Influence to dosimetry of patient by set-up errors
10.7687/j.issn1003-8868.2017.07.089
- VernacularTitle:摆位误差对患者剂量学的影响
- Author:
Jie HU
1
;
qing Xiao DONG
;
Qing LIN
;
Ying ZHANG
;
fei Jia ZHANG
;
Ying ZHANG
Author Information
1. 上海市第十人民医院放疗科
- Keywords:
rectal cancer;
set-up error;
dosimetry;
dose distribution;
intensity modulated radiationtherapy;
treatment planning system
- From:
Chinese Medical Equipment Journal
2017;38(7):89-92
- CountryChina
- Language:Chinese
-
Abstract:
Objective To investigate the influence to dosimetry of the patient with rectum cancer by setup errors.Methods First an intensity modulated radiation treatment planning for a rectum cancer patient was designed,then the isocenter was moved 5 mm respectively to the left side,right side,abdomen side,back side,head side and foot side;and the isocenter was moved 5 mm to head side,back side and left side at the same time;and the isocenter was moved 5 mm to foot side,abdomen side and right side at the same time;and the isocenter was moved according to the largest set-up error for the first five Cone Beam CT scanning,thus nine new plans and a confirmed plan were got,the influence to dosimetry for targets and fermur head,bladder and intestine for these ten plans was analyzed.Results The influence to the dosimetry gained the maximum value in the planning target volume (PTV) with the isocenter moving 5 mm to three directions and normal organs.All the plans had little influence on clinical target volume (CTV),which posed few effects on small intestine and bladder while big influence to femoral head incase of high dose D2 to 2％ target volume and mean dose.Conclusion The set-up error may influence dosimetry of PTV,and the reduction of low dose D98 to 98％ target volume may affect treatment effect.For patients whose set-up errors are large,times of cone beam CT scanning have to be increased in order to ensure the precise implementation of the treatment plans.
