isodose


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Related to isodose: isodose curve

isodose

(ˈaɪsəʊˌdəʊs)
n
(Medicine) med a dose of radiation applied to a part of the body in radiotherapy that is equal to the dose applied to a different part
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The basal dose rate, high dose volume encompassing 150% isodose diameter around source, hot spot and cold spot were evaluated.
The recorded indices included the homogeneity index (HI = D[sub]max/prescribed dose, where D[sub]max was the maximum dose), the conformity index (CI = prescription isodose volume [PIV]/tumor isodose volume [TIV], where PIV is the total isodose-line three-dimensional (3D) volume and TIV is the tumor volume (TV) covered by the isodose volume), the new CI (nCI = TV x planned target volume/TIV), and tumor coverage.
Owing to her empyema and pneumonia, dual antibiotic treatment was commenced including ceftriaxone 100 mg/kg/day as 2 dose intravenous application and vancomycin 40 mg/kg/day as 4 isodose by intravenous infusion.
Furthermore, not all reported doses and fractionations are unequivocal as the amount of PTV coverage, prescription isodose line, and heterogeneity corrections likely varied between studies.
The isodose objective goal for radiotherapy dose delivery was to achieve 95% dose coverage to the ITV, with rapid falloff to an 80% isodose coverage of the PTV.
The pattern of recurrence was analyzed in 21 patients who had locoregional relapse: "in-field" (if >80% of the tumor recurrence resided within the prescription 95% isodose surface) in 20 patients (95%), at RT field margin (if 20-80% of the lesion was inside the 95% isodose surface) in no patients (0%), and "out-field" in one patient (5%).
Radiotherapy was delivered using mixed six-and nine-mega-electron-volt (MeV) energy electrons to 66 Gray (Gy) in 2 Gy fractions (33 fractions) prescribed to the 90% isodose line to five separate lesions on the right and left back, right neck, and right anterior chest wall.
Electrons are commonly dosed to the 90% isodose [16].
45Gy to 5mm of the skin was prescribed such as 100% isodose covered the skin surface and 85% isodose to 5mm below the surface.
Dose distribution is the most direct and important factor influencing the outcome of brachytherapy.[sup][25] A change in radiation dose affects local control of the tumor significantly.[sup][26] The American Brachytherapy Society recommends three steps for the assessment of the quality of implantation of [sup]125I seeds:[sup][27] (i) review distribution of the isodose to offer the most direct assessment of dose coverage; (ii) generate a DVH to obtain volumetric parameters; (iii) determine the CN and HI to evaluate the dosimetric quality of the brachytherapy plan (which may be of value in assessment of the future clinical outcomes).
Plans were normalized to ensure that the 95% isodose adequately covered the PTV and that the dose distribution was such that the minimum dose to 99% of the PTV volume (D99%) was greater than or equal to 95% of the prescribed dose (50, 66 and 70 Gy, respectively) and the mean dose to the CTV was within 0,5 Gy of the prescribed dose.