Dose evaluation to patients irradiated by 60Co beams, by means of direct measurement on the incident and on the exit surfaces

Rizzotti, A.; Compri, C.; Garusi, G F

doi:10.1016/s0167-8140(85)80036-0

Cited by 52 publications

(9 citation statements)

References 5 publications

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“…These carriers are then swept across the junction by the natural built-in potential and collected by the electrometer, which forms the basis for diode as a radiation detector (3,14). In radiotherapy application, the diode can be used as in vivo dosimeter for patient dose verification and beam data generation of the radiotherapy equipment during commissioning for patient treatment (3,4,(15)(16)(17)(18)(19)(20)(21)(22)(23)(24). A number of diode dosimeters are available commercially such as Veridose (Cardinal Health Management Services, USA), Isorad (Sun Nuclear, USA), T60010 (PTW, Germany), and EDP (Scanditronix Wellhofer, Sweden).…”

Section: Technology In Cancer Research and Treatment Volume 13 Numbermentioning

confidence: 99%

Dosimetric Characteristics of a PIN Diode for Radiotherapy Application

Kumar

Sharma

Philomina

et al. 2014

Technol Cancer Res Treat

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The PIN diode developed by Bhabha Atomic Research Centre (BARC) was modified for its use as a dosimeter in radiation therapy. For this purpose the diode was mounted on a printed circuit board (PCB) and provided with necessary connections so that its response against irradiation can be recorded by a standard radiotherapy electrometer. The dosimetric characteristics of the diode were studied in Co-60 gamma rays as well as high energy X-rays. The measured sensitivity of this PIN diode is 4 nC/cGy which is about ten times higher than some commercial diode dosimeters. The leakage current from the diode is 0.04 nA. The response of the PIN diode is linear in the range of 20-1000 cGy which covers the full range of radiation dose encountered in radiotherapy treatments. The non-linearity of the diode response is 3.5% at 20 cGy and it is less than 1.5% at higher dose values. Its repeatability is within 0.5%.The angular response variation is about 5.6% within 6608 with respect to normal beam incidence. The response of the PIN diode at 6 and 18 MV X-rays varies within 2% with respect to its response at Co-60 gamma rays. The source to surface distance (SSD) dependence of the PIN diode was studied for Co-60 beam. It was found that the response of the diode decreases almost linearly relative to given dose for beams with constant collimator setting but increasing SSD (decreasing dose-rate). Within this study the diode response varied by about 2.5% between the maximum and minimum SSD. The dose-rate dependence of the PIN diode for 6 and 15 MV-rays was studied. The variation in response of diode for both energies in the studied dose range is less than 1%. The field size dependence of the PIN diode response is within 1% with respect to the response of ionisation chamber. These studies indicate that the characteristics of the PIN diode are suitable for use in radiotherapy dosimetry.

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Section: Technology In Cancer Research and Treatment Volume 13 Numbermentioning

confidence: 99%

Dosimetric Characteristics of a PIN Diode for Radiotherapy Application

Kumar

Sharma

Philomina

et al. 2014

Technol Cancer Res Treat

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“…The Rizzotti-Leunen method was used to calculate the dose at isocenter from the measured entrance and exit doses. The method proposed by Rizzotti et al 16 is based on the determination of the exit transmission, defined as the ratio of exit and entrance doses, and the midline transmission, defined as the ratio of the midline and entrance doses. In practice, a set of curves of midline and exit transmission as a function of water equivalent thickness can be generated theoretically from the TPRs, or can be measured with the aid of a proper phantom.…”

Section: In Vivo Dosimetrymentioning

confidence: 99%

Implementation of in vivo Dosimetry with Isorad™ Semiconductor Diodes in Radiotherapy Treatments of the Pelvis

Rodríguez¹,

Abrego²,

Pineda³

2008

Medical Dosimetry

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“…The midline dose can be determined by converting the measured entrance (or exit) dose with the depth dose data, taking the inhomogeneities into account. [19202122] However, the drawbacks of these methods are that additional patient information is required to determine the midline dose, and the measurements and calculations are not completely independent of the treatment planning process. [23] The back-projection approach is a method to derive the midplane dose from the transmission dose data measured with an EPID, without additional patient information, that is, independent of a treatment planning system (TPS).…”

Section: Introductionmentioning

confidence: 99%

Assessment of a 2D electronic portal imaging devices-based dosimetry algorithm for pretreatment and in-vivo midplane dose verification

et al. 2016

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Background:The use of electronic portal imaging devices (EPIDs) is a method for the dosimetric verification of radiotherapy plans, both pretreatment and in vivo. The aim of this study is to test a 2D EPID-based dosimetry algorithm for dose verification of some plans inside a homogenous and anthropomorphic phantom and in vivo as well.Materials and Methods:Dose distributions were reconstructed from EPID images using a 2D EPID dosimetry algorithm inside a homogenous slab phantom for a simple 10 × 10 cm2 box technique, 3D conformal (prostate, head-and-neck, and lung), and intensity-modulated radiation therapy (IMRT) prostate plans inside an anthropomorphic (Alderson) phantom and in the patients (one fraction in vivo) for 3D conformal plans (prostate, head-and-neck and lung).Results:The planned and EPID dose difference at the isocenter, on an average, was 1.7% for pretreatment verification and less than 3% for all in vivo plans, except for head-and-neck, which was 3.6%. The mean γ values for a seven-field prostate IMRT plan delivered to the Alderson phantom varied from 0.28 to 0.65. For 3D conformal plans applied for the Alderson phantom, all γ1% values were within the tolerance level for all plans and in both anteroposterior and posteroanterior (AP-PA) beams.Conclusion:The 2D EPID-based dosimetry algorithm provides an accurate method to verify the dose of a simple 10 × 10 cm2 field, in two dimensions, inside a homogenous slab phantom and an IMRT prostate plan, as well as in 3D conformal plans (prostate, head-and-neck, and lung plans) applied using an anthropomorphic phantom and in vivo. However, further investigation to improve the 2D EPID dosimetry algorithm for a head-and-neck case, is necessary.

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Dose evaluation to patients irradiated by 60Co beams, by means of direct measurement on the incident and on the exit surfaces

Cited by 52 publications

References 5 publications

Dosimetric Characteristics of a PIN Diode for Radiotherapy Application

Dosimetric Characteristics of a PIN Diode for Radiotherapy Application

Implementation of in vivo Dosimetry with Isorad™ Semiconductor Diodes in Radiotherapy Treatments of the Pelvis

Assessment of a 2D electronic portal imaging devices-based dosimetry algorithm for pretreatment and in-vivo midplane dose verification

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