PO-1542 Influence of abdominal air cavities on the dose distribution of daily-adapted plans

2021 ◽  
Vol 161 ◽  
pp. S1266
Author(s):  
F. Belosi ◽  
M. Bogowicz ◽  
M. Chamberlain ◽  
S. Ehrbar ◽  
H. Garcia Schüler ◽  
...  
Keyword(s):  
Dose Distribution ◽  
Air Cavities

Evaluation of air cavities on dose distributions with air-filled apparatuses having different volumes using Gafchromic EBT3 films in brachytherapy

2018 ◽  
Vol 17 (4) ◽  
pp. 411-416
Author(s):  
Mehmet Bahadır Çelik ◽  
Nezahat Olacak ◽  
Songül Barlaz Us ◽  
Emin Tavlayan
Keyword(s):  
Dose Distribution ◽  
Dose Effect ◽  
Water Medium ◽  
Special Device ◽  
Dose Distributions ◽  
Clinical Dose ◽  
Depth Dose ◽  
Gafchromic Films ◽  
Depth Dose Curve ◽  
Air Cavities

AbstractAimThe data used in brachytherapy planning are obtained from homogeneous mediums. In practice, the heterogeneous tissues and materials affect the dose distribution of brachytherapy. It is aimed to investigate the effect of air cavities on brachytherapy dose distribution using a specially designed device.Material and methodsIn this study, the special device designed with different volumes of air and water to be irradiated and measured at different depths using EBT3 Gafchromic films. EBT3 Gafchromic films were preferred for this study because they can be cut to the shape of the experimental geometry, are water resistance and double directional usability.ResultsIn our study, sudden dose increases and decreases were observed at the water–air–water interfaces. Increases were 9, 11·8 and 15% in the 13, 18 and 22 mm apparatus, respectively. These effects were expected and the results were consistent with the literature and within the tolerance limits stated in the clinical dose guidelines. The most important result is that the percent depth–dose curve of the radiation passing through the air to the water and only passing through the water medium is different. The average differences were 1·97, 2·97 and 2·31% for the 13, 18 and 22 mm apparatus, respectively.ConclusionAlthough the effect of heterogeneity may be neglected according to clinical guidelines, it is suggested that the dose effect of heterogeneity is taken into account so that the dose can be estimated sensitively. Brachytherapy plans using dose data without considering air gaps may cause erroneous dose distributions due to heterogeneity of tissue.

scholarly journals Investigating the Effect of Air Cavities of Sinuses on the Radiotherapy Dose Distribution Using Monte Carlo Method

2019 ◽  
Vol 9 (1Feb) ◽  
Author(s):  
F Seif ◽  
M R Bayatiani ◽  
S Hamidi ◽  
M Kargaran
Keyword(s):  
Monte Carlo ◽  
Dose Distribution ◽  
Sphenoid Sinus ◽  
Neck Region ◽  
Cavity Size ◽  
Air Cavity ◽  
Head And Neck Region ◽  
Radiotherapy Dose ◽  
Dose Deposition ◽  
Air Cavities

Background: Considering that some vital organs exist in the head and neck region, the treatment of tumors in this area is a crucial task. The existence of air cavities, namely sinuses, disrupt the radiotherapy dose distribution. The study aims to analyze the effect of maxillary, frontal, ethmoid and sphenoid sinuses on radiotherapy dose distribution by Monte Carlo method.Materials and Methods: In order to analyze the effect of the cavities on dose distribution, the maxillary, frontal, ethmoid and sphenoid sinus cavities were simulated with (3×3.2×2) cm3, (2×2×3.2) cm3, (1×1×1.2) cm3 and(1×1×2) cm3 dimensions.Results: In the analysis of the dose distribution caused by cavities, some parameters were observed, including: inhomogeneity of dose distribution in the cavities, inhomogeneity of dose on the edges of the air cavities and dispersion of the radiations after the air cavity. The amount of the dose in various situations showed differences: before the cavity a 0.64% and a 2.76% decrease, a 12.06% and a 17.17% decrease in the air zone, and a 2.25% and a 5.9% increase after the cavity.Conclusion: The results indicate that a drop in dose before the air cavities and in the air zone occurs due to the lack of scattered radiation. Furthermore, the rise in dose was due to the passage of more radiation from the air cavity and dose deposition after the air cavity. The changes in dose distribution are dependent on the cavity size and depth. As a result, this has to be noted in the treatment planning and MU calculations of the patient.

scholarly journals Investigating the Effect of Air Cavities of Sinuses on the Radiotherapy Dose Distribution Using Monte Carlo Method

2019 ◽  
Vol 9 (1Feb) ◽  
Author(s):  
F Seif ◽  
M R Bayatiani ◽  
S Hamidi ◽  
M Kargaran
Keyword(s):  
Monte Carlo ◽  
Dose Distribution ◽  
Sphenoid Sinus ◽  
Neck Region ◽  
Cavity Size ◽  
Air Cavity ◽  
Head And Neck Region ◽  
Radiotherapy Dose ◽  
Dose Deposition ◽  
Air Cavities

Background: Considering that some vital organs exist in the head and neck region, the treatment of tumors in this area is a crucial task. The existence of air cavities, namely sinuses, disrupt the radiotherapy dose distribution. The study aims to analyze the effect of maxillary, frontal, ethmoid and sphenoid sinuses on radiotherapy dose distribution by Monte Carlo method.Materials and Methods: In order to analyze the effect of the cavities on dose distribution, the maxillary, frontal, ethmoid and sphenoid sinus cavities were simulated with (3×3.2×2) cm3, (2×2×3.2) cm3, (1×1×1.2) cm3 and(1×1×2) cm3 dimensions.Results: In the analysis of the dose distribution caused by cavities, some parameters were observed, including: inhomogeneity of dose distribution in the cavities, inhomogeneity of dose on the edges of the air cavities and dispersion of the radiations after the air cavity. The amount of the dose in various situations showed differences: before the cavity a 0.64% and a 2.76% decrease, a 12.06% and a 17.17% decrease in the air zone, and a 2.25% and a 5.9% increase after the cavity.Conclusion: The results indicate that a drop in dose before the air cavities and in the air zone occurs due to the lack of scattered radiation. Furthermore, the rise in dose was due to the passage of more radiation from the air cavity and dose deposition after the air cavity. The changes in dose distribution are dependent on the cavity size and depth. As a result, this has to be noted in the treatment planning and MU calculations of the patient.

Seed dormancy and germination requirements in Angelica palustris (Besser) Hofm., a critically endangered plant

2018 ◽  
Vol 44 (4) ◽  
pp. 605-611
Author(s):  
Anca Manole ◽  
Cristian Banciu
Keyword(s):  
Endangered Plant ◽  
Seed Length ◽  
Maturation Period ◽  
Morphophysiological Dormancy ◽  
Whole Seed ◽  
Air Cavities ◽  
Germination Indices ◽  
Essential Oil Production ◽  
Germination Requirements ◽  
Seed Dormancy And Germination

The phenology of Angelica palustris seeds including maturation, germination requirements, and dormancy class, is still unknown. In opposite to the results reported from other species of Angelica, present findings showed that A. palustris produced seeds with embryo underdeveloped (the ratio between the embryo and the whole seed length was between 0.19 and 0.12) and physiologically dormant which corresponded to Morphophysiological Dormancy class. Dormancy breakdown requires a post maturation period (at least 30 days) at 18 - 20ºC for a complete embryo development, and also up to 30 days of cold stratification at 4°C. The best germination indices were obtained when fruit was removed. Germination energy (Ge) was achieved within 19 days after imbibition and was 25.8 + 0.03 and germination per cent (Gp) was achieved within 28 days and was 64.7 + 0.14. Fruit structure (lateral wings with air cavities) and physiology (essential oil production) are adaptations to facilitate seed dispersal and dormancy/germination balance.

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