The effect of patient anatomy on optimised intensity modulated radiotherapy dose distributions for head and neck and prostate cancer

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Radiation doses to normal tissues during craniospinal irradiation: Improvement of the dose to the eye and lens, dosimetric study

Introduction: Craniospinal irradiation is a very important element in treating medulloblastoma. Every effort should be made to decrease the radiotherapy related side effects, especially with the currently available 3D conformal radiotherapy planning system. Objective: This dosimetric study is aiming to report the results of the analysis of doses received by target volumes and organs outside the target volumes during the treatment of medulloblastoma patients. And also by comparing the doses reaching the eyes and the lens with the use of different shielding methods. Methodology: Ten children with recent diagnosis of high risk medulloblastoma were included. They were subjected to MRI of the brain and spine together with CSF cytology 3 weeks after surgery. They were subjected to fixation, conventional simulation, followed by CT simulation. The scans will be transferred to the treatment planning system. The brain, spinal canal, and different normal tissue were outlined.For the cranial fields, parallel opposed fields were used with the isocenter of the fields in the mid-plan in the center of the brain, and behind the eyes. Sensitive tissues close to the target volume were shielded using either MLCS or blocks.The dose prescribed was 36 Gy/20 fractions for cranial and spinal regions. The maximum, minimum, and mean doses to each anatomic structure were computed using dose volume histograms. All patients gave informed consent. Results and conclusion: The dose of radiation received by the target volume and the organs at risk with the use of our new treatment planning system is nearly identical to other studies. The use of block shielding shows lower doses to eyes and lenses regardless of the position of the isocenter, on the other hand, with the use of MLCs for shielding, the isocenter should be behind the eye not in the center of the brain as this shows lower doses to eyes and lenses. Keywords: Craniospinal irradiation, Dose to the eyes and lenses, Dosimetric stud

3DCRT for posterior fossa: Sparing of surrounding organs at risk

Introduction: Radiotherapy of the posterior fossa is routinely delivered using 3DCRT parallel-opposed lateral fields. However high incidence of sensorineural hearing loss, hypothalamic–pituitary dysfunction, thyroid and gonadal dysfunction during radiotherapy makes the need for treatment plan which provides adequate coverage of the target volume while sparing of the cochlea and other surrounding organs at risk (OARs) at same time inevitable. Aim of the work: To compare the coverage of posterior fossa and the dose to surrounding OARs including non-posterior fossa brain, pituitary, cochlea, eyes, optic nerves, optic chiasm, cervical spinal cord, thyroid gland, pharynx, parotid glands and mandible using three different 3DCRT plans. Methods: Ten patients underwent CT simulation for treatment planning of posterior fossa boost. The CT data were transferred to Precise Elekta treatment planning system where posterior fossa, non-posterior fossa brain, pituitary, cochlea, parotid glands, cervical spinal cord, thyroid gland, pharynx, mandible, eyes, lenses, optic nerves and optic chiasm were all contoured. For each patient, three plans were carried out; two parallel opposed open lateral photon fields, a pair of wedged posterior oblique fields, and a pair of wedged posterior oblique fields and an open vertex field. For all plans, the dose distributions and dose volume histogram parameters (DVPs) for the PTV and OARs were compared and analyzed statistically using excel sheet 2003 and SPSS spreadsheet (SPSS base 18). Results: Posterior fossa dose coverage and its homogeneity were adequate and comparable for the three plans. A part from high mean dose received by cochlea, plan 1 shows the best sparing for other OARs. Conclusion: 3DCRT using parallel opposed fields is recommended for posterior fossa irradiation boost as it minimizes the exit dose to all structures other than the cochlea, however its mean dose was within the tolerance

Significant reductions in heart and lung doses using semi lateral decubitus techniques for left sided breast cancer patients: A comparative dosimetric study with supine techniques

Introduction: Various treatment techniques as breath hold techniques have been developed to spare the heart and lung in breast cancer patients receiving adjuvant radiotherapy. Purpose: to compare the heart and lung dosimetric parameters of semi lateral decubitus technique with and without deep inspiration breath hold with standard supine techniques for left-sided breast cancer patients undergoing breast conservative surgery and adjuvant radiotherapy. Methods: Fifty patients with left-sided breast cancer were simulated using standard supine, semi lateral decubitus and semi lateral decubitus and deep inspiration breath hold. The three plans carried out using two tangential opposed photon beams were compared. Results: There was a significant reduction in heart V5Gy, V10Gy, V25Gy, V30Gy, mean dose & max dose with semi-lateral decubitus and breath hold technique compared to supine technique & semi-lateral decubitus technique (P < 0.001). There was also a significant reduction in the above mentioned heart DVPs with semi-lateral decubitus (P < 0.001) compared to supine technique. There was a significant reduction in ipsilateral lung V20Gy and mean dose with semi-lateral decubitus and breath hold technique compared to supine technique (P < 0.001) & semi-lateral decubitus technique (P = 0.003 & 0.006) respectively. There was also a significant reduction in ipsilateral lung V20Gy and mean dose with semi-lateral decubitus (P < 0.001 & 0.007) compared to supine technique. Conclusion: Semi-lateral decubitus techniques with and without breath hold for left sided breast cancer patients significantly reduce the dosimetric parameters of the heart and ipsilateral lung compared to supine technique with comparable target dose coverage

Evaluation of the policy of secondary prevention against rheumatic fever among Egyptian children

Objective: We evaluated the effectiveness of long acting penicillin (LAP) as a 2-weekly regimen in winter and a 3-weekly regimen in summer for prevention of streptococcal colonization and also studied the common complaints of patients during the period of compliance for LAP administration. We also attempted to determine the incidence of relapses or recurrence of rheumatic fever (RF) after the onset of first episode of RF. Patients & methods: 210 rheumatic patients with good compliance to LAP (for at least one year) were included in the study. Demographic, clinical information, patients' complaints and echocardiographic data of rheumatic patients were collected both retrospectively and prospectively. Anti-streptolysin O titre (ASOT) and throat swab culture were done at the end of the study (on Day 14 in the 2-weekly regimen and on Day 21 in the 3-weekly regimen). Results: The age of onset of rheumatic fever was mostly between 5 and 15 years and the youngest patient was 2 years old. Subclinical carditis (SCC) was present in 79 (37%) of all the patients in the study population. Only 7 patients (3.3%) had a relapse within 2 years of the acute episode of RF. At the end of the study, ASOT was found to be high only in 11 patients (5.2%) and throat swab cultures were found negative in all patients Conclusion: LAP regimen is fairly effective in eradicating streptococcal colonization. The incidence of relapse of RF within 2 years of the acute episode of RF is relatively low

Cadmium exposure exerts neurotoxic effects in peacock blennies Salaria pavo

International audienceCadmium (Cd) is considered as an important factor involved in several neurological disturbances. The aim of this study was to assess the effects of Cd in the brain of peacock blennies Salaria pavo, a species used as a bioindicator of water pollution. A sublethal contamination of 2 mg CdCl2 L⁻¹ was performed over periods of 1, 4, 10 and 15 days. Total Cd accumulation was measured in brains and displayed low concentrations throughout the experiment. Partial-length cDNA of different ATP-binding cassette transporters (abcb1, abcc1, abcc2, abcg2 proteins) and acetylcholinesterase (ache) were characterized. mRNA expressions profiles displayed an up-regulation of abcc2 mRNA after 4 days of Cd exposure only while abcg2 mRNA was down-regulated after 10 days only. For AChE, the mRNA transcription and the activity of the enzyme were followed and highlighted that Cd exerted an inhibitory effect on the nervous information transmission. At the histological level, fish exhibited pathological symptoms in the optic tectum and the cerebellum and results showed that the cerebellum was the most affected organ

Effects of Hg sublethal exposure in the brain of peacock blennies Salaria pavo : Molecular, physiological and histopathological analysis

International audienceMarine environments are affected by large amounts of toxicants among those mercury (Hg). The aim of this study was to assess potential neurotoxic effects of Hg in the peacock blenny Salaria pavo. A sublethal contamination to 66 μg HgCl2 L-1 over periods of 1, 4, 10 and 15 days was performed. Total Hg concentrations measured in the brain highlighted the detection of Hg at days 1 and 4 following the exposure but no concentration of the metal was further detected. Partial-length cDNA of genes coding ABC transporters (abcb1, abcc1, abcc2, abcg2) and acetylcholinesterase (ache) were characterized. Results from mRNA expression levels displayed an up-regulation of abcb1 mRNA while a down-regulation of abcc1 and abcc2 mRNA was observed. No change in abcg2 and ache mRNA expression was noted throughout the experiment. At each sampling time, Hg exposure did not affect the activity of the AChE enzyme. The histological analysis indicated that fish exhibited several damages in the optic tectum and the cerebellum and 3 reaction patterns were identified for each organ: circulatory disturbances, regressive and progressive changes. Molecular, physiological and histological biomarkers assessed in the present study highlighted that peacock blennies were able to detoxify Hg from the brain tissue by developing defense mechanisms. More globally, neurotoxic effects of a sublethal Hg exposure in the brain of peacock blennies and the adaptation capacity of this species were evaluated

PENERAPAN MODEL PEMBELAJARAN TEAM ASSISTED INDIVIDUALIZATION (TAI) BERBANTUAN MEDIA POWERPOINT UNTUK MENIGKATKAN HASIL BELAJAR IPS TERPADU PADA SISWA KELAS VIII SMP NEGERI 16 BANDA ACEH

ABSTRAKParasati, Maysila. 2017. Penerapan Model Pembelajaran Team Assisted individualization Berbantuan Media Powerpoint untuk meningkatkan hasil belajar IPS Terpadu pada siswa kelas VIII SMP Negeri 16 Banda Aceh. Skripsi, Jurusan Pendidikan Geografi, Fakultas Keguruan dan Ilmu Pendidikan, Universitas Syiah Kuala. Pembimbing:(1) Drs. Thamrin K, M.Si., (2) Dr. Alamsyah Taher, M.siKata Kunci : Penerapan, Model, Team Assisted Individualization, Hasil Belajar, IPS TerpaduModel pembelajaran Team Assisted Individualization merupakan salah satu model pembelajaran kooperatif yang menuntut para siswa untuk bisa bekerja sama dalam satu kelompok. Penelitian ini bertujuan untuk mengetahui: (1) Peningkatan hasil belajar siswa kelas (2) Kesesuaian aktivitas gurudan siswa (3) Keterampilan guru dalam mengelola pembelajaran (4) Respon siswa terhadap pembelajaran dengan menggunakan model Team Assisted Individualization berbantuan media powerpoint.Pendekatan yang digunakan dalam ppenelitian ini adalah pendekatan kualitatif dalam bentuk penelitian tindakan kelas (Classroom process research). Subjek dalam penelitian ini adalah siswa kelas VIII-4 SMP Negeri 16 banda Aceh yang berjumlah 27 orang siswa. Analisis data menggunakan statistik deskriftif persentase. Hasil penelitian menunjukkan bahwa (1) persentase ketuntasan secara individual meningkat dari 17 siswa yang tuntas pada siklus I, 21 siswa yang tuntas pada siklus II, dan 25 siswa yang tuntas pada siklus III, persentase ketuntasan klasikal juga meningkat dari 50% padasiklus I, 70% pada siklus II, dan 90% pada siklus III; (2) Jumlah kesesuaian aktivitas guru dan siswa meningkat dari 5 aktivitas sesuai pada siklus I menjadi 7 aktivitas sesuai pada siklus II dan 10 aktivitas sesuai pada siklus III; (3) keterampilan guru meningkat dari perolehan skor 2,56 pada siklus I dengan kategori sedang, skor 3,2 pada siklus II dengan kategori baik,dan skor 3,36 pada siklus III dengan kategori baik; (4) sebanyak 100% siswa menyatakan bahwa model pembelajaran Team Assited Individualization adalah baru membantu siswa dalam memahami materi pelajaran.Berdasarkan hasil penelitian ini dapat disimpulkan bahwa, terdapat peningkatan prestasi belajar siswa mulai dari siklus I sapai siklus III dengan menggunakan model Team Assisted Individualization berbantuan media powerpoint di kelas VIII-4 SMP Negeri 16 Banda Aceh.Banda Ace