129 research outputs found
Comments on "postoperative intensity-modulated radiotherapy following surgery for oral cavity squamous cell carcinoma : patterns of failure" by Chan and Coll
No full textComments on "Postoperative intensity-modulated radiotherapy following surgery for oral cavity squamous cell carcinoma: Patterns of failure" by Chan and Coll
No full textA procedure to mathematically amend possible thickness disuniformities in gel-layer dosimetry
No full textThe continuous development of conformal radiotherapies requires a corresponding improvement of dosimetric techniques. Fricke gel-layer dosimetry, coupled with a suitably developed software, has proven to be a reliable technique for 3D absorbed dose distribution verification. The method is based on the evaluation of the light transmitted by gel-layers due to the fact that th optical density difference between irradiated and non irraddiated dosimeters is proportional to the absorbed dose. Measurement are performed by means of a planar illumination source and a computer-controlled CCD camera. Recently, adoption of gel layers with increased superficial dimensions has evidenced a possible thickness disuniformity of layers, thus introducing a new source of measurement inaccuracy. In this work, a method to mathematically amend this possible source of error is proposed. Dose profiles along the central axis of phantoms irradiated with X-ray therapy and Boron Neutron Capture Therapy fields, obtained with and without the application of the proposed correction procedure, were compared with ionization chamber measurements and Monte Carlo simulations, respectively. The obtained results show a good reliability of the proposed procedure
Radioprotezione in ortopedia pediatrica: considerazioni sul depistage radiologico della displasia congenita dell'anca e proposta originale per la risoluzione del problema radioprotezionistico
No full textFricke gel-layer dosimetry in high dose-rate brachytherapy
No full textThe aim of this study was to evaluate the reliability of Fricke gel-layer dosimeters for the measurement of in-phantom dose distributions produced by a 192Ir brachytherapy source. The doses obtained were compared to measurements performed with thermoluminescent dosimeters and treatment planning calculations. Frickegel-layer dosimeters have proven to be a promising tool to measure three-dimensional dose distributions in high dose-rate brachytherapy
Pre-implant magnetic resonance and transrectal ultrasound imaging in high-dose-rate prostate brachytherapy : comparison of prostate volumes, craniocaudal extents, and contours
No full textPurpose: The purpose of this study was to compare the prostate contours drawn by two radiation oncologists and one radiologist on magnetic resonance (MR) and transrectal ultrasound (TRUS) images. TRUS intra- and inter-fraction variability as well as TRUS vs. MR inter-modality and inter-operator variability were studied. Material and methods: Thirty patients affected by localized prostate cancer and treated with interstitial high-dose-rate (HDR) prostate brachytherapy at the National Cancer Institute in Milan were included in this study. Twenty-five patients received an exclusive two-fraction (14 Gy/fraction) treatment, while the other 5 received a single 14 Gy fraction as a boost after external beam radiotherapy. The prostate was contoured on TRUS images acquired before (virtual US) and after (real US) needle implant by two radiation oncologists, whereas on MR prostate was independently contoured by the same radiation oncologists (MR1, MR2) and by a dedicated radiologist (MR3). Absolute differences of prostate volumes (∆V) and craniocaudal extents (∆dz) were evaluated. The Dice's coefficient (DC) was calculated to quantify spatial overlap between MR contours. Results: Significant difference was found between Vvirtual and Vlive (p < 0.001) for the first treatment fractions and between VMR1 and VMR2 (p = 0.043). Significant difference between cranio-caudal extents was found between dzvirtual and dzlive (p < 0.033) for the first treatment fractions, between dzvirtual of the first treatment fractions and dzMR1 (p < 0.001) and between dzMR1 and dzMR3 (p < 0.01). Oedema might be responsible for some of the changes in US volumes. Average DC values resulting from the comparison MR1 vs. MR2, MR1 vs. MR3 and MR2 vs. MR3 were 0.95 ± 0.04 (range, 0.82-0.99), 0.87 ± 0.04 (range, 0.73-0.91) and 0.87 ± 0.04 (range, 0.72-0.91), respectively. Conclusions: Our results demonstrate the importance of a multiprofessional approach to TRUS-guided HDR prostate brachytherapy. Specific training in MR and US prostate imaging is recommended for centers that are unfamiliar with HDR prostate brachytherapy
Feasibility and activity of docetaxel, cisplatinum and 5-fluorouracil induction chemotherapy followed by concurrent chemo-radiotherapy (including IMRT) in locally advanced undifferentiated nasopharyngeal cancer (LANPC)
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