A kezelés a röntgenfelvétel után kezdődik.

Both a words are the Hungarian definite article, meaning the.

• a kezelés = the treatment
• a röntgenfelvétel után = after the X-ray image / after the X-ray

Hungarian uses the definite article more regularly than English in some contexts, so seeing a twice in one sentence is completely normal.

után means after.

In this sentence:

• a röntgenfelvétel után = after the X-ray image / after the X-ray

Unlike English after, Hungarian után comes after the noun phrase it belongs to. So instead of saying after the X-ray, Hungarian literally says something like the X-ray after.

This is very common in Hungarian: many meanings that English expresses with prepositions are expressed with postpositions in Hungarian.

This is a very common learner question.

• kezd = starts something / begins something
• kezdődik = begins / starts (intransitive, something begins)

Here, the treatment is the thing that begins, so Hungarian uses kezdődik.

Compare:

• Az orvos kezdi a kezelést. = The doctor begins the treatment.
• A kezelés kezdődik. = The treatment begins.

So in your sentence, kezdődik is the natural choice because the subject is a kezelés.

The basic structure is:

• A kezelés = subject
• a röntgenfelvétel után = time expression
• kezdődik = verb

So literally:

• The treatment after the X-ray begins.

A natural English translation would be:

• The treatment begins after the X-ray.

Hungarian word order is more flexible than English, but this sentence is a very normal neutral way to say it.

Yes, absolutely.

Both are grammatical:

• A kezelés a röntgenfelvétel után kezdődik.
• A kezelés kezdődik a röntgenfelvétel után.

The first version often feels a bit more natural as a neutral statement, with the time phrase placed before the verb. The second is also fine and may sound slightly more like the speaker is first stating the treatment begins, then adding after the X-ray.

In Hungarian, word order often affects emphasis rather than basic grammatical correctness.

röntgenfelvétel is a compound noun:

• röntgen = X-ray
• felvétel = recording, image, shot, scan, taking

Together, röntgenfelvétel means X-ray image, X-ray film, or just X-ray, depending on context.

In medical translations, English often simply says X-ray, even if the Hungarian word is more literally X-ray image/recording.

Because után is a postposition, and many Hungarian postpositions take the noun phrase in its basic form.

So:

• a röntgenfelvétel után = after the X-ray

There is no extra case ending needed on röntgenfelvétel here.

This is different from some other Hungarian structures where the noun does take a case ending.

A rough pronunciation guide is:

• röntgenfelvétel ≈ RURNT-gen-fel-VAY-tel

A few helpful points:

• ö is somewhat like the vowel in German schön or French peu
• é is a long ay sound
• stress in Hungarian is always on the first syllable:
  RÖNT-gen-fel-vé-tel

You do not need to reduce unstressed vowels the way English often does; Hungarian vowels are usually pronounced clearly.

Because kezelés is a noun meaning treatment.

• kezelés = treatment
• kezelni = to treat

Your sentence is built around the noun the treatment:

• A kezelés ... kezdődik. = The treatment ... begins.

If you used kezelni, the structure of the sentence would need to be different, because kezelni is a verb, not a noun.

Usually not in this sentence if you want the natural meaning the treatment begins after the X-ray.

• A kezelés a röntgenfelvétel után kezdődik. = natural, definite
• Kezelés röntgenfelvétel után kezdődik. = sounds unnatural or telegraphic, like a note or headline

Hungarian normally uses the definite article when referring to specific, known things like the treatment and the X-ray in a medical context.

It can be used in more than one way.

1. Time

   • ebéd után = after lunch
   • a röntgenfelvétel után = after the X-ray

2. Order / sequence / following something

   • János után jön Péter. = Péter comes after János.

3. In some contexts, it can also suggest looking for or in pursuit of in fixed expressions, but that is a separate usage.

In your sentence, it is clearly the time meaning: the treatment starts later than the X-ray.

A very literal breakdown is:

• A = the
• kezelés = treatment
• a = the
• röntgenfelvétel = X-ray image / X-ray
• után = after
• kezdődik = begins

So, word-for-word:

• The treatment the X-ray after begins.

More natural English:

• The treatment begins after the X-ray.