Dose-response variation among different populations

1992 ◽  
Vol 52 (5) ◽  
pp. 449-452 ◽  
Author(s):  
Iwan Darmansjah ◽  
Armen Muchtar
Keyword(s):  
Dose Response ◽  
Different Populations ◽  
Response Variation

scholarly journals Issues on VMAT QA Program with EBT3 Radiochromic Films: An improvement proposal

2019 ◽  
Vol 12 (3) ◽  
pp. 7
Author(s):  
Alisson Henrique Dal Col ◽  
Alexandre Nagao ◽  
William Alves Pinto Dos Santos ◽  
Geovani Pires Pena ◽  
Edilson Lopes Pelosi ◽  
...  
Keyword(s):  
Dose Response ◽  
Irradiation Time ◽  
Medical Physics ◽  
Intensity Modulated Radiotherapy ◽  
Cost Benefit ◽  
Radiochromic Film ◽  
Time Interval ◽  
Direct Function ◽  
Gamma Analysis ◽  
Response Variation

EBT3 radiochromic film is renowned in medical physics field due its dose verification for Quality Assurance (QA) program in intensity-modulated radiotherapy (IMRT). However, it is known that QA programs, which include these films, are expensive and relatively time-consuming. Furthermore, it was noted that dosimetry with EBT3 film has been suffering with lack of accuracy. In that way, it was evaluated its possible dosimetric inaccuracy, the time expenditure in the whole QA process, as well as the cost-benefit of such a program and it is suggested efforts to improve this process based on our institution expertise. A retrospective study was performed on VMATplans, rating how many cases got success by absolute dosimetric Gamma analysis. Furthermore, in order to verify the film intra-lot aging, the calibration curves were compared to the lot fabrication date. On the other hand, with single- and multi-channel dosimetric analyses, further trials were performed over the post-irradiationsaturation curves up to 35 h after irradiation. The retrospective Gamma analyses exhibited that about 23% of the total VMAT cases did not passed by absolute Gamma evaluation. It was seen that the fabrication date influences the dose response, which prerequisites a calibration curve for each film box. For the multichannelanalyses, as excepted, the red channel sensitivity was the highest for doses up to 5 Gy. Moreover, it was reinforced that the dose response is a direct function of dose level for both types of analyses. In that way, it was chosen a post-irradiation time interval of 12h-16h, with dose response variation criteria less than 2%. Finally, it was verified, based on our routine, that there were about 23h/month expended in a film QA program and directly costs bordering US$20,000.00/year.

SU-E-T-108: EBT2 Film Based Dosimetry Incorporating Correction for Spatial-Temporal Dose Response Variation

2011 ◽  
Vol 38 (6Part12) ◽  
pp. 3510-3511
Author(s):  
S Tenn ◽  
D Ruan ◽  
T Dou ◽  
D Low
Keyword(s):  
Dose Response ◽  
Response Variation ◽  
Ebt2 Film

A study of dosimetric characteristics for in vivo dosimetry with cylindrical n-type Isorad diode

2013 ◽  
Vol 13 (1) ◽  
pp. 45-59
Author(s):  
Kashif Islam ◽  
Asdar Haque ◽  
Khan Muhammad ◽  
Sohail Murad ◽  
Muzaffar Hussain ◽  
...  
Keyword(s):  
Dose Response ◽  
Conversion Factor ◽  
Field Size ◽  
In Vivo Dosimetry ◽  
Correction Factors ◽  
Dose Verification ◽  
Signal Stability ◽  
Response Variation ◽  
Good Signal

AbstractBackground and purposeThe objective was to determine diode characteristics before actual dose verification on human phantom and patients.Materials and methodsThe reliability and stability of equipment, signal stability, precision, dose response linearity, field flatness, perturbation of radiation dose, plastic to water conversion factor (Kpl), ionisation chambers (ICs) and diode calibration were determined. Correction factors for tray (CFtray), wedge (CFwedge), field size (CFFS), SSD (CFSSD), angle (CFangle) and block (CFblock) were found. Patient dose monitor, Isorad diode (n-type) and IC (PTW Frieburg), Co-60 unit (Theratron), ATOM Adult male human phantom (Model 701-D, CIRS) were used.Results and conclusionGood signal stability, precise data, and linear dose response, variation of 0·500% and 5·000% in field flatness and perturbation tests, respectively, were noted. Kpl was 1·006 for IC PTW Frieburg TW30013, 0114. The diode calibration factor was 0·989. CFtray, CFFS, CFSSD, CFangle, CFblock were 1·001, 1·001, 0·997, 1·006 and 0·990, respectively. CFwedge were 1·024, 1·030 and 1·038 for 30°, 45° and 60° wedges, respectively. The verification of above correction factors (CFs) on Nasopharynx and lung of human phantom was also done.

Dose-Response Relationships to Pancreozymin in Normal Subjects and Patients with Chronic Pancreatitis

1963 ◽  
Vol 45 (2) ◽  
pp. 209-214 ◽  
Author(s):  
Donald H. Hanscom ◽  
Armand Littman ◽  
Jack V. Pinto
Keyword(s):  
Chronic Pancreatitis ◽  
Dose Response ◽  
Normal Subjects
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