PMID- 31986511
OWN - NLM
STAT- MEDLINE
DCOM- 20210601
LR  - 20210601
IS  - 1361-6498 (Electronic)
IS  - 0952-4746 (Linking)
VI  - 40
IP  - 2
DP  - 2020 Jun
TI  - A Monte Carlo investigation of dose length product of cone beam computed 
      tomography scans.
PG  - 393-409
LID - 10.1088/1361-6498/ab703c [doi]
AB  - The dose length product (DLP) provides a measurement related to energy imparted 
      from a computed tomography (CT) scan. The DLP is based on the volume-averaged CT 
      dose index (CTDI (vol)), which is designed for fan beams. The aims of this study 
      were to investigate the use of DLP for scans with wide beams used in cone beam CT 
      (DLP (CBCT)) in radiotherapy that would be analogous to the DLP of fan beam scans 
      (DLP (CT)), and to compare the efficiencies of DLP (CT) and DLP (CBCT) in 
      reporting the total energy imparted in patients. A validated Monte Carlo model of 
      a kV imaging system integrated into a Varian TrueBeam linac was employed. The DLP 
      (CT) was assessed by multiplying the CTDI (vol) for a 20 mm fan beam by scan 
      length, and the DLP (CBCT) determined through multiplying the CTDI (vol), 
      estimated for wide beams using a correction factor based on free-in-air 
      measurements, by the beam width. Two scan protocols for head and body were 
      investigated for tube potentials between 80 and 140 kV and a range of scan 
      lengths/widths. Efficiency values were estimated by normalising the DLP (CT) and 
      DLP (CBCT) with respect to the corresponding dose profile integrals (DPIs), which 
      were evaluated within 900 mm long phantoms. The results show that the DLP (CBCT) 
      values were within 1% of those for DLP (CT) of similar length performed on the 
      same system, and the efficiencies decrease with tube potential. However, whereas 
      DLP values for fan beams are approximately proportional to scan length, those for 
      wide beams decrease by  approximately 2% between beam widths of 20 and 320 mm. As a result, 
      while the DLP (CT) efficiency is similar over all scan lengths, that for DLP 
      (CBCT) increases slightly with beam width. The DLP (CT) and DLP (CBCT) 
      underestimated the total energy imparted by comparable amounts with efficiencies 
      within the range of 80-81% and 80-83% for the head scans, and 71-76% and 70-77% 
      for the body scans, respectively. The results indicate that the DLP (CBCT) can be 
      considered as an analogous dose index to the DLP (CT). It could, therefore, be 
      used for quantification of doses from imaging in radiotherapy and provide a 
      valuable tool to aid optimisation.
FAU - Abuhaimed, Abdullah
AU  - Abuhaimed A
AD  - King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia.
FAU - Martin, Colin J
AU  - Martin CJ
LA  - eng
PT  - Journal Article
DEP - 20200127
PL  - England
TA  - J Radiol Prot
JT  - Journal of radiological protection : official journal of the Society for 
      Radiological Protection
JID - 8809257
SB  - IM
MH  - *Cone-Beam Computed Tomography
MH  - Humans
MH  - *Monte Carlo Method
MH  - Phantoms, Imaging
MH  - *Radiation Dosage
EDAT- 2020/01/28 06:00
MHDA- 2021/06/02 06:00
CRDT- 2020/01/28 06:00
PHST- 2020/01/28 06:00 [pubmed]
PHST- 2021/06/02 06:00 [medline]
PHST- 2020/01/28 06:00 [entrez]
AID - 10.1088/1361-6498/ab703c [doi]
PST - ppublish
SO  - J Radiol Prot. 2020 Jun;40(2):393-409. doi: 10.1088/1361-6498/ab703c. Epub 2020 
      Jan 27.