The impact of margin reduction on radiation dose distribution of ultra-hypofractionated prostate radiotherapy utilizing a 1.5-T MR-Linac.
J Appl Clin Med Phys
; 25(1): e14179, 2024 Jan.
Article
em En
| MEDLINE
| ID: mdl-38013636
ABSTRACT
BACKGROUND:
We examined the effects of reducing the planning target volume (PTV) margin in MR-guided radiotherapy (MRgRT) on the distribution of radiation dose to target volumes and organs-at-risk (OARs). Thus, we compared MR-Linac (MRL) plans with and without reduced margin and intensity-modulated radiotherapy (IMRT) plan with conventional linac for low-risk prostate cancer patients receiving 36.25 Gy in five fractions of ultra-hypofractionated radiation therapy. MATERIALS ANDMETHODS:
Twenty low-risk prostate cancer patients treated with 1.5 T MR-Linac were evaluated. The same planning CT images were used for four plans the MRL-R plan with reduced margin planning target volume (PTV-R) and the MRL-N plan with normal margin PTV (PTV-N), which is also used for IMRT plan. In four plans, PTV doses, organs-at-risk (OARs) doses, the homogeneity index (HI), and monitor units were compared.RESULTS:
All plans met the criteria for PTV coverage and OARs dose constraints. The maximum and mean PTV doses were significantly higher in the MRL-R and MRL-N plans compared to the IMRT plan. The HI was lowest in the IMRT plan (0.040 ± 0.013) and highest in the MRL-N plan (0.055 ± 0.012; p < 0.001). There was no significant difference in the PTV dosimetric parameters between the MRL-R and the MRL-N plans. The high doses in the rectum was significantly lower in the MRL-R compared to other plans. The bladder V36.25 Gy was significantly lower in the MRL-R plan (2.43 ± 1.87 Gy) compared to MRL-N (4.50 ± 2.42 Gy; p < 0.001), and IMRT plans (4.76 ± 2.77 Gy; p < 0.001). There was no significant difference in the low-dose volumes of the body, maximum femur doses, or monitor units across each plan.CONCLUSIONS:
Ultra-hypofractionated MR-guided RT with 1.5 T MRL is dosimetrically feasible for patients with prostate cancer. The improved soft tissue contrast and the online adaptive plan for 1.5 T MR-Linac allows for PTV margin reduction resulted in a significant dose reduction in OARs.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Temas:
Geral
/
Prevencao_e_fatores_de_risco
/
Agentes_cancerigenos
/
Tipos_de_cancer
/
Outros_tipos
/
Tratamento
/
Radioterapia
Base de dados:
MEDLINE
Assunto principal:
Neoplasias da Próstata
/
Radioterapia de Intensidade Modulada
Limite:
Humans
/
Male
Idioma:
En
Revista:
J Appl Clin Med Phys
Assunto da revista:
BIOFISICA
Ano de publicação:
2024
Tipo de documento:
Article
País de afiliação:
Turquia