Output Measurements of Monte Carlo, Collapse Cone and Pencil Beam Algorithms in Homogeneous and Inhomogeneous Phantom

Yıl 2019, Cilt: 5 Sayı: 2, 251 - 260, 19.12.2019

İsmail Faruk Durmuş , Emine Dilara Atalay

https://doi.org/10.28979/comufbed.548329

Cited By: 1

Öz

Accuracy of small
field measurements and calculation algorithms is critical for accurate
calculation of dose distribution in Radiotherapy. In inhomogeneous and
homogeneous phantoms, measurements (1x1, 2x2, 3x3, 4x4, 5x5cm² field
sizes) were made with CC04 and CC01 Razor ion chambers using 6MV, 6MV-FFF, 10MV
and 10MV-FFF energies. In the Monaco treatment planning system, dose
distribution was calculated by Monte Carlo-Dose to Medium (MC-Dm), Monte
Carlo-Dose to Water (MC-Dw), Collapse Cone (CC) and Pencil Beam (PB) algorithms
and compared with measurements. The homogeneous phantom water equivalent was
generated from RW3 solid phantoms, and the inhomogeneous phantom was created
using a water-equivalent RW3 solid phantom and a lung equivalent balsa phantom.
When both the homogeneous and inhomogeneous phantom measurements were evaluated
with CC04 and CC01Razor ion chambers, results consistent with MC-Dm, MC-Dw, CC
and PB were obtained. The greatest differences in both phantoms were obtained
in 1x1cm² fields. When the results in the inhomogeneous phantom were
compared with the results in the homogeneous phantom, the compliance ratio was
observed to be better in the homogeneous phantom. The CC01 Razor ion chamber
has a volume of 0.01cm³ and its central electrode is graphite. With
the CC01 Razor ion chamber, reliable results were obtained. As the field size
becomes smaller, the differences between measurements and calculations increase.

Anahtar Kelimeler

Inhomogeneity, Monte Carlo, CC01 Razor ion chamber

Monte Carlo, Collapse Cone ve Pencil Beam Algoritmalarının Homojen ve İnhomojen Fantomda Açık Alan Ölçümleri

Öz

Radyoterapide doz
dağılımının doğru hesaplanması için küçük alan ölçümleri ve hesaplama
algoritmalarının doğruluğu kritik öneme sahiptir. İnhomojen ortamlarda küçük
alan dozimetrisindeki belirsizlikler ve zorluklar daha da artmaktadır. Bu
çalışmada inhomojen ve homojen fantomlarda 6MV, 6MV-FFF, 10MV ve 10MV-FFF
enerjileri ile 1x1, 2x2, 3x3, 4x4, 5x5cm² alan boyutlarında CC04 ve
CC01 Razor iyon odaları ile ölçümler alındı. Ölçümler ile Monaco tedavi
planlama sisteminde Monte Carlo-Dose to Medium (MC-Dm), Monte Carlo-Dose to
Water (MC-Dw), Collapse Cone (CC) ve Pencil Beam (PB) algoritmaları ile yapılan
hesaplamalar karşılaştırıldı. Homojen fantom su eşdeğeri RW3 katı
fantomlardan,  inhomojen fantom ise su
eşdeğeri RW3 katı fantom ve akciğer eşdeğeri balsa fantom kullanılarak
oluşturuldu. CC04 ve CC01 Razor iyon odaları ile hem homojen hem de inhomojen
fantomda ölçümler değerlendirildiğinde, MC-Dm, MC-Dw, CC ve PB ile uyumlu
sonuçlar elde edildi. Her iki fantomda da en büyük farklar 1x1cm²
alanlarda olduğu görüldü. İnhomojen fantomdaki sonuçlar homojen fantomdaki
sonuçlarla karşılaştırıldığında uyum oranının homojen fantomda daha iyi olduğu
görüldü. CC01 Razor iyon odası 0.01cm³ hacme sahip ve merkezi
elektrodu grafittir. Bu özellikleri ile CC01 Razor iyon odası ile yeterince
güvenilir sonuçlar elde edilmiştir. Alan boyutu küçüldükçe ölçümler ve
hesaplamalar arasındaki farklar artmaktadır.

Anahtar Kelimeler

İnhomojenite, Monte Carlo, CC01 Razor İyon Odası

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