Naslov
Out-of-field dose measurements for radiotherapy of brain tumours in paediatric patients

Autori
Stolarczyk, Liliana ; Majer, Marija ; Adamek, Natalia ; Gora, Elizabetha ; Kabat, Damian ; Knežević, Željka, Liszka, Malgorzata ; Olko, Pavel ; Miljanić, Saveta ; Harrison, Roger

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
ECPM Abstract Book / Paolo Russo - : Elsevier, 2014, E64-e65

Skup
8th European Conference on Medical Physics

Mjesto i datum
Atena, Grčka, 11.09.2014. - 13.09.2014

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
out-of-field dose measurements ; TLD ; RPL ; child phantom study ; radiotherapy ; LAR

Sažetak
It has been known for many years that out-of-field radiation doses to normal tissues may be associated with an increased risk of secondary cancers. Paediatric patients are of particular concern due to their possible longer life expectancy and higher organ radiosensitivities compared with adult patients and higher organ doses because of their smaller body size. The motivation of EURADOS Working group 9 (WG 9) is to assess unwanted, non-target patient doses in radiotherapy. The purpose of this phantom study was to measure out-of-field organ doses using 5 and 10 year-old anthropomorphic phantoms for modern techniques of radiotherapy. The treatment of a spherical brain tumor with a diameter of 6 cm was simulated with 6 MV photon beams for Intensity Modulated Radiotherapy (IMRT) and 3D Conformal Radiotherapy (3D CRT). Radiophotoluminescent (RPL) and thermoluminescent (TL) dosimeters placed in 20 organs were used for dose measurements. For both techniques organ doses decreased with distance from the target volume. 5 year-old phantom doses were on average 30% and 60% higher than doses for the 10 year-old phantom for IMRT and 3D CRT respectively. For example, for IMRT, doses measured with RPL dosimeters (Figure 1) ranged from approximately 32% of the given tumor dose for eyes and dropped rapidly to 0.3% for thyroid and to 0.02% for testes in the case of 10 year-old phantom. For the 5 year-old phantom, doses ranged from approximately 43% of the given tumor dose for eyes and 0.4% for thyroid to 0.035% for testes. Radiation risks of cancer incidence for seven organs (thyroid, lung, breast, liver, stomach, bladder and prostate) in the form of the lifetime attributable risk (LAR) were estimated using BEIR VII model. For IMRT, the highest risk per single fraction (2 Gy in tumour) was estimated for 5 year-old girls (50 and 34 cancers per 105 patients for breast and thyroid respectively). The highest organ risk in the case of boys was for lungs (11 cancers per 105 5 year old patients).

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Kemija

POVEZANOST RADA