Serum Malondialdehyde and Urinary Neopterin Levels in Glass Sandblasters Exposed to Crystalline Silica Aerosols

The aim of this cross-sectional study was to explore the association of crystalline silica aerosols exposure with malondialdehyde in blood serum and urinary neopterin and explore their potential as biomarkers of their external exposure. Nonsmoking and healthy male glass sandblasters and control population were randomly selected for this study. All groups were monitored for their personal exposure to crystalline silica according to NOISH method No. 7601. High Performance Liquid Chromatography (HPLC) was used to for analysis of malondialdehyde of blood serum and urinary neopterin, and creatinine in all study participants. The mean of personal exposure to crystalline silica aerosols in glass sanbalsters was 164 µg/m3 (SD: 112) compared with less than 0.006 mg/m3 for control group that was even below detection limit. The mean of blood serum malondialdehyde of sandblasters (49.08±19.05µmole/l) was significantly higher than that of control population 1.92±0.33 µmole/l (p<0.001). Urinary neopterin of sandblasters was 10.85±3.61 mmole/mole creatinine which was also significantly higher than control group 4.71±1.88 mmole/mole creatinine (p<0.001). Correlation between occupational exposures of glass sandblasters to crystalline silica with blood serum malondialdehyde was significant (r2=0.279, p<0.01). Malondialdehyde of blood serum and urinary neopterin could be regarded as biomarkers of exposure to crystalline silica aerosols

Clinical implementation of electron energy changes of Varian linear accelerators

Modern dual photon energy linear accelerators often come with a few megavoltage electron beams. The megavoltage electron beam has limited range and relative sharp distal falloff in its depth dose curve compared to that of megavoltage photon beam. Its radiation dose is often delivered appositionally to cover the target volume to its distal 90 % depth dose (d90), while avoiding the normal- sometimes critical-structure immediately distal to the target. Varian linear accelerators currently offer selected electron beams of 4, 6, 9, 12, 16 and 20 MeV electron beam energies. However, intermediate electron energy is often needed for optimal dose distribution. In this study we investigated electron beam characteristics and implemented two intermediate 7 and 11 MeV electron beams on Varian linear accelerators. Comprehensive tests and measurements indicated the new electron beams met all dosimetry parameter criteria and operational safety standards. Between the two new electron beams and the existing electron beams we were able to provide a choice of electron beams of 4, 6, 7, 9, 11, 12, 16 and 20 MeV electron energies, which had d90 depth between 1.5 cm and 6.0 cm (from 1.5 cm to 4.0 cm in 0.5 cm increments) to meet our clinical needs. PACS number: 87.56.bd. Key words: llinear accelerator, electron beam energy chang

Hematologic Toxicity in RTOG 0418: A Phase 2 Study of Postoperative IMRT for Gynecologic Cancer

Intensity modulated radiation therapy (IMRT), compared with conventional 4-field treatment, can reduce the volume of bone marrow irradiated. Pelvic bone marrow sparing has produced a clinically significant reduction in hematologic toxicity (HT). This analysis investigated HT in Radiation Therapy Oncology Group (RTOG) 0418, a prospective study to test the feasibility of delivering postoperative IMRT for cervical and endometrial cancer in a multiinstitutional setting. Patients in the RTOG 0418 study were treated with postoperative IMRT to 50.4 Gy to the pelvic lymphatics and vagina. Endometrial cancer patients received IMRT alone, whereas patients with cervical cancer received IMRT and weekly cisplatin (40 mg/m2). Pelvic bone marrow was defined within the treatment field by using a computed tomography density-based autocontouring algorithm. The volume of bone marrow receiving 10, 20, 30, and 40 Gy and the median dose to bone marrow were correlated with HT, graded by Common Terminology Criteria for Adverse Events, version 3.0, criteria. Eighty-three patients were eligible for analysis (43 with endometrial cancer and 40 with cervical cancer). Patients with cervical cancer treated with weekly cisplatin and pelvic IMRT had grades 1-5 HT (23%, 33%, 25%, 0%, and 0% of patients, respectively). Among patients with cervical cancer, 83% received 5 or more cycles of cisplatin, and 90% received at least 4 cycles of cisplatin. The median percentage volume of bone marrow receiving 10, 20, 30, and 40 Gy in all 83 patients, respectively, was 96%, 84%, 61%, and 37%. Among cervical cancer patients with a V40 >37%, 75% had grade 2 or higher HT compared with 40% of patients with a V40 less than or equal to 37% (P =.025). Cervical cancer patients with a median bone marrow dose of >34.2 Gy also had higher rates of grade ≥2 HT than did those with a dose of ≤34.2 Gy (74% vs 43%, P=.049). Pelvic IMRT with weekly cisplatin is associated with low rates of HT and high rates of weekly cisplatin use. The volume of bone marrow receiving 40 Gy and the median dose to bone marrow correlated with higher rates of grade ≥2 toxicity among patients receiving weekly cisplatin (cervical cancer patients). Evaluation and limitation of the volume of bone marrow treated with pelvic IMRT is warranted in patients receiving concurrent chemotherapy

Lung tumor segmentation methods: Impact on the uncertainty of radiomics features for non-small cell lung cancer.

PURPOSE:To evaluate the uncertainty of radiomics features from contrast-enhanced breath-hold helical CT scans of non-small cell lung cancer for both manual and semi-automatic segmentation due to intra-observer, inter-observer, and inter-software reliability. METHODS:Three radiation oncologists manually delineated lung tumors twice from 10 CT scans using two software tools (3D-Slicer and MIM Maestro). Additionally, three observers without formal clinical training were instructed to use two semi-automatic segmentation tools, Lesion Sizing Toolkit (LSTK) and GrowCut, to delineate the same tumor volumes. The accuracy of the semi-automatic contours was assessed by comparison with physician manual contours using Dice similarity coefficients and Hausdorff distances. Eighty-three radiomics features were calculated for each delineated tumor contour. Informative features were identified based on their dynamic range and correlation to other features. Feature reliability was then evaluated using intra-class correlation coefficients (ICC). Feature range was used to evaluate the uncertainty of the segmentation methods. RESULTS:From the initial set of 83 features, 40 radiomics features were found to be informative, and these 40 features were used in the subsequent analyses. For both intra-observer and inter-observer reliability, LSTK had higher reliability than GrowCut and the two manual segmentation tools. All observers achieved consistently high ICC values when using LSTK, but the ICC value varied greatly for each observer when using GrowCut and the manual segmentation tools. For inter-software reliability, features were not reproducible across the software tools for either manual or semi-automatic segmentation methods. Additionally, no feature category was found to be more reproducible than another feature category. Feature ranges of LSTK contours were smaller than those of manual contours for all features. CONCLUSION:Radiomics features extracted from LSTK contours were highly reliable across and among observers. With semi-automatic segmentation tools, observers without formal clinical training were comparable to physicians in evaluating tumor segmentation