Relative output factor measurements of a 5 mm diameter radiosurgical photon beam using polymer gel dosimetry

Besides the fine spatial resolution inherent in polymer gel-magnetic resonance imaging (MRI) dosimetry, the method also features the potential for multiple measurements of varying sensitive volume in a single experiment by integrating results in MRI voxels of finite dimensions (i.e., in plane resolution by slice thickness). This work exploits this feature of polymer gel dosimetry to propose an experimental technique for relative output factor (OF) measurements of small radiosurgical beams. Two gel vials were irradiated with a 5 and 30 mm diameter 6 MV radiosurgery beam and MR scanned with the same slice thickness and three different in plane resolutions. Using this experimental data set, 5 mm OF measurements with the PinPoint ion chamber are simulated by integrating results over a sensitive volume equal to that of the chamber. Results are found in agreement within experimental uncertainties with actual PinPoint measurements verifying the validity of the proposed experimental procedure. The polymer gel data set is subsequently utilized for OF measurements of the 5 mm beam with varying sensitive volume to discuss the magnitude of detector volume averaging effects. Seeking to correct for volume averaging, results are extrapolated to zero sensitive volume yielding a 5 mm OF measurement of (0.66+/-5%). This result compares reasonably with corresponding ionometric and radiographic film measurements of this work and corresponding, limited, data in the literature. Overall, results suggest that polymer gel dosimetry coupled with the proposed experimental procedure helps overcome not only tissue-equivalence and beam perturbation implications but also volume averaging and positioning uncertainties which constitute the main drawback in small radiosurgical beam dosimetry.     

Fetal Electrocardiogram Extraction and Analysis Using Adaptive Noise Cancellation and Wavelet Transformation Techniques

Birth defect-related demise is mainly due to congenital heart defects. In the earlier stage of pregnancy, fetus problem can be identified by finding information about the fetus to avoid stillbirths. The gold standard used to monitor the health status of the fetus is by Cardiotachography(CTG), cannot be used for long durations and continuous monitoring. There is a need for continuous and long duration monitoring of fetal ECG signals to study the progressive health status of the fetus using portable devices. The non-invasive method of electrocardiogram recording is one of the best method used to diagnose fetal cardiac problem rather than the invasive methods.The monitoring of the fECG requires development of a miniaturized hardware and a efficient signal processing algorithms to extract the fECG embedded in the mother ECG. The paper discusses a prototype hardware developed to monitor and record the raw mother ECG signal containing the fECG and a signal processing algorithm to extract the fetal Electro Cardiogram signal. We have proposed two methods of signal processing, first is based on the Least Mean Square (LMS) Adaptive Noise Cancellation technique and the other method is based on the Wavelet Transformation technique. A prototype hardware was designed and developed to acquire the raw ECG signal containing the mother and fetal ECG and the signal processing techniques were used to eliminate the noises and extract the fetal ECG and the fetal Heart Rate Variability was studied. Both the methods were evaluated with the signal acquired from a fetal ECG simulator, from the Physionet database and that acquired from the subject. Both the methods are evaluated by finding heart rate and its variability, amplitude spectrum and mean value of extracted fetal ECG. Also the accuracy, sensitivity and positive predictive value are also determined for fetal QRS detection technique. In this paper adaptive filtering technique uses Sign-sign LMS algorithm and wavelet techniques with Daubechies wavelet, employed along with de noising techniques for the extraction of fetal Electrocardiogram.Both the methods are having good sensitivity and accuracy. In adaptive method the sensitivity is 96.83, accuracy 89.87, wavelet sensitivity is 95.97 and accuracy is 88.5. Additionally, time domain parameters from the plot of heart rate variability of mother and fetus are analyzed.     

Three dimensional printed electron beam modifier for total skin electron treatments

Total Skin Electron Beam (TSEB) treatment, despite its proven effectiveness in skin malignancies, is a rather exhausting irradiation method, especially for feeble patients. In an effort to reduce treatment time by creating a clinically acceptable single TSEB field, various beam modifiers of different materials and shapes were tested. Using the TSEB immobilization device of our department and 3D printing technology, aluminum and thermoplastic modifiers were designed and constructed, according to the resulting profiles at treatment distance. Electron beam characteristics were measured and calculated both at SSD = 100 cm and at treatment level. Aluminum scatterers of the same thickness caused different modification according to the area of blocking. Aluminum modifiers reduced significantly central dose deposition for the same amount of MUs and therefore they expanded treatment time in undesirable levels. Plastic modifiers offer a good combination of field dimensions and treatment time. The final 3D printed modifier shaped the electron beam as desired resulting to a clinically acceptable 6 MeV field of 176 × 70 cm field with 10% inhomogeneity in vertical and 3% in the lateral dimension with adequate skin coverage at SSD = 400 cm. This modification offered approximately a two-minute treatment time reduction compared to the current technique. Underdosed areas appear near the edge of the field, but in regions that are far from the torso of the patient. Bremsstrahlung radiation was kept at clinically accepted levels (< 5%). This modification of the original six dual-field technique of our hospital could probably benefit fragile patients who could not easily tolerate a twenty-minute standing position without compromising the quality of their treatment.     

Acute severe asthma

Acute exacerbations of asthma are very common reasons for a presentation to emergency departments. This paper focuses on defining the high‐risk group, consideration of the concept of phenotypes of acute asthma, the assessment of severe and life‐threatening exacerbations and an emphasis on the management of the more severe end of the exacerbation severity. A number of evidence‐based guidelines exist throughout the world and are all slightly different. This reflects the poor evidence base for some of those recommendations. Thus, a large variation of treatment drugs, doses and regimen are used and clearly not standardised. This paper aims to present a summary of the best evidence and discuss some of these controversies. The most important aspect of treating an exacerbation of acute asthma is to review regularly and assess response to treatment. Severe and life‐threatening episodes should be treated with early use of intravenous treatment in a stepwise manner following the local guidelines. Non‐invasive ventilation and high flow nasal cannulae delivery of oxygen in the emergency department are evolving modalities, but evidence for their use is currently limited.     

Intraoperative hyperthermia and chemoradiotherapy for inoperable pancreatic carcinoma

The aim of this study was to evaluate the tolerability and the possible clinical benefit of intraoperative hyperthermia combined with multischedule chemotherapy and bypass surgery for the palliative treatment of inoperable pancreatic cancer. Ten patients with unresectable adenocarcinoma of the pancreas received preoperative chemotherapy [5-fluorouracil (5-FU)], bypass surgery and postoperative chemotherapy (5-FU, doxorubicin and cisplatin) plus sandostatin and radiotherapy (45 Gy, 25 fractions, 5 days a week). A single session of intraoperative hyperthermia was performed, by using a waveguide-type applicator (433 MHz). The tumour region was heated to 43-45 degrees C for up to 60 min, while 500 mg 5-FU was infused simultaneously through the gastroduodenal into the splenic artery. Postoperative recovery was uneventful for all patients. A brief instrument was developed for evaluating patients' quality of life. Chemotherapy-related toxicity included myelosuppression, vomiting, alopecia and increase in blood urea nitrogen (BUN), creatinine, SGOT and SGPT. Glucose and amylase determinations remained within normal limits throughout the whole treatment. There was a significant improvement before and 1 month after combined treatment in Eastern Cooperative Oncology Group (ECOG) status (1.8 +/- 0.4), Scott-Huskinsson pain scale (3.2 +/- 0.8) and quality of life score (30.5 +/- 6.7). No progressive disease was noticed and the median overall survival was 11 (SE = 2.4) months. There was also a significant (P = 0.002, Wilcoxon test) decrease in values of both serum carcinoembryonic antigen (CEA) and carbohydrate antigen (CA19-9), from 7.6 +/- 1.3 ng/mL and 875.7 +/- 104.8 U/mL to 3.5 +/- 0.7 ng/mL and 65.3 +/- 14.1 U/mL respectively. The first clinical results suggest a potential advantage of using combined intraoperative hyperthermia, chemotherapy and postoperative radiotherapy in the palliative treatment of the adenocarcinoma of the pancreas. The whole procedure seems to be free of perioperative morbidity, while the chemotherapy toxicity was rather moderate. However, the preliminary nature limits the general applicability of our results.     

Cytoprotective effect of amifostine in radiation-induced acute mucositis - a retrospective analysis

PURPOSE: To study the cytoprotective impact of amifostine against acute radiation mucositis. PATIENTS AND METHODS: A total of 117 cancer patients with carcinomas localized in pelvic organs, lung and head and neck were entered into this study. In a retrospective way, and in order to minimize the bias related to the investigator, 138 patients as historical controls were randomly selected from a database in our hospital. Acute radiation-induced gastrointestinal mucositis, esophagitis and stomatitis were assessed using the common toxicity criteria scale. The most severe grade recorded was evaluated as the final morbidity score for this patient. Mean toxicity score (MTS) was the mean value of recorded acute radiation toxicity. Mean interruption time (MIT) was the mean value of recorded interruption time due to radiation toxicity. RESULTS: A significantly reduced severity of symptomatology related to oral, esophageal and rectal mucosa was noted in the amifostine group (group A) (p < 0.05, chi-square test). Furthermore, a significant reduction of MTS as well as MIT was observed in group A versus the historical controls (group B) (p < 0.05, Mann-Whitney U test). CONCLUSION: The administration of amifostine seems to protect patients against radiation-induced mucositis, but further investigation with randomized trials is needed.     

The cytoprotective effect of amifostine in acute radiation dermatitis: a retrospective analysis

To study the impact of amifostine as a cytoprotective agent against acute radiation dermatitis, we reviewed 220 patient records. One hundred cancer patients, with tumors localised in the pelvis (bladder, rectum, prostatic carcinomas, or gynecological cancer), who received radiotherapy and cytoprotective treatment with intravenous infusion of amifostine (group A) were included in this study. Retrospectively, we randomly selected from a database in our hospital 120 historical controls, who received only radiotherapy without cytoprotection (group B). Mean gross dermatitis score (MGDS) was the mean value of recorded acute radiation dermatitis according to common toxicity criteria. In group A versus B patients, a significantly reduced severity of dermatitis (P < 0.001, Fisher's exact test) and significant reduction of MGDS as well as mean interruption treatment time (P < 0.001, Mann-Whitney U test) was observed. The relative risk of the outcome of the two study groups was 0.23 (95% CI: 0.15 to 0.34). The significant dermato-cytoprotective effect of amifostine noticed in our retrospective analysis warrants further investigation with randomised trials.     

Alloimmunization Against Well Defined Polymorphic Major Histocompatibility or Class I MHC Transfected L Cells Antigens Can Prevent Poly IC Induced Fetal Death in Mice

METHOD : It is possible to induce increased fetal resorption in a number of inbred murine matings by injecting Poly (I) Poly (C12U) 3.5 days postconception, a maneuver associated with natural killer-mediated damage to the feto placental unit such as occurs in spontaneous fetal resorptions. RESULTS : We show here that alloimmunization can block this effect. In addition, maternal immune responses induced by alloimmunization against isolated mutant class I or class II, as well as by immunization with class I MHC alloantigens (K^d) transfected L cells are sufficient to restore normal fetal viability. It is not necessary that the maternal immune response be specifically directed against paternal alloantigens fr the fetal protecton to ensue, since the effect occurs in inbred matings when the mother is immunized against unrelated class I or class II alloantigens. As in previous studies conducted in the murine species, not all MHC alloimmunizations are protective. In addition, as control, immunization with a monomorphic class I MHC molecular (37), transfected L cells, sheep red blood cells or hen egg lysozyme is without effect. CONCLUSION : These results indicate that defined MHC antigens can mediate fetal protection from induced fetal resorption, and suggest that one driving force in promoting MHC antigen polymorphism in mammals is their capacity to confer protection from NK mediated fetal demise.