Abstract book - ESTRO meets Asia

S37 ESTRO meets Asia 2018

PV-091 Evaluation of Inter fraction and Intra fraction motion in head and neck Malignancy M. Sharma 1 , A. Bahl 1 , A.S. Oinam 1 , A. Elangovan 1 , R. Miriyala 1 , C. Dracham 1 , S. Ghoshal 1 1 Post Graduate Institute of Medical Education and Resear ch, Radiotherapy, Chandigarh, India Purpose or Objective Conformal Radiotherapy techniques are used to improve dose conformity around the target volume without increasing toxicities to the organs at risk. For these precision treatment techniques, set up accuracy and treatment verification using image guidance are inevitable. Set up verification can be done either online or offline. We have done the present study with an aim to generate the inter fraction and intra fraction errors seen in our practice during the treatment of Head and Neck cancers and to generate Planning Target Volume (PTV) margins based on these errors. Material and Methods It is a prospective study involving twenty-five patients of locally advanced head and neck cancers who underwent conformal Radiotherapy using Intensity Modulated Radiation Therapy (IMRT). Patients were immobilsed using thermoplastic cast (S-type). Set up was verified under image guidance. Inter fractional errors were corrected prior to treatment and post treatment cone beam computed tomography (CBCT) was acquired to assess intra fractional errors. The documented errors were entered into SPSS v20 for statistical analysis. Results The magnitude of inter fraction errors (Mean ± SD) were - 0.011±0.846, 0.014±0.256, 0.056±0.025 in vertical, longitudinal and lateral axes respectively. Similarly, intra fraction errors (Mean ± D) were -0.15±0.07, 0.032 ±0.80, and 0.019±0.04 in vertical, longitudinal and lateral axis respectively. The mean PTV margins calculated using Van Herk formula were 0.28mm, 0.29mm and 0.16mm in anteroposterior, craniocaudal and transverse directions, respectively. Conclusion Based on this analysis, we recommend a PTV margin of 5mm for head and neck patients undergoing IMRT. We strongly advice such analysis in institutes performing precision radiotherapy techniques for reducing the PTV margins. PV-092 Determination angles of breast board in 100 patients undergoing rt in ca breast with tangents A. Singh 1 , G. Rath 1 , H. Singh 2 1 Aiims, Radiation Oncology, Delhi, India 2 Pgimer, Radiation Oncology, Chanigarh, India Purpose or Objective The goal of radiotherapy is to deliver accurate radical dose to the predetermined Planned Target Volume. The accurate dose delivery depends on the accuracy in the determination of parameters of dose calculation, daily patient position-set-up, reproducibility and accurate choosing of Immobilization parameter etc. Cranio caudal contour of female breast patients incline superiorly. It limits the alignment of breast tangential beams. Even if collimator angles are used to align the beams on the skin of patients, TPS and CT Simulator data shows the increase of misalignment. The inclination angle of cranio caudal contour of sternum are to be made in horizontal position so that no collimation angles are applied to tangential fields. Breast wedge of adjustable angle is generally used to make sternum horizontal. Minimum angle of 5 degree interval between the two successive angle positions is seem to be sufficient for positioning of breast patients

Material and Methods 100 patients were treated in the department of Radiotherapy, PGIMER, Chandigarh. Conventional breast wedge with 20 degree angle was used for patient positioning. The angle of individual patient was measured by manually method. Patient were laid down on the treatment couch with arm rest fixed on the couch with respect to ipsilateral breast side. The arm of patient of the side to be treated abducted at 90 degree from the patient body and flexed at elbow with the help of arm rest. Wooden board and wooden breast wedge are used to align the sternum horizontal. The angle of wooden board and wooden breast board are adjusted manually and measured the respective angle Results In general there is no gross change in patient position setup within 5 0 angle difference between two successive positions. The patient position can be adjusted at the same level upto the angle difference of 5 0 by moving the head and or foot end. Breast wedge adjustable from 5 0 to 30° with the angle interval of 5 0 is found to be adequate for graduation of angular scale. If to breast wedge of standard angle are chosen two breast wedge of standard angle 15 0 and 25 0 are found to be better. For three breast wedge of standard angle chosen for construction then it is better to construct of 10° 20° and 30° angle. Single standard breast wedge is adequate to construct of 25 0 breast wedge to make crano-caudal contour along with sternum horizontal. Conclusion patient is indexed to the breastboard for reproducible set- up to elevate the patient’s upper torso above the treatment couch to bring the sternum parallel to the table to conclude & creates a uniform surface dose distribution across the treatment area. PV-093 New Zealand radiation therapist’s perceptions of peer group supervision G. Dungey 1 , H. Neser 1 1 University of Otago-Wellington, Radiation Therapy, Wellington, New Zealand Purpose or Objective International and New Zealand (NZ) studies indicate that radiation therapists (RTs) are at risk of burnout and some have poor coping strategies when it comes to managing work related stressors. An effective way of helping staff with these stressors is peer group supervision (PGS). This differs from more traditional forms of counselling/clinical supervision in that it doesn't require the presence of a qualified, identified expert in the process (a counsellor/clinical supervisor). It usually involves reciprocal arrangements in which peers commit to work together for mutual benefit. To be effective it is recommended that staff taking part are given formal guidance to manage the groups and that the process is evaluated regularly. The literature advocates that PGS results in increased professionalism and patient care within the work environments. The aim of this research was to evaluate NZ RT’s perceptions of participating in PGS. Material and Methods Over 100 RTs across five radiation therapy departments in NZ agreed to participate in PGS and to be a part of a formal evaluation. Thirty-six representatives from each of the five centres attended one of two training workshops facilitated by the New Zealand Coaching & Mentoring Centre held in July and August in 2017. The formal evaluation utilised the Clinical Supervision Evaluation Questionnaire (CSEQ), which is a 14 item, evaluation tool, an optional open-ended question and participant demographics. The CSEQ measures staff perceptions of purpose, process and impact of PGS. The questionnaire was sent to 109 participants utilising an anonymous