Measurement of neutron equivalent dose in the thyroid, chiasma, and lens for patients undergoing pelvic radiotherapy: A phantom study

Shojaei, Mehdi; Rashedi, S.; Chakoli, Ali Nabipour; Karimi, Amir Hossein; Geraily, Ghazale

doi:10.1016/j.apradiso.2022.110188

Cited by 2 publications

(2 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since the threshold energy for (γ, n) reaction is at least 8 MeV [6], neutron contamination in radiation therapy is of concerns in treatment with high-energy photons (> 10 MV). Recently, many researchers in the field of radiation protection have addressed the role and consequences of unwanted doses to the patient caused by photoneutrons [7][8][9]. Some efforts focused on reducing neutron production in the linac head through optimization of the Bremsstrahlung target [10].…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, it has been shown that for glioma and hepatocellular patients undergoing 18 MV radiotherapy, secondary fatal cancer risk due to neutron contamination can reach 281 and 844 persons per one million persons, respectively [7,9]. For prostate patients undergoing 18 MV radiotherapy, it was reported that the total risk of secondary cancer in eye lenses, thyroid, and chiasma is 870 persons per one million persons [8]. Considering the risks of neutron contamination in radiotherapy, further studies are required to evaluate the level of neutron contamination in new radiotherapy modalities (such as SFGRT).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

How much should you worry about contaminant neutrons in spatially fractionated grid radiation therapy?

et al. 2023

Self Cite

View full text Add to dashboard Cite

Neutron contamination in radiation therapy is of concern in treatment with high-energy photons (> 10 MV). With the development of new radiotherapy modalities such as spatially fractionated grid radiation therapy (SFGRT) or briefly grid radiotherapy, more studies are required to evaluate the risks associated with neutron contamination. In 15 MV SFGRT, high-Z materials such as lead and cerrobend are used as the block on the tray of linear accelerator (linac) which can probably increase the photoneutron production. On the other hand, the high-dose fractions (10–20 Gy) used in SFGRT can induce high neutron contamination. The current study was devoted to addressing these concerns via compression of neutron fluence (Φn) and ambient dose equivalent (Hn*(10)) at the patient table and inside the maze between SFGRT and conventional fractionated radiation therapy (CFRT). The main components of the 15 MV Siemens Primus equipped with different grids and located inside a typical radiotherapy bunker were simulated by the MCNPX® Monte Carlo code. Evidence showed that the material used for grid construction does not significantly increase neutron contamination inside the maze. However, at the end of the maze, neutron contamination in SFGRT is significantly higher than in CFRT. In this regard, a delay time of 15 minutes after SFGRT is recommended for all radiotherapy staff before entering the maze. It can be also concluded that Hn*(10) at the patient table is at least 10 times more pronounced than inside the maze. Therefore, the patient is more at risk of neutrons compared to the staff. The Hn*(10) at the isocenter in SFGRT with grids made of lead and cerrobend was nearly equal to CFRT. Nevertheless, it was dramatically lower than in CFRT by 30% if the brass grid is used. Accordingly, SFGRT with the brass grid is recommended, from radiation protection aspects.

show abstract