J M Park1, J Lee, H S Kim, S-J Ye, J-I Kim. 1. 1 Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea.
Abstract
OBJECTIVE: To develop an applicator for in vivo measurements of lens dose during radiotherapy. METHODS: A contact lens-shaped applicator made of acrylic was developed for in vivo measurements of lens dose. This lens applicator allows the insertion of commercially available metal oxide semiconductor field effect transistors (MOSFETs) dosemeters. CT images of an anthropomorphic phantom with and without the applicator were acquired. Ten volumetric modulated arc therapy plans each for the brain and the head and neck cancer were generated and delivered to an anthropomorphic phantom. The differences between the measured and the calculated doses at the lens applicator, as well as the differences between the measured and the calculated doses at the surface of the eyelid were acquired. RESULTS: The average difference between the measured and the calculated doses with the applicator was 3.1 ± 1.8 cGy with a micro MOSFET and 2.8 ± 1.3 cGy with a standard MOSFET. The average difference without the lens applicator was 4.8 ± 5.2 cGy with the micro MOSFET and 5.7 ± 6.5 cGy with the standard MOSFET. The maximum difference with the micro MOSFET was 10.5 cGy with the applicator and 21.1 cGy without the applicator. For the standard MOSFET, it was 6.8 cGy with the applicator and 27.6 cGy without the applicator. CONCLUSION: The lens applicator allowed reduction of the differences between the calculated and the measured doses during in vivo measurement for the lens compared with in vivo measurement at the surface of the eyelid. ADVANCES IN KNOWLEDGE: By using an applicator for in vivo dosimetry of the eye lens, it was possible to reduce the measurement uncertainty.
OBJECTIVE: To develop an applicator for in vivo measurements of lens dose during radiotherapy. METHODS: A contact lens-shaped applicator made of acrylic was developed for in vivo measurements of lens dose. This lens applicator allows the insertion of commercially available metal oxide semiconductor field effect transistors (MOSFETs) dosemeters. CT images of an anthropomorphic phantom with and without the applicator were acquired. Ten volumetric modulated arc therapy plans each for the brain and the head and neck cancer were generated and delivered to an anthropomorphic phantom. The differences between the measured and the calculated doses at the lens applicator, as well as the differences between the measured and the calculated doses at the surface of the eyelid were acquired. RESULTS: The average difference between the measured and the calculated doses with the applicator was 3.1 ± 1.8 cGy with a micro MOSFET and 2.8 ± 1.3 cGy with a standard MOSFET. The average difference without the lens applicator was 4.8 ± 5.2 cGy with the micro MOSFET and 5.7 ± 6.5 cGy with the standard MOSFET. The maximum difference with the micro MOSFET was 10.5 cGy with the applicator and 21.1 cGy without the applicator. For the standard MOSFET, it was 6.8 cGy with the applicator and 27.6 cGy without the applicator. CONCLUSION: The lens applicator allowed reduction of the differences between the calculated and the measured doses during in vivo measurement for the lens compared with in vivo measurement at the surface of the eyelid. ADVANCES IN KNOWLEDGE: By using an applicator for in vivo dosimetry of the eye lens, it was possible to reduce the measurement uncertainty.
Authors: Christian Ehringfeld; Susanne Schmid; Karin Poljanc; Christian Kirisits; Hannes Aiginger; Dietmar Georg Journal: Phys Med Biol Date: 2005-01-21 Impact factor: 3.609
Authors: Yuichi Akino; Indra J Das; Gregory K Bartlett; Hualin Zhang; Elizabeth Thompson; Jennifer E Zook Journal: Med Phys Date: 2013-01 Impact factor: 4.071