1. MALIK YOUNAS IMRAN - Institute of Physics (IoP), The Islamia University of Bahawalpur, Pakistan.
2. MUHAMMAD ASGHAR GADHI - Bahawalpur Institute of Nuclear medicine and Oncology, Bahawalpur, Pakistan.
3. SAEED AHMAD BUZDAR - Institute of Physics (IoP), The Islamia University of Bahawalpur, Pakistan.
4. MUHAMMAD ARSHAD - Bahawalpur Institute of Nuclear medicine and Oncology, Bahawalpur, Pakistan.
5. IFTIKHAR ALAM - Bahawalpur Institute of Nuclear medicine and Oncology, Bahawalpur, Pakistan.
6. LAILA SUMREEN - University College of Conventional Medicine, The Islamia University of Bahawalpur, Pakistan.
7. SAIMA ALTAF - Institute of Physics (IoP), The Islamia University of Bahawalpur, Pakistan.
Purpose: This study aims for output verification and to validate the dosimetric performance of Varian vertical-type surface applicators using a Farmer-type ion chamber for high-dose-rate (HDR) 192Ir brachytherapy. Materials and Methods: Varian’s vertical-type surface applicators are used at two different dwell positions (d.p) with the source center located at -10 mm and at -15 mm from the centre of first nominal dwell position. Measurements are performed using a Farmer-type ion chamber at 5 mm depth and compared with vendor data and TPS generated values. Relative dosimetry using gafchromic film was performed at 4 mm depth in phantom. The therapeutic area was determined as a full width at 90% dose level. Results: For d.p -15 mm, the measurements showed 9% agreement with vendor data and 5% with TPS calculations. The smallest applicator, SA10, showed poor agreement (percent difference ~14%) compared to vendor data. For the d.p -10 mm, the result reveals the reduced agreement; 13% with vendor data and 6% with TPS calculations. The results from full width measurement at 90% dose level agreed within 2 mm with vendor data and 3 mm with TPS values. The PDD curves showed good agreement for both the vendor data and TPS predictions. Conclusion: This study demonstrates an easy, simple and independent way to verify the output dose measured with Leipzig-style, Varian vertical-type surface applicators. The results validate the performance of these applicators for accurate dose delivery and the treatment of skin cancer, ultimately improving the quality of work and patient care.
Surface Applicator, Farmer Ion Chamber, Dosimetry, HDR Brachytherapy, Ir-192 Source, Percent Depth Dose, Skin Cancer.