Dosimetric comparison between treatment plans of patients treated with low-dose-rate vs. high-dose-rate interstitial prostate brachytherapy as monotherapy: Initial findings of a randomized clinical trial.

PURPOSE: The aim of this study was to compare the dosimetry of intraoperative dose plans of prostate cancer patients treated with low-dose-rate (LDR) and high-dose-rate (HDR) interstitial brachytherapy (BT). METHODS AND MATERIALS: A randomized clinical trial was initiated at our institution to compare the results and side effects of LDR and HDR BT as monotherapy in the treatment of early, organ-confined prostate cancer patients. Eighty-seven patients were randomly assigned to receive HDR afterloading BT with one fraction of 19 Gy or permanent LDR 125I seed BT with 145 Gy. Inverse optimization algorithms were used for planning. Stranded seeds were implanted using live ultrasound imaging after preimplant treatment planning. Final dosimetry of HDR treatments was based on updated needle and contour positions. Statistical comparisons with nonparametric test were performed between the corresponding dose-volume parameters. RESULTS: The V100 and V150 were 99% and 61%, respectively, for LDR, whereas 98% and 32% for HDR treatments. The D90 was less for HDR (122% vs. 110%). The dose distributions were more homogeneous and conformal with HDR technique (dose homogeneity index, 0.39 vs. 0.67; conformal index, 0.65 vs. 0.80). The urethra and rectum received significantly less dose with HDR. The D10 and D30 for urethra were 133% and 128%, respectively, for LDR and 114% and 111% for HDR treatments. The [Formula: see text] for rectum was 68% and 55% for LDR and HDR technique, respectively. CONCLUSIONS: Both techniques provided acceptable target volume coverage with a slightly higher value with the LDR technique. The dose distributions were more homogeneous and conformal, and both urethra and rectum were better protected with the HDR technique.

A Retrospective Analysis of the First 41 mCRPC Patients with Bone Pain Treated with Radium-223 at the National Institute of Oncology in Hungary.

Radium-223 dichloride is an alpha-emitting radiopharmaceutical which significantly prolongs overall survival in patients with castration-resistant prostate cancer (CRPC) and symptomatic bone metastases. This was a retrospective analysis of the efficacy and safety of Radium-223 in the first 41 patients treated at a single center in Hungary. Radium-223 was given at a dose of 50 kBq/kg intravenously every 4 weeks for up to 6 cycles. Between 23rd July 2014 and 23rd February 2016, 41 patients were treated. Patient demographics, laboratory values, treatment outcomes and adverse events were collected from medical records. The mean age was 72.2 years (SD: 7.1). 24 patients received Radium-223 as first-line treatment (58%), 7 patients as second (17%), 3 as third (7.3%), 6 as (14.6%), and 1 as fifth-line therapy (2.4%). The mean number of cycles administered was 5.5 (SD: 1.1). The most common side effects were anemia (32% grade 1-3), nausea (28%, grade 1), diarrhea (4%, grade 2), thrombocytopenia (4%, grade 3). The mean baseline PSA level was 307.2 ng/ml (SD: 525.7), which increased to a mean value of 728.5 ng/ml (SD: 1277) by the end of treatment. The baseline mean ALP of 521.1 U/L (SD: 728) decreased to 245.1 U/L (SD: 283.5). The majority of patients experienced a decrease (37%) or complete cessation (43%) of bone pain intensity. In our symptomatic prostate cancer patient population, Radium-223 proved to be efficient in terms of pain relief, with moderate side effects. No PSA response was detected, while alkaline phosphatase levels significantly decreased.

Patient positioning variations to reduce dose to normal tissues during 3D conformal radiotherapy for high-risk prostate cancer.

BACKGROUND AND PURPOSE: The goal of this work was to assess optimal treatment positioning of 3D conformal radiotherapy (3DCRT) for high-risk prostate cancer patients. PATIENTS AND METHODS: Treatment plans of 25 patients in different patient positions were evaluated: with knee and ankle support (KAS) in the supine position and with a belly board (BB) in the prone position both with full (FB) and empty bladder (EB). Planning target volumes (PTVs) for pelvis, prostate and vesicles, prostate, and organs at risk (OARs) were delineated. Dose and overlapping volumes were evaluated. RESULTS: Overlapping volumes were significantly smaller with a FB than with an EB. No significant differences were found in overlapping volumes with respect to patient fixation systems, but the percentage values of dose to the OARs showed significantly better results employing KAS than a BB. A FB reduced the dose volumes to the OARs. Comparison with respect to circumference of abdomen (CA) showed significantly smaller overlapping at large CA in most of the cases. CONCLUSION: Supine position is suggested with KAS combined with a FB (especially in cases of larger CA) when using 3DCRT with planning technique modification for high-risk prostate cancer patients to reduce the dose of OARs, based on our results.

CT densitometry of the brain: a novel method for early detection and assessment of irradiation induced brain edema.

The purpose of the study was to examine if the CT densitometric analysis during radiotherapy (RT) of brain tumors is suitable for the early detection of RT induced brain edema (BE), predicting related neurological progress, and assessing the effects of different edema therapies. Planimetric CT-densitograms were constructed by modifying the "High-Lighting" method. Three theoretical density regions were defined and color-coded on the images of the brain. These were defined as edema (10-20 HU), mild edema, and normal brain (29-38 HU). Corresponding axial CT slices were created at the mid-level of the lesion and that of the periventricular white matter to verify the changes in perifocal and diffuse BE. The monitoring was performed on 50 solitary brain tumor patients treated with RT. During RT courses weekly CT-densitometric examinations were carried out. We experienced that changes in densitograms coincided with clinical symptoms, furthermore, preceded the latter. With the use of preventive edema medication based on diuretics and along with adjunctive edema medication adopted to densitograms, the 5-7 week irradiation was completed without ultimate worsening in performance state in 49 of 50 cases and besides we succeeded in avoiding the routine usage of steroids. Based on our findings the CT-densitometry is suitable for early detection and continuous assessment of BE and preventing patient distress during RT. This simple, reproducible and non-invasive procedure could provide an additional clinical tool for new treatment strategies.

A PET study on the characterization of partially reversible radiogenic lower motor neurone disease.

OBJECTIVE: To investigate the pathomechanism of the rare radiogenic lower motor neurone disease (LMND) on the basis of a case history involving a partial functional recovery. PATIENT: A 31-year-old seminoma patient received postoperative para-aortic and para-iliac telecobalt irradiation with a biologically effective dose of 88 Gy(2) (44 Gy in 2 Gy fractions/day, with an estimated alpha/beta of 2 Gy) delivered to the spinal cord following a single cycle of chemotherapy. LMND developed 4 months after the completion of radiotherapy. The patient exhibited flaccid paraparesis of the lower extremities (without sensory or vegetative signs), followed by a worsening after further chemotherapy, due to pulmonary metastatization. A gradual spontaneous functional improvement commenced and led several years later to a stabilized state involving moderately severe symptoms. METHODS: In the 15th year of the clinical course, magnetic resonance imaging (MRI) and positron emission tomography (PET) with [(18)F]fluorodeoxyglucose (FDG) and [(11)C] methionine were conducted. Four lines of experiments (clonogenic assay using fibroblasts isolated from a skin biopsy sample of the patient, comet assay, micronucleus assay, and the testing of chromosome aberrations after in vitro irradiation of peripheral blood samples) were performed in a search for an increased individual radiosensitivity. RESULTS: MRI investigations failed to reveal any pathological change. PET demonstrated an increased FDG accumulation, but a negligible [(11)C] methionine uptake in the irradiated spinal cord segments. The radiobiological investigations did not indicate any sign of an increased individual radiosensitivity. CONCLUSIONS: We suggest that the observed partial functional recovery and stabilization of the symptoms of radiogenic LMND may be explained by the higher than normal density of sodium channels expressed along the demyelinated axons of the restored conduction. The increased energy demands of this type of conduction are proved by a higher metabolic rate (increased FDG uptake) of the irradiated spinal cord segments without a substantial regenerative process (lack of detectable protein synthesis).