[en] We evaluated coverage, dose homogeneity, dose conformity, and dose gradient in CyberKnife VSI treatment plans. Several dosimetric indices were calculated, and the results were compared with those of previous publications. The effect of target volume on the radiosurgical treatment indices selected was also investigated. The study population comprised the first 40 patients treated at our department from March 2011 to September 2012. Dosimetric indices were calculated and compared with published results for other frame-based and frameless intracranial stereotactic radiotherapy techniques. A comparison of the indices confirmed the ability of the CyberKnife VSI system to provide very high-quality dosing plans. The results were independent of target volume for coverage, homogeneity, and dose conformity. However, a dependence on target volume was observed for the dose-gradient indices analyzed. Based on the indices proposed, CyberKnife provides very good treatment plans and compares favorably with other techniques in most cases. However, greater consensus on the radiosurgery indices calculated would be desirable to facilitate comparison of the various techniques or the same techniques when applied by different users

[en] Purpose: Since reactive oxygen species (ROS) act as mediators of radiation-induced cellular damage, the aim of our studies was to determine the effects of ionizing radiation on the regulation of hepatocellular reduced glutathione (GSH), survival and integrity of nuclear and mitochondrial DNA (mtDNA) in human hepatoblastoma cells (Hep G2) depleted of GSH prior to radiation. Methods and Materials: GSH, oxidized glutathione (GSSG), and generation of ROS were determined in irradiated (50-500 cGy) Hep G2 cells. Clonogenic survival, nuclear DNA fragmentation, and integrity of mtDNA were assessed in cells depleted of GSH prior to radiation. Results: Radiation of Hep G2 cells (50-400 cGy) resulted in a dose-dependent generation of ROS, an effect accompanied by a decrease of reduced GSH, ranging from a 15% decrease for 50 cGy to a 25% decrease for 400 cGy and decreased GSH/GSSG from a ratio of 17 to a ratio of 7 for controls and from 16 to 6 for diethyl maleate (DEM)-treated cells. Depletion of GSH prior to radiation accentuated the increase of ROS by 40-50%. The depletion of GSH by radiation was apparent in different subcellular sites, being particularly significant in mitochondria. Furthermore, depletion of nuclear GSH to 50-60% of initial values prior to irradiation (400 cGy) resulted in DNA fragmentation and apoptosis. Consequently, the survival of Hep G2 to radiation was reduced from 25% of cells not depleted of GSH to 10% of GSH-depleted cells. Fitting the survival rate of cells as a function of GSH using a theoretical model confirmed cellular GSH as a key factor in determining intrinsic sensitivity of Hep G2 cells to radiation. mtDNA displayed an increased susceptibility to the radiation-induced loss of integrity compared to nuclear DNA, an effect that was potentiated by GSH depletion in mitochondria (10-15% intact mtDNA in GSH-depleted cells vs. 25-30% of repleted cells). Conclusion: GSH plays a critical protective role in maintaining nuclear and mtDNA functional integrity, determining the intrinsic radiosensitivity of Hep G2. Although the DNA repair is a complex process that is not yet completely understood, the protective role of GSH probably does not seem to involve the repair of classical DNA damage but may relate to modification of DNA damage dependent signaling

[en] Purpose: The binary multileaf collimator (MLC) is one of the most important components in helical tomotherapy (HT), as it modulates the dose delivered to the patient. However, methods to ensure MLC quality in HT treatments are lacking. The authors obtained data on the performance of the MLC in treatments administered in their department in order to assess possible delivery errors due to the MLC. Correction methods based on their data are proposed. Methods: Twenty sinograms from treatments delivered using both of the authors HT systems were measured and analyzed by recording the fluence collected by the imaging detector. Planned and actual sinograms were compared using distributions of leaf open time (LOT) errors, as well as differences in fluence reconstructed at each of the 51 projections into which the treatment planning system divides each rotation for optimization purposes. They proposed and applied a method based on individual leaf error correction and the increase in projection time to prevent latency effects when LOT is close to projection time. In order to analyze the dosimetric impact of the corrections, inphantom measurements were made for four corrected treatments. Results: The LOTs measured were consistent with those planned. Most of the mean errors in LOT distributions were within 1 ms with standard deviations of over 4 ms. Reconstructed fluences showed good results, with over 90% of points passing the 3% criterion, except in treatments with a short mean LOT, where the percentage of passing points was as low as 66%. Individual leaf errors were as long as 4 ms in some cases. Corrected sinograms improved error distribution, with standard deviations of over 3 ms and increased percentages of points passing 3% in the fluence per angle analysis, especially in treatments with a short mean LOT and those that were more subject to latency effects. The minimum percentage of points within 3% increased to 86%. In-phantom measurements of the corrected treatments showed that, while treatments affected by latency effects were improved, those affected by individual leaf errors were not. Conclusions: Measurement of MLC performance in real treatments provides the authors with a valuable tool for ensuring the quality of HT delivery. The LOTs of MLC are very accurate in most cases. Sources of error were found and correction methods proposed and applied. The corrections decreased the amount of LOT errors. The dosimetric impact of these corrections should be evaluated more thoroughly using 3D dose distribution analysis.

[en] Purpose: The study of acoustic voice parameters (fundamental frequency, jitter, shimmer, and harmonics-to-noise ratio) in extended vowel production, oral reading of a standard paragraph, spontaneous speech and a song in irradiated patients for Tis-T1 vocal cord carcinoma. Methods and Materials: Eighteen male patients irradiated for Tis-T1 vocal cord carcinoma and a control group of 31 nonirradiated subjects of the same age were included in a study of acoustic voice analysis. The control group had been rigorously selected for voice quality and the irradiated group had previous history of smoking in two-thirds of the cases and a vocal cord biopsy. Radiotherapy patients were treated with a 6MV Linac receiving a total dose of 66 Gy, 2 Gy/day, with median treatment areas of 28 cm². Acoustic voice analysis was performed 1 year after radiotherapy, the voice of patients in extended vowel production, oral reading of a standard paragraph, spontaneous speech, and in a song was tape registered and analyzed by a Kay Elemetric's Computerized Speech Lab (model CSL no. 4300). Fundamental frequency, jitter, shimmer, and harmonics-to-noise ratio were obtained in each case. Mann Whitney analysis was used for statistical tests. Results: The irradiated group presented higher values of fundamental frequency, jitter, shimmer, and harmonics-to-noise ratio. Mann-Whitney analysis showed significant differences for fundamental frequency and jitter in vowel production, oral reading, spontaneous speech, and song. Shimmer only showed differences in vowel production and harmonics-to-noise ratio in oral reading and song. Conclusions: In our study only fundamental frequency and jitter showed significant increased values to the control group in all the acoustic situations. Sustained vowel production showed the worst values of the acoustic parameters in comparison with the other acoustic situations. This study seems to suggest that more work should be done in this field

[en] Purpose: To evaluate the results of high-dose-rate brachytherapy (HDRBT) using a schedule of three or four fractions per week, when possible, in 89 patients on local control and toxicity in postoperative treatment of endometrial carcinoma. The effect of the overall HDRBT treatment time (OTT) on toxicity was also evaluated. Patients and Methods: Federation Internationale de Gynecologie Obstetrique Stage: 24 IB, 45 IC, 4 IIA, 6 IIB, 4 IIIA, 2 IIIB, and 4 IIIC. Radiotherapy: Group 1-67 of 89 patients received external beam irradiation (EBI; 44-50 Gy) plus HDRBT (3 fractions of 4-6 Gy); Group 2-22 of 89 patients received HDRBT alone (6 fractions of 4-5 Gy). OTT: Group 1-HDRBT was completed in a median of 5 days in 32 patients and in >5 days in 35; Group 2-HDRBT was completed in <15 days in 11 patients and in ≥16 days in 11. Toxicity was evaluated using Radiation Therapy Oncology Group scores and the bioequivalent dose (BED) study was performed in vaginal mucosa surface. Statistics included Student's t test, chi-square test, and receiving operator curves. Results: With a mean follow-up of 31 months (range, 6-70), 1 of 89 patients had vaginal relapse. Early toxicity appeared in 8 of 89 (9%) patients and was resolved. Late toxicity appeared in 13/89 (14%): vaginal nine Grade 1, three Grade 2, one Grade 4; bladder two Grade 2; rectal three Grade 1, one Grade 2. No differences were found in relation to OTT in Groups 1 and 2. Mean BED was 88.48 Gy in Group 1 and 165.28 Gy in Group 2. Cases with Grade 2 late vaginal toxicity received >75 Gy after EBI and >165 Gy in Group 2. Conclusions: Three fractions of 4-5 Gy in 3-5 days after EBI or 6 fractions in <15 days in patients receiving HDRBT alone was a safe treatment in relation to toxicity and local control. Vaginal surface BED less than 75 Gy after EBI and less than 160 Gy in HDRBT alone may be safe to avoid G2 toxicity.

[en] Purpose: Curative radiotherapy for non-small-cell lung cancer is a difficult challenge, despite the use of conformal radiotherapy. Optimal three-dimensional delineation of treatment volumes is essential for improvement of local control and for limiting of tissue toxicity. Material and Methods: A planning course on clinical practice of lung cancer was held in Barcelona. A questionnaire was given concerning (1) patient positioning, (2) planning-computed tomography scan, (3) accounting for tumor mobility, (4) investigative-procedure respiration-gated radiotherapy and breath-holding maneuvers, (5) generation of target volumes, (6) treatment planning, and (7) treatment delivery. This questionnaire was made to determine the Spanish application of European recommendations. Results: On the negative side, 1 hospital did not use three-dimensional tools, less than 50% used immobilization devices, and 55.6% used computed tomography slices of greater than 5 mm. On the positive side, 70.4% did not use standard margins for gross target volume derived from a computed tomography scan, 92.6% agreed with the inclusion of Naruke anatomic criteria of 1 cm or more in gross target volume planning, and 75% used V20 to estimate the risk of pneumonitis. Conclusions: This study is the first validation of European recommendations for treatment planning and execution of radiotherapy in lung cancer. The main conclusion is the need to improve the negative aspects determined