Delivering RapidArc®: A comprehensive study on accuracy and long term stability.

PURPOSE: To establish the reliability and accuracy of a UNIQUE Linac in delivering RapidArc treatments and assess its long term stability. MATERIALS AND METHODS: UNIQUE performance was monitored and analyzed for a period of nearly two years. 2280 Dynalog files, related to 179 clinical RapidArc treatments were collected. Different tumor sites and dose scheduling were included, covering the full range of our treatment plans. Statistical distributions of MLC motion error, gantry rotation error and MU delivery error were evaluated. The stochastic and systematic nature of each error was investigated together with their variation in time. RESULTS: All the delivery errors are found to be small and more stringent tolerances than those proposed by TG142 are suggested. Unlike MLC positional errors, where a linear relationship with leaf speed holds, other Volumetric Modulated Arc Therapy (VMAT) parameters reveal a random nature and, consequently, a reduced clinical relevance. MLC errors are linearly related only to leaf speed no matter the shape of the MLC apertures. Gantry rotation and MU delivery are as accurate as major competing Linacs. UNIQUE was found to be reliable and accurate throughout the investigation period, regardless of the specific tumor sites and fractionation schemes. CONCLUSIONS: The accuracy of RapidArc treatments delivered with UNIQUE has been established. The stochastic nature of delivery errors is proven. Long term statistics of the delivery parameter errors do not show significant variations, confirming the reliability of the VMAT delivery system.

Clinical impact of bacterial contamination of perfusion fluid in kidney transplantation.

Contamination of perfusion fluid (PF) could lead to serious infections in kidney transplant recipients. Preemptive therapy (PE-T) in case of yeast contamination of PF is mandatory. The usefulness of PE-T in presence of bacteria remains unclear. In this study we evaluated the incidence of PF bacterial contamination and the impact of PE-T on clinical outcome. Microbiological data of 290 PF and clinical data of the corresponding recipients collected in our hospital from January 2010 and December 2012 were analyzed. Recipients with bacterial contaminated PF (101) were divided in 3 groups: group 1 (n = 52) PE-T treated bacteria resistant to perioperative antibiotic prophylaxis (PAP), group 2 (n = 28) bacteria sensitive to PAP, group 3 (n = 21) PE-T-untreated bacteria resistant to PAP. Incidence of positive PF was 34.8 %, 50.4 % staphylococci, 9.9 % C. albicans. No significant differences in the rate of PF-related infections between the three groups were found. In conclusion, although PF contamination is frequent, the incidence of PF-related infections is very low. In addition, in this study PE-T did not help to reduce the rate of PF-related infection suggesting that a resonable reduction in the use of antibiotic terapy could be made. However, waiting for largest and prospective clinical trials to confirm our findings, a closely clinical and microbiologic monitoring of the recipient is highly recommended in case of PF contamination.

Simultaneous Liver-Kidney Transplantation in Adults: A Single-center Experience Comparing Results With Isolated Liver Transplantation.

BACKGROUND: After introduction of the Model for End-Stage Liver Disease (MELD) score in 2002, a worldwide increasing number of simultaneous liver-kidney transplantations (SLKTx) has been observed. However, organ shortage puts into question the allocation of 2 grafts to 1 recipient. This retrospective, single-center study compared SLKTx results with isolated liver transplantation (LTx). METHODS: Between 1995 and 2013, 37 SLKTx were performed in adult recipients. Every SLKTx was matched by donor age (±5 years) and transplantation date with 2 LTx (n = 74). Pretransplant, intraoperative, and post-transplant variables were collected; liver graft and patient survivals were calculated. RESULTS: As expected, donor age was similar in the 2 groups (median, 39.7 years), whereas serum creatinine level, glomerular filtration rate, and MELD and D-MELD (donor age*MELD) scores were significantly higher in the SLKTx group. SLKTx had longer waiting list time (P = .0034) as well as higher surgical difficulty, testified by more blood transfusions (P = .0083), increased use of classic caval reconstruction (P = .0024), and more frequent need of abdominal packing for bleeding control (P = .0003). In addition, duration of hospital stay (P < .0001), second-look surgery (P = .0082), post-transplant dialysis (P < .0001), and post-transplant infections (P = .04) were significantly greater in SLKTx group. Acute rejection episodes involving the liver were significantly less in SLKTx than in LTx (14% vs 41%; P = .0045). Liver graft and patient survival at 10 years after transplantation was similar in the 2 groups (liver graft: SLKTx, 80% vs LTx, 77% [P = .85]; patient: SLKTx, 86% vs LTx, 79% [P = .56]). CONCLUSIONS: Despite being technically challenging, SLKTx provided excellent long-term results and was shown to be an effective use of liver grafts.

Validation of a commercial TPS based on the VMC(++) Monte Carlo code for electron beams: commissioning and dosimetric comparison with EGSnrc in homogeneous and heterogeneous phantoms.

The aim of the present work was the validation of the VMC(++) Monte Carlo (MC) engine implemented in the Oncentra Masterplan (OMTPS) and used to calculate the dose distribution produced by the electron beams (energy 5-12 MeV) generated by the linear accelerator (linac) Primus (Siemens), shaped by a digital variable applicator (DEVA). The BEAMnrc/DOSXYZnrc (EGSnrc package) MC model of the linac head was used as a benchmark. Commissioning results for both MC codes were evaluated by means of 1D Gamma Analysis (2%, 2 mm), calculated with a home-made Matlab (The MathWorks) program, comparing the calculations with the measured profiles. The results of the commissioning of OMTPS were good [average gamma index (γ) > 97%]; some mismatches were found with large beams (size ≥ 15 cm). The optimization of the BEAMnrc model required to increase the beam exit window to match the calculated and measured profiles (final average γ > 98%). Then OMTPS dose distribution maps were compared with DOSXYZnrc with a 2D Gamma Analysis (3%, 3 mm), in 3 virtual water phantoms: (a) with an air step, (b) with an air insert, and (c) with a bone insert. The OMTPD and EGSnrc dose distributions with the air-water step phantom were in very high agreement (γ ∼ 99%), while for heterogeneous phantoms there were differences of about 9% in the air insert and of about 10-15% in the bone region. This is due to the Masterplan implementation of VMC(++) which reports the dose as "dose to water", instead of "dose to medium".

Fine needle aspiration of non-small cell lung cancer: current state and future perspective.

AThe emerging treatment revolution determined by the advent of new targeted therapies requires accurate tumour subtyping as a mandatory step in the clinical workup of patients with non-small cell lung carcinoma (NSCLC). As a result of advanced and inoperable disease or poor performance status, in many patients, minimally invasive procedures must be employed to obtain diagnostic material. Fine needle aspiration (FNA) is a valid and widely employed alternative to either tru-cut or open-sky biopsy. Indeed, cytological specimens are suitable for techniques such as immunocytochemistry, mutation and microRNA analysis, and may present advantages over small biopsies especially if cell blocks are prepared and attention is paid to cytomorphology and pre-analytic management of specimens at the time they are collected. These will allow the adequate stratification of patients into different diagnostic and prognostic classes.

Commissioning Siemens Virtual Wedges in the Oncentra MasterPlan treatment planning system using Gafchromic EBT film.

PURPOSE: Virtual Wedges were introduced in Siemens LINACs to improve the treatment workflow. The aim of the present work is the validation of dose calculation by MasterPlan-Oncentra treatment planning system for virtual wedged beams. METHODS: The Oncor Siemens accelerator installed in the authors' department produces 6 and 15 MV photon beams. At first, the consistency of VW LINAC production was tested and the EBT film measuring method was verified. This method is based on the scanner uniformity correction and absolute dose calibration as reported in literature. Then, the measured and calculated wedge factors and beam profiles are compared. For 15 degrees, 30 degrees, 45 degrees, and 60 degrees wedge angles, the wedge factors for different field sizes were measured by an ionization chamber and the dose profiles were acquired by Gafchromic EBT film. Both types of measurements were collected in isocentric condition. RESULTS: The comparison between measured and calculated VW factors shows discrepancies that increase with field size and angle. The OTP Enhanced algorithm produces better agreement with measurements than the Classic one, with improvement overall visible for large angles. The agreement between measured and planned beam profiles is within limits reported by the ESTRO Booklet No. 7 in terms of confidence limits. CONCLUSIONS: The MasterPlan-Oncentra treatment planning system determines wedge factors and VW profiles within the requested accuracy in the majority of treatment conditions. For big field dimensions and wedge angle, wedge factor accordance was worse, but it may be increased with an improvement of the LINAC dosimetric board calibration.

Life at depth: Photobacterium profundum genome sequence and expression analysis.

Deep-sea life requires adaptation to high pressure, an extreme yet common condition given that oceans cover 70% of Earth's surface and have an average depth of 3800 meters. Survival at such depths requires specific adaptation but, compared with other extreme conditions, high pressure has received little attention. Recently, Photobacterium profundum strain SS9 has been adopted as a model for piezophily. Here we report its genome sequence (6.4 megabase pairs) and transcriptome analysis. The results provide a first glimpse into the molecular basis for life in the largest portion of the biosphere, revealing high metabolic versatility.

[Analysis of recurrences following conservative treatment of breast carcinoma]. / Analisi delle recidive dopo trattamento conservativo del carcinoma mammario.

In the conservative treatment of early breast cancer, great attention must be paid to define the prognostic factors correlated with the local recurrence rate. The goal is to customize surgery, radiotherapy and chemotherapy to the risk predicted in every single patient. To investigate the impact of some prognostic factors in a group of patients treated with homogeneous treatment schedules, 251 women with UICC stage I or II breast cancer were examined in the Padua Radiotherapy Department from 1988 to 1990. All patients underwent conservative surgery consisting in quadrantectomy, axillary node dissection and radiotherapy. During a median follow-up period of 49.2 months, 12 patients presented a breast relapse (4.8%). In 4 patients the relapse occurred in the same quandrant as the primary lesion, whereas a different quadrant was involved in the other 8 patients. The relapse rate in women under 60 was 5% and 4.7% in older patients, with p = 0.73. In pT1 patients, the relapse rate was 4.5% and in pT2 patients it was 7.9% (p = 0.37). No significant difference was observed between pN- and pN+ patients (4.5% vs. 6.25%, p = 0.37). In our series, none of the studied factors significantly influenced breast relapse rates. The number of patients may be too little relative to the low rate of relapses. However, an unfavorable trend was observed in the patients under 60, in pT2 or pN+ patients, or in the patients with positive or unknown surgical margins.

Three-field isocentric technique for breast irradiation using individualized shielding blocks.

The three-field technique is the most common method used for breast and regional node treatment after conservative surgery. Several variants of this technique, which are characterized by complex geometrical problems, have been described. A possible simplification of this technique and the use of individualized shielding blocks both for anterior and for tangential fields is proposed, thus allowing for the simultaneous shielding of the half beam and the critical areas. Advantages of isocentrical techniques are thereby maintained, but the number of mechanical movements required is minimized and collimators and couch rotations are not needed. Patient set-up time is also greatly shortened. The accuracy of this technique has been verified using both photographic methods and thermoluminescent dosimetry.