This work reports a method based on correlation functions to convert EPID transit signals into in vivo dose values at the isocenter point, D iso, of dynamic IMRT beams supplied by Varian linac. Dose reconstruction for intensity-modulated beams required significant corrections of EPID response, due to the X-ray component transmitted through multileaf collimator. The algorithm was formulated using a set of simulated IMRT beams.
View Article and Find Full Text PDFThe aim of this study was to report early clinical experience in stereotactic body radiosurgery (SBRS) delivered using volumetric intensity modulated arc therapy (VMAT) in patients with primary or metastatic tumors in various extra-cranial body sites. Each enrolled subject was included in a different phase I study arm, depending on the tumor site and the disease stage (lung, liver, bone, metastatic), and sequentially assigned to a particular dose level. Technical feasibility and dosimetric results were investigated.
View Article and Find Full Text PDFAim: To report the acute toxicity of a hypofractionated regimen of intensity-modulated radiotherapy with simultaneous integrated boost (SIB-IMRT) to the pelvic nodes and the prostatic bed after radical prostatectomy.
Patients And Methods: Patients with prostate adenocarcinoma at high risk of relapse after radical prostatectomy or with biochemical relapse were deemed eligible for study. SIB-IMRT was prescribed to the whole pelvis (45-Gy delivered in 1.
Aims And Background: The aim of this report was to investigate the feasibility in terms of treatment time prolongation of an on-line no-action level correction protocol, based on daily electronic portal image verification.
Methods And Study Design: The occupation of a linear accelerator (LINAC) delivering 3-D conformal treatments was monitored for two weeks (from Monday to Friday, 10 working days). An electronic portal image device I-View (Elekta, UK) was used for setup verification.
We report a case of penile metastases from recurrent prostatic adenocarcinoma that was the first sign of a widespread metastatic disease in the absence of any increase in prostate-specific antigen (PSA) level. In April 2011, an 80-year-old man presented to our Radiotherapy Unit with multiple palpable hard nodules in the penis, dysuria, and moderate perineal pain, 7 years after he had received radiotherapy for prostate cancer. Nodules in the penis had appeared in February 2011.
View Article and Find Full Text PDFInt J Radiat Oncol Biol Phys
November 2012
Purpose: To define the maximum tolerated dose (MTD) of a SHort-course Accelerated whole brain RadiatiON therapy (SHARON) in the treatment of patients with multiple brain metastases.
Methods And Materials: A phase 1 trial in 4 dose-escalation steps was designed: 12 Gy (3 Gy per fraction), 14 Gy (3.5 Gy per fraction), 16 Gy (4 Gy per fraction), and 18 Gy (4.
Background: We performed a dose-escalation trial to determine the maximum tolerated dose (MTD) of intensity-modulated radiotherapy (IMRT) with standard concurrent and sequential-dose temozolomide (TMZ) in patients with glioblastoma multiforme.
Methods: Histologically proven glioblastoma patients underwent IMRT dose escalation. IMRT was delivered over 5 weeks with the simultaneous integrated boost (SIB) technique to the two planning target volumes (PTVs) defined by adding 5-mm margin to the respective clinical target volumes (CTVs).
The aim of this study was to report the feasibility of volumetric-modulated arc therapy (VMAT) in the postoperative irradiation of the vaginal vault. Moreover, the VMAT technique was compared with 3D conformal radiotherapy (3D-CRT) and fixed-field intensity-modulated radiotherapy (IMRT), in terms of target coverage and organs at risk sparing. The number of monitor units and the delivery time were analyzed to score the treatment efficiency.
View Article and Find Full Text PDFBackground And Purpose: Late rectal complications are assessed according to different scoring systems. Endoscopy can provide a more sensitive estimation of early radiation damage. The aim of this paper is to investigate the correlation between dosimetric parameters and rectal mucosal changes after radiotherapy (RT).
View Article and Find Full Text PDFBackground: Radiotherapy (RT) is widely used in the treatment of pancreatic cancer. Currently, recommendation has been given for the delineation of the clinical target volume (CTV) in adjuvant RT. Based on recently reviewed pathologic data, the aim of this study is to propose criteria for the CTV definition and delineation including elective nodal irradiation (ENI) in the preoperative and definitive treatment of pancreatic cancer.
View Article and Find Full Text PDFObjective: To report the Phase II study final results in terms of pathological complete response (pCR) and complications in locally advanced cervical carcinoma (LACC) patients treated with chemoradiation (CT/RT) regimen based on accelerated fractionation, nodal extended fields and adjuvant radical surgery.
Methods: The sample size was quantified according to published data which shows that CT/RT followed by radical surgery in LACC patients provides a pCR rate above 45%. The 2-stage design by Simon was used to test the null hypothesis that the true pCR would improve by above 20%.
Purpose: To predict the grade and incidence of late clinical rectal toxicity through short-term (1 year) mucosal alterations.
Methods And Materials: Patients with prostate adenocarcinoma treated with curative or adjuvant radiotherapy underwent proctoscopy a year after the course of radiotherapy. Mucosal changes were classified by the Vienna Rectoscopy Score (VRS).
Aim: To analyze the results of extracranial stereotactic radiotherapy (ESRT) experience in pancreatic cancer patients.
Methods: Four noncoplanar fixed beams were used in all patients.
Results: Analysis of 16 patients was carried out.
J Appl Clin Med Phys
November 2011
A practical and accurate generalized procedure to reconstruct the isocenter dose D(iso) for 3D conformal radiotherapy (3DCRT) has been developed for X-ray open beams supplied by linacs of different manufacturers and equipped with aSi electronic portal imaging devices (aSi EPIDs). This paper reports an extension of the method, to be applied at the wedged X-ray beams characterized by the wedge attenuation factor W(AF). Using water-equivalent solid phantoms (SPs) of different thicknesses, w, and photon square fields of sizes, L, the generalized midplane doses D(0)(W(AF), w/2,L) and generalized transit signals s(t)(0)(W(AF),w,L) by 38 beams of six different linacs were determined.
View Article and Find Full Text PDFClin Oncol (R Coll Radiol)
May 2012
Aims: To report the feasibility of volumetric modulated arc therapy (VMAT) for neoadjuvant radiotherapy in locally advanced rectal cancer in a dose-escalation protocol and simultaneous integrated boost (SIB) approach. Moreover, the VMAT technique was compared with three-dimensional conformal radiotherapy (3D-CRT) and fixed-field intensity modulated radiotherapy (IMRT), in terms of target coverage and irradiation of organs at risk.
Materials And Methods: Eight patients with locally advanced rectal cancer were treated with the SIB-VMAT technique.
The purpose was to compare the dosimetric results observed in 201 breast cancer patients submitted to tangential forward intensity-modulated radiation therapy (IMRT) with those observed in 131 patients treated with a standard wedged 3D technique for postoperative treatment of whole breast, according to breast size and supraclavicular node irradiation. Following dosimetric parameters were used for the comparison: D(max), D(min), D(mean), V(95%) and V(107%) for the irradiated volume; D(max), D(mean), V(80%) and V(95%) for the ipsilateral lung; D(max), D(mean), V(80%) and V(95%) for the heart. Stratification was made according to breast size and supraclavicular (SCV) nodal irradiation.
View Article and Find Full Text PDFObjectives: To determine the recommended phase II dose of postoperative accelerated intensity modulated radiotherapy (IMRT) for prostate cancer.
Material And Methods: Step and shoot IMRT with simultaneous integrated boost (SIB) was delivered in 25 fractions over 5 weeks to patients with high risk resected prostate adenocarcinoma (stage pT3-4 and/or positive surgical margins). Pelvic nodes received 45 Gy at 1.
The accuracy and reproducibility of endometrial carcinoma treatment with intensity-modulated radiotherapy (IMRT) was assessed by means of in vivo dosimetry. Six patients who had previously undergone radical hysterectomy for endometrial carcinoma were treated with IMRT using a vaginal applicator with radio-opaque fiducial markers. An ion-chamber inserted into the applicator supplied an endocavitary in vivo dosimetry for quality assurance purposes.
View Article and Find Full Text PDFObjectives: To evaluate the feasibility of intensity-modulated radiotherapy with simultaneous integrated boost to the dominant intraprostatic lesion for definitive treatment of prostate cancer.
Materials And Methods: Patients were deemed eligible for the study if they had histologically proven stage cT2-T3 N0M0 prostate adenocarcinoma. In addition <20% risk of lymph nodal involvement according to Roach formula, was required for enrollment.
In-vivo dosimetry techniques are currently being applied only by a few Centers because they require time-consuming implementation measurements, and workload for detector positioning and data analysis. The transit in-vivo dosimetry performed by the electronic portal imaging device (EPID) avoids the problem of solid-state detector positioning on the patient. Moreover, the dosimetric characterization of the recent Elekta aSi EPIDs in terms of signal stability and linearity make these detectors useful for the transit in-vivo dosimetry with 6, 10 and 15 MV photon beams.
View Article and Find Full Text PDFThe transit in vivo dosimetry performed by the Electronic Portal Imaging Device (EPID), avoids the problem of solid-state detector positioning on the patient. Moreover, the dosimetric characterization of the recent Elekta aSi EPIDs in terms of signal stability and linearity enables these detectors adaptable for the transit in vivo dosimetry with 6, 10 and 15 MV photon beams. However, the implementation of the EPID transit dosimetry requires several measurements.
View Article and Find Full Text PDFAn electronic portal imaging device (EPID) is an effective detector for in vivo transit dosimetry. In fact, it supplies two-dimensional information, does not require special efforts to be used during patient treatment, and can supply data in real time. In the present paper, a new procedure has been proposed to improve the EPID in vivo dosimetry accuracy by taking into account the patient setup variations.
View Article and Find Full Text PDFA practical and accurate generalized in vivo dosimetry procedure has been implemented for Siemens linacs supplying 6, 10, and 15 MV photon beams, equipped with aSi electronic portal imaging devices (EPIDs). The in vivo dosimetry method makes use of correlation ratios between EPID transit signal, s (t) (0) (TPR,w,L), and phantom mid-plane dose, D (0)(TPR,w,L), as functions of phantom thickness, w, square field dimensions, L, and tissue-phantom ratio TPR(20,10). The s (t) (0) (TPR,w,L) and D (0)(TPR,w,L) values were defined to be independent of the EPID sensitivity and monitor unit calibration, while their dependence on TPR(20,10) was investigated to determine a set of generalized correlation ratios to be used for beams with TPR(20,10) falling in the examined range.
View Article and Find Full Text PDFA 77-year-old male patient with unresected malignant pleural mesothelioma, clinical stage T3N0M0 according to the New International Staging System for Diffuse Malignant Pleural Mesothelioma, received intensity-modulated radiotherapy (IMRT) with a simultaneous integrated boost (SIB) after 6 cycles of chemotherapy with cisplatin and pemetrexed. SIB-IMRT delivered 40.5 Gy (1.
View Article and Find Full Text PDFPurpose: To evaluate the corneal changes of patients with Crohn's disease (CD) using confocal microscopy and to investigate the association among confocal parameters and CD activity and CD treatment.
Methods: Thirty consecutive patients (age: 42 ± 12 years; 19 women and 11 men) affected by CD and 30 control eyes (age matched and gender matched) underwent an ophthalmic examination and, in 1 eye chosen at random, confocal microscopy of the central cornea using the cornea module of Heidelberg Retina Tomograph. The following confocal parameters were evaluated: density of basal epithelial cells, epithelial dendritic cells, anterior and posterior stromal keratocytes, and endothelial cells; the subbasal plexus was assessed for number and tortuosity of the nerve fibers.