Respiratory correlated segment reconstruction algorithm towards four-dimensional radiation therapy using carbon ion beams.
OBJECTIVE
To enhance the precision of treatment planning for tumors which move under respiration, we developed a respiratory-correlated segment reconstruction method (RS) based on the Feldkamp--Davis--Kress algorithm (FDK) which provides high temporal resolution and a high signal-to-noise ratio. We compared full-scan (FS-FDK) and RS-FDK with regard to dose distribution in heavy ion treatment planning.


METHODS
Data acquisition for RS-FDK is done using a respiratory sensing system in cine scan mode with a 256-multi-detector row CT (256-MDCT). To evaluate the accuracy of irradiation of moving tumors, dose distributions with each algorithm were compared in heavy ion treatment planning using beam parameters obtained with FS-FDK.


RESULTS
Images obtained using RS-FDK did not show motion artifacts and visualized the edges of the liver and pulmonary vessels more clearly than those with FS-FDK. The iso-dose distributions for FS-FDK covered the target volume; in contrast, RS-FDK with the beam parameter of FS-FDK image provided an insufficient dose to the target and a considerable dose to normal tissues around it.


CONCLUSIONS
The information provided by RS-FDK improves accuracy in the prescription of dose-to-target volume. Further, RS-FDK allows greater precision in the delivery of radiotherapy, including 4D radiation therapy.
Mori
Shinichiro
S
Radiological Protection Section, National Institute of Radiological Sciences, Chiba-shi, Chiba, Japan. smori1@partners.org
Endo
Masahiro
M
Kohno
Ryosuke
R
Asakura
Hiroshi
H
Kohno
Kazutoshi
K
Yashiro
Tomoyasu
T
Komatsu
Shuhei
S
Kandatsu
Susumu
S
Baba
Masayuki
M
D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002250:Carbon Radioisotopes / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D019047:Phantoms, Imaging; D011857:Radiographic Image Interpretation, Computer-Assisted; D012119:Respiration; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods* / Q000592:standards
D002250:Carbon Radioisotopes