1455 poster TLD AUDITS FOR NON-REFERENCE PHOTON AND ELECTRON BEAMS IN RADIOTHERAPY CENTERS IN POLAND

QA: AUDIT, RISK MANAGEMENT AND LEGAL ISSUES

the RTC list of technologies used in treatment, diagnostic support, pretreatment procedures, physical modification, medical physics service, quality assurance provision and patient and personnel protection planned (daily and annual) patient flow for every cancer type and nosological form regional features (territory size, population, climate, seismicity etc.) which should be taken into account RTC mission and facilities for treatment, research and education RTC structure (departments) and internal functional relations external functional relations list of basic equipment with specifications list of total equipment with specifications delivery, transport and installation conditions, technical characteristics, sizes, requirements for power supply, water supply, ventilation and other equipment information necessary for design layout requirements for the equipment installation and its efficient exploitation patient and personnel protection requirements, shielding requirements, radiation risk minimization medical physics service and maintenance requirements staffing requirements and justification comfortable working conditions requirements for the personnel and its placement preliminary cost estimating of RTC and construction stagesMuch attention should be paid to the realization of medical technology management. When purchasing equipment it’s necessary to implement strategic technology planning, technology assessment and technical audit, to develop equipment and technology management system, to train personnel and users. Results: The Russian experience has shown that if the scientific approach is used in RTC design, construction and modernization, the financial losses don’t exceed 10%-12% otherwise the losses are 87%-90%. Conclusions: The explicit initial data preparation and specific justification for the choice and purchase of the RTC equipment must be done in special documents "Medical Technical Requirements" (MTR) and "Medical Performance Specification" (MPS) which should be worked out by competent and independent specialists from research institutes or professional non-profit organizations. The vendors shouldn’t be involved in this process. 1453 poster RADIATION ONCOLOGY MODERNIZATION IN RUSSIA V. Kostylev1 2 , G. Matyakin3 , J. Mardynsky4 , G. Panshin5 , S. Tkachev6 1

I NSTITUTE OF M EDICAL P HYSICS AND E NGINEERING, Department of Radiotherapy, Moscow, Russian Federation A SSOCIATION OF M EDICAL P HYSICISTS OF RUSSIA, Department of Radiotherapy, Moscow, Russian Federation 3 2C ENTRAL C LINICAL H OSPITAL OF THE P RESIDENTIAL A DMINISTRATION OF THE RUSSIAN F EDERATION, Department of Radiation Oncology 4 M EDICAL R ADIOLOGICAL R ESEARCH C TR RAMS, Department of Radiation Therapy, Obninsk, Kaluga Reg., Russian Federation 5 RUSSIAN R ESEARCH X- RAY - R ADIOLOGY, Department of Radiation Therapy, Moscow, Russian Federation 6 RUSSIAN C ANCER R ESEARCH C ENTER, Department of Radiation Oncology, Moscow, Russian Federation 2

Purpose: It’s essential to improve the process of radiation oncology modernization in Russia. Materials: Today 75 percent of 140 radiotherapy departments available in Russia have a very poor level of equipment which doesn’t provide the adequate quality treatment. 20 percent of the departments ensure the satisfactory quality treatment and only 5 percent can deliver good quality radiotherapy. The number of medical accelerators is 10 times less than needed and the number of medical physicists is 6 times less than necessary. Only 15 percent of medical institutions have adequate medical physics service but only 3 percent (5 centers) provide highly qualified support to international standard. In Russia there is no radiotherapy clinic with the functioning quality assurance and technical audit systems which could be entitled to the status of the center of competence in compliance with the IAEA criteria. Because of the backwardness in radiation oncology only 30 percent of cancer patients receive radiotherapy instead of 70 percent requiring it and only 10 percent of them, who undergo treatment in 5 best radiotherapy departments, receive the adequate radiotherapy treatment, which make only 3 percent of all cancer patients. Results: Now the Government of Russia and other former Soviet republics take active measures in health care modernization, particularly in radiation oncology. The process of radiotherapy departments’ re-equipment and construction of new radiotherapy centers is essential for the efficient treatment of cancer patients. However, the modernization doesn’t bring the anticipated positive effect today. The situation analysis shows that in most cases the projects the way they are being realized don’t and can’t bring the anticipated positive results and the funds allotted for them are wasted. This situation is also typical for the former Soviet countries. It’s caused by the serious underestimation of our disastrous backwardness in the atomic medicine, insufficient officialdom competence, lack of scientific guidance, absence of regulation base and above all, the shortage of qualified medical physicists and radiologists. Conclusions: To liquidate more than 30-year backwardness in this field from the highly developed countries we’ll need a 20-year program covering the following measures: elaborate the strategy of radiation oncology modernization and development in Russia establish "growing points" in radiotherapy (technical upgrade of the leading cancer institutions, set-up of education research centers and scientific production associations to produce domestic

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equipment) organize personnel training system, continuing professional development and staff retention system take first aid measures on the system modernization of the existing radiotherapy departments construct 500 stateof-the-art radiotherapy centers apply the scientific approach to the planning and design of radiotherapy centers realize the quality assurance program, patient and personnel protection system, scientific and technical audit in radiotherapy elaborate, develop and produce competitive domestic equipment to cover 50 percent of the Russian radiology market. 1454 poster SIX YEARS EXPERIENCE OF AN INTERNAL INCIDENT REPORTING SYSTEM L. S. M. Conceicao1 , M. Araújo1 , F. Rocha1 , A. C. Oliveira1 , J. Gaspar1 , M. D. C. Lopes1 1 I NSTITUTO P ORTUGUÊS DE O NCOLOGIA DE C OIMBRA F RANCISCO G ENTIL , EPE, Medical Physics, Coimbra, Portugal Purpose: The Radiotherapy Department of our hospital has become an active department in ROSIS project during the year 2004. The motivation of professionals towards this process was based on safety and quality improvement rather than in error and punitive approaching. Since 2005, no reports have been included in the ROSIS database mainly because of the requirement for English translation. Nevertheless the internal reporting system has been maintained and actively stimulated. In the present work the experience of the last six years will be presented and evaluated highlighting its implication in the overall quality improvement of safety in radiotherapy. Materials: A report form based on the ROSIS Incident Form was developed to facilitate the process. The forms are available at each department site (treatment units, simulator, clinical dosimetry, mould room, clinical offices, etc.). They are monthly collected and analyzed. An internal database has been maintained in order to enable report keeping and global analysis. Most common reported errors or near misses are discussed at general or subsector meetings where correcting actions are proposed. Whenever a more serious incident is reported prompt action is carried out. A specific meeting is organized with the workers involved in the incident and all related professionals. An exhaustive analysis of all the causes and sub-steps of the incident sequence is done. Correcting actions are taken if possible and preventing procedures are developed. Results: In the period from 2005 to 2010, 7845 patients have been treated in three linear accelerators and 581 incidents have been reported. 88% of all reports corresponded to near-misses. In the remaining 12% just 3% were classified as accidents with significant dose consequences. The radiation technologists at the treatment units were those that mostly have reported (65%) followed by dosimetrists (20%) and physicists (10%). The areas of error detection were distributed as follows: treatment setup (43%); treatment plan verification (37%); image acquisition (9%); simulation (6%) and medical appointment (5%). The more severe accidents have systematically been reduced along the years through active corrective and preventive measures. Conclusions: Reporting of incidents stimulates alertness, awareness and responsibility. Periodic evaluation and good communication between professionals is the motor for keeping the process active. The perception and reporting of incidents lead to important changes towards quality and safety. 1455 poster TLD AUDITS FOR NON-REFERENCE PHOTON AND ELECTRON BEAMS IN RADIOTHERAPY CENTERS IN POLAND W. Bulski1 , J. Rostkowska1 , M. Kania1 , B. Gwiazdowska1 1 T HE M ARIA S KLODOWSKA -C URIE M EMORIAL C ANCER C ENTER, Department of Medical Physics, Warsaw, Poland Purpose: The Secondary Standard Dosimetry Laboratory (SSDL) of the Medical Physics Department of the Centre of Oncology in Warsaw has become a member of the IAEA/WHO international network of such laboratories in 1988. The SSDL has been carrying-out external postal TLD audits in teletherapy centres in Poland since 1991. Regular yearly audit runs have been carried out in reference conditions. Yearly audit runs have been extended to non reference conditions since 2003. The results of selected runs, performed during the period 2005 -2010, are presented. Materials: TLD system consists of Fimel PCL3 TLD automatic reader, Niewiadomski & Company LiF: Mg,Ti powder, IAEA holders, IAEA waterproof capsules, Unidos E with ion. chamber type PTW 30013, water phantom: MT - 150T (Med - Tec) and Co-60 unit - Theratron 780 E (Theratronics).After successful pilot runs in selected centres, a nation-wide run of the on-axis, off-axis measurements for symmetric open and wedged fields and for fields formed by MLC has been performed. In 2009 the run for asymmetric open and wedged fields were performed.The participants determined the doses with their treatment planning systems. TLD runs for on axis measurements in non-reference conditions were performed in Co-60 beams, in X-ray beams and in electron beams. The TLD capsules were irradiated at 10 cm and 5 cm (or 20 cm) depth for open fields (8x8 cm2 , 10x10 cm2 , 10x20 cm2 ) and wedged field (10x10 cm2 ) in Co-60 and X-ray beams. In electron beams the

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QA: I N VIVO DOSIMETRY

TLD capsules were irradiated at depth of dmax for 6x6 cm2 and 10x10 cm2 fields. TLD runs for off-axis measurements in non-reference conditions were performed in X-ray beams. The TLD capsules were irradiated at 10 cm depth for symmetric open and wedge fields (20x20 cm2 , +/- 5 cm off-axis). TLD runs for fields formed by MLC were performed in X-ray beams. The TLD capsules were irradiated at 10 cm depth for six MLC fields: reference, small, circular, inverted Y, irregular and irregular with wedge. TLD runs for off-axis measurements for asymmetric fields were performed in X-ray beams. The TLD capsules were irradiated at 10 cm depth. in various asymmetric set-ups. Results: The results of the audit in non-reference conditions for on-axis measurements are in the majority of cases within the 3.5% tolerance limit which is usually used for reference conditions.The nation-wide audit, for off-axis symmetric and asymmetric fields and the fields formed by MLC show that it is possible to keep the dose determination within the 5% limits by implementation of correct methodology and carefully carried-out measurements and calculations of doses. Conclusions: The methodology and results of the audit permit to introduce and maintain the audit program in non-reference conditions, for on-axis and off-axis measurements and for asymmetric fields, at the national level.

QA: In vivo dosimetry 1456 poster AN INVESTIGATION INTO THE USE OF IN-VIVO DOSIMETRY FOR VARIAN RAPIDARC TREATMENTS G. Verschoor1 , A. Vinall1 1 N ORFOLK AND N ORWICH U NIVERSITY H OSPITAL NHS T RUST, Department of Radiotherapy Physics, Norwich, United Kingdom Purpose: In-vivo diode Dosimetry for advanced treatment techniques such as IMRT has been used in this department for the last five years. The Department has recently commissioned Rapidarc (VMAT) treatments on two Varian linacs. The purpose of this work was to investigate the use of in-vivo Dosimetry techniques (TLD and diodes) to measure the dose delivered using RapidArc treatments. These complex treatments encompass the simultaneous movement of mlc leaves and gantry rotation so that field size and angle of incidence are constantly varying. Diodes require correction factors including field size, SSD, angle of incidence and temperature variation but their application is not straightforward with a rotational treatment technique. Hence, there is more variation in the measured dose and more scope for differences between planned and measured doses. TLDs require fewer correction factors but are sensitive to varying amounts of build-up. Materials: TLDs (Harshaw TLD-100) and diodes (Scanditronix EDP-15) were placed at intervals around the phantom. The TLDs had a build up cap or bolus to measure entrance dose at dmax. A Varian Clinac 2100EX was used to deliver rotational fields in clinical mode. Initial work has focused on a square field rotating around a cylindrical phantom (arc <180 degrees so that the dosimeter is not exposed to exit dose). Various arc angles and field sizes have been investigated. The raw dosimeter reading was corrected with an appropriate calibration factor and for the diode a correction factor for SSD. A comparison was made between the dosimeter reading and the value predicted by the treatment planning system (TPS). Results:

1457 poster DOSI-SECURE® : A NEW WIRELESS IN VIVO DOSIMETER FOR EXTERNAL RADIOTHERAPY G. Hangard1 , A. Canals2 , G. Sarrabayrouse3 4 , D. Lavielle2 , C. Chatry2 , A. Laprie1 I NSTITUT C LAUDIUS R EGAUD, Toulouse, France 2 TRAD, Labége cedex, France 3 U NIVERSITÉ DE TOULOUSE ; UPS, INSA, INP, ISAE ; UT1, UTM, LAAS ; F-31077, Toulouse Cedex 4, France 4 CNRS ; LAAS ; 7 AVENUE DU COLONEL R OCHE , F-31077, Toulouse Cedex 4, France 1

Purpose: We develop a new radiation dosimeter, named DOSI-SECURE®. He is dedicated to measure the entrance dose with a wireless reader and without specific calibration during radiotherapy treatment. This study concerns both evaluation of intrinsic parameters of the sensor under different irradiation configurations and preliminary tests using DOSI-SECURE®prototype. Materials: Intrinsic parameters have been validated with sensors packaged on Dual In Line (DIL) connected to a Source Monitor Unit (SMU) outside the treatment room. The dose measurements have been accomplished in a solid water equivalent phantom (PMMA) for photon beams of 6 and 18 MV (Clinac, Varian®). The tests were done under reference conditions: SAD of 100 cm, depth of 5 or 10 cm according to the energy and a field size of 10x10 cm. Initially, we began by defining the best reading time after irradiation by measuring a dose at 30 s and every minute up to 10 min. Then, we established the calibration curves for up to 300 dosimeters in order to evaluate stability and sensitivity of the response for a dose ranging from 0.5 to 20 Gy with steps of 0.5 Gy and 1 Gy. After that, we studied the response variation with clinical parameters (field sizes from 4 to 40 cm2 and SSD between 80 and 120 cm) and compared the depth curves achieved with an ionisation chamber. For the preliminary tests, we used the system completely, i.e. a skin patch with the sensor and a wireless reader. This detector incorporates a RFID (Radio Frequency Identification) system, with a PMOS dosimeter (P-channel Metal Oxide Semiconductor). Each detector will be associated to a patient and will record physically the dose received. The preliminary tests consisted in evaluating the variation of the dose response function to the beam angle variation. Results: The minimum time of reading after irradiation is 1 min. There is no significant difference between 1 and 10 min (<0.3 %). This result gives easily the possibility to use this sensor in a clinical routine. For a dose of 7 Gy, the fading after 150 h is less than 2 % and for a dose of 20 Gy, it falls in 1% after 500 h. The calibration curves (Figure 1) for 27 components with 0.5 Gy steps measurements shows a sensibility of 4mV/cGy at 1 Gy for 6 MV. The dispersion increases with the cumulated dose and the sensor saturation is more than 80 Gy. For the field size and for the SSD variations, the dose is less than ± 5 %. The depth curves for 6 and 18 MV match with the ionization chamber curves and the values are less than ± 2 % except in the first centimetre due to the build up. With the prototype, the response is less than 2 % between ± 20◦ , 5 % at ± 30◦ and more than 15% at ± 50◦ . This anisotropy shows in such point users will take precautions during measurements on a patient.

1. TLDs under bolus show good agreement (within ±5%) compared with the TPS, 2. Good agreement between TPS and the diode or TLD build up cap results were obtained by creating a plan with the build up cap/diode explicitly included. 3. When the build up cap/diode is included in the plan the agreement between the predicted TPS value and dosimeter reading improves from 15% to 4% for the TLDs, and from 20% to 6% for the diodes. Previous work in this department has indicated that it is possible to obtain results of measured v predicted doses within ± 5% for static IMRT fields with both diodes and TLDs. However, this is obtained by accurately positioning the dosimeter at a point of high dose and low dose gradient within the treatment field. Early results for Rapidarc fields on a cylindrical phantom and the dosimeter on the central axis have indicated measured doses of the order of 10-12% variation from predicted. Further work investigating different Rapidarc fields with varying modulation on both a cylindrical and a Rando phantom will be presented. Conclusions: Early investigation of both TLDs and diodes for the use of invivo dosimetry for Rapidarc is promising. However, because it is not possible to apply correction factors in the conventional way for diodes a wider tolerance level is proposed.

Conclusions: These first results show a good reproducibility of the dose response as well as a stability of measurements in time. The sensitivity observed with the DOSI-SECURE®dosimeter are suited to realize in vivo dosimetry during radiotherapy treatments and allows to confirm the interest of continuing the development of such a system. 1458 poster DOSIMETRIC CALIBRATION OF AN EPID USING THE ‘PORTDOSE’ PORTAL DOSIMETRY SOFTWARE P. Rixham1 , P. Crean1 , S. Weston1 , V. Cosgrove1 1 S T J AMES I NSTITUTE OF O NCOLOGY T HE L EEDS T EACHING H OSPITALS NHS T RUST, Leeds, United Kingdom