Verification of dose parameters under reference and non-reference conditions for radiotherapy in Liaoning province / 中华放射医学与防护杂志

Objective To verify the reliability of dose parameters of radiotherapy under reference and non-reference conditions by using TLD.Methods Dose parameters were verified by using TLDs under reference and non-reference conditions,including the maximum dose in axel of 5 electron beams with energy of 9 MeV and the variations of dose by depth,source-skin distance,exposure field and 45° wedge for 10 photon beams with energy of 6 MV in 5 hospitals.Results The average relative deviation of 6 MV photon beam measured between TLDs and finger ionization chambers were 4.45％,within ± 7％ as required by IAEA.The average relative deviation of 9 MeV electron beam measured between TLDs and plane parallel chambers were 2.45％,within ± 5％ was required by IAEA.Conclusions Measuring dosimetric parameters by using TLDs under reference and non-reference conditions was reliable and feasible.

Dosimetric verification for radiotherapy quality audit under reference and non-reference conditions in Jiangsu province / 中华放射医学与防护杂志

Objective To verify the methodology for auditing dosimetric parameters in reference and non-reference conditions with thermoluminescent dosimeters (TLDs).Methods Under reference and non-reference conditions,the established TLD methods were used to observe the absorbed dose variations with depth,SSD,field size and 45 wedges for 10 photon beams at 5 hospitals.Dosimetric parameters,including doses at Dmax points in axis,on 5 electron beams of 9 MeV were measured.The measurement results were compared between the TLDs and plane parallel ionization chambers.Results For 6 MV photon beams,the relative deviation of between finger ionization chamber method and TLD chips was in the range of-1.7％ to 5.4％ under on-axis non-reference conditions,and-6.3％ to-0.6％ under off-axis non-reference conditions,respectively,all within the range of ≤ ± 7％ as required by the IAEA.The relative deviation between plane parallel chamber and TLD method was-2.3％ to 3.7％,within ± 5％ as required by the IAEA.Conclusions It is convenient and feasible to use TLD method for quality audits of dosimetric parameters in radiotherapy.

TLD-based quality audit for radiotherapy dosimetry under reference and non-reference condition in Henan province / 中华放射医学与防护杂志

Objective To verify the reliability of radiotherapy dosimetric parameters in reference and non-reference conditions using thermoluminescent dosimeters (TLDs).Methods Using the established TLD method,the dose variations with different radiation field sizes and 45 ° wedge plate were verified for 10 photon beams of 6 MV,together with dosimetric parameters at the point of maximum axial dose for 4 electron beams of 9 MeV under reference and non-reference conditions.Comparisons were made between TLD results and finger ionization chamber results.Results The average relative deviation,for 6 MV photon beams,between TLD results and finger ionization chamber measurements was 4.7％,within ± 7％ as required by the IAEA.The average relative deviation,for 9 MeV electron beam,between TLD results and plane parallel ionization chamber measurements was 2.4 ％,not beyond ± 5％ permitted by IAEA.Conclusions Using TLD method to verify the radiotherapy dosimetric parameters in reference and non-reference conditions was reliable,simple and feasible.