Is it time to retire the CTDI for CT quality assurance and dose optimization?

Brenner, David J.

doi:10.1118/1.2040747

Cited by 48 publications

(28 citation statements)

References 24 publications

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“…Conversely, the head CTDI phantom is only

~ 90 %

of the volume of RANDO's head, so the nominal

{CTDI}_{w}

is a much better estimate of the absorbed dose. This confirms previous reports that the

{CTDI}_{w}

is not adequate to estimate the patient‐specific absorbed dose 20 , 21 , 22 . Additionally, despite the fact that the nominal value of the

{CTDI}_{w}

in the head falls within the same order of magnitude as measured doses in the anthropomorphic phantom, it fails to account for the large (

0.07 - 0.49 cGy

) dose variations throughout the volume.…”

Section: Discussionsupporting

confidence: 83%

Experimental validation of a kV source model and dose computation method for CBCT imaging in an anthropomorphic phantom

Poirier¹,

Tambasco

2016

J Applied Clin Med Phys

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We present an experimental validation of a kilovoltage (kV) X‐ray source characterization model in an anthropomorphic phantom to estimate patient‐specific absorbed dose from kV cone‐beam computed tomography (CBCT) imaging procedures and compare these doses to nominal weighted CT‐dose index (CTDIw) dose estimates. We simulated the default Varian on‐board imager 1.4 (OBI) default CBCT imaging protocols (i.e., standard‐dose head, low‐dose thorax, pelvis, and pelvis spotlight) using our previously developed and easy to implement X‐ray point‐source model and source characterization approach. We used this characterized source model to compute absorbed dose in homogeneous and anthropomorphic phantoms using our previously validated in‐house kV dose computation software (kVDoseCalc). We compared these computed absorbed doses to doses derived from ionization chamber measurements acquired at several points in a homogeneous cylindrical phantom and from thermoluminescent detectors (TLDs) placed in the anthropomorphic phantom. In the homogeneous cylindrical phantom, computed values of absorbed dose relative to the center of the phantom agreed with measured values within ≤2% of local dose, except in regions of high‐dose gradient where the distance to agreement (DTA) was 2 mm. The computed absorbed dose in the anthropomorphic phantom generally agreed with TLD measurements, with an average percent dose difference ranging from 2.4%±6.0% to 5.7%±10.3%, depending on the characterized CBCT imaging protocol. The low‐dose thorax and the standard dose scans showed the best and worst agreement, respectively. Our results also broadly agree with published values, which are approximately twice as high as the nominal CTDIw would suggest. The results demonstrate that our previously developed method for modeling and characterizing a kV X‐ray source could be used to accurately assess patient‐specific absorbed dose from kV CBCT procedures within reasonable accuracy, and serve as further evidence that existing CTDIw assessments underestimate absorbed dose delivered to patients.PACS number(s): 87.57.Q‐, 87.57.uq, 87.10.Rt

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“…Conversely, the head CTDI phantom is only

~ 90 %

of the volume of RANDO's head, so the nominal

{CTDI}_{w}

is a much better estimate of the absorbed dose. This confirms previous reports that the

{CTDI}_{w}

is not adequate to estimate the patient‐specific absorbed dose 20 , 21 , 22 . Additionally, despite the fact that the nominal value of the

{CTDI}_{w}

in the head falls within the same order of magnitude as measured doses in the anthropomorphic phantom, it fails to account for the large (

0.07 - 0.49 cGy

) dose variations throughout the volume.…”

Section: Discussionsupporting

confidence: 83%

Experimental validation of a kV source model and dose computation method for CBCT imaging in an anthropomorphic phantom

Poirier¹,

Tambasco

2016

J Applied Clin Med Phys

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“…2 The effective dose estimates are therefore a crude measure of risk at best. 29 Even if the true organ doses are known, calculation of risk is complex as the age-dependent radiation risk to each organ is different. 30 Furthermore, such calculation assumes linearity of risk at low radiation doses.…”

Section: Discussionmentioning

confidence: 99%

Radiation doses to emergency department patients undergoing computed tomography

Worrall¹,

Jama²,

Stiell

2014

CJEM

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Objectives: Computed tomography (CT) use is increasing in the emergency department (ED). Many physicians are concerned about exposing patients to radiation from CT scanning, but estimates of radiation doses vary. This study's objective was to determine the radiation doses from CT scanning for common indications in a Canadian ED using modern multidetector CT scanners. Methods: We conducted a health records review of consecutive adult patients seen at two busy tertiary care EDs over a 2-month period who underwent CT scanning ordered by emergency physicians. Cases were identified by searching an imaging database. Data collected included patient age and sex, study indication, scanner model, body area, and reported dose-length product. Effective dose per scan was calculated from reported dose-length product. Data were collected on a standardized form, entered into an electronic database, and analyzed with descriptive statistics and 95% CIs. Results: During the study period, emergency physicians assessed 19,880 patients. Overall, 2,720 (13.7%) underwent CT scanning, and of these, 144 (5.3%) patients had more than one scan. Patients had a mean age of 59.0 years, and 45.3% were men. Mean doses for the most common indications were as follows: simple head, 2.9 mSv; cervical spine, 5.7 mSv; complex head, 9.3 mSv; CT pulmonary angiogram, 11.2 mSv; abdomen (nontraumatic abdominal pain), 15.4 mSv; and abdomen (renal colic), 9.8 mSv.Conclusions: Approximately one in seven ED patients had a CT scan. Emergency physicians should be aware of typical radiation doses for the studies they order and how the dose varies by protocol and indication. RÉ SUMÉObjectif: Le recours à la tomodensitomé trie (TDM) est à la hausse dans les services d'urgence (SU), et l'exposition des patients au rayonnement des appareils de TDM pré occupe bon nombre de mé decins, mais les estimations des doses sont variables. L'é tude visait à dé terminer les doses de rayonnement é mises par des appareils modernes de TDM à dé tecteurs multiples, utilisé s dans un hô pital, au Canada, dans des indications courantes. Mé thode: Nous avons procé dé à un examen des dossiers mé dicaux d'adultes consé cutifs, qui ont é té examiné s dans deux SU de soins tertiaires, ayant une forte fré quentation, sur une pé riode de 2 mois, et qui ont subi un examen par TDM à la demande d'urgentologues. La recherche de cas s'est faite dans une base de donné es d'images. La collecte de donné es comprenait l'âge et le sexe des patients, les indications de l'examen, le modè le d'appareil, la ré gion du corps, ainsi que le produit dose-longueur indiqué . La dose efficace par balayage a é té calculé e à l'aide de ce produit dose-longueur. Les donné es ont é té recueillies sur un formulaire normalisé , inscrites dans une base de donné es é lectroniques, puis analysé es à l'aide de statistiques descriptives et d'intervalles de confiance à 95%. Ré sultats: Durant la pé riode à l'é tude, 19 880 patients ont é té examiné s par des urgentologues; 2720 (13.7%) d'entre eux ont subi une TDM, ...

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“…While CT Dose Index (CTDI) has been widely used in categorizing radiation doses from CT and CBCT scanners, it is a scanner-dependent index and not directly related to the organ dose in the patient being scanned [4]. On the other hand, modern radiotherapy treatment planning systems (TPS) do not offer CT/CBCT dose calculation capability.…”

Section: Introductionmentioning

confidence: 99%