Impact of gamma analysis parameters on dose evaluation using Gafchromic EBT2 films

Lee, Seu-Ran; Park, Jiyeon; Suh, Tae-Suk; Park, Hae-Jin; Lee, Jeongwoo; Jung, Woo-Hwan

doi:10.3938/jkps.61.1319

Cited by 4 publications

(3 citation statements)

References 20 publications

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“…Volumetric-modulated arc therapy (VMAT) is utilized in clinics because of its enhanced tumor control, low toxicity to the organs at risk, and efficient treatment delivery. (1,2) The enhanced flexibility of VMAT is achieved by applying a continuous modulation of factors such as the gantry speed, dose rate, and dynamic movement of multileaf collimators (MLC) and may yield a highly optimal dose distribution with a small beam delivery time. (3)(4)(5) However, the high modulation of the beam in VMAT can cause a dose discrepancy in the beam delivery because of the disagreement between the planned and actual movements of the machine.…”

Section: Introductionmentioning

confidence: 99%

“…These studies compared various gamma analyses and suggested adequate levels of gamma parameters. (2,3,12,13) The American Association of Physicists in Medicine (AAPM) Task Group 119 (TG-119) evaluated the overall accuracy of planning and delivery of intensity-modulated radiation therapy (IMRT) techniques and produced quantitative confidence limits as a result. The TG-119 instructed facilities to use a low-dose threshold of 10% or a region of interest (ROI) determined by the jaw setting when they collected gamma analysis QA data on planar dose distributions.…”

Section: Introductionmentioning

confidence: 99%

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Gamma analysis dependence on specified low‐dose thresholds for VMAT QA

Song

Kim

Park

et al. 2015

J Applied Clin Med Phys

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The American Association of Physicists in Medicine Task Group 119 instructed institutions to use a low‐dose threshold of 10% or a region of interest determined by the jaw setting when they collected gamma analysis quality assurance (QA) data for the planar dose distribution. However, there are no clinical data to quantitatively demonstrate the impact of the low‐dose threshold on the gamma index. Therefore, we performed a gamma analysis with various low‐dose thresholds in the range of 0% to 15% according to both global and local normalization and different acceptance criteria (3%/3 mm, 2%/2 mm, and 1%/1 mm). A total of 30 treatment plans — 10 head and neck, 10 brain, and 10 prostate cancer cases — were randomly selected from the Varian Eclipse treatment planning system (TPS). For the gamma analysis, a calculated portal image was acquired through a portal dose calculation algorithm in the Eclipse TPS, and a measured portal image was obtained using an electronic portal‐imaging device. Then, the gamma analysis was performed using the Portal Dosimetry software (Varian Medical Systems, Palo Alto, CA). The gamma passing rate (%GP) for the global normalization decreased as the low‐dose threshold increased, and all low‐dose thresholds led to %GP values above 95% for both the 3%/3 mm and 2%/2 mm criteria. However, for the local normalization, %GP for a low‐dose threshold of 10% was 7.47%, 10.23%, and 6.71% greater than the low‐dose threshold of 0% for head and neck, brain, and prostate for the 3%/3 mm criteria, respectively. The results indicate that applying the low‐dose threshold to global normalization does not have a critical impact on patient‐specific QA results. However, in the local normalization, the low‐dose threshold level should be carefully selected because the excluded low‐dose points could cause the average %GP to increase rapidly.PACS number: 87.55.Qr

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Gamma analysis dependence on specified low‐dose thresholds for VMAT QA

Song

Kim

Park

et al. 2015

J Applied Clin Med Phys

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“…In order to meet the requirements in the radiation processing, several dosimeters have been successfully developed and used as routine dosimetry systems for radiation processing, that is, various types of radiochromic plastic films, GafChromic Dosimetry Media, and aqueous solutions . Particularly, radiochromic films have been extensively used for dosimetry in radiation medicine .…”

Section: Introductionmentioning

confidence: 99%

A versatile radiochromic dosimeter for low‐medium gamma radiation and its application to food irradiation

Lopes

Ferreira

Franco

et al. 2017

J of Applied Polymer Sci

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This article presents a novel radiochromic film for selective detection of low-medium (0-10 kGy) gamma radiation ( 60 Co) doses. This dosimeter is based on a printed fluorescent multilayer structure comprising a paper substrate having layers of copper phthalocyanine (DY220) (a green emitter material) on the bottom, and layers of poly[2-methoxy-5(2 0 -ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) (a green-light absorber, red emitter, and radiation sensitive polymer) on the top. The effect of gamma radiation on the optical properties of DY220/MEH-PPV was described: it was observed as a strong correlation between radiation dose and fluorescent, color coordinates for CIE (1931) chromatic diagram, and Pantone color reference of the dosimeter. The rate of these changes can be altered by manipulation of top-bottom layers to represent easily the radiation dose to be determined in a wide range. This versatile dosimeter has many uses in the field of food radiation for monitoring, quality assurance, and control of the gamma radiation process.

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Çoklu Vmat Alanlarinin Kali̇te Güveni̇li̇rli̇ği̇ (Kg) İçi̇n Beli̇rlenen Düşük Doz Eşi̇kleri̇nde Gama Anali̇zi̇ Bağimliliği

Erdoğan

2024

Kocatepe Tıp Dergisi

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AMAÇ: Amerikan Tıp Fizikçileri Derneği (AAPM) TG-119 numaralı raporunda, düzlemsel doz dağılımı gama analizi için kalite güvenilirliği (KG) verilerini değerlendirirken %10'luk düşük doz eşiği veya kolimatör tarafından belirlenen bir değerlendirme alanı kullanılmasını önermektedir. Bu çalışmada, standart ve daha rijit kabul kriterlerine göre (%3/3 mm, %2/2mm ve %1/1mm) %0 ile %15 aralığında çeşitli düşük doz eşiklerinin tedavi planları kalite kontrollerindeki etkisinin incelenmesi amaçlanmıştır. GEREÇ VE YÖNTEM: VarianEclipse® tedavi planlama sisteminden (TPS) 11 baş ve boyun, 11 beyin, 11 akciğer ve 11 prostat kanseri vakası olmak üzere toplam 44 çoklu VMAT (Hacimsel Modülasyonlu Ark Terapi) tedavi planı rastgele seçildi. Daha sonra portal dozimetri yazılımı kullanılarak gama analizleri gerçekleştirildi. BULGULAR: Global normalizasyon kullanımında; gama geçiş oranı (%GP), düşük doz eşiğinin değeri arttıkça azaldı. Kullanılan düşük doz eşiklerin de %3/3 mm ve %2/2 mm kriteri için; akciğer kanseri hariç, %GP değerleri %95'in üzerine çıkmıştır.%GP'deki değişim yüzdesi; düşük doz eşiği %15 için, %3/3mm %2/2mm ve %1/1 mm kriterlerine göre akciğer kanseri planlarında sırasıyla %1.69, %5.65ve %20.03 olarak gözlenmiştir. Lokal gama analizinde, düşük doz eşiği arttıkça %GP artmıştır, bu global gama yönteminin tam tersi bir sonucudur. Tüm vakalarda, %3/3mm ve %5 düşük doz eşiği ve üzeri için %95'in üzerinde çıkmıştır. Lokal gama yönteminde, %GP'deki değişim yüzdesi düşük doz eşiği %15 için %3/3mm %2/2mm ve % 1/1 mmkriterlerine göre akciğer kanseri planlarında sırasıyla %2.98, %7.88ve %23.86 olarak gözlenmiştir. Rijit kabul kriterleri uygulandığında %GP sonucu azalmaya başlamıştır. Hem %2/2mm hem de%1/1mm kriterleri için ortalama GP, tüm düşük doz eşiklerinde %95'in altında bulunmuştur. SONUÇ: Global normalizasyonda, farklı düşük doz eşik seviyesi kullanarak gama analizi uygulamanın, KG sonuçları üzerinde kritik bir etkisinin olmadığını göstermektedir. Lokalnormalizasyonda, düşük doz eşik seviyesi dikkatli seçilmelidir, düşük doz noktaları ortalama %GP'nin hızla artmasına neden olabilmektedir.

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Impact of gamma analysis parameters on dose evaluation using Gafchromic EBT2 films

Cited by 4 publications

References 20 publications

Gamma analysis dependence on specified low‐dose thresholds for VMAT QA

Gamma analysis dependence on specified low‐dose thresholds for VMAT QA

A versatile radiochromic dosimeter for low‐medium gamma radiation and its application to food irradiation

Çoklu Vmat Alanlarinin Kali̇te Güveni̇li̇rli̇ği̇ (Kg) İçi̇n Beli̇rlenen Düşük Doz Eşi̇kleri̇nde Gama Anali̇zi̇ Bağimliliği

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