Evaluation of therapeutic dose linear accelerator out-of-field using different techniques radiation

Prilikom puštanja u rad terapijskog linearnog akceleratora dozimetrijska mjerenja se rade samo u zračnom polju i ti podaci se unose u TPS (sistem za planiranje), dok dozimetrijski podaci izvan zračnog polja nisu dobro dokumentovani. Neminovno je da dijelovi tijela izvan zračnog polja budu izloženi određenoj dozi zračenja rasijanog u tijelu pacijenta, akceleratorskoj glavi, kao i u samoj prostoriji. Razvojem tehnika isporuke doze pomoću kojih imamo mnogo bolju konformalnost, ali isto tako imamo više monitorskih jedinica čime se produžava vrijeme tretmana, a samim time izloženost tijela nižim dozama zračenja. Takođe, koristimo više polja pod različitim uglovima (IMRT) ili puni luk (VMAT). Sve ovo utiče da veća zapremina normalnog tkiva bude izložena nižim dozama zračenja. Cilj ovog rada je da se procijeni vrijednost doze izvan zračnog polja za tretmanske planove (3DCRT, IMRT i VMAT) napravljenih u Eclipse 13.6 TPS (Varian Medical Systems) koja je isporučena pomoću Clinac DHX (Varian Medical Systems) linearnog akceleratora. Mjerenje je rađeno u Thorax Phantom-u (CIRS) pomoću jonizacione komore na udaljenosti od ivice polja u rasponu od 1,75–15,75 cm.When commissioning therapeutic linear accelerator dosimetric measurements are made only in the air field and these data are entered in TPS (treatment planning system), and dosimetry data out-of-field are not well documented. It is inevitable that parts of the body out-of-field to be exposed to a certain dose of the scatter radiation in the patient's body, accelerator head, as well as in the room. The development of technique delivery doses with which we have a much better conformity, but also we have more of monitor units that serve to prolong the treatment time, and thus the exposure of the body lower doses of radiation. Also, use more fields at different angles (IMRT) or full arch (VMAT). All this affects the larger volume of normal tissue is exposed to lower doses of radiation. The aim of this study is to assess the value out-of-field dose for treatment plans (3DCRT, IMRT and VMAT) made in Eclipse 13.6 TPS (Varian Medical Systems) that is delivered using CLINAC DHX (Varian Medical Systems) linear accelerator. Measurement was conducted in Thorax Phantom-in (CIRS) using ionization chamber at the distance from the edge of the field in the range of (1.75 - 15.75) cm

Evaluation of therapeutic dose linear accelerator out-of-field using different techniques radiation

Prilikom puštanja u rad terapijskog linearnog akceleratora dozimetrijska mjerenja se rade samo u zračnom polju i ti podaci se unose u TPS (sistem za planiranje), dok dozimetrijski podaci izvan zračnog polja nisu dobro dokumentovani. Neminovno je da dijelovi tijela izvan zračnog polja budu izloženi određenoj dozi zračenja rasijanog u tijelu pacijenta, akceleratorskoj glavi, kao i u samoj prostoriji. Razvojem tehnika isporuke doze pomoću kojih imamo mnogo bolju konformalnost, ali isto tako imamo više monitorskih jedinica čime se produžava vrijeme tretmana, a samim time izloženost tijela nižim dozama zračenja. Takođe, koristimo više polja pod različitim uglovima (IMRT) ili puni luk (VMAT). Sve ovo utiče da veća zapremina normalnog tkiva bude izložena nižim dozama zračenja. Cilj ovog rada je da se procijeni vrijednost doze izvan zračnog polja za tretmanske planove (3DCRT, IMRT i VMAT) napravljenih u Eclipse 13.6 TPS (Varian Medical Systems) koja je isporučena pomoću Clinac DHX (Varian Medical Systems) linearnog akceleratora. Mjerenje je rađeno u Thorax Phantom-u (CIRS) pomoću jonizacione komore na udaljenosti od ivice polja u rasponu od 1,75–15,75 cm.When commissioning therapeutic linear accelerator dosimetric measurements are made only in the air field and these data are entered in TPS (treatment planning system), and dosimetry data out-of-field are not well documented. It is inevitable that parts of the body out-of-field to be exposed to a certain dose of the scatter radiation in the patient's body, accelerator head, as well as in the room. The development of technique delivery doses with which we have a much better conformity, but also we have more of monitor units that serve to prolong the treatment time, and thus the exposure of the body lower doses of radiation. Also, use more fields at different angles (IMRT) or full arch (VMAT). All this affects the larger volume of normal tissue is exposed to lower doses of radiation. The aim of this study is to assess the value out-of-field dose for treatment plans (3DCRT, IMRT and VMAT) made in Eclipse 13.6 TPS (Varian Medical Systems) that is delivered using CLINAC DHX (Varian Medical Systems) linear accelerator. Measurement was conducted in Thorax Phantom-in (CIRS) using ionization chamber at the distance from the edge of the field in the range of (1.75 - 15.75) cm

Prirodni i proizvedeni radionuklidi u uzorcima mahovina iz regiona Severne Grčke

Terrestrial mosses obtain most of their nutrients directly from precipitation and dry deposition, and they can be used for monitoring of airborne radionuclide depositions. Ninetyfive samples of Hypnum Cupressiforme were collected in Northern Greece during the end of summer 2016. After the preparation, mosses were measured in a low-background HPGe detector with relative efficiency 32%. The activity concentrations of 7 Be ranged from 69 to 1280 Bq kg-1, and the concentrations of 137Cs ranged from 0 to 425 Bq kg-1. The concentrations of 210Pb were between 147 and 1920 Bq kg-1 and for 40K were between 120 and 750 Bq kg-1. Differences have been observed in the activity concentrations between the mosses collected from ground surface, rocks, branches and near roots. Finally, no correlation between the concentrations of 7 Be and 210Pb has been found.Mahovine svoje nutrijente direktno dobijaju iz padavina i suvom depozicijom i mogu se koristiti za monitoring depozicije radionuklida iz vazduha. Devedesetpet uzoraka mahovina (Hypnum Cupressiforme) je sakupljeno u regionu Severne Grčke tokom kraja leta 2016. godine. Posle pripreme, mahovine su merene na niskofonskom HPGe detektoru relativne efikasnosti 32%. Izmerene koncentracije aktivnosti 7 Be su bile od 69 do 1280 Bq kg-1, aktivnosti 137Cs od 0 do 425 Bq kg-1, aktivnosti 210Pb od 147 do 1920 Bq kg-1 , a 40K od 120 do 750 Bq kg-1. Primećene su razlike u koncentracijama aktivnosti radionuklida u mahovinama koje su sakupljene sa zemlje, kamena, grana stabala i blizu korena stabla. Između 7 Be i 210Pb nije pronađena nikakva korelacija