A new formalism for reference dosimetry of small and nonstandard fields

Medical Physics - Tập 35 Số 11 - Trang 5179-5186 - 2008
Rodolfo Alfonso1, Pedro Andreo2, R. Capote3, M. Saiful Huq4, W Kilby5, Per Kjäll6, T Mackie7, Hugo Palmans8, K E Rosser9, Jan Seuntjens10, Wolfgang Ullrich11, Stanislav Vatnitsky3
1International Atomic Energy Agency, A-1400 Vienna, Austria and Instituto Nacional de Oncologia y Radiobiologia, CP 10400 La Habana, Cuba
2International Atomic Energy Agency, A‐1400 Vienna, Austria and University of Stockholm‐Karolinska Institutet, SE‐17176 Stockholm, Sweden
3International Atomic Energy Agency, A-1400 Vienna, Austria
4University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania 15232
5Accuray Inc., Sunnyvale, California 94089
6Elekta Instrument AB, SE-10393 Stockholm, Sweden
7Department of Medical Physics, University of Wisconsin, Madison, Wisconsin 53706.
8National Physical Laboratory, Teddington, Middx TW11 0LW, United Kingdom and Slovenský Metrologický Ústav, SK-84255 Bratislava, Slovakia
9Royal Marsden NHS Foundation Trust, Sutton, Surrey SM2 5PT, United Kingdom
10Medical Physics, McGill University, Montreal, Québec H3G 1A4, Canada
11BrainLAB AG, D-85622 Feldkirchen, Germany

Tóm tắt

The use of small fields in radiotherapy techniques has increased substantially, in particular in stereotactic treatments and large uniform or nonuniform fields that are composed of small fields such as for intensity modulated radiation therapy (IMRT). This has been facilitated by the increased availability of standard and add‐on multileaf collimators and a variety of new treatment units. For these fields, dosimetric errors have become considerably larger than in conventional beams mostly due to two reasons; (i) the reference conditions recommended by conventional Codes of Practice (CoPs) cannot be established in some machines and (ii) the measurement of absorbed dose to water in composite fields is not standardized. In order to develop standardized recommendations for dosimetry procedures and detectors, an international working group on reference dosimetry of small and nonstandard fields has been established by the International Atomic Energy Agency (IAEA) in cooperation with the American Association of Physicists in Medicine (AAPM) Therapy Physics Committee. This paper outlines a new formalism for the dosimetry of small and composite fields with the intention to extend recommendations given in conventional CoPs for clinical reference dosimetry based on absorbed dose to water. This formalism introduces the concept of two new intermediate calibration fields: (i) a static machine‐specific reference field for those modalities that cannot establish conventional reference conditions and (ii) a plan‐class specific reference field closer to the patient‐specific clinical fields thereby facilitating standardization of composite field dosimetry. Prior to progressing with developing a CoP or other form of recommendation, the members of this IAEA working group welcome comments from the international medical physics community on the formalism presented here.

Từ khóa


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Thông tin
Thông tin xuất bản

Medical Physics

Tập 35 Số 11

5179-5186

Thông tin tác giả