Evaluation of current method

Table 4.6 shows the number of BAA cases that radiologists handle in a week. Twenty-eight (78.9%) respondents said that they handle from five to ten cases, and eight (21.1%) respondents said they handle from 10 to 20 cases. The feedback shows that BAA is a part of

Year Of Experience Frequency Percentage (%)

Less than 1 year 5 13.9

2 years to 3 years 29 80.6

4 years to 5 years 2 5.6

More than 5 years 0 0

Total 36 100

Time to become expert Frequency Percentage (%)

About 1 to 2 months 6 16.7

About 2 to 4 months 12 33.3

About 4 to 6 months 12 33.3

About 6 to 12 months 6 16.7

Total 36 100

Table 4.4: Working Experience in BAA

the daily task for the radiologists in UMMC. The specialists in this field should handle at least one BAA case per day.

Berst et al. (2001) stated that there are many reasons for conducting BAA. Table 4.7 shows that in UMMC, the main reasons for using BAA are for diagnosis of growth disorder, and estimation of height (11.1% ), and treatment using growth hormone (8.3%,).

Gilsanz and Ratib (2005) stated that the evaluation of skeletal age is important for the identification of growth disorders that could be categorized into two global groups based on distinct etiologies, prognoses or therapies. Initial growth disorder is caused by inherent defects in the skeletal growth process. For example, bone dysplasia could be due to an inherited defect or even prenatal problems that result in the reduction of diaphysis without essential delay of epiphyseal maturation. Therefore, during the period of growth, the potential normal skeletal growth is affected, although skeletal age is not postponed or is postponed much less than the height.

The second group of growth disorder concerns factors outside the skeletal growth process, which can adversely affect epiphyseal or even osseous maturation. These factors could be nutritional, or metabolic factors, or other unknown factors such as the idiopathic growth postponement syndrome. In this type of growth retardation, skeletal age, and height are often delayed to nearly similar degree. With medical treatment, however, it might be possible to achieve normal adult height.

It is difficult to differentiate between the two groups of growth deficiencies in those cases where bone age is postponed to a lower level when compared to the growth in height. Nevertheless, it is possible to differentiate primary and secondary growth failure by determining bone growth and bone age in the laboratory (Kaplan, 1990).

The height of children, who grow up under normal lifestyle conditions, is very much influenced by heredity. Hence, the final height of children could be postulated from the

heights of parents. Different techniques for height estimations, which consider parental height, have been proposed (Rosenfeld & Cohen, 2002).

Gilsanz and Ratib (2005) stated that a child’s height could also be estimated from the heights at an early age, with correlation in the order of 0.8. Although, young children are different mainly in the rate of development, some of them exhibit evident growth at quite on early age, whilst some have slower rate of growth, and finish skeletal growth quite late. Therefore, having skills in monitoring the rate of development will contribute to higher accuracy in estimation of height. A good way to acquire this skill is to make assessment of bone age, based on the hand-wrist image. The tables for estimation of final height based on height, bone age, age, sex and growth rate of bone have been published. Figure 4.1 shows the formula for the estimation of adult height proposed by Tanner et al. (1975):

For females, researchers have also used the time of menarche to enhance accuracy in their estimations of bone age. The tables of coefficients for estimation of adult height for boys and girls are presented in Appendix D.

Another issue regarding the status of bone age assessment in UMMC is time taken to evaluate each X-ray image. King (1994) estimated the time for conducting BAA using the Greulich and Pyle method is 1.4 minutes. However, the result from observational study

Predicted Final Height = Height Coefficient × Present Height (cm) + Age Coefficient × Chronological Age (years) + Bone Age Coefficient × Bone Age (years) +Constant

shows that the average time needed to assess the bone age, using a normal sample is 5 to 10 minutes. In the analysis of the data, 55.5% of respondents said they took from 5 to 10 minutes, 41.7% said that they spent from 10 to 15 minutes and 2.8% of respondents said they took from 15 to 20 minutes, to assess bone age using images of acceptable quality. Based on the result, it can be concluded that BAA is a time-consuming daily task in UMMC, especially, when a radiologist has to deal with many cases each day.

Number of Cases for BAA Frequency Percentage (%)

About 5 to 10 28 78.9

About 10 to 20 8 21.9

About 20 to 30 0 0

More than 30 0 0

Total 36 100

Main Reasons for BAA Ferequency Percentage (%)

Diagnosis of growth disorders 29 80.6

Estimation of height 4 11.1

Treatment of growth disorders

using hormones 3

8.3

The patients without any document to indicate the age

0 0

Others 0 0

Total 36 100

Table 4.6: Cases of BAA have to deal with in a week

Using the GP atlas for BAA has both advantages and disadvantages. The respondents replied to these questions differently. They were asked about the advantages and disadvantages of using the GP atlas as reported in the research by Garamendi et al., (2005). The respondents said that the GP method is easy to use, saves time, and is accurate. The disadvantages include it is time-consuming, has low accuracy, and the estimation is subjective.

From the feedback, 69.4% of the respondents said that it is easy to use the GP atlas and 22.2% said that produces accurate results, and only a few respondents (less than 10%) stated that it is time-consuming, or other reasons. The problems faced include: subjective estimation (52.8%), and time-consuming (36.1%). Furthermore, 8.3% of the respondents said that the GP method is not very accurate in estimation age for use in BAA.

The GP atlas has become the most popular standard for use in BAA. It contains two groups of normal radiographs of the hand-wrist of white girls and boys from upper middle-class families, who had participated in the Brush Foundation Growth Research from 1931 to 1942. When using the GP atlas, the image to be evaluated is compared to a large number of normal radiographs, and the age stated in the standard image that matches or most similar to images for evaluation, is the age of the children. Usually, it is quite easy to interpolate among the two standards to assign the correct age to the owner of an image. The obvious ease of use and also the speed, with which bone age could be determined, make the GP atlas the most popularly used standard of atlas for bone age assessment, in the world (Gilsanz & Ratib, 2005).

With regard to the normal error rate (estimation inaccuracy) of the current method, 36.1% of the respondents stated that the error rate is one to two years, 30.6% stated 6 to 12 months, 19.4% stated three to 6 months, 8.3% stated two to three years, and 5.6% stated two to three years (See Table 4.8). The difference in the error rates confirm that subjective estimation is the main problem in using the GP method. Thodberg et al. (2013) stated that human error resulting from low level of experience is the main reason of the low accuracy in manual method of bone age assessment.