The experience of a developing country using an electronic portal imaging device for the verification of patient positioning and dosimetry in radiotherapy for prostate cancer. Issue 3 (5th March 2018)

• Record Type: Journal Article
• Authors: Farhat, Leila; Fourati, N.; Mnejja, W.; Daoud, J.
• Is Part Of: Journal of radiotherapy in practice. Volume 17:Issue 3(2018)
• Page Start: 297
• Page End: 301
• Publication Date: 2018-03-05
• Subjects: EPID, -- IMRT, -- portal dosimetry, -- portal imaging, -- prostate cancer; Radiotherapy -- Periodicals; 615.842005
• DOI: 10.1017/S146039691800002X
• Languages: English
• ISSNs: 1460-3969

Abstract

Abstract: Purpose: This is a retrospective study to evaluate the efficacy and safety of routine use of electronic portal imaging device (EPID) in intensity-modulated radiation therapy for localised prostate cancer. Materials and methods: Data from 20 patients with localised prostate cancer treated by radical radiotherapy using intensity-modulated technique in Habib Bourguiba Hospital were analysed to define the action levels for pretreatment planer dose distribution of 100 treatment fields and the set-up errors of 418 portal imaging. Pretreatment planar dose distribution was measured with the EPID. The additional dose from repeated portal imaging was determined with treatment planning system. Results: For all 100 fields, the predicted and the measured planar dose distribution agrees well with mean±standard deviation value for γ max =2·31±0·57, γ avg =0·36±0·07 and γ % ≤1=98·94%±0·71%, respectively. For the evaluation of set-up errors, the mean total errors with 1 SD in the lateral, longitudinal and vertical directions were 0·11±0·44 cm; 0·02±0·37 cm and −0·02±0·21 cm, respectively. The imaging additional dose was evaluated as 1 cGy per monitor unit. Conclusion: EPID is a useful tool to verify pretreatment dose distribution and to assess the correct field position without a significant increase in the absorbed dose due to the repetition of portal imaging.