Dose to Radiosensitive Organs During Routine Chest CT: Effects of Tube Current Modulation

Angel, Erin; Yaghmai, Nazanin; Jude, Cecilia Matilda; DeMarco, John J.; Cagnon, Christopher H.; Goldin, Jonathan G.; McCollough, Cynthia H.; Primak, Andrew N.; Cody, Dianna D.; Stevens, David B.; McNitt‐Gray, Michael F.

doi:10.2214/ajr.09.2886

Cited by 77 publications

(57 citation statements)

References 24 publications

(39 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Additionally, investigations into the effects of tube current modulation ͑TCM͒ are underway. TCM is used routinely in abdominal scans 23,24 and, depending on the type of TCM used, the scheme may adjust the tube current for patient size as well as modulate along the z-axis and within the x-y plane. Therefore, techniques to account for TCM similar to those described by Angel et al 14,24 will be investigated.…”

Section: Discussionmentioning

confidence: 99%

The feasibility of patient size‐corrected, scanner‐independent organ dose estimates for abdominal CT exams

et al. 2011

Self Cite

View full text Add to dashboard Cite

Purpose:A recent work has demonstrated the feasibility of estimating the dose to individual organs from multidetector CT exams using patient-specific, scanner-independent CTDI vol -to-organ-dose conversion coefficients. However, the previous study only investigated organ dose to a single patient model from a full-body helical CT scan. The purpose of this work was to extend the validity of this dose estimation technique to patients of any size undergoing a common clinical exam. This was done by determining the influence of patient size on organ dose conversion coefficients generated for typical abdominal CT exams. Methods: Monte Carlo simulations of abdominal exams were performed using models of 64-slice MDCT scanners from each of the four major manufacturers to obtain dose to radiosensitive organs for eight patient models of varying size, age, and gender. The scanner-specific organ doses were normalized by corresponding CTDI vol values and averaged across scanners to obtain scannerindependent CTDI vol -to-organ-dose conversion coefficients for each patient model. In order to obtain a metric for patient size, the outer perimeter of each patient was measured at the central slice of the abdominal scan region. Then, the relationship between CTDI vol -to-organ-dose conversion coefficients and patient perimeter was investigated for organs that were directly irradiated by the abdominal scan. These included organs that were either completely ͑"fully irradiated"͒ or partly ͑"partially irradiated"͒ contained within the abdominal exam region. Finally, dose to organs that were not at all contained within the scan region ͑"nonirradiated"͒ were compared to the doses delivered to fully irradiated organs. Results: CTDI vol -to-organ-dose conversion coefficients for fully irradiated abdominal organs had a strong exponential correlation with patient perimeter. Conversely, partially irradiated organs did not have a strong dependence on patient perimeter. In almost all cases, the doses delivered to nonirradiated organs were less than 5%, on average across patient models, of the mean dose of the fully irradiated organs. Conclusions: This work demonstrates the feasibility of calculating patient-specific, scannerindependent CTDI vol -to-organ-dose conversion coefficients for fully irradiated organs in patients undergoing typical abdominal CT exams. A method to calculate patient-specific, scanner-specific, and exam-specific organ dose estimates that requires only knowledge of the CTDI vol for the scan protocol and the patient's perimeter is thus possible. This method will have to be extended in future 820 820 Med. Phys. 38 "2…,

show abstract

Section: Discussionmentioning

confidence: 99%

The feasibility of patient size‐corrected, scanner‐independent organ dose estimates for abdominal CT exams

et al. 2011

Self Cite

View full text Add to dashboard Cite

show abstract

“…Facilities that adjust their CT technique appropriately for patient size, whether with use of manual technique charts or automatic exposure control ( 35,(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53)(54)(55)(56), will prescribe a wide range of scanner output (CTDI) values. This is a good outcome, refl ecting the facility's conscientiousness in "right-sizing" the dose settings on the basis of specifi c patient body habitus.…”

Section: Editorial: Ct Dose Index and Patient Dosementioning

confidence: 99%

CT Dose Index and Patient Dose: They AreNotthe Same Thing

et al. 2011

Self Cite

View full text Add to dashboard Cite

“…[6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] The human body lying on a CT scanner table and helical fan beam x-ray generated from a CT scanner are fully simulated in the computer using the Monte Carlo method.…”

Section: Introductionmentioning

confidence: 99%

Organ doses for reference adult male and female undergoing computed tomography estimated by Monte Carlo simulations

et al. 2011

View full text Add to dashboard Cite

Purpose: To develop a computed tomography ͑CT͒ organ dose estimation method designed to readily provide organ doses in a reference adult male and female for different scan ranges to investigate the degree to which existing commercial programs can reasonably match organ doses defined in these more anatomically realistic adult hybrid phantoms Methods: The x-ray fan beam in the SOMATOM Sensation 16 multidetector CT scanner was simulated within the Monte Carlo radiation transport code MCNPX2.6. The simulated CT scanner model was validated through comparison with experimentally measured lateral free-in-air dose profiles and computed tomography dose index ͑CTDI͒ values. The reference adult male and female hybrid phantoms were coupled with the established CT scanner model following arm removal to simulate clinical head and other body region scans. A set of organ dose matrices were calculated for a series of consecutive axial scans ranging from the top of the head to the bottom of the phantoms with a beam thickness of 10 mm and the tube potentials of 80, 100, and 120 kVp. The organ doses for head, chest, and abdomen/pelvis examinations were calculated based on the organ dose matrices and compared to those obtained from two commercial programs, CT-EXPO and CTDOSIMETRY. Organ dose calculations were repeated for an adult stylized phantom by using the same simulation method used for the adult hybrid phantom. Results: Comparisons of both lateral free-in-air dose profiles and CTDI values through experimental measurement with the Monte Carlo simulations showed good agreement to within 9%. Organ doses for head, chest, and abdomen/pelvis scans reported in the commercial programs exceeded those from the Monte Carlo calculations in both the hybrid and stylized phantoms in this study, sometimes by orders of magnitude. Conclusions: The organ dose estimation method and dose matrices established in this study readily provides organ doses for a reference adult male and female for different CT scan ranges and technical parameters. Organ doses from existing commercial programs do not reasonably match organ doses calculated for the hybrid phantoms due to differences in phantom anatomy, as well as differences in organ dose scaling parameters. The organ dose matrices developed in this study will be extended to cover different technical parameters, CT scanner models, and various age groups.

show abstract

Dose to Radiosensitive Organs During Routine Chest CT: Effects of Tube Current Modulation

Cited by 77 publications

References 24 publications

The feasibility of patient size‐corrected, scanner‐independent organ dose estimates for abdominal CT exams

The feasibility of patient size‐corrected, scanner‐independent organ dose estimates for abdominal CT exams

CT Dose Index and Patient Dose: They AreNotthe Same Thing

Organ doses for reference adult male and female undergoing computed tomography estimated by Monte Carlo simulations

Contact Info

Product

Resources

About