enrolled in the IORT clinical trial after the two-step decision process was 43%.

The determination of dose characteristics of ruthenium ophthalmic applicators using radiochromic film.

Ruthenium ophthalmic applicators are energetic beta ray sources, supplied in several shapes and dimensions, and used in intraocular tumor therapy. Because of their small dimensions, the determination of dosimetric characteristics represents a technical challenge. We developed a semiautomatic method to define surface dose, dose distribution, and percentage depth dose of such applicators using radiochromic dosimetric media. These detectors consist of a thin (7 microns) radiation sensitive layer on polyester base (100 microns total thickness) changing color as a function of radiation exposure. Transmission images of exposed films were then grabbed with a TV-digitizer system to obtain a gray-level image from which dosimetric characteristics such as isodose distribution, dose values, and homogeneity of nuclide distribution were derived. Good agreement between experimental results and Monte Carlo simulation performed using the GEANT 3 code, appear to be a confirmation of the validity of the method. Moreover while manufacturer specifications of absolute and relative dose rates present a standard deviation error of +/- 30% on dose rate and +/- 6% on accuracy of relative dose values, the proposed method reduces the errors to +/- 10% and +/- 4%, respectively.

Radio-hyperthermia in post-surgical recurrence of melanoma.

AIMS AND BACKGROUND: Malignant melanoma is one of the most radioresistant tumors. It can be treated with combinated hyperthermia and radiation therapy. METHODS: From January 1991 through June 1992, 7 patients, 1 male and 6 female, aged 40-88 years (mean 75), with skin and nodal post-surgical recurrences of melanoma, were treated with a combination of radiation therapy and hyperthermia. Two patients presented systemic disease when they reached our observation, but all of them were without symptoms. None of them underwent surgical excision of the recurrence before or during thermoradiotherapy. None received chemotherapy for these recurrences or had received radiotherapy in the past. They were irradiated with electron beams, with electron energies selected according to the depth of the lesions. The total dose was 40 Gy in 10 fractions in 5 weeks. Hyperthermia was administered for 10 minutes to 1 hour after irradiation. An inductive method of radiofrequency heating at 434 of 915 MHz was used depending on the depth of the lesions. In all of these treatments a ionized water bolus was used. The prescribed hyperthermic dose was 42 degrees C for half a hour. The treatments were carried out twice a week for 5 weeks. A fiberoptic multichannel thermometer was used for thermometry. RESULTS: Four patients (57%) achieved a complete response, 2 patients (29%) a partial response, and 1 patient (14%) stabilization. We found no correlation between tumor volume and response rate. Site effects and complications of the treatment were minimal (moderate erythema). CONCLUSIONS: Our results are in the wide range of values reported in the literature.

A personal dosimeter prototype for static magnetic fields.

A personal dosimeter prototype, for static magnetic fields with three Hall probes, has been designed and built to provide a reliable instrument for long-term analysis. The probe output signals, proportional to the magnetic flux density components of the vector B, are filtered, sampled, and stored in a buffer memory sufficient to cover a whole worker shift. The data sampling rate is high enough to record the operator movements within the fringes of the magnetic field. The content of the buffer memory is then transferred on a personal computer and registered on individual dosimetric cards. The data can be used for personal exposure monitoring.

Molecular packing parameters of bipolar lipids.

The bipolar lipid fractions extracted from the thermophilic archaeobacterium Sulfolobus solfataricus have different chemical structures and geometrical shapes. The conditions which lead to the formation of vesicles were investigated in order to study the self-assembly of these molecules. Such conditions are fulfilled when an appropriate mixture of two different molecular species (both bipolar or bipolar and monopolar) is used. According to the theory introduced by Israelachvili and co-workers, lipid self-assembly results from the balance of interaction free energy, entropy and molecular geometry. We have shown that this theory can be extended to bipolar lipids, in spite of their more complex nature, and the experimental results obtained combining 1H-NMR, light scattering and entrapped volume techniques closely match theoretical expectations. To carry out calculations, it was necessary to introduce hypotheses about the disposition of bipolar molecules in the vesicle membrane. These hypotheses have been tested indirectly by measuring the transport properties mediated by carriers or channels, whose transport mechanism can be considered to be a probe of the membrane structure.