Evaluation of the relative TL efficiency of the thermoluminescent detectors to heavy charged particles

The relative thermoluminescence efficiency, amp; 951;, is in general not constant but depends on ionisation density. Evaluation of the amp; 951; is therefore important especially for correct interpretation of measurements of densely ionising radiation doses in proton radiotherapy or in space dosimetry. The correct determination of the amp; 951; is not always straightforward especially when more strongly ionising radiation is to be measured. In the present work, the process of calculation of the amp; 951; based on two kinds of heavy charged particles was studied. Several factors which may influence the value of the amp; 951; and their significance for the final result were discussed. These include for example non uniform deposition of the dose within the detector volume, self attenuation of thermoluminescent light, choice of the reference radiation, etc. The presented approach was applied to the experimental results of amp; 951; of LiF Mg,Ti detectors irradiated with two kinds of heavy charged particles, protons and alpha particles. The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email journals.permissions oup.co

Practice patterns analysis of ocular proton therapy centers the international OPTIC survey

PURPOSE To assess the planning, treatment, and follow up strategies worldwide in dedicated proton therapy ocular programs. METHODS AND MATERIALS Ten centers from 7 countries completed a questionnaire survey with 109 queries on the eye treatment planning system TPS , hardware software equipment, image acquisition registration, patient positioning, eye surveillance, beam delivery, quality assurance QA , clinical management, and workflow. RESULTS Worldwide, 28,891 eye patients were treated with protons at the 10 centers as of the end of 2014. Most centers treated a vast number of ocular patients 1729 to 6369 . Three centers treated fewer than 200 ocular patients. Most commonly, the centers treated uveal melanoma UM and other primary ocular malignancies, benign ocular tumors, conjunctival lesions, choroidal metastases, and retinoblastomas. The UM dose fractionation was generally within a standard range, whereas dosing for other ocular conditions was not standardized. The majority 80 of centers used in common a specific ocular TPS. Variability existed in imaging registration, with magnetic resonance imaging MRI rarely being used in routine planning 20 . Increased patient to full time equivalent ratios were observed by higher accruing centers P .0161 . Generally, ophthalmologists followed up the post radiation therapy patients, though in 40 of centers radiation oncologists also followed up the patients. Seven centers had a prospective outcomes database. All centers used a cyclotron to accelerate protons with dedicated horizontal beam lines only. QA checks range, modulation varied substantially across centers. CONCLUSIONS The first worldwide multi institutional ophthalmic proton therapy survey of the clinical and technical approach shows areas of substantial overlap and areas of progress needed to achieve sustainable and systematic management. Future international efforts include research and development for imaging and planning software upgrades, increased use of MRI, development of clinical protocols, systematic patient centered data acquisition, and publishing guidelines on QA, staffing, treatment, and follow up parameters by dedicated ocular programs to ensure the highest level of care for ocular patient