Entity

Time filter

Source Type

Pardubice, Czech Republic

Rezacova M.,Charles University | Rudolfova G.,Charles University | Tichy A.,Charles University | Tichy A.,University of Defence at Brno | And 7 more authors.
Radiation Research | Year: 2011

The purpose of this work was to determine how fractionated radiation used in the treatment of tumors affects the ability of cancer as well as normal cells to repair induced DNA double-strand breaks (DSBs) and how cells that have lost this ability die. Lymphocytic leukemia cells (MOLT4) were used as an experimental model, and the results were compared to those for normal cell types. The results show that cancer and normal cells were mostly unable to repair all DSBs before the next radiation dose induced new DNA damage. Accumulation of DSBs was observed in normal human fibroblasts and healthy lymphocytes irradiated in vitro after the second radiation dose. The lymphocytic leukemia cells irradiated with 4 ×à - 1 Gy and a single dose of 4 Gy had very similar survival; however, there was a big difference between human fibroblasts irradiated with 4 ×à - 1.5 Gy and a single dose of 6 Gy. These results suggest that exponentially growing lymphocytic leukemia cells, similar to rapidly proliferating tumors, are not very sensitive to fraction size, in contrast to the more slowly growing fibroblasts and most late-responding (radiation therapy dose-limiting) normal tissues, which have a low proliferation index. © 2011 by Radiation Research Society.


Odrazka K.,Multiscan and Pardubice Regional Hospital | Odrazka K.,Charles University | Odrazka K.,Institute for Postgraduate Medical Education | Dolezel M.,Multiscan and Pardubice Regional Hospital | And 13 more authors.
International Journal of Urology | Year: 2010

Objectives: To retrospectively compare late toxicity of conventional-dose three-dimensional conformal radiation therapy (3D-CRT) and high-dose intensity-modulated radiation therapy (IMRT) for prostate cancer. Methods: A total of 340 patients with T1-3 prostate cancer were treated with 3D-CRT (n = 228) and IMRT (n = 112). The median follow-up time was 5.9 years and 3.0 years, respectively. The prescription dose was 70 Gy for 3D-CRT and 78 Gy for IMRT. Late gastrointestinal (GI) and genitourinary (GU) toxicities were graded according to the Fox Chase modification of the Radiation Therapy Oncology Group and Late Effects Normal Tissue Task Force criteria. Results: There was no difference between 3D-CRT and IMRT in the incidence of GI and GU toxicity at 3 years. On multivariate analysis, transurethral resection of prostate/open transvesical prostatectomy (TURP/TVPE) for benign prostatic hyperplasia, carried out before radiotherapy, significantly increased the risk of Grade ≥2 GU toxicity (risk ratio 1.88). Among patients who experienced TURP/TVPE, the 5-year actuarial likelihood of Grade 2-3 urinary incontinence was 23%, compared with 9% for those without prostate surgery (P = 0.01). Conclusions: Tolerance of 3D-CRT and IMRT was similar, despite the use of high radiation dose with IMRT. Previous TURP/TVPE increased the risk of GU toxicity. © 2010 The Japanese Urological Association.


Sefrova J.,University of Hradec Kralove | Odrazka K.,Multiscan and Pardubice Regional Hospital | Odrazka K.,Charles University | Paluska P.,University of Hradec Kralove | And 10 more authors.
International Journal of Radiation Oncology Biology Physics | Year: 2012

Purpose: To investigate whether the use of magnetic resonance imaging (MRI) in prostate bed treatment planning could influence definition of the clinical target volume (CTV) and organs at risk. Methods and Materials: A total of 21 consecutive patients referred for prostate bed radiotherapy were included in the present retrospective study. The CTV was delineated according to the European Organization for Research and Treatment of Cancer recommendations on computed tomography (CT) and T 1-weighted (T 1w) and T 2-weighted (T 2w) MRI. The CTV magnitude, agreement, and spatial differences were evaluated on the planning CT scan after registration with the MRI scans. Results: The CTV was significantly reduced on the T 1w and T 2w MRI scans (13% and 9%, respectively) compared with the CT scans. The urinary bladder was drawn smaller on the CT scans and the rectum was smaller on the MRI scans. On T 1w MRI, the rectum and urinary bladder were delineated larger than on T 2w MRI. Minimal agreement was observed between the CT and T 2w images. The main spatial differences were measured in the superior and superolateral directions in which the CTV on the MRI scans was 1.8-2.9 mm smaller. In the posterior and inferior border, no difference was seen between the CT and T 1w MRI scans. On the T 2w MRI scans, the CTV was larger in these directions (by 1.3 and 1.7 mm, respectively). Conclusions: The use of MRI in postprostatectomy radiotherapy planning resulted in a reduction of the CTV. The main differences were found in the superior part of the prostate bed. We believe T 2w MRI enables more precise definition of prostate bed CTV than conventional planning CT. © 2012 Elsevier Inc.


Odrazka K.,Multiscan and Pardubice Regional Hospital | Odrazka K.,Charles University | Odrazka K.,Institute for Postgraduate Medical Education | Dolezel M.,Multiscan and Pardubice Regional Hospital | And 13 more authors.
Prostate Cancer and Prostatic Diseases | Year: 2010

Rectum and bladder are the crucial organs at risk for curative radiation therapy of localized prostate cancer. We analyzed the incidence, profile and time course of late rectal radiation toxicity. A total of 320 patients with T1-3 prostate cancer were treated with three-dimensional conformal radiation therapy (3D-CRT). The prescription dose was 70 Gy for T1 and T2 patients (n=230) and 74 Gy for patients with locally advanced T3 tumors (n=90). Late rectal toxicity was graded according to the Fox Chase modification of the Radiation Therapy Oncology Group (RTOG) and Late Effects Normal Tissue Task Force (LENT) criteria. The median follow-up time was 6.2 years (range 0.2-10.7 years). At 5 years, the risk for the development of grade 2 and 3 rectal toxicities was 15.6 and 7.0%, respectively. All new cases of grade 2 and 3 rectal toxicities were observed within 5 years after treatment. Prevalence of grade 2 and 3 rectal symptoms showed fluctuation with maximum at 1.5 years and the minor peak at 4.5 years. Toxicity profile changed significantly over time. The proportion of rectal bleeding within grade 2 and 3 toxicity decreased from 85% at 1.5 years to 46% at 4.5 years. Conversely, the proportion of fecal incontinence among grade 2 and 3 rectal symptoms gradually increased (0% at 1.5 years vs 27% at 4.5 years). Late rectal radiation toxicity represents a dynamic process. Rectal bleeding decreases and fecal incontinence increases over time. © 2010 Nature Publishing Group. All rights reserved.


Dolezel M.,Oncology Center | Dolezel M.,Charles University | Odrazka K.,Oncology Center | Odrazka K.,Charles University | And 9 more authors.
International Journal of Radiation Oncology Biology Physics | Year: 2012

Purpose: Magnetic resonance imaging (MRI)-assisted radiation treatment planning enables enhanced target contouring. The purpose of this study is to analyze the feasibility and accuracy of computed tomography (CT) and MRI data fusion for MRI-based treatment planning in an institution where an MRI scanner is not available in the radiotherapy department. Methods and Materials: The registration inaccuracy of applicators and soft tissue was assessed in 42 applications with CT/MRI data fusion. The absolute positional difference of the center of the applicators was measured in four different planes from the top of the tandem to the cervix. Any inaccuracy of registration of soft tissue in relation to the position of applicators was determined and dose-volume parameters for MRI preplans and for CT/MRI fusion plans with or without target and organs at risk (OAR) adaptation were evaluated. Results: We performed 6,132 measurements in 42 CT/MRI image fusions. Median absolute difference of the center of tandem on CT and MRI was 1.1 mm. Median distance between the center of the right ovoid on CT and MRI was 1.7 and 1.9 mm in the laterolateral and anteroposterior direction, respectively. Corresponding values for the left ovoid were 1.6 and 1.8 mm. Rotation of applicators was 3.1°. Median absolute difference in position of applicators in relation to soft tissue was 1.93, 1.50, 1.05, and 0.84 mm in the respective transverse planes, and 1.17, 1.28, 1.27, and 1.17 mm in selected angular directions. The dosimetric parameters for organs at risk on CT/MRI fusion plans without OAR adaptation were significantly impaired whereas the target coverage was not influenced. Planning without target adaptation led to overdosing of the target volume, especially high-risk clinical target volume - D 90 88.2 vs. 83.1 (p < 0.05). Conclusions: MRI-based preplanning with consecutive CT/MRI data fusion can be safe and feasible, with an acceptable inaccuracy of soft tissue registration. © 2012 Elsevier Inc. All rights reserved.

Discover hidden collaborations