Medical Physics

: 004: Clinical implementation and application of Monte Carlo methods in photon and electron dose calculation L. Aggarwal, S. Pradhan, N. Sharma, S. Sharma, A. Kajaria Institute of Medical Sciences (BHU), 1School of Biomedical Engineering Indian Institute of Technology (BHU) Varanasi, Uttar Pradesh, India, E-mail: [email protected] In radiotherapy, the dose delivered to patients needs to be determined before the treatment. Therefore, it is necessary to have an accurate method for predicting the dose distribution. In the past, planning computers calculate radiation dose using data obtained by measurement in a water phantom. This will lead to about 5% to 10% error in the situations where in homogeneity and lateral electron disequilibrium occur, especially in small field sizes. For these situations, Monte Carlo Simulation (MCS) has been proposed to give the most accurate solution. The first available MCS code for treatment planning was developed as part of the OMEGA project, which started in the early 90s by the National Research Council of Canada and the University of Wisconsin in Madison. The MCS code used was called EGS4 and it modeled the transport of photons and electrons. For radiotherapy, the BEAM system (which was based on EGS4) was used for modeling of radiotherapy sources. These days, EGS4 and BEAM have been replaced by their new versions EGSnrc and BEAMnrc. MCS models the transport of photon and electron by recording the interactions of each particle until it reaches the preset threshold energy. Therefore, MCS requires an extensive use of computer power. In the early 90s when the processing speed of computers was slow, one simulation would require several days before a result was available. The time required was impractical for clinical purposes. As an alternative deterministic dose calculation algorithms where developed for treatment planning. The Monte Carlo method has been shown through many research studies to calculate accurate dose distributions for clinical radiotherapy, particularly in heterogeneous patient tissues where the effects of electron transport cannot be accurately handled with deterministic dose calculation algorithms. Abstract: 005: Monte Carlo study of a flattening filter-free 6 MV varian linac using the BEAMnrc code A. Kajaria, N. Sharma, S. Sharma, S. Pradhan, L. Aggarwal School of Biomedical Engineering Indian Institute of Technology (BHU), 1Institute of Medical Sciences (BHU), Varanasi, Uttar Pradesh, India, E-mail: [email protected] In conventional linear accelerators, the flattening filter scatters and absorbs a large fraction of primary photons. Increasing the beam-on time, which also increases the out-of-field exposure to patients, compensates for the reduction in photon fluency. In recent years, intensity modulated radiation therapy has been introduced, yielding better dose distributions than conventional three dimensional conformal therapy. The drawback of this method is the further increase in beam-on time. An accelerator with the flattening filter removed, which would increase photon fluence greatly, could deliver considerably higher dose rates. The objective of the present study is to investigate the dosimeter properties of 6 MV photon beams from a Varian linear accelerator without a flattening filter. The dosimetry data were generated using the Monte Carlo programs BEAMnrc and DOSXYZnrc. We compared depth doses, dose rates, lateral profiles, and doses outside collimation for an accelerator with and without flattening filter. The study showed that unflattened beams have the following characteristics: a higher dose rate by factors of 2 on the central axis; lower out-of-field dose due to reduced head scatter and softer spectra and less variation of the shape of lateral dose profiles with depth. The findings suggest that with a flattening filter free accelerator better radiation treatments can be developed, with shorter delivery times and lower doses to normal tissues and organs. Abstract: 064: Postoperative strontium-90 beta irradiation in bulbar conjunctival carcinoma: A case series B. Dutta, R. Tudu, A. Halder, N. Biswas, D. Barman, P. Deb Medical College Hospital, Kolkata, West Bengal, India, E-mail: [email protected] Background: Conjunctival squamous cell carcinoma, a rare, slow growing malignancy, is associated with an unacceptably high rate of local recurrence after simple excision, prompting the use of various adjuvant treatments, including localised beta irradiation. Aim: Our case series aims to demonstrate the safety and efficacy of postoperative beta irradiation for bulbar conjunctival squamous cell carcinoma. Materials and Methods: From September 2013 to June 2015, a total of 11 patients (corresponding to 11 eyes with disease) were referred to us after primary surgical removal of a suspicious growth of the bulbar conjunctiva, followed by histopathological diagnosis of invasive or in-situ squamous cell carcinoma. Beta irradiation was given in a dose of 80 Gy in 10 fractions, 3 fractions per week. The machine used was a Strontium 90 β-ray applicator that has been in our centre since the 1950s. It consists of a circular strontium source mounted on a long handle, with an intervening Perspex disc meant to protect the treating doctor from the harmful effects of β-rays. The radioactive Strontium 90 and its decay product, Yttrium 90 are pure β emitters of low penetrating power, ideal for treatment of surface lesions, including conjunctival carcinoma. Regular follow up was done at our OPD for assessment of response, recurrence and adverse events. Results: After a relatively brief median follow up of 13 months, none of the patients showed locoregional recurrence, and none of them developed a cataract. Two of the patients reported local eye irritation and foreign body sensation during and after treatment, which were controlled with steroid-antibiotics and lubricant eye drops. No other adverse events were seen. Conclusion: Beta irradiation with a Strontium90 Applicator is a simple, yet remarkably safe and efficient method for local control of postoperative conjunctival carcinoma. However, a longer follow up with a larger number of patients would be a better assessment of the efficacy and safety of this method. Abstract: 068: Role of paperless clinic in modern radiotherapy practices A. Nachankar, M. Bhosale, V. Mhatre, P. Patwe, R. Patil, P. Dandekar Sir H. N. Reliance Foundation Hospital, Mumbai, Maharashtra, India, E-mail: [email protected] Background: Electronic medical records are safe & efficient data recording & verification system available in today's era. Aim: We conducted an audit of paperless radiotherapy processes in our institution to assess safety & efficiency of the systems. Materials and Methods: We use ARIA paperless system (VMS version 13.0) as the Oncology Information System right from the inception of the department of Radiation Oncology at our institution. The data entered in ARIA included diagnosis, simulation documents, scanned copy of consent and clinical assessment. We developed customized care path for workflow, prescription templates and dose constrains for at for and have developed customized and for in the care the patients clinical audit of processes and of the during at to In to several clinical system to patient treatment We conducted audit our from to for the patients Results: to data was care path was followed for and was Electronic prescription were used in templates were used in the were with customized Regular of treatment was was in with number of in system per patient to number of per patients were to which in clinical to per number of was and by radiation was done in The and was 10% and were Conclusion: Electronic records and verification system better data & it to radiotherapy treatment planning processes to and safety for radiotherapy Abstract: A of and in irradiation following D. D. D. M. M. M. India, E-mail: [email protected] Background: is an of treatment in is with the in the of in has been in the Aim: the of the and and and to assess the the Materials and Methods: A total of early patients right and were and were generated for each patient of using for a dose of in fractions at per were and of dose was done using with to small and large were also Results: better and of the and were in and large and were in of in was on in lower for of and reduced low dose of of and of reduced of No was the in of of and of In right the & of were in low dose and were less with In reduced the and of reduced the low dose and of No was in the Conclusion: dose in it was and the were or to in right irradiation it the of in in can be a better as it better dose Abstract: of and in D. D. Sharma, P. S. M. Institute of Medical India, E-mail: [email protected] Background: has its in many head and in better of are many of the new which is a of better and in as This study up to the of Aim: the in of and assessment of and for various based on the and Materials and Methods: of of and using planning to be delivered on linear were for For homogeneity doses, low dose and doses to at were time and number of were and were compared in the up data of the patient were to for Results: of and the patient showed better for with The dose at of the dose for total was for and for The delivery time was reduced for compared to was better with dose was high compared to An of was that the number of was less than for Conclusion: was better in It reduced treatment time and with of compared to Abstract: in situations Medical India, E-mail: [email protected] Background: of has the time. is by dose ideal are which have small and relatively from as in head and in most and normal are to each other and of the is as are In this study compared various and to factors the Aim: in doses in various factors that Materials and Methods: patients with in our department from to were of these patients were as as homogeneity and doses were Results: of patients of which and 11 were were & 3 and In in of as as were In in of or dose to Conclusion: is in where and are A has to be with to the or these factors to clinical needs to be Abstract: study based and based treatment planning for in M. S. S. R. Medical India, E-mail: [email protected] Background: planning methods for based on or based The is based on and dose of at by doses by on Radiation and and dose from planning. Aim: the in the and to the dose by and in the Materials and Methods: We the data for patients conventional and based The clinical and at were on and and were on We for based and conventional based of and in based Results: in based planning is lower compared to conventional planning better with conventional it is at the of higher dose to at The dose is times and dose is times higher in conventional planning compared to based planning. Conclusion: The conventional planning is to the planning in of it is at the of higher dose to and Abstract: modulated radiotherapy three dimensional conformal radiotherapy for irradiation in A study M. V. P. Medical College and Pradesh, India, E-mail: [email protected] Background: For irradiation in patients, three dimensional conformal radiotherapy and intensity modulated radiotherapy have in treatment However, the dose to at is the of in the Aim: This study dose and Materials and Methods: For patients and were generated for radiotherapy treatment. The dose was 2 to deliver in was for planning and dose to of dose were compared using Results: to of was than the of and of in and was and in and and homogeneity was and in and Gy of Gy of Gy of Gy of in right patients Gy of for patients was in Conclusion: was by the dose to were in as compared to that in it can be that is an efficient as as for the irradiation as compared to Abstract: an accurate in to in case of intensity modulated radiotherapy of A. Medical College and Pradesh, India, [email protected] Background: factors during radiotherapy including and patient and This lead to normal when a high dose to the is accurate treatment delivery is with and of the Aim: the of by after verification by Materials and Methods: verification of patients of was done by followed by before treatment delivery in for each In each was done using system and to were After the by was using system and to was three in the were in to a three dimensional Results: The from is with median and with median for and after to by in was by Conclusion: This study that with accurate compared to the be as the Abstract: modulated radiotherapy three dimensional conformal radiotherapy in A study A. P. L. V. M. Medical College and Pradesh, India, E-mail: [email protected] Background: radiotherapy is of treatment in and for have of various in radiotherapy In to deliver doses to these large of and are also included in the high dose normal which a in the treatment of dimensional conformal radiotherapy and intensity modulated radiotherapy are most used for which one is is Aim: of planning in irradiation in Materials and Methods: patients of referred for radiotherapy with which were in one were For these patients were also for study following Radiation Oncology of were compared on the of planning dose homogeneity and doses to at Results: was with the and was by and for and was better in than with was in the For was reduced in compared with In to and and to and were reduced by and for and and for in compared to No was in doses by of Conclusion: with and in reduction in doses by with better dose compared to that in be for in Abstract: of and in radiotherapy for P. R. P. A. P. D. A. Medical India, E-mail: [email protected] Background: is a with in with most patients with the in with the of treatment, the to long of radiation therapy which is an part of treatment, in this study proposed to 3 conformal radiotherapy and intensity modulated radiotherapy of patients in our and Materials and Methods: were generated for these patients and were compared with the by which the patients were for a dose of these patients been with with and in with the with The clinical included and and 2 The at for were the and The dose of were for the dose to at of and for 6 photons. Results: The dose and the of low doses were with the of high doses were less with doses were less with was in in of high was better with Conclusion: the large that as is the case in our the use of beams in to better to larger of small In is in the of at higher doses lower doses and be used with in patients with large Abstract: on of and of available for the treatment of head and D. S. R. S. Institute of Medical Medical India, E-mail: [email protected] Background: modulated radiotherapy is in the treatment of head and as the are in with the of the with is the of is an part of high radiotherapy intensity modulated radiotherapy for accurate of the patient and to the patient during the radiation therapy the up Aim: of and and system in head and assess the of on and to the the Materials and Methods: to have head and were to of the and the In the and were The was using and The and lower were also in of error and the patients were with and its was on the and was at the of treatment in the Results: The and was to be in of and in the and showed less in and in The total required was in the The in the was better in the system than the of than 3 required was were in the Conclusion: The total for and is less than in three In patients irradiation system is and was in of and Abstract: dose rate radiotherapy for the P. P. S. B. M. P. R. N. A. S. Hospital, E-mail: [email protected] demonstrate the medical in treatment of in Materials and Methods: radiation therapy with is the for the patients with have of and MV photons from linear compared with source machine with source of with of days requires source in has its to total time and will be with its The of the simulation and and followed for radiation and and about to planning that can with the Results: source is of The dose to and is to of dose of A and dose to is about of A. and are shorter treatment time, treatment on less reduced of applicator and safe It is a clinical and patients are the dose to shape of is a in Abstract: on the of for S. P. S. P. S. and Medical Research Mumbai, Maharashtra, India, E-mail: [email protected] Background: is on the of patient of Aim: The of this study is to investigate the of lower threshold dose and dose at on fluence verification of and Materials and Methods: data of & were with dose at 10% & For threshold & dose were using at dose at 3 to and dose at 2 and of with were for each exposure was the Results: Increasing threshold dose from up to showed in of & increase in to at which at & to at The number of which the of from at threshold dose to 11 at threshold dose the is to at 2 in and was with increase in threshold of the & at 10% & lower threshold dose to of of treatment with 10% lower threshold dose and of was better than for clinical However, when is the of was better than and Conclusion: are by the on the of of using 3 & 10% threshold dose is for clinical are at and and other relatively shape of a of threshold & to be Abstract: of up in head and patients by radiotherapy S. P. A. Institute and Research India, E-mail: [email protected] Aim: assess and the of up on and doses to at in head and patients by radiotherapy Materials and Methods: up in head and patients were by Two were the which was the and of the patients were to their at a the which was the of at a to up in and was to doses that would have been by and up were These 2 were and compared for and doses to Results: A total were for of up in The and error in and were and and and The study showed that was a in 2 The doses to various showed a increase in : The of up is for treatment in of delivery of doses to Abstract: of error and during treatment of D. S. A. M. N. P. S. Institute of Medical Uttar Pradesh, India, E-mail: [email protected] Background: radiotherapy is used in for of the be a error after the based that the are the of the treatment. This study the planning required for the error after and the in is the of the treatment. Aim: The of this study was to the error and of during the treatment of Materials and Methods: patients of 3 and with were included in this based based on A total of were for recording and were for and error based on the In the of the the planning and the were also to the Results: The for in and were and the for the error were and The error for and were and The was and the of was less than in and in the can be with a This has to be for as a during planning. Abstract: a conformal treatment for S. S. S. Institute of Medical India, E-mail: [email protected] Background: Postoperative radiotherapy in has to the with large based on is to treatment, and three dimensional treatment planning for a better with of with at Aim: The of this study was to conformal treatment for Materials and Methods: of were For each three treatment and were generated with photon beams MV for the total dose of Gy in the were to a and to the field in field was used when The was followed for and for These were compared and in of and & Results: for and were and was in these 3 was and for and dose of was in these 3 right was lower with as compared to and to and for were to be and for and for and and for dose to was and for and dose was and for and Conclusion: field This be necessary for treatment planning. Abstract: the using in radiotherapy S. S. A. D. N. S. Institute of Medical Uttar Pradesh, India, E-mail: [email protected] : radiotherapy for the A be to the and of each Aim: The of this study was to the using and in during conformal Materials and Methods: patients of with using based radiotherapy were included dimensional and of a were for each patient in planning The were in the verification for and in and of the were using these Results: The and of lateral for planning and were and for and for and for and for and and for The for were and for and for and for and for and and for the for planning and were and for and for and for and for and and for The based better compared to Abstract: and doses and doses in A R. R. V. M. H. P. M. S. India, E-mail: [email protected] Aim: The method of doses is by the for the doses to The of this study is to the the dosimetry and dosimetry for and its Materials and Methods: in been given the dose of and of patient for for and treatment planning done on treatment planning and were in and doses to the and been with and The data in and been to the and done for normal been for the in and done for the of the The linear for the dosimetry and Results: showed that data is and for and For and the is and for dose to The is and is for and for and The showed for and dosimetry is and for the For or Conclusion: This study that the dose data with dose data for and dosimetry be the alternative for the doses to the The that it is the dose to the as as it is the for and accurate dosimetry of and three dimensional and dosimetry is Abstract: in and implementation of in of for patients radiation body radiation therapy D. V. A. R. India, E-mail: [email protected] Background: has been a in treatment of to increase in normal Aim: is used to in which in reduced and normal This can in at We been using at were to of associated with Materials and Methods: was using an from of the on was determined for its shape was determined by number of given to with or without is by an of on in In is through and in a that patient can its and of during simulation as as during treatment. reduction in is by in of of or one with and with to Results: number of patients have been using this at our since its of was without and reduced of when was An reduction was in of Conclusion: can be used for reduction of in radiation treatment. It can in dose due to reduced and reduced normal Abstract: study to conformal conformal and conformal in radiation therapy for and M. B. S. R. R. S. Medical India, E-mail: [email protected] Aim: the of the three linear accelerator based radiotherapy conformal and conformal for the treatment of and Materials and Methods: of patients have been as or and with radiotherapy were for the For each data three one each with and were generated using The of of the for the and at were compared these three of Results: were patients with and patients with patients surgical of the to The and were three The of was in conformal field and where as it is in conformal The at are better in and compared to : This study that and deliver radiotherapy to and with better of and better of compared to Abstract: of in based using P. The of and in patients for various with based or radiotherapy using on Materials and Methods: patients were for treatment with using based was used for of and was used for and the of fractions of the patients were used to calculate and and were and Results: The and were in the in the and in the with a of an and of the and 3 The and were and an and of the and 3 Conclusion: In our with based with and compensates for Abstract: and implementation of and in radiotherapy S. Medical College and Hospital, India, E-mail: [email protected] The of this was to the and to and the for the radiotherapy are used to deliver the treating the are with safety which a in radiation The recent reported to exposure of radiation during up patient treatment as was on from control that is treatment the to a for of in the radiotherapy to have developed the and and radiotherapy and Materials and Methods: the and has been developed and in many the in the radiotherapy has to be from the to treatment and the has to be in the of the machine the in the radiotherapy have used the to the is of machine and as a radiotherapy machine and with also developed the which was with the by The of and the and with the The machine cannot be without the and the After of patient the needs to the after that is present in the treatment the is it an & for the treatment that will in the needs to the needs to the and also the However, the is before the or during treatment, the needs to the in to the Conclusion: The developed the and and the of the The was many and also and In clinical situations, treatment machine were during radiation treatment. exposure to the radiation without our can be by this We exposure could with our this us to protect from irradiation from radiotherapy As a of this has high time and

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