Dosimetry and Adequacy of CT-based Attenuation Correction for Pediatric PET: Phantom Study

Fahey, Frederic H.; Palmer, Matthew R.; Strauss, Keith J.; Zimmerman, R.E.; Badawi, Ramsey D.; Treves, S. Ted

doi:10.1148/radiol.2431060696

Cited by 95 publications

(61 citation statements)

References 15 publications

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“…If anatomic correlation of the PET image is not necessary, lower tube voltages and currents can be used without degradation of the attenuation-corrected PET images (13). For a discussion of the tradeoffs and motivations for different CT acquisitions in pediatric PET/CT, readers are referred to the work by Gelfand and Lemen (14).…”

Section: Pet/ct Protocol Designmentioning

confidence: 99%

Weight-Based, Low-Dose Pediatric Whole-Body PET/CT Protocols

Alessio¹,

Kinahan²,

Manchanda³

et al. 2009

J Nucl Med

112

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Adult PET/CT acquisition protocols need to be modified for pediatric imaging to minimize the radiation dose while maintaining diagnostic utility. We developed pediatric PET/CT acquisition protocols customized to patient weight and estimated the dosimetry and cancer risk of these low-dose protocols to communicate basic imaging risks. Methods: Protocols were developed for whole-body 18 F-FDG imaging of patients in PET mode with a weight-based injected activity (5.3 MBq/kg) and acquisition times (3-5 min/field of view) and for CT for attenuation correction and localization with a weightbased tube current ranging from 10 to 40 mAs. Patients were categorized on the basis of the Broselow-Luten color-coded weight scale. Dosimetry and radiation-induced cancer risk for the PET and CT acquisition in each category were derived from mean patient sizes and the interpolation of factors from accepted patient models. Results: Whole-body pediatric PET/CT protocols require the customization of PET-acquisition settings and task-specific selection of CT technique. The proposed weight-based protocols result in an approximate effective dose ranging from 8.0 mSv for a 9-kg patient up to 13.5 mSv for a 63-kg patient. The radiation dose from the proposed protocols is 20%250% (depending on patient weight), the dose from PET/ CT protocols that use a fixed CT technique of 120 mAs and 120 kVp. The approximate, conservative estimate of additional lifetime attributable risk (LAR) of cancer incidence for females using the proposed protocols was approximately 3 in 1,000, with a variation of 18% across patient categories. For males, the additional LAR of cancer incidence was approximately 2 in 1,000, with a variation of 16% across categories. Conclusion: Lowdose PET/CT protocols for 11 patient weight categories were developed. The proposed protocols offer an initial set of acquisition parameters for pediatric PET/CT. The use of multiple categories allows for the continued refinement of dose-reduction parameters to minimize dose while maintaining image quality across the range of pediatric patient sizes. Thecombi nation of PETand CT is a well-established tool for adult medical imaging and has proven value for oncology, cardiology, and neurology. As the availability of these dualmodality systems increases, PET/CT is of growing importance in pediatric imaging-particularly for cancer detection, staging, therapeutic response monitoring, and outcome prediction (1). Adult PET/CT protocols should be appropriately modified for application to the pediatric population. Several works have offered recommendations on pediatric PET/CT protocols (2-4). In general, pediatric protocols are similar to adult protocols. Some variations that may require special attention include ensuring that the patient is quiescent during the uptake phase, providing a warm environment during the uptake phase, and determining whether sedation and imaging of the extremities is warranted. Development of pediatric protocols also requires the careful selection of PET and CT acquisition ...

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Section: Pet/ct Protocol Designmentioning

confidence: 99%

Weight-Based, Low-Dose Pediatric Whole-Body PET/CT Protocols

Alessio¹,

Kinahan²,

Manchanda³

et al. 2009

J Nucl Med

112

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“…The survey results reported here indicated that there is considerable variation in the acquisition of the CT component even among dedicated pediatric institutions, which further shows the potential need for standardization. Over the past decade, several groups have reported on the optimization of pediatric PET/CT (25,(41)(42)(43)(44). We have presented the Boston Children's approach as an option that uses AEC to manage radiation dose without setting specific levels for different-sized patients.…”

Section: Discussionmentioning

confidence: 99%

“…In PET/CT, the CT can be used for any of 3 distinct purposesattenuation correction, anatomic colocalization, or Dx interpretationor for a combination of these (21,25). Attenuation correction accounts for differences in the location of positron annihilation events and the degree to which tissues "attenuate" the PET annihilation photons.…”

Section: Acquisition Of Pet/ctmentioning

confidence: 99%

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Operational and Dosimetric Aspects of Pediatric PET/CT

et al. 2017

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Learning Objectives: On successful completion of this activity, participants should be able to (1) list 3 factors that affect CT radiation dose; (2) discuss 3 ways that CT is used in the context of PET/CT; and (3) describe various approaches to integrating PET/CT and diagnostic CT in children.Financial Disclosure: Dr. Fahey is a board member of the American Association of Physicists in Medicine and an employee of Boston Children's Hospital. The authors of this article have indicated no other relevant relationships that could be perceived as a real or apparent conflict of interest. CME Credit: SNMMI is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to sponsor continuing education for physicians. SNMMI designates each JNM continuing education article for a maximum of 2.0 AMA PRA Category 1 Credits. Physicians should claim only credit commensurate with the extent of their participation in the activity. For CE credit, SAM, and other credit types, participants can access this activity through the SNMMI website (http://www.snmmilearningcenter.org) through September 2020.No consistent guidelines exist for the acquisition of a CT scan as part of pediatric PET/CT. Given that children may be more vulnerable to the effects of ionizing radiation, it is necessary to develop methods that provide diagnostic-quality imaging when needed, in the shortest time and with the lowest patient radiation exposure. This article describes the basics of CT dosimetry and PET/CT acquisition in children. We describe the variability in pediatric PET/CT techniques, based on a survey of 19 PET/CT pediatric institutions in North America. The results of the survey demonstrated that, although most institutions used automatic tube current modulation, there remained a large variation of practice, on the order of a factor of 2-3, across sites, pointing to the need for guidelines. We introduce the approach developed at our institution for using a multiseries PET/CT acquisition technique that combines diagnostic-quality CT in the essential portion of the field of view and a low-dose technique to image the remainder of the body. This approach leads to a reduction in radiation dose to the patient while combining the PET and the diagnostic CT into a single acquisition. The standardization of pediatric PET/CT provides an opportunity for a reduction in the radiation dose to these patients while maintaining an appropriate level of diagnostic image quality.

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“…Fahey et al [15] evaluated dosimetry and the combination of both lower CT tube voltage and tube current for adequate CT-based attenuation correction for PET in pediatric patients, and CT acquisition parameters were shown to be adequate for pediatric but not for adult patients. Thus, although the use of a cylindrical phantom (200 mm in diameter and length) and a torso phantom (anteroposterior thickness of 280 mm and lateral thickness of 380 mm) allow to evaluation in patient of normal weight, these results may not be comparable to reported adequate CT tube current in obese patient.…”

Section: Discussionmentioning

confidence: 99%

CT tube current for attenuation map in a combined PET/CT system: obese patient simulated phantom study

2012

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Objective The CT portion of PET/CT provides attenuation correction of the PET emission scan. This study was performed to evaluate how much CT tube current can be lowered while still providing attenuation maps on PET images.Methods Two body phantoms (outside diameters of 300 and 500 mm) were used to investigate and PET/CT acquisitions were performed with an Aquiduo PCA-7000B (Toshiba Medical Systems, Otawara, Japan). The CT scan was performed with the following parameters (120 kVp; 0.5-s rotation; 10, 20, 40, 80, 160, 200, 320, 460 mA).After the CT scan, PET images for 18 F-FDG (5.3 kBq/mL) were obtained for 4 min/bed position. The linear attenuation coefficients for 18 F-FDG in 300-and 500-mm phantoms, the pixel values and SD of CT images, the radioactivity concentration values and the hot-and cold-sphere contrast on PET images in the 500-mm phantom were evaluated. Results ConclusionsAlthough the linear attenuation coefficients in the 300-mm phantom remained the same with varying CT tube current, the 500-mm phantom yielded significant difference in the range 10-40mA. Therefore, the CT tube currents for attenuation correction should be adjusted over 40mA in obese patients.

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Dosimetry and Adequacy of CT-based Attenuation Correction for Pediatric PET: Phantom Study

Cited by 95 publications

References 15 publications

Weight-Based, Low-Dose Pediatric Whole-Body PET/CT Protocols

Weight-Based, Low-Dose Pediatric Whole-Body PET/CT Protocols

Operational and Dosimetric Aspects of Pediatric PET/CT

CT tube current for attenuation map in a combined PET/CT system: obese patient simulated phantom study

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