Srivani Thatikonda, Presenter: Nothing to Disclose

Leela Krishnan MS, MD, FACRO, Abstract Co-Author: Nothing to Disclose

Eashwer K. Reddy MD, Abstract Co-Author: Nothing to Disclose

Fen Wang MD, PhD, Abstract Co-Author: Nothing to Disclose

calvin p myers PHD, Abstract Co-Author: Nothing to Disclose

Rajeev K. Badkul PhD, Abstract Co-Author: Nothing to Disclose

To Measure Skin Dose Using One Dose MOSFET Detector in breast cancer patients during high dose rate brachytherapy using multi-catheter technique. The primary end point is comparison of the skin dose readings obtained from TPS (treatment planning system) and with One Dose MOSFET.

It is known from previous studies that skin dose from radiotherapy is related to acute skin reaction and late effects such as pigmentation and telangiectasia . Skin dose delivered from high dose rate (HDR) brachytherapy is susceptible to inaccuracies and errors, including patient positioning, imaging, planning and dose delivery. Traditionally, TLD (Thermo luminescent dosimeter) is used in dosimetry for skin dose measurements . TLD is tedious to read, have delay time about 24 hrs. Besides its low cost, One Dose MOSFET can give immediate dose read out after irradiation and can be a great clinical QA tool. Its small size and thickness makes it suitable for near surface dose measurements unlike diodes or ion-chambers.We made 58 skin dose measurements in 13 patients with One Dose MOSFET s who underwent high dose rate brachytherapy using multi-catheter technique at KUMC. We collected skin doses from Nucletron PLATO TPS and One Dose MOSFET. We calibrated One Dose detector for Ir-192 HDR source in water phantom and corrected the measurements to get the skin doses.

The mean dose variation between One Dose and TPS is 6.3%. TPS was overestimating the skin dose by 6.3%. 25% of measurements were with in 5%, 50% were with in 5-11%, and 25% were in the range of 11-20%.

We concluded that TPS was overestimating the mean skin dose by 6.3%. The One Dose MOSFET provides fast, easy and adequate method of in vivo dosimetry for HDR brachytherapy.

Thatikonda, S, Krishnan, L, Reddy, E, Wang, F, myers, c, Badkul, R, To Analyze Skin Dose Measurements Using One Dose Mosfet Detector: An in Vivo Dosimetry to Verify Skin Doses in Breast Cancer Patients during High Dose Rate Brachytherapy.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/6001759.html