Avtor/Urednik		Sibata, Claudio H; de Almeida, Carlos E; Shin, Ku
Naslov		Thyroid doses due to stereotactic radiosurgery of the brain
Prevedeni naslov		Obsevalne doze na ščitnico pri stereotaksični radiokirurgiji možgan
Tip		članek
Vir		Radiol Oncol
Vol. in št.		Letnik 32, št. 4
Leto izdaje		1998
Obseg		str. 417-21
Jezik		eng
Abstrakt		Background and purpose. Radiosurgery is an irradiation technique in which one high dose fraction or more is applied to a small intracranial volume stereotactically located. The technique is presently in use at the Roswell Park Cancer Institute and it uses 6 non-coplanar arcs, delivered by a 6 MV photon beam from a linear accelerator. One of the issues discussed in the recent BEIR Report V is the radiogenic aspects of solid tumours and the risks related to external radiation. Thyroid carcinoma has been observed to increase consistently in a number of irradiated populations. The thyroid gland in children under 15 years of age, has one of the highest risk coefficients of any organ and is the only tissue with convincing evidence of risk at about 10 cGy. Since children of different ages may also present clinical situations that requires radiosurgery, an investigation was conducted to assess the to the thyroid and other nearby organs. Materials and methods: In-vivo patient measurements were conducted, using TLDs and diodes at the surface of the patient neck corresponding to the thyroid plane as well as with the Alderson phantom for similar geometry and at 0,6 cm of depth in the same plane. Results: The measured thyroid doses in the order of 10 cGy are essentially independent of cone size since the typical doses used in radiosurgery increases considerably as the cone size decreases. Conclusions: A recommendation is made to eliminate or to displace the treatment arc which projection passes through the thyroid plane. This procedure must be adopted for children under 5 years of age and strongly recommended for children up to 15 years of age.
Izvleček		Izhodišča in namen. Radiokirurgija je obsevalna tehnika, kjer majhen, stereotaktično lokaliziran volumen obsevamo z eno ali več visokodoznimi frakcijami. Roswell park Cancer Institute trenutno uporablja tehniko s 6 nekoplanarnimi loki ter 6 MeV fotonskim linearnim pospeševalnikom. Ena izmed tem, ki so bile nedavno obravnavane v BRIR Report V, je radiogenski nastanek solidnih tumorjev in tveganje, povezano z zunanjim obsevanjem. Opisujejo stalno povečanje ščitničnega raka v številnih obsevalnih populacijah. Ščitnica ima pri otrocih mlajših od 15 let enega najvišjih koeficientov tveganja med vsemi organi in je edino tkivo s prepričljivimi dokazi za tveganje pri dozi 10 cGy. Ker so pri otrocih različnih starosti lahko prisotna tudi klinična stanja, ki zahtevajo radiokirurgijo, smo opravili raziskavo, da bi določili na ščitnico in bližnje organe. Material in metode. Opravili smo meritve na pacientih in vivo, pri čemer smo uporabljali termoluminiscenčni dozimeter (TLD) in diode na površini bolnikovega vratu, ki je ustrezala legi ščitnice, ravno tako pa tudi meritve na Aldersonovem fantomu s podobno geometrijo na globini 0,6 cm v enaki legi. Rezultati: Izmerjene ščitnične doze v velikosti 10 cGy so v osnovi neodvisni od velikosti konusa, ker se značilne doze za zdravljenje arteriovenoznih malformacij povečajo z zmanjševanjem velikosti konusa. Zaključki. Svetujemo eliminiranje ali premik terapevtskega loka, katerega projekcija gre skozi ščitnico. Ta postopek moramo uporabljati pri otrocih do starosti 5 let in jo zelo priporočamo do starosti 15 let.
Deskriptorji		RADIOSURGERY THYROID GLAND THYROID NEOPLASMS ARTERIOVENOUS MALFORMATIONS RADIATION DOSAGE