Adult abdomen–pelvis CT: Does equilibrium dose‐pitch product better account for the kVp dependence of organ dose than conventional CTDI?

The aim of this study is to investigate the impact of CT acquisition parameter setting on organ dose and its influence on image quality metrics in pediatric phantom during CT examination. The study was performed on 64-slice multidetector CT scanner (MDCT) Siemens Definition AS (Siemens Sector Healthcare, Forchheim, Germany) using various CT CAP protocols (P1–P9). Tube potential for P1, P2, and P3 protocols were fixed at 100 kVp while P4, P5, and P6 were fixed at 80 kVp with used of various reference noise values. P7, P8, and P9 were the modification of P1 with changes on slice collimation, pitch factor, and tube current modulation (TCM), respectively. TLD-100 chips were inserted into the phantom slab number 7, 9, 10, 12, 13, and 14 to represent thyroid, lung, liver, stomach, gonads, and skin, respectively. The image quality metrics, signal to noise ratio (SNR) and contrast to noise ratio (CNR) values were obtained from the CT console. As a result, this study indicates a potential reduction in the absorbed dose up to 20% to 50% along with reducing tube voltage, tube current, and increasing the slice collimation. There is no significant difference (p > 0.05) observed between the protocols and image metrics.

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Organ Dose Estimates for Hyperthyroid Patients Treated with 131I: An Update of the Thyrotoxicosis Follow-Up Study

Radiation Research ◽

10.1667/rr14160.1 ◽

2015 ◽

Vol 184 (6) ◽

pp. 595 ◽

Cited By ~ 14

Author(s):

Dunstana R. Melo ◽

Aaron B. Brill ◽

Pat Zanzonico ◽

Paolo Vicini ◽

Brian Moroz ◽

...

Keyword(s):

Organ Dose ◽

Follow Up Study ◽

Hyperthyroid Patients

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The validation of organ dose calculations using voxel phantoms and Monte Carlo methods applied to point and water immersion sources

Radiation Protection Dosimetry ◽

10.1093/rpd/nch002 ◽

2004 ◽

Vol 108 (1) ◽

pp. 85-89 ◽

Cited By ~ 16

Author(s):

J. G. Hunt

Keyword(s):

Monte Carlo ◽

Monte Carlo Methods ◽

Water Immersion ◽

Organ Dose ◽

Dose Calculations ◽

Voxel Phantoms

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Evaluation of deformable image registration (DIR) methods for dose accumulation in nasopharyngeal cancer patients during radiotherapy

Radiology and Oncology ◽

10.1515/raon-2017-0033 ◽

2017 ◽

Vol 51 (4) ◽

pp. 438-446 ◽

Cited By ~ 5

Author(s):

Wannapha Nobnop ◽

Imjai Chitapanarux ◽

Hudsaleark Neamin ◽

Somsak Wanwilairat ◽

Vicharn Lorvidhaya ◽

...

Keyword(s):

Spinal Cord ◽

Image Registration ◽

Treatment Plan ◽

Nasopharyngeal Cancer ◽

Treatment Strategies ◽

Deformable Image Registration ◽

Organ Dose ◽

Target Dose ◽

Dose Accumulation ◽

The Impact

Abstract Introduction Deformable image registration (DIR) is used to modify structures according to anatomical changes for observing the dosimetric effect. In this study, megavoltage computed tomography (MVCT) images were used to generate cumulative doses for nasopharyngeal cancer (NPC) patients by various DIR methods. The performance of the multiple DIR methods was analysed, and the impact of dose accumulation was assessed. Patients and methods The study consisted of five NPC patients treated with a helical tomotherapy unit. The weekly MVCT images at the 1st, 6th, 11th, 16th, 21st, 26th, and 31st fractions were used to assess the dose accumulation by the four DIR methods. The cumulative dose deviations from the initial treatment plan were analysed, and correlations of these variations with the anatomic changes and DIR methods were explored. Results The target dose received a slightly different result from the initial plan at the end of the treatment. The organ dose differences increased as the treatment progressed to 6.8% (range: 2.2 to 10.9%), 15.2% (range: -1.7 to 36.3%), and 6.4% (range: -1.6 to 13.2%) for the right parotid, the left parotid, and the spinal cord, respectively. The mean uncertainty values to estimate the accumulated doses for all the DIR methods were 0.21 ± 0.11 Gy (target dose), 1.99 ± 0.76 Gy (right parotid), 1.19 ± 0.24 Gy (left parotid), and 0.41 ± 0.04 Gy (spinal cord). Conclusions Accuracy of the DIR methods affects the estimation of dose accumulation on both the target dose and the organ dose. The DIR methods provide an adequate dose estimation technique for observation as a result of inter-fractional anatomic changes and are beneficial for adaptive treatment strategies.

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