Radiation survey around a Liac mobile electron linear accelerator for intraoperative radiation therapy

The aim of this study was to perform a detailed analysis of the air kerma values around a Liac mobile linear accelerator working in a conventional operating room (OR) for IORT. The Liac delivers electron beams at 4, 6, 8 and 10 MeV. A radiation survey to determine photon leakage and scatter consisted of air kerma measurements on a spherical surface of 1.5 m radius, centered on the titanium exit window of the accelerating structure. Measurements were taken using a 30 cm 3 calibrated cylindrical ion chamber in three orthogonal planes, at the maximum electron energy. For each point, 10 Gy was delivered. At selected points, the quality of x-ray radiation was determined by using lead sheets, and measurements were performed for all energies to investigate the energy dependence of stray radiation. The photon scatter contribution from the metallic internal patient-shielding in IORT, used to protect normal tissues underlying the target, was also evaluated. At seven locations outside the OR, the air kerma values derived from in-room measurements were compared to measurements directly performed using a survey meter. The results, for a delivere

Redox Proteomics in Aging Rat Brain: Involvement of Mitochondrial Reduced Glutathione Status and Mitochondrial Protein Oxidation in the Aging Process

Increasing evidence supports the notion that increased oxidative stress is a fundamental cause in the aging process and in neurodegenerative diseases. As a result, a decline in cognitive function is generally associated with brain aging. Reactive oxygen species (ROS) are highly reactive intermediates, which can modify proteins, nucleic acids, and polyunsaturated fatty acids, leading to neuronal damage. Because proteins are major components of biological systems and play key roles in a variety of cellular functions, oxidative damage to proteins represents a primary event observed in aging and age-related neurodegenerative disorders. In the present study, with a redox proteomics approach, we identified mitochondrial oxidatively modified proteins as a function of brain aging, specifically in those brain regions, such as cortex and hippocampus, that are commonly affected by the aging process. In all brain regions examined, many of the identified proteins were energy-related, such as pyruvate kinase, ATP synthase, aldolase, creatine kinase, and alpha-enolase. These alterations were associated with significant changes in both cytosolic and mitochondrial redox status in all brain regions analyzed. Our finding is in line with current literature postulating that free radical damage and decreased energy production are characteristic hallmarks of the aging process. In additon, our results further contribute to identifying common pathological pathways involved both in aging and in neurodegenerative disease development. (C) 2010 Wiley-Liss, Inc

Intraoperative radiotherapy for locally advanced prostate cancer: Treatment technique and ultra sound-based analysis of dose distribution

Background: To present the technique and dose distribution of intraoperative radiotherapy (IORT) for prostate cancer. Patients and Methods: Pelvic lymphadenectomy, prostate IORT and radical retropubic prostatectomy was performed in 11 prostate cancer patients. Prostate thickness and rectum depth were measured with intraoperative ultrasound. IORT was delivered by a mobile linear accelerator in the operating room (electron beam, 12 Gy at 90% isodose). Results: The mean preoperative probability of organ-confined disease was 10% (Memorial Sloan Kettering Cancer Center nomograms). Mean prostate thickness, width and length were 3.4 cm, 4.6 and 4.9 cm, respectively. Mean rectum depth was 3.3 cm. Mean doses to the posterior prostate capsule, 5-mm lateral prostate margins and at the subsequent uretheral stump area were 4.6 Gy, 8.7 Gy and 11.3 Gy, respectively. Maximum mean rectal dose was 4.9 Gy. Conclusion: IORT appeared a feasible approach for prostate cancer, showing a satisfactory dose coverage to the prostate bed with relatively low rectal dose. However, high variability in dose distribution calls for further study of patient selection criteria and dosimetry

Intra-fraction respiratory motion and baseline drift during breast Helical Tomotherapy

Background and purpose To investigate the intra-fraction breast motion during long-lasting treatments of breast cancer with Helical Tomotherapy by means of an optical tracking system. Materials and methods A set of seven radio-transparent passive markers was placed on the thoraco-abdominal surface of twenty breast cancer patients and tracked by an infrared tracking system. A continuous non-invasive monitoring of intra-fraction motion from patient setup verification and correction to the end of radiation delivery was thus obtained. The measured displacements were analysed in terms of cyclic respiratory motion and slow baseline drift. Results The average monitoring time per patient was 15.57 min. The breathing amplitude of the chest was less than 2 mm, on average, along all anatomical directions. The baseline drift of the body led to more significant setup uncertainties than the respiratory motion. The main intra-fraction baseline drifts were in posterior and inferior directions and occurred within the first eight minutes of monitoring. Considering the intra-fraction motion only, the resultant clinical-to-planning target volume safety margins are highly patient-specific and largely anisotropic. Conclusion The non-respiratory motion occurring during prolonged treatments induces notable uncertainties. Non-invasive continuous monitoring of patient setup variations including baseline drifts is recommended in order to minimize dosimetric deviations, which might jeopardize the therapeutic ratio between target coverage and the sparing of organs at risk

Intraoperative radiotherapy for locally advanced prostate cancer: The experience of the European institute of oncology

INTRODUCTION AND OBJECTIVE: To present the technique adopted for intraoperative radiotherapy (IORT) for locally advanced prostate cancer. METHODS: Between June 2005 and February 2007, 24 patients (pts) with non-metastatic prostate cancer were treated with IORT before prostatectomy as part of their surgical procedure. Median DJHZDV\HDUVUDQJH7HQSWVZHUHFODVVL\ubfHGDV 7FSWVDV\u9577KHPHGLDQL36$ZDVQJPODQGWKH median bioptic Gleason Score was 7. According to NCCN 2007, risk group distribution was as follows: intermediate risk 2 pts (8.33%) and high risk 22 pts (91.67%). A total of 11 pts (45.83%) were treated with neoadjuvant hormones. Immediately before IORT prostate dimensions and rectum depth were measured with intraoperative ultrasound. IORT was delivered by a mobile linear accelerator in the operating room. The prescribed dose was 12 Gy at the 90% isodose. In vivo dosimetry was performed. Three months later, postoperative external beam radiotherapy (EBRT) of 45-50,4 Gy in 25-28 fractions was prescribed to the prostatic bed alone and whole pelvis in case of pT3-4 pN0 and pN1, respectively. RESULTS: According to the MSKCC nomograms, the mean SUHRSHUDWLYHSUREDELOLW\RIRUJDQFRQ\ubfQHGGLVHDVHH[WUDFDSVXODUGLVHDVH and lymph node involvement were 8%, 40% and 25% respectively. 3RVWRSHUDWLYHKLVWRORJLFDO\ubfQGLQJVZHUHDVIROORZVPHGLDQ*6UDQJH 6-9), pT2 7 pts (29,2%), pT3 14 pts (58,3), pT4 3 (12,5%), pN0 12 pts, S1SWV2UJDQFRQ\ubfQHGGLVHDVHS7S15ZDVGLDJQRVHGLQ pts (16.6%) and no further radiation treatment was prescribed. Based RQWKHGH\ubfQLWLYHKLVWRORJLFDOUHSRUWVSRVWRSHUDWLYHSHOYLFDQGSURVWDWLF bed EBRT is planned in 12 and 8 pts, respectively. After a median follow up of 9.2 months (range 3.3-15.7) only 1 patient had evidence of biochemical relapse. No patients had major acute rectal toxicity. No acute urinary toxicity was observed in 6 patients, 17 patients had G1 toxicity. No increased risk of urinary incontinence was recorded. CONCLUSIONS: IORT delivered before prostatectomy appeared a feasible and safe approach for prostate cancer, showing a satisfactory dose coverage to the prostate bed with relatively low rectal wall dose. Longer follow-up is needed to evaluate late toxicity and clinical control