Dosimetry measurements with an intra-operative x-ray device

Abstract

The INTRABEAM 50 kV x-ray device can be used for intra-operative partial breast irradiation. Spherical applicators are added to the source probe to deliver a radially symmetric radiation dose. Dosimetric data for calculation of absorbed dose were measured for this unit and a superficial unit with a similar beam quality, as defined by half value layer (HVL). Chamber calibration factors, N(K), and chamber correction factors, k(ch), were determined based on HVL, according to the IPEMB code of practice and addendum. Depth doses were also measured using an ionization chamber and GafChromic EBT film. HVL was measured as 0.85-1.30 mm Al across the range of applicator sizes. Values for N(K) and k(ch) were found to be similar for the two units and all INTRABEAM applicator sizes. Therefore, calibration of ionization chambers, radiochromic film and other relative dosimeters could be performed on the superficial unit. This has the advantage of higher dose rates and lower dependence on small variations in detector positioning. Depth dose measurements performed using film also agreed with chamber values, published and manufacturer data, giving a simple and robust method for commissioning and regular quality assurance.

The Dosimetric Characteristics and Potential Limitation in Clinical Application of a Low Energy Photon Intra-Operative Radiotherapy System

“…The calculated dose value and the deviation will be very big in different tissue due to the spectrum chacteristics of the low energy photon (≤50 kV); the dose distribution will be influenced by the air gap between tissues and the applicator [14]. Monte Carlo modelling could be used in comparison with result from ionization chambers, radiochromic film and other dosimeters such as TLDs on the subsequent periodic QA tests for the INTRABEAM system [8]. There exist great difficulties for external beam radiotherapy when needed to supplement the postoperative radiotherapy especially for the accurate dose calculation and precise delineation of target and surrounding normal tissue irradiated especially for the nerves and blood vessels.…”

“…et al described the dosimetry of the INTRABEAM ® system with the spherical applicators [8]. Maxime Goubert et al have reported dosimetric behavior of the system equipped with flat and surface applicators [3].…”

“…Spherical applicators, a total number of 8 with 1.5 cm to 5.0 cm in diameter with 0.5 cm increment, are mainly used for the treatment of breast cancer [6]. Applicators consist of solid homogeneous polyether imide, which can be divided into two groups according to the structure mounted interiorly; the interior wall of the probe is embedded with a thin metal sheath for the applicators of diameter ≤3 cm whereas no metal sheath for those of diameter >3 cm [8]. Applicator size is decided according to tumor size and the diameter of surgical cavity where those of 4.0 -5.0 cm in diameters are relatively commonly used.…”

Therapeutic analysis of Intrabeam‐based intraoperative radiation therapy in the treatment of unicentric breast cancer lesions utilizing a spherical target volume model

“…In this still ongoing trial, patients were treated with either IB‐IORT or EBRT and outcomes were compared 8. Based on this trial and other studies, IB‐IORT has shown both benefits and drawbacks as compared to EBRT.…”

Feasibility study of insertable miniature x-ray source for dental imaging

“…그러나 최근에는 이러한 X선 튜 브를 작게 제작하여 다양한 부위에 적용하고자 기술 이 보고되고 있다 [2] . 표 1은 이러한 초소형 X선 튜브 의 개발 현황을 요약한 것이다 [2][3][4][5][6][7] . 이러한 초소형 X선 …”