Dose length product

To compare exposure between different CT protocols, one can use the absorbed dose, usually reported as the CT dose index (CTDI) in mGy. This concept was introduced by Jucius and Kambic to predict the multiple slice average dose at the center of a set of axial scans [35], The product of the CTDI j and the z-axis coverage for the particular scan then yields the dose-length product (DLP), where CTDI j is the average dose in the standard head CT dosimetry phantom [36, 37],... 

CTDlvol volumetric CT dose index DLP dose length product... 

The dosimetric quantities typically used in CT are the CT dose index (CTDI) and the dose length product (DLP). The CTDI is defined for an axial CT scan (one rotation of the X-ray tube) by dividing the integral of the absorbed dose along the z axis by the nominal beam width. As shown in Fig. 4.2, this value is equivalent to the dose within the nominal width of the slice assuming that the absorbed dose has a rectangular profile with a constant dose inside the nominal width and zero dose outside. 

A better representation of the overall energy delivered by a given scan protocol is the dose-length product (DTP) that is the volume CTDI multiplied with the total scan length, Uot ... 

Table 4.3. Normalized effective dose per dose-length product (DLP) for adults (standard physique) for various body regions (ICRP 2007b)...

In order to quantify dose exposure for the individual patient, most scanner consoles offer an estimated value prior to the initiation of the scan and after completion present an accumulated value for the examination. Values used on scanner consoles are not displayed in familiar effective dose values but rather encrypted in a dose length product (DLP). But the DLP value can easily be converted to famihar effective dose values by simple multiphcation with a k factor. The k factor used to estimate the effective dose in cardiac CT is that used for the chest CT, 0.017mSv/mGy-cm (Bongartz et al. 1999). Other k factors apply to different body regions. 

Protocol Kilovolt peak (Current rc Icrcncc mAs. actual mAs Dose mo d Lila tion (iollimation (mm X slice no.) Section ihiekncm reconstruction slice interval imm inm) Dose length product (mCjv X cm) l.llcctivc dose (mSv)... 

Clinically, GM-CSF or G-CSF have been used to accelerate recovery after chemotherapy and total body or extended field irradiation, situations that cause neutropenia and decreased platelets, and possibly lead to fatal septic infection or diffuse hemorrhage, respectively. G-CSF and GM-CSF reproducibly decrease the period of granulocytopenia, the number of infectious episodes, and the length of hospitalization in such patients (152), although it is not clear that dose escalation of the cytotoxic agent and increased cure rate can be rehably achieved. One aspect of the effects of G-CSF and GM-CSF is that these agents can activate mature cells to function more efficiently. This may, however, also lead to the production of cytokines, such as TNF- a, that have some toxic side effects. In general, both cytokines are reasonably well tolerated. The side effect profile of G-CSF is more favorable than that of GM-CSF. Medullary bone pain is the only common toxicity. 

In pharmaceutical and medical device development, clinical trials are classified into four main phases designated with Roman numerals 1,11, III and lY The various phases of development trials differ in purpose, length and number of subjects involved. Phase I trials are conducted to determine safe dose levels of a medication, treatment or product (National Institutes of Health, 2002). The main purpose is often to determine an acceptable single dosage - how much can be given without causing serious side-effects. Phase I trials will also involve studies of metabolism and bioavailabity (Pocock, 1983). The sample size of a Phase 1 clinical trial is usually small, ranging from 10-80 subjects (National Institutes of Health, 2002 Pocock, 1983). 

Additional evidence came from the finding that sex pheromone production could be stimulated in male houseflies that do not normally produce detectable sex pheromone components. Male houseflies were found to have longer chain alkenes, Z9-27 H,but did not have Z9-23 H. Implantation of ovaries into male houseflies resulted in a change in hydrocarbon biosynthesis such that the longer chain alkenes were not made but rather they produced the shorter chain length Z9-23 H [240]. Likewise, injection of 20-hydroxyecdysone into males induced sex pheromone production in a dose-dependent manner. These studies demonstrated that males possess the biosynthetic capability to produce sex pheromone, but normally do not produce the 20-hydroxyecdysone necessary to induce sex pheromone production. Males became an excellent model in which to study the hormonal regulation of pheromone biosynthesis in the housefly. 

The deposition of ultrafine particles has been measured in replicate hollow casts of the human tracheobronchial tree. The deposition pattern and efficiency are critical determinants of the radiation dose from the short lived decay products of Rn-222. The experimental deposition efficiency for the six airway generations just beyond the trachea was about twice the value calculated if uniform deposition from laminar flow is assumed. The measured deposition was greater at bifurcations than along the airway lengths for 0.2 and 0.15 ym diameter particles ... 

The chain length is therefore adversely afFected by the irradiation dose rate being inversely proportional to its square root. Wagner (1969) lists a large class of unsaturated compounds in which addition reactions can be induced by irradiation. Typical examples involving long chain lengths are for the addends HC1, Cl2, and HBr in ethylene, benzene, toluene, and so on. where the products are telomers or hexachlorides. 

Levonorgestrel implants consist of 6 Silastic capsules each capsule is 2.4 mm in diameter and 34 mm in length and contains 36 mg levonorgestrel. Total administered (implanted) dose is 216 mg. Perform implantation of all 6 capsules during the first 7 days of menses onset. Insertion is subdermal in the mid-portion of the upper arm (see literature included with the product). 

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