حكـم استحـداث الضرائـب المعاصـرة (ضريبة القيمة المضافة أنموذجا) The Ruling of Creating Contemporary Taxes (Value Added Tax as a Model)

ملخص تهدف هذه الدراسة إلى الوصول إلى الحكم الفقهي في استحداث ضرائب جديدة، وقد ركز البحث على نموذج منها هو ضريبة القيمة المضافة، وذلك في ضوء الآثار الاقتصادية، والاجتماعية التي تنجم عن تطبيقها، ومدى انسجامها مع المقاصد الشرعية، التي تهدف إلى تحقيق العدل، والإحسان، ورفع الحرج. وللوصول إلى هذا الهدف، تبدأ الدراسة بالتعريف بالضرائب بشكل عام، ومن ثم ضريبة القيمة المضافة: (وهي ضريبة غير مباشرة تفرض على بيع السلع، أو استيراد كل السلع والخدمات إلا ما استثني بنص قانوني ، وذلك في كل مرحلة من مراحل التداول، ويتحملها المستهلك النهائي)، ثم بيان خصائصها، وآثارها، يلي ذلك عرض آراء الفقهاء حول هذه الضريبة، وأدلتهم، والرأي الراجح. وتخلص الدراسة إلى أن الإسلام يقدم درء المفاسد على جلب المصالح، ومن ثم فإن دفع الضرر والضيق والحرج عن الفقراء ومحدودي الدخل، مقدم على جلب المصالح، وبناء على ذلك: فقد ترجح لدى الباحث منع هذه الضريبة، وأنه في حال استجد ما يستدعي فرض تكليف مالي زائد؛ فإن الأولى التدرج في اختيار أنواع الضرائب، فتقدم مثلا ضريبة الدخل عليها؛ لاعتبارات كثيرة، كقربها من العدالة. الكلمات الافتتاحية: ضرائب – معاصرة - القيمة المضافة. The Ruling of Creating Contemporary Taxes (Value Added Tax as a Model) Abstract This study aims to reach the Islamic jurisprudential ruling of creating new taxes, and the research has focused on a model of Value Added Tax “VAT”, considering the economic and social effects that result from its application, and the extent of its compatibility with the Islamic Lawful purposes which aim to achieve justice, and charity and mitigate difficulties. In order to reach this goal, the study begins with the definition of taxes in general, then VAT: (which is an indirect tax imposed on the sale of goods, or the import of all goods and services except for what is excluded by a legal text , at each stage of trading, and it is borne by the final consumer), then clarifying its characteristics and effects, followed by stating the opinions of Islamic jurists about this tax, their evidence, and the most preponderant opinion. The study concludes that Islam gives priority for warding off mischiefs over bringing benefits, therefore preventing harm, distress and difficulties from the poor and low-income persons is better than bringing benefits. Accordingly: the researcher thinks the most preponderant opinion is to prevent this tax, and in the event there is a need to impose an excessive financial charge; it is more adequate to graduate in choosing the types of taxes, for example, the income tax shall take precedence over VAT; for may considerations, such as its proximity to justice. Keywords: Taxes - Contemporary - Value Added

The Spectral Measurement of Scattered Radiation From a Clinical Linear Accelerator Using a CZT Detector

The study of the induced radioactivity following radiotherapy with high energy X-rays from medical linear accelerator. Patient equivalent phantom made of Polymethyl methacrylate (PMMA) of 30x30x27 cm size irradiated with 15 MV X-rays from Versa HD medical linear accelerator form Elekta. Induced radioactive and ambient dose rates were measured at 0.25, 0.5 and 1 m from beam center using GR1® spectrometry with Cadmium Zinc Telluride (CZT) detectors having energy resolution less than 2%. Spectrum analysis was performed using MultiSpect software. The measured spectrum showed 511 keV annihilation photons possibly as a result of positron emitter of which most likely candidates are 62Cu(T1/2: 9.7 min), 64Cu (T1/2: 12.7 h )  and 57Ni  (T1/2:  35.6 h) and a  peak at ≈ 1780 keV that could be attributed 28Al and 214Bi radioisotope. Ambient photon dose rates post radiotherapy treatment ranged 660 µGyh-1at o.5 m to 41 µGyh-1at 1 m. These values agree well with the results presented in the literature. Keywords: Radiotherapy; Activation Products; Gamma spectrometry; Occupational exposure; Medical Linear Accelerator. DOI: 10.7176/ALST/83-05 Publication date: November 30th 2020

Determination of staff doses in mobile and static PET/CT units and the influence of design and shielding.

Positron Emission Tomography (PET) is considered as the fastest expanding diagnostic imaging system in the world, and has become one of the major tools in diagnosis and staging in oncology. Although all the European countries together do not have yet as many scanners as the USA, they have almost completed Phase One of the PET/Computer Tomography (CT) Services Plan. For example, the number of PET/CT scanners in England has increased by a factor of three during the last three years and the focus is now on the advanced PET/CT system. Combined PET and CT scanning is an advanced imaging modality that offers high patient throughput, but results in increased occupational radiation dose exposure. In addition, mobile PET/CT systems have been used to overcome space and money limitations. However, the working environment in a mobile scanner unit places particular constraints on space, patient handling and workflow. These factors stimulated us to investigate the occupational radiation exposure doses for a number of static and mobile PET and PET/CT services provided by NHS hospitals and private companies. The vital goal of this work was to determine staff doses in both static and mobile PET/CT environments and examine the influence of shielding and design by Monte-Carlo simulation. The PET/CT workflow for staff was divided into six phases that were given operational definitions, and start and end points. Using stopwatches, dose rate meters, electronic personal dosimeters (EPDs) made by Thermo and portable LaBr3 spectrometers and dosimeters made by Canberra, exposure time, dose rate, gamma ray spectrum and dose measurements were performed over a period of time varying between 1 day and 5 weeks by various technologists working in 3 static and 3 mobile PET/CT units. Measurements of exposure rate from more than 1250 patient procedures in total were collected and analysed. Experimental studies concluded that the occupational back ground was quite high (>3 muSv/8hours) in some locations and that injected patients were released with high dose rates exceeding 60 muSv/h in the close contact position (< 40 cm). In addition, in designs where the hot-lab room was located between the reception desk and control room without proper shielding, the exposure dose rate in the air exceeded 15 muSv/h at 120 cm from the wall of the hot-lab. The use of a portable LaBr3 detector was important because it has an excellent energy and timing resolution, superior intrinsic spatial resolution and high detection efficiency. Existing occupational doses recorded previously were analysed and provided information that was used in the experimental design of more detailed measurements. Although these results indicated that occupational background is very high in most units, all staff members currently working in Medical PET and PET/CT units are within the regulatory limits for non-classified occupational exposure (<6 mSv per year). However, many of the staff would exceed the classification level if the occupational background was not subtracted. The average exposure time for staff working in static and mobile environments was around 15 minutes and 25 minutes per patient respectively for all 6 defined workflow phases. The corresponding average exposure dose was 5.0 muSv (static) and 5.7 muSv (mobile) per patient. High exposure times and doses were seen to occur during the injection phase and the scanning phase, where staff members are in prolonged close contact with radioactive patients. In addition, on the mobile PET/CT unit, accompanying the patient to the toilet prior to the scan also incurred a high dose, in particular when patients needed additional assistance. It was found that at least 10% of the total dose was not attributable to any of the defined tasks in the workflow, and instead was attributed to unexpected occupational exposure as well as carelessness. Monte Carlo simulation was used to check the dose map inside the unit and to certify the shielding calculation and design. Also, the simulation was used to compare the staff effective dose per patient. Two types of tallies were used as a cross check and showed excellent agreement. Based on the findings of the experimental and numerical studies, a number of strategies for reducing occupational exposures in all workflow phases are suggested

Determination of staff doses in mobile and static PET/CT units and the influence of design and shielding

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study

Background: Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. Methods: The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18-49, 50-69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. Results: NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351; best case 196, worst case 816) or non-cancer surgery (733; best case 407, worst case 1664). Both exceeded the NNV in the general population (1840; best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year. Conclusion: As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population